November 15, 2007
NRC INFORMATION NOTICE 2007-36:EMERGENCY DIESEL GENERATOR VOLTAGEREGULATOR PROBLEMS
ADDRESSEES
All holders of operating licenses for nuclear power reactors, except those who havepermanently ceased operations and have certified that fuel has been permanently removed from the reactor vessel.
PURPOSE
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to informaddressees of recent operating experiences involving the emergency diesel generator (EDG)
voltage regulator problem The NRC expects that recipients will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problem Suggestions contained in this IN are not NRC requirements; therefore, no specific action or written response is required.DESCRIPTION OF CIRCUMSTANCESThere have been recent operating experiences with EDG voltage regulator problems at thefollowing nuclear stations:Seabrook Generating StationOn August 30, 2006, during a fast start test of the "A" EDG, the EDG voltage regulator diodefailure warning light illuminate Data obtained at test points within the EDG voltage regulator indicated that there were anomalies with the gate firing circuit output pulses to the silicon controlled rectifiers (SCRs) on the rectifier assembl On September 27, 2006, the "A" EDG experienced an additional diode failure light illuminatio The subsequent troubleshooting determined that the K1 contactor was defective with one phase not making ideal contact. During surveillance testing of the "B" EDG on August 31, 2006, the EDG voltage regulatordiode failure light illuminated and the EDG output voltage failed high and could not be controlled in the automatic mod Initial troubleshooting of the "B" EDG voltage regulator failure identified degradation in one of the seven capacitors in the power chassi The licensee's root cause evaluation for this event discussed that the "B" EDG at Seabrook Station had a history of intermittent overvoltage problems, including two overvoltage events in 200 The evaluation ML072780394 IN 2007-36
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| list | - Information Notice 2007-03, Reportable Medical Events Involving Patients Receiving Dosages of Sodium Iodide Iodine-131 Less than the Prescribed Dosage Because of Capsules Remaining in Vials After Administration (2 February 2007, Topic: Enforcement Discretion)
- Information Notice 2007-03, Reportable Medical Events Involving Patients Receiving Dosages of Sodium Iodide Iodine-131 Less Than the Prescribed Dosage Because of Capsules Remaining in Vials After Administration (2 February 2007, Topic: Tritium Exit Sign)
- Information Notice 2007-04, Construction Experience Related to the Assurance of Quality in the Construction of Nuclear Power Plants (5 February 2007)
- Information Notice 2007-05, Vertical Deep Draft Pump Shaft and Coupling Failures (9 February 2007, Topic: Ultimate heat sink)
- Information Notice 2007-06, Potential Common Cause Vulnerabilities in Essential Service Water Systems (9 February 2007, Topic: Ultimate heat sink, Probabilistic Risk Assessment, Coatings, Biofouling, Through-Wall Leak)
- Information Notice 2007-07, Potential Failure of All Control Rod Groups to Insert in a Boiling Water Reactor (BWR) Due to a Fire (15 February 2007, Topic: Hot Short, Safe Shutdown, Shutdown Margin, Fire Protection Program, Backfit)
- Information Notice 2007-08, Potential Vulnerabilities of Time-Reliant Computer-Based Systems Due to Change in Daylight Saving Time Dates (28 February 2007)
- Information Notice 2007-09, Equipment Operability Under Degraded Voltage Conditions (26 March 2007)
- Information Notice 2007-10, Yttritium-90 TheraSpheres and SirSpheres Impurities (2 March 2007, 15 March 2007, Topic: Tritium Exit Sign)
- Information Notice 2007-10, Yttritium-90 Theraspheres and Sirspheres Impurities (2 March 2007, Topic: Enforcement Discretion)
- Information Notice 2007-11, Recent Operator Performance Issues at Nuclear Power Plants (6 March 2007, Topic: Time of Discovery)
- Information Notice 2007-12, Tactical Communications Interoperability Between Nuclear Power Reactor Licensees and First Responders (15 March 2007)
- Information Notice 2007-14, Loss of Offsite Power and Dual-Unit Trip at Catawba Nuclear Generating Station (30 March 2007)
