DCL-24-054, LCO 3.0.3 Completion Time Limits

LCO 3.0.3 Completion Time Limits

ML24141A032
Person / Time
Site:	Diablo Canyon
Issue date:	05/17/2024
From:	Rogers J Pacific Gas & Electric Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
DCL-24-054 LER 2024-001-00
Download: ML24141A032 (1)

Text

Pac ific Gas and Electric Company ""

Justin E. Rogers Diablo Ca nyon Powor Plant Sta tion Direc tor Mail code 104151502 P.O. Bo x 56 Avila Bea c h, CA 93424

805.545.3088 Ju stin.Rogers@ pge.c o m

PG&E Letter DCL-24-054

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Docket No. 50-323, OL-DPR-82 Diablo Canyon Power Plant, Unit 2 Unit 2 Licensee Event Report 2024-001-00, Unit 2 LCO 3.0.3 Completion Time Limits

Dear Commissioners and Staff,

In accordance with the requirements of 10 CFR 50. 73(a)(2)(i)(B), Pacific Gas and Electric Company (PG&E) hereby submits the enclosed Diablo Canyon Power Plant (DCPP) Unit 2 Licensee Event Report.

PG&E makes no new or revised regulatory commitments (as defined by NEI 99-04) in this report. Corrective actions identified in this letter will be implemented in accordance with the DCPP Corrective Action Program.

This event did not adversely affect the health and safety of the public.

If you have any questions or require additional information, please contact Mr. James Morris, Regulatory Services Manager, at (805) 545-4609.

Sincerely,

Justin E. Rogers r -z-'1 Date

dqmg/ 51229466-7 Enclosure Diablo Distribution Mahdi 0. Hayes, NRC Sen ior Resident Inspector INPO Samson S. Lee, NRC Senior Project Manager John D. Monninger, NRC Region IV Administrator

A m e mber of th e STAR S Allia n ce Callaway

• Dia blo Ca n yo n

• Pa lo Verd e

• Wo lf Creek NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 04/30/2027 (04-02-2 024) Estimated burden per response to co m ply 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

/~,~**"*"<,\\ LICENSEE EV ENT REPORT (L E R) learned a re incolJ)Oraled Into the licensing process and fed back to industry. Send comments rega rding burden estimate lo the FOIA, Libra,y, and lnlonnation Collections Branch (T-6 A10M), U. S. Nuclear Regulato,y ts/characters for each b lock) Commission, Washington, DC 20555-0001, o r by email to lnfocollects.R esource@nrc.gov, a nd the 0MB reviewer

\\~~ ~ ~l (See Pag e 2 for required number of digi..... (S ee NURE G-1 022, R. 3 fo r a l: 0MB Office of Information and Regulalo,y Affairs, (3150-0104), Attn: Desk Officer for the Nuclea r Regulalo,y instructio n a nd guida n ce for co mpleting this fo rm Commission, 72517th Slniet NW, W as hington, DC 20503. The NRC may n o t co n duct o r sponsor, and a person Is bt1p*/l'lf<ff'!!..nr1, gQ~teadlag -anil:lQC * !.Ql l ecl l Q sl Ur:llg~/slaff/scl Q22/.Q/) not required lo respond to, a collection o f infonnation unless the documen t requesting or requinng the collection displays a cunrenUy valid 0MB control numbe r.

1. Facility Name ~ 050 2. Docket Number 3. Page Diablo Canyon Power Plant, Unit 2 052 00323 1 OF 4

4. Title LCO 3.0.3 Completion Time Limits

5. Event Dale 6. LER Number 7. Report Dale B. Other Facllltles Involved

Month Da y Year Year Sequ ential Revision Month Day Ye a r Fa cility Nam e Doc ket Number Numb er No. 050

