Transient response of a 145-fuel-assembly advanced light water reactor

B W Nuclear Service Company (BWNS) is evaluating a 145-fuel-assembly, 1800-MW(thermal), nuclear steam system (NSS), which includes passive ancillary safety systems. The B W design features two loops, two recirculating steam generators, four cold legs with four canned rotor reactor coolant (RC) pumps, a 71-m{sup 3} pressurizer, and two core flood tanks. The 145-fuel-assembly (FA) design does not include high-pressure core makeup tanks. The transient response of the BWNS 145-FA advanced light water reactor (ALWR) was investigated by performing the following design bases performance and safety analyses: reactor trip from full power, loss of feedwater from full power, turbine trip from full power, control rod withdrawal from zero power, steam-line break from zero and full power, and loss of off-spite power from full power. In addition, sensitivity studies were performed in which the aforementioned transients were analyzed with a smaller pressurizer (37 to 22 m{sup 3} liquid), followed by re-analysis with an enlarged primary reactor coolant system (RCS) volume-120% of nominal volume - with the original pressurizer volume of 71 m{sup 3}. The sensitivity studies were included to determine if additional volume (i.e., pressurizer/system) yielded more transient-resistant results. The RELAP5/MOD2 computer code was used to assess the transient response ofmore » the 145-FA ALWR.« less