Report of the RPII Visit to BNFL Sellafield

P.A. ColganD. PollardC. HoneC. McMahonA.T. McGarry

RPII 05/01

Report of the RPII Visit to BNFL Sellafield

Report of the RPII Visit to BNFL Sellafield

P.A. ColganD. PollardC. HoneC. McMahonA.T. McGarry

April 2005

Report of the RPII Visit to BNFL Sellafield

Contents

1. Introduction 1

2. Summary of Operations at BNFL Sellafield 2

2.1 Introduction 2

2.2 Reprocessing at BNFL Sellafield 2

2.3 The Magnox Operating Plan (MOP) 4

3. Site Visits 6

3.1 The Magnox Fuel Storage Pond and Decanning Facility 6

3.2 The Solid Active Waste Storage Facility 7

3.3 The Medium Active Concentrate (MAC) Storage Tanks 7

3.4 The Highly Active Liquor Evaporation and Storage (HALES) Plant 8

3.5 The Waste Vitrification Facility 9

3.6 The Thermal Oxide Reprocessing Plant (THORP) 10

4. Emergency Planning Arrangements at BNFL Sellafield 11

4.1 The BNFL Sellafield Reference Accident 11

4.2 Structure of Emergency Response 11

4.3 The Sellafield District Control Centre (DCC) 12

4.4 Security Issues post 9/11 12

5. Conclusions 13

5.1 Plant Operations 13

5.2 Radioactive Discharges 14

5.3 Emergency Preparedness 14

5.4 Terrorist Threats 15

6. References 16

ANNEX 1 17

ANNEX 2 21

ANNEX 3 28

Report of the RPII Visit to BNFL Sellafield 1

1. Introduction

In 2002 the Irish Government initiated international legal

proceedings against the United Kingdom (UK) under the United

Nations Convention on the Law of the Sea (UNCLOS) in relation to

the Sellafield MOX Plant. The Tribunal in the case issued an Order

on 24 June 2003 after hearing an application by Ireland for

Provisional Measures. The Provisional Measures Award

recommended inter alia that Ireland and the UK enter into

dialogue to improve cooperation and consultation between the

two Governments.

As part of this process the Irish Government expressed an

interest in further visits to BNFL Sellafield by officials of the

Radiological Protection Institute of Ireland (RPII). A previous fact-

finding visit had taken place in February 2000. Written proposals

for a visit were presented to the UK in January 2004. In their

response to the proposals, the UK invited the RPII, together with

relevant officials from the Department of the Environment,

Heritage and Local Government, to a background briefing at the

headquarters of the Health and Safety Executive in Bootle in

advance of a visit to BNFL Sellafield.

The background briefing, conducted over two-and-a-half days,

was comprehensive and contributed significantly to understanding

the regulatory approach by both the Health and Safety Executive’s

Nuclear Installations Inspectorate (NII) and the Environment

Agency (EA) and the regulatory regime currently in place at BNFL

Sellafield. The briefing also addressed the current principal

regulatory issues at BNFL Sellafield including details of a revised

Discharge Authorisation to be issued by the Environment Agency

to take effect in October 2004 and the considerations

underpinning the current regulatory obligations imposed by the

NII on the BNFL Sellafield site in relation to the reduction of the

Highly Active Liquor (HAL) stocks to buffer stock levels by 2015.

Five members of staff of the RPII visited BNFL Sellafield over the

period 23-24 September 2004. The purpose of the visit was to see at

first-hand a small number of on-site facilities of particular interest and

concern to Ireland and to explore the changing nature of operations

at the site. Issues of security were outside the scope of the visit.

The facilities included as part of the visit were:

• The redundant Magnox Fuel Storage Pond and Decanning

Facility;

• The Solid Active Waste Storage Facility;

• The Medium Active Concentrate (MAC) Storage Tanks;

• The Highly Active Liquor Evaporation and Storage (HALES)

Plant;

• The Waste Vitrification Facility (WVF); and

• The Thermal Oxide Reprocessing Plant (THORP).

Throughout the visit representatives of BNFL, the NII and the EA

accompanied the RPII delegation. The RPII met key BNFL

personnel in each of the areas visited as well as representatives of

the main worker unions.

On the second day of the visit the RPII discussed on-site and off-

site emergency arrangements with staff of BNFL Sellafield and the

emergency planning officer of Cumbria County Council

responsible for the BNFL Sellafield site.

A summary of the regulatory activities of the NII and of the EA can

be found in Annexes 1 and 2 respectively. General information on

emergency response planning and procedures in the UK can be

found in Annex 3.

Report of the RPII Visit to BNFL Sellafield2

2. Summary of Operations at BNFL Sellafield

2.1 IntroductionBNFL Sellafield is a 700-acre nuclear site in Cumbria in the North

West of England. The site is located close to the Irish Sea and at its

closest point (Clogher Head, Co. Louth) is approximately 112

miles from the Irish coastline.

In the late 1940s work commenced at the site on the construction

of two nuclear ‘piles’ for the production of plutonium for military

use. These are commonly referred to as the Windscale piles.

Electricity production commenced at the site in 1956 when the first

of four Calder Hall nuclear reactors came into operation. The last of

these closed down in March 2003. Sellafield was also the site of an

experimental reactor, the Windscale Advanced Gas-cooled Reactor

(WAGR), which is being decommissioned presently.

Today the main activities at BNFL Sellafield include the storage and

reprocessing of spent nuclear fuel1, the storage of plutonium and

uranium, the fabrication of mixed oxide (MOX) fuel and

decommissioning activities.

Previous non-commercial operations that have ceased have

resulted in large amounts of radioactive waste being stored in

various buildings around the BNFL Sellafield site. These are often

referred to as ‘legacy wastes’2. The clean-up3 of these facilities

represents a major challenge that has begun to be addressed and

will be the primary focus of future activities at BNFL Sellafield once

commercial reprocessing operations come to an end.

2.2 Reprocessing at BNFL SellafieldAfter being removed from a nuclear reactor, the spent nuclear fuel

still contains approximately 96% uranium. The remainder consists

of plutonium (1%) and a number of other highly radioactive

materials collectively called fission products. Spent fuel is highly

radioactive and generates a large amount of heat; it therefore

needs to be managed very carefully to protect both man and the

environment. One way of managing spent nuclear fuel is by

separating it into its constituent parts. This is called reprocessing.

Reprocessing was first developed to provide plutonium for military

purposes. Plutonium can also be used in a modern reactor design

called a fast breeder reactor but there is currently little interest in

developing this type of reactor. One further use for plutonium is in

the manufacture of mixed oxide (MOX) fuels for burning in some

commercial nuclear reactors. The majority of UK nuclear reactors

are not suited to the burning of MOX fuel. UK nuclear reactor sites

are shown in Figure 1.

There are two reprocessing plants on the BNFL Sellafield site. One

of these, the Magnox reprocessing plant, reprocesses spent fuel

from Magnox reactors. Magnox technology was developed in the

UK and is principally confined to the UK. The Thermal Oxide

Reprocessing Plant (THORP), which came into full operation in

1995, reprocesses uranium oxide fuel used in several different

types of nuclear reactors in the UK, Europe and Japan. Figure 2

shows the various steps in the reprocessing of spent nuclear fuel

through THORP.

Following delivery to the BNFL Sellafield site for reprocessing, the

spent fuel is stored in cooling ponds, often for several years, in

order to allow some of the heat to dissipate and the amount of

radioactivity present to reduce by natural decay. The spent fuel is

then chopped into small pieces and dissolved in hot nitric acid4.

The casing is segregated and stored as intermediate-level

radioactive waste. A solvent is then added that separates out the

uranium and plutonium for purification and storage. What remains

is high or medium-level radioactive waste in concentrated liquid

nitric acid.

1 Conventional nuclear fuel consists of a mixture of uranium-235 and uranium-238.This is used in a nuclear reactor to produce energy. ‘Spent nuclear fuel’ is nuclearfuel that has been removed from a nuclear reactor. Spent nuclear fuel containsuranium-235, uranium-238, plutonium and a number of highly radioactivematerials collectively referred to as ‘fission products’.

2 In the 2002 UK White Paper on managing the nuclear legacy (DTI, 2002), ‘legacywastes’ are defined in the following terms• those nuclear sites and facilities now operated by the United Kingdom Atomic

Energy Authority (UKAEA) and British Nuclear Fuels plc (BNFL), which weredeveloped in the 1940s, 50s and 60s to support the Government’s researchprogrammes, and the wastes, materials and spent fuel produced by thoseprogrammes; and

• the Magnox fleet of nuclear power stations designed and built in the 1960s and70s and now operated on the Government’s behalf by BNFL, plant and facilitiesat Sellafield used for the reprocessing of Magnox fuel and all associated wastesand materials.

3 ‘clean-up’ is defined as the decontamination and decommissioning of a nuclearlicensed site.

4 The casing of Magnox fuel is removed before the fuel is dissolved. In the case ofoxide fuels processed through THORP, the fuel and its casing are chopped intosmall pieces. The nitric acid dissolves the fuel but not the casing, which is thensegregated for storage as intermediate-level waste.

Report of the RPII Visit to BNFL Sellafield 3

Figure 1Location of BNFL Sellafield and UK Nuclear Reactor Sites

Torness

Hunterston A & B

Chapelcross

HartlepoolSellafield/2Calder Hall

Heysham I & II

Sizewell A & B

Bradwell

Dungeness A & BHinkley Point A & B

Oldbury

Berkeley

Trawsfynydd

Wylfa

Report of the RPII Visit to BNFL Sellafield4

Reprocessing generates large amounts of radioactivity for which

there is no end use. This waste material is classified according to its

radioactive content as high-, intermediate- or low-level waste. High-

level liquid radioactive wastes are stored in the Highly Active

Storage Tanks (HASTs) before being incorporated into glass blocks

(a process known as vitrification) for long-term storage.

Intermediate-level radioactive waste is stored on-site at BNFL

Sellafield while low-level radioactive waste produced at BNFL

Sellafield is disposed of at a nearby waste repository called Drigg.

Reprocessing also gives rise to liquid radioactive discharges into the

Irish Sea and gaseous radioactive discharges to the environment.

These discharges are classified as low-level radioactive wastes.

Reprocessing at BNFL Sellafield evolved into a commercial activity

in the 1980s, providing uranium and plutonium for reuse in the

manufacture of nuclear fuel. However, given the current low world

price for uranium it is cheaper to mine and mill fresh uranium than

to re-use uranium recovered during reprocessing. In the absence

of a fast breeder reactor programme the only alternative to long-

term storage or disposal of plutonium is the manufacture of MOX

fuel in the Sellafield MOX Plant. The plutonium is mixed with

uranium and the MOX fuel can be used in certain nuclear reactors

to generate electricity. There are currently no plans to produce

MOX fuel from the UK’s own plutonium stocks but some contracts

do exist with BNFL’s overseas customers for the conversion of

their plutonium into MOX fuel for burning in nuclear reactors in

their own countries.

On 1 April 2005 a new Nuclear Decommissioning Authority (NDA)

takes over responsibility for the management of all legacy wastes

at designated sites (NDA, 2004) as well as current and future

decommissioning programmes in the UK. The NDA also assumes

responsibility for the commercial activities on the BNFL Sellafield

site, namely the reprocessing operations at THORP and the

manufacture of MOX fuel.

2.3 The Magnox Operating Plan (MOP)The UK’s nuclear power programme, announced in 1955, called

for 5,000 megawatts of generating capacity through the

construction of a series of Magnox reactors across the country.

