Development of the residual sodium quantification method for a fuel assembly of SFRs

ナトリウム冷却炉の燃料集合体の残留ナトリウム量評価手法の開発

工藤 秀行*; 犬塚 泰輔*; 原 正秀*; 加藤 篤志 ; 永井 桂一 ; 井手 章博*

Kudo, Hideyuki*; Inuzuka, Taisuke*; Hara, Masahide*; Kato, Atsushi; Nagai, Keiichi; Ide, Akihiro*

ナトリウム冷却炉の使用済み燃料の乾式洗浄試験の成果に基づいて、集合体に残留するナトリウム量の評価手法を構築した。

In sodium-cooled fast reactors (SFRs), it is necessary to remove the sodium remaining on spent fuel assemblies (FAs) before storing them in a spent fuel water pool (SFP) in order to minimize plant operating loads. A next-generation SFR in Japan has adopted an advanced dry cleaning process which consists of the following steps: argon gas blowing to remove the metallic residual sodium on the FA, moist argon gas blowing to deactivate the residual sodium, and direct storage in the SFP. This process increases economic competitiveness and reduces waste products. In this R&D work, performance of the dry cleaning process has been investigated. This paper describes experimental and analytical work focusing on the amount of residual sodium remaining on FA components, for instance the handling head, the wrapper tube, the upper shielding, and the entrance nozzle which was conducted after investigation of residual sodium on fuel pin bundles as a part of series study of the cleaning process.