submission to: nuclear fuel cycle royal commission, south...
TRANSCRIPT
(
Submission to:
Nuclear Fuel Cycle Royal Commission, South Australia, Australia
Response to Issue Four: Management, Storage and Disposal of Nuclear and
Radioactive Waste.
This Submission #3 Radioactive Waste - its management and disposal in
South Australia is made by:
Dr lan J Duncan FTSE
Radioactive Waste- its management and disposal in South Australia
Table of contents:
1. Introduction
2. Wastes from each step in the Nuclear Fuel Cycle (NFC}
3. Pangea Resources
4. Radioactive Wast es generated by a typical Nuclear Power Plant (NPP)
5. The Scandinavian method of High Level Waste management.
6. Conclusion
At tachment A: Thesis Chapter 2: Radioactive Waste
Extracted from Doctoral Thesis, University of Oxford 2001: "Radioactive Waste: Risk, Reward, Space
and Time Dynamics" . An Abstract of the Thesis is attached to I an J Duncan Submission #1 to Nuclear
fuel Cycle Royal Commission, South Australia.
Radioactive Waste - its management and disposal in South Australia
1. Introduction
As the Royal Commission addresses topics associated with the Nuclear Fuel Cycle it will find
that most proposed projects will generate radioactive waste and therefore must illustrate its management and disposal. There is a large technical component to the subject of radioactive waste and a societal concern about its safe handling and disposal. There is also
a measure of distrust by a majority of the public, particularly if a government body or scientist working alone 'declares' a solution to such waste disposals. The author's Research
and Doctoral Thesis at the University of Oxford addresses many issues in the field of Society and the disposal of radioactive waste. A copy of the Thesis is held in the Library of ANSTO
and can be made available to the Royal Commission if so required.
Attachment A: Thesis Chapter 2: Radioactive Waste sets out elements of radioactive waste generation, management and disposal and concludes that: "There is the realisation that any final disposal method must allow for the concept that ultimately all of society's waste is diluted and dispersed into its near field . The disposal mechanism must provide the time necessary to allow for that which is 'concentrated and contained' to be altered and dispersed into its environment without hazard to the biosphere- the result of a truly dynamic process bounded by space and time." This philosophy applies to all other intractable wastes.
The disposal of radioactive waste has a moral dimension and I believe it to be 'that each country must provide for the safe disposal of radioactive waste that it generates'. These wastes will clearly arise from nuclear power generation but in lesser amounts will also arise from radio-pharmaceutical production; applied medical therapy; scientific research and industry processes. Radioactive waste is part of a broader spectrum of 'intractable wastes' and each Australian State has a responsibility to manage and dispose of these- some States are more advanced than others. An example is the Western Australia State Government's Mount Walton East Intractable Waste Depository in the Yilgarn area of WA. This operating facility accepts chemical and Low Level Radioactive Waste. See: https://www.finance.wa.gov.au/cms/Building Management and Works/Regional Programs/Specia I Projects.aspx
Most nuclear power countries have failed to live up to expectation when it comes to the disposal of its radioactive wastes. At the same time it may not currently be a hazard to the existing biosphere but has that latent possibility. The United Kingdom is typical of many countries as their specialist companies BNFL (http://en.wikipedia.org/wiki/BNFL) and Nirex (http://en.wikipedia.org/wiki/Nirex) have been disenfranchised leaving the problem to a further set of Governmental entities.
One of the leaders in radioactive waste management is Finland. The author can introduce the Commission to Posiva Oy (http://www.posiva.fi/en ) if required. If the Commission is contemplating visiting elements of the Western World nuclear industry such an itinerary should include the works and offices of Posiva at Olkiluoto and Eurojoki in Western Finland. Posiva currently operates Low Level and Intermediate Level Waste repositories underground in granite formations at Okiluoto1
. It currently has community acceptance and is well advanced in the testing of a geological formation in the Eurojoki region that could ultimately receive Spent Nuclear Fuel (SNF) as a HLW waste.
[Okiluoto1 site also hosts two operating Boiling Water Reactors (BWR) owned and operated by TVO, the larger Finish power utility. It is also the site of a NPP under construction, Areva' s Okiluoto #3 EPR 1600- much delayed and over spent]
2
Also in Scandinavia, SKB- Swedish Nuclear Fuel and Waste Management Co has successfully operated the Clab underground rock laboratory near Oskarsham. This and its nearby reactor site could also be worth a visit. http://www.skb.se/default __ 24417.aspx
As with most States, Western Australia has legislation that prevents the absorption of other States' intractable waste into its operating Mount Walton East repository. This runs contra to the concept that it is each country that is responsible for its waste and therefore one facility could absorb all States' waste. South Australia therefore must look to the management and ultimate disposal of all of its intractable waste as a country-wide repository in some other state cannot be relied on. However SA, by amending legislation, could provide for the receipt of its own and selectively other States' waste. Perhaps there could be a mid-sized intractable waste storage and disposal repository in a remote area of SA that makes this undertaking.
South Australian legislation which currently prevents receipt of intractable waste of other States or Countries was put in place by the Rann Government NUCLEAR WASTE STORAGE FACILITY (PROHIBITION) ACT 2000 No. 68 of 2000 [Assented to 30 November 2000) [http://wwwS.austlii.edu.au/au/legis/sa/num act/nwsfa68o2000476/nwsfa68o2000476.pdf ) as a means to block the threat of imported multinational High Level Waste as envisaged by Pangea Resources. http://en.wikipedia.org/wiki/Pangea Resources. Whilst the legislation showed an element of political expediency the decision, in the author's opinion, lacked the element of 'Statesmanship'. Would it have been better to leave open the matter of receiving other Australian State's intractable wastes? An Intractable Waste Repository could be sited in a remote area of South Australia; generate revenue and create work for South Australians. Perhaps the political catch phrase could have been "South Australia, the State that cleaned up Australia" I
The current work of the Commonwealth Government Department of Industry and Science National Radioactive Waste Management Facility (NRWNF) which will lead to a site for LLW disposal and perhaps the interim storage of ILW may involve any of the States or Territories. For an update on the siting process and outcome perhaps the Commission should make contact with Mr Michael Sheldrick, General Manager, Resources Division, Department of Industry, [email protected] . The author is a member of the Independent Advisory Panel for NRWNF and is bound by confidentiality until the selection process is complete and announced by the Minister.
If South Australia wishes to go ahead with any element of nuclear activities it will need to provide a repository for the waste generated. Any State could undertake this opportunity if it wished to but South Australia cannot rely on that outcome and therefore will need to include waste management and disposal in its remit. Fortunately South Australia does have sparse population in parts and the geological space necessary for this task.
2. Wastes from each step in the Nuclear Fuel Cycle
For reference, a list of the intractable wastes (Table 1) that might accrue for each step in the nuclear fuel cycle follows. The World Nuclear Association Library data bank also covers the topic more expansively. It will be important that any proponent of a uranium processing step provides a clear understanding of the wastes that will be generated; waste management and disposal for each specific waste. See WNA Waste management Overview:
http://www.world-nuclear.org/info/Nuclear-Fuei-Cycle/Nuclear-Wastes/Waste-ManagementOverview/
3
Table 1. List of Intractable Wastes from the Nuclear Fuel Cycle
Process Waste type Classification
Mining and uranium extraction Waste rock, Tailings Low level, long lived. Tailings
are often reworked in the
future to recover more of the
economic minerals.
Conversion from impure U30 8 Tailing of impurities, perhaps Low level, long lived
concentrate from mines to pure trace of U.
UFG.
