05000373/LER-2018-001, Unanalyzed Condition Affecting Accident Mitigation for Tornado Generated Missile Protection Non-Conformances

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Unanalyzed Condition Affecting Accident Mitigation for Tornado Generated Missile Protection Non-Conformances
ML18106A105
Person / Time
Site: LaSalle  
(NPF-011, NPF-018)
Issue date: 04/16/2018
From: Vinyard H
Exelon Generation Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
RA18-024 LER 2018-001-00
Download: ML18106A105 (6)
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LER-2018-001, Unanalyzed Condition Affecting Accident Mitigation for Tornado Generated Missile Protection Non-Conformances
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
10 CFR 50.73(a)(2)(ix)(A)
10 CFR 50.73(a)(2)(viii)(A)
10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat
10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown
10 CFR 50.73(a)(2)(i)
3732018001R00 - NRC Website
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text

Exelon Generation LaSalle County Station 2601 North 21 1 Road Marseilles, IL 61341 815-415-2000 Telephone www.exeloncorp.com 10 CFR 50.73 RA18-024 April 16, 2018 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

LaSalle County Station, Unit 1 and Unit 2 Renewed Facility Operating Licenses No. NPF-11 and NPF-18 NRG Docket No. 50-373 and No. 50-374 Licensee Event Report 2018-001-00, Unanalyzed Condition Affecting Accident Mitigation for Tornado Generated Missile Protection Non-Conf ormances In accordance with 1 O CFR 50.73(a)(2)(i)(B), 1 O CFR 50.73(a)(2)(ii)(B), 1 O CFR 50.73(a)(2)(v)(D), 1 O CFR 50.73(a)(2)(vii), and 1 O CFR 50.73(a)(2)(ix)(A), Exelon Generation Company, LLC (EGG) is submitting Licensee Event Report (LEA)

Number 2018-001-00 for LaSalle County Station, Unit 1 and Unit 2.

There are no regulatory commitments in this letter. Should you have any questions concerning this report, please contact Mr. Guy V. Ford, Jr., Regulatory Assurance Manager, at (815) 415-2800.

I7J~

Harold T. Vinyard Plant Manager LaSalle County Station

Enclosure:

Licensee Event Report cc:

Regional Administrator - NRG Region Ill NRG Senior Resident Inspector-LaSalle County Station

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 (02-2018)

Estinated bunlen per response to comply wifl this mandatory collection request: BO hours

,.....~ **c~,

LICENSEE EVENT REPORT (LER)

Reported lessons learned are incorporated into the li:ensing process and led back to i'lduslly

~~

Send comments regardi'lg burden estinate to the lnfonrati:m Services Branch

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(See Page 2 for required number of digits/characters for each block)

(H F43), U.S. Nuclear Regulatory Co!M'issioo, Washington, DC 20555-0001, Of by e*mal h

to lnfocollecls.Resoun:e@nrc.gov, and to Ile Desk Offi::er, Olli:e of Information ard 0

\\~ i (See NUREG-1022, R.3 for instruction and guidance for completing this fomn Regulatory Affaits, NEOB-10202, (31S<Hl104), Office of Management and Budget, Washington, DC 20503 tt e means used to ~se an information colection does not

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http://www.nrc.gov/reading-rm/doc-colleclions/nu regs/slall/sr1 022/r3D dlSpiay a culTI!fltly vali:l OMB control nunt>er, Ille NRC may not conduct Of sponSOf, and a person is not required to respond to, the information coRection.

3.Page LaSalle County Station, Unit 1 05000373 1

OF 5

4. Title Unanalyzed Condition Affecting Accident Mitigation for Tornado Generated Missile Protection Non-Conformances
5. Event Date
6. LEA Number
7. Report Date
8. Other Facilities Involved I

Sequential I Rev Facility Name Docket Number Month Day Year Year Number No.

Month Day Year LaSalle County Station, Unit 2 05000374 Facility Name Docket Number 02 15 18 2018 - 001 00 04 16 18 NA NA

9. Operating Mode
11. This Report is Submitted Pursuant to the Requirements of 10 CFR §: (Check all that apply)

D 20.2201(b)

D 20.2203(a)(3)(i)

D 50. 73(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(A)

D 20.2201(d)

D 20.2203(a)(3)(ii)

[81 50.73(a)(2)(ii)(B)

D 50. 73(a)(2)(viii)(B) 1 D

D D 50.1s(a)(2)(iiil [81 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(ix)(A)

D 20.2203(a)(2)(i)

D 50.36(c)(1 )(i)(A)

D 50.73(a)(2)(iv)(A)

D 50. 73(a)(2)(x)

10. Power Level D 20.2203(a)(2)(ii)

D 50.36(c)(1 )(ii)(A)

D 50. 73(a)(2)(v)(A)

D 13.11 (a)(4l D 20.2203(a)(2)(iii)

