Technology readiness levels for partitioning and transmutation of minor actinides in Japan

In order to provide an assessment of the maturity of partitioning and transmutation (P and T) technology relative to its full-scale deployment, a technology readiness levels (TRL) approach was used. The definitions of TRL used in this study were based on those used in the Global Nuclear Energy Partnership (GNEP). The TRL was evaluated and the technology pathway was discussed for the systems of FBR and ADS for minor actinide (MA) transmutation, MA partitioning processes and MA-bearing fuels. The TRL for these systems/processes in Japan was found to be around TRL 3 to TRL 4. Through the evaluation, it was recognised that one of key issues was how nuclear calculation methodology for a MA-bearing core would be validated towards TRL 5. Several percentages of MA influence the core characteristics, which is important in licensing for FBR and ADS. On the other hand, a critical experiment with several kg of MA would be effective, but difficult at the existing experimental facility and would require a new one. It was also recognised that unit operations tests at engineering scale with actual spent fuel for a MA partitioning process would be difficult requirements to be satisfied at TRL 5 just after those with simulated spent fuel. For MA-bearing fuel development, engineering-scale fabrication and irradiation tests with actual separated materials were difficult requirements to be satisfied at TRL 5. The introduction of laboratory-scale tests with actual spent fuel for a MA partitioning process and with actual separated materials for MA-bearing fuel fabrication and irradiation before the engineering-scale tests (TRL 5) is an effective and efficient solution. (authors)