Evaluation on Characteristics of Wastes from Pyro-processing of CANDU SNFs based on CANDU FS v5.1

To reuse valuable fissile materials in SNFs and reduce volume and toxicity of SNFs, KAERI has been developing P&T technology based on pyro-processing and SFR. In this technology, only PWR SNFs are considered because of low fissile content and high purity of plutonium of CANDU SNFs. Low fissile content reduces economic profit of pyro-processing of CANDU SNFs. And recovery of TRU containing high purity plutonium with lack of economic benefits could cause misunderstanding and declination of the credibility on non-proliferation. Characteristics of wastes and products from pyroprocessing of CANDU SNFs based on CANDU FSv5.1 are evaluated in this study. More than 99 % of decay heat, radioactivity, and radiotoxicity are generated from the Cs-Filter Waste, Sr Waste, U/TRU Ingot at disposal time. With complete reuse of U/TRU in SFR and longterm storage of the Cs-Filter Waste and the Sr Waste, heat load of repository could be considerably reduced. Characteristics of CANDU pyro-wastes identified in this study will be used to design disposal system for comparison of direct disposal scenario and closed fuel cycle scenario of CANDU SNFs. CANDU SNFs can be disposed of in fairly small area compared to PWR SNFs due to very low decay heat, radioactivity, and radiotoxicity of CANDU SNFs. Decay heat, radioactivity, radiotoxicity of CANDU SNFs is 1/7, 1/5, and 1/9 of PWR SNFs respectively at disposal time.