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Ormai Robbins Intro Management of Challenging Waste
- 1. Management of ProblematicLow and Intermediate Level Radioactive Wastes - Introduction - R. Robbins, P. Ormai Waste Technology Section Division of Nuclear Fuel Cycle and Waste Technology International Atomic Energy Agency Technical Meeting of IPN and DISPONET Networks on the Management of Radioactive Waste Streams that Present Specific Challenges, 28 Nov.- Dec. 2. 2016, VIC, Vienna
- 2. Contents • Problematic waste– definition • Problematic waste – examples • Challenging issues – predisposal – disposal • Alternative disposal options • Meeting objective
- 3. Sources of radioactivewaste NPPs Research Reactors DSRS Front-End Fuel Facilities Hospitals, R&D, Disused Sealed Sources Decommissioning & Environmental Remediation NPP, Research Reactor & Back-End Operations Photos courtesy of Dounreay Site Restoration Ltd & NDA, UK; Cameco Corporation.
- 4. Radioactive Waste Management Ofspecial interest is a category of wastes for which safe, technically correct, efficient, economically attractive and widely acceptable methods for processing and / or disposal are not readily available. Disposal Predisposal Pre-treatment Treatment Conditioning Storage Radioactive Waste Processing Characterization All these wastes must be treated and conditioned as necessary to provide waste-forms acceptable for safe storage and disposal
- 5. International Atomic EnergyAgency Different terms routine waste non-standard, special, unique, problematic, challenging waste Problematic from • predisposal point of view • disposal point of view The problematic waste could be very diverse, and what is considered problematic now at one site may become more or less routine later or at another site or facility. • Problems associated with particular waste could not only be defined by waste characteristics, they could be facility-specific, site-specific or even country-specific. Problems with some waste may be associated with the existing regulatory framework, existing waste management experience, available disposal option, etc.
- 6. International Atomic EnergyAgency Problematic from predisposal point of view Waste may presents a considerable treatment challenge because: • unique composition • large quantity • heterogeneity of the waste • chemical instability (or combination) • Waste characterisation is difficult • without this information forecasts for waste treatment and stabilization are limited • The waste-type fail to meet criteria for acceptance for processing by technologies generally available at the local level • Efficient and cost effective methods for processing is not readily available, wastes do not fit into the other treatment groups Treatment processes may have to be tailored for each waste stream
- 7. International Atomic EnergyAgency Problematic from disposal point of view Waste package • Legacy / historical waste • compliance checking (characterisation) is difficult • Non compliant for the available disposal route • exceeds of permissible activity limitations or mass of chemical constituents, or • exhausts a high portion of permissible activity • Not acceptable for the available disposal route
- 8. International Atomic EnergyAgency Routine waste stream Non-problematic waste package (WAC compliant) Problematic waste stream (pre)treatment, conditioning Non-problematic waste package (WAC compliant) Routine waste stream (pre) treatment, conditioning Problematic waste package (pre)treatment, conditioning Problematic waste stream (pre)treatment, conditioning Problematic waste package Routine waste stream / package Problematic (historic, legacy) waste stream / package Long term storage Predisposal – Disposal link Problematic waste stream pre)treatment, conditioning, disposal Problematic (legacy) waste packages
- 9. International Atomic EnergyAgency Problematic waste packages Reasons: improper material selection, improper processing, QC problems, etc. Important predisposal-disposal link: need for assessing the behavior of waste forms in the disposal environment • Compatibility with the waste stream is a primary consideration in selecting among the available waste forms. • In some cases, lack of compatibility limits the selection (e.g. organic liquids are usually incompatible with grout and can degrade the physical properties of the grout matrix even when present in small amounts)
- 10. International Atomic EnergyAgency Legacy (historical) waste (1) • Produced/processed in the absence of a formal QA- system and WAC; by definition it is of indeterminate quality. • Will need to demonstrate that the waste is acceptable, or can be rendered acceptable, for further processing and disposal. Source; K. Fernando, ANSTO, Australia Corroded historical LLW drums Source; NECSA, SA
- 11. Legacy (historical) waste(2) Source: L. Jones, AECL, Canada Waste mixed, unpacked, uncharacterised, disposed of Source; I. Tarnak, Estonia Briefing on the IAEA Le Trench Project (legacy trench disposal) on Wednesday! Trench remediation, Harwell, UK Source: P. Booth, UK 5 Beryllium pits: 5000 m3 waste Building, laboratory wastes including fume cupboards, glove boxes, drums etc Some of the forms of oxide as a respirable dust can be very toxic to sensitive individuals and Beryllium has a very low Maximum Exposure Limit (MEL).
