Am-241 sample reactivity experiments in TCA, 1; Measurement results and evaluation of uncertainty in calculation caused by nuclear data uncertainty

Sakurai, Takeshi; Mori, Takamasa; Suzaki, Takenori*; Okajima, Shigeaki  ; Ando, Yoshihira*; Yamamoto, Toru*

Measurement and analysis have been made for the reactivity worth of Am-241 oxide sample(23 g) in water-moderated low-enriched UO fuel lattices with water-to-fuel volume ratios ranging from 0.56 to 3.0 at TCA of JAEA to validate the capture cross section of Am-241 of thermal to resonance energy region in current nuclear data library. The reactivity worth of sample at the core center was measured with uncertainty of 0.4% 2.1%. The analysis was made by using the continuous energy Monte Carlo transport code MVP with JENDL-3.3 nuclear data. The reactivity worth was calculated from difference of effective multiplication factors and was obtained with statistical uncertainties of 0.6% 1.1%. The calculation underestimated the measurement by 4% 9%. Furthermore, an evaluation was made for the uncertainty in calculation caused by nuclear data uncertainty to investigate the present discrepancy between calculation and measurement.