05000416/LER-2015-003
| 12-13-2015 | At 12:20 on October 14, 2015, with the plant in MODE 1 at 100 percent rated core thermal power, Grand Gulf Nuclear Station identified a condition prohibited by the plant's Technical Specifications. Grand Gulf Nuclear Station failed to meet the requirements of Technical Specification 5.5.6, Inservice Testing Program, and Surveillance Requirement 3.6.1.3.9.
Specifically, three valves were not Local Leak Rate Tested at or greater than the required test pressure of 16.28 pounds per square inch guage, 110% of the Extended Power Uprate accident pressure. The cause of the inadequate Surveillance Testing was lack of post Extended Power Uprate testing criteria incorporation into Grand Gulf Surveillance Testing Procedures. Following the inadequate Surveillance Testing in 2013, the valves were subsequently leak rate tested at or greater than the required test pressure of 16.28 psig on October 15, 2015 and October 17, 2015. The subsequent leakage rate testing for all three valves was within the acceptance criteria of Technical Specification Surveillance Requirement 3.6.1.3.9. There was no actual impact to public health and safety due to this event. APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/3112018 Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by intemet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may collection. 366A U.S. NUCLEAR REGULATORY COMMISSION ContentsCONTINUATION SHEET2. DOCKET 3. LER NUMBER 05000 416 Initial Conditions: At the time of the event, Grand Gulf Nuclear Station (GGNS) was operating in MODE 1 at 100 percent rated core thermal power. There were no systems, structures or components that were inoperable at the start of the event that contributed to the event. Description of Event:Grand Gulf Nuclear Station Unit 1 Technical Specification (TS) Surveillance Requirement (SR) 3.6.1.3.9 requires Primary Containment Isolation Valves (PC1Vs) to be hydrostatically tested at 110% of accident pressure in accordance with the Inservice Testing Program. The inservice Testing Program is defined in TS 5.5.6. While reviewing Local Leak Rate Testing (LLRT) Procedures for outage preparation on October 14, 2015, it was discovered the Local Leak Rate Test Low Pressure Water procedure was not revised as a result of the Extended Power Uprate (EPU). A step in the procedure states the base test pressure is 12.65 psig (110% of peak accident pressure). The value of 12.65 psig is 110% of the pre-EPU peak accident pressure of 11.5 psig. The peak containment accident pressure was revised on July 18, 2012 when the Nuclear Regulatory Commission (NRC) approved the GGNS, Extended Power Uprate, License Amendment Request. The base test pressure should have been revised to 16.28 psig, 110% of the post-EPU peak accident pressure of 14.8 psig. The current testing criterion remains at the post-EPU value of 16.28 psig. Three valves were determined to have not been Local Leak Rate Tested at or greater than the required base test pressure of 16.28 psig. These three valves included two Refuel Water Transfer Pump Suction from Suppression Pool valves and a Residual Heat Removal (RHR) Sample Return Isolation valve. Upon discovery, the valves were declared inoperable and isolated in accordance with TS 3.6.1.3. The two Refuel Water Transfer Pump Suction valves were tested at or greater than the post-EPU base test pressure on October 15, 2015 and passed with zero leakage identified. The Residual Heat Removal Isolation valve was tested at or greater than the post-EPU base test pressure on October 17, 2015 and passed with zero leakage identified. After satisfactory testing was completed, all valves were declared operable. The Refuel Water Transfer Pump Suction valves were previously tested on June 25, 2008 and August 14, 2008 respectively with the appropriate pre-EPU test pressure of 12.9 psig. The test passed with zero leakage identified. The RHR Isolation valve was tested on April 15, 2008 with the appropriate pre-EPU test pressure of 13.0 psig. The test passed with zero leakage identified. Therefore, the valves were demonstrated operable at the 2008 tests. Next testing of the valves was in 2013. The valves were inappropriately tested at or greater than the pre-EPU base test pressure and passed with zero leakage identified. Cause of Event:The cause was determined to be inadequate incorporation of testing criteria into Surveillance Testing Procedure 06-0P-1M61-V-0003, Local Leak Rate Test Low Pressure Water. An Engineering Change was completed which evaluated the impacts of EPU on Containment Leakage Rate Testing. However, it