- 12. International Atomic EnergyAgency Primary waste properties (Typical WAC components) Physical and chemical properties • Physical state • Chemical composition • Combustibility and thermal resistance • Chemical compatibility • Acidity/alkalinity (pH) • Reactive metals and materials • Explosive materials • Toxic materials • Chemical complexing or chelating agents • Hazardous waste • Lead, mercury, cadmium • Gas generation • Asbestos Radiological properties • Total activity and activity concentration • Radionuclide composition (type of radiation, half-life) • Fissile mass • Radiation level (on the external surface of the package) • Contamination (fixed, non-fixed) Biological properties • Putrescible waste • Infectious/pathogenic
- 13. International Atomic EnergyAgency Problematic LILW streams • Nuclear Fuel Cycle Waste • PPE (gloves, suits, wipes etc.) • IEX resins • Liquids with high degree of salinity • Activated components • Contaminated oil, oil sludge, oil with 3H / solvents • Organic complexing agents • Sludge from decontaminating solutions • Reactive metallic waste (alkali metals, alkaline earth metals) • I-graphite waste • Pu residues • TRU/PCM • Scrubber liquors (e.g 129I ) • Fuel element debris • Decommissioning waste (e.g large disused components, asbestos) • RR waste (71 countries) • Wastes from 99Mo production • Decommissioning waste • Beryllium, i-graphite, reactor components, biological shield • Institutional waste • Trash (process & laboratory) • DSRS • Liquid scintillation cocktails • Health care waste (bio-hazardous) • Miscellaneous waste • PCB waste • Compressed gases and aerosols • Ra- / Th-bearing waste • U-waste (e.g U-tetraflouride) • Mixed waste (e.g debris including manufactured objects, plant or animal matter, or natural geologic material) • Paraffin containing waste • Contaminated sites (nuclear tests) • Weapon program, defence related waste • Post accidental waste • large volumes of 3H contaminated water • contaminated soil, debris, foodstuff, water • Depleted U (resource or waste ?) • NORM waste • Legacy waste, historical waste • Complex liquid waste streams • Spent extractant solutions with heavy metal content • Solid miscellaneous waste • DSRS
- 14. International Atomic EnergyAgency Facility / activity Problematic waste Non-nuclear countries Australia 99Mo radiopharmaceutical production - ILW-LL: uranyl nitrate solution containing fission products Denmark Decommissioning of Riso RR and Hot cell - ILW-LL / LLW-LL - solution of uranyl - graphite Estonia Decommissioning of Paldiski NTC and Tammiku RADON type disposal facility - ILW (DSRS, 226Ra contaminated materials, reactor vessels, biological shield tanks. Greece research reactor (GRR-1) - graphite thermal column - beryllium blocks - control rods composed of Ag-Cd- In alloy - 226Ra and 241Am sources Latvia Salaspils RR decommissioning - Beryllium blocks– 4142 kg - i-graphite – 188 kg - reactor pool components (stainless steel, Al, graphite, Be, Pb, titanium) - biological shield components Philippines - Empty teletherapy heads containing DU - Organic liquid scintillation solution Thailand Rare-earth Extraction Plant - Alpha waste: yellow cake and ThO2 - Ba (Ra)SO4 sludge - contaminated solvent (kerosine, TBP solution) Nuclear countries Korea decommission of two RR KAERI - graphite (~ 10 ton) - alpha-bearing organic waste (Uranium-bearing TBP/dodecane) - spent uranium catalyst (~7,000 drum) Hungary RR decommissioning Radon facility - 1200 kg Beryllium - waste retrieved Romania Cernavoda NPP - mineral oil with tritium - machine oil with tritium - scintillation fluid South Africa radioactive waste of health care origin - unknown quantities of 14C, 3H and bio-hazardous components (2500 drums non-processed) France operation and dismantling of GCR reactors defence activities - 17,100 t of irradiated graphite - 4,600 m3 tritium waste - LL-DSRS UK Magnox and AGR reactors Sellafield - fuel sleeves - core graphite from the decommissioning of experimental and prototype - contaminated oil - fuel debris Lithuania RBMK-1500 NPP decommissioning - Irradiated graphite - bituminized waste Sweden NPPs - very large components, such as reactor pressure vessels Germany NPPs, research facilities - Beryllium, sodium, graphite, paraffin containing waste, 3H waste, Th-compounds, DU National examples
