Evaluation of the reactor safety analysis code system and improvement of the reliability and mainteinability of core structural equipments for 'Fugen'

The advanced thermal reactor ''Fugen'' is a heavy water-moderated, boiling light water-cooled, pressure tube type reactor developed independently in Japan, and is a thermal neutron reactor which burns plutonium on full scale for the first time in the world. In this paper, the software systems developed by the research entrusted by the Power Reactor and Nuclear Fuel Development Corp. and independently by Hitachi Ltd., such as those for the core design, safety design, the analysis of plant dynamic characteristics and core control plan for Fugen, and the proof and evaluation of them by the start-up test and others are described. Also the functions and features of an on-line process computer having prediction function, which was developed to realize the safe and efficient operation of Fugen, are explained, and the research and development of the maintenance and repair equipments for the construction peculiar to the pressure tube type reactor are reported. The advanced thermal reactor ''Fugen'' attained the rate of utilization of 72.4% for one year since April, 1979. The first periodic inspection was finished as scheduled, and the operation has been continued satisfactorily. Stress relief annealing was applied to all pressure tubes, and the pressure tube-monitoring device was developed. (Kako, I.)