- Information Notice 2007-15, Effects of Ethernet-based, Non-Safety Related Controls on the Safe and Continued Operation of Nuclear Power Stations (17 April 2007)
- Information Notice 2007-17, Fires at Nuclear Power Plants Involving Inadequate Fire Protection Administrative and Design Controls (3 May 2007, Topic: Safe Shutdown, Fire Barrier, Operator Manual Action, Continuous fire watch, Fire Protection Program, Fire Watch, Hourly Fire Watch)
- Information Notice 2007-18, Operating Experience Regarding Entrainment of Gas or Debris Into Auxiliary Feedwater Systems (13 May 2007, Topic: Design basis earthquake)
- Information Notice 2007-18, Operating Experience Regarding Entrainment of Gas or Debris into Auxiliary Feedwater Systems (13 May 2007, Topic: Foreign Material Exclusion)
- Information Notice 2007-20, Use of Blank Ammunition (11 June 2007)
- Information Notice 2007-21, Pipe Wear Due to Interaction of Flow-Induced Vibration and Reflective Metal Insulation (11 December 2020, Topic: VT-2, Liquid penetrant)
- Information Notice 2007-22, Recent Hydrogen Fluoride Exposures at Fuel Cycle Facilities (19 June 2007)
- Information Notice 2007-23, Inadvertent Discharge of Halon 1301 Fire Suppression System Due to Incorrect and/or Out of Date Procedures (8 August 2007, Topic: Fire Protection Program)
- Information Notice 2007-23, Inadvertent Discharge of Halon 1301 Fire Suppression System Due to Incorrect And/Or Out of Date Procedures (8 August 2007, Topic: Fire Protection Program)
- Information Notice 2007-24, Summary of Fitness-for-Duty Program Performance Reports for Calendar Year 2006 (19 July 2007, Topic: Fitness for Duty, Contraband)
- Information Notice 2007-25, Recommendations From the Advisory Committee on the Medical Use of Isotopes for Improved Compliance with 10 CFR 35.40 and 35.27 (19 July 2007, Topic: Tritium Exit Sign)
- Information Notice 2007-25, Recommendations from the Advisory Committee on the Medical Use of Isotopes for Improved Compliance with 10 CFR 35.40 and 35.27 (19 July 2007, Topic: Enforcement Discretion)
- Information Notice 2007-26, E-mail from Alex Klein to Alex Marion Regarding NRC Information Notice 2007-26 (17 December 2007, Topic: Coatings)
- Information Notice 2007-27, Recurring Events and Trends Involving Emergency Diesel Generator Operability (6 August 2007, Topic: Preliminary White Finding)
- Information Notice 2007-28, Potential Common Cause Vulnerabilities in Essential Service Water Systems Due to Inadequate Chemistry Controls (19 September 2007, Topic: Probabilistic Risk Assessment, Frazil ice, Biofouling)
- Information Notice 2007-29, Temporary Scaffolding Affects Operability of Safety-Related Equipment (17 September 2007, Topic: Fire Protection Program, Scaffolding)
- Information Notice 2007-30, Radiological Controls Create Criticality Safety Accident Scenario for Fissile Solution Container Transport at Fuel Cycle Facility (13 September 2007, Topic: Coatings)
- Information Notice 2007-31, U.S. Food and Drug Administration Announcement Related to Sleep Disorder Drugs (13 November 2007, Topic: Fitness for Duty, Coatings)
- Information Notice 2007-32, Out of Service Equipment Connected to in Service Process Line Results in Fissile Solution Spill at Fuel Cycle Facility (15 October 2007, Topic: Hydrostatic, Coatings)
- Information Notice 2007-32, Out of Service Equipment Connected To In Service Process Line Results in Fissile Solution Spill at Fuel Cycle Facility (15 October 2007, Topic: Hydrostatic, Coatings)
- Information Notice 2007-34, Operating Experience Regarding Electrical Circuit Breakers (22 October 2007)
- Information Notice 2007-36, Emergency Diesel Generator Voltage Regulator Problems (15 November 2007)
- Information Notice 2007-37, Buildup of Deposits in Steam Generators (23 November 2007)
- Information Notice 2007-38, Ensuring Complete and Accurate Information in the Documentation of Training and Experience for Individuals Seeking Medical Authorization Under the Alternate Pathway (14 December 2007)
- Information Notice 2007-40, Inadequate Implementation of 10 CFR Part 21 Requirements by Vendors Who Supply Basic Components to Nuclear Power Plant Licensees (21 December 2007)
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