ML16271A409

LER 16-002-00 for Millstone Power Station Unit 2 Regarding Manual Reactor Trip Due Loss of Two Circulating Water Pumps

ML16271A409
Person / Time
Site:	Millstone
Issue date:	09/20/2016
From:	Daugherty J R Dominion Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 16-002-00
Download: ML16271A409 (6)

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 2 LICENSEE EVENT REPORT 2016-002-00 MANUAL REACTOR TRIP DUE TO LOSS OF TWO CIRCULATING WATER PUMPS SEP 2 0 2016 Serial No. MPS Lic/TGC Docket No. License No.16-348 RO 50-336 DPR-65 This letter forwards Licensee Event Report (LER) 2016-002-00 documenting an event at Millstone Power Station Unit 2, on August 11, 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). If you have any questions or require additional information, please contact Mr. Jeffry A. Langan at (860) 444-5544. Sincerely, 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 Serial No.16-348 Docket No. 50-336 Licensee Event Report 2016-002-00 Page 2 of 2 NRG Senior Project Manager Millstone Units 2 and 3 U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 c:.2 Rockville, MD 20852-2738 NRG Senior Resident Inspector Millstone Power Station ATTACHMENT Serial No.16-348 Docket No. 50-336 Licensee Event Report 2016-002-00 LICENSEE EVENT REPORT 2016-002-00 MANUAL REACTOR TRIP DUE TO LOSS OF TWO CIRCULATING WATER PUMPS MILLSTONE POWER STATION UNIT 2 DOMINION NUCLEAR CONNECTICUT, INC. l NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (11-2015) Estimated burden per response to comply with this mandalory 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. s Send comments regarding burden estimate to the FOIA, Privacy and lnfonmation Collections . . ; Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by * ., il LICENSEE EVENT REPORT (LER) .. ._. ....... internet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and (See Page 2 for required number of Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, digits/characters for each block) DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection. 1. FACILITY NAME 2. DOCKET NUMBER 3. PAGE Millstone Power Station Unit 2 05000336 1 OF 3 4. TITLE Manual Reactor Trip Due to Loss of Two Circulating Water Pumps 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 MONTH DAY YEAR NUMBER NO. 05000 FACILITY NAME DOCKET NUMBER 08 11 2016 2016 . 002 . 00 09 20 2016 05000 9. OPERATING MODE 11. THIS REPORT IS SUBMITTED 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) 1 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.13(a)(2)(iii) D 50.73(a)(2)(ix)(A) D 20.2203(a)(2)(i) D 50.36(c)(1)(i)(A) [{] 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 so.36(c)(2) D 50.73(a)(2)(v)(B) D 73.71(a)(5) D 20.2203(a)(2)(iv) D so.46(a)(3)(ii) D 50.73(a)(2)(v)(C) D 73.77(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) D 50.73(a)(2)(i)(B) D 50.73(a)(2)(vii) D 73.77(a)(2)(ii) D so.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) Jeffry A Langan, Manager Nuclear Station Licensing (860) 444-5544 13. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT CAUSE SYSTEM COMPONENT MANU-REPORTABLE CAUSE SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPIX FACTURER TO EPIX x EE UJX Eaton N 14. SUPPLEMENTAL REPORT EXPECTED 15. EXPECTED MONTH DAY YEAR DYES (ff yes, complete 15. EXPECTED SUBMISSION DATE) ({]NO SUBMISSION DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) On August 11, 2016 at 09:59 while operating in MODE 1 at 100% power, operators manually tripped the Millstone Power Station Unit 2 reactor due to degraded condenser vacuum caused by the loss of two out of four circulating water pumps (CWPs) ('A' and 'C' CWPs). The reactor trip was uncomplicated and decay heat removal was via the steam dumps to the condenser. All control rods inserted on the reactor trip. All safety systems functioned as required. The 'A' and 'C' CWPs stopped due to a loss of normal control power in the associated variable frequency drive (VFD) system. Both backup uninterruptible power supplies (UPS) in the VFDs associated with the 'A' and 'C' CWPs failed to function resulting in the 'A' and 'C' CWPs stopping. This coincided with a grid disturbance that occurred during a storm. The loss of two out of four CWPs caused a reduction in condenser vacuum. The operators manually tripped the reactor due to degrading condenser vacuum. The associated UPSs were replaced. This event 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). NRC FORM 366 (11-2015)