- 15. International Atomic EnergyAgency • Pu line carboys • Glass vessels (contents unknown) • Incinerator ash (drummed) • Tractors • Trailers • Cs-137 crane • Pile filters • Tritium furnace liners • Flasks (up to 2 tons) • Building rubble • Asbestos • Pipes • Scaffolding • Pond lamps • Pond tools • Lead castles • Wheels • Drums of oil • Steel tanks • Tank sludge • Mononitrotoluene • Dinitrotoluene • Acid degredation products • Solvent • Asbestos • Hydraulic fluid • Oil • Lead and other heavy metals Source: J. Cruickshank From `simple` to very problematic (complex) cases large quantity, heterogeneous, widely varying characteristics, unique composition, non-characterized, aged, partially or fully buried
- 16. International Atomic EnergyAgency Changing priority in RWM (1) Waste minimisation `Classical` RWM strategy Process and condition the waste for storage and / or disposal New RWM strategy Minimise the volume of the waste to be finally disposed of, by: • partitioning radionuclides • regenerating media • re-using as much of the waste components as possible and economically feasible Recognition: Implementation of any disposal facility for RW is a difficult duty hence disposal facility should be considered as a rare resource (precious asset) Waste minimization programs are mandated by law, and regulations in some countries (e.g USA) waste minimisation, reuse / recycling In addition to reducing volumes and thereby disposal costs, treatment techniques can improve the waste form and, thereby, the performance of a disposal facility.
- 17. International Atomic EnergyAgency Changing priority in RWM (2) Optimisation, integration Because of the variety of processes, techniques and equipment available for different waste streams and waste management steps, optimized technologies have to be selected for each stream and step. To optimize the overall RWM approach, technologies selected for different waste management steps should be combined into an integrated system.
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- 20. Major Predisposal Challenges •Lack of process knowledge • Variable characteristics • Unsegregated wastes • Mixed waste – hazardous items present • Waste previously disposed in unsatisfactory conditions, e.g. trench disposal • Degradation of waste package • Previously conditioned matrix does not meet disposal waste acceptance criteria (WAC) • One-of-a-kind waste streams • No suitable processing technology available • Small volume waste streams – economically unfeasible to build facilities to process these streams • Lack of access to waste processing facilities
- 21. Waste Processing Options Treatment Sorting& Segregation Solid Treatment Technologies · Low force compaction · Supercompaction · Incineration · Metal melting · Pyrolysis Liquid Treatment Technologies · Ion exchange · Filtration · Precipitation · Evaporation Storage Immobilization · Cement · Geopolymer · Polymer · Ceramic · Vitrification Overpack Packaging Conditioning Photos courtesy of Dounreay Site Restoration Ltd and NDA; Sellafield Sites Ltd. and NDA, COVRA N.V.; M. Ojovan, IAEA