D 50.36(c)(2)

D 50.73(a)(2)(v)(B)

D 13.11 (a)(s)

D 20.2203(a)(2)(iv)

D 50.46(a)(3)(ii)

D 50. 73(a)(2)(v)(C)

D 13.11(a)(1J 95 D 20.2203(a)(2)(v)

D 50.73(a)(2)(i)(A)

[81 50.73(a)(2)(v)(D)

D 1s.11(a)(2)(iil D 20.2203(a)(2)(vi)

~ 50.73(a)(2)(i)(B)

[81 50.73(a)(2)(vii)

D 1s.11(a)(2)(iiil D 50.73(a)(2)(i)(C)

D Other (Specify in Abstract below or in This condition is reportable as a licensee event report (LER) in accordance with:

SEQUENTIAL NUMBER 001 REV NO.

00 1 OCFR 50.73(a)(2)(i)(B) for operation or condition prohibited by TS, since the design deficiency (i.e., non-conforming condition) exited for a time longer than permitted by TS; 1 OCFR 50. 73(a)(2)(ii)(B) for an unanalyzed condition that significantly degraded plant safety; 1 OCFR 50. 73(a)(2)(v)(D) for an event or condition that would have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident since the VG and VE system are part of the habitability environment for operators used in response to a postulated radioactive release; 10CFR 50.73(a)(2)(vii) for a single event that affected multiple trains in a single system used to mitigate the consequences of an accident since the design deficiency affected both trains of VG and both trains of VE; and, 1 OCFR 50. 73(a)(2)(ix)(A) for an event or condition that affected two or more trains in different systems used to mitigate the consequences of an accident since the design deficiency affected both VG and VE systems, as well as Unit 2 Division 2 systems supported by 480V MCC 236X-1.

Current Licensing Basis (CLB) Review The affected SSCs are required for Tornado Safe Shutdown (TSS) but are not protected against tornado missiles as required to meet the CLB. The LSCS CLB for tornados and tornado missiles pertinent to RIS 2015-06 are described in Updated Final Safety Analysis Report (UFSAR). The original plant licensing documents were reviewed to determine licensing requirements that are not specifically detailed in the LSCS UFSAR. The additional documents which were reviewed include the original Standard Review Plan (NUREG-0800), Safety Evaluation Report (NUREG-0519), FSAR, FSAR Questions and Answers applicable to tornados and tornado missile protection, and the General Design Criteria (GOG).

The design basis tornado has a maximum rotational velocity of 300 miles per hour (mph), a translational velocity of 60 mph, causes a pressure drop of 3 pounds per square inch (psi) at the vortex in three seconds, and a radius of maximum wind speed of 227 feet.

The CLB for tornado missile protection design involves two types of missiles which have been considered. They are a wood plank of 4 inches by 12 inches by 12 feet dimension with an impact velocity of 225 mph; and a 4,000-pound automobile with a 20-square foot front area and a 50-mph impact velocity. Station personnel reviewed these requirements against the plant SSCs needed to achieve safe shutdown in the event of a tornado. The result was the identification of non-conforming conditions described above in the event description.

Operability Discussion Due to the identified vulnerabilities from a tornado missile, both trains of the MGR and the AEER Control Room Area Filtration systems, the Control Room Area Ventilation Air Condition Systems, and Unit 2 MCC 236X-1 were declared inoperable. For both Unit 1 and Unit 2, the station entered TS 3.7.4 Required Actions A.1 and E.1 and TS 3.7.5 Required Actions A.1 and B.1. Although the probability of loss of function is low, it is possible that tornado missiles could impact the MGR and/or the AEER ventilation systems, resulting in loss of the TS 3.7.4 and or 3.7.5 safety function for both trains of VG and/or VE.

Division 2 480V MCC 236X-1 being inoperable resulted in the following equipment fed from the MCC also being INOPERABLE which includes U2 SBGT, U2 Division 2 Post LOCA, B MGR Control Room Area Filtration system supply and exhaust fan, Reactor Building Division 2 isolation Dampers 2VR04YB and 2VR05YA control logic, 2VQ037 damper, Unit 2 Division 2 battery room exhaust fan and Unit 2 24/48 Volt battery rooms exhaust fans. The station entered TS 3.8.7 Required Action A.1 for Loss of 236X-1 Power Distribution Subsystem for Unit 2, TS 3.8. 7 Required Action D.1 for Loss of 236X-1 Power Distribution Subsystem for Unit 1, TS 3.7.4 Required Action A.1 for the B MGR and the AEER Control Room Area Filtration systems, previously entered for both units, TS 3.6.4.3 Required Action A.1 for Unit 2 SBGT for both units, and TS 3.6.4.2 Required Actions A.1 and A.2 for 2VQ037 and Dampers 2VR04YB and 2VR05YA both units. lnoperability of battery room fans for U-2 Division 2 and 24/48 Volt batteries is addressed under guidance in LOP-VX-02 without affecting operability of the associated DC systems.