Enrichment of the U235 Considerable quantities of Small amounts can be used in
component of the natural UF6 depleted uranium (DU, natural dilution of weapons grade
to say 5% U235• The isotopic level of U235 reduced) in UF6 material for civil NPP fuel,
ratio in natural occurring form. Requires specific ballistics and for fast neutron
uranium is 99% U238, packaging and storage. reactor fuel. However there
0.711% U235• will be an accumulation of DU.
Fuel fabrication Contaminated materials; small Low level, long lived due to
amount of chemical wastes uranium contact or content.
Reprocessing of Spent Nuclear Spent chemicals, extracted Medium and long lived high
Fuel radioactive isotopes and other and intermediate level. Can be
elements. incorporated into Borosilicate
glass (France) or Synroc.
SNF un-reprocessed- see Uranium pellets in Zircaloy High level, long lived. Cooled in
Images 1, 2 for illustration of tubes with added outer water for up to 40years,
Scandinavian model. cladding repackaged and air cooled prior
to final geological disposal.
3. Pangea Resources
The proposal that Pangea Resources (1997 - 2000) would import other countries' SNF into Australia was strongly rejected by a majority of society, evidenced by State and Commonwealth actions. The international owners of Pangea Resources were the Governments of UK and Switzerland through their entities BNFL (http://en.wikipedia.org/wiki/BNFL) and NAGRA (http:/ /wwwns.iaea.org/downloads/rw/conventions/fourth-review-cycle/tmparis/Session%201/nagra-switzerland.pdf), both of which had lost disposal sites in their respective countries (Gosforth, Cumbria; Wellenberg, Switzerland). Perhaps the business style of Pangea was abrasive but there certainly was a strong societal opposition to the Pangea concept (NIMBY).
4
The author does not provide an opinion as to whether South Australia should import the waste of
other countries.
4. Waste Generated by a typicai1000MW NPP
Table 2: The amount of radioactive waste that would be generated by each 1000MW NPP as it is
fuelled in a 60 year life and ultimately decommissioned is approximately as follows:
Lifespan of reactor Low Level Waste Intermediate Level High Level Waste
m3pa Waste m
3pa mtpa
Year of fuelling 150m3 150m3
Online 150m3 150m3
Year 1 150m3 150m3 27mt
Year- typical 150m3 150m3 27mt
Total for 60 year operating 9000m3 9000m3 1620mt
life and defueling
These volumes (m3) for Low and Intermediate Levels are geologically small. The amount of spent
nuclear fuel discharged over a 60 year working life is relatively small in volume but due to its essential packaging and isolation space between the packages the volume of a repository is greater. These amounts have been calculated from data provided by Posiva Oy and scaled from Finland's existing nuclear program. For more exact expressions of waste quantity contact could be made with the Republic of Korea, Peoples Republic of China and repeat access to Posiva. If SA were to host more than one NPP then these quantities would need to be multiplied by the number of NPPs.
At the completion of its economic life each reactor and its containment will be decommissioned and deconstructed over a period of many years. Where possible, material will be recovered by recycling (eg concrete aggregate) . Those volumes could be comparable to other large chemical works .
WNA article Decommissioning Nuclear Facilities refers: http:ljwww.world-nuclear.org/info/NuclearFuei-Cycle/Nuclear-Wastes/Decommissioning-Nuclear-Facilities/
The final residual waste from deconstruction would require a permanent repository but is unlikely to have the same radiological intensity or life span of that of Spent Nuclear Fuel.
5. The Scandinavian method of HLW management and disposal
This Submission is based on the Scandinavian method of waste management and disposal which does not require the reprocessing of spent fuel. Should industry economics and attitudes subsequently favour reprocessing of spent fuel then the final volume of wastes and intensity of radioactivity will be greatly reduced .
5
Image 1: Showing the Scandinavian method of placement of a typical fuel bundle into a cavity in
steel inner frame which, when filled, will be fitted into the outer copper overpack. The copper end
plate is then welded to the overpack. The copper overpack will resist corrosion from any ground
water that should happen to enter the repository over time.
Used
An illustration of final placement of SNF in the Swedish and Finish system.
http://www.posiva.fi/en/final disposal/basics of the final disposai#.WlXe mgpBc
6
Image 2: A schematic showing the enriched uranium pellets fitted into a Zircaloy tube, placed into
square fuel bundles. When these used (spent) bundles are removed from the reactor and cooled
they can be fitted into a steel frame which in turn is fitted into a copper overpack. The overpack is
sealed and eventually placed into a cavity in the final repository. Clay (Bentonite) materials provide
a buffer around the canister. An array of canisters is accommodated in the repository.
fi I v
> ' '
////
Image 2: was prepared by SKB Sweden, referenced above in 1. Introduction
If reprocessing SN F is pursued then the final radioactive elements could be incorporated into
Australian invented Synroc. [Synroc is a particular kind of "Synthetic Rock", invented in 1978 by the late
Professor Ted Ringwood of the Australian National University. It has since diversified, but generally speaking is
an advanced ceramic comprising geochemically stable natural titanate minerals which have immobilised uranium
and thorium for billions of years. These can incorporate into their crystal structures nearly all of the elements
present in high-level radioactive waste (HLW) and so immobilise them. Originally some 57% of Synroc was
titanium dioxide (rutile, Ti02).)
6. Conclusion For completeness, a proponent for the siting of any step in the Nuclear Fuel Cycle in South Australia should fully describe the wastes and residuals that will be generated by the project. The proponent should also describe the management, containment and final disposal of such wastes. South Australia is well suited for the ultimate disposal of radioactive wastes due to its geological space, stability and areas of sparse population. The presence of buried minerals cont aining uranium and its daughter products that have no surface expression illustrates that in nature these deposits have remained isolated from the biosphere for millions of years. South Australia could be assessed for sites for any of the steps in the Nuclear Fuel Cycle including waste reception.
lan J Duncan DPhil (Oxon), FTSE, FIEAust 22 May 20
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Attachment A: Thesis Chapter 2: Radioactive Waste
2 .1 Introduction
This chapter defines for the purposes of this study, the nature of radioactive materials and
establishes the link between time and the decay of radioactive (unstable) elements, radiation,
radioactivity and its biological effects. A classification nomenclature is developed, recognising that
expressions of category need to be audience-specific. It discusses the period for the isolation of
each level of waste and possible disposal regimes.
The International Atomic Energy Agency (IAEA) defines radioactive waste as "any material that
contains or is contaminated by radionuclides at concentrations or radioactivity levels greater than
the exempted quantities established by the competent authorities, and for which no use is
foreseen" (NEA/OECD, 199Gb p.lG). The commonly used classification of radioactive waste is based
upon the categories of Low Level Waste (LLW), Intermediate Level Waste (ILW) and High Level
Waste (HLW). It will be shown that these categories are insufficient for an effective classification
and a more comprehensive system is required. There is also a failure by international organisations
such as the IAEA, Nuclear Energy Agency of the Organisation of Economic Co-operation and
Development (NEA/OECD), and International Commission on Radiological Protection (ICRP} and the
Commission of the European Communities (EC) to agree on a single effective classification of such
waste.
The radioactive wastes considered in this study are primarily those arising from the nuclear power
industry, scientific research and industrial and medical use. Equally the concepts and findings apply
to radioactive wastes arising from the military production of weapons and fuels . This study excludes
radioactive wastes arising from other parts of the nuclear fuel cycle, such as waste rock and mill
8
tailings from the mining of uranium ores and metallurgical processing. The considerable quantity of
depleted uranium hexafluoride {UF6), a residual from the enrichment of uranium isotopes and
considered a waste if there is no fast-breeder reactor programme, is also excluded.
Section 2.2 The Scientific Perspective of Time establishes the essential link between the creation of
radioactive matter, its decay and the scientific understanding of 'time'.
