Preliminary hydraulic analysis, performed by Entergy, indicated that the highest containment
sump water temperature for a small break
LOCA was about 195 degrees Fahrenheit (EF). Entergy received an initial evaluation for minimum flow from the pump vendor (
Flowserve) in a letter dated November 9, 2007, which stated, in part, that while 900 gpm is recommended for continuous operation, 200 gpm is acceptable for up to a three hour duration in any
24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period. In addition,
Flowserve stated that if the suction water temperature was less than or equal to 200EF, and the temperature rise in the pump did not result in flashing, then extended operation would only result in shortened pump life (i.e., not a short term pump failure). Based on the preliminary information, Entergy concluded that the pumps will operate satisfactorily under all design basis accident conditions. The team evaluated Entergys immediate corrective actions, including
EOP changes, and Entergys
operability assessment and found these actions and assessments to be reasonable. Entergy is evaluating recirculation system hydraulic models and small break
LOCA accident scenarios to determine expected minimum reactor core flows and individual pump flows. In addition, Entergy is evaluating recirculation pump design characteristics to determine pump minimum flow requirements. The acceptability of Entergy's final determination of pump minimum flow requirements will be an unresolved item (
URI), pending further NRC review.