The fuel used in Magnox nuclear reactors consists of natural

uranium encased in magnesium alloy. When stored underwater,

Magnox spent fuel undergoes corrosion, initially of the

magnesium alloy cladding and subsequently of the uranium metal

within. Dry storage has also been considered but is not a proven

long-term management option, although interim storage of

Figure 2Reprocessing of Spent Nuclear Fuel through THORP

Fuel2Assemblies

Shipm

ent of Spent2

Reactor Fuel

Pluto

nium2

Oxide Liquid2

Discharges

Uranium2

Oxide

Liquid2Discharges

THORP2Storage Pond

Solid2Waste Store

Plutonium2Store

Uranium2Store

IRISH2SEA

Discharges to2Air & Sea

Discharges of2Gases to Air

High-Level2Waste Storage2

TanksReactor

Liquid2WasteTHORP EARPSpent2

Reactor Fuel

Report of the RPII Visit to BNFL Sellafield 5

Magnox spent fuel does take place at the Wylfa nuclear power

plant. According to the UK Radioactive Waste Management

Advisory Committee “even if dry stored…[Magnox spent

fuel]…would need to be in a carefully controlled environment and

would not be in line with the concept of passivity. If a policy of

deep disposal were ultimately pursued, the fuel would also then

subsequently have to be suitably conditioned, given that it would

still be reactive in a geological environment. Currently, no

industrial-scale process exists to do this, other than reprocessing

itself. It is therefore rational to continue to reprocess the [Magnox]

spent fuel” (RWMAC, 2000). Thus the UK’s policy for managing

Magnox spent fuel is based primarily on the reactivity of the fuel

and the fuel cladding, which in turn makes it unsuitable for

ultimate disposal unless it is reprocessed.

The only Magnox stations still operating are in the UK, where they

produce approximately 8% of the UK’s electricity. Previously, Magnox

power stations operated at Latina in Italy and Tokai Mura in Japan.

In May 2000 BNFL announced the planned closure dates for its

remaining Magnox reactors. Following a number of safety-related

incidents at both Calder Hall and Chapelcross, the closure dates

for these reactors were brought forward as their continued

operation could not be justified economically. The UK Strategy for

Radioactive Discharges 2010-2020 (DEFRA, 2002) also brought

forward the closure dates for Oldbury and Wylfa (previously 2013

and 2016/2021 respectively).

The most up-to-date timetable for closure, defuelling and

decommissioning of the Magnox stations is given in Table 1.

The Magnox Operating Plan (MOP) places priority on the

reprocessing of Magnox spent nuclear fuel. OSPAR Contracting

Parties, including the UK, undertook in 1998 to reduce radioactive

discharges so that, by 2020, the additional concentrations in the

marine environment above historic levels, arising from such

discharges, are close to zero (OSPAR, 1998). This goal is to be

achieved through progressive and substantial reductions in

radioactive discharges.

The Magnox reprocessing plant is due to cease operation by the

end of 2012. This date is consistent with the closure date for the

final Magnox station (Wylfa) in 2010 and the NII specification to

reduce HAL volumes in the HASTs by 2015 (HSE, 2000a). To

achieve the 2012 operational deadline requires approximately

eight years of good operation of all plants – including the liquid

effluent treatment plants - linked to the Waste Vitrification Facility.

Procedures are in place to monitor the implementation of the MOP

so that steps can be taken if problems arise. If the HAST

specification is not complied with, then the NII has the authority to

close the Magnox stations at an earlier date or to constrain the

operation of THORP so as to give priority to Magnox reprocessing.

Restricting the operation of THORP would still allow the 2015

specification to be met but would extend the time period over

which THORP reprocessing would take place.

Table 1Current Status of UK Magnox Reactors

Station Commissioned Current Status

Berkeley 1962 closed 1989 – being decommissioned

Hunterston A 1964 closed 1989 – being decommissioned

Trawsfynydd 1965 closed 1991 – being decommissioned

Hinkley Point A 1965 closed 2000 – being defuelled

Bradwell 1962 closed 2002 – being defuelled

Calder Hall 1956 closed 2003 – awaiting defuelling (2005)

Chapelcross 1958 closed 2004 – awaiting defuelling (2005)

Dungeness A 1965 to close 2006

Sizewell A 1966 to close 2006

Oldbury 1967 to close 2008

Wylfa 1971 to close 2010

Report of the RPII Visit to BNFL Sellafield6

3. Site Visits

3.1 The Magnox Fuel Storage Pond and Decanning FacilityThe Magnox Fuel Storage Pond and Decanning Facility came into

operation in 1959. Its principal role was to receive and store

irradiated spent fuel from Magnox reactors and to remove the fuel

cladding (a process called ‘decanning’) prior to the fuel being

reprocessed. Initially a wet decanning process was used but later a

dry decanning facility was added. A new Magnox Fuel Handling

Plant was commissioned in 1986 and a phased handover to the

new plant took place in the early 1990s.

The Magnox spent fuel is stored underwater in a pond that is

exposed to the open air. The pond is approximately 60 m in length

and 12 m in width. The casing of Magnox fuel is subject to corrosion

and this limits the amount of time for which it can be stored

underwater to approximately one year. Around 1974 a reprocessing

shutdown led to the accumulation of spent Magnox fuel in the

storage ponds; this started to corrode and leak, making it almost

impossible, with the technology available at the time, to recover and

reprocess the contents. Over the years this has resulted in the

accumulation of highly radioactive spent fuel in the form of sludge

on the bottom of the storage ponds, which by the mid 1980s meant

that it was no longer feasible to operate the plant reliably. This

sludge contains uranium, plutonium and a range of fission products.

Around this time the ponds were also used to store other

radioactively contaminated material generated in the plant. This

includes material such as iron bars, pumps, solid material

contaminated as a result of routine operations, etc. The total

inventory of contaminated material and its radioactive content is

not accurately known and this adds to the complexity of the

clean-up operations.

The NII regards the clean-up of this facility as one of the major on-

site priorities and it has specified a date of August 2010 by which

90% of the sludge in the tanks must be removed. A further

specification requires that at least 80% of the total volume of all

sludges originating from operations prior to 1 August 2000 and

which have been accumulated as radioactive waste shall be stored

in a passive form by 2020. Material retrieved from the ponds will

be classified as intermediate-level waste i.e. it will be encased in

concrete, placed in metal drums and stored on the BNFL Sellafield

site. BNFL has put in place a project team with an annual budget

of £150 million to decommission the facility. While considerable

advances have been made in improving the building condition,

developing contingency plans and retrieving some of the wastes,

there are many unknowns and unforeseen problems arise on a

regular basis (Travis, 2003).

The dose rates inside the plant present a major constraint on

working times and mean that much of the work has to be done

remotely. Dose rates along the south wall of the pond, for example,

are as high as 1 Sievert per hour in places. This compares with the

annual dose limit for a radiation worker of 0.02 Sievert. On-going

work is necessary to upgrade basic safety facilities and to stabilise

and make safe the structures in order that the decommissioning

work can continue. These factors greatly increase the technical

complexity of the decommissioning operations.

After the NDA takes over responsibility for clean-up operations at

several UK sites, including BNFL Sellafield, in April 2005, it will

have available to it an annual budget of £1.2 billion for each of the

first three years of its operation. While the NDA is free to set its

own priorities for the clean-up of the UK’s nuclear sites, there is

confidence that the current clean-up and decommissioning

programme for this plant will continue.

The water in the pond serves the dual purpose of cooling the

pond contents while also acting as a shield to reduce radiation

doses to workers. These waters are routinely transferred to the

Site Ion Exchange Effluent Plant (SIXEP), where they are treated to

remove radionuclides prior to discharge, and replaced by fresh

uncontaminated water. As part of the new EA Discharge

Authorisation for BNFL Sellafield, which came into force on 1

October 2004, BNFL is required to estimate the actual discharges

from all of its major operations. The clean-up and

decommissioning of the Magnox Fuel Storage Pond and

Decanning Facility is regarded as one such major operation.

Estimated discharges for current operations must be submitted to

the EA on an annual basis with the first such submission required

at the end of June 2006.

Report of the RPII Visit to BNFL Sellafield 7

3.2 The Solid Active Waste Storage FacilityThe Solid Active Waste Storage Facility was commissioned in 1952

for the dry storage of intermediate-level waste, principally the casings

that had been removed from spent fuel. The facility is a reinforced

concrete structure sub-divided into a number of compartments,

normally referred to as ‘silos’. Routine tipping of waste into these

silos ceased in 1966. However small quantities of miscellaneous

beta/gamma wastes were placed in the silos up to 1969.

In addressing the on-going maintenance and eventual

decommissioning of the facility there are two principal issues. The

first is the potential for a fire and/or explosion from Magnox

casings stored in a dry environment. This risk was previously

evaluated by BNFL and considered unacceptable with the result

that the building is now maintained in an argon-rich environment.

Argon is an inert gas that significantly reduces the risks of fire from

dry storage of fuel cladding. To ensure an uninterruptible argon

supply, back-up safety systems have been installed and are

regularly tested. The second issue is the very high radiation levels

present. These are due to a combination of, the small amounts of

spent fuel that remained attached to the casing at the time of

mechanical separation, irradiation products and the miscellaneous

beta/gamma emitters referred to above.

Waste material from the facility is classified as intermediate-level

waste. As with the sludges and other waste materials arising from

the clean-up operations at the Magnox Fuel Storage Pond and

Decanning Facility, this waste will be retrieved, packaged and

stored on-site in metal drums. However the timescale for these

activities has yet to be established.

3.3 The Medium Active Concentrate (MAC) Storage Tanks The MAC storage tanks were built in the late 1940s and are used

to store liquid wastes generated by Magnox reprocessing before

being sent to the Enhanced Actinide Removal Plant (EARP). In

EARP, chemical treatment of the wastes removes much of the

strontium-90, caesium-137, americium-241 and plutonium prior to

discharge to the Irish Sea. Since March 2004, the chemical

tetraphenylphosphonium bromide (TPP) has been added to MAC

as it passes through EARP and this removes the bulk of the

technetium-99 present in this waste stream, resulting in a

significant reduction in discharges of technetium-99 into the Irish

Sea. Current and future arisings of MAC are diverted directly to

the HALES building where they are added to high-level

radioactive wastes prior to vitrification.

The NII has expressed its “…concern about the prolonged use of

..[the tanks].. to store MAC because of the age of the tanks (built

in the late 1940s) and the deteriorating condition of the building

structure”5. Specifically the NII cited that the roof of the building

could collapse, damaging the tanks and leading to a release of

radioactivity to the environment. The NII is satisfied that the tanks

are structurally sound up to 2006. The current discharge strategy

will see the tanks emptied by this date and this will further reduce

the overall hazard on the site. Over the past year approximately

65% of the stored MAC has been removed from the tanks.

The BNFL Sellafield discharge authorisation issued by the EA will

allow the contents of the MAC storage tanks to be emptied within

the timescale acceptable to the NII. At present the EA is

considering a request from BNFL to accelerate the treatment and

discharge of MAC. If this proceeds, the on-site hazard will be

reduced more quickly than is presently foreseen. MAC is normally

stored for a period of three years in order to allow the ruthenium-

106 content to reduce by radioactive decay. A change to the

present timetable will reduce the storage time to less than three

years and this will result in a small increase in the quantity of this

radionuclide discharged to the Irish Sea6.

Ruthenium-106 is not presently detected in the Irish marine

environment and it is unlikely that the small increased discharges

resulting from the earlier emptying of the MAC storage tanks will

change that. However, in future years BNFL Sellafield is likely to

handle spent fuels which have spent longer times in the reactor and

which are stored for shorter periods prior to reprocessing. These two

factors could potentially further increase the discharges of ruthenium-

106 to the Irish marine environment if no abatement is applied.

5 Letter to Rt. Hon. Margaret Beckett, M.P. from Laurence Williams, NII ChiefInspector dated 13th January 2003.

6 Ruthenium-106 has a half-life of approximately one year and therefore prolongedstorage can significantly reduce the amount present. EARP does not removeruthenium-106 from MAC prior to discharge.

Report of the RPII Visit to BNFL Sellafield8

3.4 The Highly Active Liquor Evaporationand Storage (HALES) Plant The HALES Plant contains over 90% of the on-site radioactivity in

the form of waste and is where the Highly Active Storage Tanks

(HASTs) are located. The HASTs contain high-level liquid

radioactive wastes, commonly referred to as Highly Active Liquors

(HAL), awaiting vitrification.

On arrival, waste streams sent to the HALES plant are evaporated

to reduce the volume of material that has to be managed. There

are two evaporation plants – one for Magnox wastes and one for

THORP wastes – and a third (back-up) evaporator has recently

been recomissioned. The volume reduction achieved by

evaporation is typically a factor of 125. The waste is then

transferred to one of the HASTs and different tanks are used for

Magnox and THORP wastes.

