Sodium experiments on decay heat removal system of Japan sodium cooled fast reactor; Start-up transient of decay heat removal system

大型ナトリウム冷却高速炉(JSFR)の崩壊熱除去系に関するナトリウム試験; 崩壊熱除去系の起動特性

上出 英樹 ; 小林 順 ; 小野 綾子 ; 木村 暢之; 宮越 博幸; 渡辺 収*

Kamide, Hideki; Kobayashi, Jun; Ono, Ayako; Kimura, Nobuyuki; Miyakoshi, Hiroyuki; Watanabe, Osamu*

大型ナトリウム冷却高速炉の実用化を目指し、完全自然循環方式の崩壊熱除去システムに関する研究開発を進めている。本報告では、これまでに設計例の少ない中間熱交換器に挿入する形式の崩壊熱除去用冷却器(PRACS熱交換器)の伝熱特性並びに1次冷却系と崩壊熱除去系の自然循環に関するナトリウム試験を実施した結果を示す。試験では、PRACS熱交換器の熱伝達率を求めるとともに、すべての系統が自然循環となる崩壊熱除去系の2次側ナトリウム系統、空気冷却器空気側の待機運転から起動時のスムーズな自然循環流量の立ち上がりを確認した。

Fully natural circulation system is adopted in a decay heat removal system (DHRS) of Japan Sodium Cooled Fast Reactor (JSFR). The JSFR has two loops of the main heat transport system in order to reduce number of components and the construction cost. The DHRS of JSFR consists of one DRACS and two PRACS, which have a heat exchanger in a primary-side inlet plenum of IHX in each loop. Sodium experiments were carried out for heat transfer characteristics of a sodium-sodium heat exchanger of PRACS and also start-up transient of the DHRS loop. Heat transfer coefficient on the tube outer surface was in good agreement with a conventional correlation under operation condition in the reactor. The transient experiments for the start-up of DHRS loop showed that smooth increase of natural draft in the air duct followed by the sodium flow rate in the DHRS loop. Some delay of the flow rate increase was recognized in the DHRS loop as compared with that of the natural draft in the air cooler.