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On February 6, 2001, at approximately 2150 … On February 6, 2001, at approximately 2150, the Point Beach Nuclear Plant (PBNP) Unit 2 tripped from 100% power. The trip was the result of a turbine generator lockout apparently caused by one of the generator stator neutral ground fault detection devices (27/59N relay). System and components required to perform following the reactor trip operated as designed with the possible exception of the cross over steam dump system. This system actuated as expected to minimize the turbine over speed; however, main condenser vacuum was lost when the dump valves apparently failed to reseat promptly. The reactor coolant system was maintained in hot standby following the trip with temperature maintained via the steam generator atmospheric steam dump valves.</br></br>Following extensive trouble shooting and a thorough incident investigation, PBNP Unit 2 was restarted on February 8th. Since the exact cause for the actuation of the 27/59N relay could not be determined, the plant was returned to operation after completing a temporary modification to change the relay circuit from a generator lock out actuation to a common alarm function. Prior to 1987, the PBNP units had operated without these relays. Other installed protective relaying is available to minimize the risk of faulting due to a stator ground.</br></br>The NRC was notified of this event via the ENS at 2244 on February 6, 2001. The safety and welfare of the public and the plant staff was not impacted by this event.</br></br>FACILITY NAME (1) PAGE (3) LER NUMBER (6) DOCKET NUMBER (2) Point Beach Nuclear Plant Unit 2 05000301 Point Beach Nuclear Plant Unit 2 05000301 +
On February 6, 2001, at approximately 2150 … On February 6, 2001, at approximately 2150, the Point Beach Nuclear Plant (PBNP) Unit 2 tripped from 100% power. The trip was the result of a turbine generator lockout apparently caused by one of the generator stator neutral ground fault detection devices (27/59N relay). System and components required to perform following the reactor trip operated as designed with the possible exception of the cross over steam dump system. This system actuated as expected to minimize the turbine over speed; however, main condenser vacuum was lost when the dump valves apparently failed to reseat promptly. The reactor coolant system was maintained in hot standby following the trip with temperature maintained via the steam generator atmospheric steam dump valves.</br></br>Following extensive trouble shooting and a thorough incident investigation, PBNP Unit 2 was restarted on February 8th. Since the exact cause for the actuation of the 27/59N relay could not be determined, the plant was returned to operation after completing a temporary modification to change the relay circuit from a generator lock out actuation to a common alarm function. Prior to 1987, the PBNP units had operated without these relays. Other installed protective relaying is available to minimize the risk of faulting due to a stator ground.</br></br>The NRC was notified of this event via the ENS at 2244 on February 6, 2001. The safety and welfare of the public and the plant staff was not impacted by this event.</br></br>FACILITY NAME (1) PAGE (3) LER NUMBER (6) DOCKET NUMBER (2) Point Beach Nuclear Plant Unit 2 05000301 Point Beach Nuclear Plant Unit 2 05000301 +
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