05000281/LER-2019-001, Re Foreign Material in Breaker Contact Causes Pressurizer Power Operated Relief Valve Block Valve Inoperability

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Re Foreign Material in Breaker Contact Causes Pressurizer Power Operated Relief Valve Block Valve Inoperability
ML19098A163
Person / Time
Site: Surry Dominion icon.png
Issue date: 04/01/2019
From: Mladen F
Virginia Electric & Power Co (VEPCO)
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
19-104 LER 2019-001-00
Download: ML19098A163 (4)
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LER-2019-001, Re Foreign Material in Breaker Contact Causes Pressurizer Power Operated Relief Valve Block Valve Inoperability
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)
10 CFR 50.73(a)(2)(viii)(A)
10 CFR 50.73(a)(2)(viii)
10 CFR 50.73(a)(2)(ix)
10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(x)
10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2812019001R00 - NRC Website
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text

APR O 1 2019 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555-0001

Dear Sir or Madam:

10CFR50.73 Virginia Electric and Power Company Surry Power Station 5570 Hog Island Road Surry, Virginia 23883 Serial No.:

19-104 SPS:

TSC Docket No.: 50-281 License No.: DPR-37 Pursuant to 10CFR50.73, Virginia Electric and Power Company hereby submits the following Licensee Event Report applicable to Surry Power Station Unit 2.

Report No. 50-281 / 2019-001-00 This report has been reviewed by the Station Facility Safety Review Committee and will be forwarded to the Management Safety Review Committee for its review.

Enclosure Commitment contained in this letter: None Very truly yours, F. Mladen Site Vice President Surry Power Station cc:

U.S. Nuclear Regulatory Commission, Region II Marquis One Tower, Suite 1200 245 Peachtree Center Ave., NE Atlanta, GA 30303-1257 NRC Senior Resident Inspector Surry Power Station

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2017) httP.;/Jwww.,nrc.9_o_v/rea9j119-rrn/d9~-c.ol[§~tions/nur~taff/sr1022/r3Q the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

3. PAGE Surry Power Station, Unit 2 05000 281 I OF 3
4. TITLE Foreign Material in Breaker Contact Causes Pressurizer Power Operated Relief Valve Block Valve lnoperability
5. EVENT DATE
6. LER 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 05000 FACILITY NAME DOCKET NUMBER 01 29 2019 2019..

001. 00 04 01 2019 05000

9. OPERATING MODE
11. THIS REPORT IS SUBMrTTED 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)

N 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 so: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 13.71(a}(4)

D 20.2203(a)(2)(iii)

D so.3a(c)(2)

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

D 73.71(a)(5)

D 20.2203(a)(2)(iv)

D so.4a(a}(3)(ii)

D 50.73(a)(2)(v}(C)

D 13.77(a)(1) 100 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)

[Z] 50.73(a}(2)(i)(B)

D 50.73(a)(2)(vii)

D 73.77(a)(2)(ii)

!f* \\\\ l * ~'.
:f.;
  • .**. *r D 50.73(a}(2)(i)(C)

D OTHER Specify in Abstract below or in NRC Fonm 366A

12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT TELEPHONE NUMBER (Include Area Code)

Barry Garber (757) 365-2725 MANU-REPORTABLE MANU-REPORTABLE

CAUSE

SYSTEM COMPONENT FACTURER TOEPIX 1-,i

CAUSE

SYSTEM COMPONENT FACTURER TOEPIX A

AB CNTR C770 y

1,.~

14. SUPPLEMENTAL REPORT EXPECTED
15. EXPECTED MONTH DAY YEAR DYES (Jfyes, complete 15. EXPECTED SUBMISSION DATE)

[Z] NO SUBMISSION DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)

On December 27, 2018, at 08:28 hours, with Units 1 and 2 at 100% power, the breaker for a Unit 2 Pressurizer Power Operated Relief Valve (PORV) block valve tripped on thermal over-current while performing a periodic test. Troubleshooting commenced, but the condition could not be duplicated, and the block valve (a motor operated valve) (MOV) was tested and successfully cycled several times with no issues. The valve was declared operable and returned to service at 14: 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br />.

On January 29, 2019, additional testing and inspection of the block valve Motor Control Center (MCC) breaker was performed, and a nylon brush bristle was found within the contactor, inhibiting one phase of power to the MOV motor.

Operability of the valve was required on December 4, 2018, when Unit 2 was in Intermediate Shutdown and heating up for return to power operation. Due to foreign material located in the contactor causing inconsistent operation, the block valve was conservatively determined to be inoperable since maintenance was performed on the MCC breaker during the Unit 2 2018 refueling outage. On January 29, 2019, the bristle was found and removed from the contactor, and the PORV block valve was returned to operable status.

This report is submitted pursuant to 10 CFR 50.73(a)(2)(i)(B) due to operation prohibited by Technical Specifications.

