On December 6, 2017 Three Mile Island Unit 1, determined that both Emergency Diesel Generators do not conform with the licensing bases for protection against tornado generated missiles. The vent on the common Fuel Oil Supply Tank that serves both Emergency Diesel Generators could be damaged by debris generated from a tornado that could affect emergency diesel generator operation. An extent of condition review identified three additional items that are nonconforming to the design for tornado missile protection: vent stacks for each Emergency Diesel Generator Day Fuel Tanks, the Borated Water Storage Tank and steam piping near the main feed pumps that could affect Secondary Pressure Control. Upon determination of the initial nonconformance for the Fuel Oil Supply Tank Vent on December 6, 2017, both Emergency Diesel Generators were declared inoperable. Compensatory measures were put and verified in place in accordance with the NRC Enforcement Guidance Memorandum EGM 15-002, both emergency diesel generators were returned to an operable but nonconforming status and an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> ENS Notification was made to the NRC. 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 nonconforming conditions. |
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Category:Letter
MONTHYEARML24038A0222024-02-0505 February 2024 Achp Letter on Section 106 Programmatic Agreement Participation IR 05000289/20230062024-01-29029 January 2024 Constellation Energy Generation, LLC, Three Mile Island Nuclear Station, Unit 1 - NRC Inspection Report No. 05000289/2023006 ML23342A1242024-01-0909 January 2024 Independent Spent Fuel Storage Installation Security Inspection Plan ML23325A1092024-01-0505 January 2024 Review of the Management Plan for Three Mile Island Station, Unit No. 2, Debris Material ML23354A2062023-12-20020 December 2023 (TMI-2), Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation ML23354A2112023-12-20020 December 2023 Response to Request for Additional Information for the TMI-2 Post-Shutdown Decommissioning Activities Report, Rev. 5 IR 05000320/20230032023-11-28028 November 2023 TMI-2 Solutions, LLC, Three Mile Island Nuclear Station, Unit 2, NRC Inspection Report No. 05000320/2023003 ML23243A9082023-08-29029 August 2023 Shpo Letter to TMI-2 Regarding Section 106 Activities IR 05000320/20230022023-08-17017 August 2023 TMI-2 Solutions, LLC, Three Mile Island Nuclear Station, Unit 2 - NRC Inspection Report 05000320/2023002 IR 05000289/20230052023-08-14014 August 2023 Constellation Energy Generation, LLC, Three Mile Island Nuclear Station, Unit 1 - NRC Inspection Report 05000289/2023005 ML23216A1732023-08-14014 August 2023 Consultation Letter to Christine Turner for TMI-2 ML23216A1742023-08-14014 August 2023 Consultation Letter to David Morrison for TMI-2 ML23216A1752023-08-14014 August 2023 Consultation Letter to Joanna Cain for TMI-2 ML23216A1772023-08-14014 August 2023 Consultation Letter to Rebecca Countess for TMI-2 ML23216A1782023-08-14014 August 2023 Consultation Letter to Steve Letavic for TMI-2 ML23221A1402023-08-0808 August 2023 (TMI-2), Response to Requests for Additional Information for the TMI-2 Post-Shutdown Decommissioning Activities Report, Rev. 5 ML23200A1882023-07-31031 July 2023 TMI-2 Correction Letter Amendment 67 ML23209A7632023-07-28028 July 2023 Letter from PA Shpo to TMI-2 Solutions on Cultural and Historic Impacts of Decommissioning ML23192A8272023-07-10010 July 2023 TMI-2 Solutions, LLC - Response to Shpo Request for Additional Information for Er Project 2021PR03278.006, TMI-2 Decommissioning Project ML23167A4642023-07-0505 July 2023 Letter - TMI-2- Exemption 10 CFR Part 20 Append G Issuance ML23167A0312023-06-28028 June 2023 Acceptance Review and Schedule for the Request for Exemption from a Requirement from 10 CFR 20, Appendix G, Section Iii.E, EPID L-2023-LLE-0016 ML23171B0222023-06-19019 June 2023 (TMI-2) - Notification Pursuant to 10 CFR 72.140(d) Regarding Application of Previously Approved TMI-2 Quality Assurance Program to Independent Spent Fuel Storage Installation Activities ML23138A0662023-05-17017 May 2023 TMI-2 NHPA Section 106 Shpo Letter to NRC 5-17-23 ML23137A2822023-05-17017 May 2023 (TMI-2), Request for Exemption from 10 CFR 20, Appendix G, Section Iii.E ML23026A3132023-05-0202 May 2023 Issuance of Exemption from 10 CFR 70.24 (EPID-L-2023-LLE-0003) ML23121A2492023-05-0101 May 2023 License