Review of Safety Criteria for High Burn-up Fuel and Evaluation of Fuel Performance

The problems on the high burn-up fuel are mostly related with the integrity of fuel cladding material. The high burn-up problems which have not experienced yet are important issues not only in Korea but also in other developed nuclear countries. Since the nuclear fuel cladding needs a lot of R and D funds to handle its radioactive material and get the experiment data, most of the nuclear countries are cooperating with the other countries or organizations as a type of international R and D program such as CABRI, SCIP, and HALDEN program. In our standpoint, the international R and D program is a good opportunity to get a lot of the results from that kind of programs, even by the small fund. The nuclear fuel cladding is consisted of Zirconium alloy, and in domestic commercial reactors, the Korea Nuclear Fuel Company has used the ZIRLO alloy as the fuel cladding material from several years ago. The pending problems in integrity evaluation of cladding material can divide two items, and first problem is CRUD deposition during normal operation and the other issue is related with high burn-up. The CRUD deposition can be removed by ultra-sonic cleaning technology, and recently, KINS has approved that technology in its review process. Even though there are no important issues of fuel cladding material during current operation, the integrity evaluation of the high burn-up fuel cladding must be considered as a safety pending issue. In this study, the safety criteria to evaluating the high burn-up fuel cladding were reviewed and the states of the each safety criteria were analyzed. At the same time, the safety evaluation of commercial cladding was performed using verification code, FRAPCON, and the safety factors and R and D issues of cladding material will be presented for the high burn-up operation