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On August 23, 2006, at 1035 hours, the Rea … On August 23, 2006, at 1035 hours, the Reactor Protection System was manually actuated while at reduced load of approximately 68 percent reactor power upon indication of an apparent disparity in net electric load. It was determined that the cyclic operation of the condenser steam dumps varied steam to the turbine resulting in the indicated drop in electrical output power from about 500 Mwe to 150 Mwe. The manual trip is reportable under 10 CFR 50.72(b)(2)(iv). The event started when heater drain tank pumps 21 and 22 tripped, apparently due to a failure of the automatic heater drain level control valves that could not be manually corrected from the single controller. Reactor operators reduced load in accordance with station procedures to respond to the trip of the heater drain tank pumps and stabilized reactor power at 77%. As a result of the required load reduction delta flux was outside of the operational limit envelope specified at 77% reactor power. This required a further load reduction to less than 50 percent as per Technical Specification 3.2.3. At approximately 68% percent power the reactor was manually tripped due to the mismatch of primary power and secondary load indications. The Auxiliary Feedwater System actuated following the manual trip as expected. This is reportable under 10 CFR 50.72(b)(3)(iv)(A). A high-high water level signal was received on the 22 Steam Generator. This was due to a feedwater regulating valve that did not fully close. The feedwater isolation valves closed. All other safety systems actuated as required and safety equipment operated as expected. The Emergency Diesel Generators did not start as offsite power remained available and stable. No primary or secondary relief valves lifted. The plant is in Hot Standby at normal temperature and pressure with residual heat removal using auxiliary feedwater and normal heat removal through the condenser via steam dumps. There was no radiation released. A post trip investigation will be performed prior to restart.</br>The licensee notified the NRC Resident Inspector.</br>*** UPDATE FROM GEORGE DAHL TO JOHN KNOKE AT 1830 EDT ON 08/23/06 ***</br>This is an update of non-emergency Event Notification 42797 that was previously made on August 23, 2006. Clarification is provided to include reporting of the Event Classification for actuation of a second system (automatic feedwater isolation) as an 8-Hr. Non-Emergency per 10 CFR 50.72(b)(3)(iv)(A). This update revises the wording as follows:</br>The feedwater isolation valve was manually closed. After receipt of the high-high level trip signal, 21, 23, and 24 feedwater isolation valves automatically closed. This is also reportable under 10 CFR 50.72(b)(3)(iv)(A).</br>The licensee notified the NRC Resident Inspector. Notified R1DO (Conte).esident Inspector. Notified R1DO (Conte).
14:35:00, 23 August 2006 +
42,797 +
13:19:00, 23 August 2006 +
14:35:00, 23 August 2006 +
On August 23, 2006, at 1035 hours, the Rea … On August 23, 2006, at 1035 hours, the Reactor Protection System was manually actuated while at reduced load of approximately 68 percent reactor power upon indication of an apparent disparity in net electric load. It was determined that the cyclic operation of the condenser steam dumps varied steam to the turbine resulting in the indicated drop in electrical output power from about 500 Mwe to 150 Mwe. The manual trip is reportable under 10 CFR 50.72(b)(2)(iv). The event started when heater drain tank pumps 21 and 22 tripped, apparently due to a failure of the automatic heater drain level control valves that could not be manually corrected from the single controller. Reactor operators reduced load in accordance with station procedures to respond to the trip of the heater drain tank pumps and stabilized reactor power at 77%. As a result of the required load reduction delta flux was outside of the operational limit envelope specified at 77% reactor power. This required a further load reduction to less than 50 percent as per Technical Specification 3.2.3. At approximately 68% percent power the reactor was manually tripped due to the mismatch of primary power and secondary load indications. The Auxiliary Feedwater System actuated following the manual trip as expected. This is reportable under 10 CFR 50.72(b)(3)(iv)(A). A high-high water level signal was received on the 22 Steam Generator. This was due to a feedwater regulating valve that did not fully close. The feedwater isolation valves closed. All other safety systems actuated as required and safety equipment operated as expected. The Emergency Diesel Generators did not start as offsite power remained available and stable. No primary or secondary relief valves lifted. The plant is in Hot Standby at normal temperature and pressure with residual heat removal using auxiliary feedwater and normal heat removal through the condenser via steam dumps. There was no radiation released. A post trip investigation will be performed prior to restart.</br>The licensee notified the NRC Resident Inspector.</br>*** UPDATE FROM GEORGE DAHL TO JOHN KNOKE AT 1830 EDT ON 08/23/06 ***</br>This is an update of non-emergency Event Notification 42797 that was previously made on August 23, 2006. Clarification is provided to include reporting of the Event Classification for actuation of a second system (automatic feedwater isolation) as an 8-Hr. Non-Emergency per 10 CFR 50.72(b)(3)(iv)(A). This update revises the wording as follows:</br>The feedwater isolation valve was manually closed. After receipt of the high-high level trip signal, 21, 23, and 24 feedwater isolation valves automatically closed. This is also reportable under 10 CFR 50.72(b)(3)(iv)(A).</br>The licensee notified the NRC Resident Inspector. Notified R1DO (Conte).esident Inspector. Notified R1DO (Conte).
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