08-03-2017 | On June 5, 2017, BSEP received the results of testing of eleven main steam line safety relief valves ( SRVs) removed from Unit 2 during the spring refueling outage. Three of the eleven valves were found to have as-found lift setpoints of their pilot valves outside the +/-3 percent tolerance required by Technical Specification (TS) 3.4.3.
One SRV was 9.1 percent high. One SRV was 8.6 percent high, and one SRV was 5.0 percent high. Evaluation determined that the elevated lift pressures in two valves resulted from corrosion bonding of the SRV pilot valves which raised the breakaway force needed to open the pilot. The third valve experienced steam erosion. This event had no adverse impact on nuclear safety. Although the SRV setpoint limits required by the TS were exceeded, the plant condition was bounded by the Brunswick Unit 2 Cycle 22 Reload Safety Analysis, demonstrating that the SRVs could have performed their safety function of limiting reactor vessel overpressure. TS 3.4.3 requires ten of the eleven installed SRVs to be operable. Since less than ten SRVs were operable, this event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) for operation prohibited by the plant's TS. The SRV pilot valves were replaced with certified spares before the startup of Unit 2. A procedure was revised to reduce corrosion bonding by improving surface preparation of SRV pilot valve discs. |
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Category:Letter
MONTHYEARIR 05000324/20230112023-12-26026 December 2023 NRC Fire Protection Team Inspection - FPTI Report 05000324/2023011 and 05000325/2023011 IR 05000324/20234022023-12-14014 December 2023 Security Baseline Inspection Report 05000324-2023402 and 05000325-2023402 ML23297A0262023-11-27027 November 2023 Proposed Alternatives to ASME Code Section XI Subsection IWE Requirements for Torus Metallic Liner Inspections ML23317A3462023-11-14014 November 2023 Duke Fleet - Correction Letter to License Amendment Nos. 312 & 340 Issuance of Amendments Regarding the Adoption of Technical Specifications Task Force Traveler TSTF-554, Revision 1 IR 05000324/20230032023-11-0101 November 2023 Integrated Inspection Report 05000324/2023003 and 05000325/2023003 IR 05000324/20230102023-10-17017 October 2023 Biennial Problem Identification and Resolution Inspection Report 05000324/2023010 and 05000325/2023010 IR 05000325/20234012023-10-16016 October 2023 Security Baseline Inspection Report 05000324 and 05000325 2023401 ML23346A1322023-10-0606 October 2023 Communication from C-10 Research & Education Foundation Regarding NextEra Common Emergency Fleet Plan License Amendment Request and Related Documents Subsequently Published ML23256A0882023-09-25025 September 2023 Issuance of Alternative to Steam Generator Welds ML23195A0782023-08-29029 August 2023 Issuance of Amendments Regarding the Adoption of Technical Specifications Task Force Traveler TSTF-554, Revision 1 IR 05000324/20230052023-08-23023 August 2023 Updated Inspection Plan for Brunswick Steam Electric Plant, Units 1 and 2 (Report 05000324/2023005 and 05000325/2023005) IR 05000324/20230022023-08-0404 August 2023 Integrated Inspection Report 05000324/2023002 and 05000325/2023002 ML23201A2042023-07-28028 July 2023 Summary of Regulatory Audit in Support of Alternative Request RA-22-0308 for Inservice Inspection of the Torus Metallic Liner ML23212B2682023-07-25025 July 2023 Notification of Licensed Operator Initial Examination 05000325/2024301 and 05000324/2024301 IR 05000324/20243012023-07-25025 July 2023 Notification of Licensed Operator Initial Examination 05000325/2024301 and 05000324/2024301 ML23146A0012023-05-24024 May 2023 EN 56538 - Engine Systems Inc and Brunswick ML23212A9502023-05-24024 May 2023 Engine Systems, Inc., Part 21 Report Re Woodward EGB-35P Governor/Actuator with Foreign Material ML23130A3902023-05-12012 May 2023 Regulatory Audit Plan in Support of Alternative Request RA 22-0308 for Inservice Inspection of the Torus Metallic Liner IR 05000324/20230012023-05-10010 May 2023 Integrated Inspection Report 05000324 2023001 and 05000325 2023001 ML23118A0762023-05-0101 May 2023 Approval for Use of Specific Provision of a Later Edition of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section XI IR 05000324/20220042023-04-0404 April 2023 Reissue - Brunswick Steam Electric Plant - Integrated Inspection Report 05000324/2022004 and 05000325/022004 ML22332A4932023-03-10010 March 2023 William States Lee III 1 and 2 - Issuance of Amendments Regarding the Relocation of the Emergency Operations Facility