05000416/LER-2018-004, Potential Loss of Safety Function Due to Concurrent Inoperability of Two Diesel Generators

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Potential Loss of Safety Function Due to Concurrent Inoperability of Two Diesel Generators
ML18107A152
Person / Time
Site: Grand Gulf Entergy icon.png
Issue date: 04/17/2018
From: Emily Larson
Entergy Operations
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
GNRO-2018/00018 LER 2018-004-00
Download: ML18107A152 (7)
v • d • e


LER-2018-004, Potential Loss of Safety Function Due to Concurrent Inoperability of Two Diesel Generators
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(v), Loss of Safety Function
4162018004R00 - NRC Website
v • d • e

text

GNR0-2018/00018 April 17, 2018 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Entergy Operations, Inc.

P. 0. Box756 Port Gibson, MS 39150 Eric A. Larson Site Vice President Grand Gulf Nuclear Station Tel. (601) 437-7500 10CFR50.73

SUBJECT:

Licensee Event Report 2018-004-00, Potential Loss of Safety Function Due to Concurrent lnoperability of.Two Diesel Generators Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29

Dear Sir or Madam:

Attached is Licensee Event Report 2018-004-00, Potential Loss of Safety Function Due to Concurrent lnoperability of Two Diesel Generators. This report is being submitted in accordance with 1 OCFR50. 73(a)(2)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function.

This letter contains no new commitments. If you have any questions or require additional information, please contact Douglas Neve at 601-437-2103.

Sincerely,

~ _/

z_a ;/e, Eric A. Larson Site Vice President Grand Gulf Nuclear Station EAL/tdf

Attachment:

Licensee Event Report 2018-004-00 cc: see next page

GNR0-2018/00018 Page 2 of 2 U.S. Nuclear Regulatory Commission ATTN: Mr. Siva Lingam Mail Stop OWFN 8 81 Rockville, MD 20852-2738 NRC Senior Resident Inspector Grand Gult1 Nuclear Station Port Gibson, MS 39150 U. S. Nuclear Regulatory Commission ATTN: Mr. Kriss Kennedy, NRR/DORL (w/2)

Mail Stop OWFN 8 81 Washington, DC 20555-0001

Attachment

\\

Licensee Event Report (LER) 2018-0040-00

NRCFORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO: 3150-0104 EXPIRES: 03/31/2020 (02-2018)

,C.,J>il ffl'!Ct,(-t_,,

, the NRC may not conduct or sponsor, and a oerson is not reauired to resoond to the information collection.

  • -1. r'acmty*Name
2. DocketNumber 3.:Page Grand Gulf Nuclear Station 05000416 1 OF4
4. Title Potential Loss of Safetv Function Due to Concurrent lnooerabilitv of Two Diesel Generators
5. Event Date
6. LER Number
7. Report Date
8. Other Facilities Involved Sequential Rev Facility Name Docket Number Month Day Year Year Month Day Year NIA Number No.

05000 NIA 02 18 2018 2018

- 004
- 00 04 17 2018

.Facility.Name Docket.Number NIA 05000 NIA

9. Operating Mode N/A N/A N/A Abstract (Limit to 1400 spaces, i.e., approximately 14 single-spaced typewritten lines)

On February 14, 2018, the Grand Gulf Nuclear Station Division 2 diesel generator (DG) was removed from service for maintenance. On February 18, 2018, at 0006 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, while in Mode 1 at 97 percent power, the Division 3 DG

- experienced a lockout and was declared inoperable. Technical Specification 3;8.1 Condition E was entered for two DGs inoperable at that time. On February 18, 2018, at 0355 hours0.00411 days <br />0.0986 hours <br />5.869709e-4 weeks <br />1.350775e-4 months <br />, Division 2 DG maintenance was completed, the
  • diesel-was* returned -to-service, and *Condition -E was exited. Division 3 DG was -restored -to -operable status-on February 18, 2018, at 1257 hours0.0145 days <br />0.349 hours <br />0.00208 weeks <br />4.782885e-4 months <br />.

The Division 3 DG lockout was caused by inadequate operation procedures, which failed to detect an elevated jacket water temperature condition. The elevated jacket water temperature was caused by a malfunctioning jacket water temperature control switch. Corrective actions include replacement of the temperature control s.~itch, and revision of the operation* procedures.

- Division-1-DG, which -power-s -one low :pressure core -injection -pump and -one -low pressure *core -spray -pump, -remained operable. An evaluation of Chapter 15 accident analyses demonstrated that, with just Division I, peak cladding temperatures and cladding oxidation remained within the Cycle 21 licensing basis of <1730 degrees F and <3%,

respectively.

NRC FORM 366 (02-2018)

A. PLANT CONDITIONS PRIOR TO THE EVENT YEAR 2018

3. LER NUMBER SEQUENTIAL NUMBER
- 004 Prior to the event Grand Gulf Nuclear Station (GGNS) Unit 1 was operating in Mode 1 at approximately 97 percent power in steady state conditions. The division 2 diesel generator (DG) [EIIS: DG] was inoperable due to preplanned maintenance and c*ontributed to the event. The division 2 electrical service was being supplied with offsite power and remained available and functional. There were no other structures, systems, or components that were known to be inoperable that contributed to the event.

