Possibility of a Pressurized Water Reactor Concept with Highly Inherent Heat Removal Following Capability.

If the core power inherently follows change in heat removal rate from the primary coolant system within small thermal expansion of the coolant which can be absorbed in a practical size of pressurizer, reactor systems may have more safety and load following capability. In order to know possibility and necessary conditions of a concept on reactor core and primary coolant system of a pressurized water reactor (PWR) with such "highly inherent heat removal following capability", transient analyses on an ordinary two-loop PWR have been performed for a transient due to 50% change in heat removal with the RETRAN-02 code. The posibility of a PWR concept with the highly inherent heat removal following capability has been demonstrated under the conditions of the absolute value of ratio of the coolant density reactivity coefficient to the Doppler reactivity coefficient more than 10 x 103 kg·cm3 which is two to three time? larger than that at beginning of cycle (BOC) in an ordinary PWR and realized by elimination of the chemical shlm, the 12% lower average linear heat generation rate Of 17.9 kW/m, and the 1.5 times larger pressurizer volume than those of the ordinary PWR.