Section 2.3 Nuclear Decay, Radiation, Radioactivity and its Biological Effect discuss the relationship
between radioactive decay, radioactivity, radiation and its biological effect. Radiation is
differentiated as to type, its source and possible biological impact. The relationship between this
topic and 'time' is reinforced when considering the half-life of each species and the necessary
isolation period.
Section 2.4 Classifications of Radioactive Waste considers the standard classifications and then
adopts the more appropriate classification of Exempt, Very Low Level, Short-lived Low and
Intermediate Level, Long-lived Low and Intermediate Level and High Level Waste. This latter
classification and nomenclature is seen as a means to better inform the public of the time dimension
of any waste disposal.
Section 2.5 Concepts for Disposal of Radioactive Waste addresses the historic and proposed disposal
methods. Sea dumping, ejection into space, geological disposal, extended surface storage and
nuclear transmutation are discussed. A further parameter of disposal examined is the concept of
'concentrate and contain' versus 'dilute and disperse'. With the passage of time, will not
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'concentrate and contain' ultimately devolve to 'dilute and disperse' as in the case of geological
absorption? The link between the disposal of nuclear materials and the geographer's use of space
and time is reinforced.
Section 2.6 Conclusion finds that the appropriate classification of radioactive waste, while technically
complex and embodying space and time must be expressed in a manner that is audience-specific.
The science of decay, radiation and radioactivity is known and precise but remains a fearsome
mystery to the public. The definition of hazardous waste embodies not only its degree of hazard but
also its quantity and concentration and the declaration that it is surplus to society's requirements.
The strategy for waste disposal is to provide the space and time for all wastes to change physically
and chemically and then be absorbed into the atmosphere, hydrosphere or lithosphere such that
there is no hazard to the biosphere. The disposal mechanism must provide the time necessary for
this transformation.
2.2 The Scientific Perspective of Time
The scientific perspective of time has been influenced by astronomical, geological, archaeological
and historic observation of issues that have impacted on mankind. It is postulated that the 'Big
Bang' provided a beginning to time and became the origin of matter in the expanding universe.
Whilst Einstein's general theory of relativity underpins the concept of the Big Bang, this has
subsequently been popularised by authors such as Hawking (1994), Davies (1995a) and others. It is
estimated that the Big Bang occurred some 12-20 billion years (Ga) ago, stated more precisely by
Krane (1988, p.785) to be in the range of 14 ±2 Ga, and was the origin of energy, matter and time. It
therefore was also one source of the naturally occurring elements, both stable such as iron and lead
(56Fe, 207Pb) and unstable such as uranium, thorium and potassium (238U, ~h, 40K). Further
10
synthesis of elements took place in the stellar nucleosynthesis processes of large stars. It is
generally agreed that the Sun, a small star formed from stellar dust about 4.6-4.8 Ga ago, lacks the
mass to have been able to generate the temperatures, pressures and nuclear activity sufficient to
synthesise elements heavier than iron (56Fe). It therefore follows that all elements heavier than iron
(and probably much of the lighter material) in the makeup of the Solar System have been imported
as stellar dust arising from the Big Bang or subsequent supernovae (Krane, Ibid. p. 776, 19.5 Stellar
N ucleosynthesis).
As with the 'creation' of matter, it is accepted that time has its origin in the Big Bang and will run
continuously until the Big Crunch (Davies 1995a, pp. 220-221). The space and time of geography and
geology differs from "Einstein's 'Spacetime' which is in many ways just another field, to be set
alongside the electromagnetic and nuclear force fields" (Davies, Ibid. p. 17). In Einstein's model,
time is the one true constant about which energy and matter are interchangeable with each other.
Time is often referred to as the 'Straight Arrow of Time' which infers its constancy and irreversibility.
Price (1996) examines the debate as to the symmetry versus asymmetry of t ime and finds in favour
of asymmetry, that is, in favour of the irreversibility of time. Part of the supporting evidence for this
asymmetry is the immutable 'Second Law of Thermodynamics', a law manifest in the generation and
conversion of energy, in nuclear processes and ultimately in the decay of nuclear wastes. (2"d Law of
Thermodynamics: Heat can never pass spontaneously from a body at a lower temperature to one at
a higher temperature, after Rudolf Clausius, 1850; Walker, 1997 p. 1100). It can be argued that the
decay of radioactivity is irreversible and time dependent, which provides further evidence of the
asymmetry of time. The direct link between time and this topic is therefore self-evident.
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Uranium (234U, 235U, 238U) is the common base to the nuclear industry and is found in its natural
setting as mineralisation in rocks as old as the Archean {2500-4000 Ma). Geologically, the oldest
known commercial uranium deposits are those within the Witwatersrand Basin in South Africa .
These deposits are within rocks that have an age of about 2700 Ma. Whilst there is some debate as
to the age of placement of the mineralisation, it is generally described as being between 2400 to
2700 Ma (Barnicoat et al, 1997). The emplacement of the Cu-U-Au-Ag mineralisation in the Olympic
Dam ore body in South Australia has been dated at 1590 Ma indicating therefore that the uranium
mineralisation has been in-situ for at least that amount of time (Gairdner Johnson et al, 1995).
Other commercial uranium ore bodies in the Athabasca Basin in Saskatchewan, Canada, and Ranger
in the Northern Territory of Australia have ages in the range of 1000-1700 Ma. The youngest
sources of uranium are within the so-called 'roll front' and 'calcrete hosted' deposits that generally
have ages less than 100 Ma, and in some cases are continuing to form at the present time (personal
communication Haynes, 1999}.
The nuclear industry has an appreciation of geological space and time and finds no inconsistency in
the concept of deep geological long-term burial of radioactive wastes. The disposal of concentrated
wastes and separately, the disposal of plutonium or plutonium contaminated wastes brings with it a
moral dimension that cannot be debated here. However public concern about the security inherent
in geological disposal is further excited by the presence of man-made transuranic elements {those
with atomic numbers beyond uranium) such as plutonium e39Pu, 240Pu).
Geology provides evidence of organic and inorganic materials being trapped and contained for
extensive periods in a variety of rocks. Industry has studied analogues of waste repositories in
uranium ore bodies in Cigar Lake, Saskatchewan, Canada and Oklo, Gabon. The Oklo deposit is
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exceptional in that, as well as containing naturally occurring uranium mineralisation it contains the
decay chain elements from naturally occurring nuclear reactors (Miller et al, 1994 p. 359). In each
case the period of time that uranium and its daughter products (and in the example of Oklo, the
naturally produced fission products and transuranics) were contained in a mineral assemblage far
exceeds the time required for the isolation of all levels of radioactive waste due to its radiation.
Such wastes can however be the progenitor of a range of stable heavy metals such as lead e08Pb),
which may be chemically toxic, not unlike other heavy metals contained in mineralisation or
disposed of by society.
The natural processes of glaciation, plate tectonics, sedimentation and inundation have all been
present on or in parts of the Earth's crust during the existence of the oldest relics known to have
survived. From an industry and scientific point of view there are many analogues for the concept of
engineered and natural isolation of materials in the crust of the Earth for periods commensurate
with or exceeding the isolation periods necessary for each class of waste.
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2.3 Nuclear Decay, Radiation, Radioactivity and its Biological Effect.
The radioactive decays of naturally occurring [unstable] minerals containing uranium and thorium
are in large part responsible for the birth of the study of nuclear physics. These decays have half
lives that are of the order of the age of the Earth, suggesting that the materials are survivors of an
early period in the creation of matter by aggregation of nucleons; the shorter-lived nuclei have long
since decayed away, and we observe today the remaining long-lived decays. Were it not for the
extremely long half-lives of 235U and 238U, we would today find no uranium in nature and probably
have no nuclear reactors or nuclear weapons (Krane, 1988 p. 160).
