1 return of experience valerie drake ukaea va drake, ukaea, chapter 13

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RETURN OF EXPERIENCE

Valerie Drake

UKAEA

VA Drake, UKAEA, Chapter 13

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Four European pilot projects

Name ofinstallation

Type ofInstallation

PlaceCountry

AT1 Pilot reprocessingplant

La HagueFrance

BR3 PWR plant MolBelgium

KRB BWR plant GundremmingenGermany

WAGR AGR plant WindscaleU.K.

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Other Major European projects

Name ofinstallation

Type ofInstallation

PlaceCountry

KGR 8 PWR type units GreifswaldGermany

NPP A-1 HWGCRexperimental andpower prototype

JaslovskeSlovak Republic

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AT-1 (Marcoule, France)

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AT-1 General Description

• Pilot plant for reprocessing fast breeder reactor fuel

• shut down 1979 fission product solution

Chop and leach

Fuel dissolution

Spent fuel storage

Uranyl nitrate solution

Plutonium oxide (PuO2)

U and Pu concentration

4th U/Pu separation

cycle

2nd and 3rd extraction

cycle

1st extraction cycle

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AT-1Project Summary

• decommissioned between 1984 and 2001 in five stages:

alpha cellssmall beta-gamma cellshigh active cells using ATENAstorage and fission product cellsfinal clean-up and dismantling

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AT-1 Flowsheet

Storage of the fission product

solutions

1st extraction

cycle

cell 904

cell 900

cell 901

Gaseous wastes ventilation HA

cell 903Cell 902

Chop and leach

Fuel dissolution – cleansing of the gaseous

effluents Solution filtration Spent fuel storage

Washing of the fission product storage tank

Casks arrival

cells 908/909cell 910

Rremoval of solid wastes

Uranyl nitrate solution

Plutonioum oxide (PuO2)

Cell 906cells 950/951cell 952cell 905

cell 907cell 911

Oxalic precipitation calcination

U and Pu concentration

4th U/Pu separation cycle

2nd and 3rd extraction cycle

Transfer siphon mist traps Liquid effluents

storage

911911

911

911

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AT-1ATENA

• Remote dismantling machine with power manipulator

• 6 metre articulated arm

• high reliability

• site specific design

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AT-1Dismantling of high active cells

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AT-1Operational lessons learned(1)

• The working environment should not be used to test unqualified equipment (RD 500)

• ‘Dropping’ dismantled waste into the cells spreads contamination

• Shot-blasting of walls proved lengthy and gave rise to secondary waste

• Need to consider the effect of project time scales on ageing equipment/ systems

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AT-1Operational lessons learned(2)

• Financial incentives to minimise waste production

• Computer modelling of operations

• Cell cleanliness

• Use of standard equipment - availability of spare parts

• Cutting of sheet metal using explosive cords

• Dismantling and cutting using the ATENA machine

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AT-1General learning points

• Good Post Operational Clean Out (POCO) on plant closure

• Dismantle early and rapidly (time = money)

• Commence manual work as soon as possible

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BR3 (Mol, Belgium)

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BR3 General Description

• Type: Pressurized Water Reactor (Westinghouse)

• Power: 40.9 MWth, 10.5 MWe (net)

• Started in 1962, shut down in 1987

• Served as training center for future NPP operators and as test bed for advanced PWR fuel

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BR3 Layout

Steam generator

Re-fuelling pond

Spent fuel pond

RPV

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BR3Project Summary

• 1987: reactor shut down

• 1991: decontamination of the Primary Loop

• 1991-95: dismantling highly active internals(2 sets)

- dismantling of contaminated loops and equipment

- thorough Decontamination of metallic pieces

• 1999-2000: removal and dismantling of the RPV

• 2000-date: decontamination of steam generator, dismantling of reactor loops, concrete

• 2009: final completion

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BR3RPV Removal

• De-couple RPV from primary loop

• Lift RPV into re-fuelling pond

• Re-instate pond integrity

• Cutting of RPV

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BR3RPV Dismantling

Milling Cutter

Turntable

Band Saw

Cylindrical shell: Cut into 9 rings using horizontal milling cutter (tangential steps).Flange: Cut with Band Saw Rings: Cut with Band Saw into segments

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BR3Operational lessons learned(1)

• “As built” drawings are not always correct

• Mechanical methods used to decontaminate concrete is prone to spread of contamination

• Effect on visibility from particulates and insulation

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BR3Operational lessons learned(2)

• Development of dose assessment tool(VISIPLAN)

• 80% reduction in radioactive waste volumes by decontamination(MEDOC process)

• Use of full scale mock-ups for remote work

• Use of proven technology

• Shielding benefits of underwater cutting

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ALARA planning & optimisation

BR3 VISIPLAN model

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BR3General learning points

• Decontaminate plant early after shut down

• Importance of setting-up waste routes

• Importance of planning

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WAGR (Windscale, UK)

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• Type: Advanced Gas cooled Reactor

• Power: 33 MW(e)

• Started in 1963, shut down in 1981

• Served as prototype for UK reactor development

WAGR General Description

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WAGR Layout

Maintenance Cell

RDM Upper housingSentencing Cell

Reactor core and pressure vessel

3 Te. Transfer hoist and slew beams

Upper loading cell

Lower loading cell

Concreting cell

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WAGR Project Summary

• 1981: reactor shut down

• 1993: remote dismantling machine installed

• 1993: waste route complete

• 1994: removal and disposal of 4 heat exchangers

• 1999-2006: dismantling and

removal of core components

• Total cost €55M

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Remote Dismantling Machine

Upper Housing

Lower housing

Shield floor

Turntables

Fixed beam

3 Te Hoist Slew

Beam

Manipulator Mast

Pressure vessel

8 Te. Hoist

Sentencing cell slew beam

Sentencing cell carousel floor

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WAGROperational lessons learned

• Deployment difficulties with some remote tooling

• Simple tooling, thoroughly tested is best

• Develop contingency solutions

• Consider effect of equipment on environmental systems

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WAGRGeneral learning points

• Relationship with stakeholders

• good housekeeping

• efficient waste packing