FUSION REACTOR RADIOACTIVE WASTES: results, recycling, open issues and R&D

1. FUSION REACTOR RADIOACTIVE WASTES: results, recycling, open issues and R&D • Outline • Introduction • Radioactive waste from Fusion Reactors • categorization and quantification • acceptability in EU repositories • recycling (operating experience, open issues) • Strategy and R&D • Conclusions W.Gulden, S.Ciattaglia EFDA Close Support Unit, S&E Field, Garching Germany

2. Introduction • The four (+1) conceptual design for commercial fusion power plants differ in their dimensions, gross power and power density but • All models meet the overall objectives of the PPCS: design, safety, economics. Confirmed the intrinsic safety characteristis of all the models • Comprehensive safety analysis of PPCS has showed • “No evacuation” criteria is met with margin also in case of BDBA driven by internal events • Intrinsic-passive safety features have been confirmed also from the bounding accident sequence analyses • Model B, BDBA LOFA + in-vessel LOCA provides the largest environmentalsource terms (well below the evacuation limit: 0.42 versus 50 mSv) • ORE needs attention • Radioactive wastes amount are significant

3. Radioactive waste from fusion reactors • The fusion radioactive wastes are characterised by low heat generation density and low radiotoxicity. • Therefore recycling could be a viable option • Storing the fusion radioactive materials for 50-100 years on the plant allows reduction of radioactivity level waste masses • Their amount is significant in terms of amount and volume • Radioactive wastes represent a very important aspect with respect to • Cost • Licensing • Public acceptance Therefore significant effort have to be pursued in order to reduce their amount

4. Plants main features Blanket DV

5. Decay Heat Models A & B

6. Activation of tokamak structures and components Specific activity of the mid-plane outboard first wall in four Plant Models Dominant radioisotopes • H3, Be10, Ni 63, C14, Co60, Nb94, Ag108m,

7. Categorisation and quantification • Evaluated the operational and decommissioning waste quantity • A useful classification considered till now (waste as PDW, CRM, SRM, NAW) is under discussion in order to • take into account the operating experience with NPP wastes • Include the limits of the actual repositories • consider the possible results of a dedicated R&D programme for Fusion waste recycling

8. Waste Management: evaluation and categorisation Wastes from model B For ALL the Models: • Activation falls rapidly: by a factor 10,000 after a hundred years • Significant contribution to SRM and CRM from operational wastes • Potentiality to have no waste for permanent repository disposal • Presence of tritiated +  activated wastes too

9. Waste Management: masses

10. Acceptability in EU repositories • If no recycling is planned, the amount of wastes to be disposed after 100 years, is equal to the CRM+SRM amounts • Suitability and capability analyses of the final waste repositories in a few EU countries to store the PPCS wastes were performed (Konrad and Gorleben in Germany, SFR and SFL 3-5 in Sweden, CSA in France, El Cabril and DGR in Spain) • With reference to Model B and German regulations, the fusion reactor waste can be all disposed in Konrad. For a few ones, detritiation is necessary to meet the relevant limits

11. Recycling Present operating experience basically limited to SRM • the melting process is applied in fission to homogenize the material (easy to measure), to separate the contamination from the base melt and for a volume reduction (~80%) • melting of slightly radioactive metallic materials is well developed for NPP on materials with low activities, 200 Bq/g as average (limit from ORE to the staff) • an activity level of 1000 Bq/g should be feasible to handle without remote control • some melting facilities are set up to perform “hands on” recycling; only the furnace is in some cases fed by an automatic system. Others are mostly remote controlled, but some operations demand still the operator intervention • the development of a reliable melting facility completely remote controlled is feasible (some R&D is necessary) • materials treated up-to now: Al, Stainless Steel, Carbon Steel, Pb, Cu, Zn, Brass • the products of a melting are simple ingots; if the material is re-used afterwards it is melted again and mixed with other materials • the melting facilities are equipped with test furnaces which can be used for test on fusion materials. Such tests will already give an idea of the applicability of the melting process in fusion recycling