There is evidence that the structure of the Earth and the life that it supports is dependent in part on
the heat generated by the ongoing decay of terrestrial uranium, potassium and thorium. The
tectonic and volcanic processes are in part driven by the radiogenic heat derived from the decay of
radioactive elements in the Earth (after Strachan, 1999).
2.3.1 Rate of Radioactive Decay.
The rate of radioactive decay varies for each isotope and can be as short as a fraction of a second
(e.g. 220Ra 26 ms) or as long as millions of years (e.g. 232Th 14 Ga). However for each isotope the
statistical half-life is specific and complies with the Radioactive Decay Law. If N radioactive nuclei
are present at time t and if no new nuclei are introduced into the sample, then the number dN
decaying in a time dt is proportional toN.
/...=- (dN/dt)
N
in which /... is a constant called the disintegration or decay constant.
14
Shortly after the discovery of radioactivity in 1896 it was noted that the decay rate of a pure
radioactive substance decreases with time according to an exponential law. It took several
more years to realise that the radioactivity represents a statistical change in the individual
atoms and not a change in the sample as a whole (Krane 1988, p. 161 ).
2.3.2 Radiation.
With radioactive decay there is an alteration to the original unstable atom as it decays towards a
more stable state, and the emission of radiation in one of three primary types, alpha (a), beta (13) or
gamma (y). Decay is always to a state of lower energy than the original (Wilson, 1996 p. 3). In a-
and 13-decay processes, an unstable nucleus emits an a or 13 particle as it tries to become a more
stable nucleus. In the y-decay process an excited state decays toward the ground state without
changing the nuclear species. Krane 1988, p. 174 states:
a Decay. In this process, a nucleus emits an a particle (which Rutherford and his co-workers
showed to be a nucleus of helium 4 He). An example of a a-decay process is the decay of
radium to radon, 226Ra ~222Rn +a.
p Decay. Here the nucleus can correct a proton or neutron excess by directly converting a
proton into a neutron or a neutron into a proton. This process can occur in three possible
ways, the first (negative 13 decay) emitting an ordinary electron, the second (positive 13
decay) emits a positively charged electron and the third process an electron is absorbed
thereby converting a proton to a neutron. In all three processes a particle called a neutrino
is also emitted.
y Decay. Radioactive y emission is analogous to the emission of atomic radiations such as
optical or X-ray transitions and is usually associated with extremely short half-lives. An
excited state decays to a lower excited state or possibly the ground state by the emission of
a photon of y radiation of energy equal to the difference in energy between the two nuclear
states.
The quantum of radioactivity is greatest in irradiated fuel where mutation and fission of the original
isotopes has taken place1 generating new species (actinides and fission products) that are highly
15
radioactive and unstable. Additionally, radioactive waste can be material that has become
radioactive by the impact of radiation, e.g. reactor components, or by contamination by radioactive
materials such as for protective clothing and spent fuel-reprocessing equipment. The three levels of
activity inherent in contaminated clothing, irradiated equipment or spent fuel provide examples of
the often-stated levels of LLW, ILW and HLW respectively.
2.3.3 Radiation Absorption
Radiation is absorbed by matter at different specific rates and usually converts that energy into low
level heat. One expression of this concept is that of half-distance, the distance through a material
that equates to absorbing half of the incident radiation energy. Lead, water, concrete and rock are
high absorbers of radiation to the point where 2.5m of water over a spent fuel storage facility is
sufficient to shield a work force from HLW. This concept of half-distance is important when
considering geological disposal of wastes as the half-distance for competent rock is usually less than
0.5m and therefore 200m of rock would absorb practically all radiation from the in-situ source and
provide an adequate radiological separation from the biosphere.
For example 10 m of rock would absorb 99.9999% of all radiation from a source. The percentage
amount of absorption in 10 m of rock if the half-distance is 0.5 m
= (1-0.5 1010"5)100
=99.9999%.
2.3.4 Biological Effect of Radiation
The potential biological effect of radiation depends upon the amount, type and energy level of that radiation. Materials exposed to radiation have different specific rates of absorption, which is usually expressed as the absorbed dose D. The absorbed dose indicates the amount of energy deposited by ionising radiation per unit mass of the material. The commonly used unit of absorbed dose is the
16
rod (radiation absorbed dose) equal to an energy absorption of 100 ergs per gram of material. The Sl (International System) unit for absorbed dose is the gray (Gy), equal to the absorption of 1 joule per kilogram of material, and so 1 Gy = 100 rad. A further qualification of the effect of radiation is the quality factor (QF). This is calculated for a given type (and energy level) of radiation according to
the energy deposited per unit of path length. Radiations that deposit little energy per unit length
(f3's and y's) have QF near 1, while radiations that deposit more energy per unit length (a.'s) have QF ranging up to about 20 (based on Krane 1988, pp.184-191).
Table 2.1 Quality Factors for Absorbed Radiation (Ibid. Table 6.4, p. 187) shows some representative values of QF. Table 2.2 Quantities and Units for Measuring Radiation (ibid. Table 6.5, p. 187) illustrates typical quantities and units for measuring radiation.
Table 2. 1 Quality Factors for Absorbed Radiation
Radiation QF
X rays, 13, y 1
Low-energy p, n (~ keV) 2-5
Energetic p, n (~ MeV) 5-10
a. 20
Table 2.2 Quantities and Units for Measuring Radiation
Quantity Measure of Traditional unit Sl unit
Activity (A) Decay rate curie (Ci) becquerel (Bq)
Exposure (X) Ionisation in air roentgen (R) coulomb per
kilogram (C/kg)
Absorbed dose (D) Energy absorption rad gray (Gy)
Dose equivalent (DE) Biological rem sievert (Sv)
effectiveness
The effect of a certain radiation on a biological system then depends on the absorbed dose D and on
the quantity factor QF of the radiation . The dose equivalent DE is obtained by multiplying these
quantities together:
DE= D.QF
17
The dose equivalent is measured in units of rem (roentgen equivalent man) when the dose D is in
rads. When the 51 unit of a gray is used for D, then the dose equivalent is in seivert (Sv). 1 Gy = 100
rad and so it follows that 1 Sv = 100 rem. (Based on Krane, 1988 p. 187).
The biological effect of radiation is long debated, particularly at the lower levels. There is a demonstrated level of risk with excessive doses of radiation, the original research data arising from the Hiroshima and Nagasaki atomic bomb-affected populations, early medical uses of radiation and unregulated industrial exposures. However at lower exposures there are four competitive theories as to the link between radiation exposure and biological effect. Asl shown in Figure 2.1 Dose-Risk Relationships for Radiation (after NRPB 1987, Figure 5, p. 16), the four cases are the 'Linear Hypothesis', 'Non-linear Hypothesis', 'Threshold Hypothesis' and the 'Hormesis Model' which is based upon possible benefits arising from low levels of radiation (Graham, 1996}.
Figure 2. 1, Dose-Rtsk Relationships for Radiation
t 0 a:
~
tu:: w z w m
----
/ NON-LINEAR / / /, THRESHOLD
/ ,' , / , ,
/ ,' ./ , ,
./ ,' / ,' , , , , , , --... ___ --
HORMESIS
Increase in DOSE ____..
- ---·---
Consistent with the 'linear', 'non-linear' and 'threshold' hypotheses (above the lower threshold), the
risk of a fatal cancer or hereditary effect increases with dose as quantified in the following Table 2.3.
