ML18152A864

LER 2018-004-00 for Pilgrim Nuclear Power Station, Automatic Emergency Diesel Generator System Actuation Caused by Loss of Offsite Power

ML18152A864
Person / Time
Site:
Issue date:	05/14/2018
From:	Miner P J Entergy Nuclear Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
2.18.031 LER 2018-004-00
Download: ML18152A864 (6)

Text

• ~Entergx May 14, 2018 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Entergy Nuclear Operations, Inc. Pilgrim Nuclear Power Station 600 Rocky Hill Road Plymouth, MA 02360

SUBJECT:

Licensee Event Report 2018-004-00, Automatic Emergency Diesel Generator System Actuation Caused By Loss of Offsite Power Pilgrim Nuclear Power Station Docket No. 50-293 Renewed License No. DPR-35 LETTER NUMBER: 2.18.031

Dear Sir or Madam:

The enclosed Licensee Event Report 2018-004-00, Automatic Emergency Diesel Generator System Actuation Caused By Loss of Offsite Power, is submitted in accordance with Title 1 O Code of Federal Regulations 50.73. If you have any questions or require additional information, please contact me at (508) 830-7127.

There are no regulatory commitments contained in this letter. Sincerely, IJ:~ Peter J. er Manage Regulatory Assurance PJM/sc

Attachment:

Licensee Event Report 2018-004-00, Automatic Emergency Diesel Generator System Actuation Caused By Loss of Offsite Power Entergy Nuclear Operations, Inc. Pilgrim Nuclear Power Station cc: Mr. David C. Lew Acting Regional Administrator, Region I U.S. Nuclear Regulatory Commission 2100 Renaissance Blvd., Suite 100 King of Prussia, PA 19406-2713 Mr. John Lamb, Senior Project Manager Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0-8C2A Washington, DC 20555-0001 USNRC Senior Resident Inspector Pilgrim Nuclear Power Station Letter No. 2.18.031 Page 2 of 2 Attachment Letter Number 2.18.031 Licensee Event Report 2018-004-00, Automatic Emergency Diesel Generator System Actuation Caused By Loss of Offsite Power (3 Pages)

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2017)

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 />. :~~. LICENSEE EVENT REPORT (LER) Reported lessons learned are incorporated into the licensing process and fed back to industry.

r ' Send comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. \ rf'J (See Page 2 for required number of digits/characters for each block) Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to lnfocollects.

~4' ...... / Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, (See NUREG-1022, R.3 for instruction and guidance for completing this form 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 0MB control number, httg://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3D the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.

1. FACILITY NAME 12. DOCKET NUMBER .PAGE Pilarim Nuclear Power Station 05000-293 1 OF3 14. TITLE 2018-004-00, Automatic Emen:iencv Diesel Generator System Actuation Caused Bv Loss of Offsite Power 5. EVENT DATE 6. LER NUMBER 7. REPORT DATE 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO. MONTH DAY YEAR NIA 1\1/A 03 13 2018 2018 -004 00 05 14 2018 FACILITY NAME DOCKET NUMBER N/A N/A 9. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: Check all that aoolv) N D 20.2201 (bl D 20.2203(a)(3)(il D 50.73(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(A)

D 20.2201 (d) D 20.2203(a)(3)(iil D 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(viii)(B)

D 20.2203(a)(1 l D 20.2203(a)(4)

D so.73(a)(2)(iiil D 50.73(a)(2)(ix)(A)

D 20.2203(a)(2)(i)

D 50.36(c)(1)(i)(A) l:8l 50.73(a)(2)(iv)(A)

D 50.73(a)(2)(x)

10. POWER LEVEL D 20.2203(a)(2)(iil 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)(s) 000 D 20.2203(a)(2)(iv)

D so.46(a)(3)(ii)

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

D 73.77(a)(1)

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)(il 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 50.73(a)(2)(i)(C) 0 OTHER Specify in Abstract below or in NRC Form 366A 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT rELEPHONE NUMBER (Include Area Code) Mr. Peter J. Miner-Regulatory Assurance Manager 508-830-7127 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 TOEPIX C FK y 14. SUPPLEMENTAL REPORT EXPECTED 15. EXPECTED MONTH DAY YEAR D YES (If yes, complete 15. EXPECTED SUBMISSION DATE) C8] NO SUBMISSION DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) On March 13, 2018 at approximately 10:02 am [EDT], with the reactor in Cold Shutdown, Pilgrim Nuclear Power Station experienced a loss of offsite power. The loss of both incoming 345KV lines to the Startup rTransformer and the loss of the 23KV line to the Shutdown Transformer were due to weather related conditions associated with Winter Storm Skylar. The loss of offsite power lasted long enough for the associated Startup Transformer relay to transmit a valid auto start signal to both Emergency Diesel Generators and trip the non-safety related buses A 1 through A4. There was minimal impact from this occurrence as the Emergency Diesel Generators had been started manually several hours prior to the auto start signal being received.

