magnox ltd is owned by cavendish fluor partnership and operates
TRANSCRIPT
Magnox Ltd is owned by Cavendish Fluor Partnership and operates on
behalf of the Nuclear Decommissioning Authority
Land Remediation at
Harwell
Jon Blackmore MSc(ENG), C.Geol, C.Env, C.WEM
Senior Project Manager
Overview• Introduction
• Background to Magnox at Harwell
• Overview of land quality management at Harwell
• Case studies of two completed remediation projects
• Details of the Liquid Effluent Treatment Plant (LETP) remediation
project
• Conclusions
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Magnox Harwell Location
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Harwell history: Pre-1930s Race Horse Stables
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Harwell history: 1935-1945 RAF Airfield
Paratroopers and gliders
left RAF Harwell late on
5th June 1944 as the first
part of D-day operations
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Harwell history: 1946-1990s – Nuclear R&D
GLEEP – the first operational
nuclear reactor in W Europe in
Europe
Fourteen reactors in total,
from dustbin-sized experiments to
25 MW materials test reactors
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Harwell history: 1957 The problem with keeping the runways….
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Harwell history: 1990s to present day Decommissioning…
Over 140 facilities
removed, 11
reactors
decommissioned,
~23 hectares
delicensed
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The future – completion of decommissioning in support Harwell Campus
Diamond Light Source (Synchrotron)
Magnox at Harwell
• Magnox is the site licensee for Harwell
• Magnox’s Parent Body Organisation (PBO) is
the Cavendish Fluor Partnership(CFP)
• CFP awarded a contract by the Nuclear
Decommissioning Authority (NDA) in 2014 for
decommissioning of Harwell, Winfrith and the 10
former Magnox reactor sites
• In contrast to other NDA sites, the Magnox
Harwell site is leased to the NDA by UKAEA
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Land Quality Assessment
• Systematic process followed to identify potentially contaminated land
• Desk studies
• Site investigation, general surveys etc
• Potential liabilities prioritised based on a qualitative risk assessment methodology consistent with CLR11
• Work built into work programme for the site
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Information Management
• IMAGES - Information Management and Geographic
Evaluation System
• Oracle-based database system
• Currently used at Harwell, Winfrith and Dounreay,
wider rollout to Magnox underway
• IMAGES Modules
– Documents, Photos, Buildings
– Monitoring
– Intrusive Survey, Radiation Survey
– Site Assessment (‘Sentencing’)
• Focus on technical data
• Links to GIS
Southern Storage Area
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Southern Storage Area:History• WWII RAF Munitions Store – “the
Bomb Dump”
• 7 hectares
• AERE/UKAEA took over in 1946
• Waste storage
• Waste sorting, sea dump drum packing
• 11 Landfill pits
• “Experiments”
• Wide range of contaminants:
– Beryllium
– Organic chemicals
– Radionuclides
– Asbestos
– Munitions
Southern Storage Area
“Old” Chilton School
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Reasons to remediate?
• Groundwater impact from waste pits
• Hazardous materials on or close to land surface
• Company mission to restore site
• Commercial value of land
• Stakeholder pressure:
– local residents/parents
– Local press…
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Time for Stakeholder Management??
Courtesy Herald Series
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Waste Assay Facility
Beryllium Pits A,B & E Containment
Beryllium Pit D Containment
Chemical Pits
Chilton School
General Area Under Remediation
Site Offices, Hygiene Barriers and
Entrance
SSA - Remediation In Progress
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General site clean up
Layer Remediation
300mm Layer Removal
Surveying of exposed surface
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Pit Remediation
Size Reduction
Waste Bag
Beryllium Pit Excavation
A Completed Beryllium Pit
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SSA Remediation Summary
• The SSA had been characterised to best practice but…– Overall waste volumes x1.5
– LLW volumes x0.5
– Fibrous asbestos burials
– PCBs in old oils in pits
• Munitions expected (“bomb dump”!), but 25 visits by RAF Bomb Disposal team
• Storm damage to containment tents
• 1 in 100 yr. rain levels
• Successful remediation, enabled sale of land
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SSA – Remediation Complete
Tree planting on remediated site
with local schoolchildren
and John Craven!