There are 21 HASTs, all of which are located in the HALES

building. The first eight HASTs were commissioned in 1955 and

brought into active use between 1955 and 1970 as the volume of

waste produced increased. Each of these has a working volume of

70 cubic metres. The remaining 13 HASTs were built during the

1970s and 1980s and each has a working volume of 145 cubic

metres. For safety reasons, a policy of keeping one tank empty for

every three in use has always been maintained in the event that

one of the other HASTs needs to be emptied at short notice.

The HASTs are housed in thick reinforced concrete cells. Because

of the very significant heat generating capacity of the waste (up to

several kilowatts per cubic metre) the tanks require continuous

cooling to prevent evaporation and, ultimately in the case of those

tanks with the larger radioactive inventories, boiling and release to

atmosphere of their contents.

For safety reasons the HASTs are also segregated into ‘cells’ to

provide isolation from the other tanks. The first eight tanks were

installed two per cell while the remaining 13 tanks were installed

one per cell.

Most of the waste stored in the HASTs consists of long-lived

radioactive materials. The most important of these is caesium-137,

which accounts for about 10% of the total inventory. The next

most important radionuclides (in terms of quantity stored) are

strontium-90, caesium-134 and ruthenium-106. Because the

stored wastes are derived from reprocessing, much of the

plutonium has already been removed and only trace amounts are

present in the HASTs.

RPII staff previously examined safety documentation relating to

the HASTs, the Continued Operation Safety Report (COSR) over a

two-week period in February 2000 (Turvey and Hone, 2000). The

main conclusions of that examination were that the risk of damage

from a severe earthquake had not been fully analysed and that,

while the probability of an accident leading to a significant release

of radioactivity was low it could be reduced further through the

implementation of certain measures including, in particular,

increasing the level of independence of the cooling water

supplies. These issues were discussed with appropriate personnel

during the course of the site visit.

The RPII team was advised that the safety case relating to severe

earthquake damage, much of which would also apply to a terrorist

attack involving the intentional crashing of a heavy aircraft into the

building, has been completed and that the NII accepts that no

further structural modifications are required. The team were also

advised that the level of independence of the different cooling

water supplies has been increased since the February 2000 visit.

The issue of the detection of ‘spikes’ or ‘hot-spots’ of activity in the

cooling jacket in HAST 13 as referred to in the RPII Annual Report

and Accounts 2003 was discussed in detail. At the time of our visit

we were advised that, while the source of the contamination had not

been fully identified, it was believed to have originated from cross

contamination from cooling water in an internal cooling coil. (The

cooling coils and cooling jackets share a common water supply).

Minor cracks in internal cooling coils do occur from time to time and

while the pressure in the cooling coils is kept higher than the

pressure of the HAL to prevent HAL entering a damaged cooling

coil, some transfer of radioactivity through mixing is a possibility.

Report of the RPII Visit to BNFL Sellafield 9

The Institute was subsequently advised by the NII that the spike in

activity in the cooling jacket in HAST 13 is now believed to be due to

a microscopic fissure in the tank wall, as a result of stress corrosion of

the steel, which has allowed nanolitre quantities of HAL to leak out.

While there are no immediate safety concerns, further studies are

being conducted by BNFL and the NII is monitoring this work and

considering the implications for storage of HAL. This incident is

clearly of greater significance than if the activity in the spike was due

to cross contamination resulting from a leaking internal cooling coil

and provides further evidence that the long-term storage of high-

level radioactive waste in liquid form is not sustainable.

The NII recently advised the Institute that a small activity spike, at

too low a level to characterise, has been detected in HAST 12. An

enhanced surveillance programme has been put in place to

monitor this HAST. The activity spikes in both HASTs are under

active investigation by both BNFL and the NII. The NII has

acknowledged that these events are “a safety concern, as well as

potentially an additional constraint on the efficiency of operations”

(HSE, 2005).

The NII has specified that BNFL must reduce the volume of HAL

stored in the HASTs to a ‘buffer’ volume of 200 m3 by 2015. The

NII believes that this requirement is necessary to reduce overall

hazard at the BNFL Sellafield site (HSE, 2001). In specifying this

requirement, the NII has taken into account the need to reduce

the volume of stored HAL as quickly as possible while still

ensuring that the stocks of spent fuel currently in storage on site

and awaiting reprocessing are dealt with in a timely manner. The

NII believes that the current arrangements are the best solution for

dealing with the many hazards that are present on the site.

The current volume of HAL in the HASTs is approximately 1400 m3.

To meet the NII requirements, this volume must be reduced by 35 m3

per year for the next number of years and this is currently being

achieved. Once THORP and Magnox reprocessing end in 2010

and 2012 respectively there will be a significant reduction in the

volume of HAL generated and this will allow the rate of volume

reduction in the HASTs to be increased.

The NII is on record as saying that, if there are indications that

these deadlines will not be met, it will use its regulatory powers to

instruct BNFL to cease temporarily the reprocessing of oxide spent

nuclear fuel through THORP. This is consistent with the Magnox

Operating Plan (MOP), which places priority on the reprocessing

of Magnox spent nuclear fuel. This is discussed in greater detail in

Section 2.3.

3.5 The Waste Vitrification Facility In the early years of Magnox reprocessing research was carried

out into the treatment and long-term management of the HAL

stored in the HASTs. However, it was subsequently decided to

invest in a vitrification process developed in France and in 1990 a

Waste Vitrification Facility (WVF) came into operation. This facility

encapsulates the HAL in glass blocks for long-term storage. The

WVF had two vitrification lines but these failed to operate at full

capacity due to operational difficulties associated in part with the

very high temperatures of the materials passing through the plant.

In January 2002 the commissioning of a third vitrification line

commenced and this came into full operation in July 2004.

There are many factors to consider when dealing with the

vitrification and storage of HAL: it is highly radioactive; it contains

acids that are corrosive in nature; it generates considerable

amounts of heat and it contains different mixes of radionuclides

depending on whether it originated from Magnox or THORP

reprocessing. The process of vitrification involves the blending of

wastes from the different HASTs in order to minimise the number

of glass blocks that have to be produced and maximising the

amount of radioactivity in each, while at the same time taking

account of the chemical nature of the different liquors. Following

blending, the waste is sent by pipe to the WVF.

On arrival at the WVF, the HAL is passed through a calciner to

transform it into powder form. Glass-making substances are added

and the material is heated and melted to form a viscous liquid that

is then poured into stainless steel containers. The glass cools and

solidifies, thereby binding the radioactivity into a structure that is

chemically inert and shows long-term resistance to leakage.

The stainless steel containers are transferred to a shielded storage

area that has the capacity for 8,000 containers. Presently the store

is less than half full. BNFL’s current overseas contracts will

generate approximately 3,000 containers and from 2007 onwards

these will be returned to the customer by ship. BNFL’s

reprocessing contracts with its UK customers are expected to

generate considerably less than 8,000 containers.

Report of the RPII Visit to BNFL Sellafield10

No decision has been made on the long-term storage or disposal

of high-level radioactive waste in the UK. However, the UK

recently established an independent body, the Committee on

Radioactive Waste Management (CoRWM) to review the available

options and to provide its recommendations to Ministers by July

2006. The current inventory of radioactive waste at BNFL Sellafield

is given in Table 2.

Table 2Current Inventory of Radioactive Waste

at BNFL Sellafield1

Radioactive Waste Form Volume (m3)

High Level Waste

HASTs (liquid)2 1400

Vitrified Waste (solid)3 745

Intermediate Level Waste4 75,400

Low Level Waste5 1 x 106

1 based on April 2001 values given in DEFRA (2001).

2 value as of end December 2004.

3 it is estimated that the total volume of vitrified waste generated from current

reprocessing contracts will be 1510 m3, of which approximately 400 m3 belongs to

BNFL’s overseas customers (CoRWM, 2004).

4 the majority, but not all, of this waste originates at BNFL Sellafield.

5 low-level radioactive waste produced at BNFL Sellafield is disposed of at Drigg,

approximately 6 km south of the BNFL Sellafield site. This disposal is controlled

through authorisations issued by both the NII and the EA.

Efficient operation of the WVF is the key to volume reduction of

HAL in the HASTs. If the vitrification throughput is reduced, this in

turn limits the allowable production of HAL (as the volume in the

HASTs must decrease rather than increase) and could impact

significantly on THORP reprocessing. This is also discussed in

some detail in Section 2.3. For this reason considerable effort is

being put into upgrading the first two vitrification lines in an effort

to process the volume of HAL in storage in the HASTs at a faster

rate than that specified by the NII.

Neither the operations in the Waste Vitrification Facility or HALES

give rise to liquid discharges to the environment. All such waste

streams are recycled to the evaporators in the HALES building.

3.6 The Thermal Oxide Reprocessing Plant(THORP)In March 1977 BNFL applied to Cumbria County Council for

approval to construct THORP. Following a public inquiry, THORP

was approved in 1978 and subsequently built at a total cost of

£2.8 billion. Commissioning of THORP commenced in 1994 and

the plant came into full operation in early 1995.

The reasons for Magnox and THORP reprocessing are

fundamentally different. Originally Magnox reprocessing was

undertaken to produce plutonium for the UK’s nuclear weapons

programme. At present, the reprocessing of Magnox spent fuel is

seen as the best management option for a material that is reactive

and unstable when stored under water or in open air for prolonged

periods. Conversely, THORP reprocessing was set up as a

commercial venture to provide operators in the UK and abroad

with a spent fuel management route and/or to extract reusable

uranium and plutonium from their spent uranium oxide fuel.

THORP reprocesses spent fuel used in several different types of

nuclear reactor including advanced gas cooled reactors and light

water reactors. In terms of tonnage, THORP’s main customer is

Japan, followed by British Energy. Its principal European customer

is Germany but contracts also exist with utilities in Switzerland,

Italy, Spain, Sweden and the Netherlands.

THORP is in stark contrast to the older plants visited. It is clearly

more modern and has a greater degree of automation. The

aerial and liquid discharges from THORP are also less than those

from Magnox reprocessing for the same throughput of spent

fuel. The mix of radionuclides discharged and their relative

percentages are also different from those discharged as a result

of Magnox reprocessing.

The future planned throughput of spent fuel through THORP

would result in all existing reprocessing contracts being completed

by 2010. However, additional reprocessing contracts may be

entered into, but only with the consent of the UK Government.

Presently, any requests for approval of such contracts are made by

BNFL to the UK Government, its sole shareholder. As of 1 April

2005 these submissions, should any arise in respect of new

contracts, will be made by the NDA.

Report of the RPII Visit to BNFL Sellafield 11

4. Emergency Planning Arrangements at BNFL Sellafield4.1 The BNFL Sellafield Reference AccidentAll nuclear sites in the UK are required by law to define a

bounding reference accident scenario for the purposes of off-site

emergency planning. The reference accident must be based on

the concept of the worst credible accident, which is reasonably

foreseeable at the site, taking into account all of the facilities on

the site (see Annex 3). The NII must approve the reference

accident for each nuclear site and this is then used as the basis for

deciding the size of the Detailed Emergency Planning Zone

(DEPZ). Within the DEPZ detailed plans must be prepared for the

implementation of applicable off-site countermeasures.

Formerly the reference accident for the BNFL Sellafield site was

based on the Calder Hall reactors. Since the closure of these

reactors in 2003, the reference accident has been based on a leak

into the coolant circuit in one of the Highly Active Storage Tanks

(HASTs) leading to an environmental release via one of the HAST

cooling towers. While precise information on the reference

accident source term or amount of radioactivity likely to be

released is not made publicly available by the UK authorities for

security reasons, it is possible, on the basis of the size of the DEPZ

to make a crude estimate of the size of the source term. This was

found to be equivalent to a small percentage of the inventory for

one of the older HASTs or less that 1% for one of the newer

HASTs, based on the HAST inventories previously reported by the

RPII (Turvey and Hone, 2000).

While the hypothetical release is somewhat smaller for the HASTs

than was the case for the reference accident based on the Calder

Hall reactors, the difference is small and the NII decided to leave the

size of the DEPZ unchanged at 2 km. However, since the current

reference accident does not involve any release of iodine-131 and

since there is no longer a source of iodine-131 at BNFL Sellafield,

the distribution of stable iodine tablets as a countermeasure for the

site is no longer warranted and has been discontinued.

The decision to implement a particular countermeasure (such as

sheltering or the administration of stable iodine) in a given set of

circumstances is generally based on consideration of the benefits

(in terms of reduction in radiation exposure) and the risks

(disruption to normal living) associated with the countermeasure.

