One-Third-Scale Air--Water Pump Program, LOCA and pump overspeed analyses. Final report

A pump model developed from air--water test data (the B and W air--water pump model) was incorporated into the CRAFT2 computer code, which is used to solve the evolution of system hydrodynamics and core power generation during the blowdown phase of a hypothetical loss-of-coolant accident. Peak cladding temperature calculations were performed for several break sizes and configurations using this pump model. The results of these calculations were compared to previously calculated results for B and W's 205-fuel assembly plants obtained using the same CRAFT model but one that used a pump model developed from the Semiscale data. The newly calculated peak cladding temperatures were essentially the same as those obtained previously. Pump overspeed calculations were also performed for B and W's 205-fuel assembly plants using the B and W air--water pump model. The use of a realistic discharge coefficient of 0.6 resulted in a peak speed of 3007 rpm, 253% of rated speed, for an 8.55-ft2 double-ended break in the pump discharge piping. This result agrees reasonably well with the overspeed calculation performed in 1973 for B and W's 177-fuel assembly plants, which did not include pump head or torque degradation as a function of void fraction. Therefore, it appears that overspeed calculations are basically unaffected by the use of the B and W air--water pump model