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Final Meeting of the contracts TW3-TSW-001 and -002 and TW4-TSW-001 and -002

Final Meeting of the contracts TW3-TSW-001 and -002 and TW4-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 17 th , 2006. Outline. Status of decommissioning Decommissioning waste management

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Final Meeting of the contracts TW3-TSW-001 and -002 and TW4-TSW-001 and -002

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  1. Final Meeting of the contracts TW3-TSW-001 and -002 and TW4-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 17th, 2006

  2. Outline • Status of decommissioning • Decommissioning waste management • Metal recycling market • Radioactive scrap metal recycling & reuse • Clearance & recycling standards and regulations • Radioactivity measurement techniques and strategies • Fusion industry implications • Conclusions

  3. Status of decommissioning • An entire generation of nuclear plants are ending the operating life; • Hundreds of thousand of t/a will be produced by nuclear plants decommissioning within next 40 years; • Only a limited volumetric fraction will contain the most of the activity. (99% of radioactivity concentrated in 1% volume). (Spent fuel is excluded) Time distribution for generation of slightly radioactive solid material from USA power reactor decommissioning

  4. Decommissioning waste management • 3 options are envisaged for the radioactive waste: • Clearance, (unconditional, unrestricted release); • Conditional clearance: recycle, reuse in specified application and subject to regulatory control; • No release from regulatory control, (management as radwaste). • Each option has economic impacts due to the associate pricing for handling and disposal. • (average disposal cost in Europe in existing shallow land repositories is ~3000 €/m3) • disposing of slightly radioactive metal from decommissioning in USA could range from 3100 to 16000 US$ /m3 (depending from the repository)

  5. Metal recycling market #1 • World population growth, ~ 9B within 2050, will require resources (including financial capital) to be used efficiently and effectively; • Wastefulness will not be tolerated. The three Rs of Waste Management (Reduce, Reuse & Recycle) will become the basis of a new world philosophy; • Metal, plastic and glass are recycled today in large quantities; • Increase in the consume of recycled metal (~900·106 t/a for steel in 2002). (70% of steel produced in USA in 2003are from recycling); • Recycling allows great energy savings (60-75% for steel, ~95% for aluminium); Steel is gold And we avail of it

  6. Metal recycling market #2 (2) (1) The usual way of recycling steel is by re-melting scraps in basic oxygen furnace(1) with pig iron from blast furnaces, or solely in electric arc furnaces(2).

  7. Radioactive scrap metal recycling #1 • Issue already in the agenda in 80s –90s; OECD-NEA study (1996) on 25 decommissioning projects in 9 different countries showed the following shortcomings: • clearance approach on a “case-by-case” basis; • absence of consistent international release criteria or national clearance standards. • Few thousands of tons of metals are generated from the dismantling of a power reactor (non-radioactive or recyclable fraction  50-70%); • Recycling of metals by re-melting (in electrical induction heating and electric arc furnaces); Mixing with non-contaminated scrap metal up to ~ 20% wt; • Concrete debris are mostly non-contaminated and will pose no health risks.

  8. Radioactive scrap metal recycling #2 • Radioactive Scrap Metal melting allows: • A large reduction in the radioactivity of the final ingot due to dilution and nuclides separation (in the slag and in the off-gas system); • Activity homogenisation and volume reduction; • Stabilised product suitable for final disposal.

  9. Radioactive scrap metal recycling #3 • International studies [OECD-NEA e ANL (USA)] showed advantages of the option recycle/reuse over dispose/replace as far as: • Worker and public health (radiological risk much lower than conventional ones - fatalities and disabling injuries from workplace and road accidents); • Energy and valuable natural resources savings; • Reduced environmental impact.

  10. A portal truck monitoring system commonly used by steel mills to intercept incoming scrap metal Radioactive scrap metal recycling #4 • From the public acceptability perspective both options have problems at the moment.