IR 05000324/20220062023-03-0101 March 2023 Annual Assessment Letter for Brunswick Steam Electric Plant, Units 1 and 2 NRC Inspection Reports 05000324/2022006 and 05000325/2022006 ML23033A5252023-02-0808 February 2023 Integrated Inspection Report 05000324/2022004 and 05000325/2022004 IR 05000324/20223012023-02-0303 February 2023 NRC Operator License Examination Report 05000325/2022301 and 05000324/2022301 ML22332A0132022-11-23023 November 2022 Operator Licensing Written Examination Approval 05000325/2022301 and 05000324/2022301 IR 05000324/20224022022-11-23023 November 2022 Security Baseline Inspection Report 05000324 2022402 and 05000325 2022402 ML22096A0032022-11-18018 November 2022 McGuire Nuclear Station and Shearon Harris Nuclear Power Plant Authorization of RA-19-0352 Regarding Use of Alternative for RPV Head Closure Stud Examinations ML22256A2532022-11-14014 November 2022 Issuance of Amendments Regarding the Adoption of Technical Specifications Task Force Traveler TSTF-541, Rev. 2 IR 05000324/20224032022-11-10010 November 2022 Cyber Security Inspection Report 05000324/2022403 and 05000325/2022403 ML22307A1762022-11-0707 November 2022 Notification of an NRC Fire Protection Team Inspection (FPTI) IR 05000324/20220032022-11-0707 November 2022 Integrated Inspection Report 05000324/2022003 and 05000325/2022003 ML22258A0302022-09-15015 September 2022 Evacuation Time Estimate Reports IR 05000324/20220052022-08-24024 August 2022 Updated Inspection Plan for Brunswick Steam Electric Plant (Report 05000324/2022005 and 05000325/2022005) ML22230D0692022-08-22022 August 2022 Documentation of the Completion of Required Actions Taken in Response to the Lessons Learned from the Fukushima Dai-ichi Accident IR 05000324/20220022022-08-0505 August 2022 Integrated Inspection Report 05000324/2022002 and 05000325/2022002 IR 05000324/20220102022-06-27027 June 2022 Design Basis Assurance Inspection (Teams) Inspection Report 05000324 2022010 and 05000325 2022010 ML22028A1742022-05-12012 May 2022 Issuance of Amendment Nos. 309 and 337 Regarding the Adoption of Technical Specifications Task Force Traveler TSTF-580, Revision 1 IR 05000324/20220012022-05-10010 May 2022 Integrated Inspection Report 05000324/2022001 and 05000325/2022001 ML22119A1352022-05-0909 May 2022 Information Request for the Cyber-Security Baseline Security Inspection, Notification to Perform Inspection 05000325/2022403; 05000324/2022403 ML22082A2682022-05-0202 May 2022 Issuance of Amendment Nos. 308 and 336 Regarding the Adoption of Technical Specifications Task Force Traveler TSTF-505, Revision 2 ML22102A0502022-04-11011 April 2022 301 Corporate Notification Letter IR 05000324/20224012022-03-16016 March 2022 Security Baseline Inspection Report 05000324/2022401 and 05000325/2022401 ML22054A2152022-03-0808 March 2022 Correction to Amendments to Revise Standby Liquid Control System Boron Solution Storage Tank Volume Technical Specifications IR 05000324/20210062022-03-0202 March 2022 Annual Assessment Letter for Brunswick Steam Electric Plant, Units 1 and 2 (Reports No. 05000324/2021006 and 05000325/2021006) IR 05000324/20210042022-02-14014 February 2022 Integrated Inspection Report 05000324/2021004 and 05000325/2021004 ML22035A1262022-02-0909 February 2022 Withdrawal of Exemption Request from the Requirements of 10 CFR Part 50, Appendix E, Section IV.F.2.d (EPID L-2021-LLE-0055 (COVID-19)) ML21354A5032022-01-24024 January 2022 Requested Exemption from 10 CFR 50, Appendix E, Section IV.F.2.D Not Required (EPID L-2021-LLE-0055 (COVID-19)) ML22018A1842022-01-18018 January 2022 Notification of Brunswick Steam Electric Plant, Units 1 & 2 - Design Bases Assurance Inspection - U.S. Nuclear Regulatory Inspection Report 05000324/2022010 and 05000325/2022010 ML21348A7192021-12-21021 December 2021 Regulatory Audit Summary Regarding License Amendment Request to Revise Technical Specifications to Adopt Risk-Informed Completion Times 2023-09-25
[Table view] Category:Licensee Event Report (LER)