In order to assist decision makers radiation doses known as an

Emergency Reference Level (ERL) have been defined in advance,

at which the benefits are likely to outweigh the detriment

associated with implementing the countermeasure.

4.2 Structure of Emergency ResponseThe emergency planning infrastructure in place on the BNFL

Sellafield site includes a site emergency response centre equipped

with the necessary communications infrastructure and access to

site monitoring systems and other response resources. This centre

is at all times manned by the BNFL Sellafield duty site supervisor.

The key facilities of the emergency response centre are duplicated

at a second facility on the site remote from the first. The site

emergency response centre manages all communications between

the site and outside agencies such as the NII, DTI and the local

authority. In addition to the site emergency response centre there

is a network of 12 local response centres located around the BNFL

Sellafield site for the management of emergencies at facility level.

All of the local response centres are identically equipped and are

used regularly for drills and response training.

There are three classifications of emergency for the BNFL

Sellafield site, namely a facility emergency, a site emergency and a

nuclear emergency.

• A facility emergency is defined as an emergency confined to a

single facility and which does not have implications for the

wider site. The response to a facility emergency is managed by

the facility management from a local response coordination

centre;

• A site emergency is defined as an emergency, which affects

more than a single facility but does not have any off-site

implications. The site management manages the response to a

site emergency. Coordination of the initial response is the

responsibility of the duty site supervisor. The site response is

managed from the site emergency control centre, where a site

response coordination team is assembled. Management of the

response at a facility level, however, continues to be the

responsibility of the management for the affected facilities;

and

• A nuclear emergency is defined as an emergency with off-site

consequences. The on-site response is coordinated from the

site emergency control centre while the off-site response is

coordinated from the off-site facility (OSF), which in the BNFL

Sellafield emergency plan is referred to as the District Control

Centre (DCC).

Report of the RPII Visit to BNFL Sellafield12

The site emergency planning officer has responsibility for on-site

planning and coordination with the local authority, Cumbria

County Council. A detailed programme of exercises and

emergency response training is in place for coordination teams,

fire fighters, monitoring teams, etc.

4.3 The Sellafield District Control Centre (DCC)The Sellafield DCC is a purpose-built facility located

approximately 10 km from the BNFL Sellafield site. This facility is

managed by Cumbria County Council but is resourced by BNFL.

The BNFL Sellafield emergency plan envisages that in the event

of an emergency each of the agencies with responsibility for off-

site measures would send a representative to the DCC for the

purpose of coordinating the interagency response. Each agency is

allocated a room with basic IT and communications facilities and a

central area is designated for coordination group meetings. An IT

based information management system is used so that all groups

are kept up to date with developments. A media briefing centre

has been established at a Whitehaven school located

approximately 4 miles from the DCC. The key DCC facilities are

duplicated at a second site.

4.4 Security Issues post 9/11As indicated in the Introduction, discussion of security measures

was not included in this visit. However, since the RPII last visited

the BNFL Sellafield site in 2000, it was evident that a number of

security enhancements have been introduced. Some of the more

obvious manifestations of this enhanced security include:

• The upgrade of fire fighting facilities to deal with the impact of

a major air crash on the site. This has included the

procurement of two airport foam fire tenders and associated

equipment and training;

• The introduction of enhanced perimeter security including

anti-ramming barriers at gates and the use of an increased

number of armed guards;

• The introduction of physical barriers and access restrictions

around individual facilities;

• The construction of heavy barriers around more vulnerable

facilities; and

• The introduction of increased security for visitors to the site.

Report of the RPII Visit to BNFL Sellafield 13

5. Conclusions

5.1 Plant OperationsBNFL Sellafield is an extensive and complex site and there are

several significant hazards present on it. These include, but are not

limited to, the liquid radioactive wastes stored in the Highly Active

Storage Tanks (HASTs), the spent nuclear fuel in storage awaiting

reprocessing and the legacy wastes present in a number of

facilities across the site. The approach being adopted by the

nuclear regulator, the Health and Safety Executive’s Nuclear

Installations Inspectorate (NII), to reduce overall hazard at the site

is to address hazards in parallel. Thus reprocessing and the

management of legacy wastes are continuing while at the same

time the volume of liquid radioactive waste in storage in the

HASTs is being progressively reduced.

The NII requires BNFL to prioritise the reprocessing of Magnox

fuels over oxide fuels. This is because of the instability of Magnox

fuel, particularly under wet storage conditions. If the timetable set

by the NII for completing Magnox reprocessing is interrupted, the

reprocessing of oxide fuels through THORP will be delayed,

thereby extending the lifetime of that plant. The option of further

reprocessing contracts for THORP has not been ruled out but such

a decision is no longer in the hands of BNFL and can only be taken

by the UK Government.

The schedule for the completion of the current reprocessing

contracts is 2010 for oxide fuels and 2012 for Magnox fuels. These

dates are linked to the planned closure programme for Magnox

reactors and the existing reprocessing contracts that BNFL has

entered into with both its UK and overseas customers.

Compliance with these deadlines will require ongoing reliable

throughput of both fuel types at the rates that are only now being

achieved. On the basis of information supplied to the Institute, it is

difficult to see how this can be achieved without also increasing

some radioactive discharges to the environment.

While reprocessing continues, the NII has also stipulated that the

volume of liquid waste stored in the HASTs is to be progressively

reduced at an annual rate of 35 m3 up to 2010 and at a faster rate

thereafter. By July 2015 the volume stored must be reduced to 200 m3

or less. The content of the HASTs currently represents over 90% of

the inventory of radioactivity in the form of waste on the BNFL

Sellafield site.

The recent identification of ‘spikes’ or ‘hot-spots’ of activity in

HASTs 12 and 13 is a matter of concern. While the leaks involve

minute volumes of liquid and have not resulted in a release of

radioactivity to the environment, they do call into question the

long-term integrity of the tanks and underline that the storage of

high-level radioactive waste in liquid form is not sustainable.

The vitrification plant plays a key role in the ability of BNFL Sellafield

to meet its targets over the next few years. If this plant fails to meet

programme requirements, the volume of radioactive waste in

storage in the HASTs can only be controlled by reducing

reprocessing, which in turn means that the 2010 and 2012 deadlines

will be at risk. A possible option would be to close down the

remaining Magnox stations prematurely but as time passes this

would have a progressively smaller impact on the volume of fuel to

be reprocessed. This is because the amount of Magnox fuel already

in reactors or in storage awaiting reprocessing greatly exceeds the

amount of new fuel that will be placed in reactors between now and

the end of the Magnox generating programme in 2010.

At present the major challenge at the BNFL Sellafield site is the

management of legacy wastes. Already the clean-up and

decommissioning of the Magnox Fuel Storage Pond and

Decanning Facility is a significant technical and engineering

challenge with anticipated expenditure up to 2020 of the order of

£150 million per year. The extent to which these operations will

give rise to radioactive discharges has not yet been quantified and

it is too early to say whether future discharges will be greater or

less than those attributable to reprocessing. The UK has indicated

that it will be reviewing its Discharge Strategy (DEFRA, 2002) to

take account of the management of legacy wastes.

Once reprocessing comes to an end and the legacy wastes have

been treated, decommissioning of the BNFL Sellafield site will be

the main on-site activity. The extent of the challenges facing BNFL

and its UK regulators should not be underestimated.

Decommissioning, by its nature, is a slow process that extends

over several decades and current estimates are that

decommissioning and final site remediation of BNFL Sellafield will

not be completed until about 2150 (i.e. 150 years from now).

Ensuring that the resources necessary to support this work are

maintained over this timescale will clearly be a significant

challenge. Decommissioning will also give rise to as yet

unspecified radioactive discharges.

Report of the RPII Visit to BNFL Sellafield14

Responsibility for the management of legacy wastes passes to the

Nuclear Decommissioning Authority (NDA) on 1 April 2005. The

NDA will also assume responsibility for the commercial operations

at BNFL Sellafield and the income generated will be used to fund

clean-up operations. In the Institute’s opinion, this dual

responsibility is not ideal and could result in a situation where

additional reprocessing contracts with overseas customers are

entered into to generate income that would otherwise need to be

provided by central Government. The detail of the way in which

the NDA will operate, and the nature of its working relationship

with the NII and the EA, is still evolving. Both regulatory agencies

have confirmed that the protection of workers, the public and the

environment will continue to be their priorities.

5.2 Radioactive DischargesThe new Discharge Authorisation issued by the Environment

Agency (EA) and which came into effect in October 2004 adopts

an integrated approach to the control of discharges and emissions

from BNFL Sellafield as well as requiring more comprehensive

reporting by BNFL. While the new Discharge Authorisation

reduces the discharge limits for a number of radionuclides, there is

still considerable headroom available to BNFL i.e. the authorised

discharge is still considerably greater than the current rate of

discharge. The new Discharge Authorisation therefore does not

guarantee a reduction in discharges and can be used by BNFL

Sellafield to accommodate any increase in discharges arising from

the increased reprocessing of spent fuel previously mentioned.

The introduction of a new abatement technique involving the

addition of the chemical tetraphenylphosphonium bromide (TPP)

prior to the discharge of Medium Active Concentrate (MAC) has

been highly successful in removing technetium-99 from liquid

discharges, thereby allowing technetium-99 to be stored in solid

form. The technetium-99 site discharge limit has been decreased

from 90 terabecquerels (TBq) to 20 TBq per year. It is anticipated

that all MAC currently in storage will be processed before the end

of 2006 and indications are that this deadline will be met. As all

new significant arisings of technetium-99 generated by Magnox

reprocessing are now being diverted directly to vitrification, it is

expected that a further reduction in the technetium-99 discharge

authorisation (to 10 TBq per year) will come into operation in early

2007, at the latest. The TPP procedure has already significantly

reduced discharges of technetium-99 from the BNFL Sellafield site

into the Irish Sea. This initiative will assist the UK in meeting its

OSPAR obligations.

5.3 Emergency PreparednessEmergency preparedness arrangements are in place to deal with

incidents and accidents affecting the Sellafield site and the

surrounding area. These are regularly tested and comply with the

Radiation (Emergency Preparedness and Public Information)

Regulations, 2001 (REPPIR).

A reference accident, defined as the worst credible accident that is

reasonably foreseeable at the site, has been detailed and

approved by the NII. The exact details of the reference accident

were not made available to the Institute for security reasons.

However, the Institute was informed that the BNFL Sellafield off-

site emergency plan provides for a detailed emergency planning

zone (DEPZ) out to 2 km from the site boundary, within which

detailed plans must be prepared for evacuation of the population.

Using this information, the Institute was able to estimate the

source term for the accident and to make an assessment of the

potential consequences for Ireland of an accident at BNFL

Sellafield consistent with a 2 km DEPZ.

The assessment assumes that the wind direction was such that

radioactivity released to the atmosphere at Sellafield is carried

directly across Ireland. It shows that the potential contamination

levels in Ireland that could result from such an accident are orders

of magnitude below that at which the implementation of

“immediate countermeasures” such as evacuation or sheltering

would be warranted in Ireland. However, regarding foodstuffs

countermeasures, the assessment undertaken demonstrates that

the BNFL Sellafield reference accident could result in levels of

contamination in the food chain that would require intervention

from the Irish authorities. The changing situation at BNFL

Sellafield, as well as other UK nuclear sites, is monitored on an

ongoing basis by the RPII. Advice in relation to emergency

preparedness arrangements, including the implementation of

countermeasures, is updated as necessary.

From an Irish perspective it is vital that, in the event of an

emergency, procedures are in place to provide Irish authorities

with adequate information in real time. Notification arrangements

have been tested in a recent bilateral exercise and have been

Report of the RPII Visit to BNFL Sellafield 15

shown to work well. In December 2004, an Agreement was signed

on behalf of the Governments of Ireland and the UK which

ensures both countries will cooperate fully in the event of a

significant nuclear incident. The Agreement provides for rapid

exchange of information between the parties and for the regular

testing of these arrangement. The UK has also recently facilitated

direct access for Ireland to its RIMNET (Radioactive Incident

Monitoring Network) system. RIMNET comprises 92 monitoring

sites located around the UK and the network supplies routine

hourly readings and raises an alert if any abnormal increases in the

level of radioactivity are noted. Access to this system is on a real

time basis and is managed in Ireland by the RPII. The RPII

considers that access to RIMNET is useful and welcomes the

initiative from the UK to make it available.