18
Table 2.3 The Relationship Between Radiation Dose and Risk of Fatal Cancer or Hereditary Defects Annual Effective Approximate Equivalent Annual
Dose (mSv/yr) Risk of Fatal Cancer Notes
2000-6000 1 in 4/yr to 1 in 10/yr Early death likely
500 1 in 40/yr Nausea and reduction in white blood cells
likely
20 1 in 1000/yr Limit of exposure for radiation workers
2 1 in 10,000/yr Annual average dose from natural radiation
1 1 in 20,000/yr Recommended limit of exposure for
members of the public from all artificial
sources of radiation (excluding medical)
0.2 1 in 100,000/yr Maximum level of exposure for members of
the public from a nuclear installation
0.02 1 in 1,000,000/yr Lower [tolerable) level of exposure for members of the public from a nuclear installation
Based on POST (1997, p. 20 Table 3.1).
The criterion for a waste repository is that it should not have a probability of more than 1 in 1 000
000 per year (10-6/yr) of causing a fatal cancer or hereditary defect- i.e. less than one hundredth of
the average background risk level (POST 1999, p. 21). Table 2.4 Average Percentage of Source of
Radiation Dose for UK, at 2.5 mSv refers.
2.3.5 Background Radiation.
All living matter is subjected to natural radiation from the cosmos and terrestrial sources together
with radiation from artificial sources and this is referred to as background radiation. Background
radiation in the United Kingdom averages 2.6 millisieverts (mSv) pa and is as high as 7.8mSv pa in
Cornwall and as low as 2.1mSv in London. If the average exposure in the UK is 2.5 mSv pa then the
typical make-up of sources is as shown in Table 2.4.
19
Whilst the scientific expressions of radioactive decay, radioactivity and radiation are known, they are
complex to the point of being unintelligible to the public. An authoritative simplification of radiation
and its effects does not appear possible because whenever pressed for certainty, an expert must
apply further layers of complexity. The public naturally fears radiation and this has a sound scientific
as well as an emotional base. Great scientific detail and care must be exercised when protecting
workers, the public and the biosphere from radiation, but to allow discussion on the disposal of
radioactive wastes these issues need to be expressed in terms comprehensible to the public.
Table 2.4 Average Percentage of Source of Radiation Dose for UK, at 2.5 mSv Source Percentage
Natural
Cosmic 10
Gamma 14
Internal 12
Radon 47
Thoron 4
Artificial
Medica l 12
Fallout 0.4
Miscellaneous 0.4
Occupational 0.2
Discharges <0.1
Based on NRPB (1989, p. 14).
2.4 Classification of Radioactive Waste
20
The British Medical Association (BMA 1991 p. ix) defines hazardous waste as a waste that can
present a hazard to human health or the environment through either its handling or disposal.
"Whether a waste is hazardous depends on its physical, chemical and infectious characteristics and
its quantity and concentration". Radioactive waste can be hazardous due to its physical and
chemical properties as it emits radiation and can also be chemically toxic. It is present in a range of
states from being so dilute that it can be released into the biosphere without being regarded as
hazardous, to highly concentrated, requiring specific handling and isolation. Because of its
radioactivity it is regarded as a discreet waste, not covered by the general 'umbrella' of hazardous
wastes. Whilst public attention is drawn to the safeguards and procedures necessary for higher
order radioactive wastes, it is worth reflecting that low level radiation is far more diffuse in wastes,
whether declared radioactive or not, than is generally acknowledged. For example 14C and 238U in
the wastes from coal fired power stations and 209 Po in oil and gas pipelines are examples of non-
nuclear industry sources of radioactive wastes. NEA/OECD (1996b p.16) states:
Most types of waste are, strictly speaking, radioactive, because naturally radioactive materials are found throughout the environment, in the earth, in water and in the air, and inevitably appear in trace quantities in almost all wastes. However, wastes containing very low concentrations of radioactivity are generally deemed to pose no significant hazard to people or to the environment and are therefore of no concern to regulators; they are managed as if they contain no radioactivity whatever. The term "radioactive waste" is reserved for particular classes of waste, defined in national and international regulations, which contain concentrations of radioactive materials above the levels specified in these regulations.
The declaration of what constitutes waste is not always clear-cut as the material must be judged
against society's current and future needs. The debate in the UK as to the correct categorisation of
plutonium illustrates this point. For example, should plutonium up to a certain maximum quantity
be declared a potential fuel and the balance of it declared waste? Plutonium from both spent fuel
reprocessing and returned from military use could be used as a component in future mixed oxide
fuels (MOX) for light water nuclear reactors and fast breeders reactors, should that technology be
adopted. There is uncertainty as to the quantity of plutonium that should be set aside as a potential
21
future fuel in the UK but The House of Lords (1999, pp. 65-66 paras. 7.47 and 7.51) declared that any
quantity in excess of that should be declared as 'waste' . An attempt to differentiate materials as to
being waste on species or degree of hazard alone is therefore inadequate for it must also be surplus
to future requirements. It should also be borne in mind that society uses and stores large quantities
of hazardous materials other than radioactive wastes. Hydrocarbon fuels and toxic chemicals used
and stored throughout society typify these phenomena.
POST (1997 p. 3) describes the common sources of radioactive waste as arising from:
• materials and equipment which have become contaminated during the operation of nuclear power stations and the manufacture of nuclear weapons (e.g. protective clothing, cleaning materials, ion-exchange resins);
• waste arising from reprocessing nuclear fuel after it has been used in a reactor (e.g. cladding on nuclear fuel rods);
• decommissioning nuclear reactors and other nuclear facilities (including military uses);
• use of radioactive materials in university research and medicine - e.g. using isotopes to trace body processes; imaging infection and disease; radiotherapy; tracers for understanding biochemical processes; labelling DNA for genetic sequencing; and the measurement of very small quantities of biological materia ls such as hormones and proteins;
• industrial manufacture and use of isotopes for tracing corrosion in pipes; measuring fluid flows in pipes and underground reservoirs; examining stresses and strains in materials and structures; and measuring the thickness of materials;
• contaminated land at nuclear and some non-nuclear sites.
This description of source reflects the UK policy to reprocess spent fuels arising from the Magnox
and Advanced Gas Reactors (AGR) and understates the single largest source of radioactivity in waste,
being spent (used) fuel (-75% of all radiation in waste), whether reprocessed or not. The spent fuel
arising from British Energy's Pressurised Water Reactor (PWR) at Sizewell B, like many other Western
World reactors, has not currently contracted for the reprocessing of its spent fuel. Future policies
for the disposal of HLW (in the UK) must therefore encompass wastes arising from both the
reprocessing of spent fuel and spent fuel itself.
22
Generally, radioactive waste is managed according to the intensity of radioactivity and the half-life
of the dominant isotopes, the three bands being LLW, ILW and HLW. However it is desirable to
extend this classification as now discussed.
The amount of domestic radioactive waste in any country is dependent upon whether it has a
weapons industry, a nuclear power industry, and medical and scientific research. For this work it is
indicative to illustrate the amount of waste in each category applicable to the UK as shown in Table
2.5 Solid Radioactive Waste Arising in 1995 and Accumulated by 2030.
Table 2.5 UK Solid Radioactive Waste Arising m 1995 and Accumulated by 2030 (1000s m3).
Source HLW ILW LLW Total
1995 2030 1995 2030 1995 2030 1995 2030
Nuclear Power 0.06 2.55 3.7 200 7.7 800 11.5 1003
Military <0.01 <0.01 0.2 16 1.4 100 1.6 116
Industry, 0.00 0.02 0.5 23 2.5 200 3.0 223
Medicine and
Research
0.06 2.57 4.4 239 11.6 1100 16.1 1342 TOTAL
(POST, 1997 p. 7, corrected as necessary).