MONTHYEAR05000324/LER-2017-0032017-08-0303 August 2017 1 OF 4, LER 17-003-00 for Brunswick, Unit 2, Regarding Setpoint Drift in Main Steam Line Safety/Relief Valves Results in Three Valves Inoperable, 05000325/LER-2017-0032017-08-0202 August 2017 Control Room Air Conditioning and Emergency Ventilation Systems Rendered Inoperable, LER 17-003-00 for Brunswick, Unit 1, Regarding Control Room Air Conditioning and Emergency Ventilation Systems Rendered Inoperable 05000324/LER-2017-0022017-06-12012 June 2017 Plant Mode Change with Primary Containment Inoperable, LER 17-002-00 for Brunswick, Unit 1, Regarding Foreign Material in Switch Results in Unplanned Automatic Start of Emergency Diesel Generators 05000324/LER-2017-0012017-05-18018 May 2017 Implementation of Enforcement Guidance Memorandum (EGM) 11-003, Revision 3, LER 17-001-00 for Brunswick, Unit 2, Regarding Implementation of Enforcement Guidance Memorandum (EGM) 11-003, Revision 3 05000324/LER-2016-0012016-08-0808 August 2016 Mispositioned Valves Result in Residual Heat Removal Service Water System Inoperability, LER 16-001-00 for Brunswick Steam Electric Plant, Unit 2, Regarding Mispositioned Valves Result in Residual Heat Removal Service Water System lnoperability 05000325/LER-2016-0032016-05-0202 May 2016 Implementation of Enforcement Guidance Memorandum (EGM) 11-003, Revision 3, LER 16-003-00 for Brunswick Steam Electric Plant, Unit 1 Regarding Implementation of Enforcement Guidance Memorandum (EGM) 11-003, Revision 3 05000324/LER-2016-0022016-05-0202 May 2016 High Pressure Coolant Injection System Inoperable due to Failed Relay Coil, LER 16-002-00 for Brunswick Steam Electric Plant (BSEP), Units 1 and 2, Regarding Emergency Diesel Generator 3 Inoperable Due to Failure to Auto-Start 05000325/LER-2016-0012016-04-0606 April 2016 Electriqal Bus Fault Results in Lockout of Startup Auxiliary Transformer and Loss of Offsite Power, LER 16-001-00 for Brunswick, Unit 1, Regarding Electrical Bus Fault Results in Lockout of Startup Auxiliary Transformer and Loss of Offsite Power BSEP 15-0088, Special Report, Technical Specification 5.6.6, Post Accident Monitoring (PAM) Instrumentation Report2015-10-22022 October 2015 Special Report, Technical Specification 5.6.6, Post Accident Monitoring (PAM) Instrumentation Report ML1019404522008-06-0303 June 2008 10CFR50.75g File: AR00237296 Overflowed CST ML1019404542008-05-13013 May 2008 10CFR50.75g File: AR00272173 Thru Wall Leak in Cw Intake Pipe Was Found to Contain Tritium in the Groundwater Leaking Into the Pipe ML1019404562008-04-28028 April 2008 10CFR50.75g File: AR00242461 Routine Environmental Soil/Water Sampling Has Identified Low Levels of Tritium . BSEP 03-0023, LER 2002-02-00 from Brunswick, Unit 2 Regarding Remote Shutdown Panel Power Supply Inventer Design Deficiency2003-02-14014 February 2003 LER 2002-02-00 from Brunswick, Unit 2 Regarding Remote Shutdown Panel Power Supply Inventer Design Deficiency 2017-08-03
[Table view] |
At the time the condition was identified, Unit 2 was in Mode 1 at 87 percent of rated power and was increasing in power after a preplanned control rod improvement evolution.
valves (SRVs) to be operable. Per Surveillance Requirement (SR) 3.4.3.1, each valve is required to open within +/-3 percent of its opening setpoint. As-found testing of the valves indicated that three of the valves had lift setpoints outside this tolerance. Based on the causes of the inoperability described below, it was concluded that three SRVs were inoperable when the unit was in operation. Consequently, the plant operated in a condition which is prohibited by the TS, that is, with fewer than the required number of SRVs having lift setpoints within the +/-3 percent tolerance. Therefore, the condition is being reported per 10 CFR 50.73(a)(2)(i)(B) for operation in a condition prohibited by the plant TSs.
The change in SRV lift setpoints resulted from corrosion bonding between the discs and seats of the pilot valves. Corrosion bonding between the pilot disc and seat is an inherent problem with the two-stage SRV During the spring 2017 Unit 2 refueling outage, all 11 Model 7657F Target Rock Two-Stage pilot valve assemblies in the SRVs were replaced with certified spares. The removed SRV pilot valves were sent to National Technical Systems (NTS) to determine the as-found set pressure. On June 5, 2017, test results were reported to BSEP. The test results showed that three of the 11 valves actuated at pressures outside of the +/-3 percent tolerance allowed by TS 3.4.3. The test data for the valves found out of tolerance are shown below:
Reportability Criteria
Event Description
Event Cause (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
CONTINUATION SHEET
Valve Identification TS Setpoint (psig) As-Found Lift Pressure (psig) Percent Difference S/N 1098 1140 1244 +9.1 S/N 1109 1130 1227 +8.6 S/N 1106 1150 1208 +5.0 APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
2017 - 003
3. LER NUMBER
- 000 Therefore, it is concluded that the SRVs always remained capable of performing their safety function of preventing overpressurization of the reactor coolant system.