12. Recycling Open Issues The NPP waste recycling techniques are not mature/ extendible to Fusion wastes • Limits (Activity) too severe, high dose rate even after 100 years of decay : needs of RH • The materials treated up to now are limited and the products are simple (e.g. ingots) • The tritium present in the fusion materials is a problem for the off-gas treatment • Some fusion materials can not be submitted to the melting process (i.e. those joined by special bonding techniques). Other techniques are necessary to be developed During fabrication the fusion materials are submitted to sophisticated testing Some parameters are not yet known when using recycled materials:  Influence of the impurities  Influence of the build up of activation products  Influence on material properties • Dose rate and activity level • As RH is unavoidable, the recycling process could be done immediately (i.e. for operational wastes) or after decommissioning: here a decay period can have a lot of advantages

13. Decay 60 d Decay 1 y Decay 10 y Activity of the fusion materials in comparison with the activity limits of the present recycling facilities Decay time

14. Strategy and R&D • show to the public that recycling can be applied on fusion materials and there is no waste burden for future generations. (Future generations can then decide whether recycling is economically acceptable at that time) • the material cycle of the fusion material and equipment should be studied in detail. Where necessary and if possible, the material design could be adapted for easy recycling afterwards • There are still many years before the production of Fusion reactor wastes: an R&D plan has to be launched • Benefiting from NPPs waste recycling as far as possible • Defining an ad-hoc programme considering the peculiarities of Fusion Wastes • Close feedback with designers of structural components to take into account the waste issue in their R&D programme at the highest importance

15. R&D 2005-2006 2 tasks are going to be launched Study on Recycling of Fusion Activated Materials • strategies, feasibility and limitations for recycling structural material • detritiation needs, the relevant technique available and/or their feasibility for the most relevant tritiated components • consideration about the cost of recycling considering a few significant scenarios • limitations to the practical recycling of fusion materials, possibly leading to a re-assessment of the criteria to be adopted in the categorisation of waste materials from a fusion power plant • proposal for a mid-long term R&D step by step plan in order to implement the recycling at the maximum extension possible Complex Recycling of Fusion Wastes • a completion of the status and what is on going or planned in the fission industry about recycling/reuse of radioactive waste. Extrapolation to fusion power reactor wastes and feasibility of recycling and reuse of fusion materials A big effort is necessary in the mid-long term

16. Conclusions • The four(+1) PPCS conceptual design for commercial fusion power plants differ in their dimensions, gross power and power density • All models meet the overall objectives of the PPCS: design, safety, economics • Comprehensive safety analysis of PPCS has showed • “No evacuation” criteria is met • Intrinsic-passive safety features has been confirmed • Model B, BDBA LOFA + in-vessel LOCA provides the largest environmentalsource terms • ORE needs attention • Wastes amount are significant but they are characterised by low decay heat and low radiotoxicity.There is the potentiality to have no need of permanent disposal waste after 100 years from shutdown if complex recycling is applied

17. Conclusions: issues and relevant R&D • Most of the open issues are relevant to the short life time of first wall components • This issue is leading most of the future R&D Physics • advanced plasma scenarios (improved confinement), in particular • good confinement regime with divertor tolerant ELMs • regimes with large fraction of plasma current is driven not inductively • control of plasma transients: ELMs, VDEs and disruptions • SOL, particle exhaust and control Materials&components • optimisation of low activation martensitic steels, use of ODS • development of more advanced materials (e.g. W as structural material and SiC/SiC) • He cooled divertor • development and test of blanket and divertor systems • development and qualification of RH Safety • Control of dust and tritium in the VV (source terms) • Lack of operating experience (Reliability of prototypes, ORE minimisation) • Waste management: quantity of operational waste, tritiated +  waste disposal • Detritiation • Recycling

18. Conclusions: issues and relevant R&D • Answers expected from • ITER operation • EFDA R&D technology programme • DEMO power plant study • Strategy and R&D on reactor fusion wastes • Benefit from Recycling of NPP wastes as much as possible • Detritiation needs and relevant techniques • Reduction of wastes as one of the power plant design criteria of highest importance • R&D on existing/modified recycling facilities with reference to fusion specific wastes • RH development • Cost considerations-optimisations Reduction of waste is possible through a mid-long term strong-focussed R&D programme