RELIABILITY PROVING TEST ON MAXIMUM THERM AL LOADING OF PWR FUEL ASSEMBLY

The thermal-hydraulic design technique of Japanese PWR fuel assembly w as originally transferred from foreign PWR venders. Since then, the de sign of the fuel assembly has been improved and modified based on a la rge amount of operational experiences in Japan. The proving test progr am on Japanese PWR fuel assemblies was conducted at the Takasago Engin eering Laboratory of the Nuclear Power Engineering Corporation(NUPEC). As part of this program, DNB(Departure from Nucleate Boiling) tests w as performed with full length partial fuel assemblies simulating the 1 7x17 type PWR fuel assembly. The tests included steady state DNB tests and transient DNB tests. The test data were evaluated with several su bchannel analysis codes and DNB correlations, and confirmed the reliab ility of the codes and the correlations. Many valuable results have be en obtained through the present DNB test program on the PWR fuel assem bly which is the first attempt carried out systematically in Japan. It is expected that the results will contribute to the improvesent of th e design of PWR fuel assembly in the future.