03 19 2024 2024 - 001 - 00 05 20 24 Facility Name 052 Doc ket Numb er

9. Operating Mode 110. Power Level 1 100

11. This Report is Submitted Pursuant to the Requirements of 10 CFR §: (Check all that apply) 10 CFR Part 20 20.2203(a)(2)(vi) 10 CFR Part 50 50. 73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 73.1200(a) 20.2201(b) 20.2203(a)(3)(i) 50.36( c)(1 )(i)(A) 50. 73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 73.1200(b) 20.2201(d) 20.2203(a)(3)(ii) 50.36(c)(1 )(ii)(A) 50.73(a)(2)(iii) 50. 73(a)(2)(ix)(A) 73.1200(c) 20.2203(a)(1) 20.2203(a)(4) 50.36(c)(2) 50. 73(a)(2)(iv)(A) 50.73(a)(2)(x) 73.1200(d) 20.2203(a)(2)(i) 10 CFR Part 21 50.46(a)(3)(ii) 50. 73(a)(2)(v)(A) 10 CFR Part 73 73.1200(e) 20.2203(a)(2)(ii) 21.2(c) 50.69(9) 50.73(a)(2)(v)(B) 73. 77(a)(1) 73.1200(f) 20.2203(a)(2)(iii) 50. 73(a)(2)(i)(A) 50.73(a)(2)(v)(C) 73.77(a)(2)(i) 73. 1200(9) 20.2203(a)(2)(iv) ~ 50. 73(a)(2)(i)(B) 50. 73(a)(2)(v)(D) 73. 77(a)(2)(ii) 73.1200(h) 20.2203(a)(2)(v) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii)

OTHER (Specify here, in abstr a ct, or NRG 366A).

12. Licensee Contact for this LER Licensee Contact Phone Number (Include area code)

David Madsen 805-545-6192

13. Complete One Line fo r each Component Failure Described in this Report

Cause System Component Manufacturer Reportable to IRIS Cause System Component Manufacturer Reportable to IRIS

X ED BKR N/A Yes

14. Supplemental Report Expected Month Da y Ye a r

15. Expected Submission Date

~ ID No Y es (If yes, complete 15. Ex pe c te d Submission Da te)

16. Abstract (Limit to 13 26 spaces, I.e., a pprox imately 13 single-space d ty pewr itten lines)

On March 19, 2024, Pacific Gas and Electric Company requested, and the Nuclear Regulatory Commission (NRC) verbally granted, additional time to resolve a maintenance issue affecting an exhaust fan associated with the Auxiliary Building Ventilation System (ABVS) due to its redundant exhaust fan being concurrently inoperable. The cause of the inoperable redundant ABVS fan was elevated temperature on the "C" Phase between the contactor and the breaker.

The additional time granted by the NRC allowed Diablo Canyon Power Plant ma intenance personnel to perform needed maintenance and restore the exhaust fan to operable on March 19, 2024. As required by NUREG - 1022, exceedance of Technical Specification completion times are still required to be reported per 50.73(a)(2)(i)(B), even though be ing granted enforcement discretion. There was no impact to the health and safety of the public or plant personnel.

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150- 0104 EXPIRES: 04/30/2027 (04-02-2024) Estim a ted bu rden per respo n se to comp ly w ith this m a n da tory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learn ed a re inco rporated into the licensing process an d fed back to indus try. Send co m me nts LIC ENSE E EVENT REPORT (LER) rega rding b u rden estimate to the FOIA, Library, and Information Collectio n s Branch (T-6 A10M), U.S.

Nu clear Reg ula to ry Co m mission, W as hington, DC 20555-00 01, or by em ail to CONTINUATION SHEET lnfocollects.Resource@ nr c. gov, and the 0 MB reviewer al: 0MB Office of Info rma tion and Regulato ry Affairs, (3150-0104), Attn: Desk Officer for lhe Nu clea r Regula to ry Commission, 725 17th Street NW,

(See NUR EG-1022, R.3 for instruc tion a nd guida n c e for com p leting this form W as hington, DC 20503. The NRC ma y nol con duc t o r spo n sor, and a pe rso n Is no t requ ired to http://www.nrc.gov/read lng-rm /do c -co llections/nuregs/s ta ff/sr1022/r3/) respond to, a collection of In form ation u n less the docu m en t requ estin g o r requ iring lhe collection displays a cu rrently valid 0M B con trol number.

