On 9/12/16, an engineering evaluation concluded that a flaw identified on a 1" diameter stainless steel pipe associated with the High Pressure Service Water ( HPSW) System could have failed during a seismic event.
Failure of the pipe would cause flooding of the '2C' Residual Heat Removal (RHR) pump room and impact operation of equipment in the room if needed during a design basis event. The 1" diameter pipe supplies sample water to the '2C' HPSW radiation monitor sample pump. The flaw was identified on 8/16/16 when a 120 drop per minute leak was observed. The leak was the result of a crack located in the pipe at the toe of a fillet weld connecting the pipe to a coupling on an 18" diameter pipe that returns HPSW water to the plant discharge canal.
There were no actual consequences as a result of the leak. The pipe was replaced and the equipment was returned to service. |
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Category:Letter
MONTHYEARML24022A2262024-01-22022 January 2024 (PBAPS) Unit 3 - Submittal of the Inservice Inspection (ISI) Owner'S Activity Report (OAR) for the 24th Refueling Outage for Unit 3 ML23346A2412024-01-17017 January 2024 Staff Assessment of Updated Seismic Hazards Following the NRC Process for the Ongoing Assessment of Natural Hazards Information (EPID L-2019-PMP-0061) - Letter IR 05000277/20234022024-01-11011 January 2024 Security Baseline Inspection Report 05000277/2023402 and 05000278/2023402 and Independent Spent Fuel Storage Installation Security Inspection 07200029/2023401 ML23354A1922024-01-0505 January 2024 Exemption from Select Requirements of 10 CFR Part 73 (Security Notifications, Reports, and Recordkeeping and Suspicious Activity Reporting) ML23355A0622023-12-18018 December 2023 Independent Spent Fuel Storage Installation (Isfsi), Security Plan, Training and Qualification Plan, and Safeguards Contingency Plan ML23278A1292023-12-14014 December 2023 Units 1 & 2; Limerick, Units 1 & 2; Nine Mile Point, Units 1 & 2; and Peach Bottom, Units 2 & 3 -Revision to Approved Alternatives to Use Boiling Water Reactor Vessel and Internals Project Guidelines ML23305A1402023-12-13013 December 2023 Units 1 & 2; Nine Mile Point, Unit 2; Peach Bottom, Units 2 & 3; and Quad Cities, Units 1 and 2 - Issuance of Amendments to Adopt Traveler TSTF-580 ML23334A2502023-11-30030 November 2023 Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation ML23270C0072023-11-29029 November 2023 Notice of Proposed Amendment to Decommissioning Trust Agreement ML23317A1192023-11-10010 November 2023 Constellation Energy Generation, LLC - 2023 Annual Report - Guarantees of Payment of Deferred Premiums ML23305A3472023-11-0101 November 2023 Revision of One Form That Implements the Radiological Emergency Response Plan (RERP) IR 05000277/20230032023-10-30030 October 2023 Integrated Inspection Report 05000277/2023003 and 05000278/2023003 and Exercise of Enforcement Discretion ML23286A0012023-10-13013 October 2023 Reply to a Notice of Violation (NOV) - NOV 05000277, 05000278/2023010-01 RS-23-097, Constellation Energy Generation, LLC, Advisement of Leadership Changes and Submittal of Updated Standard Practice Procedures Plans2023-10-12012 October 2023 Constellation Energy Generation, LLC, Advisement of Leadership Changes and Submittal of Updated Standard Practice Procedures Plans ML23271A1342023-10-11011 October 2023 Dtf Analysis Letter IR 05000277/20244012023-10-0505 October 2023 Information Request for the Cybersecurity Baseline Inspection, Notification to Perform Inspection 05000277/2024401 and 05000278/2024401 ML23265A1502023-09-22022 September 2023 License Amendment Request Revise a License Condition and Certain Technical Specifications to Remove Restrictions in Support of Decommissioning Activities ML23264A8682023-09-21021 September 2023 Independent Spent Fuel Storage Installation Registration of Dry Storage Canister WC-EOS-37PTH-008-B4L, WC-EOS-37PTH-007-B4L, and WC-EOS-37PTH-002-B4L IR 05000277/20230102023-09-15015 September 2023 Biennial Problem Identification and Resolution Inspection Report 05000277/2023010 and 05000278/2023010 and Notice of Violation ML23251A2022023-09-11011 September 2023 Cover Letter W/Report LR-N23-0045, and Peach Bottom Atomic Power Station, Units 2 and 3 - Notice of Proposed Amendment to Decommissioning Trust