Characterization of Pressure Tube Waste for OPG's L&ILW DGR

Abstract

Detailed characterization information on pressure tube waste is required in support of safety assessment and design of Ontario Power Generation (OPG)’s proposed Deep Geologic Repository (DGR) for Low and Intermediate Level Waste (L&ILW). This paper presents an overview of the physical, chemical and radiological characteristics of CANDU pressure tube wastes based on a comprehensive review of the available literature and the results of OPG pressure tube waste characterization activities conducted at Kinectrics. The physical, chemical and radiochemical characteristics of the base metal, indigenous oxide layer and deposits formed on the pressure tube as a result of exposure to coolant during service were examined. Radiochemical data is presented for key long-lived radionuclides, including H-3, C-14, Cl-36, Co-60, Zr-93, Nb-94, Cs-137 and actinides. Data for selected radionuclides were compared with predictions based on ‘first principles’ models which consider neutron capture reactions, radioactive decay, fission and deposition from coolant, where appropriate. In general, agreement between measured data and model predictions for these radionuclides was reasonable.