05000529/LER-2016-001, Regarding Main Steam Isolation Valve Actuator Train Inoperable Due to Low Nitrogen Pre-Charge Pressure

Regarding Main Steam Isolation Valve Actuator Train Inoperable Due to Low Nitrogen Pre-Charge Pressure

ML16285A412
Person / Time
Site:	Palo Verde
Issue date:	10/10/2016
From:	Lacal M APS, Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
102-07347-MLL/RAC LER 16-001-00
Download: ML16285A412 (7)

LER-2016-001, Regarding Main Steam Isolation Valve Actuator Train Inoperable Due to Low Nitrogen Pre-Charge Pressure

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)(v), Loss of Safety Function 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)
5292016001R00 - NRC Website

text

10 CFR 50.73 A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek MARIA L. LACAL Senior Vice President Nuclear Regulatory and Oversight Palo Verde Nuclear Generating Station P.O. Box 52034 Phoenix, AZ 85072 Mail Station 7605 Tel 623 393 6491 102-07347-MLL/RAC October 10, 2016 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Palo Verde Nuclear Generating Station (PVNGS) Unit 2 Docket No. STN 50-529 / License No. NPF 51 Licensee Event Report 2016-001-00 Enclosed please find Licensee Event Report (LER) 50-529/2016-001-00 that has been prepared and submitted pursuant to 10 CFR 50.73. This LER reports a condition prohibited by Technical Specification Limiting Condition for Operation 3.7.2, Main Steam Isolation Valves (MSIVs). PVNGS identified a low nitrogen pre-charge pressure on the MSIV train A accumulator on August 9, 2016 due to nitrogen leakage.

Engineering evaluation determined that the MSIV train A accumulator had been inoperable greater than the 7-day Required Action Completion Time.

In accordance with 10 CFR 50.4, copies of this LER are being forwarded to the Nuclear Regulatory Commission (NRC) Regional Office, NRC Region IV, and the Senior Resident Inspector.

Arizona Public Service Company makes no commitments in this letter. If you have questions regarding this submittal, please contact Mark McGhee, Nuclear Regulatory Affairs Department Leader, at (623) 393-4972.

Sincerely, MLL/RAC/akf Enclosure cc:

K. M. Kennedy NRC Region IV Regional Administrator S. P. Lingam NRC NRR Project Manager for PVNGS C. A. Peabody NRC Senior Resident Inspector PVNGS Lacal, Maria L(Z06149)

Digitally signed by Lacal, Maria L(Z06149)

DN: cn=Lacal, Maria L(Z06149)

Date: 2016.10.10 12:26:07

- 07'00'

NRC FORM 366 (11-2015)

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (11-2015)

LICENSEE EVENT REPORT (LER)

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

APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 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 internet e-mail to Infocollects.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.

1. FACILITY NAME Palo Verde Nuclear Generating Station (PVNGS), Unit 2

2. DOCKET NUMBER 05000529

3. PAGE 1 OF 6

4. TITLE Main Steam Isolation Valve Actuator Train Inoperable due to Low Nitrogen Pre-Charge Pressure

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REV NO.

MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 08 09 2016 2016 -

001

- 00 10 10 2016 FACILITY NAME DOCKET NUMBER

9. OPERATING MODE

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

10. POWER LEVEL 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 73.71(a)(4) 100 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C) 73.77(a)(1) 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(D) 73.77(a)(2)(i) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(vii) 73.77(a)(2)(ii) 50.73(a)(2)(i)(C)

OTHER Specify in Abstract below or in LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET

8. PREVIOUS SIMILAR EVENTS

PVNGS has not reported a similar event in the past 3 years. LER 50-529/2012-003-00 identified a similar condition where a gradual loss of nitrogen pre-charge pressure resulted in a violation of TS LCO 3.7.2. The evaluation of the 2012 condition determined the hydraulic fluid level alarm setpoint, which is intended to be an indicator of nitrogen loss, may not be capable of ensuring that the nitrogen pre-charge in the accumulators is sufficient to perform the MSIV actuator fast close function under all conditions.

The corrective actions implemented weekly hydraulic fluid level trending to ensure timely discovery of a loss of nitrogen condition affecting operability of an MSIV accumulator. The corrective actions did not prevent the event in this LER because they did not include actions to ensure an understanding of the limitations of reservoir monitoring and the need for timely verification of nitrogen pre-charge pressure.

Specifically, hydraulic fluid level is an indication of nitrogen leakage but not an indication of adequate nitrogen pre-charge.