Nuclear Analysis of PIE Data of Irradiated BWR 8×8-2 and 8×8-4 UO2 Fuel Assemblies

Abstract

The measured pellet average inventories of actinides and fission product nuclides on the fifteen samples taken from a three-cycle irradiation BWR 8Â8-2 UO 2 assembly were compared with those of assembly burnup calculations using a collision probability method (SRAC) with the JENDL-3.2 nuclear data library. The present calculations overestimate the inventories of 235 U, well reproduce those of 239 Pu and 240 Pu, yet underestimate those of 236 U, 237 Nd, 238 Pu, 241 Pu, and 242 Pu. The inventories of minor actinides are underestimated by the present analysis except for 241 Am. The major FP nuclides contributing to neutron absorption such as Nd, Cs, Eu, and Sm are almost well reproduced by the present calculations. The measured pellet average burnups and major actinide inventories on the twenty samples taken from four BWR 8Â8-4 UO 2 assemblies were also compared with those of the burnup calculations using SRAC and a continuous energy Monte Carlo burnup analysis code (MVP-BURN). Most of the calculated pellet average burnups of both codes agree with the measurements within the range of AE10%. The general trends of the measured pellet radial distributions of actinide and FP nuclides on six samples of the 8Â8-4 UO 2 assemblies were well reproduced by the burnup calculations of MVP-BURN.

SCALE 5 Analysis of BWR Spent Nuclear Fuel Isotopic Compositions Safety Studies

“…Similar underpredictions and overpredictions of the mentioned isotopes were also observed in other benchmark studies. 19 The large discrepancies between the measured and the calculated concentrations could be to the result of the suspected uncertainties in the nuclear data or more systematic errors like solubility of isotopes in the measured solution as in case of Cm isotopes were omitted in comparisons because no measurement data were available for most of the samples.…”

“…24. SF98-1, SF98-2, SF99-1, and SF99-10 samples were not modeled because these samples were taken either from the natural blanket region (from 0 to about 155 mm) 19 or very close to the blanket region at the bottom and top of the two fuel rods. Because of the large flux gradient in that region, a 2-D model is not valid and a detailed three-dimensional assembly model would be required to capture the different spectral effects.…”

“…Most of the reactor operation data and the assembly/fuel rod design parameters were obtained from Nakahara et al 10 based on the related JAERI report 8 for the Fukushima Daini-2 measurements. As the measured Fukushima fuel assembly 2F2DN23 is classified as an 8 × 8-2 lattice type, 19 the channel and water rod data were obtained from the reported Tsuruga 8 × 8-2 lattice dimensions in a recent Japan Nuclear Energy Safety Organization report on BWR isotopics measurement. Rod SF98 corresponds to position B-2 within the assembly.…”

Radioactivity of fission product and heavy nuclides deposited on soil in Fukushima Dai-Ichi Nuclear Power Plant accident

“…The correlations of the radioactivity ratios of Cs and Pu isotopes to fuel burnup were obtained from the available burnup calculation results [3] for the Cs and Pu isotopes, and from the experimental data [3,9] for the Pu isotopes. The referred calculation results were those for a lead use 9 6 9-9 fuel assembly which was loaded in the unit 1 of Fukushima Dai-Ni Nuclear Power Station (2F-1) and irradiated up to five cycles.…”

“…In addition to the calculation-based correlations, the experiment-based correlation was also compiled from the measured isotopic inventories of Pu isotopes for BWR fuels [3,9]. Figure 10 shows the obtained correlation.…”