Evaluation of isotopic compositions in LWR spent fuel

The purpose of this work is to evaluate the availability of computer codes and nuclear data libraries for estimating isotopic compositions in spent nuclear fuel. The abstract of the computer code COMRAD and the nuclear data library JDDL is presented which have been developed to calculate the isotopic compositions in spent fuel. The sphere of the accuracy of the computed results is evaluated by analyzing isotopic compositions of LWR spent fuel with computer codes COMRAD, ORIGEN-1 and -2. The computed results on 106Ru and 154Eu contents in spent fuel show much differences from measured ones, and show different values on 85Kr and 129I according to the computer code used. The COMRAD code with JDDL is also applied to analyzing isotopic compositions in spent fuel reprocessing plants. Using the computed results, simple fitting formulas are introduced to estimate isotopic compositions of actinide group and compared with measured values of some reprocessing plants. This work was performed by the Working Group on Evaluation for Generation and Depletion of Nuclide of JNDC. (author)