05000425/LER-1917-001, Regarding Power Supply Failure Results in Operation in a Condition Prohibited by Technical Specifications

Regarding Power Supply Failure Results in Operation in a Condition Prohibited by Technical Specifications

ML17117A347
Person / Time
Site:	Vogtle
Issue date:	04/27/2017
From:	Taber B Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-17-0455 LER 17-001-00
Download: ML17117A347 (5)

LER-1917-001, Regarding Power Supply Failure Results in Operation in a Condition Prohibited by Technical Specifications

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(viii)(B) 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)(vii), Common Cause Inoperability
4251917001R00 - NRC Website

text

~ Southern Nuclear April27, 2017 Docket No:

50-425 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 B. Keith Tabar Vice President VogUe Units 1-2 Vogtle Electric Generating Plant-Unit 2 Licensee Event Report 2017-001-00 7821 River RD Waynesboro GA. 30830 706-848-0002 tel 706-848-3321 fax NL-17-0455 Power Supply Failure Results in Operation in a Condition Prohibited by Technical Specifications Ladies and Gentlemen:

In accordance with the requirements of 10 CFR 50.73(a)(2)(i)(B), Southern Nuclear Operating Company is submitting the enclosed Licensee Event Report, 2017-001-00 for Vogtle Electric Generating Plant Unit 2. This letter contains no NRC commitments. If you have any questions, please contact Dom Sutton at (706) 848-1428.

Respectfully submitted, f,. tvtJ'"'--_

B. Keith Taber Vice President - Plant Vogtle Units 1 &2 - SNC BKT/KCW Enclosure: Unit 2 Licensee Event Report 2017-001-00 cc:

Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Best, Executive Vice President & Chief Nuclear Officer Mr. R. D. Gayheart, Fleet Operations General Manager Mr. M.D. Meier, Vice President-Regulatory Affairs Mr. B. J. Adams, Vice President - Engineering Mr. D. D. Sutton, Regulatory Affairs Manager-Vogtle 1 & 2 RType: CVC7000 U.S. Nuclear Regulatory Commission Ms. C. Haney, Regional Administrator Mr. M. D. Orenak, NRR Project Manager-Vogtle 1 & 2 Mr. M. F. Endress, Senior Resident Inspector-Vogtle 1 & 2

Vogtle Electric Generating Plant - Unit 2 Licensee Event Report 2017-001-00 Power Supply Failure Results in Operation in a Condition Prohibited by Technical Specifications Enclosure Unit 2 Licensee Event Report 2017-001-00

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 104-2017) the NRC may not conduct or sponsor. and e person is not required to respond to. the information collection.

LICENSEE EVENT REPORT (LER)

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

(See NUREG-1 022, R.3 for instruction and guidance for completing this form http://www.nrc govlreadlnq-rmldoc-collections/nureas/staff/sr1 022/r31) 05000425 i.PAGE Vogtle Electric Generating Plant 1 OF3