- 22. Available Conditioning Technologies ProcessWaste Types Calcination Aqueous liquids Crystallization / Drying Aqueous liquids, Wet wastes: IX resins, sludges, evaporator bottoms Steam Reforming Organic wastes, e.g. IX resins Nitrate wastes Liquid wastes Ceramic processes IX resins, sludges, evaporator bottoms, zeolites, PCMs Sintering Granular dry solids Ceramic processes IX resins, sludges, evaporator bottoms, zeolites, PCMs Sintering Granular dry solids Molten salt processing Wet wastes, such as IX resins, low activity filter cartridges. Dry solid wastes, including combustible, non-combustible compactable, metal, ash, air filter Process Waste Tyeps Graphite annealing / roasting Irradiated graphite Thermo-chemical treatment Solids, such as metals, asphalt, concrete, plastics, polymers Wet solids, such as ion exchange resins, medical waste, biological objects. Granular solids, such as ash residues, calcinates, spent inorganic sorbents, contaminated soils. Carbon with 14C retention (reactor graphite, lubricants, moulds, etc.). Fuel rod zirconium Metal melting Most ferrous and non-ferrous metals Vitrification Aqueous liquids Wet wastes, such as sludges, IX resins, filter media, evaporator concentrates Solids such as soils, sediments, incinerator ashes, asbestos, medical wastes, filter media High-temperature incineration with plasma slagging Combustible solids, wet solids and liquids Small percentage of non-combustible material is acceptable in waste Induction melting Granular dry solids, such as incinerator ash Metallic wastes Molten metal processing Wet wastes, such as IX resins, low activity filter cartridges. Dry solid wastes, including combustible, non-combustible compactable, metal, ash, air filter, asbestos Plasma processing Most waste types, solid and liquid, including non-combustibles
- 23. Waste Hierarchy Decommissioning Facility DesignOperations Photos courtesy of Dounreay Site Restoration Ltd & NDA, UK Waste Minimization Reuse Recycle DisposalLeast Desirable Most Desirable Reducing the amount and activity of radioactive waste to a level as low as reasonably achievable by: – Reducing waste generation at source – Recycle and reuse Occurs at all radioactive life cycle stages
- 24. Examples of ChallengingWaste Streams • Spent ion exchange resins • Sludges • Evaporator concentrates • Aqueous waste e.g. oils or decontamination solutions containing organic complexants • Tritium containing waste • Carbon-14 containing waste • Irradiated graphite • Depleted uranium • Beryllium
- 25. Tritium (H-3) ContaminatedLiquids • t½ = 5,730 years • Mostly commonly occurs as tritiated water, in aqueous sludges, tritiated oils etc. • Tritium is highly mobile in disposal environments – readily diffuses from or through porous waste forms (e.g. cement and geopolymers) and highly volatile so not amenable to thermal processing • Industrial processes exist to remove tritium from heavy water (e.g. in CANDU reactors) – Too expensive to be used on removing low concentrations of tritium from large volumes of waste water (e.g. Fukushima Daiichi or LWRs)
- 26. Modular Tritium RemovalSystem Photos Courtesy of Kurion Veolia • Developed by Kurion Veolia – demonstrated at pilot-scale • Tritiated water is fed into an electrolyser and cracked into gaseous oxygen and hydrogen streams • Gaseous streams are decontaminated to leave pure oxygen and hydrogen/tritium (HT) • Tritium is extracted (catalytic column) in the form of tritiated water (HTO) and stored pending recovery and disposal
- 27. Problematic Liquid WasteStreams • Certain wastes are problematic for glass matrices or existing vitrification process technologies – Waste streams with volatile components, for example I-129 and Tc-99 – Nuclear wastes containing actinides, notably plutonium (surplus weapons Pu and Pu residues) – Lack access to conventional vitrification facilities • Development of new waste form matrices for example ANSTO’s Synroc and other glass ceramics • Development of modular vitrification processes
- 28. Intermediate Level Liquids •Extraction of Mo-99 (precursor of Tc-99m) results in production of intermediate level aqueous waste containing dissolved fission products (Cs- 137 & Sr-90) • Key selection criteria for conditioning method: • High waste loading • Mechanically and physically durable • Amenable to remote handling (hot cell) • Proliferation resistant • High Na concentration will limit waste loading particularly in ceramic hosts • ANSTO developed a process using hot-isostatic pressing (HIP) with a glass ceramic • High waste loading (~26% oxide equivalent) • Better retention of Tc-99 and Cs-137
