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R Pampin , R Bestwick EURATOM/UKAEA Fusion Association AMEC-NNC Ltd

TW5-TSW-001 monitoring meeting CEN-SCK Mol, June 2006. Study on recycling of fusion activated materials: Identify activation levels, characteristics and decay time requirements of irradiated material (deliverable 3). R Pampin , R Bestwick EURATOM/UKAEA Fusion Association AMEC-NNC Ltd.

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R Pampin , R Bestwick EURATOM/UKAEA Fusion Association AMEC-NNC Ltd

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  1. TW5-TSW-001 monitoring meeting CEN-SCK Mol, June 2006 Study on recycling of fusion activated materials:Identify activation levels, characteristics and decay time requirements of irradiated material(deliverable 3) R Pampin, R Bestwick EURATOM/UKAEA Fusion Association AMEC-NNC Ltd

  2. Background • European Fusion Programme strategy for fusion irradiated waste: • Release from regulatory control of 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the rest • PPCS radioactive waste results: all material cleared/recycled within 100 years, but: • Release criteria: out-of-date IAEA clearance levels (1996) • Lack of detail in the models (e.g. outer components) • Inadequate modelling of particular materials (e.g. LiPb) • Recycling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.

  3. Background • PPCS recycling criteria: some sensible for certain waste streams following certain routes (e.g. re-melting of steels); “complex recycling” limit is crucial but: (a) noticeably over-conservative and (b) depends on route followed!!

  4. Background • IAEA 1996/2004 clearance levels: many changes affect fusion-relevant radionuclides (e.g. 30-fold decrease in Ni-63 level).

  5. Scope and objectives • To review and update PPCS work using: • Up-to-date international clearance regulations: IAEA 2004 • Up-to-date nuclear data: EAF 2005. • Practical recycling criteria: findings of this task. • More accurate modelling methodology (e.g. LiPb flow) and increased level of detail (e.g. TFC materials). • With the aim of: • Determining more realistic amounts and description of waste according to actual processing routes. • Identifying interim decay times required before recycling. • Identifying potential for (a) reduction of waste, and (b) simplification of recycling processes.

  6. manifold HT shield breeder zone LT shield vessel TF coil W armour Computational tools and models • HERCULES code automates 2D geometry + material modelling of tokamak power plants, coupling: • MCNP neutron transport • FISPACT transmutation + EAF libraries PPCS-AB HERCULES model.

  7. vessel TF coil Computational tools and models a b c d e f PPCS PPCS (a)(b)(c) (d) (e) (f) • VV front casing  316ss • VV radial plates  316ss • VV rear casing  316ss • TFC front casing  316ss • TFC winding pack  316ss, SC cable, incoloy, epoxy • TFC rear casing  316ss

  8. Preliminary results • New IAEA levels  increased amounts of material to be recycled: OB VV and IB TFC. • Segregation alleviates this.

  9. Preliminary results • Cooling times of PPCS-AB and PPCS-B individual constituents and materials and average components; in preparation.

  10. Preliminary results • PPCS-AB results (general): • 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 seems imperative  reuse in fusion plant?

  11. Preliminary results • PPCS-AB results: 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

  12. Preliminary results • PPCS-B results (general): • In-vessel: again, all Eurofer and LTS neutron shield (ZrH) show < 2 mSv/h in ~75 years. • In-vessel: Li4SiO4, Be and W armour, however, do not meet this target  Li4SiO4and Be dose entirely due toimpurities: control of these would meet target Co, Ni, Nb, Mo, Eu, Sm, Gd, Tb, Pt, Ir, Pb, U, Th, Bi, Ag, Cd, Ba, Tl, Co, Nb

  13. Summary • 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/recycling potential and interim decay times. • Results: • new IAEA levels increase amount of material to recycle. • PPCS analyses over-conservative: most material suitable for “simple-recycling” after < 75y cooling time. • control of impurities crucial, not only in steels but also for e.g. Be and Li4SiO4: requirements being developed. • Further input: definition of “non-simple” recycling routes and radiological criteria. • Draft report & radiological data available shortly raul.pampin@ukaea.org.uk

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