Analyses of used BWR fuel assay data with the integrated burnup code system SWAT4.0. Issue 2 (1st February 2018)

• Record Type: Journal Article
• Authors: Tada, Kenichi; Kikuchi, Takeo; Sakino, Takao; Suyama, Kenya
• Is Part Of: Journal of nuclear science and technology. Volume 55:Issue 2(2018)
• Page Start: 138
• Page End: 150
• Publication Date: 2018-02-01
• Subjects: SWAT4.0 -- post-irradiation examination -- 2F2DN23 -- criticality safety -- burnup credit -- fuel debris -- Fukushima Daiichi nuclear power plant; Nuclear engineering -- Periodicals; Nuclear physics -- Periodicals; Nuclear energy -- Periodicals; 621.4805
• DOI: 10.1080/00223131.2017.1384705
• Languages: English
• ISSNs: 0022-3131

Abstract

ABSTRACT: Criticality safety of the fuel debris from the Fukushima Daiichi Nuclear Power Plant is one of the most important issues, and the adoption of burnup credit is desired for criticality safety evaluation. To adopt the burnup credit, validation of the burnup calculation codes is required. Assay data of the used nuclear fuel irradiated by the Fukushima Daini Nuclear Power Plant Unit 2 are evaluated to validate the SWAT4.0 code for solving the BWR fuel burnup problem. The calculation results revealed that the number densities of many heavy nuclides and fission products show good agreement with the experimental data, except for those of 237 Np, 238 Pu, and samarium isotopes. These differences were considered to originate from inappropriate assumption of void fraction. Our results implied overestimation of the (n, γ) cross-section of 237 Np in JENDL-4.0. The Calculation/Experiment – 1 (C/E–1) value did not depend on the type of fuel rod (UO2 or UO2 –Gd2 O3 ), which was similar to the case of PWR fuel. The differences in the number densities of 235 U, 239 Pu, 240 Pu, 241 Pu, 149 Sm, and 151 Sm have a large impact on k eff . However, the reactivity uncertainty related to the burnup analysis was less than 3%. These results indicate that SWAT4.0 appropriately analyzes the isotopic composition of BWR fuel, and it has sufficient accuracy to be adopted in the burnup credit evaluation of fuel debris.