Draft; Thermal-hydraulic evaluation of Joyo fuel subassembly with local blockage

「常陽」燃料集合体局所閉塞時の熱流動特性評価

大平 博昭; 高松 操 

Ohira, Hiroaki; Takamatsu, Misao

「常陽」のUCS下面とMARICO-2試料部との接触により発生した金属粉が燃料集合体のサブチャンネルを閉塞した場合の熱的影響を、非定常サブチャンネル解析コードASFREを用いて解析評価した。発生した金属粉の量を保守的に仮定したにもかかわらず、燃料,被覆管及び冷却材の各温度は、定格運転時,異常な過渡変化時及び事故時のいずれの場合にも、閉塞に起因して過度に上昇することはなく、炉心冷却性能が損われないことが明らかとなった。

In the incident of the experimental fast reactor Joyo on June 2007, little amount of metal powder was estimated to be produced by the contact between the bottom of the upper core structure and the test section of the material testing rig with temperature control. Up to now, no foreign materials were detected by the in-vessel observations. However, a small amount of metal powder which could be placed into the fuel pin bundles was assumed in the present study. Preliminary safety evaluation of the wire-wrapped fuel pin bundles of Joyo with local blockage were performed in the rated power operational condition, an anticipated transient during operation and an accident. A single-phase transient subchannel analysis code ASFRE, which was verified by various local blockage experiments in France and in Japan, was applied to the present evaluations. From these results, it was concluded a small amount of metal powder assumed to be produced by the incident would not affect to the safety operations in rated power conditions, in anticipated transients and in accidents.