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