Ormai Robbins Intro Management of Challenging Waste
1. Management of Problematic Low 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
3. Sources of radioactive waste
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
Of special 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 Energy Agency
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 Energy Agency
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 Energy Agency
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
9. International Atomic Energy Agency
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 Energy Agency
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 Energy Agency
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 Energy Agency
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 Energy Agency
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 Energy Agency
• 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 Energy Agency
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 Energy Agency
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.
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
Process Waste 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 Design Operations
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
25. Tritium (H-3) Contaminated Liquids
• 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 Removal System
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 Waste Streams
• 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
• Relatively low 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 point of 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 Energy Agency
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 Energy Agency
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 disposal challenges
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 disposal challenges
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 disposal challenges
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 Energy Agency
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 disposal challenges
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
Disposal design 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: Borehole Disposal 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.
42. It is worthwhile to 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.