NRC FORM 366 (04-2017)

of 3

1.0 DESCRIPTION OF THE EVENT YEAR 2019

  • SEQUENTIAL NUMBER 001 REV NO.

00 On December 27, 2018, during periodic testing, Operations attempted to close one Reactor Coolant System (RCS)

Pressurizer PORV block valve (a motor operated valve) (MOV) [EIIS-AB-V]. After the block valve switch was manipulated in the closed direction, the control board light indication was not as expected; both the open and closed indications were extinguished. The valve was declared inoperable at 08:28 hours, resulting in an unplanned entry into a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Technical Specifications (TS) Limiting Condition for Operation (LCO). Troubleshooting identified that the Thermal Overload device (TOL) had tripped, and therefore, the valve had not closed as intended. The TOL was reset, and the trip condition could not be repeated. The block valve was cycled successfully several times, and MOV stroke time, amperage, and light indications were all satisfactory. The PORV block valve was declared operable at 14:18 hours, stopping the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> LCO.

PORV block valve and motor control center breaker [EIIS-EC-BKR] testing conducted on January 29, 2019, revealed that, although the block valve stroked normally on that day, the valve close-control contactor [EIIS-AB-CNTR] was only passing current'on two of the three phases. Subsequent inspection of the contactor internals identified a nylon brush bristle lodged within the "C" phase contact, which inhibited one phase of current to the MOV motor [El IS-EC-MO]. The bristle was removed from the motor control contactor assembly, and the PORV block valve was returned to operable status. It was determined that the bristle was left in the contactor during maintenance performed during the 2018 Unit 2 refueling outage. It was conservatively determined that the valve had been inoperable for 56 days, from the time it was required to be operable (when the Reactor Coolant System average temperature exceeded 350 degrees F after refueling) on December 4, 2018, at 04:35 hours, until January 29, 2019, at 18: 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />, when the bristle was removed from the motor control contactor, and the PORV block valve was returned to service.

The pressurizer* PORV [EIIS-AB-RV] provides RCS isolation in series with the PORV block valve. On two occasions during the time the affected PORV block valve was inoperable, the in series PORV was disabled in the closed position for testing; this occurred on December 4, 2018, from 12:47 to 13:01 hours, and also on January 3, 2019, from 08:00 to 08: 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />.

This report is submitted pursuant to 10 CFR 50.73(a)(2)(i)(B) due to operation prohibited by Technical Specifications.

2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS

The normally open PORV block valve provides isolation in the unlikely event of a leaking or partially open PORV. No leakage occurred during the period of PORV block valve inoperability. Other than the brief period the in series PORV was inoperable, mitigating safety system equipment was operable during the time that the PORV block valve was inoperable. Additionally, the block valve functioned as required in all instances other than the one time on December 27, 2018. Therefore, the risk significance and impact were very low, and there were no safety consequences as a result of this event.

3.0 CAUSE

OF THE EVENT YEAR 2019 SEQUENTIAL NUMBER 001 REV NO.

00 The cause of the PORV block valve motor thermal overcurrent trip was foreign material (a nylon brush bristle) lodged within the valve close-control contactor, which inhibited one phase of current to the MOV motor. Higher than normal amps experienced by the other two phases caused the TOL to trip, thereby de-energizing the motor control circuit.

Although the foreign material exclusion close-out after maintenance was adequate for the MCC breaker assembly, a contributing cause to the event was an informal close-out review of the MCC breaker contactor subassembly. Also contributing to the event was the practice of using nylon bristle brushes for cleaning MCC breaker sub-components during the performance of breaker maintenance.

4.0 IMMEDIATE CORRECTIVE ACTIONS

The use of nylon bristle brushes for cleaning MCC breaker subcomponents was discontinued. A human performance review was conducted, and expectations were reinforced concerning foreign material exciusion during subcomponent close-out.

5.0 ADDITIONAL CORRECTIVE ACTIONS

A formal process for MCC breaker subcomponent foreign material exclusion will be implemented.

6.0 ACTIONS TO PREVENT RECURRENCE Long term actions recommended by the Level of Effort Evaluation will be implemented by the corrective action program.

7.0 SIMILAR EVENTS

None 8.0 MANUFACTURER/MODEL NUMBER Cutler-Hammer/ NEMA Size 1 Motor Starter Contactor Series A1 (Citation) No. A50CNVO

9.0 ADDITIONAL INFORMATION

Unit 1 remained at full power and was not affected by the Unit 2 PORV block valve inoperability for the duration of time the Unit 2 RCS PORV block valve was inoperable. At no time while the Unit 2 PORV block valve was inoperable was either Unit 2 PORV called upon to actuate. Other than the in series pressurizer PORV inoperability as discussed in sections 1.0 and 2.0, there were no other inoperable structures, systems, or components that contributed to the incident. Page 3

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