報告書番号

T03058

タイトル（和文）

燃料無交換密封型ナトリウム冷却小型高速炉（４S）概念

タイトル（英文）

The Sodium Cooled Small sealed Fast Reactor (4S) with non-refueling

概要 （図表や脚注は「報告書全文」に掲載しております）

送電網の脆弱な地域や孤島でのエネルギー供給、多様なエネルギー供給スタイル、海水淡水化等に対応できる簡素で超長寿命な小型炉の開発ができれば、近未来の有望な選択肢になりうると考えられる。当所では、昭和63年より安全性とメンテナンス性の高い小型高速炉（４S）の開発を実施しいるが、近年の国内外の４S炉への高まる期待を背景として、早期実用化に向けた改訂概念の構築を実施している。本報告では、炉心寿命を30年に延長した1万ｋWループ型４S炉（4S-10ML）の概念について述べる。建設コストの削減のためプラント形式をループ型とし、蒸気発生器、中間熱交換器、電磁ポンプを一体化した合体機器を採用している。また、静的除熱系そして、原子炉容器、合体機器容器外表面から空気の自然対流により除熱する独立２系統のシステムを採用している。CERESコードを用いた過渡解析を実施し、これらの設計妥当性を確認した。

概要 （英文）

CRIEPI has been developing the 4S reactor (Super Safe, Small and Simple reactor) for application to dispersed energy supply and multipurpose use. Electrical output of the 4S reactor is from 10MW to 50MW, and the core lifetime without refueling is from 10 to 30years. 30year core lifetime can be achieved with the 10MWe 4S (4S-10M) reactor.All temperature feedback reactivity coefficients, including coolant void reactivity, of the 4S-10M are negative during the 30year lifetime. The pressure loss of the reactor core is lower than 2kg/cm2 to enable effective utilization of the natural circulation force.To suppress the influence of the scale disadvantage, loop-type reactor design is proposed as the candidates for the 4S-10M. The size of the reactor vessel is miniaturized by adopting the loop type as a nuclear system, and 2.5m in diameter and 14m in height have been achieved (4S-10ML). An integrated equipment which includes primary and secondary electromagnetic pumps (EMPs), an intermediate heat exchanger (IHX) and a steam generator (SG) is proposed and is collocated by the reactor vessel.The decay heat removal systems of 4S-10ML consist of the reactor vessel air cooling system (RVACS) and SGACS (a similar system to the RVACS, air cooling of the outside of the integrated equipment vessel). They are completely passive systems. A step mat structure and the horizontal aseismatic structure are adopted to reduce the construction cost of the reactor building.4S-10ML has unique features in the cooling systems such as integrated equipment and two separate passive decay heat removal systems which operate at the same time. To evaluate the design feasibility, the transition analyses were executed by the CERES code. The design concept of the 4S-10ML and the results of the plant transition analyses are described in this report.

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