1. IAEA
Legacy trench sites
- Aspirations for Le Trench Group -
P. Ormai, H. M. Fernandes
Waste Technology Section
Division of Nuclear Fuel Cycle and Waste Technology
T. Payne
ANSTO – Australia
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. IAEA
• Unpacked waste tumble tipping into shallow unlined trenches
• Waste packaged in a variety of container types and randomly dumped or stacked into the
trenches
Trenches were backfilled using materials removed during trench excavation, compacted, and
graded to create an earthen mound cap necessary to prevent rain water ponding and to
promote runoff.
Early disposal practices (1)
3. IAEA
Early disposal practices (2)
• Disposal in `RADON`- type facilities
Unpacked or packaged in a variety of container types, randomly dumped or stacked into
the prefabricated subsurface vaults
“RADON” facilities in Russia (Source: A. Guskov)
Azerbaijan, Belarus, Estonia, Georgia,, Kazahstan, Latvia, Lithuania, Moldova,
Tadzhikistan, Uzbekistan,…Bulgaria, Hungary
Standard design: near surface vaults (6 m depth), shallow borehole for DSRS
“RADON” facilities in Ukraine (Source: N. Rybalka)
4. IAEA
Evolving recognition: several disposal solutions used before
current modern requirements were established may not meet
all the requirements.
These facilities / sites may be:
• still operational
• operation suspended
• closed down
• abandoned
Early disposal practices (3)
5. IAEA
Concerns
• Siting shortages
• No site selection
• No site characterisation
• Poor design
• Information shortages
• existing information on the site /
facility is deficient (evaluation of the
safety is difficult)
• lack of SA methodology
• Infrastructure shortages
• lack of resources
• handling DSRS
• waste characterisation
• Operational shortages
• no WAC (disposal of long life
waste)
• no QM system (e.g insufficient
record keeping)
• lack of appropriate monitoring
• lack of expertise
• lack of safety culture
• operation for decades with no
modernization to improve
operational safety
• Facility evolution
• more rapid deterioration of the
engineered structures, surface
systems, etc.
Design and construction based on safety criteria of 50’s and 60’s
6. IAEA
Safety of the existing facilities / sites
The fundamental questions:
• Is the facility / site safe? Has it been demonstrated ?
• Is there any safety concern?
• What to do if safety concerns obviously exist?
Different status:
Long term safety has not been demonstrated (or adequacy of the assessment
has been questioned) although safety has been questioned because revisions to
the operating conditions or monitoring results;
Long term safety was (re)evaluated, concerns were identified, but no
corrective actions have been implemented;
Long term safety was (re)evaluated and corrective actions were made or
initiated
safety upgrading measures
waste (partial or full) retrieval
7. IAEA
Legacy trenches exist in many countries (1)
Australia: Little Forest Legacy Site (LFLS)
• 1675 m3 waste: ~150 GBq activity, ~1100 kg
beryllium, ~7 g of Pu
• Waste buried in 79 unlined trenches,
covered with ~1m soil
Source: XX
US, Savannah River
Site Slit Trenches
UK: Legacy Trenches
at Sellafield
Windscale Trenches were unlined
excavations used in the 1950s to
bury LLW and some items too large
for ILW stores
Mexico
Radioactive Waste Storage
Centre (CADER)
8. IAEA
Argentina, Ezeiza
Moldova Georgia, Sakadze
Ukraine
Red Forest” in Chernobyl Exclusion zone
Ukraine
6 State Interregional Specialized Enterprises
(RADON)
Legacy trenches exist in many countries (2)
9. IAEA
Examples of identified issues with legacy sites
Lack of site specific information (1)
Source: NECSA, South Africa
• Inventory and source term
• Design and site layout
• Specific location of emplaced material
• Presence of chemical and other hazards
• Adequate site characterization
• Availability of monitoring data
Thabana (South Africa) trench disposal site start of
operation: 1968
• previously known as ‘Radiation Hill’
• very little is known about selection criteria used
• no WAC (mixed LL, SL, chemically hazardous
waste, DSRS, SF, etc.)trenches have no
license for disposal or “permanent storage”
only a preliminary SA for storage (1996)
• Concerns about its suitability as disposal site
10. IAEA
• 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
Examples of identified issues with legacy sites
Lack of knowledge of trench contents (2)
Source: J. Cruickshank, UK
11. IAEA
Examples of identified issues with legacy sites
Radionuclide releases and plumes (3)
Groundwater contamination, Canada
Source: T. Payne
Tritium plume in groundwater near trenched
area
12. IAEA
Examples of identified issues with legacy sites
Significant surface contamination (4)
Surface Pu contamination,
Australia
Source: T. Payne, ANSTO
13. IAEA
Examples of identified issues with legacy sites
Societal issues (5)
• Changes in land usage
• Inconsistent or variable stakeholder
opinion
• Economic conditions may affect
community attitudes to costs of
remediation
• Loss of records and societal memory
of events
• Unclear responsibility and ownership
14. IAEA
JC Article 12. EXISTING FACILITIES AND PAST PRACTICES
„Each Contracting Party shall in due course take the appropriate
steps to review:
…the results of past practices in order to determine whether any intervention
is needed for reasons of radiation protection bearing in mind that the reduction in
detriment resulting from the reduction in dose should be sufficient to justify the
harm and the cost, including the social costs of the intervention.
…”
Joint Convention on the Safety of SF Management and the Safety of RW
Management
PAST PRACTICES
INTERVENTION
International approach
15. IAEA
Requirement 26: Existing disposal facilities
In the event that any requirements set down in this Safety
Requirements publication are not met, measures shall be put
in place to upgrade the safety of the facility, economic and
social factors being taken into account.