Amendment Request, Historic and Cultural Resources Review, Response to Request for Additional Information ML23122A1842023-05-0101 May 2023 Shpo_Er_Summary_Letter ML23117A0012023-04-26026 April 2023 Commitment Revision Summary Report ML23027A0832023-04-24024 April 2023 Environmental Assessment/Finding of No Significant Impact - Request for Exemption from 10 CFR 70.24 ML23108A0822023-04-18018 April 2023 Annual Radiological Environmental Operating Report ML23108A0802023-04-18018 April 2023 Annual Radiological Effluent Release Report IR 05000320/20230012023-04-12012 April 2023 TMI-2 Solutions, LLC, Three Mile Island Nuclear Station, Unit 2 - NRC Inspection Report No. 05000320/2023001 ML23108A2002023-04-10010 April 2023 CFR 20.2206(b) Personnel Radiation Exposure Report for 2022 ML23102A0382023-04-10010 April 2023 Occupational Radiation Exposure Annual Report ML23093A0602023-04-0606 April 2023 Letter to Steve Letavic, Manager, Re., Ongoing Activities Related to the Proposed License Amendment Request for Three Mile Island Nuclear Station, Unit 2 ML23094A2402023-04-0606 April 2023 Letter to Darren Bonaparte, Thpo, St. Regis Mohawk Tribe, Re., Initiation of Consultation Under Section 106 of the NHPA for the Proposed License Amendment Request for TMI 2 ML23086C0522023-04-0606 April 2023 Letter to David Morrison, Exec Dir, Historic Harrisburg Assoc Re, Ongoing Activities Related to the Proposed License Amendment Request for Three Mile Island Nuclear Station, Unit 2 ML23086C0652023-04-0606 April 2023 Ltr Larry Heady, Thpo, De. Tribe of Indian; Re., Initiation of Consultation Under Section 106 of the NHPA for the Proposed License Amendment Request for TMI Nuclear Station, Unit 2 ML23094A2352023-04-0606 April 2023 Letter to Bryan Printup, Thpo, Tuscarora Nation, Re., Initiation of Consultation Under Section 106 of the NHPA for the Proposed License Amendment Request for TMI 2 ML23086A0132023-04-0606 April 2023 Letter to Emma Dehi, PA Shpo; Re., Initiation of Consultation Under Section 106 of the NHPA for the Proposed License Amendment Request for TMI-2 ML23094A2562023-04-0606 April 2023 Letter to Tonya Tipton, Thpo, Shawnee Tribe, Re., Initiation of Consultation Under Section 106 of the NHPA for the Proposed License Amendment Request for TMI 2 ML23093A0582023-04-0606 April 2023 Letter to Christine Turner, Executive Director, Re., Ongoing Activities Related to the Proposed License Amendment Request for Three Mile Island Nuclear Station, Unit 2 ML23094A2392023-04-0606 April 2023 Letter to Courtney Gerzetich, Thpo, Onedia Nation of Wisconsin, Re., Initiation of Consultation Under Section 106 of the NHPA for the Proposed License Amendment Request for TMI 2 2024-02-05
[Table view] Category:Licensee Event Report (LER)
MONTHYEAR05000289/LER-2017-0042018-02-0505 February 2018 Items Nonconforming to Design for Tornado Missile Protection, LER 17-004-00 for Three Mile Island, Unit 1, Regarding Items Nonconforming to Design for Tornado Missile Protection 05000289/LER-2017-0032017-11-0606 November 2017 Primary Containment Declared Inoperable Due to Both Airlock Doors Open Simultaneously, LER 17-003-00 for Three Mile Island, Unit 1 Regarding Primary Containment Declared Inoperable Due to Both Airlock Doors Open Simultaneously 05000289/LER-2017-0022017-02-0606 February 2017 1 OF 5, LER 17-002-00 for Three Mile Island, Unit 1 Regarding Leak at High Pressure Connection on Reactor Coolant Pump "A" Thermal Barrier 05000289/LER-2017-0012017-02-0303 February 2017 Low Temperature Over-Pressurization (LTOP) Technical Specification Requirements Were Not Met, LER 17-001-00 for Three Mile Island Unit 1 Regarding Low Temperature Over-Pressurization (LTOP) Technical Specification Requirements Were Not Met TMI-15-062, Special Report - Radioactive Gaseous Process and Effluent Monitoring Instrumentation2015-05-0808 May 2015 Special Report - Radioactive Gaseous Process and Effluent Monitoring Instrumentation ML1012303422009-11-24024 November 2009 Decision Documentation for Reactive Inspection (Deterministic & Risk Criteria Analyzed) (Mc 0309 Enclosure 1) ML1007805012009-11-23023 November 2009 E-mail from Eric Thomas, NRR to Richard Conatser, NRR on 11/23/09 NRC Operations Center Event Report Page ML1007802702009-11-22022 November 2009 Draft Event Notice on Offsite Notification TMI 2018-02-05
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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.