B. DESCRIPTION

On February 17, 2018, at 2353 hours0.0272 days <br />0.654 hours <br />0.00389 weeks <br />8.953165e-4 months <br />, the high pressure core spray (HPCS) diesel [EIIS: BG][DG] trouble alarm was received in the control room. At 0006 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, while operators were in route to the diesel, control room operators received diesel engine trip and not ready for start alarms. Investigation revealed that the r*

Division 3 HPCS DG was tripped and not available for autostart. Division 3 DG was declared inoperable and Technical Specification 3.8.1 Condition E, for two required DGs inoperable, was entered on February 18, 2018, at 0006 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Division 3 electrical service was being supplied with offsite power and remained available and functional.

Operations personnel detected a local jacket water temperature alarm due to high jacket water temperature.

Operators assumed manual control of the Division 3 diesel jacket water temperature, restored the temperature to an acceptable level, cleared the Division 3 DG trips, and restored the DG to available status on February 18, 2018, at 0037 hours4.282407e-4 days <br />0.0103 hours <br />6.117725e-5 weeks <br />1.40785e-5 months <br />.

The Division 2 DG was returned to service and made operable on February 18, 2018 at 0355 hours0.00411 days <br />0.0986 hours <br />5.869709e-4 weeks <br />1.350775e-4 months <br />.

Technical Specification 3.8.1 Condition E was exited at that time.

REV NO.

- 00 The Division 3 diesel generator high jacket water temperature was caused by a malfunctioning temperature control switch [EIIS: TSl Investigation indicated the temperature switch had failed approximately 7 days prior to the event, and it took that long for the system temperature to reach trip setpoint. Operations procedures were inadequate to detect the temperature increase prior to reaching the trip setpoint. The switch was replaced and retested satisfactorily, and the Division 3 diesel generator was returned to operable status on February 18, 2018 at 1240 hours0.0144 days <br />0.344 hours <br />0.00205 weeks <br />4.7182e-4 months <br />.
  • C. REPORT ABILITY This report is made pursuant to 1 OCFR50.73(a)(2)(v)(D) for any event or condition that could have prevented fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident.

This event was reported under 10CFR50.72(b)(3)(v)(D) in ENS notification 53227.

NRG FORM 3668 (02-2018)

U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020 (04-2017)

LICENSEE EVENT REPORT (LER)

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

1. FACILITYNAME
2. DOCKET NUMBER YEAR Grand Gulf Nuclear Station 05000-00416 2018

D. CAUSE

3. LEA NUMBER SEQUENTIAL NUMBER
- 004 REV NO.
- 00 Operator rounds procedure contained non-conservative lube oil temperature limits and did not require monitoring of jacket water temperature.

Neither the HPCS DG system's alarm response instruction nor the HPCS DG system operating instruction contained guidance on manually controlling jacket water heaters to maintain acceptable standby temperatures.

The engineering System Monitoring Plan contained non-conservative lube oil temperature limits and did not require monitoring of jacket water temperature.

Failure'of jacket water temperature switch

E. CORRECTIVE ACTIONS

The following corrective actions are completed or planned.

Completed:

The Division 3 DG jacket water temperature control switch was replaced and retested satisfactorily The lube oil temperature limits in the System Monitoring Plan were revised to be more conservative Planned actions included in the* corrective action program (which may be changed in accordance with the program):

Division 3 DG jacket water temperature monitoring will be added to the operator rounds procedure DG lube oil and jacket water temperature limits in the operator rounds procedure will be revised to a more conservative range Guidance will be added to Division 3 DG operating procedures for manually controlling jacket water heaters to maintain acceptable standby temperatures Division 3 jacket water temperature will be added to the System Monitoring Plan System engineering will review the operator rounds procedures to ensure the proper safety system parameters are monitored and that the established limits are conservative with respect to identifying abnormalities prior to an unplanned loss of the system

F. SAFETY SIGNIFICANCE

Division 2 and 3 DGs were concurrently inoperable for approximately 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. Division I DG, which powers one low pressure core injecti9n (LPCI) pump and one low pressure core spray (LPCS) pump, remained operable during this event. An evaluation of large break and small break loss of coolant events demonstrated that, with just Division I, peak cladding temperature increases from 1632 degrees F to 1719 degrees F but remains below the Cycle 21 licensing basis of <1730 degrees F and well below the 2200 degree F limit in 1 OCFRS0.46. Cladding oxidation remains below the 3% limit. The Division 3 DG was made functional after, the initial 31 minutes and was available to further mitigate an event. Page 3 of 4 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020 (04-2017)

LICENSEE EVENT REPORT (LEA)

CONTINUATION SHEET, (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/readinq-rm/doc-collections/nuregs/staff/sr1022/r3l}

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

Grand Gulf Nuclear Station 05000-0041 6 YEAR 2018

3. LEA NUMBER SEQUENTIAL NUMBER
- 004 The event posed no threat to the health and safety of the general public or to nuclear safety. No technical specification safety limits were violated. Industrial safety was not challenged, and there was no potential:

or actual radiological release during the event.

Therefore, the safety significance of this event is considered to be very low. This condition will not be counted as a safety system functional failure against Performance Indicator M~05, Safety System Functional Failures.

G. PREVIOUS SIMILAR EVENTS

Entergy conducted a three-year review of condition reports related to temperature monitoring of diese~

generators. Two events were found upon review.

A 2015 event was an immersion heater that was stuck in the ON position but did not result in a trip, so it was not considered a failure and no cause evaluation was performed, but the switch was replaced and retested satisfactorily. The action taken in that event would not have prevented this event from occurring.

A 2017 event was the failure of division 3 diesel immersion heaters not being energized. This was caused by foreign material in the associated breaker preventing contacts to make up. The action taken in that event would not have prevented this event from occurring.

1

'-./

REV NO.

- 00 Page 4 of 4

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