05000321/LER-2018-001, Regarding Condition Prohibited by Tech Specs Due to Secondary Containment Inoperability

Regarding Condition Prohibited by Tech Specs Due to Secondary Containment Inoperability

ML18080A054
Person / Time
Site:	Hatch
Issue date:	03/21/2018
From:	Vineyard D Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-18-0350 LER 2018-001-00
Download: ML18080A054 (5)

LER-2018-001, Regarding Condition Prohibited by Tech Specs Due to Secondary Containment Inoperability

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3212018001R00 - NRC Website

text

f. Southern Nuclear March 21, 2018 Docket Nos.: 50-321 50-366 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Davdd R. V"ID.f3rd Va Pliasil!atill A!n1 HC:h H8b:h Nudear Plaid 11028 Ha:l:h PaJD;ay N!ll:h Baxley, GA 31513 912 537 5859 tal 912 366 2071 lax NL-18-Q350 Edwin I. Hatch Nuclear Plant Unit 1 and 2 Condition Prohibited by Tech Specs Due to Secondary Containment lnoperability Ladies and Gentlemen:

In accordance with the requirements of 10 CFR 50. 73(a}(2}(i)(B) and 10 CFR 50.73(a}(2)(v)(C), Southern Nuclear Operating Company (SNC) hereby submits the enclosed Licensee Event Report (LER).

This letter contains no NRC commitments. If you have any questions, please contact Keith Long at (912) 537-5874.

Respectfully submitted, D. R. Vineyard Vice President - Hatch DRV!jcb Enclosure: LEA 2018-001-00

U. S. Nuclear Regulatory Commission NL-18-0350 Page2 Cc:

Regional Administrator, Region II NRR Project Manager-Hatch Senior Resident Inspector-Hatch RTYPE: CHA02.004

NRC FORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMS: NO. 3150*0104 EXPIRES: 10/31/2018 (06-2016)

Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.

f~

LICENSEE EVENT REPORT (LER)

Reported lessons learned are incorporated into the licensing process and led back to industry.

Send comments regarding burden estimate to the FOIA, Privacy and lnfomnation Collections

~--')'

(See Page 2 for required number of di~characters for each block)

Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of lnfomnation and Regulatory (See NUREG-1 022, R.3 for instruction and guidance for completing this form Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an infomnation collection does not display a currently valid OMB control ltlttn:/tww.v.nre.~i'ead~-fm'doc~sr.f.f12!2JIG/ )

number, the NRC may not conduct or sponsor, and a person is not required to respond to, the infomnation collection.

1. FACILITY NAME

~

• DOCKET NUMBER

~*PAGE Edwin I. Hatch Unit 1 05000321 1 OF3

4. TITLE Condition Prohibited by Tech Specs Due to Secondary Containment lnoperability

5. EVENT DATE

6. LEA NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.

MONTH DAY YEAR Edwin I. Hatch Unit 2 05000366 FACILITY NAME DOCKET NUMBER 01 20 2018 2018

- 001

- 00 03 21 2018

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: 'Check all that apply) 0 20.2201 (b) 0 20.2203(a)(3)(i) 0 50.73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A) 1 0 20.2201 (d) 0 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(B) 0 50.73(a)(2)(viii)(B) 0 20.2203(a)(1) 0 20.2203(a)(4) 0 50.73(a)(2)(iii) 0 50.73(a)(2)(ix)(A) 0 20.2203(a)(2)(i) 0 50.36(c)(1 )(i)(A) 0 50.73(a)(2)(iv)(A) 0 50.73(a)(2)(x)

10. POWER LEVEL 0 20.2203(a)(2)(ii) 0 50.36(c)(1 )(ii)(A) 0 50.73(a)(2)(v)(A) 0 73.71(a)(4) 0 20.2203(a)(2)(iii) 0 50.36(c)(2) 0 50.73(a)(2)(v)(B) 0 73.71(a)(5) 0 20.2203(a)(2)(iv) 0 50.46(a)(3)(ii) 181S0.73(a)(2)(v)(C) 0 73.77(a)(1) 095 0 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(D) 0 73.77(a)(2)(i) 0 20.2203(a)(2)(vi) 18JS0.73(a)(2)(i)(B) 0 50.73(a)(2)(vii) 0 73.n(a)(2)(ii) 0 50.73(a)(2)(i)(C) 00THER Specify in Abstract below or in NRC Form 366A

12. LICENSEE CONTACT FOR THIS LEA ICENSEE CONTACT

~~LEPHONE NUMBER (Include Area Code)

Edwin I. Hatch I Jimmy Collins - Licensing Supervisor 912-537-2342

13. COMPLETE ONE UNE FOR EACH COM,PONENT FAILURE DESCRIBED IN THIS REPORT

CAUSE

SYSTEM COMPONENT MANU-REPORTABLE

CAUSE

SYSTEM COMPONENT MANU-REPORTABLE FACTURER TOEPIX FACTURER TOEPIX y

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR 0 YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 181 NO SUBMISSION DATE it'BSTRACT (Umit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)

On January 20, 2018 at 1950 EST with Unit 1 at approximately 95 percent rated thermal power and Unit 2 at approximately 100 percent rated thermal power, a Secondary Containment drawdown test was completed unsatisfactorily due to not being able to establish greater than or equal to 0.20 inches of vacuum water gauge within 10 minutes in accordance with Technical Specification (TS) Surveillance Requirement (SA) 3.6.4.1.3. This test was performed using the 1 A, 1 B, and 2A Standby Gas Treatment (SBGT) trains.

Operations personnel entered the reql:fired action statement for an inoperable secondary cont~inment. A subsequent secondary containment drawdown test was successfully performed at 2236 EST using the 1 B, 2A, and 28 SBGT trains. The required action statement was therefore exited due to meeting the surveillance requirement.

