Improvement of evaluation of irradiation test condition in JOYO

not registered ; Kitamura, Ryoichi; Aoyama, Takafumi 

In order to improve the calculation accuracy of the irradiation test conditions in the experimental fast reactor JOYO, a three dimensional, continuous energy Monte Carlo code "MCNP" was employed. The fission product yields (148Nd) in the instrumented test assembly (INTA-2) which was loaded between the driver fuel subassemblies and reflectors were evaluated in this study. The results from the "MCNP" code were compared with the experimental values. In the calculation of the "MCNP" code, the neutron source distribution data which was calculated with the JOYO core management code system "MAGI" was used to evaluate the neutron flux and spectrum inside the INTA-2 subassembly. The Nd yields were evaluated with the calculated fission reactions and the fission yield data from JNDC-V2. The calculated Nd yields werc compared with the experimental values which were obtained from post irradiation examination results. The ratios of the "MCNP" values to experimental values of Nd yields are about 0.991.00 of all pins. The "MCNP" code calculation values were within the range of the experimental error. These results indicate that the irradiation condition of the subassembly which was loaded next to the reflector can be evaluated accurately with the "MCNP" code.