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1 RETURN OF EXPERIENCE Valerie Drake UKAEA VA Drake, UKAEA, Chapter 13.

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Presentation on theme: "1 RETURN OF EXPERIENCE Valerie Drake UKAEA VA Drake, UKAEA, Chapter 13."— Presentation transcript:

1 1 RETURN OF EXPERIENCE Valerie Drake UKAEA VA Drake, UKAEA, Chapter 13

2 2 Four European pilot projects

3 3 Other Major European projects

4 4 AT-1 (Marcoule, France)

5 5 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 (PuO 2 ) U and Pu concentration 4 th U/Pu separation cycle 2 nd and 3 rd extraction cycle 1st extraction cycle

6 6 AT-1 Project Summary decommissioned between 1984 and 2001 in five stages: alpha cells small beta-gamma cells high active cells using ATENA storage and fission product cells final clean-up and dismantling

7 7 AT-1 Flowsheet Storage of the fission product solutions 1 st extraction cycle cell 904 cell 900 cell 901 Gaseous wastes ventilation HA cell 903 Cell 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 (PuO 2 ) Cell 906cells 950/951cell 952cell 905 cell 907cell 911 Oxalic precipitation calcination U and Pu concentration 4 th U/Pu separation cycle 2 nd and 3 rd extraction cycle Transfer siphon mist traps Liquid effluents storage 911

8 8 AT-1 ATENA Remote dismantling machine with power manipulator 6 metre articulated arm high reliability site specific design

9 9 AT-1 Dismantling of high active cells

10 10 AT-1 Operational 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

11 11 AT-1 Operational 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

12 12 AT-1 General learning points Good Post Operational Clean Out (POCO) on plant closure Dismantle early and rapidly (time = money) Commence manual work as soon as possible

13 13 BR3 (Mol, Belgium)

14 14 BR3 General Description Type: Pressurized Water Reactor (Westinghouse) Power: 40.9 MW th, 10.5 MW e (net) Started in 1962, shut down in 1987 Served as training center for future NPP operators and as test bed for advanced PWR fuel

15 15 BR3 Layout Steam generator Re-fuelling pond Spent fuel pond RPV

16 16 BR3 Project 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

17 17 BR3 RPV Removal De-couple RPV from primary loop Lift RPV into re-fuelling pond Re-instate pond integrity Cutting of RPV

18 18 BR3 RPV 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

19 19 BR3 Operational 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

20 20 BR3 Operational 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

21 21 ALARA planning & optimisation BR3 VISIPLAN model

22 22 BR3 General learning points Decontaminate plant early after shut down Importance of setting-up waste routes Importance of planning

23 23 WAGR (Windscale, UK)

24 24 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

25 25 WAGR Layout Maintenance Cell RDM Upper housing Sentencing Cell Reactor core and pressure vessel 3 Te. Transfer hoist and slew beams Upper loading cell Lower loading cell Concreting cell

26 26 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

27 27 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

28 28 WAGR Operational lessons learned Deployment difficulties with some remote tooling Simple tooling, thoroughly tested is best Develop contingency solutions Consider effect of equipment on environmental systems

29 29 WAGR General learning points Relationship with stakeholders good housekeeping efficient waste packing

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