International Atomic Energy Agency RAS/9/071 Regional Training Course on Modular Design of Processing and Storage Facilities for Small Volumes of Low and Intermediate Level Radioactive Wastes including Disused Sealed Sources, Indonesia, 30 Sep – 4 Oct, 2013 Overview of Predisposal Management of Radioactive Waste S.K.Samanta Waste Technology Section (WTS) Division of Nuclear Fuel Cycle and Waste Technology
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International Atomic Energy Agency
RAS/9/071 Regional Training Course on Modular Desig n of Processing and Storage Facilities for Small Volumes of Low and Intermediat e Level Radioactive Wastes
including Disused Sealed Sources, Indonesia, 30 Sep – 4 Oct, 2013
Overview of Predisposal Management of Radioactive
Waste
S.K.SamantaWaste Technology Section (WTS)
Division of Nuclear Fuel Cycle and Waste Technology
International Atomic Energy Agency
What is radioactive waste?
• Waste is material for which no further use is foreseen
• The waste can be in gaseous, liquid or solid form.• Radioactive waste is a waste that contains, or is
contaminated, with radionuclides at concentrations equal to or greater than clearance levels established by the regulatory body (definition for legal and regulatory purposes)
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Nuclear Fuel Cycle and Waste
Natural Uranium & Thorium
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Non-Nuclear Fuel Cycle Waste
• Application of radioactive material in medicine, industry, agriculture and research
• Research reactors• Non-nuclear industry (mining of ores, oil industry, phosphate
industry, etc.)
Lightning conductorRadioisotope thermoelectric
generator - RTG Teletherapy machine
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Categorization of operational waste
• Point of origin− Nuclear fuel cycle, Nuclear
power plants, Research reactors, Nuclear applications, etc
media, sludge− Combustible solids and liquids− Compactable solids− Metal
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Classification of radioactive waste - IAEA
• Exempt waste (EW)• Very short lived waste (VSLW)• Very low level waste (VLLW)• Low level waste (LLW)• Intermediate level waste (ILW)• High level waste (HLW)
This classification defines the most appropriate disposal routes (end-points) for solid or solidified waste.
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Example of application of IAEA classification schem e
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Terminology
IAEA Safety GlossaryTerminology Used in Nuclear Safety and Radiation Protection — 2007 Edition
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What is Predisposal?
• Any waste management steps carried out prior to disposal, such as pre-treatment, treatment, conditioning, storage and transport activities.• Predisposal is used
as a contraction of ‘pre-disposal radioactive waste management’, not a form of disposal
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Pre-Treatment of radioactive waste
• Pre-treatment includes any operations prior to waste treatment, to allow selection of technologies that will be further used in processing of waste (treatment and conditioning), such as:• Collection;• Segregation;• Chemical adjustment; and• Decontamination
Sorting waste at Bohunice Treatment and Conditioning Centre for radwaste, Slovakia
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Treatment of radioactive waste
• Operations intended to benefit safety and/or economy by changing the characteristics of the waste
• Three basic objectives:−Volume reduction−Removal of radio-nuclides−Change of composition
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General scheme for treatment of liquid waste
Treatment
Waste concentrate
Conditioning
Storage/Disposal
Discharge to environment
Liquid waste
Treated effluent
DF = A1/A2
VRF = V1/V2
V1, A1
V2
A2
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Selection of treatment process for liquid waste
• Waste characteristics (volume, generation rate, activity, chemical composition, etc)
• Discharge requirements for decontaminated effluents
• Particulates and aerosols in gases may be removed using HEPA filters;
• Iodine and noble gases can be removed by filters or sorption beds with activated charcoal;
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Treatment of gaseous waste (2)
• Redundant filters may be required for safety reasons;
• Pre-filters or roughing filters, temperature and humidity controls, and monitoring equipment;
• Used filters and sorption beds are managed as solid waste ;
• Concentrations of radionuclides should not be allowed to exceed levels accepted for future conditioning, storage or disposal.
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Treatment methods for solid radioactive waste
• Mechanical treatment − Low force compaction− High force compaction (supercompaction)
• Thermal treatment− Incineration− Pyrolysis− Molten salt oxidation
• Melting− Metal melting
• Chemical methods− Acid digestion− Chemical/photochemical oxidation
• Biochemical decomposition
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In-drum Compaction
• Compressive force− 10-50 tonne
• Volume reduction factor− 2-5
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Super-Compaction
• Compressive force− 1200-1500 tonne
• Volume reduction factor− 10-15
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Incineration
• High volume reduction factor− 50-100
• Temperature− 900-950 °C
• Off-gas purification− Scrubber− Filter
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Conditioning of radioactive waste
• Those operations that produce a waste package suitable for handling, transport, storage and/or disposal
• May include:− Immobilization, i.e., conversion of waste
into waste form by solidification, embedding or encapsulation
−Enclosure of the waste in containers−Providing an over-pack (if necessary)
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Waste streams for conditioning
Examples:
− Precipitated sludge from chemical treatment − Spent ion exchange resins from ion exchange
treatment − Retentate from Reverse Osmosis − Retentate from Cross-flow Filtration− Evaporator concentrates− Organic liquids
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Matrix materials for waste conditioning
• Cement• Bitumen• Polymer• Glass• Ceramics
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Cementation of aqueous waste
In-drum mixing In-line mixing
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Organic liquid waste solidification using cement
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Waste packaging
200 l drums
5 to 10 m3 metal boxes
metal ingots
Concrete shells and concrete boxes
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Storage of radioactive waste
• Storage is the holding of radioactive sources, spent fuel or radioactive waste in a facility that provides for their/its containment, with the intention of retrieval. • Storage is by definition
an interim measure.
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Waste Acceptance Criteria (WAC)
• The most common definition of WAC is “those requirements that are to be met by conditioned radioactive wastes, forming packages, to be accepted at an Interim Storage or a Disposal Facility”
• WAC is also important for the different stages of Predisposal activities in a Waste Management System.
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WAC – Technical issues
• Technical issues can be safety and design/operation related.
• Examples of safety related issues are − durability of waste packages− activity limitation− external dose rate− surface contamination.
• Examples of design/operation related issues are − dimensions− mass− mechanical properties− handling requirements− restricted components
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Waste characterization
• Waste characterization has an important role at every stage of radioactive waste management, e.g.• For raw waste,
characterization is needed to decide what processing is required
• For conditioned waste package, characterization is needed to ascertain if the package meets acceptance criteria for storage or disposal.