Agreement2023-09-0808 September 2023 and Peach Bottom Atomic Power Station, Units 2 and 3 - Notice of Proposed Amendment to Decommissioning Trust Agreement IR 05000277/20230052023-08-31031 August 2023 Updated Inspection Plan for Peach Bottom Atomic Power Station, Units 2 and 3 (Report 05000277/2023005 and 05000278/2023005) ML23158A1952023-08-30030 August 2023 R. E. Ginna - Issuance of Amendments to Adopt TSTF-273-A, Revision 2, Safety Function Determination Program Clarifications ML23232A0012023-08-19019 August 2023 Revision of One Procedure That Implements the Radiological Emergency Response Plan (Rerp). Includes EPP 06-009, Rev. 13 IR 05000277/20230112023-08-15015 August 2023 Comprehensive Engineering Team Inspection Report 05000277/2023011 and 05000278/2023011 ML23226A1112023-08-14014 August 2023 10 CFR 50.46 Annual Report IR 05000277/20230022023-08-0808 August 2023 Integrated Inspection Report 05000277/2023002 and 05000278/2023002 RS-23-087, Revision to Approved Alternatives Associated with the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor2023-08-0404 August 2023 Revision to Approved Alternatives Associated with the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor IR 05000277/20230402023-07-17017 July 2023 95001 Inspection Supplemental Report 05000277/2023040 and Follow-Up Assessment Letter ML23188A0532023-07-0707 July 2023 Registration of Use of Independent Spent Fuel Storage Installation (ISFSI) Casks ML23186A1272023-07-0606 July 2023 Response to Disputed Non-Cited Violation Documented in Peach Bottom Atomic Power Station, Units 2 and 3, Inspection Report 05000277/2022004 and 05000278/2022004 ML23178A0352023-06-27027 June 2023 Senior Reactor and Reactor Operator Initial License Examinations RS-23-077, Response to NRC Regulatory Issue Summary 2023-01, Preparation and Scheduling of Operator Licensing Examinations2023-06-16016 June 2023 Response to NRC Regulatory Issue Summary 2023-01, Preparation and Scheduling of Operator Licensing Examinations ML23151A4162023-05-31031 May 2023 Revision of One Form That Implements the Radiological Emergency Response Plan (RERP) for Wolf Creek Generating Station (WCGS) ML23150A2052023-05-30030 May 2023 Independent Spent Fuel Storage Installation (Isfsi), Annual Radiological Environmental Operating Report 80 January 1, 2022 Through December 31, 2022 RS-23-042, Application to Revise Technical Specifications to Adopt TSTF-580, Provide Exception from Entering Mode 4 with No Operable RHR Shutdown Cooling2023-05-25025 May 2023 Application to Revise Technical Specifications to Adopt TSTF-580, Provide Exception from Entering Mode 4 with No Operable RHR Shutdown Cooling ML23142A1602023-05-23023 May 2023 Summary of April 11, 2023, Public Observation Meeting with Constellation Energy Generation, LLC Re Proposed Exemption Request from Work Hour Requirements ML23132A1582023-05-18018 May 2023 Correction to Technical Specification 3.4.7 (Page 3.4-16) Issued in Amendment No. 337 ML23132A1532023-05-12012 May 2023 Transmittal of 2022 Annual Financial Reports WM 23-0009, Financial Assurance Requirements for Decommissioning Nuclear Power Reactors 10 CFR 50.75(f)(1)2023-05-10010 May 2023 Financial Assurance Requirements for Decommissioning Nuclear Power Reactors 10 CFR 50.75(f)(1) IR 05000277/20230012023-05-0808 May 2023 Integrated Inspection Report 05000277/2023001 and 05000278/2023001 ML23114A2522023-04-28028 April 2023 Request to Use a Provision of a Later Edition of the ASME Boiler & Pressure Vessel Code, Section XI 2024-01-05
[Table view] Category:Licensee Event Report (LER)
MONTHYEARML21196A4852021-07-16016 July 2021 LER 2-2021-002-00 for Peach Bottom Atomic Power Station, Unit 2, Safety Relief Valve Inoperability Due to Nitrogen Leakage from Braided Hose Wear 05000278/LER-2017-0012017-12-20020 December 2017 Reactor Pressure Boundary Leakage Due to Weld Failure in One-Inch Diameter Instrument Line, LER 17-001-00 for Peach Bottom Atomic Power Station (PBAPS), Unit 3 Regarding Reactor Pressure Boundary Leakage Due to Weld Failure in One-Inch Diameter Instrument Line 05000277/LER-2017-0012017-03-0808 March 2017 Emergency Diesel Generator Exhaust Stacks Nonconforming Design for Tornado Missile Protection, LER 17-001-00 for Peach Bottom Atomic Power Station (PBAPS), Unit 2 Regarding Emergency Diesel