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Kick Off Meeting of the contracts TW5-TSW-001 and -002

Kick Off Meeting of the contracts TW5-TSW-001 and -002. ENEA part of the Art.5.1.a. task, and reminder of former results and reports L.Di Pace ENEA CR Frascati. Garching, January 18 th , 2006. Outline. Aim of the task; Deliverable 1; Deliverable 6; Schedule. Aim of the task.

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Kick Off Meeting of the contracts TW5-TSW-001 and -002

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  1. Kick Off Meeting of the contracts TW5-TSW-001 and -002 ENEA part of the Art.5.1.a. task, and reminder of former results and reports L.Di Pace ENEA CR Frascati Garching, January 18th, 2006

  2. Outline • Aim of the task; • Deliverable 1; • Deliverable 6; • Schedule.

  3. Aim of the task As shown by the PPCS study, all or most of the active materials arising from the operation and decommissioning would be suitable for recycling, after up to 100 years of intermediate storage. Radiological criteria, mostly based on dose rates, have been commonly used to determine if materials would be candidates for recycling. However it is not clear conditions at which recycling, for example in fabrication of components for new fusion power plants, would actually be feasible. Open questions include the availability of suitable processes, the ability to process active material and fabricate new components using RH techniques, and the economic viability of such processes. Study on Recycling of Fusion Activated Materials;

  4. Deliverable 1 • This deliverable will define components and materials involved and determine volumes & masses for PPCS Model AB considering the main boundary conditions. • Data from the report UKAEA/TW4-TRP-002 Deliverable 2e Jan 2005 [UKAEA/TW4-TRP-002] and related neutron transport and activation calculations available on CD.

  5. Deliverable 1

  6. Deliverable 1

  7. Deliverable 6 • Define interim clearance levels for the missing radionuclides not included the IAEA Safety Guide (SG) No. RS-G-1.7 [IAEA RS-G-1.7]. • The recent IAEA SG No. RS-G-1.7 has defined “Application of the Concepts of Exclusion, Exemption and Clearance”, providing specific activity levels for exemption and clearance, dividing radionuclides of natural origin from the artificial ones. • The list of artificial radionuclides for which clearance levels are given includes about 260 nuclides, while the previous IAEA TECDOC-855 was able to provide (directly or indirectly) clearance levels for ~ 1650 nuclides. • The proposal is to provide interim clearance levels for missing radionuclides based on the application of the Radio Toxicity Index to derive clearance level (see reference [ICEM03]).

  8. Deliverable 6 • Preliminary comparison done by ENEA between CLs IAEA TECDOC-855, Safety Guide (SG) No. RS-G-1.7 and EC RP 122 • 1 [clearance comparison new] using a spread-sheet; • 2 [ENEA TR 135.doc] by dedicated ANITA calculations.

  9. Deliverable 6 • Preliminary comparison between CLs of IAEA TECDOC-855 and SG No. RS-G-1.7 from paper “The Feasibility of Recycling and Clearance of Active Materials from Fusion Power Plants” by M. Zucchetti, L.A. El-Guebaly, R.A. Forrest, T.D. Marshall, N.P. Taylor, K. Tobita [ICFRM-12] Clearance index of material from part of the VV of PPCS Plant Model C

  10. U has been the basis of the fission power industry; It is found in nature in concentrations from 0.1 to 1%; As U is radioactive and quite common in the earth’s crust as ore (U3O8), it might be used as a benchmark for comparing potential fusion radioactive waste. For this comparison U ore with 1% is assumed (˜100% U-238). U-238 specific activity= 1.24x107 Bq/kg. U ore (1% of U-238) the specific activity is 1.24x105 Bq/kg. The ingestion dose conversion factor of U-238, relevant to the public, is 4.50x10-8 Sv/Bq. Therefore, the radio-toxicity of uranium ore (at 1%), is 5.6x10-3 Sv/kg. U-238 radiotoxicity is 100 times larger: 5.48x10-1 Sv/kg. We define the Toxicity Index (TI) as the radio-toxicity of any substance relative to that natural uranium ore. Deliverable 6 Definition of a Toxicity Index [ICEM03]

  11. Deliverable 6 • Toxicity Index for PWR spent fuel(actinides) Typical PWR spent fuel contains ~ 9 g of actinides (mostly Pu-239) and about 35 g of FPs per kg of fuel. • Pu-239 should represent the greatest risk to future generations. • Pu-239 has been assumed to account for the entire mass of actinides. This is equivalent to (9/239) 0.0376 moles or 2.27x1022 atoms. t1/2 of Pu-239 = 24,100 years, hence, the radio-activity in the 1-kg sample is 2.07x1010 Bq. • The ingestion dose conversion factor for Pu-239 is 2.50x10-7 Sv/Bq. The PWR spent fuel radio-toxicity is 5.17x103 Sv/kg – almost 106 times the uranium ore TI. • TI for PWR spent fuel (due to actinides) decreases with time, as Pu-239 has a short half-life, relative to that (4.5 billion years) of U-238 At ~ 500,000 y it becomes the same radio-toxicity of the natural U ore.

  12. Deliverable 6 • Toxicity Index for spent fuel (fission products) Tc-99, I-129 and Sn-126 have the largest radiotoxicity. Their TI is at least one order of magnitude lower than U-238 and  four orders of magnitude lower than Pu-239. Cs-137 and Sr-90 not taken into account due to their short t1/2.

  13. Deliverable 6 Sanity check of IAEA TECDOC-855 and EC-RP 122 CLs of the RTI by spreadsheet using RTI < 0.001 as preliminary clearance level has started.

  14. Schedule From note by V. Massaut dated October 6th 2005 extension From ENEA subtasksummary page issued on Nov. 10 th

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