Measurements of the modified conversion ratio by gamma-ray spectrometry of fuel rods for water-moderated UO[sub 2] cores

Journal Article · Tue Feb 01 04:00:00 EST 1994 · Nuclear Science and Engineering; (United States)

OSTI ID:5065841

Nakajima, Ken; Akai, Masanori; Suzaki, Takenori ^[1]

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1. Japan Atomic Energy Research Inst., Ibaraki (Japan). Dept. of Fuel Cycle Safety Research

The modified conversion ratio is defined as the ratio of [sup 238]U captures to total fission. Gamma-ray spectrometry of irradiated fuel rods has been introduced to measure this quantity in two types of water-moderated low-enriched UO[sub 2] cores: the standard core, called the 1.42S core, and a tight-lattice core, called the 0.56S core. The water moderator-to-fuel volume ratios V[sub m]/V[sub [line integral]] of the cores are 1.420 and 0.564, respectively. As no activation foil is used in this method, no corrections are needed for the neutron self-shielding and neutron flux depression that are caused by such a foil. Instead, the gamma-ray self-shielding effect due to the fuel rod must be corrected. The modified conversion ratios measured by this method are 0.457 for the 1.42S core and 0.724 for the 0.56S core. The errors in the experimental results are estimated to be [approximately]3%. Computer analyses using the VIM continuous-energy Monte Carlo code with the JENDL-2 library show that the calculated value is [approximately]6% larger than the experimental one for the tight-lattice 0.56S core.

• OSTI ID: 5065841
• Journal Information: Nuclear Science and Engineering; (United States), Journal Name: Nuclear Science and Engineering; (United States) Vol. 116:2; ISSN NSENAO; ISSN 0029-5639
• Country of Publication: United States
• Language: English

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