Management strategy for radioactive waste in the fusion demo reactor

Youji Someya, Kenji Tobita, Hiroyasu Utoh, Nobuyuki Asakura, Yoshiteru Sakamoto, Kazuo Hoshino, Makoto Nakamura, Shinsuke Tokunaga

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

We have considered a strategy for reducing the radioactive waste generated by the replacement of in-vessel components, such as blanket segments and divertor cassettes, for the fusion DEMO reactor. In the basic case, the main parameters of the DEMO reactor are a major radius of 8.2 m and a fusion power of 1.35 GW. Blanket segments and divertor cassettes should be replaced independently, as their lifetimes differ. A blanket segment comprises several blanket modules mounted to a back-plate. The total weight of an in-vessel component is estimated to be about 6,648 ton (1,575, 3,777, 372, and 924 ton of blanket module, back-plate, conducting shell, and divertor cassette, respectively). The lifetimes of a blanket segment and a divertor cassette are assumed to be 2.2 years and 0.6 years, respectively, and 52,487 tons of waste is generated over a plant life of 20 years. Therefore, there is a concern that the contamination-control area for radioactive waste may need to increase due to the amount of waste generated from every replacement. This paper proposes a management scenario to reduce radioactive waste. When feasible and relevant, back-plates of blanket segment and divertor cassette bodies (628 ton) should be reused. Using the three-dimensional neutron transportation code MCNP, the displacement per atom (DPA) of the SUS316LN back-plates is 0.2 DPA/year and that of the F82H cassette bodies is 0.6 DPA/year. Therefore, the reuse of back-plates and cassette bodies would be possible if re-welding points are arranged under neutron shielding. We found that radioactive waste could be reduced to 20 % when tritium breeding materials are recycled. Finally, we propose a design for the DEMO building that uses a hot cell and temporary storage.

Original languageEnglish
Pages (from-to)423-427
Number of pages5
JournalFusion Science and Technology
Volume68
Issue number2
DOIs
Publication statusPublished - 2015 Sep 1

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Materials Science(all)
  • Mechanical Engineering

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    Someya, Y., Tobita, K., Utoh, H., Asakura, N., Sakamoto, Y., Hoshino, K., Nakamura, M., & Tokunaga, S. (2015). Management strategy for radioactive waste in the fusion demo reactor. Fusion Science and Technology, 68(2), 423-427. https://doi.org/10.13182/FST15-101