Western Storage Area
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Contaminant SourcesThe Western Storage Area – Chemical Waste Disposal
Concentrations of Chlorinated Solvents in Groundwater (Oct 2013)
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WSA Background• WSA used for licensed storage, treatment and disposal
of chemical wastes:
– 1970 to 1990s
– 24 Waste Burial Pits
– 4500 m3 of waste
– Hazardous chemical wastes, limited radioactivity
– Disposal was into shallow unlined pits
– Underlying chalk geology
– Major drinking water aquifer
• Remediation driven by groundwater contamination issue
• Detailed planning required due to the nature of the wastes
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WSA Remediation - Site Layout
WSA Remediation
• Remediation successfully completed in 2004, 7 months ahead of
schedule
• No significant accidents
• 15000 drums of waste produced
• 90% sent for landfill disposal
• Most of WSA Waste consigned as hazardous, but 917 drums
classified as LLW – “WSA Difficult Wastes”
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WSA Residual “difficult wastes”
• No disposal route at the time (2005)
• Drum contents subject to a cement stabilisation process
to ensure they remained passively safe
• As a result of processing, more drums were no longer
LLW and were disposed of as hazardous wastes
• 276 remained which were still LLW = “WSA Difficult
Wastes”
WSA Difficult Wastes - Characterisation
• With new waste routes becoming available, characterisation work
commenced in 2012
• Samples analysed to obtain RA fingerprint and chemical content
• All drums subject to high resolution gamma-spec
• Fingerprint from RA sample analysis applied to gamma spec results
• Use of historic data
Disposal of the WSA Difficult Wastes
• Original drums in poor condition,
also over-weight for IP2 rating
• Overpacked into salvage drums for
which certificate of approval
obtained (IP1) and loading plan
• 265 drums consigned to Augean’s
site
• 11 contained PCBs at >50 ppb –
these had to be processed and
then incinerated
• Disposal completed in 2015
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Liquid Effluent Treatment Plant and Sewage Farm
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Site Location – LETP AND SEWAGE FARM
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LETP Operations
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Aerial View, Looking South (1990s)
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History1948 – 2014
• LETP operated to treat effluent
from the main nuclear site. The
treatment process removed
radioactivity before discharge of
the water to the River Thames
• The Sewage Farm was used
primarily for foul sewage
treatment, until site connection to
Thames Water foul sewer in
2003
2014 – 2016
• As the nuclear site ceased
operations, the LETP was
replaced by a smaller plant.
Buildings being demolished to
ground level
LETP AND Sewage Farm – Regulatory Status
• The areas are physically separate from the main Magnox
Harwell site
• The LETP is part of the Nuclear Licensed Site
• The Sewage Farm is included in the area for the site
Environmental Permit for radioactive substances, but is
not part of the Nuclear Licensed Site
• Public right of way (Icknield Way) runs between the two
sites
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Land Remediation Project Objectives
• Removal of contaminated structures and soils
• Clean up such that the Environmental Permit and
Nuclear Site Licence are not needed – there are
specific, very stringent targets set by the Environment
Agency (EA) and ONR respectively
• Site to be suitable for any foreseeable future use
• Chemical contamination will be remediated where
found, but current evidence suggests not a major issue
• Chemical remediation targets based on EA and industry
risk-based guidance
• On completion of project, site will transfer back to direct
control of Harwell Campus
Groundwater
• Limited evidence of radioactivity in groundwater from LETP operations
• Low levels of chlorinated solvents from WSA plume
• Five new boreholes just drilled, replacing five old ones
• Water table can be very close to ground surface –will influence timing of deeper excavations in northern part of site
39
Icknield WayEx-Sewage
Farm Area
Liquid Effluent
Treatment Plant
(LETP) Area
Current Layout
Main Works
Traffic
Route
Public Right
of Way
Diversion
Route
During Remediation
Pond Feature
for Surface
Water
ManagementRe-opened
Public Right
of Way
After Remediation
Zoning
• A key objective of the characterisation is to provide radiochemical
fingerprints to apply to waste arising from the remediation
• The zonation of the site is key to this – during remediation, waste
from each zone will have fingerprint for that zone applied, unless
evidence arises to the contrary
• Complicated by drainage, which will cross zones and may have
different fingerprint
• Based on desk study, 25 zones defined, with drains as a notional
26th zone
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Fingerprint Zones
Characterisation Overview
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Enablers
• An environmental impact assessment was carried out in
2015
• Planning application submitted January 2016, planning
permission granted April 2016
• Service isolations:
– Gas main crossing part of site
– Electricity substation
• Site infrastructure
• Ecological surveys – protected species identified,
programme of work to capture and translocate
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Infrastructure
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Waste• Effective waste management key to
decommissioning and site restoration
• Waste makes up approximately half of the
project cost
• Key aspects:
– Packaging
– Assay
– Storage
– Approvals – Magnox/LLWR/Waste
Operator
– RAMT
– Swift turnaround!
– Loading plans
– QA
– Disposal routes
Remediation
• The remediation work itself relatively straightforward!
• Use of excavators to dig soil, size reduce concrete and
cut up metal items
• Full time health physics presence
• Majority of waste will be placed into builders bags
• Bags checked for contamination, dose prior to transport
to waste assay facility
• Alternative containers for bulk metals, sludges
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Verification
• Monitoring of the excavation until it is believed
remediation criteria met
• Samples taken, area left open pending results
• Coordinate with ONR and EA at this point – they may
want access to take their own samples with respect to
delicensing and permit surrender respectively
• Data captured in IMAGES, delicensing case and de-
permitting cases submitted to ONR and EA
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Reinstatement
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Timescales
• 2015/16: Desk study, detailed designs, planning
application
• 2016/17: Characterisation, enabling works,
procurement, mobilisation
• 2017/18 and 2018/19: Remediation works, waste
processing and disposal
• 2018/19: Reinstatement
• 2019/20: Submit cases to remove Nuclear Site Licence
and Environmental Permit
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Conclusions
• Need to consider non-radiological issues as well
– eg chemicals and munitions
• Effective waste management is vital
• Early engagement with stakeholders will help
• Strong commercial drivers for remediation and
release of land at Magnox Harwell
• Remediation on a nuclear licensed site has
specific challenges…
• But these can be overcome – significant parts of
the former UKAEA land holding have been
released for development following successful
remediation
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