05000373/LER-2022-003-02, Supplement to Main Control Room and Auxiliary Electric Room HVAC Declared Inoperable Due to Multiple Component Failures

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Supplement to Main Control Room and Auxiliary Electric Room HVAC Declared Inoperable Due to Multiple Component Failures
ML22362A013
Person / Time
Site: LaSalle  
Issue date: 12/28/2022
From: Van Fleet J
Constellation Energy Generation, Exelon Generation Co
To:
Office of Nuclear Reactor Regulation, Document Control Desk
References
RA22-065 LER 2022-003-02
Download: ML22362A013 (1)
v • d • e


LER-2022-003, Supplement to Main Control Room and Auxiliary Electric Room HVAC Declared Inoperable Due to Multiple Component Failures
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)
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)(1)
3732022003R02 - NRC Website
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text

Constellation LaSalle County Station 2601 North 21 " Road Marseilles, IL 61341 815-415-2000 Telephone 10 CFR 50.73 RA22-065 December 28, 2022 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

LaSalle County Station, Units 1 and 2 Renewed Facility Operating License No. NPF-11 and NPF-18 NRC Docket Nos. 50-373 and 50-374 Licensee Event Report 2022-003-02, Supplement to Main Control Room and Auxiliary Electric Room HVAC Declared Inoperable Due to Multiple

Component Failures

In accordance with 10 CFR 50.73(a)(2)(v)(D), Exelon Generation Company, LLC (EGC) is submitting Licensee Event Report (LER) Number 2022-003-02 for LaSalle County Station, Units 1 and 2.

There are no regulatory commitments in this letter. Should you have any questions concerning this report, please contact Mr. Dan Mearhoff, Regulatory Assurance Manager, at (815) 415-2800.

Respectfully, John Van Fleet Jr Plant Manager LaSalle County Station

Enclosure:

Licensee Event Report cc:

Regional Administrator-NRC Region Ill NRC Senior Resident Inspector - LaSalle County Station

NRC FORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 08/31/2023 (08-2020)

1. Faclllty Name
2. Docket Number 3.Page LaSalle County Station, Unit 1 05000 -373 1 OF 4
4. Title Main Control Room and Auxiliary Electric Room HVAC Declared Inoperable Due to Multiple Component Failures.
5. Event Date
6. LER Number
7. Report Date
8. Other Facllltles Involved Year Sequential Revision Facility Name Docket Number Month Day Year Number No.

Month Day Year LaSalle County Station, Unit 2 05000-374 05 20 2022 2022 003 02 12 28 2022 Facility Name Docket Number NA NA

9. Operating Mode 1

110. Power Level 100 percent

11. This Report Is Submitted Pursuant to the Requirements of 10 CFR §: {Check all that apply) 10 CFR Part 20 D 20.2203(a)(2)(vl)

D 50.36(c)(2)

D 50.73(a)(2)(1v)(A)

D 50.73(a)(2)(x)

  • 20.2201(b}

D 20.2203(a)(3)(1)

D 50.46(a)(3)(11)

D 50.73(a)(2)(v)(A) 1'0, Cl=II Pllrit 13

  • 20.2201(d}

D 20.2203(a)(3)(11)

  • 50.69(g)

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

D 73.71(a)(4)

D 20.2203(a)(1)

D 20.2203(a)(4)

  • 50.73(a)(2)(1)(A)

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

D 73.71(a)(5)

D 20.2203(a)(2)(1) 10 CIFR Paii21

  • 50.73(a)(2)(1)(B)

[8J 50.73(a)(2)(v)(D)

D 73.77(a)(1)(1)

D 20.2203(a)(2)(11)

D 21.2(c)

  • 50.73(a)(2)(1)(C)

D 50.73(a)(2)(vll)

D 73.77(a)(2)(1)

D 20.2203(a)(2)(111) 10 CFR Pa~ soi

  • 50.73(a)(2)(11)(A)

D 50.73(a)(2)(vlll)(A)

D 73.77(a)(2)(11)

D 20.2203(a)(2)(1v)

  • 50.36(c)(1)(1)(A)
  • 50.73(a)(2)(il)(B}

D 50.73(a)(2)(vlll}(B)

D 20.2203(a)(2)(v)

  • 50.36(c)(1)(11)(A)

D 50.73(a)(2)(111)

D 50.73(a)(2)(1x)(A)

D OTHER (Specify here, in abstract, or NRC 366A).