5.4 Terrorist ThreatsNuclear fuel reprocessing by its nature gives rise to the generation

of large inventories of radioactive material, much of which is in a

readily dispersible physical form. Nuclear reprocessing plants such

as BNFL Sellafield, therefore, include a number of facilities holding

inventories of readily dispersible radioactive materials likely to

constitute potential terrorist targets.

The HASTs have long been identified as an issue of particular

concern in Ireland given their radioactive inventory and the fact

that the waste is stored as a liquid. Since the events of 11

September 2001, greater consideration has been given to the

possibility of a HAST failure caused by a malicious incident. The

NII has repeatedly assured the Institute that it is satisfied that the

HASTs have a very high level of protection both in terms of

engineered safety systems and physical security. However, for

security reasons, it is not possible for the NII to share detailed

information with the Institute to allow it to make its own

assessment of the likely consequences for Ireland of a terrorist

attack on the HASTs.

There is a well-established and internationally accepted framework

for accessing the safety of nuclear installations with respect to

“accidental” failures. This framework includes clearly understood

methodologies for assessing risk of failure and places a heavy

dependence on peer review to assess the adequacy of safety

arrangements. The situation with regard to emergencies resulting

from malicious or terrorist incidents is significantly different. Here

there is no widely accepted and transparent methodology for

assessing risks or consequences of an event resulting from a

terrorist attack. Furthermore, the necessity to protect information

from falling into the wrong hands means that such security

systems are not subject to public peer review. The scope and

extent of the terrorist threat assessments undertaken for BNFL

Sellafield are not known. No information on any such assessment

is available in the public domain.

In accordance with International Atomic Energy Agency (IAEA)

guidance7, States should develop a Design Basis Threat (DBT)

from an evaluation of the threat of unauthorised removal of

nuclear material and of sabotage of nuclear material and nuclear

facilities. In the UK the DBT is drawn up by the Office for Civil

Nuclear Security (OCNS). The design basis threat sets out the

forms of possible attack against which nuclear sites should protect

themselves. Measures taken by operators in relation to the design

basis threat are subject to regulatory scrutiny but details of the

measures and of their scrutiny by regulators are classified.

While accepting fully the need to protect sensitive information

about plant security, the lack of an established framework for

assessing the adequacy of threat assessments and security

arrangements remains a significant concern.

7 The Physical Protection of Nuclear Material and Nuclear Facilities,INFCIRC/225/Rev.4

Report of the RPII Visit to BNFL Sellafield16

6. References

CoRWM (2004) Preliminary Report on the Inventory. CoRWM

Document 542. Committee on Radioactive Waste Management.

www.corwm.org.uk/PDF/Inventory.pdf

DEFRA (2001) Managing Radioactive Waste Safely. Proposals for

developing a policy for managing solid radioactive waste in the

UK. Department for Environment, Food and Rural Affairs.

www.defra.gov.uk/environment/consult/radwaste/default.htm

DEFRA (2002) UK Strategy for Radioactive Discharges, 2001-

2020. Department for Environment, Food and Rural Affairs.

www.defra.gov.uk/environment

/radioactivity/discharge/strategy/index.htm

DTI (2002) Managing the Nuclear Legacy. A Strategy for Action.

Department of Trade and Industry.

www.dti.gov.uk/nuclearcleanup/pdfs/whitepaper.pdf

DTI (2004) Civil Nuclear Emergency Planning Consolidated

Guidance. Department of Trade and Industry.

www.dti.gov.uk/energy/nuclear/safety/neplg_guide.shtml

HSE (1990) Outline Emergency Planning for Licensed Nuclear

Power Stations. Health and Safety Executive.

HSE (2000a) The Storage of Liquid High-level Waste at BNFL

Sellafield: A Report by HM Nuclear Installations Inspectorate.

Health and Safety Executive. www.hse.gov.uk/nsd/bnfl.pdf

HSE (2000b) HSE Team Inspection of the Control and Supervision

of Operations at BNFL’s Sellafield Site. Health and Safety

Executive. www.hse.gov.uk/nsd/team.htm

HSE (2001) The Storage of Liquid High-level Waste at BNFL

Sellafield: Addendum to February 2000 Report. Health and Safety

Executive. www.hse.gov.uk/nsd/bnfl2.pdf

HSE (2002) A Guide to the Radiation (Emergency Preparedness

and Public Information) Regulations 2001. Health and Safety

Executive. www.hse.gov.uk/radiation/ionising/reppir.htm

HSE (2005) HMNII’s 2004 Biennial Review of the Storage of Liquid

High Level Waste at Sellafield. Annex to Sellafield and Drigg LLC

Report for Oct-Dec 2004. Health and Safety Executive.

www.hse.gov.uk/nsd/llc/2004/sella4.htm

NDA (2004) NDA Annual Plan. Draft for Consultation. Document

URN04/2009. Nuclear Decommissioning Authority.

www.nda.gov.uk

NRPB (1997) Application of Emergency Reference Levels of Dose

in Emergency Planning and Response. Documents of the NRPB,

Vol. 8, No 1. National Radiological Protection Board.

OSPAR (1998) OSPAR Strategy with regard to Radioactive

Substances. The Convention for the Protection of the Marine

Environment of the North-East Atlantic (OSPAR Convention).

www.ospar.org

RSA (1993) Radioactive Substances Act (c. 12). ISBN

0105412937. The Stationary Office Ltd., London.

www.hmso.gov.uk/acts/acts1993/Ukpga_19930012_en_1.htm

RWMAC (2000) RWMAC’s Advice to Ministers on the

Radioactive Waste Implications of Reprocessing. Radioactive

Waste Management Advisory Committee.

www.defra.gov.uk/rwmac/reports/reprocess/index.htm

Travis, M. (2003) Decommissioning a Spent Fuel Storage Pond

and Decanning Facility. Nuclear Engineer 44(2) p. 55-57.

Turvey, F.J. and Hone, C. (2000) Storage of Liquid High-Level

Waste at Sellafield. An Examination of Safety Documentation.

Radiological Protection Institute of Ireland. www.rpii.ie/reports

Report of the RPII Visit to BNFL Sellafield 17

Annex 1Regulation of Activities at BNFL Sellafield by the Health and Safety Executive’s Nuclear Installations Inspectorate

A1.1 IntroductionThe Nuclear Installations Inspectorate (NII), which forms part of

the UK Health and Safety Executive (HSE), licenses the BNFL

Sellafield site, in common with other UK nuclear installations,

under the Nuclear Installations Act, 1965 (as amended). The

parent Government Department to HSE is the Department of

Work and Pensions but this Department has no role in the

promotion of nuclear energy.

The licensed site includes all the territory and buildings within the

perimeter fence and the licence covers all activities at BNFL

Sellafield involving nuclear and radioactive materials, other than

discharges to the environment which are regulated by the

Environment Agency (EA).

There is a Memorandum of Understanding in place between the

NII and EA as close liaison between these two regulators is

essential if there is to be a coherent approach to radiation

protection of workers and the general public.

The HSE publishes reports of all NII examinations of activities at its

licensed sites as well as quarterly reports for local liaison committees

and quarterly reports of incidents at nuclear installations.

A1.2 Licensing SystemUnlike the licensing systems in many countries where licenses are

valid for a fixed period and where applications for renewal must

be supported by evidence that the licensee remains fit to hold a

licence, in the UK licences for nuclear sites remain in force until all

activities covered by the licence cease and all facilities on the site

have been decommissioned. The continued acceptability of the

practices in which the licensee is engaged is reviewed at specified

intervals, e.g. biennially, quinquennially and, particularly

thoroughly, every ten years.

The review system is applied most rigorously to nuclear power

plants which incorporate life limiting components, for example the

steel reactor pressure vessel in early Magnox reactors which

degrades over time due to neutron embrittlement. However they

are also applied at BNFL Sellafield and other nuclear sites. For

example in the case of Sellafield, considerable work has been

done by BNFL to satisfy the NII that the integrity of the concrete

biological shields on the HASTs and of the stainless steel of the

HASTs themselves, can be guaranteed for the remaining lifetime

of the HASTs. As discussed below, the NII has a number of legal

instruments at its disposal to force licensees to suspend or modify

practices which are covered by the licence.

A1.3 Licence ConditionsThere are 36 standard conditions attached to each licence. The

conditions, which are the same for all nuclear sites, are general

rather than prescriptive in nature. They refer, for example to

making adequate arrangements for bringing and storing nuclear

material on the site (condition 4). The arrangements made by the

licensee must be submitted to the NII for approval.

Of particular interest is condition 36 on the Control of

Organisational Change. This condition obliges the licensee to

make and implement adequate arrangements to control any

change to its organisational structure which may affect safety and

to submit these arrangements to the NII for approval before

implementing them. This condition was introduced in answer to

NII concerns that staffing structures at a number of nuclear

facilities, including in particular Sellafield, were being allowed to

change in a manner which was potentially deleterious to safety. It

was introduced in the summer of 1999 and came into full force in

April 2000, i.e. shortly after the Team Inspection of February 2000,

referred to in section A1.7.

Authorisations permitting change are issued in the form of a

Licence Instrument.

A1.4 Safety CasesThe licensee must prepare Safety Cases for operations on the site

and, where required, submit them to NII for its assessment. Safety

Cases are assessed against the NII’s Safety Assessment Principles

(SAPs) that, in turn, make use of a concept known as Tolerability of

Risk (ToR). This concept postulates three levels of risks. These are

risks that are broadly speaking intolerable, risks that, while

tolerable, should be reduced further if it is practicable to do so

(the As Low As Reasonably Practicable, or ALARP, principle) and

risks that are so trivial that expenditure on reducing them further

would not be justified. The SAPs also refer to probability of

occurrence. For example an accident scenario with very severe

consequences may be considered tolerable if the licensee can

Report of the RPII Visit to BNFL Sellafield18

satisfy the NII that the probability of occurrence is extremely low,

i.e. typically less than one in a million per year.

The Safety Case must also satisfy the NII that all plant and component

failures, which could impinge on safety, have been considered and

that the Probabilistic Safety Assessment, which is used to calculate

risks, is based on realistic estimates of plant and component failures

and on the significance of these failures for safety.

The Safety Case of most direct relevance to the RPII visit is the

Continued Operation Safety Report (COSR) for the HASTs. This

report, which was the subject of an examination by RPII officials, is

discussed in section 3.4.

A1.5 Alterations to the SiteSignificant alterations to the licensed site require prior approval by

the NII. These include in particular:

• The construction of new plant;

• Any modifications to the design of plant under construction

which may affect safety;

• The commissioning of new plant and processes; and

• The restarting of operations, which have been suspended or

shutdown for any reason.

In the case of major projects each step of the project requires a

separate authorisation in the form of a Licensing Instrument.

A1.6 EnforcementThe NII makes use of a number of controls derived from licence

conditions. These include giving Consents, Approvals and

Directions. The licence conditions also provide for the use of

Agreements, Notifications and Specifications. These generally act

as enforcement tools in the non-prescriptive nuclear regulatory

regime. NII inspectors may also use their enforcement powers

under the Health and Safety at Work Act, 1974 (HSWA) to issue

Improvement Notices and, in the case of imminent danger,

Prohibition Notices.

Agreements, notifications, and specifications are all legally

binding communications between the NII and the licensee. They

either allow the licensee to carry out an activity or require some

form of action to be taken. To administer these requests/

authorisations, NII has produced a standard form of letter known

as a licence instrument.

NII may bring prosecutions for breaches of HSWA or licence

conditions. NII’s powers are summarised below.

A1.6.1 ConsentsA Consent is required before the licensee can carry out any activity

which is specifically identified in the licence. For example, consent

is required before a reactor is allowed to be started up again

following its periodic shutdown. Before being granted a Consent

the licensee must satisfy the NII that their proposed action is safe

and that all procedures necessary for control are in place.

A1.6.2 ApprovalsAn Approval is used to freeze a licensee’s arrangements. If the NII

so specifies the licensee is required to submit its arrangements and

cannot carry them out until the NII has given its approval. Once

approved, the procedures cannot be changed without the NII’s

agreement, and the procedure itself must be carried out as

specified; failure to do so would infringe the licence condition and

would be an offence. For example, for nuclear power stations the

NII has approved operating rules important to safety in order to

ensure that licensees cannot change these without seeking the

NII’s agreement to the change.

