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Study on recycling of fusion activated materials: Identify activation levels and decay time requirements of irradiated material (deliverable 3) R. Pampin EURATOM/UKAEA Fusion Association TW5-TSW-001&002 final meeting Culham Science Centre, October 2006
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 2/17Background European Fusion Programme strategy for fusion irradiated waste: Release from regulatory control mildly activated material, usually lifetime, bulky, outer components: TFC, VV, LTS. Recycle within the nuclear industry (fission/fusion) the rest. PPCS radioactive waste results: all material cleared/recycled within 100 years, but: Release criteria: out-of-date IAEA clearance levels (1996). Lack of detail in the models (e.g. outer components). Inadequate modelling of particular materials (e.g. LiPb). Recycling criteria based on radiological parameters only, which were imprecise and over-conservative.
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 3/17Background IAEA 1996/2004 clearance levels: many changes affect fusion- relevant radionuclides (e.g. 30-fold decrease in Ni-63 level). TW5-TSW-002 D1 report on implications, TW5-TSW-001 D3 report on specific effects on PPCS-AB.
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 4/17Background PPCS recycling criteria: some sensible for certain waste streams following certain routes (e.g. re-melting of steels); “complex recycling” limit is: (a) noticeably over-conservative and (b) uncertain: depends on route followed ! waste categorisation criteriacontact dose (mSv/h) decay heat (W/m 3 ) CI Permanent disposal (PDW)> 20> 10 Complex recycling (CRM)2 – 201 – 10 Simple recycling (SRM): remote hands-on < 2 < 10 -2 < 1 Clearance< 1
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 5/17 Scope and objectives To review and update PPCS work using: Up-to-date international clearance levels: IAEA 2004. Up-to-date nuclear data: EAF 2005. Practical feasibility criteria: findings of this task. More accurate modelling methodology (e.g. LiPb flow) and increased level of detail (e.g. TFC and breeder materials). With the aim of: Determining more realistic amounts and activation features of the material inventory. Identifying interim decay times required during recycling. Identifying potential for (a) reduction of waste, and (b) simplification of processes.
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 6/17 Material inventory PPCS-AB based on the HCLL blanket concept, PPCS-B based on the HCPB blanket concept.
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 7/17 Industry experience Distinction between recycling and refurbishment: Refurbishment: little or no processing, on-site, immediate or early reuse in the fusion plant (e.g. LiPb, ceramics). Recycling: greater processing, off-site, later reuse in the nuclear industry in general. Recycling strategies in the industry exist for: Very low activity: fabrication of simple components. Very high activity: de-activation and re-fabrication of internals. Recycling routes envisaged for all PPCS-AB and PPCS-B materials (TW5-TSW-001 B report).
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 8/17 Radiological levels Use radiological levels to ascertain storage times needed for the activity to decay to levels facilitating recycling processes: Clearance: C.I. Lower RH needs: contact dose rate. Lower cooling needs: decay heat rate. Easier transport: ?
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 9/17 Computational tools and models
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 10/17 Results: clearance New IAEA levels increased amounts of material to be recycled: OB VV and IB TFC. Time scales: few years OB, few decades IB. Segregation alleviates this.
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 11/17 Results: refurbishment Refurbishment of LiPb is possible and reduces considerably the amount of operational waste (from 124000 to 97000 tonnes). PPCS-B ceramic breeder and other materials also possible, but much lower impact strategic value?
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 12/17 Results: recycling PPCS-AB results: Ex-vessel: most materials, individually or as TFC, VV and LTS, show contact dose rates < 2 mSv/h (earlier OB than IB). Ex-vessel: many of these show < 0.01 mSv/h after suitable decay time (few years OB, several decades IB). In-vessel: poloidal variation is negligible. In-vessel: all Eurofer and LTS neutron shield (WC) show contact dose rates < 2 mSv/h after ~75 years. In-vessel: LiPb breeder and W armour still exceed 2 mSv/h after 100 years: Dominant nuclides arise from Pb and W isotopes, hence impurity control not very useful in this case! isotopic separation needed.
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 13/17 Results: recycling - impurities W and LiPb PPCS specifications contain many impurities: (a) manufacturer limits, (b) detection limits. Co, Ni, Nb, Mo, Eu, Sm, Gd, Tb, Pt, Ir, Pb, U, Th, Bi, Ag, Cd, Ba, Tl, Co, Nb
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 14/17 Results: recycling - impurities PPCS-B results: In-vessel: again, (nearly) all Eurofer and LTS neutron shield (ZrH) show < 2 mSv/h in ~75 years. In-vessel: Li 4 SiO 4, Be and W armour, however, do not meet this target Li 4 SiO 4 and Be dose entirely due to impurities: Co, Ni, Nb, Mo, Eu, Sm, Gd, Tb, Pt, Ir, Pb, U, Th, Bi, Ag, Cd, Ba, Tl, Co, Nb
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 15/17 Results: decay times component / constituent / material10 4 mSv/h100 mSv/h2 mSv/h0.01 mSv/hCI < 1 OB TFC / case rear / 316ss<1d OB TFC / radial plates / 316ss<1d OB TFC / case front / 316ss<1d 2y45y OB TFC / epoxy-glass / 316ss<1d OB TFC / conduits / incoloy<1d OB TFC / cable / SC strand<1d OB VV / rear wall / 316ss<1d 10y45y OB VV / radial plates / 316ss<1d 5y50y>1000y OB VV / front wall / 316ss<1d25y58y>1000y OB LTS / structure / eurofer180d25y50y>1000y OB LTS / neutron shield / WC10d15y55y>1000y blanket / manifold / eurofer15y45y80y>1000y blanket / BZ / eurofer10y35y70y>1000y blanket / BZ / LiPb (5 fpy)120d15y90y>1000y blanket / BZ / LiPb (30 fpy)120d25y>1000y blanket / FW / eurofer15y45y80y>1000y blanket / armour / W5y45y500y>1000y
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 16/17Summary Upgrading PPCS work on PPCS-AB and PPCS-B radioactive waste analysis using recent regulations, new nuclear data, improved modelling and realistic recycling scenarios. Assess clearance/refurbishment/recycling potential and interim decay times. Results: new IAEA levels increase amount of material to recycle; clearance is achieved within few years (OB) or few decades (IB); most recycling material below 2 mSv/h after ~75y of decay; are these acceptable time scales?
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 17/17Summary Three key issues to optimise fusion recycling strategy by reducing amount of material, secondary wastes and/or radiological levels: Segregation of materials Refurbishment Impurity control Further work: Shielding issues, particularly in PPCS-B Transport requirements? New categorisation? Radioactivity build-up due to (a) impurities and (b) reuse. www.fourmilab.ch/earthscr/
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 18/17 Fusion materials strategy – open
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 19/17 Fusion materials strategy – closed
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TW5-TSW-001 final meeting, Culham Science Centre, October 2006 20/17 Fusion materials strategy: radiological levels and classification criteria? – simple transport RHR – complex transport
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