COMPARISON OF CALCULATED VALUES WITH MEASURED VALUES ON THE AMOUNT OFTRU AND FP NUCLEIDES ACCUMULATED IN GADOLINIUM BEARING PWR SPENT FUELS

Destructive analyses for five spent fuel samples taken from a Gd beari ng fuel assembly were done. The measured amounts of actinides of U-234 -238, Np-237, Pu-238-242, Am-241,Am-242m,Am-243 and Cm-242,Cm-244, and fission products of Cs-134 and Eu-154 were used for evaluating the ac curacy of calculation made by CASMO-MICBURN and ORIGEN-2 codes. The ef fect of Gd on the neutron spectrum was taken into account in the CASMO -MICBURN calculation. The amounts of U-235, Pu-239 and Pu-241 calculat ed by CASMO-MICBURN agreed well with the observed values within about 3%. On the other hand, the amounts obtained from ORIGEN-2 calculation showed lower values than those observed, especially by -12% in average in U-235 for Gd2O3-UO2 fuel. The main cause of this large difference may be attributed to the effect of Gd on the neutron spectrum. The amo unts of the other actinides by both calculation codes revealed no sign ificant difference in nearly 10% except for Am-242m, in which a large fluctuation among the samples was observed. About 10% difference betwe en the measured values and the calculated values was also observed for Cs-134, but the calculated values for Eu-154 showed a significant dif ference from measured values.