Based on the tornado analysis, the MCA and AEER ventilation systems and U-2 Division 2 480V MCC 236X-1 and respective equipment listed above were inoperable, with the applicable TSs immediately exited per allowance of EGM 15-002, Revision 1, that states the listed tornado vulnerable equipment is considered operable, but non-conforming. LSCS exited TS 3.7.4 Required Actions and TS 3.7.5 Required Actions for the MCA and the AEER Control Room Area Filtration systems and the Control Room Area Ventilation Air Condition systems, TS 3.8.7 Electrical Distribution Systems, TS 3.6.4.3 Standby Gas Treatment System, and TS 3.6.4.2 Secondary Containment Isolation Valves. The battery room fans for U-2 Division 2 and 24/48 volt batteries were also considered operable but non-conforming. This EGM applies to a SSC that is determined to be inoperable for tornado generated missile protection. In addition, Interim Staff Guidance DSS-ISG-2016-01, Revision 1, "Clarification of Licensee Actions in Receipt of Enforcement Discretion per Enforcement Guidance Memorandum EGM 15-002," provides clarification for requirements to be met to allow enforcement discretion. In accordance with Appendix A, Clarification of Actions in EGM 15-002, Revision 1, initial compensatory actions have been established that provide additional protection such that the tornado missile effects are lessened.

Application of EGM 15-002 Application of the guidance in EGM 15-002, Revision 1, and, NRC DSS-ISG-2016-01, Revision 1, Appendix A, describes acceptable initial and comprehensive compensatory measures necessary to ensure that the identified nonconforming conditions can be treated by the NRC with enforcement discretion. The non-conforming conditions will require resolution prior to the end of the enforcement discretion period, which is June 10, 2018 since LSCS is classified as a "Group A" (Higher Tornado Missile Risk) plant.

LSCS applied the guidance in EGM 15-002, Revision 1, and NAC DSS-ISG-2016-01, Revision 1, Appendix A, to determine the acceptable initial and comprehensive compensatory measures necessary to ensure that the identified non-conforming conditions could be treated by the NRC with enforcement discretion.

Subsequently, in accordance with the EGM 15-002, Revision 1, a request to extend the expiration date for the period of enforcement discretion for LSCS from June 10, 2018 to June 10, 2020 was submitted to the NAC on March 20, 2018. The requested enforcement discretion expiration date of June 10, 2020 would allow sufficient time to resolve the tornado missile protection non-conformances and restore the site to compliance. Resolution of the non-conforming conditions is expected to involve a combination of analysis and potentially plant modification installations.

CORRECTIVE ACTIONS

This condition is being addressed in accordance with NRC enforcement guidance provided in EGM 15-002, Revision 1 and DSS-ISG-2016-01, Revision 1. Enforcement discretion provided by EGM 15-002, Revision 1 remains in effect until June 10, 2018, for LSCS, at which time modifications, license amendments, or other actions must be implemented to fully resolve the issue.

Compensatory measures have been implemented in accordance with these documents.

Initial compensatory measures were established by an Operations Standing Order in accordance with NRC DSS-ISG-2016-0 Revision 1, Appendix A regarding:

1.

Procedures were verified to be put in place, with associated current training, for performing actions in response to a tornado.

2.

Procedures were verified to be put in place, with associated current training, for actions to be taken if a tornado watch is issued for the area.

3.

Procedures were verified to be put in place, with associated current training, for actions to be taken if a tornado warning is issued for the area.

4.

Established a heightened level of station awareness and preparedness relative to identified tornado missile vulnerabilities.

The comprehensive compensatory measures were established by incorporating the Standing Order actions and adding additional detail to Operations procedure LOA-TOAN-001, Revision 22, "High Winds I Tornado," for completing additional inspections and restoration actions on equipment vulnerable to tornado missile damage. The procedure directs operators to inspect VCNE and 236X-1 for damage after high wind conditions are clear. If VCNE and/or 236X-1 experience damage during the high wind event, operators are directed to perform additional response actions delineated in the LOA-TORN-001, Revision 22 procedure's attachments. These actions are not time-critical actions and can easily be performed in conjunction with other actions.

SEQUENTIAL NUMBER 001 REV NO.

00 Additionally, in accordance with the EGM 15-002, Revision 1, a request to extend the expiration date for the period of enforcement discretion for LSCS to June 10, 2020 was submitted to the NRC on March 20, 2018. The requested enforcement discretion expiration date would allow time to resolve the tornado missile protection non-conformances and restore the site to compliance.

PREVIOUS OCCURRENCES

There have been no similar events or conditions at the station in the previous three years.

COMPONENT FAILURE DATA

Manufacturer: NA Device: NA Component ID: Model NA Page _s_ of _s_

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