Measurements of the Modified Conversion Ratio by Gamma-Ray Spectrometry of Fuel Rods for Water-Moderated UO₂Cores

Determination of the 238U capture to total fission ratio in alternate depleted uranium/polyethylene shells with D-T neutrons

“…Since 143 Ce generated by 235 U fission or 238 U fission induced by neutrons at varied energies cannot be distinguished experimentally, it is common to calculate these ratios by simulation codes [3][4][5], which can provide realistic values of the ratios. In this paper, the ratios were calculated by the MCNP4B code employing the ENDF/B-VI library.…”

“…␥ rays were measured by an HPGe spectrometer consisting of an ORTEC GEM60P detector with a sensitive volume of 250 cm 3 and an ORTEC Gammavision analyzer. The system has an energy resolution of 1.87 keV and a relative efficiency of 60% at 1.33 MeV.…”

“…Nakajima et al [3,4] measured the ratios of water-moderated low-enriched UO 2 cores with various water moderator-to-fuel volume (V m /V f ) ratios, by gamma-ray spectrometry of irradiated fuel rods with an HPGe detector. Bergmann et al [5] measured the ratio of a boiling water reactor (BWR) by gamma spectroscopy of individual fuel rods.…”

Neutronics Analysis of Full MOX BWR Core Simulation Experiments FUBILA

“…A modified conversion ratio, which is defined as the ratio of a neutron capture rate of 238 U to a total fission rate in a fuel pellet, was measured by a specific gamma ray measurement method proposed by Nakajima et al 34) Reference 15) shows the obtained results.…”

“…The modified conversion ratios were measured by the technique developed by Nakajima et al 34) The neutron capture rate of 238 U during irradiation was determined by the measurement of the intensity of 277 keV gamma rays in the decay of 239 Np in an irradiated fuel rod, and the total fission rate by the measurement of the intensity of 293 keV gamma rays from the decay of 143 Ce. The measurement was applied to the axially middle part of fuel rods with the core radial locations (X, Y) = (28,26) and (29,28), which were the total Pu contents of 11.5 and 5.0 wt%, respectively, in the 40 and 70% void cores.…”