12. Licensee Contact for this LER Licensee Contact

'Phone Number (Include area code)

CJ Smith, Operations Director (815) 415-2200 Cause System Component Manufacturer Reportable to IRIS.

Cause

System Component Manufacturer Reportable to IRIS D

VI BKR E062 y

14. Supplemental Report Expected I

Month Day Year 12:1 No I D Yes (If yes, complete 15. Expected S 4bmission Date)

15. Expected Submission Date I
6. Abstract (Limit to 1560 spaces, i.e., approximately 15 single-spaced typewritten lines)

On May 20, 2022, both Units 1 and 2 were in Mode 1 and at 100% power. The B train of the Main Control Room Ventilation (VC) and Auxiliary Electric Room Ventilation (VE) was inoperable due to a planned maintenance window. The Main Control Room ventilation envelope consists of both the Main Control Room and the Auxiliary Electric Equipment Room. Both trains of VC and VE were required to be operable at the time of these events.

On 5/20/22 at 0905 and again on 5/23/22 at 1256, various equipment on the A VCNE train tripped following train swaps to support ongoing maintenance activities. This resulted in the A VCNE train being declared inoperable.

With both the A and B trains being simultaneously inoperable, the VCNE system was in a condition that could have prevented fulfillment of a safety function.

The cause of the event is an inadequate breaker setting resulting in the breaker tripping prematurely on fan start.

Plant and System Identification

LaSalle County Station Unit 1 and 2 is a General Electric Boiling Water Reactor with 3546 Megawatts Thermal Rated Core Power. The affected system was the Main Control Room Area Ventilation system (VC) and the Auxiliary Equipment Room Ventilation System (VE).

Condition Prior to Event

Unit(s): 1/2 Reactor Mode(s): 1/1

Description

Date:

Mode(s) Name:

May 20, 2022 Power Operation Time:

0905 CDT Power Level: 100%/100%

On May 20, 2022 the station was executing a 8 VCNE work window and in the following TS actions: 3. 7.4 A.1, restore 8 train to operable status (expires 5/23/22 at 0500) and 3.7.5 A.1, restore B train to operable (expires 6/15/2022 at 0300). The station began procedures to swap to the A train to allow repairs identified during post maintenance testing on the 8 train. After swapping to A VCNE, the A VE return fan tripped and immediately tripped after a second attempt to start.

02 At 0905, the A train was declared inoperable for both TS 3.7.4, (CRAF) and 3.7.5 (MCR ventilation). With both trains ofVCNE inoperable, the Station entered TS 3.7.4 RA E.1 be in mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, TS 3.7.5 RA 8.1 to verify control room area temperature less than 90 degrees once per four hours, and RA 8.2 to restore one control room area ventilation air conditioning subsystem to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

The Electrical Maintenance department performed basic troubleshooting. The fan was restarted and following sufficient run time of the A VE return fan, the A VCNE train was declared operable at 1200. TS actions 3.7.5 E.1 and 3.7.4 B.1 and 8.2 were exited.

On 5/23/2022 the station began activities to swap to A VCNE to allow for system restoration on 8 VCNE. After swapping to A VCNE, the A VE return fan tripped at 1256. Operations reset the breaker and restarted the fan.

