Kinetic Parameter βeff/ℓ Measurement on Low Enriched Uranyl Nitrate Solution with Single Unit Cores (600𝛗;, 280T, 800𝛗;)of STACY

Abstract

The kinetic parameter βeff/ℓ of low enriched (10% EU) uranyl nitrate solution was measured by the pulsed neutron source (PNS) method in STACY This measurement was repeated systematically over several uranium concentrations from about 195 gU/l to about 430 gU/l. Used core tanks were two cylindrical tanks whose diameters are 600 mm and 800 mm and one slab tank which has 280 mm thickness and 700 mm width. In this report, experimental data such as solution conditions, critical solution level for each solution condition, subcritical solution levels where measurements were conducted, measured decay time constants of prompt neutron and extrapolated βeff/ℓ values are described as well as basic principle of the PNS method. The kinetic parameter βeff/ℓ values were evaluated also by computation with the diffusion code CITATION in SRAC and the nuclear data library JENDL 3.2. Strong linear correlation has been found between kinetic parameter βeff/ℓ and uranium concentration regardless of differences of reflecting conditions or core tank conditions. Experimentally or computationally evaluated βeff/ℓ value is about 90 s-1 at 195 gU/l and about 170 s-1 at 430 gU/l and both experimental and computational values show good agreement within an error of 3% which is comparable to about 2% uncertainty of measurement.