Magnox Ltd is owned by Cavendish Fluor Partnership and operates ...

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

[email protected]

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

15/06/20163

Magnox Harwell Location

15/06/20164

6/15/20165

Harwell history: Pre-1930s Race Horse Stables

6/15/20166

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

6/15/20167

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

6/15/20168

Harwell history: 1957 The problem with keeping the runways….

6/15/20169

Harwell history: 1990s to present day Decommissioning…

Over 140 facilities

removed, 11

reactors

decommissioned,

~23 hectares

delicensed

6/15/201610

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

15/06/201611

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

15/06/201612

15 June 201613

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

15/06/201614

6/15/201615

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

6/15/201616

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…

6/15/201617

Time for Stakeholder Management??

Courtesy Herald Series

6/15/201618

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

6/15/201619

General site clean up

Layer Remediation

300mm Layer Removal

Surveying of exposed surface

6/15/201620

Pit Remediation

Size Reduction

Waste Bag

Beryllium Pit Excavation

A Completed Beryllium Pit

6/15/201621

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

6/15/201622

SSA – Remediation Complete

Tree planting on remediated site

with local schoolchildren

and John Craven!

Western Storage Area

15/06/201623

Contaminant SourcesThe Western Storage Area – Chemical Waste Disposal

Concentrations of Chlorinated Solvents in Groundwater (Oct 2013)

15/06/201625

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

15/06/201626

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”

15/06/201628

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

15/06/201631

Liquid Effluent Treatment Plant and Sewage Farm

15/06/201632

Site Location – LETP AND SEWAGE FARM

15/06/201633

LETP Operations

15/06/201634

Aerial View, Looking South (1990s)

15/06/201635

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

15/06/201637

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

15/06/201643

15/06/201644

Fingerprint Zones

Characterisation Overview

15/06/201645

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

15/06/201646

Infrastructure

15/06/201647

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

15/06/201649

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

15/06/201650

Reinstatement

15/06/201651

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

15/06/201652

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

15/06/201653