Semantic search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 55459 | 13 September 2021 22:22:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Unanalyzed Condition of Fire Safe Shutdown Equipment | On September 13, 2021, at 1822 EDT, an apparent non-compliance with 10 CFR 50, Appendix R, section III.G.2 (separation of redundant fire safe shutdown equipment) was identified. Specifically, it was determined that some Emergency Diesel Generator (EDG) cables may be susceptible to a hot short/spurious operation to the close circuit. A spurious closure of the emergency bus normal supply breakers after the EDG is powering the bus could result in non-synchronous paralleling, EDG overloading, or EDG output breaker tripping due to faulted power cable from normal supply breaker. The spurious closure of the normal supply breakers is not currently addressed in the Appendix R Report or previous Multiple Spurious Operations (MSO) analysis. This condition is associated with the Appendix R safe-shutdown function of the Emergency Power System. The Emergency Power System is considered operable but not fully qualified for its safety-related design function. The following fire areas are impacted: 1) Fire Area 13, Unit 1 Normal Switchgear Room 2) Fire Area 46, Unit 1 Cable Tray Room 3) Fire Area 3, Unit 1 Emergency Switchgear and Relay Room 4) Fire Area 2, Unit 2 Cable Vault and Tunnel Until this condition is analyzed, Surry has implemented mitigating actions in the above fire areas. This condition is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(B). This is also reportable as a 60-day written report pursuant to 10 CFR 50.73(a)(2)(ii)(B). This event was entered into the licensee's Corrective Action Program as CR (condition report) 1180502. The NRC Resident Inspector has been notified of this event. Mitigating actions include posting fire watches in the affected areas. | Emergency Diesel Generator | |
| ENS 54437 | 11 December 2019 18:56:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Potential Tornado Missile Vulnerabilities | On December 11, 2019, at 1356 EST, it was concluded that certain safety-related equipment is vulnerable to design basis tornado missiles which could render the equipment inoperable and not able to perform its design function. This applies to the following Technical Specification equipment: 1. Component cooling water piping for the 'A' spent fuel cooling water system heat exchanger. This heat exchanger is vulnerable to a horizontal missile traveling through the roll-up door, which would challenge operability of the Technical Specification required component cooling system equipment. 2. All three (3) emergency service water pumps and their diesel fuel oil supply tank. The emergency service water pumps and diesel fuel oil tank are vulnerable to a horizontal missile penetrating the missile screens. 3. Certain component cooling water system pump discharge piping is vulnerable from a vertical missile penetrating the auxiliary building roof. 4. The Unit 1 auxiliary feedwater (AFW) system pumps and the pump suction and discharge piping are vulnerable to a missile traveling through the screens on the sides and roof of the main steam valve house. This vulnerability also exists for the Unit 2 AFW. This condition puts Unit 1 and 2 into Technical Specification 3.01 which requires the units to be in hot shutdown within 6 hours and in cold shutdown within the following 30 hours. The NRC Resident Inspector has been notified. | Service water Auxiliary Feedwater Main Steam | |
| ENS 40770 | 22 May 2004 01:46:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Unanalyzed Condition Due to Auxiliary Feedwater Not Being in Compliance with Justification for Continued Operation (Jco). | At 2146 hours on 05/21/04, Unit 2 entered a 30 Hr. clock to Cold Shutdown (CSD) in accordance with T.S.3.0.1 due to Auxiliary Feedwater (AFW) not being in compliance for Continued Operation (JCO) SC 03-002 configuration. Auxiliary Feedwater was declared inoperable at 2146 hours. During post trip recovery, Emergency Procedure, 2-ES-0.1, directed that the six (6) AFW motor operated valves (MOVs) be checked opened after securing the AFW Pumps. This is contrary to the AFW JCO, which requires four (4) MOVs out of six (6) to be closed for AFW to remain Operable. At 0040 hours on 5/22/04 the correct valve alignment in accordance with the JCO was established and the 30 hour TS 3.0.1 clock was exited. This event is reportable in accordance with 10CFR50.72(b)(3)(ii)(B); any event or condition that results in the Station being in an unanalyzed condition that significantly degrades plant safety. The NRC resident has been notified. The licensee found out about this event today during event investigation. See Surry Unit 2 events 40769, 40768 and 40771.
