JRC Ispra Summer School, 9-13 September 2013

Final waste packaging

for disposal

Lecture content

• Waste from decommissioning

• Waste management approaches

• Radioactive waste classification and disposal solutions

• Waste management approaches

• Treatment and conditioning

• Waste form, containers and Final Waste Package

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Radioactive waste producers

Many socially beneficial activities use radioactive materials, producing

radioactive waste as an unavoidable by product:

• Nuclear energy production (both in the operations and in the

decommissioning phase)

• Medicine (diagnosis and treatment of diseases, medical research, testing of

new pharmaceuticals)

• Industrial activities (non destructive testing, smoke detectors, food

preservation)

• Research activities (research reactors, accelerators, testing of materials)

• Defense nuclear programme

• Processing of raw materials containing naturally occurring radionuclides

(NORM)

Waste from nuclear power plants, especially decommissioning activities,

accounts for half of the overall volume and most of the overall radioactivity

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Nuclear site remediation plan

Remediating a nuclear site may require the following activities:

• Removal and safe storage of nuclear fuel (in case of power plants)

• Safe conservation of the infrastructures and systems during the remediation

• Decommissioning (characterization, dismantlement, decontamination)

• Waste management (operation waste and waste from decommissioning)

• Final clearance and release of the site

The decommissioning of a nuclear facility at the end of its useful lifetime is

considered as the first phase of radioactive waste management

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Waste from decommissioning

Decommissioning activities generate large quantities of materials most of

which are either directly released or cleared after decontamination.

Only a small percentage of such materials cannot be reused or recycled and

must be treated as radioactive waste

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58%

40%

2%

Conventional Free release Waste

Waste management approaches

• CONCENTRATE AND RETAIN

Reduction of volume and confinement of

the radionuclide contents by means of a

conditioning process to prevent dispersion

in the environment

• DELAY AND DECAY

Holding the waste in storage until the

desired reduction in activity has occurred

through radioactive decay of the

radionuclides contained in the waste

• DILUTE AND DISPERSE

Discharging waste to the environment in

such a way that environmental conditions

and processes lead to concentrations of

the radionuclides which cause acceptable

radiological impact

Typical of radioactive

waste, require storing and

isolating waste for up to

long times

Widely used in today's

non-radioactive waste

management

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Radioactive waste classification and disposal solutions

IAEA classifies radioactive waste according to the disposal solutions suitable

to safely store the different waste categories

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Aims of disposal

1.10 The specific aims of disposal are:

(a) To contain the waste;

(b) To isolate the waste from the accessible biosphere and to reduce substantially

the likelihood of, and all possible consequences of, inadvertent human intrusion

into the waste;

(c) To inhibit, reduce and delay the migration of radionuclides at any time from the

waste to the accessible biosphere;

(d) To ensure that the amounts of radionuclides reaching the accessible biosphere

due to any migration from the disposal facility are such that possible radiological

consequences are acceptably low at all times.

1.16. … the ability of the chosen disposal system to provide containment of the

waste and to isolate it from people and the environment will be commensurate with

the hazard potential of the waste

Basic principles– IAEA SSR-5

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Safety approach for ‘near surface’ disposal

0

200

400

600

800

1000

1200

0 30 60 90 120 150 180 210 240 270 300

BIOSPHERE

BARRIERS (design life 300 y)

WASTE YEARS

RADIOACTIVITY OF ‘SHORT-LIVED’ RADIONUCLIDES

• Limiting the overall inventory to be disposed of to ‘short lived’ waste (i.e. Half-

life max 30 y) with small quantities of ‘long lived’ radionuclides (i.e.< 370 Bq/g)

• 300 y = 10 half-lives 1/210 ≈ 1/1000 of the initial ‘short-lived’ waste activity

• Institutional control period of ≈ 300 y reduces the intrusion probability

• Multiple barriers in series contain waste and protect from unintentional

intrusion (passive protection)

• Monitoring and treating possible water infiltrations/releases (active protection)

Delayed migration of

‘Long-lived’ nuclides

LLW disposal safety in the long term

• After about 300 y the ‘short-lived’ radionuclides are almost completely decayed; the

artificial barriers can no longer assure the containment of the residual radioactivity

connected to the ‘long-lived’ radionuclides.

• The site geology supplies the required containment by preventing and/or delaying the

return of radioactivity to the biosphere.

• Performance Assessment is a proven methodology to model the transport of the

remaining radionuclides to the environmental matrices (soil, water, air) and calculate the

corresponding doses to the critical group in all possible scenarios

REPOSITORY

DOSE

AIR SURFACE

WATER GROUNDWATER

BIOSPHERE

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Performance Assessment output (typical)

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Multiple barrier approach for surface LLW repositories

Waste Package

(1st barrier)

Module

(2st barrier)

Cell

(3rd barrier)

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LLW repository

Radioactive Waste Management approaches

Industrial and sanitary

waste producers

WASTE CLEARABLE GAS AND LIQUID

Dilute & Disperse

Interim Storage

Concentrate & Retain Delay & Decay

Disposal

• Surface

ENVIRONMENT

Early releases

Delayed releases

Coventional

recycle/disposal

VS

LW

Delay & Decay

VLLW-LLW

Disposal

• Underground ILW-HLW

• Minimize at source

• Segregate

SOLID MATERIALS

Clearance & recycling

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Processing the waste (both liquid and solid):

• Pretretament/treatment

Liquid waste: evaporation/drying, filtration, wet oxidation

Solid waste: compaction/supercompaction, combustion, thermal

decomposition (e.g. plasma), …

• Conditioning

Liquid waste: immobilisation of the radioactivity in a matrix (cement, bitumen

polymer, glass) at a microscopic level

Solid waste: contaminated or activated parts and objects embedded within

cement matrix.

