Estimation of the Radionuclide Inventory of Activated Decommissioning Waste from Ontario Power Generation's Darlington Nuclear Generating Station

Abstract

This paper presents the results of a detailed assessment of the neutron activated radionuclide inventory in decommissioning waste from Darlington. A PC-based code was used to estimate the radionuclide concentrations in activated reactor core components. For each component, the inputs included a) power history, b) material composition data, c) applicable value of neutron flux d) a thermal flux correction factor, e) component mass and f) temperature. Various OPG documents were examined to assemble the required data inputs. The overall activity, 33 years after shutdown, for each Darlington unit was estimated to be 4.2E+16 Bq. Ni-63 accounts for approximately 95 % of this activity. Other key radionuclides are Co-60, Ni-59, Nb-94, C-14, Fe-55, Zr-93, Mo-93 and Cl-36. The end shields are the dominant source for C-14, Fe-55, Co-60, Ni-59, Ni-63 and Cl-36 activities. The pressure tubes and the calandria tubes are the principal sources for Zr-93. Nb-94 is associated exclusively with pressure tubes. Estimated radionuclide activities were generally consistent with previous estimates for Pickering-A and Bruce-A stations.