- 29. In-Can Vitrification • Relativelylow cost alternative to bulk vitrification • Waste (for example spent ion exchange resin) mixed with glass formers • Placed in a container that: – Acts as an ICM – Final disposal container • Advantages – Good for low volume problematic waste streams (spent ion exchange resins, salt cake) – Enhanced incorporation of volatile constituents (e.g. Tc-99) – Good volume reduction – Modular system – Produces waste form in final disposal container • Currently developed to pilot-scale Photos Courtesy of Kurion Veolia
- 30. Predisposal Path Forward •Fully understand the waste characteristics • Develop a national integrated waste management strategy – Understand the legacy, ongoing and future waste inventory – Development of cradle-to-grave radioactive waste management solutions for each waste stream – group ‘like’ waste streams together – Identification of gaps i.e. problematic wastes without predisposal/disposal concepts – Conduct research and development activities to identify viable processing technologies • In the future – begin with the end in mind i.e. do not produce waste streams without a clear processing path and end-point
- 31. From disposal pointof view the most problematic waste streams: • consists of long-lived, highly mobile like 129I and 14C • long-lived, highly toxic radionuclides, especially transuranics (TRU) • The most problematic “TRU” LLW comes mainly from • MOX fabrication • reprocessing facilities (variety of wastes including metal, liquid waste, nitric acid) • Other problematic LILW: • DSRS (LL, Cat. 1-2.) • Irradiated graphite • Ra-bearing waste • Bulky waste • Mixed waste • Nation-specific problematic wastes LILW disposal challenges (1)
- 32. International Atomic EnergyAgency LILW disposal challenges (2) Disposal route is available • The package is non compliant • considered on a case by case basis as a Waiver to the WAC • Introduction of a new waste form (e.g. large disused components, heat generating 60Co sources ) • development of a specific technical requirement for that waste form • Waste volume or activity exceeds the disposal capacity • is the repository expansion possible ? • Waste packages are not acceptable for the existing disposal route • alternative disposal route No disposal route is available • Siting a repository (many challenges) • Develop sustainable concept (disposal) • Derivation WAC Until the final waste disposal strategy and WAC are defined the operator should avoid the adoption of WM technologies that cannot be shown to have a clear benefit in preparing for eventual disposal (predisposal challenge). • Address country-specific challenges
- 33. International Atomic EnergyAgency Sweden: • The two existing entrance tunnels are too small for very large components, such as reactor pressure vessels. Hence, it has been decided to build a third tunnel in SFR. Fast breeder lateral neutron shielding blocks Vessel heads Source: ANDRA Source: SKB Examples for disposal challenges Disposal of large components France (Centre de l’Aube): • Reactor-vessels heads are disposed of in dedicated cells. Conditioning is performed inside the disposal vault. • Adapt existing disposal cells Source: J. Nzimande, Koeberg, South Africa, 2014 • Dedicated disposal cells South Africa (Vaalputs): • The steam generator (SG) replacement project requires the disposal of the six original SGs as radioactive waste. Decommissioning projects are increasing at a rapid pace. The result of this trend means more large pieces of contaminated equipment that do not meet the traditional dimension requirements also need a permanent disposal location.