4. TITLE Eower 5.u.ool.v£.ailu.re.Results..in Oo.eration ~.a Condilion.Erabi.pite.d. bv Technical c.

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EVENT DATE I

6. LER NUMBER _

7. REPORT DATE j==

8. OTH_ER FACILITIES INVOLVED MONTH DAY YEAR YEAR NUMBER NO.

MONTH DAY YEAR i 05000 l

I SEQUENTIAL REV ?j' I FACILITY NAME

'oOCKET NUMBER

-~ _ 9_..,, 2017... 2017

• 001

_ OO -

4 2 1 2017 FACILITY NAME 10-0-CK_E_T_N_U_M_B_ER--I I

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11. lliiS REPORT IS SUBMITTED PURSUANT TO TiiE REQUIREMENTS OF 10 CFR §: Check all that apply) 1 0 20.2201(b) 0 20.2203(a)(3)(i) 0 50.73(a)(2)(1i)(A) 0 50.73(a)(2)(vlii)(A) 0 20.2201(d) 0 20.2203(a)(3)(11) 0 50.73(a)(2)(1i)(B) 0 50.73(a)(2)(viii)(B) 0 20.2203(a)(1) 0 20.2203(a)(4) 0 50.73(a)(2)(111) 0 50.73(a)(2)(ix)(A) 0 20.2203(a)(2)(1) 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)(1il) 0 50.36(c)(2) 0 50.73(a)(2)(v)(B) 0 73.71(a)(5) 100 0 20.2203(a)(2)(iv) 0 50.46(a)(3)(11) 0 50.73(a)(2)(v)(C) 0 73.77(a)(1) 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) l8150.73(a)(2)(i)(B) 0 50.73(a)(2)(vii)

(3 73.77(a)(2)(ii) o so.73(a)(2JmccJ 00THER Specify in Abslrllct below or in NRC Form 366A

12. LICENSEE CONTACT FOR THIS LER UCENSEE CONTACT

~ELEPHONE NUMBER {Include Area Code)

Dom.§.~tton, RegulatQ_ry Affairs Manager, Vogtle Electric Generating Plant

__1_706-848-1428 ___ _

13. COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT ____________ 1

CAUSE

I SYSTEM l COMPONENT i MANU-J REPORTABLE CAUSE I SYSTEM

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j 14.SUPPLEME~ALREPOR~EXPECTED.

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15. EX-PE_C_T_E_D __ MONTH

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YEAR [g) YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 0 NO i SUBMISSION 1

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!ABSTRACT (Umit to 1400 spaces, I.e., approximately 15 single-spaced fypewritten line~

DATE

______ L_ _____ l __

On January 19, 2017, a power supply that supports operation of one of two ventilation supply fans for the 2-A Emergency Diesel Generator (EDG) failed. The Vogtle Electric Generating Plant (VEGP) Technical Specifications (TS),

3.8.3 Condition F requires that if a ventilation supply fan is inoperable, it must be restored within 14 days or the associated EDG must be declared inoperable. This condition was not identified by operators at the time of occurrence due to no failure indication is available. Therefore, the power supply was not repaired within the required completion time and the EDG should have declared inoperable and TS 3.8.1. Condition B entered. On February 16, 2017, because the completion time forTS 3.8.1 Condition B expired, the unit should have placed in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Mode 4 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. These actions were not taken and Unit 2 operated in a condition prohibited by TS.

On February 22, 2017, the second power supply failed on this EDG resulting in the second ventilation supply fan being inoperable. Because both power supplies and therefore both ventilation supply fans were inoperable, the required TS 3.8.3 action is to immediately declare the EDG inoperable. However, this condition was not identified by the operators since no failure indication is available. On March 8, 2017, the completion time expired and the unit operated in a condition prohibited by TS. During a monthly surveillance run on March 8, the EDG tachometer was discovered not working, the EDG was shutdown, declared inoperable, and troubleshooting revealed the power supplies were failed.

Both power supplies were replaced on March 9, 2017 and the EDG was restored to operable status.

A

Event Description

On March 15, 2017 during a review of past events with the Unit 2 A-Train, Emergency Diesel Generator (EDG)[DG], it was discovered that a power supply that supports the "B" ventilation supply fan [VJ] failed on January 19, 2017. The EDG has two power supplies supporting a common speed sensing circuit and one ventilation fan each. The EDG can successfully operate with one power supply supporting the speed sensing circuit. The "A" ventilation fan immediately starts upon EDG start. The "B" ventilation fan enters stand-by on EDG start and operates once thermostat temperature reaches 93F. Per Vogtle TS 3.8.3 Condition F, if a ventilation supply fan is not operable, the fan must be restored operable within 14 days or the associated EDG must be declared inoperable. This restoration time was not met as the condition was not identified by operators because no indication is available to reveal the failure while the EDG is in standby. Per TS 3.8.3, Condition G, operators should have declared the associated EDG inoperable on February 2, 2017 and entered TS 3.8. 1. Condition B. TS 3.8. 1 allows for an extended completion time if certain conditions are met in Condition B.6. A review of the actions required to support this extended completion time of 14 days was completed and all conditions could be met during this time, therefore, use of this extended completion time is appropriate.

