Development of the residual sodium quantification method for a fuel pin bundle of SFRs before and after dry cleaning

• Published in: Journal of nuclear science and technology Vol. 57; no. 4; pp. 408 - 420
• Main Authors: Kudoh, Hideyuki, Ohtani, Yuichi, Hara, Masahide, Katoh, Atsushi, Ohtaka, Masahiko, Ide, Akihiro
• Format: Journal Article
• Language: English
• Published: Tokyo Taylor & Francis 02-04-2020; Taylor & Francis Ltd
• Subjects: Argon; Blowing time; Bundling; Dry cleaning; fuel handling system; Nuclear fuels; Sodium; Sodium cooled reactors; sodium test loop; Sodium-cooled fast reactor
• ISSN: 0022-3131; 1881-1248
• DOI: 10.1080/00223131.2019.1691069

In a fuel handling system of 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). A next-generation SFR in Japan has adopted an advanced dry-cleaning system that consists of argon gas blowing to remove the metallic residual sodium on the FA, which increases economic competitiveness and reduces waste products thanks to a waterless process. In this R&D work, the performance of the dry cleaning process has been investigated.
This paper describes experimental and analytical studies focusing on the amount of residual sodium remaining on a fuel pin bundle before and after the argon gas blowing process. The experiments were conducted using a sodium test loop and a short (approximately 1 m) specimen consisting of a 7-pin bundle. The effects of the blowing gas velocity and the blowing time were quantitatively analyzed in the experiments. The blowing gas velocity was varied from 3.9 to 31.3 m/s, and 113 data-points of the residual sodium were collected during the experiment. On the basis of these experimental results, the residual sodium quantification method for the fuel pin bundle was constructed.