Operational Experiences of On-Site Transport of Spent Nuclear Fuels in Korea

Since 1990 more than 800 PWR spent nuclear fuel assemblies has been on-site transported using two kinds of transport casks from one unit to nearby another unit in order to secure the storage capacity of spent nuclear fuel of the Kori nuclear power plant in Korea. The complete on-site transport system, which includes two transport casks, the related equipment and two transport vehicles, had been provided. Considerable amount of modification to the existing power plant equipment and facilities had been carried out. Two kinds of the KSC-4 cask and the CASTOR KN-12 cask were developed and licensed in accordance with the Korea and the IAEA’s safe transport regulations. From 1990 to the first half of 2002 two KSC-4 casks were used and more than 420 spent nuclear fuels were transported. From the second half of 2002 two CASTOR KN-12 cask have been used to transport more than 400 spent nuclear fuels. About 180 spent nuclear fuels of Kori site are transported using the CASTOR KN-12 cask this year, and the KSC-4 casks are no longer used. The CASTOR KN-12 cask was designed to transport twelve spent nuclear fuel assemblies from pressure water reactors and to comply with the requirements of the Korea and the IAEA regulations for Type B(U)F package. PWR spent nuclear fuels with maximum initial enrichment of 5.0wt.%, maximum average burn-up of 50,000MWD/MTU and minimum cooling time of 7 years are loaded and subsequently transported under dry and wet conditions. The loaded weight of the cask with impact limiters is 85 tons. Two casks were fabricated in accordance with ASME B&PV code Section III Division 3. The related equipment to handle the cask and to perform on-site transport are cask lifting devices, cask lid handling tools, crane adapters, vacuum drying and helium back-filling equipment and cask cool-down equipment, spent nuclear fuel handling tool, decontamination equipment using high pressure water and transport vehicles. However, spent nuclear fuels of the Kori site has been transported under wet condition to save the whole transport cycle time, and then the related equipment for the wet transport condition has been used excluding vacuum drying and helium back-filling equipment and cask cool-down equipment. The Quality Assurance Program through the whole progress including design, fabrication and transport has been established and the strict Quality Control has been carried out. For each transport the transport inspection of the Korea regulatory body in accordance with the Korea Atomic Energy Act has been performed so as to achieve the required safety and reliability of the onsite transport of spent nuclear fuels. No accident of any kind has occurred up to the present and spent nuclear fuels of Kori site have been safely transported. This paper describes the transport system and the operational experiences for the on-site transport of spent nuclear fuels using the CASTOR KN-12 transport cask in Korea.