Reliability Proving Test on Maximum Thermal Loading of PWR Fuel Assembly

The thermal-hydraulic design technique of Japanese PWR fuel assembly was originally transferred from foreign PWR venders. Since then, the design of the fuel assembly has been improved and modified based on a large amount of operational experiences in Japan. The proving test program on Japanese PWR fuel assemblies was conducted at the Takasago Engineering Laboratory of the Nuclear Power Engineering Corporation (NUPEC). As part of this program, DNB (Departure from Nucleate Boiling) tests was performed with full length partial fuel assemblies simulating the 17×17 type PWR fuel assembly. The tests included steady state DNB tests and transient DNB tests. The test data were evaluated with several subchannel analysis codes and DNB correlations, and confirmed the reliability of the codes and the correlations. Many valuable results have been obtained through the present DNB test program on the PWR fuel assembly which is the first attempt carried out systematically in Japan. It is expected that the results will contribute to the improvesent of the design of PWR fuel assembly in the future.