CRITICAL EXPERIMENTS ON 10-PERCENT ENRICHED URANYL-NITRATE SOLUTION USING A 60-CM-DIAMETER CYCLINDRICAL CORE

A series of critical experiments with 10% enriched uranyl nitrate solu tion using a cylindrical core tank 60 cm in diameter have been perform ed with the Static Experiment Critical Facility at the Nuclear Fuel Cy cle Safety Engineering Research Facility in the Tokai research establi shment of the Japan Atomic Energy Research Institute. In the first ser ies of experiments using the cylindrical core tank, systematic data of the critical height for water-reflected cores and unreflected cores w ere obtained by changing the uranium concentration of the fuel solutio n from 313 to 225 g U/l. As the reactivity of each core is controlled only by solution height, these criticality configurations, which have simple cylindrical shapes, are available for the validation of calcula tion codes used in criticality safety designs of nuclear fuel cycle fa cilities. The neutron multiplication factors of experimental cores wer e calculated with the two-dimensional transport code TWOTRAN in the SR AC code system and with the continuous-energy Monte Carlo code MCNP4A, employing the Japanese evaluated nuclear data library JENDL-3.2. The calculations from the combination of these calculation codes and the n uclear data library reproduce the neutron multiplication factors withi n an error of 0.9% for the experimental configuration of critical core s.