In the UK, disposal of existing LLW is proceeding at Drigg in Cumbria, however this site is scheduled
for closure around 2050 and there is no agreed successor site as yet. The siting for disposal of other
categories is yet to be resolved. By 2030 (assumed end of the current nuclear power programme in
23
the UK) there will be 2 570 m3 of HLW and 239 000 m3 of ILW to be disposed. These are significant
quantities of material and of contained radiation. The United States, the former USSR (FSU), China
and France would each have a similar profile although the quantities would be significantly greater
due to their respective weapons and nuclear power programmes. The greatest volume of waste is in
the category of LLW, however the greatest quantity of contained radioactivity is in HLW. The total
volume of all radioactive waste however remains small when compared to the total amount of toxic
waste produced by society.
Radioactive wastes form only a small fraction of the total amount of the toxic waste produced within
the OECD countries, which in turn is only a minute fraction of the
9 billion tonnes of solid waste that these countries produce each year. Despite these facts,
radioactive wastes have caused more public concern than any other type of waste, even though they
are neither uniquely toxic, nor uniquely long-lived. (NEA/OECD 1996, p.10).
The wastes vary considerably in their physical and chemical forms -from dilute gases and liquids,
lightly contaminated materials (LLW), large pieces of irradiated concrete and steel (ILW), to
concentrated fission products arising from spent fuel reprocessing and unprocessed spent fuel
(HLW). It varies from levels of specific radioactivity in the same order of magnitude as natural
background, to many million times background in the case of spent fuel and some medical and
industrial isotopes. From gaseous, liquid or solid wastes which are sufficiently dilute so as to be
dispersed directly into the biosphere without being regarded as hazardous, to solid wastes that must
be isolated from the biosphere for up to 100 000 years .
The parameters for the classification of radioactive waste are numerous. This analysis focuses on
the physical property of radioactivity although some wastes such as plutonium are both physically
and chemically toxic. As discussed earlier the apparent hazard of the material is not in itself a
determinant as to whether it is waste. A quantity of radioactive material can only be declared waste
24
if it is of sufficient quantity and concentration to be hazardous and surplus to society's
requirements. For example, medical diagnostic isotopes (e.g. 9E>rc, half-life 4.3 d) are hazardous
when produced but not a waste. However after the passage of several half-lives the material,
whether used or not, is then surplus to requirements and regarded as radioactive waste, although at
a lower level of hazard than when first produced.
It could be argued that all waste or its residue would ultimately be, with the passage of time,
absorbed into its environment whether it is the atmosphere, hydrosphere or lithosphere. Waste
management systems are designed to delay and modulate the possible release of such materials
until they are no longer believed to be potentially hazardous to the biosphere. This is the
application of 'time' as one of the parameters to resolve a problem generally considered only in
terms of a specified space. Domestic rubbish in a land fill repository needs to be isolated for
perhaps 100 years, LLW for 300 years, lLW 5000 years and HLW for 100 000 years after which time
chemical and physical alteration, dilution, dispersion and absorption is expected to have taken place.
Table 2.6 Comparative Processes for the Disposal of Examples of Radioactive Waste at Different
Levels illustrates this issue.
The standard classification for radioactive waste falls within the categories of Low Level Waste
(LLW), Intermediate Level Waste (ILW) and High Level Waste (HLW). More recently, in the interests
of a more effective division, a lower category of Very Low Level Waste (VLLW) and a subdivision of
LLW and lLW into that having a shorter life (non alpha) from the long lived (usually containing some
uranium or plutonium) have been promoted. These sub-categories are important to public
understanding and to the efficient disposal of such wastes. The class of VLLW radiologically abuts
that which regulators allow to be disposed of (with or without dilution) directly into the biosphere,
common with Exempt Waste (EW).
25
Table 2.6: Comparative Processes for the Disposal of Examples of Radioactive Waste at Different Levels
Material-state Example Containment Process Dispersion to
Gas Radon 'uRn, Not contained Diluted, released Atmosphere
3.82d continuously
Krypton 8~Kr, Can be retained in Released in Atmosphere
10.7y plant for a short batches, diluted
period
Liquid Medical, research Retained for Diluted into Hydrosphere
laboratory, periods necessary sewer or
nuclear plant to meet standards dispersed into
effluents bodies of water
Solid Ash from Dilute with non- Dispersed into landfill, isolation
incineration of radioactive waste landfill for 100 years
LLW
Contaminated Compacted, Specific landfill Shallow
clothing (LLW) contained lithosphere
isolation for 300 y
Irradiated Compacted, Direct placement Deep lithosphere
machinery (ILW) contained into rock at 200m isolation for 5000
years
Irradiated spent Conditioned, Proposed direct Deep lithosphere
fuel or cooled, contained placement into isolation for
reprocessing rock at 500m
residues (HLW) 100 000 years
For the past thirty years there has been technical debate as to the most appropriate framework and
levels of classification for radioactive waste with technicians and public relations entities at odds
over the best form of presentation. The issue of a single international standard is complicated by
national and institutional differences illustrated by the ongoing debate within the IAEA and also
further debate between the IAEA, NEA/OECD, ICRP and NRPB. The ongoing evolution of the
understanding of wastes and their possible impact on health and the environment needs to be
explained but it has become clear that data needs to be differentiated for specific audiences, and
this further complicates the issue. From the original classification of LLW, ILW and HLW, there is
now a trend towards a further differentiation at the low end to accommodate Exempt Waste (EW)
and Very Low level Waste (VLLW). There is also the temporal sub-division in the low and
intermediate classes to show short-lived (LILW-SL) and long-lived (LILW-LL) wastes. These are
beneficial clarifications that will not only aid public understanding but also remind the audience of
the temporal dimension of the issue.
In the industry interface with the public, it is essential to use a descriptive process that is firstly
honest and accurate but at the same time explicit and readily understandable by a majority of the
public. Such a classification is that taken direct ly from POST (1997, p.4).
• Very Low Level Waste (VLLW) is such a low level that it can essentially be treated as normal non-radioactive waste - i.e. can be sent to landfill sites licensed for domestic and other wastes without special treatment.
• Low Level Waste (LLW) generally includes items such as paper towels, gloves, protective clothing and laboratory equipment that has been used in areas where radioactive materials have been handled. LLW requires no shielding (from its radiation) and is current ly compacted into drums placed in containers, which are infilled with cementitious grout and buried at shallow engineered sites.
• Intermediate Level Waste (ILW) is often material and equipment that has come into contact with, or been near to the active materials in a nuclear reactor, and its higher levels of radioactivity, generally require shielding and special handling. ILW arises during the operation of a reactor, during the reprocessing of nuclear fuel and when decommissioning nuclear installations.
• High Level Waste (HLW) is so highly radioactive that the decay processes generate significant excess heat. This waste is produced when spent fuel is reprocessed. Where spent fuel is to be
disposed of without reprocessing; it too is classified as HLW. Although HLW accounts for only -1% of the total volume of radioactive waste, it contains nearly 75% of all radiation in waste.