The following information was received from the licensee via facsimile: At 1506 hours on 5/22/04, Surry Power Station made an 8-hour Non-Emergency Notification in accordance with 10CFR50.72 (b)(3)(ii)(B) for an unanalyzed condition due to Auxiliary Feedwater (AFW) not being aligned in accordance with Justification for Continued Operation (JCO) SC 03-002 for 2 hours and 54 minutes following a reactor trip. (Event Number 40770). Upon further analysis, this event was determined not to be immediately reportable. Based on calculations performed by Dominion Nuclear Safety Analysis in Engineering Transmittal ET NAF-04-0045, Rev 0, a risk-based period of time was calculated to allow operations personnel a defined period of time to realign the AFW system in accordance with this JCO. Operators must not exceed 150 hours to restore the acceptable JCO configuration during all modes where AFW is required to be operable. Since the amount of time the system was not in the JCO alignment was less than 150 hours, plant risk increase was maintained less than the limits specified in Regulatory Guide 1.177. This notification is being made to retract the report made on 5/22/04 based on the above discussion. The NRC resident has been notified. The NRC Headquarters Operations Officer notified R2DO (Ayres). | Auxiliary Feedwater | |
| ENS 40389 | 12 December 2003 16:19:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Both Trains of Auxiliary Feewater Were Declared Inoperable for One Hour and 22 Minutes. | Surry Power Station has determined that an unanalyzed condition related to Auxiliary Feedwater (AFW) isolation during a steam generator tube rupture (SGTR) event exists. The existing accident analysis for a SGTR requires that AFW to the ruptured steam generator (SG) be isolated prior to the water level in that SG rising into the main steam pipe. Failing to take these actions could result in a radioactive release or failure of equipment important to safety, which has not been previously analyzed. The current configuration of the AFW system has six motor operated valves (MOVs), two for each SG, which are used to control flow from one of two AFW headers. Three MOVs are powered from "H" emergency bus and three MOVs are powered from "J" emergency bus. The MOVs are maintained normally open. With a loss of emergency power to either train of AFW MOVs, the control room operators are not able to close the three MOVs from the de-energized emergency bus without manual action inside containment. A review of the plant safety analysis design basis indicates that with this AFW configuration, isolation of AFW to a ruptured SG would not be possible within the time frame specified in the analysis. Unit One and Unit Two entered a TS 3.0.1 clock at 1119 hours on December 12, 2003 due to the AFW systems being declared inoperable. The station took immediate actions to address the configuration control issue in order to meet the assumptions made in the SGTR accident analysis and both Unit One and Unit Two exited the TS 3.0.1 clock at 13:41 hours on December 12, 2003. The NRC Resident Inspector was notified of this event by the licensee. | Steam Generator Auxiliary Feedwater Main Steam | |
| ENS 40292 | 3 November 2003 22:20:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Non-Conservatism in Design Methodology for Loss of Rcp (Reactor Coolant Pump) Seal Cooling | The design data used to support Dominion's methodology to cope with a loss of (RCP) seal cooling (which was based on Westinghouse WCAP-10541 Rev. 2) may be non-conservative. The NRC issued an SER on Westinghouse report WCAP-15603 that indicates data from this new model must consider a 20% probability that the hot RCP seals may result in up to 182 gpm leakage per pump if seal cooling is lost for more than 13 minutes. Assuming this higher leak rate, the requirements of Appendix R, Section III.L, cannot be met since Pressurizer level could not be maintained. Current methodology indicates Surry will lose charging and seal cooling for greater than 13 minutes from a fire in the Emergency Switchgear Room. This report is being made pursuant to 10 CFR 50.72 (b)(3)(ii)(B). The NRC resident (inspector) was notified of this condition. |