Na冷却小型炉のシステム設計研究; 経済性追求型炉の検討(共同研究)

Conceptual design study of small sodium cooled reactors; 300MWe modular reactor (Joint research)

相澤 康介 ; 近澤 佳隆  ; 臼井 伸一; 此村 守; 安藤 将人*

Aizawa, Kosuke; Chikazawa, Yoshitaka; Usui, Shinichi; Konomura, Mamoru; Ando, Masato*

実用化戦略調査研究の一環として、小型炉の多様な特徴を活かしたナトリウム冷却炉の概念設計を実施している。本報告書では、基幹電源に匹敵する経済性を追及するために、スケールメリットの観点から発電出力を300MWeまで増大させ、プラント寿命中の燃料交換回数の削減及び炉心のコンパクト化のため金属燃料を採用し、また物量の大幅な削減を狙い主冷却系を1ループとした経済性追求型ナトリウム冷却小型炉の検討を行った。主冷却系を1ループ化したことによる課題を整理し、最も厳しくなる事故事象と評価された1次系配管大規模破損に対して過渡解析を実施した結果、原子炉スクラムなしでも炉心健全性が確保できる可能性を示した。崩壊熱除去系の過渡解析を実施した結果、崩壊熱除去系の成立が厳しくなると想定した全ケースにおいて、原子炉スクラム後の炉心健全性が確保できる可能性を示した。

Various conceptual design studies of sodium cooled small reactor have been performed in the feasibility study. In FY2005 study, a 300MWe modular reactor which adopts metal-fueled and 1 loop cooling system in order to pursues economical competitiveness was investigated. Transient analyses were performed to show core safety under the large pipe break accident that was found to be the severest accident in case of a 1 loop cooling system. From the analysis results, it was showed a possibility to maintain the core safety without the reactor scram. Transient analyses of the natural circulation decay heat removal system were also performed, and it was showed a possibility to maintain the core safety after the reactor scram. The in-vessel storage (IVS) was adopt to eliminate the ex-vessel storage and the design of the distribution flow adjustment device in IVS is studied. It was showed that the IVS could be introduced without modifying in the reactor design in FY2004. The rationalization of the fuel handling system is investigated taking advantage of co-location plant in which the reactor, the recycle plant and the fuel fabrication plant are co-located in a site. As a result of rationalization, the volume of the reactor building becomes 0.85 times as much as that of the design in FY2004.