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On July 26, 2006, at approximately 07:34 M … On July 26, 2006, at approximately 07:34 Mountain Standard Time (MST) Palo Verde Unit 2 experienced an automatic reactor scram on Variable Overpower. Unit 2 was operating at 90% power at normal operating temperature and pressure prior to the event. A main turbine control valve (CV02) was being returned to service following maintenance. CV02 initially started to open which caused reactor power to decrease to approximately 89%. During the evolution, six steam bypass control valve opened (three valves opened 100 percent, one opened 60 percent, and two opened 5 percent). Reactor power rapidly increased to 98% which resulted in an auxiliary Variable Power Trip (VOPT). The VOPT trip set point is 8 percent. The main turbine automatically tripped in response to the reactor trip. All rods inserted, as required. No ESF actuations occurred and none were required. </br>No emergency classification was required per the Emergency Plan. Safety related buses remained energized during and following the reactor trip. The Emergency Diesel Generators did not start and were not required. The offsite power grid is stable. No LCOs have been entered as a result of this event. No major equipment was inoperable prior to the event that contributed to the event. The maximum power level during the transient was approximately 98%.</br>Unit 2 is stable at normal operating temperature and pressure in Mode 3. The event did not result in any challenges to fission product barriers and there were no adverse safety consequences as a result of this event. The maximum RCS pressure was approximately 2260 psia (normal 2240). The maximum steam generator pressure was approximately 1090 psia (normal 1055). The event did not adversely affect the safe operation of the plant or the health and safety of the public.</br>The licensee notified the NRC Resident Inspector.ensee notified the NRC Resident Inspector. +
14:35:00, 26 July 2006 +
42,730 +
14:20:00, 26 July 2006 +
14:35:00, 26 July 2006 +
On July 26, 2006, at approximately 07:34 M … On July 26, 2006, at approximately 07:34 Mountain Standard Time (MST) Palo Verde Unit 2 experienced an automatic reactor scram on Variable Overpower. Unit 2 was operating at 90% power at normal operating temperature and pressure prior to the event. A main turbine control valve (CV02) was being returned to service following maintenance. CV02 initially started to open which caused reactor power to decrease to approximately 89%. During the evolution, six steam bypass control valve opened (three valves opened 100 percent, one opened 60 percent, and two opened 5 percent). Reactor power rapidly increased to 98% which resulted in an auxiliary Variable Power Trip (VOPT). The VOPT trip set point is 8 percent. The main turbine automatically tripped in response to the reactor trip. All rods inserted, as required. No ESF actuations occurred and none were required. </br>No emergency classification was required per the Emergency Plan. Safety related buses remained energized during and following the reactor trip. The Emergency Diesel Generators did not start and were not required. The offsite power grid is stable. No LCOs have been entered as a result of this event. No major equipment was inoperable prior to the event that contributed to the event. The maximum power level during the transient was approximately 98%.</br>Unit 2 is stable at normal operating temperature and pressure in Mode 3. The event did not result in any challenges to fission product barriers and there were no adverse safety consequences as a result of this event. The maximum RCS pressure was approximately 2260 psia (normal 2240). The maximum steam generator pressure was approximately 1090 psia (normal 1055). The event did not adversely affect the safe operation of the plant or the health and safety of the public.</br>The licensee notified the NRC Resident Inspector.ensee notified the NRC Resident Inspector. +
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