Generator Exhaust Stacks Nonconforming Design for Tornado Missile Protection 05000278/LER-2016-0012016-11-22022 November 2016 Leak in High Pressure Coolant Injection Drain Pipe Results in a Loss of Safety Function, LER 16-001-00 for Peach Bottom, Unit 3, Regarding Leak in High Pressure Coolant Injection Drain Pipe Results in a Loss of Safety Function 05000277/LER-2016-0012016-11-11011 November 2016 Leak in High Pressure Service Water Pipe Results in Condition Prohibited by Technical Specifications, LER 16-001-00 for Peach Bottom, Unit 2, Regarding Leak in High Pressure Service Water Pipe Results in Condition Prohibited by Technical Specifications 05000278/LER-2015-0012016-02-26026 February 2016 Loss of High Pressure Coolant Injection System Function as a Result of Failed Flow Controller Signal Converter, LER 15-001-00 for Peach Bottom, Unit 3, Regarding Loss of High Pressure Coolant Injection System Function as a Result of Failed Flow Controller Signal Converter ML13058A0432013-02-22022 February 2013 Submittal of Independent Spent Fuel Storage Installation (ISFSI) Cask Event Report ML1007702362010-03-12012 March 2010 60-Day Security Event Report 2-10-S01 ML0927401622009-09-30030 September 2009 LER 09-S01-00 for Peach Bottom, Units 2 & 3 Regarding Unescorted Access Granted to Contract Worker Who Did Not Provide Complete Work History Information ML1015505682009-07-10010 July 2009 Event Notification for Peach Bottom on Elevated Tritium Levels Found in On-Site Well ML0434503772004-12-10010 December 2004 LER-04-S01-00 for Peach Bottom Atomic Power Station (PBAPS) Unit 2 and Unit 3, 60 Day Security Event Report 2-04-S01 ML19095A7391976-12-0505 December 1976 Reporting Abnormal Occurrence No. 50-278-74-33 at Peach Bottom Atomic Power Station for Failure of Main Steam Line High Flow Switch dPIS-3-2-116C to Trip During Surveillance Test 2021-07-16
[Table view] |
comments regarding burden estimate to the FOIA, Pnvacy and Information Col ections Branch
- T 5 F53), U.S Nuclear Regulatory Commission, Washington, DC 20555-0001 or by e ma 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.
05000-277
3. LER NUMBER
001 0 2016 Unit Conditions Prior to the Event Unit 2 and Unit 3 were both operating in Mode 1 at approximately 100% rated thermal power. There were no structures, systems or components out of service that contributed to this event.
Description of Event
The High Pressure Service Water (HPSW) system (EIIS: BI) is a safety-related system that provides cooling water to four heat exchangers in the Residual Heat Removal (RHR) system (EIIS: BO) during post-accident conditions. The HPSW system consists of four 4,500 gpm pumps that normally draw water from the Conowingo Pond. The system can also be lined up to draw water from the Emergency Cooling Tower (ECT) (EIIS: BS) in the event that suction from the pond becomes unavailable. Water is pumped to the RHR heat exchangers, each of which is located in a watertight room. Water exits the heat exchangers through 14" diameter pipes. Those pipes from the 'A' and 'C' heat exchangers combine into an 18" diameter line, which later combines with an 18" diameter line from the 'B' and 'D' heat exchanger into a 24" diameter line that goes to the plant discharge canal. On the 18" diameter return line from the 'A' and 'C' heat exchangers, there is a pipe connection for a line to the HPSW radiation monitor sample pump.
The line is a 1" diameter Schedule 40S (0.133" wall thickness) Type 304 stainless steel pipe that was installed as part of a 1994 modification. The line is connected to the 18" diameter HPSW line with a socket weld connection to a half-coupling. The 1" pipe has a short span from the half-coupling to a rigid support on the wall, with two small valves in the span.
On 8/16/16, at approximately 0830 hours0.00961 days <br />0.231 hours <br />0.00137 weeks <br />3.15815e-4 months <br />, in PBAPS Unit 2, a 120 drop per minute leak was identified on the 1" pipe to the '2C' HPSW radiation monitor sample pump. Inspection determined that the leak was from a crack in the pipe located at the toe of the weld to the half-coupling on the 18" diameter HPSW return line from the 'A' and 'C' RHR heat exchangers. The crack was approximately 1" long and located between the 11:00 o'clock and 2:00 o'clock positions on the pipe.