On February 16, 2017, the TS 3.8.1 completion time for Condition B.6 expired. Operators should have taken action, as required in Condition H, to place the unit In Mode 3 in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Mode 4 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Because the power supply was not identified as failed, these actions were not taken and the plant operated in a condition prohibited by TS from February 16, 2017 until the power supply was replaced on March 9, 2017.

Subsequently, on February 22, 2017, the second power supply failed resulting in both ventilation supply fans being inoperable. This condition was also not identified by the operators due to no indication being available to reveal the failure. The TS required action for this condition (TS 3.8.3 Condition G) is to immediately declare the associated EDG inoperable. Declaration by the operators of the 2A EDG being inoperable would have allowed the additional 14-day completion time as discussed earlier, and the actions that were required to be taken, could have been taken during this time and would have allowed for this 14-day completion time.

On March 8, the 2A EDG was started for a monthly surveillance; however, the local tachometer indication was not working and the operators shut down the EDG and declared it inoperable. During troubleshooting, the two power supplies were found failed and both were replaced March 9, 2017. Once the work was complete, the 2A EDG ran successfully. The power supplies on the B-Train EDG and the Unit 1 EDGs were checked and none of them were failed.

The unit operated in Mode 1 at 100 percent power during the entire time of these events.

Because the unit operated in a condition prohibited by Technical Specifications, these events are reportable as required by 10 CFR 50.73(a)(2)(i)(B).

B. Cause of Event

The cause of the operation in a condition prohibited by TS was a failure to recognize that the power supply had failed and rendered the ventilation supply fans inoperable.

C. Safety Assessment

During the first condition prohibited by Tech Specs, the EDG was able to start and load its associated safety related electrical bus because the second power supply was still available. As discussed in the Tech Spec Bases, except in extreme temperatures, only one fan is needed to keep the temperature in the EDG room below the limit of 120F. During the time that this fan was inoperable, the outside temperatures remained well below the 93F limit for single fan operation as listed in the TS Bases. Because the EDG could perform its required safety function during this time, the safety significance of this event was very low.

For the second condition prohibited by Tech Specs, the EDG would have started but would not have automatically loaded the electrical bus due to an electrical permissive from the speed sensing circuit powered by the failed NRC FORM 3668 (04-2017)

Page 2 of 3 (04-2017)

U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150*0104 EXPIRES: 3/31/2020

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LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET (See NUREG-1 022, R.3 for instruction and guidance for completing this form h!tp:/lwww.nrc.gov/readinq-rm/doc-<:ollections/nuregs/staff/sr1 022/r3/)

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

1-- ----------------.. --- --'-'--'---~----

______ _ [_

3. LERNllliiBER Vogtle Electric Generating Plant 05000-425 NUMBER No.

YEAR 1 SEQUENTIAL I REV i 2017

-~001 _ _[ - 00 power supplies. During this time, the opposite train EDG was fully operable and both power supplies were verified to be operationaL This would have allowed an electrical safety bus to be powered during an accident. Additionally, all required offsite electrical sources were available and the combustion turbines with blackstart capabilities, adequate fuel, along with the associated underground power line at Plant Wilson were available and were within their required reliability parameters. Because of these additional measures for supplying the safety related electrical bus, the safety significance of this event was low.

D. Corrective Actions

Both power supplies for the 2A EDG were replaced when it was recognized that they were failed and additional investigation is ongoing as to the cause of the power supply failure and additional corrective actions will be taken once the cause is found. Monitoring equipment has been installed on the 2A EDG to monitor this power supply while the investigation is ongoing.

E. Previous Similar Events

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