3. LER NUMBER 1. FACILITY NAME 2017 004 - 00
A. EVENT DESCRIPTION
Plant Conditions before the event:
Babcock & Wilcox — Pressurized Water Reactor — 2568 MWth Core Power Date/Time: December 6, 2017 / 09:58 EST Power Level: 100% Mode: Power Operation There were no structures, systems or components (SSCs) out of service that contributed to this event.
On December 6, 2017, the plant was operating at steady state full power operation. TMI-1 was concluding a systematic review of the plant protection for tornado generated missiles against the plant design and licensing basis. It was determined that a non-conforming condition exists with the Emergency Diesel Generator (EDG) Fuel Supply Tank Vent Stack with respect to tornado missile protection. Since the fuel oil supply tank and vent stack is a common integral component of the EDG's and is not protected against tornado missiles, the design does not meet the licensing basis and a non-conforming condition exists.
TMI-1 entered this condition into the corrective action program and notified the NRC via Event Notification 53106 on December 6, 2017.
The extent of condition review identified three additional non-conforming conditions: Vent Stacks for each Emergency Diesel Generator Day Fuel Tanks, the Borated Water Storage Tank and steam piping near the main feed pumps that could affect Secondary Pressure Control. This concluded the TMI-1 evaluation of plant protection for tornado generated missiles against the plant design and licensing basis which results in the reporting of this event as a total of four (4) non-conforming conditions.
The event is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications; 10 CFR 50.73(a)(2)(ii)(B) as an event or condition that resulted in the nuclear power plant being in an unanalyzed condition that significantly degraded plant safety; 10 CFR 50.73(a)(2)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident; 10 CFR 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.
B. CAUSE OF EVENT
These conditions were part of the original plant design and have existed since the initial construction and licensing of the plant. TMI-1 received its operating license on September 19, 1974, based in part on the design as described in the Final Safety Analysis Report (FSAR). The NRC (at that time the Atomic Energy Commission, AEC) issued its safety evaluation for TMI-1 on July 11, 1973. It is not known whether these 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.
3. LER NUMBER 1. FACILITY NAME 2017 004 00 recently identified non-conforming SSCs were considered acceptable due to the low likelihood of damage to the SSCs from tornado-generated missiles during the time of the original design and licensing process.
TMI-1 identified four SSCs as non-conforming conditions to the plant design and licensing basis because of and in concert with a collective industry effort to address the NRC issuance of Regulatory Issue Summary 2015-06 "Tornado Missile Protection".
C. ANALYSIS / SAFETY SIGNIFICANCE
There were no actual consequences resulting from these identified non-conforming conditions. A tornado that could produce the design basis missile is highly unlikely in the mid-Atlantic region. The probability of missiles striking any one of the identified non-conforming SSCs in a fashion to render the SSC inoperable is also very low.
The TMI-1 FSAR described characteristics of the design basis tornado (DBT) wind hazard and tornado generated missile hazard, design requirements are stated as:
- Tangential wind velocity of 300 mph. (A gust factor of 1.3 has been used for those structures designed for tornado loadings.)
- An external vacuum of 3 psig.
- Missile equivalent to a utility pole 35 foot long, 14 inches in diameter, weighing 50 pounds per cubic foot, and traveling at 150 mph.
- Missile equivalent to a 1 ton automobile traveling at grade at 150 mph.
TMI-1 reviewed these requirements against the plant SSCs needed to achieve safe shutdown in the event of a tornado. The result was the identification of four non-conforming conditions described in the event description which were declared inoperable.
NRC Enforcement Guidance Memorandum EGM 15-002, Revision 1, provides for application of NRC enforcement discretion which allows the four identified non-conforming conditions to be returned to an operable status based on the application of compensatory measures which are intended to reduce the likelihood that the tornado event would result in a failure of any one of the identified non-conforming conditions. TMI-1 applied the guidance in EGM 15-002, Revision 1, and, NRC DSS-ISG-2016-01 Revision 1 Appendix A, to determine the acceptable initial and comprehensive compensatory measures necessary to ensure that the identified nonconforming condition could be treated by the NRC with enforcement discretion.
D. CORRECTIVE ACTIONS
Compensatory measures were implemented in accordance with NRC guidance contained in the EGM 15- 002 (revision 1) and DSS-ISG-2016-01 (revision 1) as described earlier. Enforcement discretion provided by EGM 15-002 remains in effect until June 10, 2020, for TMI-1, at which time modifications, license amendments or other actions must be implemented to fully resolve the issue. TMI-1 intends to request a 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.
3. LER NUMBER 1. FACILITY NAME 2017 004 - 00 license amendment to allow for probabilistic methods to be applied to demonstrate that the risk associated with tornado generated missiles on specific components is sufficiently small such that plant modifications are not warranted.
E. PREVIOUS OCCURENCES
No previous similar events have occurred at the site.