Measurement and analysis of reactivity worth of Am sample in water-moderated low-enriched UO fuel lattices at TCA

TCAに構築した軽水減速低濃縮ウラン燃料炉心におけるAmサンプル反応度価値の測定と解析

櫻井 健 ; 森 貴正; 須崎 武則*; 岡嶋 成晃  ; 安藤 良平*; 山本 徹*; Liem, P. H.*

Sakurai, Takeshi; Mori, Takamasa; Suzaki, Takenori*; Okajima, Shigeaki; Ando, Yoshihira*; Yamamoto, Toru*; Liem, P. H.*

The reactivity worths of 22.82 grams of Am oxide sample were measured and theoretically analyzed in water-moderated UO fuel lattices in seven cores of the Tank Type Critical Assembly (TCA) at the Japan Atomic Energy Agency for an integral test of Am nuclear data. These cores provided a systematic variation in the neutron spectrum between the thermal and resonance energy regions. The sample reactivity worth was measured with uncertainty of 2.1% or less. The theoretical analysis was performed using the JENDL-3.3 nuclear data with a Monte Carlo calculation method. Ratios of calculation to experiment(C/E's) of the reactivity worth were between 0.91 and 0.97, and showed no apparent dependence on the neutron spectrum. In addition, sensitivity analysis based on the deterministic calculation method was carried out to obtain the impact of changing the Am capture cross-section on the sample reactivity worth. The result of this analysis showed that the C/E could be significantly improved by almost uniformly increasing the Am capture cross-section of JENDL-3.3 by 25 30%.