  11. Clearance & Recycling standards and regulations#1 • Council Directive 96/29/Euratom [Basic safety standards for the protection of the health of workers and the general public against the dangers arising from ionizing radiation, [OJ no. 159, 29.6.1996, p. 1-114]; • Disposal, recycling and reuse of material containing radioactive substances is subject to prior authorization; • Any practice involving radioactivity requiresjustification; • If yes: reporting and prior authorizationor exemption if linked radiological risks are sufficiently low; • Clearance is the removal of radioactive materials or radioactive objects within authorized practices from any further regulatory control by the regulatory body, • The clearance levels are the recommended nuclide specific limits below which authorities could authorize clearance. • They are based on radioprotection criteria.

  12. Clearance & Recycling standards and regulations #2

  13. Clearance & Recycling standards and regulations#3 • Individual doses of some tens ofµSv/a are considered trivial. • To take into account multiple exposures: • Individual dose  <10 µSv/a per practice; • Collective dose  < 1 pers·Sv/a per practice. • Radiological model to derive clearance limits of the single nuclide have to take into account all possible exposure scenarios: ingestion (direct and indirect), inhalation, and external -radiation &-skin-irradiation.

  14. Clearance & Recycling standards and regulations#3

  15. Clearance & Recycling standards and regulations#4 • Documentation issued by international bodies (IAEA, EC,NEA-OECD e US NRC) related to “clearance” criteriaand limits: • IAEA:TECDOC-855 [TECDOC-855] andSAFETY GUIDE No. RS-G-1.7 [SAFETY GUIDE No. RS-G-1.7], • EC: RP89 [RP 89] RP113 , RP114, RP117, RP122 [RP 122] • NEA-OECD [NEA-1996] • US NRC: NUREG-1640 [NUREG-1640] • EC RP 134 [RP134] – relative to the evaluation of the application of the concepts of exemption and clearance for practices according to title III of Council Directive 96/29/Euratom.

  16. Clearance & Recycling standards and regulations#5 Table from EC RP 134: Need for harmonisation of Cls Case of tritium: from 0.4 Bq/g in UK up to 1.0E+6 Bq/g in the Netherlands

  17. Radioactivity measurement techniques and strategies #1 • Aim: ascertain the absence of radioactivity and/or the compliance with proposed limits; • Direct measurement on material or on representative samples, or by other means retained sufficient by the competent national authority; • The objective of keeping individual dose <10 µSv/a entails that dose rates to be measured are a small portion of natural background; need to operate at the lower boundaries of instruments detection; • For nuclides difficult to measure it could be possible to link them to other nuclides.

  18. Radioactivity measurement techniques and strategies #2 • Specify the mass or surface on which average the measurement (distribution not homogenous); • Surfaces of few dm2 and mass of few hundreds of kg (max. 1 m2 and 1 t) may be considered as appropriate for averaging the measurement; • Minimum No. of measurements defined by the regulatory authority (i.e.: wall surface radioactivity); • When measuring the surface activity, it should be considered the “total activity” (removable + fixed surface activity) as well as that penetrated into the material from the surface (i.e.: due to corrosion).

  19. Radioactivity measurement techniques and strategies #3 • Chances to measure g rays from the bulk; • Limitation of the surface activity involves that of the bulk, by simply measuring the g radiation on the surface; • For low energy -rays or for b- and a-emitters the opposite problem might occur; they can go undetected if they are located under rust, corrosion or surface coatings; • Other problems are: the geometrical complexity, the influence of the natural background, the accessibility of the item including their surfaces, and the sensitivity of the instrument relative to the criteria to be met; • At any rate the state of the art in measuring of radioactivity is sufficiently developed to cope with the challenge.

  20. Conclusions • The experience of decommissioning of an entire generation of nuclear facilities will be exploited by future fusion industry, (i.e. for recycling, reuse or disposal). • The real waste management problem in fusion will be relative to the in-vessel components (IVCs). • The fusion industry would have the advantage of being able to use activated metal, as it would be employed in a controlled environment, (radiation fields will be monitored). • It seems more important to demonstrate the feasibility of IVCs recycling from the technical point of view, rather than to perform an economic assessment with the present-day terms. • It would be greatly more important to concentrate the future activities on: • the study of the fusion material and equipment cycle and; • on the regulatory framework, within which recycling of fusion material could be performed.

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