On 1/9/17, it was determined that the site's Emergency Diesel Generators do not conform with the licensing basis for protection against tornado generated missiles. The exhaust stacks for the four on-site diesel generators extend approximately seven feet above the roof of the diesel generator building. In the event of a tornado, debris generated from the tornado could strike the exhaust stacks and, if at a sufficient mass and velocity, could crimp the exhaust stacks in a manner that would affect diesel generator operation.
As a result of the non-conforming condition, on 1/9/17 at 1530, all four emergency diesel generators were declared inoperable. Compensatory measures were put in place and, in accordance with NRC guidance contained in EGM 15-002, the diesel generators were returned to an operable but non-conforming status.
This condition has been in existence since original licensing of the plant. It is not known if it was overlooked or considered acceptable at the time of the original licensing process. There are no actual consequences as a result of the non-conforming condition. |
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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, Privacy and Information Collections Branch (1--5 F53), U.S, Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to Infocollects Resource@nrc gov and to the Desk Officer Office of nformabon 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 2017 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
On January 9, 2017, based on an engineering analysis, it was determined that the site's four Emergency Diesel Generators [EIIS: DG] do not conform with the licensing basis for protection against tornado generated missiles. As a result, one or more of the diesel generators may not have been able to perform their safety design function if a tornado were to impact the site and if debris of sufficient mass and velocity were to strike the diesel engine exhaust stacks.
As a result of the non-conforming condition, on January 9, 2017, at 1530, all four emergency diesel generators were declared inoperable in accordance with Technical Specification (TS) 3.8.1. With two or more diesel generators inoperable, TS 3.8.1 Condition F requires all but one to be restored to an operable status within two hours, or per Condition G, be in Mode 3 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Compensatory measures were verified as being in place in accordance with NRC guidance contained in EGM 15-002, "Enforcement Discretion for Tornado-Generated Missile Protection Noncompliance" (ML15111A269). As allowed by the EGM, the Emergency Diesel Generators were immediately returned to an operable but non-conforming status.
EGM 15-002, along with Interim Staff Guidance DSS-ISG-2016-01, "Clarification of Licensee Actions in Receipt of Enforcement Discretion Per Enforcement Guidance Memorandum EGM 15-002" (ML15348A202), provide guidance from the NRC for acceptable compensatory measures that licensees can put in place if equipment is determined to be inoperable as a result of tornado generated missiles.
Peach Bottom's compensatory measures are in accordance with the NRC guidance. They include verification of the following:
a) Procedures are in place which instruct personnel to identify and secure potential missile hazards if severe weather is forecasted for the site.
b) Procedures require that planned maintenance of AC power sources be deferred in the event that severe weather is forecasted. Work on other equipment is controlled to minimize risk during severe weather.
c) If severe weather has occurred, procedures call for an inspection of the emergency diesel generator exhaust stacks for damage. If damage is observed and operation of the diesel engines is adversely impacted, the procedure has the damaged portion of the exhaust stack removed using a high temperature cutting torch. Two of these torches are located on site and all equipment operators have been trained on their use. They are part of the FLEX equipment that is stored in a reinforced concrete building that is designed to withstand earthquakes, tornadoes and other severe natural phenomena.
comments regarding burden estimate to the FOIA, Privacy and Information Collectors Branch (T-5 F53), 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 05000-277
3. LER NUMBER
001 0 2017 d) Increasing the level of awareness and preparedness by communicating the issue to Operations personnel though shift manager turnover notes.
Analysis of the Event
Four emergency diesel generators are located on-site which provide backup power in the event of a loss of all offsite power. Each diesel generator is rated at 2,600 kW for continuous operation at 4,160 volts.
The diesel generators provide sufficient power to safely shut down both units in the event of a design basis accident in one unit and a failure of one of the diesel generators. Each diesel generator is housed in a seismic Class I structure and designed to be protected against earthquakes, floods, tornadoes and other natural phenomena. However, the diesel engine exhaust stacks, which extend approximately seven feet above the roof of the building, are not protected against tornado generated missiles. The exhaust stacks are 24-inch diameter steel pipes with a 3/8-inch wall thickness. It was determined that, if the stacks were struck by a design basis tornado missile, they could be crimped in such a manner as to prevent the diesel generator from performing its design function. The design basis tornado missile for the site includes a wood plank that is 4 inches thick, 12 inches wide and 12 feet long traveling at 300 mph.
There were no actual consequences resulting from this non-conforming condition. A tornado that could produce the design basis missile is highly unlikely in the mid-Atlantic region. The probability of missiles causing more than one diesel generator to become inoperable is also very low.
This condition is being reported in accordance with the following criteria:
- 10CFR 50.73(a)(2)(v)(D) for any condition that could have prevented the fulfillment of the safety function of systems that are needed to mitigate the consequences of an accident.
- 10CFR 50.73(a)(2)(vii)(D) for any event where a single cause or condition caused at least two independent trains to become inoperable in a single system designed to mitigate the consequences of an accident.
Cause of the Event
This condition was part of the original plant design and has existed since the initial construction and licensing of the plant. Peach Bottom Unit 2 and Unit 3 received their operating licenses in 1973 and 1974, respectively, based in part on the design of the emergency diesel generators as described in the Final Safety Analysis Report (FSAR). This report did not address the fact that the exhaust stacks are not protected against tornado missiles and no other documented engineering analysis has been identified. It is not known if this was not evaluated at the time of the original design and licensing process, or if it was considered acceptable due to the low likelihood of damage to the exhaust stacks from tornado missiles.
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-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 va'id OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection Past perception of this condition was that only one tornado generated missile needed to be considered and only one diesel exhaust stack would be impacted. Since only three emergency diesel generators are needed to safely shut down the plant, such a condition was considered to be included in the licensing basis of the plant. Additional industry and NRC information on this issue pointed to the need to have all diesel generators survive a tornado with the capability to perform their safety function intact.
Corrective Actions
Compensatory measures were implemented in accordance with NRC guidance contained in EGM 15-002 and DSS-ISG-2016-01 as described earlier. Enforcement discretion provided by EGM 15-002 remains in effect for five years for Peach Bottom, at which time modifications, license amendments or other actions must be implemented to fully resolve the issue. Peach Bottom intends to request a license amendment to allow for probabilistic methods to be applied to demonstrate that the risk associated with tornado missiles on specific components is sufficiently small such that plant modifications are not warranted.
Previous Similar Occurrences No previous similar events have occurred at the site.