- 34. Examples for disposalchallenges Disposal of Uranium tails • 1 t enriched (up to 3 - 4%) uranium 7 t depleted uranium (residue material) • Annual production of DU in Germany 2,800 t • Without prolongation of NPP operational life time still 16,000 – 30,000 t DU will be produced (ca. 1015 Bq) • Stored as UF6 • UF6 volatile and aggressive, with water => HF, not disposable • Conversion to U3O8 - Technology is available • Limitation for Konrad: 150 t U-238 • Disposal in another repository (?) Source: Karin Kugel, Federal Office for Radiation Protection (BfS), Germany
- 35. Examples for disposalchallenges Disposal of sodium waste 7 sodium cooling traps from the compact-cooled nuclear reactor in Karlsruhe Sodium and sodium compounds (NaOH, NaH, NaHCO3) Na – self-igniting and aggressive with water, not disposable 6 cooling traps each with a mass of 130 kg sodium 1 cooling trap with 1,700 kg sodium High activity of H-3: in total approx. 1.3·1014 Bq Source: Karin Kugel, Federal Office for Radiation Protection (BfS), Germany Disposal Aim: condition to fulfil the Konrad WAC Initial considerations: Safe encapsulation of sodium Packaging in Konrad-containers Grouting with concrete Further considerations: Cut into pieces Pack into washing baskets Scrubbed in the sodium-washing system
- 36. Examples for disposalchallenges Disposal of graphite waste (1) UK plans • Reactor graphite makes up about 30% by volume of the UK’s inventory of ILW. • There is estimated to be about 15,000 m3 of graphite arisings prior to 2040, mainly comprising operational waste streams (Magnox and AGR fuel sleeves), along with core graphite from the decommissioning of experimental and prototype reactors. • A further 65,000 m3 of graphite is forecast to arise after 2040, comprising core graphite from the final decommissioning of the Magnox and AGR reactors. The disposal concept under development is for a facility comprising of one or more concrete lined, cylindrical disposal cells, sited within the near surface environment at tens of meters depth below ground level. Source: A. Meehan, P. Sibley, Al Johnson J. Lightfoot, D. Jackson , UK
- 37. International Atomic EnergyAgency Examples for disposal challenges Disposal of graphite waste (2) French plans • Inventory: 17,100 t of irradiated graphite (LLW-LL) • Two design options were considered Disposal with reworked capping (SCR) at a depth of around 15 m in a clay layer with low permeability. (this option is mainly applicable to Ra-bearing waste) Disposal with intact capping (SCI) Cells in a thick clay formation at a depth of 50 to 200 m. Access is via a ramp and once the waste is disposed of, the drifts are backfilled The project has run into difficulties. Current situation: ??
- 38. Examples for disposalchallenges Countries with no nuclear program (small inventory) • Permanent storage: not sustainable • Challenging waste types: DSRS (Cat 1-2.), DSRS-LL (Ra, Am), other LLW-LL (legacy), NORM waste • the `standard ` GD designs may be very expensive • multi-national solution (political will and/or public support ??) • ALTERNATIVE (NOVEL, INNOVATIVE) DESIGNS MAY BE NEEDED !
- 39. Alternative disposal options Disposaldesign Waste type Reference Small trench Decommissioning VLLW Japan (o) Highly engineered near surface vault higher activity LLW streams USA (p) Hazardous waste facilities and municipal or industrial solid waste landfills LLW, NORM USA (o) Small diameter borehole (BDC) DSRS Malaysia, Ghana (p) Large diameter borehole high-risk DSRS Medical waste USA (?) Russia USA (?) South Africa (o) Shaft LLW LILW-LL Australia (o) Estonia (p) Purpose-built rock cavern Norway: Himdalen (o) Abandoned mine (rock gallery, tunnel) NORM (Ra-,Th-, U-bearing) LILW Czech: Richard, Bratrství, Hostim (o) Romania: Baita, Bihor (o) Ex-military fort LLW-SL, LL DSRS Poland: Rozan (o) Underground bunker Kazahstan (o) Abandoned underground military objects Albania, Croatia (p) Multi functional facilities near surface + borehole (BDC) near surface-vault +LL waste PHI, Iran (p) Australia (p)
- 40. IAEA BDC: BoreholeDisposal Concept A generic SC has been developed for borehole disposal of Cat. 3–5 sources, and has been completed t for Cat. 1 and 2 sources. • Borehole facilities offer safe, simple, economic alternative for all DSRS • No decrease in safety standards • Small footprint • Broad range of suitable (safe) site properties • Safe implementation with limited resources Disposal of DSRS is a serious challenge in many MSs, often with limited infrastructure and resources. The high specific activity and the long half-life of some of the isotopes in radioactive sources cause problems in fitting some DSRS into the waste disposal schemes of many countries.
- 41. ShaftLDB Purpose-built rock cavern Multi functional facilities Abandonedmine (rock gallery, tunnel) Small trench
- 42. It is worthwhileto exchange advanced information on the ongoing R&D activities in MSs and to facilitate access to the practical results of their application for processing and disposal of specific waste types since that will contribute towards the implementing of novel ideas and for improving the efficiency and general safety of RWM practice in MSs.
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