The EC and NRPB (1997) established a classification that is more scientific and takes into account
Exempt Waste (EW) and the division between short-lived and long-lived LLW and ILW. An extract
from this publication states:
a) Exempt waste (EW)
This is waste with such low concentrations of radioactivity that its radiological impact is
considered to be trivial and it does not need to be reported .
b) Short-lived low and intermediate level waste (LILW-SL) Most of the identified legislation and recommendations concentrate on the boundary
between low level short lived waste and that which is more active and longer lived. This
position has arisen because of the two clearly defined waste disposal routes . It is accepted
that the former may be disposed of by engineered shallow land disposal. Any waste more
active than this must be disposed of in a deep geological formation. The most common
criteria used are an alpha emitter limit of 370 Bq/g (average over the entire repository) and
3,700 Bq/g maximum per package. Typically a similar concentration is applied to long lived
beta/gamma radionuclides, with the limit being about 10 times larger (104-105 Bq/g) for
short lived beta/gamma emitters. The most common method of distinguishing between the
two is by a half-life limit of 30 years.
c) Long-lived low and intermediate level waste (LJLW-LL)
This waste containing a greater concentration of ]ong Jived radionuclides than the definition of LIL W -SL, and hence requires deep disposal. However the radionuclide content is such that the heat output need not be taken into account.
d) High level waste (HLW)
It is generally accepted that the boundary between LIT.., W-LL and HL W should be by heat generation or source definition (i.e. origin and nature of the waste itself). This waste will require storage (to allow cooling) before disposal in a deep repository. Historically, ill W is defined by source definition, often as waste from the first extraction cycle of reprocessing, and irradiated fuel elements if they are declared waste, or waste of equivalent radiological burden. The definition of heat generating waste is a radio-thermal output of at least 2 kW.m-3 (suggested by IAEA).
28
Table 2. 7 Comparative Activity of Radioactive Wastes (Bqlkg)*
Waste category Beta and gamma activity Alpha activity
VLLW <400 <400
LLW 400-12 million 400-4 million
ILW >12 million >4 million
HLW No figures given No figures given: waste so
active as to generate significant
heat
*The activity of wastes is the number of radioactive disintegrations per second (becquerel, Bq) in a
kilogram (kg) of material. (Taken from POST 1997, p. 4).
A suggested Revised Classification of Wastes and the current status of disposal at the end of the 201h
century, expressed for public consumption but stil l technically competent, is as follows :
Type 1 Radioactive Waste
EW and VLLW (gas, liquid and solids such as radon, laboratory effluents and contaminated tissues)
are released into the biosphere (atmosphere, hydrosphere or lithosphere) where it is further diluted,
dispersed and generally regarded by regulators as being non-hazardous. This practice takes place in
all developed countries.
Type 2 Radioactive Waste
LLW (solids such as protective clothing, laboratory equipment) is compacted, contained and placed
into designated shallow earth burial that should remain competent for up to 300 years after which it
29
is assumed to be non-threatening to the biosphere. This practice takes place in some (e.g. UK, USA,
Sweden, Finland, Japan and Spain) but not all countries.
Type 3 Radioactive Waste
ULW-Sl waste (solids such as used equipment, filters, heavily contaminated materials) is compacted,
contained and placed at depths of 200-250metres in competent rock. Such repositories need to
remain competent for up to 5000 years, after which it is assumed any residue can be absorbed into
rock and other engineered barriers without threatening the biosphere. Such sites are operating in
Sweden (Forsmark), Finland (Oikiluoto), and Spain (EI Cabril).
Type 4 Radioactive Waste
LILW-ll wastes (solids such as plutonium-contaminated materials, heavily irradiated equipment, fuel
cladding) are compacted, contained and placed at depths of 250m or more. Due to its long life it can
be treated similarly to HLW although it is not heat generating. An example of this is the plutonium
contaminated waste from the US military programme which is now being placed into a Permian salt
bed at a depth of 600m at the Waste Isolation Pilot Plant (WIPP), Carlsbad, NM (visited May 1999).
Type 5 Radioactive Waste
HLW in solid form arises from spent fuel, reprocessing of spent fuel, medical, industrial and military
materials. These are cooled, contained and most probably will finally be placed in rock repositories
with depth of at least SOOm. At present no such repository is developed or is in use and HLW is
30
placed in surface wet or dry interim storage in each nuclear country. HLW, if in liquid form (usually a
residue of military processing and particularly in the US and FSU), is being progressively solidified
and will finally be treated with other solid HLW. Tentative sites for HLW disposal have been
nominated in the US (Yucca Mountain), Finland (Oikiluoto), Germany (Gorleben) and France (Meuse
Haute Marne). Additionally there are active (non-candidate) underground research laboratories in
Sweden, Switzerland, Canada and Japan.
2.5 Concepts for Disposal of Radioactive Waste
Consistent with many of the developments since the Industrial Revolution, the disposal of
radioactive waste became secondary to the prime cause of such waste. The 'benefits' of medical
and military use, scientific research and more latterly, nuclear power were always regarded as being
greater than any disability that might arise from the disposal of the wastes arising. There was the
belief that an appropriate disposal regime would evolve in time to take care of the expected wastes
and scientists and engineers set about developing and demonstrating the necessary processes. In
retrospect there was the lack of life cycle concerns in modern industrial and military activity,
exemplified by the manufacture, use and disposal of chemical weapons (e.g. mustard gas, napalm),
under the military axiom that national defence is supreme and all other issues are secondary. This
juxtaposition remains true for medical and dental X-rays, where the long-term effect is not known
precisely but it is assumed, by professionals and the public, that the benefits will out-weigh the risks.
Society took the immediate benefits of energy and sophisticated materials with a delayed concern
for the life cycle environmental impact until some scientists and the embryonic green movements
sounded the alarm in the late 1970s. Until that time there was insufficient awareness as to the
potential danger that could arise from the handling and disposal of radioactive materials. For
example the laboratory of Marie Curie in Paris was found to be so heavily contaminated with radium
31
that it was dangerous and far exceeded today's health regulations (Lewiner, J., L'Ecole Superieure de
Physique et de Chemie, Paris; visit May 1997). Until the 1980's the use of uranium and plutonium by
the military was protected from public view and as has now been revealed, was handled with a
disregard for the environment as discussed in Chapter 6.
A perspective of waste disposal in the late 1970's is captured in the Royal Commission on
Environmental Pollution, Sixth Report (1976), usually referred to as the 'Flower's Report', after its
chairman. It was recognised for the first time that, whilst the use of nuclear power was accelerating
in the Western World and FSU, there was still no proven waste disposal regime. This, at a time when
public understanding of the magnitude and nature of the problem was occluded by secrecy within
the military and civil users of nuclear power, precipitated the formation in the UK in 1982 of the
Nuclear Industry Radioactive Waste Management Executive (United Kingdom Nirex Limited or
Nirex). It also engendered an urgency, which in retrospect may have been a contributing factor to its
lack of success (interview Roberts, L., 6 August 1997).
The concepts for disposal of solid wastes at the time of the Flower's Report included:
• Emplacement in geological formations on land. Possible host materials studied included
evaporites, sedimentary rocks including clays and hard rock. The depth of placement is
determined by site specific parameters but reflects the required integrity for the necessary
isolation period. This remains the most likely disposal method as generally stated in The House
of Lords Third Report {1999).
• Indefinite storage on or near the surface. This method inferred continuing human supervision,
periodic repackaging if necessary and the underlying hope that a better disposal method would
evolve. Greenpeace and other environmental organisations favour this option although in the
32
case of Greenpeace it is tied to their policy for the closure of the nuclear power option.
(Interview Parr, 0., Green peace, 28 July 1999).
• Placing wastes on the bed of the deep ocean. Historically LLW and ILW wastes were 'dumped'
into water of several kilometres depth. Studies suggested that HLW could, in longer lived
canisters, also be 'dumped' or placed into a structure on the seabed. The UK excluded sea
dumping in 1983 after the Treaty of london, it being one of the last western countries to give up
this practice.
• Emplacement in the sediments of the deep ocean. The main method envisaged was the use of
'penetrators': torpedo-shaped outer canisters, which would embed themselves into the ocean
floor. Society no longer considers this as a viable option although there remains a technical
interest.
• Emplacement in the rock beneath the deep ocean. This option consists of placing canisters of
waste in boreholes drilled in the ocean floor. In an engineering sense it is possible using offshore
oil and gas technology, but technically difficult. It is no longer considered a viable option
however, largely due to the rejection of all things in the image of sea dumping.