A1.6.3 DirectionsA Direction is issued by the NII when it requires the licensee to

take a particular action. For example, licence condition 31(1) gives

the power to Direct a licensee to shut down any plant, operation

or process. Such a Direction would relate to a matter of major or

immediate safety importance and has been used rarely.

Report of the RPII Visit to BNFL Sellafield 19

A1.6.4 AgreementsAn Agreement issued by the NII allows a licensee, in accordance

with its own arrangements, to proceed with an agreed course of

action. For example licence condition 22 requires a licensee to have

adequate arrangements to control modifications to safety related

plant. Such arrangements will often state that for modifications

which, if inadequately conceived or implemented, there could be

serious nuclear safety implications, the modification cannot be

carried out without the agreement of the NII. Hence, the licensee

submits a Safety Case justifying the modification and does not

proceed until the NII has written agreeing to this proposal.

A1.6.5 NotificationThe standard licence gives the NII powers to request the

submission of information by notifying the licensee of the

requirement. For example in licence condition 21(8) the licensee

shall, if notified by the NII, submit a Safety Case and shall not

commence operation of the relevant plant or process without the

consent of the NII.

A1.6.6 SpecificationThe standard licence gives the NII discretionary controls with

regard to a licensee’s arrangements and these are implemented

through Specifications. For example, under licence condition

23(2), if the NII so specifies, the licensee is required to refer

operating rules to its nuclear safety committee for consideration.

A1.7 Inspections and ReportsThe NII operates a comprehensive inspection programme. A site

inspector, who is responsible for coordinating inspections, is

designated to each nuclear site. In the case of BNFL Sellafield

some 500 days of inspectors’ time per year are assigned.

In addition to routine inspections, the NII carries out inspections

focused on particular activities at BNFL Sellafield. In September

1999 the NII carried out a team examination of the control and

supervision of operations on the site. This identified shortcomings

pertaining to safety in management systems, organisational

structures, inadequate resources and independent audits. The

report of this visit (HSE, 2000b), published in February 2000,

included 28 recommendations to address these issues. These have

now been closed out to the satisfaction of the NII.

Another NII report of particular relevance to the visit is the

February 2000 report on the storage of liquid high-level waste

(HSE, 2000a). This is a comprehensive review of safety issues

relating to the storage of HLW at BNFL Sellafield. The report

focuses on the integrity of the cooling systems which are required

to prevent the contents of the tanks from boiling and the need to

reduce the stored contents through vitrification. The report

includes 22 recommendations relating to these issues. It should be

noted that the main issues of concern referred to in the NII report

are the same as those highlighted in the RPII report already

referred to in section 3.4.

Report of the RPII Visit to BNFL Sellafield20

In August 2001 NII published an addendum to the February report

which found that all 22 recommendations had essentially been

closed out by January 2001, subject to an ongoing programme of

work. This ongoing programme of work included, in particular,

making the plant more resistant to severe seismic events and by

implication certain forms of terrorist attacks.

A1.8 Implications of BNFL Restructuring for theRegulatory ProcessBNFL is in the process of restructuring in readiness for the

commencement of the Nuclear Decommissioning Authority (NDA)

operation on 1 April 2005. One of the implications is that BNFL, as

presently constituted, will be restructured to form separate

companies that will tender to provide decommissioning services of

one kind or another. The NII will need to be satisfied that the

restructured entity is a viable licensee in terms of its ability to

comply with the NII’s safety requirements.

The NII is also expected to insist that, in order to ensure a

coherent approach to site safety, certain activities involving the

clean-up of legacy wastes and commercial activities i.e. the

reprocessing of spent fuel in THORP and the production of MOX

fuel be carried out under one licence.

BNFL is currently providing the NII with a suite of documents

justifying the proposed change. If, following a perusal of these

documents and a number of inspections to assess readiness for

the proposed changes, NII is satisfied with the planned

restructuring, a licence Instrument will be issued on the 31 March

2005 allowing the restructuring to take place.

A1.9 NII In-house ProceduresThe NII has an ongoing in-house programme of self-assessment

and benchmarking. This includes, in particular, providing the

Nuclear Safety Advisory Committee of the UK Health and Safety

Commission with the terms of reference for a review study of its

SAPs. It also benchmarks its SAPs and Technical Assessment

Guides (TAGs) against the IAEA Safety Standards, Fundamentals,

Requirements and Guides and has a programme to revise them

where the need for revision is indicated.

Report of the RPII Visit to BNFL Sellafield 21

Annex 2Regulation of Activities at BNFL Sellafield by the Environment Agency

A2.1 IntroductionThe Environment Agency regulates the disposal of radioactive

waste to land, sea and air from all nuclear sites in England and

Wales (including the BNFL Sellafield site) by means of

authorisations issued under the Radioactive Substances Acts,

1993. The Environment Agency consults the NII on matters

affecting the exposure of workers and the risk of accidents, in

accordance with NII’s role as a statutory consultee. The nuclear

regulatory work of the Environment Agency (EA) is funded partly

by grant-in-aid and partly by direct charging. In total, forty EA staff

are assigned to nuclear regulation, of which 19 are site inspectors.

On average, site inspectors spend 40% of their time on site. The

EA’s nuclear site regulators are structured into two teams, North

and South. The EA’s Radioactive Substances Regulation (RSR)

Process Group defines how regulatory policy, as set out by the EA

RSR Policy Team, is implemented by the site regulators.

The EA’s regulatory regime covers policy, process and operations

with regard to discharges from the BNFL Sellafield site and it

operates within a legal and policy framework, governed by:

• The Environment Act, 1995;

• The Radioactive Substances Act, 1993 (RSA, 93);

• Government objectives for the EA;

• The UK Strategy for Radioactive Discharges, 2001-2020

(DEFRA, 2002);

• EU directives and international commitments;

• Memoranda of Understanding with the Nuclear Installations

Inspectorate, the Food Standards Agency, the Scottish

Environment Protection Agency and the Nuclear

Decommissioning Authority (currently being drafted); and

• Sector Plan: The EA is setting up partnerships with different

industry sectors to set out what measures it is introducing on

the environment and what its objectives are to reduce

environmental impacts.

The Radioactive Substances Act states that UK Government

Ministers have the right to intervene in EA decisions. The EA

sends all its decisions to Ministers so that they may decide

whether or not to use their powers of intervention.

The EA issues Certificates of Authorisation, under the provisions of

section 13 of the RSA 93, which permit the disposal of specified

radioactive wastes from a specified site, subject to limitations and

conditions. The BNFL Sellafield Certificate of Authorisation

comprises a signed certificate together with nine schedules.

Schedule 1 contains general conditions that are applicable to all

authorised waste types. Schedule 2 specifies the categories of

radioactive waste and the disposal routes that are authorised.

Schedules 3 to 8 include limitations and conditions on the

radionuclides in the waste and the physical nature of the waste

streams. Schedule 9 specifies information to be supplied by the

licensee, in this case BNFL plc, and improvements to be carried out.

The main practices to which the BNFL Sellafield certificate

relates are:

• Reprocessing of Magnox spent fuel;

• Reprocessing of oxide spent fuel (THORP);

• Processing of historic liquid wastes;

• Solid waste storage/retrieval;

• Decommissioning of redundant plant;

• (Decommissioning of) Calder Hall nuclear power station; and

• Research and development.

A2.2 New Certificate of Authorisation for Radioactive Discharges from the BNFL Sellafield SiteIn 1999 the UK Government asked the Environment Agency to

carry out a review of the authorisations at the BNFL Sellafield site.

Following a consultation period, a draft document outlining the

EA’s decisions was published in August 2002. The document was

submitted to the Secretary of State for Health and the Secretary of

State for Environment, Food and Rural Affairs. This decision

document was revised in 2004 to reflect both consultation and the

fact that there had been some major developments since the

decisions were first issued (most notably, the closure of the Calder

Hall reactors). A separate ‘fast track’ review of the regulation of

technetium-99 liquid discharges into the sea from BNFL Sellafield

was also undertaken. The steps involved in these reviews are

outlined in Table 1.

Report of the RPII Visit to BNFL Sellafield22

The EA’s stated objectives of the reviews were to ensure that

prescribed limits and conditions are appropriate, that disposal

represents the Best Practicable Environmental Option (BPEO), that

Best Practicable Means (BPM) are used to minimise waste

discharges and that radiation doses to the public are kept ‘As Low

As Reasonably Achievable’ (ALARA) and remain within the legal

limits and constraints. In developing the new authorisation, the EA

carried out an examination of the existing framework of discharge

limits and the numerical values of individual limits, to assess

whether or not any changes were appropriate for the future

regulation of waste discharges from the site.

The main features of the new authorisation are:

• A new integrated authorisation to replace the six previous

authorisations.

• Updated discharge limits: Reductions in the ‘headroom’ (i.e.

gaps between the expected/typical discharges and the

discharge limits authorised) and reductions in 14 site limits for

discharge to air and 8 site limits for discharge to sea.

• Removal of two aerial discharge limits (argon-41 and sulphur-

35) as a result of the shut-down of the Calder Hall reactors.

• More limits on discharges from individual plants as well as

from the site as a whole.

• Introduction of throughput related limits for Magnox and

THORP.

• Introduction of new conditions requiring BPEO/BPM8 to be

used to control discharges. In addition, a programme of

process and environmental improvements and research are

outlined in the authorisation.

• New conditions requiring BNFL to have management systems,

organisational structures and resources to achieve compliance

with the authorisation.

Table 1Timeline of Review and Issue of BNFL Sellafield Discharge Authorisations

Date New (Main) Authorisation Technetium-99 Authorisation

July 2000 Scope and Methodology published

after public comment

November 2000 Consultation on Technetium-99 proposals

July 2001 Consultation on proposals

September 2001 Proposed Decision on Technetium-99

August 2002 Proposed decision

December 2002 Ministers’ Decision

July 2003 MAC diversion

March 2004 Ministers’ consent to proceed

April 2004 TPP implemented

August 2004 Authorisation issued (following update and

consultation with HSE/NII and FSA)

October 2004 Authorisation came into force

8 BPEO: Best Practicable Environmental Option – the best option for disposal ofradioactive waste (based on environmental impact)BPM: Best Practicable Means - minimising of discharges once the BPEO route hasbeen chosen (“optimisation”)

Report of the RPII Visit to BNFL Sellafield 23

A2.3 An Integrated Authorisation for Regulating Radioactive Waste Disposals fromBNFL SellafieldThe EA is introducing integrated certificates of authorisation for

the disposal of radioactive waste from nuclear sites. In contrast to

previous certificates of authorisation, which related to disposal

either to land, water or air, an integrated certificate of authorisation

specifies the general conditions that apply to all disposal routes. It

also specifies the limitations and conditions that apply to individual

disposal routes. One of the EA’s stated aims is improved alignment

with the approach to regulating the discharge of other pollutants.

Prior to the issuing of the new authorisation in October 2004,

there were six authorisations covering the BNFL Sellafield site:

• Discharges to air

• Discharges to sea

• Incineration of oil

• Disposal of solid LLW to Drigg

• Disposal of LLW to BNFL Sellafield

• Transfer of waste from BNFL Sellafield to other BNFL and

UKAEA sites

Under the new authorisation issued, these six authorisations have

been integrated into a single (multi-media) authorisation which

includes: standard general conditions which are consistent across

the nuclear industry including the use of BPEO/BPM; new

conditions covering the management, organisation and resources

of BNFL; a revised framework of discharge limits; and a number of

proposed discharge reduction schemes.

A2.3.1 Limits and Advisory Levels in the New AuthorisationThe current authorisations require BNFL to submit annual reports

to the Agency on the progress that has been made in research

and development for achieving a continuing reduction in

radioactive discharges.

The previous BNFL Sellafield authorisations contained the

following range of limits and advisory/notification levels:

a. 12 month rolling (annual) limits for site discharges;

b. Annual limits for plants or groups of plants (i.e. schedules

containing limits for groups of stacks);

c. Additional components to annual limits for a small number of

specific plants;

d. Short-term limits (monthly, weekly and daily);

e. Plant throughput limits for THORP aerial and liquid discharges;

f. Calendar year limits for solid waste disposals to Drigg;

g. Radionuclide concentration limits for on site solid waste

disposals; and

h. Quarterly notification levels for aerial and liquid discharges.

