05000366/LER-2017-003, Regarding Primary Containment Isolation Penetration Exceeded Overall Allowable Technical Specification Leakage Limits

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Regarding Primary Containment Isolation Penetration Exceeded Overall Allowable Technical Specification Leakage Limits
ML17104A292
Person / Time
Site: Hatch Southern Nuclear icon.png
Issue date: 04/13/2017
From: Vineyard D
Southern Nuclear Operating Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-17-0640 LER 17-003-00
Download: ML17104A292 (6)
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LER-2017-003, Regarding Primary Containment Isolation Penetration Exceeded Overall Allowable Technical Specification Leakage Limits
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded
10 CFR 50.73(a)(2)(v), Loss of Safety Function
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)(i)(B), Prohibited by Technical Specifications
10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
10 CFR 50.73(a)(2)(i)
3662017003R00 - NRC Website
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text

David A. Vineyard Hatch Nuclear Plant A Southern Nuclear V1ce President-Plant Hatch 11028 Hatch Parkway North Baxley, GA 31513 April13, 2017 Docket Nos.: 50-366 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Unit 2 Licensee Event Report 2017-003-00 912 537 5859 tel 912 366 2077 fax NL-17-0640 Primary Containment Isolation Penetration Exceeded Overall Allowable Technical Specification Leakage Limits Ladies and Gentlemen:

In accordance with the requirements of 10 CFR 50.73(a)(2)(ii)(A) and 10 CFR 50.73(a)(2)(v)(C), Southern Nuclear Operating Company (SNC) hereby submits the enclosed Licensee Event Report.

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

Respectfully submitted, David A. Vineyard Vice President - Hatch DAV/jcb Enclosure: LEA 2017-003-00

U.S. Nuclear Regulatory Commission NL-17-0640 Page2 cc:

Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bast, Executive Vice President & Chief Nuclear Officer Mr. D. R. Vineyard, Vice President-Hatch Mr. M. D. Meier, Vice President-Regulatory Affairs Mr. R. D. Gayheart, Fleet Operations General Manager Mr. B. J. Adams, Vice President-Engineering Mr. G. L. Johnson, Regulatory Affairs Manager-Hatch RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Ms. C. Haney, Regional Administrator Mr. R. Hall, NRR Project Manager-Hatch Mr. D. H. Hardage, Senior Resident Inspector-Hatch

Edwin I. Hatch Nuclear Plant Unit 2 Licensee Event Report 2017-003-00 Primary Containment Isolation Penetration Exceeded Overall Allowable Technical Specification Leakage Limits

NRCFORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 1013112018 (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 />

.......... ;\\

LICENSEE EVENT REPORT (LER)