• Subduction zones. Subduction zones in a deep ocean abyss were considered on the basis that
waste placed in the zone would be entrapped in the subducting plate and be drawn into the
mantle. An extensive study undertaken by the NEA/OECO resolved that this option should not
be pursued for reasons of technical uncertainty, and political and societal attitudes. There is
however an argument in favour of deep-ocean placement of some solid wastes as being the
33
least environmentally damaging but public opinion and therefore political emphasis is currently
against such a concept.
• Placing wastes in Antarctic ice sheets. HLW, which is heat generating, would be placed on the
ice shield and penetrate down, with the water re-freezing above. This is no longer considered
for technical, environmental and political reasons.
• Ejection into space. As late as 1980, the US DOE advertised the option of sending wastes into
space where it would orbit the Sun and eventually be drawn into it. This concept was
abandoned for many reasons, not least being the random failure of rockets at launch and
particularly after the loss of the Challenger Shuttle Vehicle (16 January 1986).
In addition to the existing disposal mechanisms there are at least two processes under development
that are designed to reduce future hazards from HLW. Traditionally HLW derived from reprocessing
spent fuel is solidified and incorporated into a solid boro-silicate glass matrix, which in turn is cast
into a steel vessel. The following developments are aimed at reducing the radioactive half-life of the
wastes and providing an alternative matrix for encapsulation.
• Partitioning and Nuclear Transmutation. The proposal is based upon the separation of long-lived
radionuclides from wastes and then the transmutation of these species into short-lived species
or stable elements. Such transmutation would be done in a reactor or a particle accelerator
(Venneri, 1999}. There is concern that in turn it will produce an additional radiation burden.
The concept is technically difficult and currently uneconomic and unproven. The concept
though, does address the issue of reducing the time dimension for isolation, such that it might
be more acceptable to the public (Duncan 1999, p. 12, Figure 3).
34
• SYNROC. A synthetic rock-like substance capable of absorbing crystalline waste materials into its
molecular structure, thereby enhancing the resistance of the waste to dissolution in water. This
proposal is an alternative to the use of boro-silicate glass as a waste absorbing matrix and is only
part of a disposal package. Both matrices then require containment and an acceptable disposal
method such as geological placement.
Research into underground repositories has been conducted in many countries and has addressed
all known physical and chemical issues such as hydro-geology, heat generation and transfer, gas
generation and migration, rates of corrosion, mobility of species in the rock, rock competence and
mining method. Some research has been generic, other site specific. As an indication of the extent
of such underground research, past and current facilities are listed in Table 2.8 Radioactive Waste
Disposal Underground Research Facilities. The current concepts for disposal of all regulated (e.g. not
EW or VLLW) radioactive wastes are based upon solidification, compaction, containment and finally
a form of geological placement with interim storage provided for heat generating HLW. The lack of
approved final disposal sites for ULW-SL and ULW-LL in most countries and for HLW in all countries
has in turn perpetuated and extended the period for interim surface storage further than was
originally planned.
Shallow earth burial of LLW in engineered sites has been accepted in most nuclear countries. The
compaction, encasement and final placement of LILW-SL is taking place in some countries (e.g.
Sweden, Finland, Spain and US) but notably not in the UK. The final disposal of LILW-LL and HLW is
planned in some countries (e.g. Germany, US and Finland) but yet to be planned or developed in
other nuclear countries. No country is currently permanently disposing of such wastes but deep
geological disposal is the most often stated likely form for such repositories. The alternative
concepts for disposal listed in this chapter have, for the time being, been abandoned.
35
Archaeology provides much evidence of anthropic activity such as cave painting (Upper Palaeolithic,
30 000-10 000 BC), bronzes from the Greek Bronze Age (c3000 BC) and the pyramids, (c2200 BC),
which have survived without specific engineering or maintenance. These illustrate the periods of
time commensurate with the period required for the isolation of LILW-Sl. Many maintained
buildings in Europe have remained functional for periods exceeding the period required for the
isolation of LLW (e.g. Westminster Abbey, London, cl31h Century; Christ Church Cathedral, Oxford,
cl61h Century). Such examples do not, however, indicate the number of similar structures that have
failed to survive.
Opinion formers in industry and most governments, having abandoned 'ocean dumping' of solid and
liquid wastes, became convinced of the appropriateness of geological disposal of wastes. This
concept is often referenced as the most likely form of repository in The House of Lords Third Report
(1999) and elsewhere. Industry appreciation of the need for public acceptance of such disposal was
illustrated by its attempts to inform the public in terms of geology and archaeology, as each provides
examples of stable environments that have survived longer than the period required for the isolation
of waste.
2.6 Conclusion
This chapter has discussed the underlying science of time, nuclear decay, radioactivity, radiation and
its biological effect. The scientific link between time and the topic is established. Radioactive waste,
its classification and possible disposal method is discussed. National and international debates
continue between agencies such as the ICRP, NEA/OECD, NRPB and IAEA as to the appropriate
classification and boundary levels between classes. The dislocation between the scientific
36
description of waste and a description that is understandable to the public, without loss of veracity,
has been explored and leads to the statement of a Revised Classification of Wastes (p. 43).
Table 2.8 Radioactive Waste Disposal Underground Research Facilities Location Facility Geology and depth Dates
Country
Belgium Moi/Dessel HADES u/g research Clay, 230 m Started 1983
lab.
Canada Lac du Bonnet, Underground Granite, 240-420 m Excavation
Manitoba research lab started 1984
Germany Konrad Research in former Jurassic strata Investigations
iron ore mine overlaid w ith clay, started in 1976
800-1300 m
A sse Former salt mine Salt dome Operational
<1000 m repository
1967-78
Gorleben* Research in salt Salt dome overlaid Shafts now
formation by gypsum rock <900 sunk
m
Morsleben Research in former Salt dome <525 m Safety related
sa lt mine investigations
in 1960's
Japan Horonobe Deep underground Sedimentary rock Planning
research facility <1000 m
Sweden Aspo* Hard rock lab Granite <460 m Active research
Stripa NEA u/g research in Granite <400 m 1980-1992
former iron mine
37
Switzerland Grimsel* Underground rock Crystalline bedrock Started 1984
laboratory inside a mountain
<450m
UK Sellafield* Rock Classification Tuff, Sandstone <920 Rejected
Facility m
United States Yucca Mountain* Active research and Tuff"'300 m Awaiting
development approvals
Carlsbad, NM* Waste Isolation Pilot Permian salt bed Operating
Plant (WIPP) "'600m
Based on data from NEA/OECD 199Gb. *Sites visited by author.
In essence, the disposal of radioactive waste in the UK remains unresolved, save for the disposal of
EW and VLLW into the biosphere and LLW in engineered land fill (Drigg). Progress has been made in
some other countries for the disposal of LILW-SL and LILW-LL as referenced however the final
disposal of HLW (whether arising directly from spent fuel or the reprocessing of spent fuel) remains
unresolved in all countries. Whilst some countries have nominated research sites for the disposal of
LILW-LL and HLW (e.g. USA, Finland and Germany) there are not as yet any approved disposal sites
for these materials. It is generally expressed that the solidification, compaction and encasement of
all radioactive wastes leading to placement at appropriate depths in the lithosphere is the preferred
final disposal model. The ever-increasing quantity of radioactive waste and ongoing public concern
are valid issues which are yet to be resolved.
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There Is the realisation that any final disposal method must allow for the concept that ultimately all
of society's waste is diluted and dispersed into its near field. The disposal mechanism must provide
the time necessary to allow for that which is 'concentrated and contained' to be altered and
dispersed into its environment without hazard to the biosphere - the result of a truly dynamic
process bounded by space and t ime.
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