In the new authorisation, the following changes were introduced:

a. Site annual discharge limits will be expanded to cover all

radionuclide discharges, which meet defined criteria9.

b. Annual discharge limits set at a plant level, rather than group

of plants, wherever practicable and where plant radionuclide

discharges meet the defined criteria.

c. The additional components to limits, which allowed increased

discharges in the event of prolonged plant outage, were

removed, wherever deemed practicable.

d. New plant limits were introduced (i.e., controls on discharges

from individual plants as well as from the overall site).

e. Weekly limits and advisory levels replaced a range of short-

term limits (daily and weekly).

f. Throughput related limits now apply to the Magnox

Reprocessing Plant as well as to THORP and they apply to any

period of 12 consecutive months rather than a calendar year.

g. New limits have been introduced to regulate the transfer of

radioactive waste between BNFL Sellafield and other

nuclear sites.

h. New limits have been introduced to allow the extended use of

on-site solid waste disposal facilities and the previous

provision for in-situ burial of waste on the BNFL Sellafield site

and its associated limits has been revoked.

i. Quarterly notification levels now apply to any 3 month period

rather than a calendar year quarter and are set at 25% of all site

and plant annual discharge limits.

9 The dose to the most exposed group from the established worst case sitedischarges exceeds 1 microsievert (µSv) per year OR the collective dose (world-wide truncated at 500 years) from the established worst case site dischargesexceeds 0.1 manSv per year of discharge OR the quantity of the established worstcase site discharge exceeds 1 gigabecquerel per year (for gaseous discharges) or 1

terabecquerel per year (for aqueous discharges) OR the half-life of theradionuclide exceeds 10 years and the radionuclide is concentrated inenvironmental materials by a factor greater than 1000 OR the discharge will beused as plant performance or process control indicator or for effective regulatorycontrol and enforcement.

Report of the RPII Visit to BNFL Sellafield24

The EA applies the following principles in setting the annual limits

on discharges:

• The limits will be based on the minimum level of discharge the

EA judges that the operator needs to make in order to operate

the plant;

• The limits will provide necessary headroom based on

fluctuations and/or trends in the level of discharge from year

to year, which the Agency judges are an inherent characteristic

of the design of a plant and its operation; and

• The objective is that there should be no unnecessary

headroom when the limits are set.

The previous and new annual limits for discharges to sea and air

are summarised in Table 2.

A2.3.2 Radionuclide-specific Site Disposal LimitsTechnetium-99: Following the implementation of technetium-99

abatement involving addition of the chemical

tetraphenylphosphonium bromide (TPP) in the Enhanced Actinide

Removal Plant, the technetium-99 site limit has been decreased

from 90 terabecquerels (TBq) per year to 20 TBq per year. This

will be further reduced, to 10 TBq per year, once the waste in the

MAC storage tanks has been processed.

Table 2Annual Limits for Discharge from the BNFL Sellafield Site

Radionuclide or

Group of Radionuclides Sea Pipelines (TBq) Aerial (TBq x 10-3)

Previous Limits From October 2004 Previous Limits From October 2004

Tritium (H-3) 30,000 20,000 1,500,000 1,100,000

Carbon-14 21.0 21.0 7300 3300

Cobalt-60 13.0 3.6 0.92 n/a

Strontium-90 48.0 48.0 9.4 0.71

Sulphur-35 n/a n/a 210 n/a

Argon-41 n/a n/a 3,700,000 n/a

Krypton-85 n/a n/a 590,000,000 440,000,000

Zirconium-95 + Niobium-95 9.0 3.8 Not specified Not specified

Technetium-99 90.0 20.0 Not specified Not specified

Ruthenium-106 63.0 63.0 56.0 28.0

Antimony-125 Not specified Not specified 5.0 2.3

Iodine-129 2.0 2.0 70.0 70.0

Iodine-131 Not specified Not specified 55.0 55.0

Caesium-134 6.6 1.6 Not specified Not specified

Caesium-137 75.0 34 18.0 5.8

Cerium-144 8.0 4.0 Not specified Not specified

Neptunium-237 Not specified 1.0 Not specified Not specified

Plutonium (Alpha) 0.7 0.7 1.2 0.19

Plutonium-241 27.0 25.0 17.0 3.0

Americium-241 0.3 0.3 0.74 0.12

Curium-243+244 Not specified 0.069 n/a n/a

Total Alpha 1.0 1.0 2.5 0.88

Total Beta 400 220 340 42.0

Uranium (in kg) 2000 2000 Not specified Not specified

Report of the RPII Visit to BNFL Sellafield 25

Antimony-125: The proposed new site limit for the radionuclide

antimony-125 in liquid discharges has been deferred pending

more information from BNFL. The discharge of antimony-125 will

remain limited by the site limit, and a new plant limit, on total beta

activity and will be subject to the requirements to minimise

discharges through the application of BPM and to a specific

requirement to carry out a programme of work. The introduction

of a site limit for antimony-125 in liquid discharges will be

reviewed before the end of 2007.

Argon-41 and Sulphur-35: The plant and site limits for aerial

discharges of argon-41 and sulphur-35 have been removed in

response to the shut-down of the Calder Hall Power Station.

Liquid discharges of Carbon-14, Strontium-90,

Ruthenium-106, Iodine-129, Plutonium (alpha),

Americium-241, Total Alpha and uranium: The aqueous

discharge limits remain unchanged. In all these cases, BNFL’s

stated business requirements exceed the current limits. The EA

has reviewed BNFL’s estimates of future discharges in the

context of BNFL’s future business plans and considers there is no

scope for reduction in these limits at the current time. With the

exception of carbon-14, the major future source of the aqueous

discharges of these radionuclides is predicted to be the

processing of medium active liquid wastes (medium active

concentrate for strontium-90 and salt evaporator concentrate for

ruthenium-106) and decommissioning work (for the alpha

emitting radionuclides).

Carbon-14: Magnox reprocessing and the storage plant for high

level liquid waste are predicted to be the major future source of

carbon-14 liquid discharges. The installation of a new caustic

scrubber in 2001 to remove carbon-14 from aerial discharges from

the high level waste storage plant has diverted the majority of

carbon-14 from aerial to liquid discharges, resulting in higher

liquid discharges of carbon-14.

Liquid discharges of Hydrogen-3 (Tritium), Cobalt-60,

Zirconium-95/Niobium-95, Caesium-134, Caesium-137,

Cerium-144, Plutonium-241 and Total Beta: The past

performance of the SIXEP plant in removing caesium from liquid

discharges and the reduction in the processing of medium active

concentrate are two of the main reasons why the discharge limits

for these radionuclides have been introduced.

Aerial discharges of Hydrogen-3 (Tritium), Carbon-14,

Krypton-85, and Argon-41: Magnox reprocessing is the

major source of aerial discharges of tritium. The EA considers

that there is scope for a reduction in the current effective site

limit whilst still allowing for a maximum Magnox reprocessing

fuel throughput of 1600 metric tonnes in any 12 month period

and allowing for the possibility of reprocessing higher burn-up

Magnox fuel towards the end of the Magnox reprocessing plant

lifetime. The main source of krypton-85 discharges is the

THORP reprocessing plant. The EA proposed reduction in the

limit, which would still allow for a maximum THORP

reprocessing fuel throughput of 1200 te in any 12-month period

and for the programmed reprocessing of higher burn-up oxide

fuel over the next 7 years.

A2.3.3 Annual Plant Discharge LimitsThe EA has investigated whether it would be practicable for BNFL

to monitor individual plant waste streams and has required BNFL

to provide information including the costs of installing new

monitoring equipment10. Following the investigation, the EA has

decided to require BNFL to report separately the discharges for

each of the main activities on the site. Where appropriate

monitoring arrangements are not in place, discharges will be

estimated indirectly using knowledge of actual operations and

actual discharges where they are measured. In such cases the

assessment methodology must be approved by the EA. This new

reporting procedure comes into operation in June 2006.

Limits are proposed for the individual major discharge stacks across

the BNFL Sellafield site and for the major effluent treatment plants

on the BNFL Sellafield site. While plant limits were previously

specified for aerial discharges from individual stacks, or groups of

stacks11, aqueous plant limits are a new feature of the authorisation.

The sum of the plant limits does not equal the relevant site limits.

This is because site limits are based on the sum of the worst-case

plant discharges, but the plant limits are based on the individual

worst-case plant discharge plus an operating margin.

10 DETR draft Statutory Guidance states: “Monitoring requirements should beframed in such a way as to allow the discharges from each plant, or otherappropriate individual sources for large plant, to be identified separately, and notmerely as aggregated discharge levels”.

11 previously known as schedule limits.

Report of the RPII Visit to BNFL Sellafield26

A2.3.4 BPEO/BPM RequirementsThe authorisation requires BNFL to demonstrate that the best

practicable environmental option has been adopted for the

disposal of all principal waste streams. The demonstration of BPEO

will be a pre-requisite for any waste management strategy that

involves dilution and dispersal of radionuclides in the

environment, where concentration and containment of waste

would be a feasible alternative.

The application of Best Practicable Means (BPM) involves the use of

a level of management and engineering control to minimise as far as

practicable the release of radioactivity to the environment. It takes

account of a range of factors including cost effectiveness,

technological status, operational safety and social and

environmental factors. Under the BPM conditions in the

authorisation, BNFL should take into account a range of factors

including the benefit, cost effectiveness, technological status,

operational safety and social and environmental factors, when

deciding on a waste disposal route or method. In its assessment of

the waste management techniques used at BNFL Sellafield, the EA

takes account of best industry practice and experience in other

countries.

The outcomes of the EA review of its assessment of waste

management techniques in light of BPM/BPEO are summarised

below:

Hydrogen-3 (Tritium): The EA considers that BNFL’s current

practices for disposing of tritium from BNFL Sellafield represent

BPEO. The Agency considers therefore that current practice of

caustic scrubbing of process extract ventilation streams in the

Magnox Reprocessing Plant is consistent with the use of BPM for

minimising tritium discharges to atmosphere. The EA also considers

that caustic scrubbing and chilled water dehumidification of

process extract ventilation streams in THORP is consistent with the

use of BPM for tritium discharge minimisation.

Carbon-14: The EA considers that the current operation of the

carbon-14 (barium carbonate) removal plant in THORP that

results in the radionuclide being trapped in a solid waste-form

and subsequently encapsulated in cement represents BPEO.

However, it remains to be convinced that the current design and

operation of the plant is consistent with the use of BPM for

minimising discharges.

Cobalt-60: The EA considers that the use of an ion exchange pre-

coat on an existing particulate filter in the THORP fuel pond, if

current plant trials are proven to be successful, would represent

BPEO for disposing of cobalt-60 in a solid waste and BPM for

minimising discharges to sea.

Caesium-137: The EA considers that BNFL’s current practice of

converting greater than 99% of caesium-137 in spent fuel into a

solid waste form and storing it to await disposal is consistent with

BPEO. The EA considers that further reductions in caesium-137

discharges to sea could be achieved by routing B27 pond purge

water to SIXEP. The Agency proposes to require BNFL to

implement this abatement option, where reasonably practicable,

rather than discharge the pond purge water via SETP to sea.

Strontium-90: The EA considers that BNFL’s current practice of

converting greater than 99% of strontium-90 in spent fuel into a

solid waste form and storing it to await disposal is consistent with

BPEO. The EA has, however, put forward proposals resulting from

the technetium-99 review that, if implemented, would divert

strontium-90 in future arisings of MAC to vitrification and hence

avoid its discharge to sea. A programme of work is also required,

under Schedule 9, to improve the understanding of the sources of

strontium-90 (and antimony-125) in aqueous discharges from SIXEP.

Iodine-129: The EA considers that the disposal to sea of 90% of

iodine-129 in waste streams arising from spent fuel reprocessing at

BNFL Sellafield is at present consistent with BPEO. However,

around 6% of the iodine-129 discharged to the environment from

BNFL Sellafield is presently in aerial discharges and THORP is the

main source of such discharges. The EA considers iodine–129

discharges may be further reduced by the addition of non-

radioactive iodine to the fuel dissolution process in THORP. The

Agency therefore requires BNFL to provide a programme for

implementing the addition of iodic acid to the fuel dissolution

process in THORP to abate iodine discharges or justify why it is

inappropriate to do so.