Based on the foregoing analysis, it is concluded that this event had no adverse impact on nuclear safety.
Corrective Actions
All the SRV pilot assemblies were replaced with certified spares during the spring 2017, Unit 2 refueling outage.
Procedure 0CM-VSR509, “Main Steam Relief Valves Target Rock Model 7567 Air Operators and Pilot Assembly Disassembly, Inspection, and Reassembly,” has been revised to reduce the probability of have been prepared with this revised procedure.
design used at Brunswick. Brunswick mitigates corrosion bonding of SRVs by coating each pilot disc surface with platinum to prevent oxygen from interacting with the underlying Stellite. The integrity of the platinum coating is critical to mitigating corrosion bonding. In SRV pilots 1106 and 1109, the platinum coating was degraded in large areas of the pilot disc. The coating was degraded because adhesion to the underlying Stellite was not optimal. Adhesion was less than optimal because a recently devised surface preparation method (i.e., precision grinding to minimize micro-cracking) had not yet been implemented at the time these SRVs were built.
On SRV pilot 1098, extensive steam erosion changed the geometry of the pilot disc. The altered geometry required additional steam pressure to develop sufficient force to overcome the set pressure spring. The change in geometry likely resulted in wedging of the disc into the seat. Steam erosion occurred because the pilot was leaking for a significant portion of the cycle.
The purpose of the safety/relief valves is to provide overpressure protection for the reactor coolant system.
The as-found condition of the Unit 2 SRVs was analyzed per Engineering Change (EC) 409048. The analysis compares each of the 11 SRVs in its as-found condition to the most limiting case addressed in the Brunswick Unit 2 Cycle 22 Reload Safety Analysis Report (RSAR). EC 409048 shows that every SRV opened in its as-found state at a pressure lower than at least one valve in the RSAR analysis. Since each as-found SRV was bounded by the opening pressures assumed in the analysis, the overall RSAR analysis bounds the overall as-found condition of the SRVs. The peak steam dome pressure would therefore not reach the plant safety limit of 1325 psig even in the worst-case analyzed transient.
Safety Assessment (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
CONTINUATION SHEET
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
2017 - 003
3. LER NUMBER
- 000 In the past three years, two Licensee Event Reports have been submitted to the NRC describing events in which SRVs have been found with setpoint drift which made the valves inoperable.
In these events, the causes of corrosion bonding were analyzed, and corrective actions were implemented in subsequent groups of SRVs being rebuilt. However, the platinum coating process is still being advanced. Previous corrective actions could not benefit from improvements which were developed later.
This report contains no new regulatory commitments.
Commitments
Previous Similar Events
(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/) 05000325 / 2014-005, dated July 21, 2014 (ADAMS Accession Number ML14212A031) 05000324 / 2015-002, Revision 1, dated June 26, 2015 (ADAMS Accession Number ML15196A033)
CONTINUATION SHEET
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
2017 - 003
3. LER NUMBER
- 000
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05000325/LER-2017-001 | Speed and Frequency Oscillations Result in Inoperable Emergency Diesel Generator | 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000324/LER-2017-001 | Implementation of Enforcement Guidance Memorandum (EGM) 11-003, Revision 3 LER 17-001-00 for Brunswick, Unit 2, Regarding Implementation of Enforcement Guidance Memorandum (EGM) 11-003, Revision 3 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000325/LER-2017-002 | Foreign Material in Switch Results in Unplanned Automatic Start of Emergency Diesel Generators | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000324/LER-2017-002 | Plant Mode Change with Primary Containment Inoperable LER 17-002-00 for Brunswick, Unit 1, Regarding Foreign Material in Switch Results in Unplanned Automatic Start of Emergency Diesel Generators | 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000325/LER-2017-003 | Control Room Air Conditioning and Emergency Ventilation Systems Rendered Inoperable LER 17-003-00 for Brunswick, Unit 1, Regarding Control Room Air Conditioning and Emergency Ventilation Systems Rendered Inoperable | 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | 05000324/LER-2017-003 | 1 OF 4 LER 17-003-00 for Brunswick, Unit 2, Regarding Setpoint Drift in Main Steam Line Safety/Relief Valves Results in Three Valves Inoperable, | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
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