05000423/LER-2016-001, Regarding Automatic Reactor Trip on Reactor Coolant System Low Flow Due to Loss of B Reactor Coolant Pump

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Regarding Automatic Reactor Trip on Reactor Coolant System Low Flow Due to Loss of B Reactor Coolant Pump
ML16082A268
Person / Time
Site: Millstone Dominion icon.png
Issue date: 03/16/2016
From: Daugherty J
Dominion Nuclear Connecticut
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
16-066 LER 16-001-00
Download: ML16082A268 (6)


LER-2016-001, Regarding Automatic Reactor Trip on Reactor Coolant System Low Flow Due to Loss of B Reactor Coolant Pump
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(iv)(A), System Actuation

10 CFR 50.73(a)(2)(iv)(B), System Actuation

10 CFR 50.73(a)(2)(i)

10 CFR 50.73(a)(2)(vii), Common Cause Inoperability

10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded

10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition

10 CFR 50.73(a)(2)(iii)

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)(i)(B), Prohibited by Technical Specifications
4232016001R00 - NRC Website

text

Dominion Nuclear Connecticut, Inc.

Rope Ferry Rd., Waterford, CT 06385 Mailing Address: P.O. Box 128 Waterford, CT 06385 dam.com U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 LICENSEE EVENT REPORT 2016-001a00 MAR 1 6 2016 Serial No.

MPS Lic./AV Docket No.

License No.16-066 RO 50-423 NPF-49 AUTOMATIC REACTOR TRIP ON REACTOR COOLANT SYSTEM LOW FLOW DUE TO LOSS OF 'B' REACTOR COOLANT PUMP This letter forwards Licensee Event Report (LER) 2016-001-00 documenting an event that occurred at Millstone Power Station Unit 3, on January 25, 2016. This LER is being submitted pursuant to 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in manual or automatic actuation of systems listed in 10 CFR 50.73(a)(2)(iv)(B), initially reported via event notification 51682 pursuant to 10 CFR 50.72 (b)(2)(iv)(B) and 1o CFR 50.72 (b)(3)(iv)(A).

If you have any questions or require additional information, please contact Mr. Thomas G.

Cleary at (860) 444-4377.

Sincerely,

/)~

Joh/ R. Daugherty Site Vice President - Millstone Attachments: 1 Commitments made in this letter: None

cc:

U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd.

Suite 100 King of Prussia, PA 19406-2713 R.V. Guzman NRC Project Manager Millstone Unit 2 and 3 U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 C-2 Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station Serial No.16-066 Docket No. 50-423 Licensee Event Report 2016-001-00 Page 2 of 2

ATTACHMENT Serial No.16-066 Docket No. 50-423 Licensee Event Report 2016-001-00 LICENSEE EVENT REPORT 201 G-001 Eoo AUTOMATIC REACTOR TRIP ON REACTOR COOLANT SYSTEM LOW FLOW DUE TO LOSS OF 'B' REACTOR COOLANT PUMP MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC.

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (11-2015)

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

3. PAGE Millstone Power Station Unit 3 05000423 1 OF 3
4. TITLE Automatic Reactor Trip on Reactor Coolant System Low Flow Due to Loss of 'B' Reactor Coolant Pump
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 05000 FACILITY NAME DOCKET NUMBER 01 25 2016 2016 -

001

- 00 03 16 2016 05000
9. OPERATING MODE
11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)

D 20.2201cbl D 20.2203CalC3lCil D 50.73(a)(2)(i)(C)

D 50.73(a)(2)(vii)

D 20.2201 cctl D 20.2203(a)(3)(ii)

D 50.73(a)(2)(ii)(A)

D 50. 73(a)(2)(viii)(A) 1

  • D 20.2203(a)c1 l D 20.2203(a)C4l D 50.73(a)(2)(ii)(B)

D 50. 73(a)(2)(viii)(B)

D 20.2203(a)(2)Cil D 50.36(c)(1 )(i)(A)

D 50.73(a)(2)(iii)

D 50. 73(a)(2)(ix)(A)

10. POWER LEVEL D 20.2203(a)(2)(ii)

D 50.36(c)(1)(ii)(A)

~ 50. 73(a)(2)(iv)(A)

D 50.73(a)(2)(x)

D 20.2203(a)(2)cml D 5o.36(c)(2)

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

D 13.11calC4l 100 D 20.2203(a)(2)(iv)

D 5o.46(a)(3)(ii)

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

D 13. 11 calC5l D 20.2203(a)(2)(v)

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

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

D OTHER D 20.2203(a)(2)(vi)

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

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

Specify in Abstract below or in

1. EVENT DESCRIPTION

On January 25, 2016 at 014 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> an automatic reactor trip occurred at Millstone Power Station Unit 3 (MPS3) while the unit was in Mode 1, operating at 100 percent power. The Reactor Protection System (RPS) was initiated due to a reactor coolant system loop low flow. All control rods fulli inserted into the reactor. The auxiliary feedwater pumps started as designed on low steam generator level and operators maintained steam generator level. All other post trip actions were standard and all safety systems operated as expected, stabilizing the plant.

The 'B' Reactor Coolant Pump (RCP) trip was (;aused by failure of one of three motor capacitors on the RCP motor. The failed capacitor on the affected RCP motor was replaced and the integrity of the motor windings, cabling, breaker, and associated protective relays were verified.

Based on an assessment of the event, the risk impact was determined to be v.ery small. There were no radiological challenges and the health and safety of the public were not affected.

