In reactor performance of advanced fuel, 16ACE7TM, for Kori 2 nuclear power plant

An advanced nuclear fuel, 16ACE7TM, for 16x16 Westinghouse type plant is being verified in the Kori 2 plant, Korea. This fuel developed with the Westinghouse in USA and the INB in Brazil jointly has the following several outstanding benefits in comparison of the existing fuel: Batch average burnup of 55 GWD/MTU, 10% overpower margin increase, Neutron economy, failure free induced by debris or grid fretting, Prevention of incomplete control rod insertion, Integral top nozzle to solve spring screw failure. Out of pile performances had been verified through the extensive test program during the development period. After manufacturing four lead test assemblies (LTAs), in reactor performances are being verified successfully. This paper describes the inreactor performances of the advanced fuel resulted in the batch implementation starting from the middle of 2008. While the fuel is being irradiated, the coolant activity for the fuel integrity and the power history of LTAs for the design prediction of the power distribution were measured and evaluated periodically. During the refueling outage period after each cycle, the poolside examinations (PSEs) have been performed. Burnup dependent parameters, which are irradiation induced growth of fuel assembly length, fuel rod length and grid width, fuel assembly and fuel rod bow, fuel assembly twist, and fuel rod diameter decrease and fuel cladding oxide thickness, were measured and evaluated to confirm if they were within their design limits and if they have enough margins for next cycle. The parameters were measured using four examination devices: A device for dimensional measurement, an LVDT device for the rod diameter measurement, another LVDT device for the grid width measurement, and an ECT device for the cladding oxide thickness measurement. All parameters on the LTAs were within their expected values after two cycle irradiation and were evaluated to be within their expected design limits after three cycle irradiation. The assembly length, fuel rod length and grid width for the LTAs after 2 cycle irradiation have the design margins of around 45 %, 84% and 73%, respectively. And also the fuel has been evaluated to have a sufficient margin from the cladding oxide thickness design point of view. The other burnup dependent parameters such as fuel assembly bow, assembly twist, rod bow and rod diameter have evaluated not to have an effect on the fuel integrity. After the successful irradiation during 2 cycles, this fuel is being prepared for the commercial supply to the operating nuclear power plant in Kori site. These LTAs after 3 cycle irradiation will be verified through the following programs, such as the PSEs for assembly and rod, hot cell examinations for rod and skeleton. These campaigns are scheduled to be started from the middle of 2008. The 16ACE7TMeven after the commercial supply will be verified continuously through the surveillance program