Due to the length of the crack, the structural integrity of the pipe was questionable. If the pipe were to shear at the crack location, it was estimated that 77 gpm would flow through the opening into the 'C' RHR room. As a result of the identified condition, the following equipment was declared inoperable at 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> on 8/16/16:
- One low pressure ECCS injection subsystem per TS 3.5.1.A due to flooding potential in the 'C' RHR room
- One RHR suppression pool cooling subsystem per TS 3.6.2.3.A due to flooding potential in the 'C' RHR room
- One RHR suppression pool spray subsystem per TS 3.6.2.4.A due to flooding potential in the 'C' RHR room
- One RHR drywell spray subsystem per TS 3.6.2.5.A due to flooding potential in the 'C' RHR room
- One HPSW subsystem per TS 3.7.1.A due to through-wall leak in ASME Class 3 piping 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 e-ma 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 X 20503. If a means used to impose an 'nformation co lection does not display a currently valid OMB control number, the NRC may nut conduct or sponsor, and a person is not requ'red to respond to, the information collection.
05000-277
3. LER NUMBER
2016 0 001
- The emergency heat sink per TS 3.7.3.6 due to potential for loss of inventory (applies to both Units 2 and 3) The pipe was replaced and the affected equipment was restored to an operable status on 8/18/16 at 0610 hours0.00706 days <br />0.169 hours <br />0.00101 weeks <br />2.32105e-4 months <br />. The elapsed time from the discovery of the failure to when the equipment was returned to service was approximately 45 hours5.208333e-4 days <br />0.0125 hours <br />7.440476e-5 weeks <br />1.71225e-5 months <br /> and 40 minutes.
Analysis of the Event
Initial evaluation of the flaw could not determine if the pipe would have failed during a seismic event.
More detailed modeling of the pipe from its connection on the 18" diameter HPSW line to the first anchor point on the wall determined that seismic stresses could have caused the crack to propagate and result in a complete fracture of the pipe. This conclusion was reached on 9/12/16 and is considered to be the time at which a reportable event was identified. It is unknown at what time the crack developed into the as- found condition, however it is likely that it existed for a period of time greater than the TS required completion time for the systems to be restored to an operable status (7 days for each condition). Since the condition existed for a period of time longer than the TS required completion time, the condition resulted in a condition prohibited by TS and is being reported pursuant to 10CFR 50.73(a)(2)(i)(B).
Cause of the Event
To determine the cause of the crack, the section of the pipe and the socket weld were sent to an off-site lab for failure analysis. The cracking initiated at the toe of the weld on the outer diameter of the pipe and propagated in one general direction through the pipe wall. The fracture surface was examined by scanning electron microscopy and had transgranular features which are typical of fatigue. There were no material anomalies at the fracture origins and the weld appeared to be of generally good quality. The analysis concluded that the leak was caused by fatigue cracking caused by cyclic loading conditions, such as vibration.
The pipe was anchored to the wall a short distance from its connection to the 18" diameter HPSW line.
This design did not adequately account for vibration in the HPSW line, which resulted in bending stresses in the 1" pipe at the toe of the fillet weld connection to the half coupling. In addition, a 2:1 weld was not used with the socket weld. The current standard for fillet welds on small bore piping subject to vibration is to use a weld with a length to depth ratio of 2:1 in order to mitigate stress from vibration. A contributing cause is that the pipe appeared to have been slightly distorted in the downward direction.
Corrective Actions
The pipe was replaced between the 18" HPSW pipe and the first valve. A 2:1 weld was utilized at the socket to mitigate vibration impacts. The configuration of the 1" pipe is used at a total of 16 locations at the plant for the supply and return lines for radiation monitors for the HPSW system. All were visually inspected to determine if similar flaws existed on the other lines. No flaws were identified. Non- comments regarding burden estimate to the FOIA, Pnvacy and Information Collecfions Branch (T-5 F53), U S Nuc'ear Regulatory Commission Washington. DC 20555-0001, or by e-mail to Infocollects Resource@nrc gov and to the Desk Officer, Office of Information and Regulatory Affairs, 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.
05000-277
3. LER NUMBER
001 0 2016 destructive examinations have been scheduled to obtain additional information on the condition of the piping.
Previous Similar Occurrences Since the modification in 1994 that installed the radiation monitors and associated piping, there have been no other documented cases of leakage from this piping.