The A VCNE train was declared inoperable for CRAF (3.7.4) and MCR ventilation (3.7.5). The station entered the following time clocks: 3.7.4 A.1, restore A train to operable status within 7 days, 3.7.5 RA 8.1 to verify control room area temperature less than 90 degrees once per four hours, and RA 12 to restore one control room area ventilation ~ir conditioning subsystem to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> (Note: The 8 train was declared operable for CRAF on 5/20/22 at 1841 following repairs, but the 8 train re ained in the 3.7.5 MCR ventilation LCO for continued maintenance activities from the previous week that resulted in the condition discussed above on 5/23.)

The B train was fully restored to operable status at 1755 on 5/23/22. TS action 3.7.5 B.1/8.2 were exited. The station declared the A train operable on 5/24/22 at 2230 after completion of an Operability evaluation and subsequent run time.

Cause

The cause of the event is an inadequate breaker setting resulting in the A VE Return Fan breaker tripping prematurely on fan start.

Reportablllty and Safety Analysis SEQUENTIAL NUMBER 003 REV NO.

02 The simultaneous inoperability of the A and B VCNE trains is reportable under 10 CFR 50. 73(a)(2)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function of the structures or systems that are needed to mitigate the consequences of an accident. Two ENS reports were made to the NRC at 1639 CDT on May 20, 2022 (EN 55905) and at 1815 CDT on May 23, 2022 (EN 55908). Both reports were pursuant to 10 CFR

50. 72(b)(3)(v)(D).

The safety significance of this event was minimal. For approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> on 5/20/22, both VCNE trains were inoperable for GRAF and HVAC (TS 3.7.4 and TS 3.7.5). For approximately 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> on 5/23/22, both trains were inoperable for HVAC only (TS 3.7.5). Main Control temperature did not exceed 90 degrees and online risk remained Green throughout the event.

Corrective Actions

Corrective actions taken in response to the conditions were:

Basic troubleshooting was performed.

Operability evaluation was performed prior to declaring VCNE operable after failure of the VC return fan.

Perform inspections and testing of the A and B VCNE trains. Based on testing results perform repairs and breaker adjustments.

Modify model work order for breaker receipt inspection to include trip testing.

Previous Occurrences

LER 373-2014-004 On August 28, 2014, both Units 1 and 2 were in Mode 1 at 100% power. The 'B' train of Auxiliary Electric Equipment Room ventilation (VE) was inoperable due to a planned repair of an oil leak. At 1227 hours0.0142 days <br />0.341 hours <br />0.00203 weeks <br />4.668735e-4 months <br /> CDT, the A VE compressor was not found to be cycling on and off resulting in the 'A' train of VCNE being declared inoperable. With both trains of VCNE inoperable, this resulted in an event or condition that could have prevented the fulfillment of a safety fi.4nction. The cause of the event was a shorted wire on liquid I ne solenoid valve 0RG053A that caused the solenoid! valve to close, resulting in the compressor shutting down on low suction pressure. The corrective action was to repair the wiring problem and return the compressor to service.

LER 373-2013-008 On November 22, 2013, both Units 1 and 2 were in Mode 1 at 100% power. The 'A' train of Main Control Room ventilation (VC) was inoperable due to an emergent repair of a Freon leak. At 1920 hours0.0222 days <br />0.533 hours <br />0.00317 weeks <br />7.3056e-4 months <br /> CST, the 'B' AEER Cooler Condenser Fan tripped. An acrid smell was detected coming from the fan motor breaker compartment. The 'B' train of VC and VE was declared inoperable. With both trains of VCNE inoperable, this resulted in an event or condition that could have prevented the fulfillment of a safety function. The cause of the event was a winding failure of the 'B' AEER Cooler Condenser fan motor. Corrective actions included replacing the failed fan motor and performing a failure analysis to determine the cause of the winding failure.

Component Failure Data

Manufacturer: Eaton 05000-373 Device: Breaker, A AEER HVAC Return Fan (Model: HFW3125JLY)

Component ID: 1AP80E-B5 YEAR 2022 SEQUENTIAL NUMBER 003 REV NO.

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