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

~~~

Send comments regarding burden estimate to the FOIA, Privacy and tnfomnation Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail

~.....1' (See Page 2 for required number of digits/characters for each block) to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory (See NUREG-1 022, R3 for instruction and guidance for completing this form Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503.1f a means used to impose an information collection does not display a currently valid OMB control httg:/lwww.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1 022/r3D number, the NRC may not conduct or sponsor, and a person is not required to respond to, the infomnation collection.

3. PAGE Edwin I. Hatch Nuclear Plant Unit 2 05000366 1 OF3
4. TITLE Primary Containment Isolation Penetration Exceeded Overall Allowable Technical Specification Leakage Limits
5. EVENT DATE
6. LER 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 FACILITY NAME DOCKET NUMBER 02 19 2017 2017

- 003
- 00 4

13 2017

9. OPERA liNG MODE
11. THIS REPORT IS SUBMITIED PURSUANT TO THE REQUIREMENlS OF 10 CFR §: (Check all that apply)

D 20.2201(b)

D 20.2203(a)(3)(i) 181 50.73(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(A) 5 D 20.2201 (d)

D 20.2203(a)(3)(ii)

D 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(viii)(B)

D 20.2203(a)(1)

D 20.2203(a)(4)

D 50.73(a)(2)(iii)

D 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 73.71(a)(4)

D 20.2203(a)(2)(iii)

D 50.36(c)(2)

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

D 73.71(a)(5) 0 D 20.2203(a)(2)(iv)

D 50.46(a)(3)(ii) 181 50. 73(a)(2)(v)(C)

D 73.77(a)(1)

D 20.2203(a)(2)(v)

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

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

D 73.77(a)(2)(i)

D 20.2203(a)(2)(vi)

D 50.73(a)(2)(i)(B)

D 50.73(a)(2)(vii)

D 73.77(a)(2)(ii)

D 50.73(a)(2)(i)(C) 0 OTHER Specify in Abstract below or in NRC Form 366A

12. LICENSEE CONTACT FOR THIS LER ICENSEE CONTACT

~LEPHONE NUMBER (Include Atea Code)

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

13. COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT

CAUSE

SYSTEM COMPONENT MANU-REPORTABLE

CAUSE

SYSTEM COMPONENT MANU-REPORTABLE FACTURER TOEPIX FACTURER TOEPIX X

88 ISV F130 y

14. SUPPLEMENTAL REPORT EXPECTED
15. EXPECTED MONTH DAY YEAR 0 YES (If yes, complete 15. EXPECTED SUBMISSION DATE)

[gi NO SUBMISSION DATE ABSTRACT (Umit fo 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)

On February 19, 2017 at 2323 EST, with Unit 2 at 0 percent rated thermal power due to a refueling outage, the Unit 2 outboard drywell ventilation penetration isolation valve 2T48F320 (EllS Code: ISV) failed local leak rate testing (LLRT).

Previously on February 7, 2017 at 1427 EST, the inboard drywell ventilation penetration isolation valve 2T48F319 had also failed LLRT. Therefore, due to both primary containment isolation valves (PCIVs) in this penetration flow path exceeding the maximum allowable leakage rate (La), this event represents a failure of the associated penetration (2T23X26) to maintain primary containment integrity per Technical Specifications (TS).

Actions were taken to repair both of the PCIVs and on February 21, 2017, the valves were successfully retested. During the next scheduled Unit 2 refueling outage, the 2T 48F320 isolation valve will be completely rebuilt. Also a corrective maintenance rebuild procedure will be developed for Fisher Series 9200 butterfly valves.

NRC FORM 366 (06-2016)

Event Description

On February 19, 2017 at 2323 EST, with Unit 2 at 0 percent rated thermal power due to a refueling outage, the Unit 2 outboard drywell ventilation penetration isolation valve 2T 48F320 (EllS Code: ISV) failed local leak rate testing (LLRT). Previously on February 7, 2017 at 1427 EST, the inboard drywell ventilation penetration isolation valve 2T48F319 had also failed LLRT. Therefore, due to both primary containment isolation valves (PCIVs) in this penetration flow path exceeding the maximum allowable leakage rate (La), this event represents a failure of the associated penetration (2T23X26) to maintain primary containment integrity per Technical Specifications (TS).

The as-found results of the LLRT rendered penetration 2T23X26 inoperable. Actions were made to repair both of the PCIVs and on February 21, 2017, the valves were successfully retested. Observed leakage rates were determined to be acceptable.

Failed Components Information

Master Parts List Number: 2T48F319 and 2T48F320 Manufacturer: Fisher Controls Co.

Model Number: Model9220 Type: Isolation Valves

Event Cause Analysis

- 00 The cause of the both the 2T 48F319 and 2T 48F320 PCIVs exceeding their acceptable maximum allowable leakage limits was attributed to inadequate conditions related to the disc sealing ring that was found on both valves. Specifically for the 2T48F320 isolation valve, it was revealed that the set screws that are used to hold in place the retaining plate for the disc sealing ring were all loose. This allowed the ring to loosen over time, creating a gap between the valve disc and the ring.

Safety Assessment

This event is reportable per 10 CFR 50. 73(a)(2)(ii)(A) due to an event or condition that resulted in the condition of the nuclear power plan~ including its principle safety barriers, being seriously degraded. This event is also reportable per 10 CFR 50. 73(a)(2)(v)(C) as an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material due to the failure of the penetration flow path to meet its maximum allowable leakage rate.

The function of the PCIVs, in combination with other accident mitigation systems, is to limit fission product release during and following postulated Design Basis Accidents (DBAs) to within limits. Primary containment isolation ensures that the release of radioactive material to the environment will be consistent with the assumptions used in the analyses for a DBA Operability requirements for the PCIVs help ensure that an adequate primary containment boundary is maintained during and after an accident by minimizing potential paths to the environment. This provides assurance that the primary containment function as assumed in safety analyses is maintained. Two barriers in series are provided for each penetration such that no single credible failure or malfunction of an active component can result in a loss of isolation or leakage that

._____~ceeds limits assumed in the safety analyses.

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 htto:l/www. nrc.gov/reading-rm/doc-collections/nu reqs/staff/sr1 0221r3D 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 />.

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

Send 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 lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means 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 Edwin I. Hatch Nuclear Plant Unit 2 05000-366 YEAR I

SEQUENTIAL I

NUMBER 2017

- 003 A calculation was performed to determine the impact of drywell ventilation penetration 2T23X26 leakage exceeding La on post-LOCA doses, where La is the maximum allowable primary containment leakage rate per TS 5.5.12. The calculation evaluated doses to the main control room (MCR), the technical support center (TSC), the exclusion area boundary (EAB), and the low population zone (LPZ). The results of the calculation show that with an assumed containment leakage rate of 3 times La, and an assumed MSIV leakage of twice the as-found leakage rate, doses to the MCR, TSC, EAB and LPZ were all within the regulatory limits. The actual as-found overall leakage rate of primary containment was determined to be 2.3 times La, 23 percent less than the assumed value.

Therefore, based on the aforementioned calculation results, the potential safety consequences of exceeding the maximum allowable TS primary containment leakage rate by a factor of 2.3 are very low due to radiation doses in the MCR, TSC, EAB and LPZ all being within regulatory limits. Radiation doses would not have exceeded federal limits during a design basis event.

Corrective Actions

The ring assemblies on both the 2T48F319 and 2T48F320 valves were replaced and the set screws were adjusted. The valves were successfully retested with an observed acceptable leakage rate. During the next scheduled Unit 2 refueling outage, the 2T 48F320 isolation valve will be completely rebuilt Also a corrective maintenance rebuild procedure will be developed specifically for Fisher Series 9200 butterfly valves.

Previous Similar Events

LER 2011-001-01 On April16, 2011, during the Hatch Nuclear Plant 2R21 refueling outage, a local leak rate test (LLRT) was performed on torus purge supply primary containment isolation valve (PCIV) 2T48-F324 which is associated with primary containment penetration 2T23-X205. At that time, plant engineers and technicians were performing an LLRT for penetration 2T23-X205 when it was discovered that both PCIVs (2T 48-F309 and 2T48-F324) had failed their LLRTs for this penetration. This resulted in the penetration leakage exceeding the overall allowable leakage (La) requirements by the Technical Specifications (TS) for primary containment.

Although the event documented above is similar, the corrective actions taken did not prevent the 2T48F319 or 2T48F320 valves from failing their LLRT.

REV NO.

- 00 Page 3 of 3

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