NRG FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (11-2015) LICENSEE EVENT REPORT (LER) CONTINUATION SHEET 1. FACILITY NAME 2. DOCKET 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 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 NRG may not conduct or sponsor, and a person is not required to respond to, the information collection. 6. LER NUMBER YEAR REV NO. 3. PAGE Millstone Power Station Unit I SEQUENTIAL I NUMBER 05000336 l-------'------'--------1 2 of 3 2016 002 00 1. EVENT DESCRIPTION: On August 11, 2016 at 09:59 while operating in MODE 1 at 100% power, operators manually tripped the Millstone Power Station Unit 2 reactor due to degraded condenser vacuum caused by the loss of two out of four circulating water pumps (CWPs) ('A' and 'C' CWPs). The reactor trip was uncomplicated and decay heat removal was via the steam dumps to the condenser. All control rods inserted on the reactor trip. All safety systems functioned as required. Following the reactor trip, main feedwater continued to be available. The main feedwater regulating valves closed as expected and the main feedwater regulating bypass valves opened as designed. Steam generator level was restored to the desired post trip band using main feedwater. This event 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 'A' and 'C' CWPs stopped due to a loss of normal control power in the associated variable frequency drive (VFD) system. This coincided with a grid disturbance that occurred during a storm. A design feature of the VFD is to swap to a battery back-up redundant uninterruptible power supply (UPS) in the associated VFD system when power is lost or becomes unreliable. Both backup UPSs associated with the 'A' and 'C' CWPs failed to function resulting in the 'A' and 'C' CWPs stopping. The loss of two out of four CWPs caused a reduction in condenser vacuum. The operators manually tripped the reactor due to degrading condenser vacuum. 3. ASSESSMENT OF SAFETY CONSEQUENCES: The operating crew responded to the reactor trip by completing EOP 2525, Standard Post Trip Actions, and entering EOP 2526 Reactor Trip Recovery. All control rods inserted on the reactor trip. With the 'B' and 'D' CWPs still running, condenser vacuum remained adequate for operation of the condenser dump valves following the reactor trip. Steam generator level was restored to the desired post trip band using main feedwater: No safety functions were challenged and plant operation was maintained within the bounds of the FSAR Chapter 14 Safety Analysis. Based on the above discussion, there were no safety consequences for the event. 4. CORRECTIVE ACTION: The associated UPSs were replaced. Additional corrective actions are being taken in accordance with the station's corrective action program. 5. PREVIOUS OCCURRENCES: LER 2013-004-00 Reactor Trip While Backwashing D Waterbox describes a reactor trip due to loss of condenser vacuum. There are no previous occurrences with the same underlying reason or consequences. NRC FORM 366A (11-2015)

NRC FORM 366A (11-2015) i' U.S. NUCLEAR REGULATORY COMMISSION 'i * ..... ** LICENSEE EVENT REPORT (LER) CONTINUATION SHEET 1. FACILITY NAME 2. DOCKET Millstone Power Station Unit 05000336 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 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 NRG may not conduct or sponsor, and a person is not required to respond to, the information collection. YEAR 2016 6. LER NUMBER I SEQUENTIAL I NUMBER 002 REV NO. 00 3. PAGE 3 of 3 6. ENERGY INDUSTRY IDENTIFICATION SYSTEM (EllS) CODES:

• Feedwater System -JB

• Pump-P

• Steam Generator-SG

• Circulating Water System -SG

• Circulating Water Pump -SG, P

• Main Condenser -COND

• Uninterruptible Power Supply -EE NRC FORM 366A (11-2015)