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At 1756 CDT with the plant operating at 10 … At 1756 CDT with the plant operating at 100% power, a reactor scram occurred in response to a reactor water level 3 signal from an apparent loss of feedwater. Both feedwater injection lines isolated when isolation valves were inadvertently closed, The cause of the isolation valve closure is under investigation.</br>When reactor water level lowered to level 2, high pressure core spray (HPCS) initiated automatically and recovered water level. The reactor core isolation cooling system (RCIC) was tagged out for maintenance at the time of the event.</br>Following the scram, main steam isolation valves isolated on low main steam header pressure. As a result, reactor pressure control was being controlled with the safety relief valves. SRV pressure control in turn led to EOP entry conditions on containment pressure and suppression pool level.</br>Both feedwater lines were opened, and normal reactor level control was restored. The MSIV's were opened and pressure control was returned to the turbine bypass valves and the main condenser.</br>Initial indications are that all plant equipment functioned as designed with the exception of the 'B' feed pump which experienced an apparent seal failure. The plant is stable in Mode 3. All plant conditions are understood.</br>This event is being reported in accordance with 10CRF50.72(b)(2) as an RPS actuation and an injection of HPCS into the reactor vessel, and in accordance with 10CRF50.72(b)(3) as a loss of safety function of HPCS, as it was manually disabled during recovery from the event. The HPCS Injection valve was manually overridden closed for 76 minutes. In addition,' containment isolation valves in multiple systems actuated in response to the RPV level 2 signal.</br>Reactor vessel water level lowered to below level 2. Decay heat is being removed by normal feedwater to the reactor vessel steaming to the main condenser. Offsite power is available and stable. Emergency Diesel Generators are available. </br>The licensee notified the NRC Resident Inspector.</br>* * * UPDATE FROM LICENSEE (D. WILLIAMSON) TO M. RIPLEY 1740 EDT ON 10/20/06 * * *</br>The closure signal to the main feedwater header isolation valves occurred when part of a chart recorder above the isolation valve control switches was dropped by an operator. The operator was attempting to adjust the paper drive mechanism in the recorder, and accidentally dropped the paper cartridge, which struck the 'CLOSE' pushbuttons on the isolation valve control switches.</br>Following the scram, there was a delay in placing the reactor mode switch in the 'SHUTDOWN' position, which is an immediate action required by procedure. Placing the mode switch to 'SHUTDOWN' bypasses the reactor low steam pressure MSIV Isolation. Reactor steam pressure began dropping after the scram, until it reached the MSIV automatic closure setpoint, and the MSIVs isolated,</br>In addition the licensee corrected one of the 10 CFR Section entries from "50.72(b)(3)(v)(A) POT UNABLE TO SAFE SD" to "50.72(b)(3)(v)(D) ACCIDENT MITIGATION." The licensee notified the NRC Resident Inspector.</br>Notified R4 DO (D. Powers) and NRR EO (N. Chokshi) R4 DO (D. Powers) and NRR EO (N. Chokshi)
22:56:00, 19 October 2006 +
42,921 +
22:35:00, 19 October 2006 +
22:56:00, 19 October 2006 +
At 1756 CDT with the plant operating at 10 … At 1756 CDT with the plant operating at 100% power, a reactor scram occurred in response to a reactor water level 3 signal from an apparent loss of feedwater. Both feedwater injection lines isolated when isolation valves were inadvertently closed, The cause of the isolation valve closure is under investigation.</br>When reactor water level lowered to level 2, high pressure core spray (HPCS) initiated automatically and recovered water level. The reactor core isolation cooling system (RCIC) was tagged out for maintenance at the time of the event.</br>Following the scram, main steam isolation valves isolated on low main steam header pressure. As a result, reactor pressure control was being controlled with the safety relief valves. SRV pressure control in turn led to EOP entry conditions on containment pressure and suppression pool level.</br>Both feedwater lines were opened, and normal reactor level control was restored. The MSIV's were opened and pressure control was returned to the turbine bypass valves and the main condenser.</br>Initial indications are that all plant equipment functioned as designed with the exception of the 'B' feed pump which experienced an apparent seal failure. The plant is stable in Mode 3. All plant conditions are understood.</br>This event is being reported in accordance with 10CRF50.72(b)(2) as an RPS actuation and an injection of HPCS into the reactor vessel, and in accordance with 10CRF50.72(b)(3) as a loss of safety function of HPCS, as it was manually disabled during recovery from the event. The HPCS Injection valve was manually overridden closed for 76 minutes. In addition,' containment isolation valves in multiple systems actuated in response to the RPV level 2 signal.</br>Reactor vessel water level lowered to below level 2. Decay heat is being removed by normal feedwater to the reactor vessel steaming to the main condenser. Offsite power is available and stable. Emergency Diesel Generators are available. </br>The licensee notified the NRC Resident Inspector.</br>* * * UPDATE FROM LICENSEE (D. WILLIAMSON) TO M. RIPLEY 1740 EDT ON 10/20/06 * * *</br>The closure signal to the main feedwater header isolation valves occurred when part of a chart recorder above the isolation valve control switches was dropped by an operator. The operator was attempting to adjust the paper drive mechanism in the recorder, and accidentally dropped the paper cartridge, which struck the 'CLOSE' pushbuttons on the isolation valve control switches.</br>Following the scram, there was a delay in placing the reactor mode switch in the 'SHUTDOWN' position, which is an immediate action required by procedure. Placing the mode switch to 'SHUTDOWN' bypasses the reactor low steam pressure MSIV Isolation. Reactor steam pressure began dropping after the scram, until it reached the MSIV automatic closure setpoint, and the MSIVs isolated,</br>In addition the licensee corrected one of the 10 CFR Section entries from "50.72(b)(3)(v)(A) POT UNABLE TO SAFE SD" to "50.72(b)(3)(v)(D) ACCIDENT MITIGATION." The licensee notified the NRC Resident Inspector.</br>Notified R4 DO (D. Powers) and NRR EO (N. Chokshi) R4 DO (D. Powers) and NRR EO (N. Chokshi)
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