Conceptual core design of passively safe small reactor for distributed energy system, PSRD-100

The Japan Atomic Energy Research Institute has been conducting a conceptual design of a passively safe small reactor for distributed energy system, PSRD-100. The PSRD-100 is an integral type light water reactor with a thermal output of 100 MW aimed at use of supplying district heat, electricity to small grids, and so on. The PSRD-100 has been designed on the basis of a basic design of the advanced marine reactor MRX and it adopts the natural circulation core cooling and the self-pressurization pressure control in the primary system. To simplify the system, the PSRD-100 is designed to operate without the volume control system and the purification system for a long time operation. From the neutronic and reactor physics analyses of the core, a long life time core operation of about 10 years without refueling or fuel shuffling was confirmed on the condition of using the low enrichment using the low enriched UO₂ fuel rods and the reactor load factor of 50 %, after parameter surveying on pin pitch, fuel enrichment, fuel rod arrangement in assembly, etc. The reactor physics analyses also indicated that the reactor control systems have enough safety margins for the state of clod shutdown of the reactor, although that is the most severe condition for the safety analyses for the PSRD-100 core. (author)