IAEA Safety requirements
IAEA Basic Safety Standards
For chronic exposure conditions:
…protective actions shall be undertaken whenever they are
justified;
The form, scale and duration of any such protective or remedial
action shall be optimised …;
16. IAEA
Corrective measures
All activities undertaken to address actual or perceived issues or
problems associated with legacy disposal for radioactive waste.
Corrective measures generally address one or more of the following
objectives:
• Rectify or improve an existing unsafe condition
• Prevent an unsafe condition from occurring in the future
• Achieve compliance with modified regulatory requirements
• Respond to societal demands
17. IAEA
Engineering Issues
Effects on other components of
the facility and disposal system
Increase or decrease in
disposal volume or other limits
Safety Issues
Regulatory requirements
Worker safety
Public safety
Radiological impacts
Non-radiological impacts
During implementation of
corrective action
During subsequent operation and
closure of facility
Post-closure
Accident situations
Analysis,
Prioritization,
Documentation and
Justification
Implementation Issues
Engineering practicability
Timescale for implementation
Availability of resources
including funds
Stakeholder acceptance
Cost
Estimates and uncertainties
Identification of
preferred corrective
action
Remediation approach (1)
18. IAEA
Systematic approach:
1. Analysis (safety evaluation)
• Legacy waste records (exist? how reliable?....)
• Are further investigations or monitoring necessary?
• Assessment of hazards and risks
• How should uncertainty be dealt with?
• What are the criteria for acceptability of current state, including the
applicable standards in the relevant jurisdiction?
Remediation approach (2)
19. IAEA
Remediation approach (3)
3. Identification of preferred corrective actions (feasibility studies)
• What remedial actions are possible and what are the issues for the regulator?
• Need to disturb waste (re-characterization, reconditioning and repackaging)?
• Choosing between remedial options (data required to underpin decisions).
• How to quantify the risk and the benefit?
• How to estimate the risk for workers and members of the public?
• Optimization and cost-benefit analysis of available options.
• Selection of preferred management and remediation options.
4. Implementation
• Development of a detailed remediation strategy and program.
• Regulatory issues (licensing)
• Address socio-political concerns.
• Constraints
20. IAEA
Constraints
• Technical
• Technical knowledge required for site assessment and remediation alternatives
• Address complex sites
• In absence of a decided end-state some sites may be remediated to an interim state
which may be acceptable if any interim action does not inhibit implementation of a later
action
• Challenging working environment (presence of chemical and other hazards,
constrained space, aging facility, security)
• Political
• Political will-power
• The strength of the imperative for immediate or timely action
• Economical
• Cost / staffing / resources
• Current economic climate can make some projects more difficult to justify
• Societal
• Management
• Interactions between various agencies (operator, regulator)
21. IAEA
Risks associated with remedial actions
Assessment criteria considered
• Public risk
– Long term
– Operational
• Worker risk
– Radiological
– Non-radiological
• Environmental risk
• Monetary risk
• Programmatic risk
(engineering feasibility and project
risk, timescale for implementation)
• Socio-economic risk (Socio-
political acceptability)
The benefits, in terms of risk or dose
averted, should be balanced against
cost, both dosimetric and monetary, for
any proposed intervention.
• Decisions on remediation need to be
robust against uncertainty
• May need sensitivity analyses and
alternative interpretations
• Further data collection or monitoring
may be required to justify expensive
remediation options
22. IAEA
Remediation strategies (1)
• New data (site investigations, re-inventorization) New iteration of SA
• Modified assumptions
• Design changes
• sophisticated cap design
• improvement of the drainage system
• leachate management control
• backfill
• improve local physical containment (reconditioning, repackaging)
• additional EBs (cut-off wall)
• Long-term management arrangements (enhanced environmental
monitoring, longer institutional control, permanent site marker, extend site
boundary, prevent certain activities in the region of the facility, relocate local
inhabitants)
• Modified inventory (removal of waste)
23. IAEA
Remediation strategies (2)
Grouting injection
Subsurface barrier
Engineered cover- Non-intervention
- In-situ options
• Buffer zone
• Extended monitoring
• Engineered cover
• Surface interception
• Subsurface barriers
• Pump and treat
• Drainage channels
• In situ stabilization
(grouting)
Sheffield, Illinois, US
Maxey Flats, Kentucky, US
Drainage channels, engineered
cap, pump and treat, buffer
zone, extended monitoring
West Valley, New York, US
Source: P. Booth, UK
Source: s. Romano, US Ecology
24. IAEA
Various remediation strategies (2)
Trench remediation
Waste retrieval
Waste recovery attempt in 2004 from trenches at
CADER, Mexico
Exhumation of trenches in Los
Alamos, USA
Source: R. A. S. Alvarado, CNSNS
Trench remediation,
Harwell, UK
Source: P. Booth, UK
Trench remediation, Norway Waste retrieval, Estonia
Source: T. Ivo, EstoniaSource: A. Sörlie, NRPA, Norway
25. IAEA
Le Trench (legacy trench) working group
( a project within IAEA Environet and DISPONET Networks)
Activities and objectives
• developing a global inventory of legacy sites
• encouraging preservation of relevant information
• identifying and addressing common issues
• developing methods of disseminating knowledge
• provision of technical assistance or advice
• maintaining relevant expertise
LeTrench Technical Meeting
12 – 16 September 2016
Sellafield - UK