How to concentrate & retain ?

In this way the waste is converted into a solid waste form, enclosed in containers. The waste form

is the first ‘barrier’ of a series of barriers of a disposal repository designed to ensure that the

radioactivity is retained (confined) for the required time period

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Waste treatment - Supercompaction

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Supercompaction is a low cost, well proven treatment process, leading to

volume reduction up to 5:1

Waste form + container = Waste Package

suitable for handling, transport, storage and/or disposal.

Waste form

Container

Waste package

Waste Package

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Functions of the waste form

• During transport and handling the waste form ensures that radioactivity is

not present in a gaseous, volatile, liquid or fine particulate form to such an

extent that the waste package fails to meet the safety goals.

• After emplacement in a repository the waste form, together with the

container, provides the first physical barrier to the release of radioactivity

from the waste package. The waste form ensures long term physical,

chemical and thermal stability immobilizing the radioactive materials (slow

releases when contacted with water) and resist leaching, powdering,

cracking and other degradation

• The waste form should be compatible with the container material to ensure

that the properties of the waste package as a whole are maintained.

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Conditioning by cement encapsulation

Encapsulation with cement is the most

employed way of conditioning both liquid

and solid radioactive waste.

Advantages:

• Proven technology

• Simple and low cost process

• Good chemical and biochemical stability

of the waste form

• Resistance to fire, good stability and

durability of the waste form

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Case history: Garigliano in drum liquid cementation

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How to choose the Waste Containers

RADIOACTIVE

INVENTORY

CONSTRAINTS

SITE

CONSTRAINTS

ALLOWABLE

DOSE RATE

PHYSICAL

CONSTRAINTS

HANDLING

CONSTRAINTS

•Available space

•Available handling

equipment

•Dimensions and

weight of generated

waste

•Stackability

•Lifting

•Need for remote

handling

•Accepted forms

and materials

•External volume

•Payload

•Max gross weight

•Radiological WAC

for storage/disposal

•Allowable dose rate

for handling

• IAEA transport

classification

•Radiological

WAC for

storage/disposal

WASTE FORM

CONSTRAINTS

• Internal Corrosion

•Gas Generation

•Allowable dose rate

for transport

STORAGE

CONDITIONS

•External

corrosion

•Protective

cotaing damage

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Waste Acceptance Criteria (WAC) are a set of conditions to be fulfilled by

waste packages in order to be accepted for storage or disposal into a

repository.

WAC are usually specified by the repository operator and/or the Control

Authority on the basis of the repository system characteristics and the

Performance Assessment.

Typical WAC:

• Radiological: radioactivity concentration in the final waste package below

predefined limits (Bq/g and/or Bq/cm2)

• Physical: shape, dimensions and gross mass of final waste package and

material of waste container within standard limits

• Waste form characteristics according to predefined standards

• Exclusion of specific hazardous materials

• Exclusion of free liquids above predefined %

• Exclusion of flammable materials

Waste Acceptance Criteria

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Drums

• CC-440-A

• CC-440-B overpack

• CC-440-C with lost paddle

LLW-ILW cylindrical container (Sogin)

External dimensions(ø, h)

m

0,791 1,1

Homogeneous

waste form Non homogeneous

waste form

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Type

External

volume

m3

External dimensions

(h, l, p)

M

CP-2.6 2,6 1,25 1,65 1,25

CP-5.2 5,2 1,25 2,50 1,65

CM-10.8 10,8 1,70 3,05 2,09

LLW-ILW prismatic container

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Is it possible to condition waste without matrix while keeping the same overall

performance of the Final Waste Package?

Robust waste containers

Conditioning with

matrix: Waste package

performances assured

by the system

container+wasteform

Conditioning without

matrix: Waste package

performances assured

by special container By strengthening the container features it is

possible to reduce the waste form contribution to

the overall resistance

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HLW special container (concept)

Special container assuring confinement of waste w/o need of matrix.

Suitable for temporary storage, transport and potentially for final disposal

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Waste Package shall fulfill requirements derived from all phases of the

whole life cycle, from production to disposal:

• Treatment and Conditioning

• Handling on generator/conditioner site;

• Interim Storage on site;

• Transport to centralized Long Term Storage (depending on national

strategy);

• Long Term Storage (depending on national strategy);

• Transport to disposal Facility;

• Disposal and related Long Term Performance Assessment of

repository (WAC)

Waste Package requirements

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Waste Package safety functions

• Ensuring that any operation associated with handling, interim storage,

transport and emplacement of the waste packages to the disposal facility, is

carried out safely.

• During the normal operations preceding repository closure, radiation dose to

workers and members of the public is minimised through the containment

and shielding provided by waste packages and other components of the

transport system and of the storage/disposal facility.

• To respect the dose rate limits in trasport (i.e. 2 mSv/h in contact, 0,1 mSv/h

at 1 m) it may be necessary to shield the container.

• Shielding can be either built-in the container or obtained using a reusable

shielded transport overpack to host the waste packages.

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Conclusions

• The safe disposal of radioactive wastes requires their isolation from the

environment for the time necessary to let them decay to non hazardous

radioactivity levels

• Such approaches are known as ‘concentrate and retain’ and ‘delay and

decay’

• Waste management includes treatment and conditioning of the waste in

order to reach a waste form solid and stable, enclosed in a durable container

• Waste package is the combination of container and waste form

• A waste package must fulfill requirements derived from all phases of the

whole life cycle, from production to disposal

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Thank you