Subsequent troubleshooting revealed degraded secondary containment door seals. The degraded secondary containment doors were repaired and a satisfactory secondary containment drawdown test using the 1 A, 1 B, and 2A SBGT trains was completed on January 25, 2018. As part of the corrective actions, the secondary containment door preventative maintenance procedure will be revised with enhanced actions to prevent recurrence of degraded components.

Event Description

On January 20, 2018 at 1950 EST with Unit 1 at approximately 95 percent rated thermal power and Unit 2 at approximately 100 percent rated thermal power, the Type A" Secondary Containment drawdown test was completed unsatisfactorily due to not being able to establish greater than or equal to 0.20 inches of vacuum water gauge within 10 minutes in accordance with Technical Specification (TS} Surveillance Requirement (SR) 3.6.4.1.3. This test was performed using the 1 A, 1 B, and 2A Standby Gas Treatment (SBGT} (EllS Code: BH) trains. Operations personnel therefore entered the required action statement for an inoperable secondary containment. A subsequent secondary containment drawdown test was successfully performed at 2236 EST using the 1 B, 2A, and 2B SBGT trains. The required action statement was therefore exited due to meeting the surveillance requirement.

Due to the successful completion of the secondary containment drawdown test without using the 1 A SBGT train, it was reasoned that the 1 A SBGT train was unable to develop sufficient flow such that a differential pressure of greater than or equal to 0.20 inches water gauge could be established. However, based on subsequent troubleshooting testing, it was revealed that the 1 A train could maintain its design flowrate and the initial failure of the secondary containment drawdown test was due to degraded secondary containment components. Troubleshooting activities identified that degraded secondary containment door seals were the cause of the unsatisfactory test. These degraded conditions were repaired and a satisfactory secondary containment drawdown test using the 1 A, 1 B, and 2A SBGT trains was completed on January 25, 2018.

This event is reportable per 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications since secondary containment was inoperable longer than its allowed TS LCO time. This event is also reportable per 10 CFR 50.73(a)(2)(v)(C) as a condition that could have prevented the fulfillment of the safety function of a system needed to control the release of radioactive material since secondary containment does not have redundancy. However, since a successful secondary containment test was performed within the required LCO completion time after the initial unsatisfactory test without performing any repairs, this event is not reportable as a safety system functional failure per NEI 99-02.

Event Cause Analysis

This cause of the event is due to in-leakage through degraded secondary containment door seals. Increased work traffic for pre-outage activities led to degraded seal integrity for secondary containment doors. It was also discovered that a cable penetration was inadequately repaired with duct tape. After continued troubleshooting to gain margin, two secondary containment isolation dampers were found to not be able to fully close due to broken bolts and mechanical stop interference issues.

Safety Assessment

The secondary containment system contains the primary containment system and other nuclear systems, and limits the ground-level release of airborne radioactive material. It provides a means for a controlled elevated release of the building atmosphere such that offsite doses from a fuel-handling or loss-of-coolant accident (LOCA) will be below the guideline values stated in 10 CFR 50.67. It is designed to provide secondary containment when the grimary_ containment is closed and in service, and to provide primary containment when Page 2 of 3 (06-2016)

U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET (See NUREG-1 022, R.3 for instruction and guidance for completing this form http://www.nrc.oovlrecd!JSH1!!Vl!bc-colleclibns/1111!lreqs'staNsc10221r3/)

Eslimaled burden per response Ia comply wilh !his mandalory colleclion request 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.

Reported lessons learned are incorporaled inlo !he licensing process and led back Ia induslry.

Send commenls regarding burden estimale Ia !he FOIA, Privacy and Information CoUeclions Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555*0001, or by e-mail Ia lnfocollecls.Resource@nrc.gov, and Ia !he Desk Officer, Office of lnformalion and Regulalory Affairs, NEOB-10202, {3150.0104), Office of Management and Budget, Washinglon, DC 20503.11 a means used 10 impose an informalion colleclion does no! display a currenlly valid OMB conlrol number, !he NRC may no! conducl or sponsor, and a person is not required to respond Ia, the information colfeclion.

3. LEA NUMBER Edwin I. Hatch Unit 1 05000-321 YEAR I SEQUENTIAL I REV NUMBER NO.

2018

- 001

- 00 the primary containment is open, e.g., during a refueling outage. Secondary containment is isolated on the same signals that actuate the Standby Gas Treatment (SBGT) system. Activation of the SBGT demonstrates the integrity of the reactor building (secondary containment). The SBGT system establishes and maintains a negative pressure (0.2 inches water) within the secondary containment.

The following four types of accidents are analyzed for potential dose consequences: a LOCA, a main steam line break (MSLB), a control rod drop accident (CRDA), and a fuel handling accident (FHA). Of these four accidents, only the LOCA analysis relies upon operability of secondary containment and the SBGT system to mitigate doses. This analysis assumes secondary containment draws down to a differential pressure (dp) of 0.2 inches water gauge with respect to the atmosphere in 10 minutes. Therefore, since a successful secondary containment drawdown test was performed using the 1 B, 2A, and 28 SBGT trains after the initial unsatisfactory test, this event is considered to have very low safety significance.

Corrective Actions

The degraded door seals were repaired. An open penetration and two degraded secondary containment isolation dampers were also repaired to improve margin. As part of an extent of condition review, additional isolation dampers were identified as degraded and will be repaired. The secondary containment door preventative maintenance procedure will be revised such that future secondary containment door inspections are subject to a smoke leak test. The corrective maintenance procedure for the associated isolation damper actuators will also be revised to require a visual inspection to confirm the secondary containment isolation dampers stroke fully close.

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