Actinides: The EA considers that BNFL’s current practice of

converting greater than 99.9% of plutonium and other actinides

present in waste streams into a solid waste form and storing them

pending final disposal is consistent with BPEO/BPM for disposing

of the radionuclides.

Report of the RPII Visit to BNFL Sellafield 27

A2.3.5 Abatement TechnologiesBNFL’s research and development programme for the abatement

of discharges was reviewed by the EA. The outcome of the review

was that BNFL is required through improvement conditions

(Schedule 9) in the authorisations, to implement further research

and development in specific areas. If the waste reduction schemes

are found to be technically feasible, BNFL is also required to

provide EA with detailed cost/benefit analyses. BNFL may then be

required to introduce measures to improve waste management

arrangements where research and development and the cost-

benefit analysis show the scheme to be effective. Currently, a

number of discharge reduction schemes are being explored.

These include:

1. Ion-exchange to abate cobalt-60 from THORP;

2. The use of iodic acid to reduce iodine-129 gaseous discharges

(this would result in a diversion of iodine-129 to liquid

discharges if implemented);

3. Minimisation of nitrogen-14 fuel impurities which would

reduce carbon-14 discharges;

4. Diversion of borehole 68 groundwater to SIXEP which would

reduce caesium-137 discharges; and

5. Development of a krypton-85 cryogenic abatement plant

(work on this will depend on plans to continue operating

THORP beyond 2016).

Report of the RPII Visit to BNFL Sellafield28

Annex 3Emergency Planning in the UK

A3.1 REPPIRThe Radiation (Emergency Preparedness and Public Information)

Regulations 2001 (REPPIR) implement in Great Britain the articles

on intervention in cases of radiological emergency in Council

Directive 96/29/Euratom (known as the Basic Safety Standards

Directive) and also certain articles of Council Directive

89/618/Euratom (known as the Public Information Directive).

REPPIR establish a framework for radiological protection through

emergency preparedness for radiation accidents with the potential

to affect members of the public, which occur either at fixed

premises or during specified transport operations. The REPPIR

public information provisions require that the public are:

• properly informed and prepared, in advance, about what to do

in the unlikely event of a radiological emergency occurring;

and

• provided with information if a radiation emergency actually

occurs.

The Health and Safety Executive has produced guidance on these

regulations (HSE, 2002).

REPPIR place legal duties on operators of premises where work

with ionising radiation is carried out, transport carriers who convey

radioactive material, local authorities and employers of people

who intervene in a radiation emergency. REPPIR do not replace

existing nuclear site license conditions but operators of licensed

sites who comply with those conditions will satisfy the equivalent

provisions in REPPIR.

A radiation emergency for the purposes of these regulations is an

event that is likely to result in any member of the public receiving

an effective dose of 5 millisievert (mSv) or more during the year

immediately following the emergency. Operators of premises and

transport carriers need to determine whether the regulations will

apply through identification of the quantities of radionuclides or

fissile material used or transported which are then compared with

threshold amounts set out in the Regulations. If the threshold

amounts are exceeded, there may be the potential for a radiation

emergency, and so the Regulations will apply.

The main responsibilities which REPPIR places on operators of

premises and transport carriers who handle or transport radioactive

substances in excess of the threshold quantities, are to:

• carry out an assessment to demonstrate that all hazards that

could cause a radiation accident have been identified and the

risks to employees and others have been evaluated;

• take all reasonably practicable steps to prevent a radiation

accident and limit the consequences of any that do occur; and

• send a report of the assessment to the NII which should

include certain specified information and show whether a

radiation emergency is reasonably foreseeable.

If the assessment concludes that a radiation emergency is

reasonably foreseeable, then operators and carriers must also:

• prepare an emergency plan;

• supply information to the local authority to enable an off-site

emergency plan to be prepared;

• review and test the emergency plan to identify its

effectiveness and ensure it remains up to date;

• implement the emergency plan if a radiation emergency

occurs, or if an event occurs that could lead to a radiation

emergency;

• notify the NII of dose levels for employees who may receive

emergency exposures; and

• provide information to members of the public about what to

do in the event of a radiation emergency.

Report of the RPII Visit to BNFL Sellafield 29

A3.2 UK Framework for Emergency Planningand Response at Civil Nuclear SitesThe Department of Trade and Industry (DTI) has a lead role in

bringing together a wide range of organisations with interests in

off-site civil nuclear emergency planning through the Nuclear

Emergency Planning Liaison Group (NEPLG). This group has

prepared guidelines based on REPPIR for arrangements for

nuclear emergency planning, which are set out in the handbook

“Civil Nuclear Emergency Planning Consolidated Guidance” (DTI,

2004). The handbook covers planning and testing of off-site

emergency preparedness and consolidates all NEPLG guidance

into a single document for general reference by planners and

practitioners concerned with emergency response at civil nuclear

sites. The key aspects of the NEPLG guidance set out in the

handbook are described below.

A3.2.1 Responsibility for Emergency Planning Responsibility for the on-site emergency plan lies with the site

operator, transport emergency plans are the responsibility of the

carrier and off-site plans are the responsibility of the local

authority. Each has the duty to ensure that plans are prepared and

are adequate and fit for purpose. All organisations with a role in

responding to a reasonably foreseeable emergency must be

involved, as appropriate, in the preparation of emergency plans.

The site operator or transport carrier is required to fully resource

all emergency plans. Licence conditions and the Radiation

(Emergency Preparedness and Public Information) Regulations

2001 require nuclear operators and local authorities to ensure on-

site and off-site emergency arrangements are in place.

A3.2.2 Role of the Local AuthorityUnder REPPIR the local authority has responsibility for

preparation, review, revision, testing and implementation of an off-

site plan for any premises in respect of which the operator’s risk

assessment shows that a radiation emergency is reasonably

foreseeable. In addition, the local authority is required to prepare

arrangements to supply information to members of the public in

the event of a radiation emergency actually occurring, regardless

of how it may occur. These arrangements are intended to cover

events such as fallen nuclear-powered satellites, transport

accidents or incidents occurring overseas that may also affect

Great Britain, as well as from premises subject to REPPIR. Local

authorities may also be involved in the dissemination of prior

information to the public from operators and carriers.

It is only since 2002, that off-site planning has been a legal

responsibility on local authorities. Prior to the 2001 Regulations,

local authority participation was on a voluntary basis. There is no

requirement under REPPIR for local authorities to prepare

emergency plans for transport.

A3.2.3 Preparation of Off-site Emergency PlansOff-site emergency plans should provide for rapid and effective

action for accidents that can be reasonably foreseen. Such plans

should be capable of being extended should less likely and more

serious accidents occur. For each licensed site the operator must

define a reference accident upon which detailed off-site

emergency planning can be based. The reference accident must be

based on the concept of the worst credible accident, which is

reasonably foreseeable at that site, taking into account all of the

facilities on the site. Underlying REPPIR is the general principle that

planning must be proportionate and must be related to the risk of

an event occurring and hence planning should not be based on

worst case scenarios, which take no account of the probability of an

event occurring. For each site, a reference accident is defined and

this is the bounding scenario for all facilities on that site.

The operator must, before commencing operations on a site,

submit to the NII for approval details of the reference accident. If

this is accepted by NII it then forms the basis for deciding the size

of the Detailed Emergency Planning Zone (DEPZ) within which

detailed plans must be prepared for implementation of each

applicable countermeasure. It is the role of the NII to determine the

size of the DEPZ for evacuation, sheltering and administration of

stable iodine, where these are applicable. The size of the DEPZ is

generally determined with reference to computer model

predictions of the distances at which the avertable dose would

exceed the National Radiological Protection Board (NRPB)

Emergency Reference Levels (ERLs) (NRPB, 1997). The NII will

then inform the local authority in whose functional area the site is

located the countermeasures for which it must prepare detailed

implementation plans for and the size of the DEPZ for each of those

countermeasures.

Report of the RPII Visit to BNFL Sellafield30

The off-site plan should bring together the emergency

arrangements of all the agencies with a role to play in the

intervention of a radiation emergency occurring at the premises.

The plan provides a framework for a multi-agency response. These

agencies would normally include the police, fire services,

ambulance service, director of public health, County Council,

Borough Council, Government Technical Adviser (GTA), NII,

NRPB, FSA, EA, water utility, DTI and DEFRA.

As part of the off-site emergency plan, the local authority must

designate an off-site facility (OSF) from which the emergency

response is managed and coordinated. Locally the OSF is known

by different titles such as local emergency centre, off-site centre or

district control centre. This is a strategic centre, where during the

emergency phase the activities of all responding organisations are

coordinated. In as far as practicable each of responding

organisations will have a representative at the OSF during the

emergency phase. This representative will normally have a support

team in place and will have access to the necessary

communication facilities.

A3.2.4 Role of PoliceThe police are tasked with chairing the coordinating group

meetings, which involve a representative drawn from all of the key

organisations with a role in the response and where decisions are

made on actions to protect the public. This group meets at the off-

site centre and is normally chaired by a local police assistant chief

constable. The police are also tasked with arranging for

information and advice to be passed on to the public via the media

briefing centre.

A3.2.5 Role of the GTACentral Government is represented at the off site centre by the

GTA, who is appointed by the Secretary of State for Trade and

Industry or the Scottish Ministers. The role of the GTA is to

provide independent and authoritative advice to the police and

other authorities handling the off-site response on the measures

they should take to deal with the emergency. It is also the role of

the GTA to provide an authoritative response to the media on

behalf of Government at local media briefings.

A3.2.6 Role of the NIIThe NII is expected to respond to a range of unplanned nuclear

events on or off nuclear sites. The NII’s regulatory role is primarily

that of witnessing, monitoring and recording the operator’s

responses to the event. On-site the operator is responsible for

taking corrective actions in an emergency. It is not part of the NII’s

responsibility to determine what action should be taken; however,

under certain circumstances the NII may offer advice. It is

considered most unlikely that the NII would contemplate the use

of enforcement powers during an emergency and if this were to

happen it would only be done under very unusual circumstances

and with the authority of the Chief Inspector.

A3.2.7 ExtendibilityGeneral non-site-specific contingency plans of local authorities

exist to deal with a range of civil emergencies from industrial

accidents to natural disasters such as flooding. In considering

whether, and to what extent, these need to be enhanced to deal

with emergencies at nuclear sites larger than the reference

accident the NEPLG guidance states that “….a balance needs to be

struck between ensuring that plans are sufficiently extensive to

cope with serious emergencies, and avoiding a waste of resources

that could occur through over-planning for most improbable

emergencies.” NEPLG guidance specifies that emergency plans

should provide the basis for dealing with radiation emergencies

that are not reasonably foreseeable through the concept of

extendibility, whereby arrangements made for the DEPZ can be

extended over a greater area.

Responsibility for determining the extent and nature of

extendibility planning around a civil nuclear site rests with the local

authority and other relevant emergency response organisations in

consultation with the site operator. NEPLG, however, recommends

that planners take account of the hypothetical extended release

scenario, as set out by the NII (HSE, 1990). This scenario requires

consideration of sheltering and administration of stable iodine

tablets out to approximately 15 km and evacuation out to 4 km.

Report of the RPII Visit to BNFL Sellafield 31

A3.2.8 ExercisesThree levels of exercise are required by the NII. Level 1

exercises involve a scenario requiring only an on-site response

and must be conducted every year at each site. Level 2

exercises test off-site response and must be conducted at each

site every 3 years. Typically there are twelve level 2 exercises

per year in the UK. Level 3 exercises are intended to test

national arrangements and each year one level 2 exercise is

designated as the annual level 3 exercise.

A3.2.9 Response to Far-field ImpactsThe framework for coordinated action to mitigate any impact from

a nuclear accident beyond 40 km from the site is the Department

for Environment, Food & Rural Affairs (DEFRA) plan for “Response

to Radiological Emergencies”. This general contingency plan was

published in 1988 to deal with the consequences for the UK of

overseas nuclear accidents. However, these measures would also

apply to far field impacts from an accident taking place in the UK.

Emergency planning guidance has also been issued by the

Department of Trade and Industry (DTI, 2004).

Report of the RPII Visit to BNFL Sellafield32

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