Semantic search

On September 15, 2014, with Unit 2 defueled, debris that had the potential to be fuel fragments was located on the core plate directly below the B11 core location, where fuel assembly 4Z9 resided during Cycle 23.

Video inspection of fuel assembly 4Z9 identified that the top springs of two fuel pins were dislodged. Due to the fact that the fuel damage exceeded expected conditions, at 1454 on September 15, 2014, this event was reported as an eight hour report as per 10 CFR 50.72(b)(3)(ii)(A), any event or condition that results in the condition of the nuclear plant, including its principle safety barriers, being seriously degraded. Detailed video inspections estimated that 15 fuel pellets were dislodged from fuel assembly 4Z9. During efforts to identify and recover the fuel pellets, 7 fuel pellets worth of material were not found and have already or are expected to granulate into fine particles that will dissolve in low flow areas of the primary plant systems, or be removed by normal purification processes. Since the specific location of the 7 fuel pellets is undesignated and because those pellets contain licensed material in a quantity greater than 10 times the quantity specified in App. C of 10 CFR 20, a report was made at 1227 on September 30, 2014, pursuant to 10 CFR 74.11(a) and to 10 CFR 20.2201(a)(ii). The health and safety of the public were not affected by this event.

annunciator, 2G-B5 "Station Service Busses 2A-2B-2C UV Relay Trouble" alarmed and locked in. Troubleshooting indicated that the under voltage (UV) relay monitoring B-C phase for Station Service Bus 2A had actuated. The 2A UV channel was placed into trip on July 3, 2013, per Technical Specification 3.3.1 Condition L, but the 2A under frequency (UF) channel was not placed into trip. On July 3, 2013, a multidiscipline team, including the vendor, determined that the UF relay would remain operable with the degraded voltage. An Operability Determination was developed and approved to document the conclusion. However, on July 10, 2013, it was revealed through additional testing that the operability determination contained inaccurate information and the 2A UF relay would not operate within the required time frame. The 2A UF relay channel was subsequently placed in trip on July 10, 2013. A potential transformer blown fuse was replaced and the UV and UF channels were restored to operable on July 22, 2013.

This event is reportable pursuant to 10CFR50.73(a)(2)(i)(B) for a condition prohibited by Technical Specifications (TS) when the inoperable UF channel was not placed into trip within the time limits of TS. The health and safety of the public were not affected by the event.

On August 23, 2011, at 1440 hours with Units 1 and 2 offline, as a result of the Central Virgirfa earthquake, the Unit 2 "H" (2H) emergency diesel generator (EDG) was manually tripped due to a coolant system leak forty-nine minutes after its demand start due to a loss of offsite power. A Root Cause Evaluation determined the 2H EDG could have developed a coolant leak during its next operation (i.e., post maintenance or periodic testing or a demand start). On September 28, 2011 a completed prior operability evaluation determined the 2H EDG gasket failure resulted in fault exposure unavailable hours totaling 337.6 hours. During the fault exposure unavailable hours, approximately fourteen days, the limiting action of TS 3.8.1.b was entered three times.

Had a demand start of the 2H EDG occurred during any of these times the gasket failure could have occurred resulting in more than one inoperable EDG. This event is reportable pursuant to 10 CFR 50.73(a)(2)(v)(A), 50.73(a)(2)(v)(B), and 50.73(a)(2)(v)(D) for a condition that could have prevented fulfillment of the safety function of a system required to maintain the reactor in a safe shutdown condition, remove residual heat, and mitigate the consequences of an accident.

The event posed no significant safety implications and the health and safety of the public were not affected by the event.

On May 28, 2010, at 0004 hours North Anna Unit 2 experienced an automatic Reactor trip from 100 percent power following a lightning strike in the switchyard. A combination of events precluded the transfer of the "B" Station Service (SS) bus to the "B" Reserve Station Service Transformer (RSST), 'resulting in the "B" SS bus being de-energized and a consequential loss of power to Unit 2 reactor coolant pump 1B (2-RC-P-1B). Unit 2 tripped on low flow in the "B" RCS loop. All available Engineered Safety Feature equipment responded as designed. A non-emergency 4-hour report was made to the NRC Operations Center at 0323 hours on May 28, 2010, in accordance with 10 CFR 50.72(b)(2)(iv)(B). An 8-hour report was also made in accordance with 10 CFR 50.72(b)(3)(iv)(A) due to actuation of the Auxiliary Feedwater System (AFW). This event is reportable pursuant to 10 CFR 50.73(a)(2)(iv)(A) for a condition that resulted in automatic actuation of the reactor protection system and the AFW system. This event posed no significant safety implications since the reactor protection system functioned to trip the reactor. Therefore, the health and safety of the public were not affected by this event.

On February 8, 2008, Unit 2 was in Mode 3, zero percent power, preparing for restart following a planned maintenance outage. At 1759 hours, a rod control urgent failure alarm was received while withdrawing the "A" Shutdown Bank control rods. Rod withdrawal was stopped and it was noted that the Group Step Counters deviated by three steps.A As a result, at 1812 hours a manual reactor trip was initiated by opening the reactor trip breakers in accordance with Technical Requirement 3.1.3. This is a valid actuation of the Reactor Protection System. Four suspect cards were replaced in Power Cabinet 2AC.

Following card replacement the reactor trip breakers were closed.A Shutdown Banks "A" and "B" were fully withdrawn with no concerns. On February 8, 2008, at 1959 hours, a non- emergency 8-hour report was made in accordance with 10 CFR 50.72(b)(3)(iv)(A) due to actuation of the Reactor Protection System. This event is reportable pursuant to 10 CFR 50.73A (a)(2)(iv)(A) for aA condition thatA resulted inAA manualA actuationA of theA Reactor Protection System. This event posed no significant safety implications because the reactor was subcritical when the reactor trip breakers were opened. Compliance with all Technical Requirements was maintained. Therefore, the health and safety of the public were not affected by this event.

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