The actuation of the reactor protection system and the automatic start of the auxiliary feedwater pumps is being reported in accordance with 10 CFR 50. 73(a)(2){iv)(A) as an event that resulted in manual or automatic actuation of systems listed in 10 CFR 50. 73(a)(2)(iv)(B).

2. CAUSE

The direct cause of the 'B' RCP trip, which resulted in an automatic reactor trip due to partial loss of forced reactor coolant flow, was due to the failure of one of the three RCP motor capacitors. Failure of the capacitor provided a short to ground.

3. ASSESSMENT OF SAFETY CONSEQUENCES

Final Safety Analysis Review (FSAR) Section 15.3.1 presents an analysis of a Partial Loss of Forced Reactor Coolant Flow (one RCP). The analysis presented spans 10 seconds from the onset of the flow coast down to beyond the time of minimum Departure from Nucleate Boiling Ratio (3.6 seconds).

The event as presented in the* FSAR contains conservative assumptions typical of safety analysis.

These include rapid coast down characteristics, maximum trip delay times, most ad.verse time in cycle reactivity feedbacks, etc.

Plant computer data and log entries were examined to verify that the actual plant response was bounded with respect to that in the safety analysis. Examination of the plant response showed that the January 25th partial loss of forced reactor coolant flow due to the loss of 'B' RCP transient was well bounded by the FSAR analysis.

The event was considered uncomplicated as defined by the Reactor Oversight Process. In addition, all equipment designed to remove decay heat was available prior to the event and functioned properly during the event. The event was not a significant operational event. Therefore, the event posed no actual or potential hazard to public health and safety.

4. CORRECTIVE ACTION

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

6. LER NUMBER YEAR I

SEQUENTIAL I NUMBER 2016 001 REV NO.

00 3

3. PAGE OF 3

The failed motor capacitor was replaced on the 'B' RCP.

Additional corrective actions are being taken in accordance with the Millstone Corrective Action Program.

5. PREVIOUS OCCURRENCES

Millstone Power Station Unit 3 has no previous occurrences.

6. Energy Industry Identification System (EllS) codes:
  • Pump-P
  • Steam Generator-SG
  • Capacitor-CAP
7. MANUFACTURER/PART NUMBER Capacitor: Westinghouse/6060B7H01 N

1. EVENT DESCRIPTION

On January 25, 2016 at 014 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> an automatic reactor trip occurred at Millstone Power Station Unit 3 (MPS3) while the unit was in Mode 1, operating at 100 percent power. The Reactor Protection System (RPS) was initiated due to a reactor coolant system loop low flow. All control rods fulli inserted into the reactor. The auxiliary feedwater pumps started as designed on low steam generator level and operators maintained steam generator level. All other post trip actions were standard and all safety systems operated as expected, stabilizing the plant.

The 'B' Reactor Coolant Pump (RCP) trip was (;aused by failure of one of three motor capacitors on the RCP motor. The failed capacitor on the affected RCP motor was replaced and the integrity of the motor windings, cabling, breaker, and associated protective relays were verified.

Based on an assessment of the event, the risk impact was determined to be v.ery small. There were no radiological challenges and the health and safety of the public were not affected.

The actuation of the reactor protection system and the automatic start of the auxiliary feedwater pumps is being reported in accordance with 10 CFR 50. 73(a)(2){iv)(A) as an event that resulted in manual or automatic actuation of systems listed in 10 CFR 50. 73(a)(2)(iv)(B).

2. CAUSE

The direct cause of the 'B' RCP trip, which resulted in an automatic reactor trip due to partial loss of forced reactor coolant flow, was due to the failure of one of the three RCP motor capacitors. Failure of the capacitor provided a short to ground.

3. ASSESSMENT OF SAFETY CONSEQUENCES

Final Safety Analysis Review (FSAR) Section 15.3.1 presents an analysis of a Partial Loss of Forced Reactor Coolant Flow (one RCP). The analysis presented spans 10 seconds from the onset of the flow coast down to beyond the time of minimum Departure from Nucleate Boiling Ratio (3.6 seconds).

The event as presented in the* FSAR contains conservative assumptions typical of safety analysis.

These include rapid coast down characteristics, maximum trip delay times, most ad.verse time in cycle reactivity feedbacks, etc.

Plant computer data and log entries were examined to verify that the actual plant response was bounded with respect to that in the safety analysis. Examination of the plant response showed that the January 25th partial loss of forced reactor coolant flow due to the loss of 'B' RCP transient was well bounded by the FSAR analysis.

The event was considered uncomplicated as defined by the Reactor Oversight Process. In addition, all equipment designed to remove decay heat was available prior to the event and functioned properly during the event. The event was not a significant operational event. Therefore, the event posed no actual or potential hazard to public health and safety.

4. CORRECTIVE ACTION

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

6. LER NUMBER YEAR I

SEQUENTIAL I NUMBER 2016 001 REV NO.

00 3

3. PAGE OF 3

The failed motor capacitor was replaced on the 'B' RCP.

Additional corrective actions are being taken in accordance with the Millstone Corrective Action Program.

5. PREVIOUS OCCURRENCES

Millstone Power Station Unit 3 has no previous occurrences.

6. Energy Industry Identification System (EllS) codes:
  • Pump-P
  • Steam Generator-SG
  • Capacitor-CAP
7. MANUFACTURER/PART NUMBER Capacitor: Westinghouse/6060B7H01 N