Development of low-activation design method for reduction of radioactive waste (2). Precise neutron flux and activation estimation of nuclear power plants using MATXSLIB-J33T10

We have been developing low-activation concrete for biological shielding wall of nuclear power plants, for the purpose of reducing large amount of radioactive waste. Based on measurement of Eu and Co content in various aggregate candidates, limestone and electro-fused alumina were selected as the most feasible aggregate for low activation concrete. Induced activity in shielding wall was calculated for both low activation concrete and ordinary concrete using neutron flux obtained from DORT two-dimensional calculation made for typical ABWR and APWR models. We have prepared new cross section library named 'MATXSLIB-J33T10 that has multi-group structure in thermal energy. The library was processed from evaluated cross section library JENDL 3.3 by using NJOY 99.83. Activation cross section library for ORIGEN-79 code is prepared for each activation calculation case by collapsing JENDL-3.3 originated 183-group constants into 3-group activation cross section using 183-group neutron flux. One-group activation cross section was also prepared in the same manner for ORIGEN2 calculation. The ΣD/C value results for low-activation concrete was sufficiently low comparing to the ordinary concrete. By using the developed low-activation concrete, activation level of biological shielding wall concrete will be effectively decreased. The use of the developed low-activation concrete will contribute to economization of nuclear power plants decommissioning by reducing large amount of radioactive concrete waste. (author)