did not identify Local Leak Rate Test Low Pressure Water as a procedure requiring change. This change was missed due to failure of personnel to follow the Engineering Change Process per station procedures. Necessary reviews were not completed and the required procedure change was not identified. Extent of Condition: Ten valves were identified that should have been hydrostatically tested at or above 16.28 psig per post- EPU conditions on a schedule specified by the Inservice Testing Program. Three of those valves were not tested at or above 16.28 psig during their most recent regularly scheduled surveillance test. These three APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by Internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may collection. NRC FORM366A U.S. NUCLEAR REGULATORY COMMISSION CONTINUATION SHEET2. DOCKET 3. LER NUMBER 05000 416 Valves are being reported under this Licensee Event Report (LER). The remaining seven valves were tested at or above 16.28 psig during their most recent regularly scheduled surveillance test. These seven valves passed the surveillance testing with satisfactory results. Therefore, there are no adverse conditions with the hydrostatic testing of the remaining seven valves. Twenty-two valves are High/Low Interface Valves and are required to be hydrostatically tested at or above 50 psig. The most recent water LLRT was reviewed for each valve and the test was conducted at or above 50 psig as required. Therefore, there are no adverse conditions with the hydrostatic testing of these High/Low Interface valves. Grand Gulf Nuclear Station documented all pneumatically tested valves have been tested at or above the post- EPU accident pressure with the exception of four valves. These four valves do not require pneumatic LLRT at the post-EPU accident pressure until their next regularly scheduled test. Two valves are scheduled for testing prior to July 2016 and two valves are scheduled for testing prior to March 2017. The testing schedule for valves was addressed in the GGNS EPU License Amendment Request and acceptance of the testing schedule as documented in the EPU NRC Safety Evaluation Report. Therefore, there are no additional vulnerabilities as shown by this extent of condition evaluation summary. Corrective Actions:Required Actions of TS 3.6.1.3 were entered and immediate actions were taken to declare the two Refuel Water Transfer Pump Suction from Suppression Pool valves and the RHR Sample Return Isolation valve inoperable. The valves were re-tested at or greater than 16.28 psig, 110% of the post-EPU accident pressure, on October 15, 2015 and October 17, 2015 and passed with zero leakage identified. The LLRT procedure which displayed the incorrect testing pressure will be revised to reflect the appropriate post-EPU base testing pressure. Evaluation of the human performance aspect of this event is ongoing. Correction of the causal factors of the human performance errors will eliminate reoccurrence of this type of event. A supplement to this report will be submitted in the event the evaluation leads to significant changes in the cause or corrective actions associated with this LER. Safety Significance:There were no actual nuclear safety or industrial safety consequences related to this event. There were no actual or potential radiological consequences as a result of this event. The October 15, 2015 and October 17, 2015 post-EPU pressure surveillance testing passed with zero leakage identified for all three valves. Passing the surveillance test at the appropriate post-EPU testing pressure demonstrated the PCIVs continuous operability. Due to the testing proving continuous safety function was maintained, this event will not be counted toward the GGNS Performance Indicator for Loss of Safety Function. Basis of Reportability: This LER is being submitted pursuant to Title 10 Code of Federal Regulation (10 CFR) 50.73(a)(2)(i)(B) for any operation or condition which was prohibited by plant Technical Specifications and 10 CFR 50.73 (a)(2)(v)(C) for any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to (C) control the release of radiological material. Telephonic notification was made to the U.S. Nuclear Regulatory Commission (NRC) Emergency Notification System (ENS) on October 14, 2015, pursuant to 10 CFR 50.72(b)(3)(v)(C). |
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| Grand Gulf Nuclear Station, Unit 1 | |
| Event date: | 10-14-2015 |
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| Report date: | 12-13-2015 |
| 4162015003R00 - NRC Website | |
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