~- - ---- - --~~ 1. FACILITY NAME r-, 2. DOCKET NUMBER 3. LER NUMBER Diablo Canyon Power Plant, Unit 2 050 YEAR SEQUENTIAL REV I 00-323 NUMBER NO, I 052 ~-, 001 1-0

NARRATIVE

I. Reporting Requ irements

This event is being reported in accordance with 10 CFR 50. 73(a)(2)(i)(B) and the associated guidance of NUREG-1022, Rev ision 3, as a condition prohibited by Technical Specifications (TS). The total time that Auxi liary Bu ilding Ventilation System (ABVS) was inoperable exceeded the tota l time allowed per Diablo Canyon Power Plant (DCPP) TS 3.0.3.

II. Plant Cond itions

At the time of the event, DCPP Unit 2 was in Mode 1 at 100 percent power.

Ill. Problem Description

A. Background

The ons ite power systems cons ist of all sources of electric power and their associated distribution systems within the DCPP. Included are the main generators, emergency diesel generators (EOG), and the Class 1 E and non-Class 1 E station batteries.

!The ABVS provides all outside air supply for the auxiliary building under all operating conditions. It also serves its primary purpose of providing cooling air for the engineered safety features pump motors. The fans for the system receive power

~rom the Class 1 E 480-V buses. The supply system consists of two full capacity fans (each powered _ from a separate Class 1 E bus). The exhaust system consists of two full capacity fans (each powered from a separate Class 1 E bus).

~BVS exhaust fans' functions are to limit the maximum ambient temperature in rooms containing safety related equipment, and during accident conditions to provide for conta inment excess pressure relief and min imize radioactivity released via the plant vent.

B. Event Description

On March 19, 2024, Pacific Gas and Electric Company (PG&E) requested, and the Nuclear Regulatory Commission (NRC) verbally granted, additional time to resolve a maintenance issue affecting an exhaust fan associated with the ABVS due to its redundant exhaust fan being concurrently inoperable.

The additional time allowed DCPP maintenance personnel to perform needed maintenance and restore an exhaust fan to operable (note that an exhaust fan remained in service and available), thereby preventing an otherwise unnecessary down-power or the shutdown of Unit 2 without a corresponding health and safety benefit. As requ ired by NUREG-1022, the exceedance of TS completion times are still required to be reported per 50.73(a)(2)( i)(B),even though being granted enforcement discretion. A discussion of this occurence is provided below:

NR C FOR M 366A (04-02-2024 ) Page 2 of 4 NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 04/30/2027 (04-02-2024) Estimated b u rden per respo n se to co m ply with this mandatory colleclion request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lesso n s learne d a re inco rporated Into the licensing process and fed back to indu stry. Send comme nts LIC E NS EE EV ENT R EPORT ( LE R) regarding b ur den estim ate to the FO IA, Libra ry, and Information Collections Branch (T-6 A10M), U. S.

Nu clear Reg u lato ry Co mm ission, Was hin gton, DC 20555-0001, or by em ail to CONTINUATION SH EET lnfocollects.Reso u rce@nrc.gov, and lhe 0 MB reviewer a t: 0 MB Office of Information and Reg ulato ry Affairs, (3150-0104), Attn: Desk Officer fo r the Nucl ea r Regula tory Co mm ission, 725 17th Street NW,

(See NUR EG-1022, R.3 for in struc tion and guidan c e for c omp leting this fo rm W as hin gton, DC 20503. The NRC m a y no t conduct o r sponso r, a nd a person is no t requ ired to http://www.nrc.gov/read ing-rm/doc-colleclions/nuregs/staff/sr 1022/r3/) respo n d lo, a collection of information unl ess lhe do cu men t requesting or requiring the collection displays a cu rrently valid 0MB contro l num b er.

.--- ------- ------,~ 1. FACILITY NAME 2. DOCKET NUMBER 3. LER NUMBER Diablo Canyon Power Plant, Unit 2 050 YEAR SEQUENTIAL REV I 00-323 NUMBER NO. I 052 ~ -, 001 1-0

NARRATIVE

B. Event Description (continued)

On March 18, 2024, during planned maintenance of EDG 2-2, ABVS exhaust fan E-1 tripped on thermal overload (TOL).