The Emergency Diesel Generators were already providing power to the A5 and A6 Emergency Buses. rThis event is reportable per the requirements of Title 1 O Code of Federal Regulations 50.73(a)(2)(iv)(A) due to ~he receipt of a valid automatic start signal by the Emergency Diesel Generators.

rThere was no impact to public health and safety. NRC FORM 366 (04-2017)

NRC FORM 366A (04-2017)

U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 3/31/2020 ,.,Ill~ /~:... * ' 'l / ..... LICENSEE EVENT REPORT (LER) CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3D 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 Information Services Branch (T-2 F43), U,S, Nuclear Regulatory Commission, Washington, DC 20555-0001, or by 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 0MB 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. LER NUMBER YEAR Pilgrim Nuclear Power Station 05000-293 2018 BACKGROUND:

SEQUENTIAL NUMBER -004 REV NO, -00 rrhe station preferred Alternating Current (AC) power source (Startup Transformer) provides AC power to all station auxiliaries required for startup and shutdown and is normally in use when the unit AC power source is unavailable.

The preferred AC power source is that power supply which furnishes electric energy under accident or post-accident conditions.

At Pilgrim Nuclear Power Station (PNPS), this is an offsite power source (either of two 345KV lines) which supply power to the Startup Transformer.

The station's auxiliary power system distributes AC power necessary for startup, operation, or shutdown of station loads. All portions of this system receive AC power from the unit AC power source or the preferred AC power source. The emergency service portions of this distribution system can also receive AC power from the secondary AC power source, the standby AC power source, or the station blackout AC power source. The standby AC power source provides two independent diesel generators as the onsite source of AC power to ~he emergency service portions of the station Auxiliary Power Distribution System. Each onsite source provides AC power to safely shut down the reactor, maintain safe shutdown conditions, and operate all auxiliaries necessary for station safety. EVENT DESCRIPTION:

On March 13, 2018 at approximately 10:02 am [EDT], with the reactor in Cold Shutdown, Pilgrim Nuclear Power Station experienced a loss of offsite power. The loss of both incoming 345KV lines to the Startup Transformer and the loss of the 23KV line to the Shutdown Transformer were due to weather related conditions associated with Winter Storm Skylar. The loss of offsite power (LOOP) lasted long enough for the associated Startup Transformer (SUT) relay to transmit a valid auto start signal to both Emergency Diesel Generators (EDGs) and trip the non-safety related buses A 1 through A4. There was minimal impact rom this occurrence as the EDGs had been started manually several hours prior to the auto start signal being received.

The EDGs were already providing power to the A5 and A6 Emergency Buses. CAUSE OF THE EVENT: rrhe direct cause of the event was a loss of offsite power caused by Winter Storm Skyler. CORRECTIVE ACTIONS: The Corrective Actions taken as part of the Root Cause Evaluation for Winter Storm Juno have been evaluated and are acceptable at mitigating risk during severe winter storms. No changes to storm preparation or criteria in the procedure are required at this time. The actions taken prior to Winter Storm Skylar were proactive in ensuring power was available to Emergency Buses A5 and A6. rrhe Station will continue to interface with the transmission operator to improve reliability of 345 kV lines prior to storms that can cause a LOOP. The intent of this action is to confirm appropriate steps are being ~aken prior to a storm to limit faults offsite on the 345 kV lines. NRG FORM 366A (04-2017)

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,--------NRC FORM 366A (04-2017)

U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 3/31/2020 LICENSEE EVENT REPORT (LER) CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r30 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 Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by 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 0MB 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. LEA NUMBER YEAR Pilgrim Nuclear Power Station 05000-293 2018 SAFETY CONSEQUENCES:

SEQUENTIAL NUMBER -004 REV NO. -00 rThe actual consequence was reliance on onsite emergency AC power to supply safety buses A5 and A6 and the loss of normal service to buses A 1, A2, A3, and A4. There were no other actual consequences.

The risk associated with the actual event was considered low because at the time of occurrence the unit was offline and safety systems were powered from their associated EDG via emergency buses A5 and A6. Since shutdown conditions in the severe weather procedure were met during the storm and a LOOP occurred, the procedural guidance was effective in ensuring power was available to appropriate Station loads. The risk associated with loss of buses A 1 through A4 was low. This is non-safety related equipment, but is needed for normal heat sink availability.

The risk associated with reliance on onsite emergency AC power to supply safety buses A5 and A6 was low. This risk was low since the plant was in Cold Shutdown condition with decay heat removal having been previously established using equipment powered from the EDG supplied safety buses. In addition the Station Blackout-Diesel Generator remained available to provide partial power to Emergency Buses A5 or A6 loading if the respective EDG was lost. Therefore, based on the above information there was no adverse impact on the public health or safety. REPORT ABILITY: rThis event is reportable per the requirements of Title 1 O Code of Federal Regulations 50.73(a)(2)(iv)(A) due to the receipt of a valid automatic start signal by the EDGs. PREVIOUS EVENTS: LER 2015-001-00, Loss of 345KV Power Resulting in Automatic Reactor Scram During Winter Storm Juno LER 2013-009-00, Loss of Offsite Power and Reactor Scram LER 2013-003-00, Loss of Offsite Power Events Due to Winter Storm Nemo

REFERENCES:

CR-PNP-2015-00558 CR-PNP-2018-02144 NRC FORM 366A (04-2017)

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