Following reset and investigation of the TOL condition, fan E-1 was declared inoperable at 19:43 Pacific Daylight Time (PDT). Fan E-1 was not restored within four hours, and therefore in accordance w ith the provisions of TS 3.8.1 Required

~ction 8.2, ABVS exhaust fan E-2 (which was supported by EDG 2-2) was declared inoperable at 23:43 on the same day.

TS 3. 7.12 for ABVS does not describe a Required Action for two inoperable ABVS trains, and TS 3.0.3 was entered.

DCPP personnel determined that the add itional repairs necessary to restore ABVS fan E-1 would exceed the TS 3.0.3 LCO completion times and requested enforcement discretion. Verbal enforcement discretion was granted by the NRC on March 19, 2024, at 05:36 PDT, which allowed an add itional period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to restore an ABVS fan to operab le condition. Fan E-1 was restored to operab ility at 17:30 on March 19, 2024, and the applicable TS Conditions were exited.

There was no impact to the health and safety of the public or plant personnel.

C. Status of Inoperable Structures, Systems, or Components that Contributed to the Event

EDG 2-2, ABVS Fan E-1, and ABVS Fan E-2 are discussed above.

rrhere were no other structure, system, or component failures associated with this event.

D. Method of Discovery

Self-Revealing.

E. Operator Actions

Operations pe rsonnel responded to the trip of ABVS exhaust fan E-1 in accordance with plant procedures. Although declared inoperable in accordance with TS, exhaust fan E-2 rema ined available and in service.

NR C FOR M 366A (0 4-02-2 024 ) Page 3 of 4 NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 04/30/2027 (04 -0 2-2024) Estim a ted bu rden per response to comp ly w ith this ma n da tory collection reque st: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learned ar e in co rpo rated Into the licensing process an d fed back to indus1ry. Se n d com ments LIC E NS EE EVENT R E PORT (L E R) rega rding b ur den estimate to lhe FOIA, Lib ra ry, and Informatio n Collections Branch { T-6 A10M), U. S.

Nu clea r Reg u lato ry Commission, Was hington, DC 20555-0001, or by em ail to CONTINUATION SHE ET lnfocollecls.Reso u rce@nrc. gov, and the 0M B reviewer al: 0MB Office of lnformalion and Re gu lato ry Affairs, (3150-0104), Attn : Desk Officer fo r lhe Nuc lear Regulatory Co mmi ssion, 7251 7th Street NW, (S e e NUREG - 1022, R.3 for instruction a nd g uidan ce for completing this form Wa shingto n, DC 20503. The NRC m a y not conducl o r sponsor, a nd a person is not requ ired lo http://www.nrc.gov/readjng-rm/doc-collect ions/nuregs/staff/sr1022/r3/) respond to, a collection of info rmallon u nless the docum en t req u esting o r requiring the collection displays a cur renlly valid 0MB con lro l n um ber.

1. FACILITY NAME 2. DOCKET NUMBER 3. LER NUMBER Diablo Canyon Power Plant, Unit 2 050 YEAR SEQUENTIAL REV I 00 -323 I NUMBER NO.

052 [ 2024 l-1 001 1-G

NARRATIVE

F. Safety System Responses

There were no safety system responses related to this event.

IV. Cause o f the Problem

The cause of the ABVS fan failure E-1 was a degraded "C" phase contactor in the breaker cubicle providing power to the

~an.

V. Assessment of Safety Consequences

There were no safety consequences as a result of this event.

VI. Corrective Actions

The immediate corrective action was to implement repairs in the breaker cubicle providing power to ABVS Fan E-1.

Operations declared E-1 operable at 1730 PDT on March 19, 2024. Additional follow-up corrective actions will be managed in accordance with the DCPP Corrective Action Program.

IVII. Additional Information

rrhere have been no similar events at DCPP in the previous three years.

NR G FOR M 366A (04-02 -2024) Page 4 of 4