05000389/LER-2024-003, Unplanned Reactor Scram

Unplanned Reactor Scram

ML24218A080
Person / Time
Site:	Saint Lucie
Issue date:	08/05/2024
From:	Rasmus P Florida Power & Light Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
L-2024-115 LER 2024-03-00
Download: ML24218A080 (1)

LER-2024-003, Unplanned Reactor Scram

Event date:
Report date:
3892024003R00 - NRC Website

text

August 5, 2024 L-2024-115 10 CFR 50.73

U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

Re: St. Lucie Unit 2 Docket No. 50-389 Reportable Event: 2024-03-00 Date of Event: June 4, 2024

Unplanned Reactor Scram

The attached Licensee Event Report, 2024-03, is being submitted pursuant to the requirements of 10 CFR 50 .73 to provide notification of the subject event.

Should you have any questions regarding this submission, please contact Mr. Kenneth Mack, Senior Manager Licensing and Reg Compliance - Nuclear Fleet, at 561-904-3635.

This letter contains no new or modified regulatory commitments.

Sincerely,

Paul Rasmus General Manager - Regulatory Affairs - Nuclear Fleet Florida Power & Light Company

Attachment

cc: St. Lucie NRC Senior Resident Inspector St. Lucie Station NRC Program Manager

Florida Power & Light Company

6501 S. Oc ea n Driv e, Jen se n Be ac h, FL 34957 NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 04/30/2027 (04-02-2024) Estimated burden per re sponse to comply with this mand atory 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

c,V'all.lf '°(., learned are in cOl])orated into the fi cens ing process an d fed back to industry. Se nd comments regarding burden

.. 'i\\ LICENSEE EVENT REPORT (LER) estimate to th e FOIA, Library, and lnfonnation Collections Branch {T-6 A 101'1), U. S. Nucl ea" Regulatory

!~ j \\. / ..... (See NUREG-1022, (See Page 2 for required number of digits/characters for each block) Commission, Washington, DC 20555-0001, or by email to lnfocollects.Re source@nrc.gov, and the 0MB reviewer at 0MB Office or lnfonnation and Regulatory Affai rs, (3150-0104), Attn: Desk Office r for th e Nudear Reg ul atory R.3 for instruction and guidance for completing this form Commission, 725 17th Stree t NW, Washington, DC 20503. The NRC may not conduct or spo ns or, and a perso n is b!ti;r11www me gold~adiag-[rn/doc-collec!ioas/au[egs/s!a~[1 Q22l[JQ not required to respond to , a collection of infonnation unless the doc ument requesting or requiring the collection displays a currently va id 0MB control number.

1. Facility Name ~ 050 2. Docket Number 3. Page

St. Lucie Unit 2 D 052 00389 1 OF 2

4. Title

Unplanned Reactor Scram

5. Event Date 6. LER Number 7. Report Date 8. Other Facilities Involved

Month Day Year Year Sequential Revision Month Day Year Facility Name D Docket Number Number No. 050

06 04 2024 2024 - 03 - 00 8 5 2024 Faciilty Name D 052 Docket Number

9. Operating Mode rO. Power Level 1 92

11. This Report is Sub,nitted Pursuant to the Requirements of 10 CFR §: (Check all that apply)

10 CFR Part 20 D 20.2203(a)(2)(vi) 10 CFR Part 50 D 50. 73(a)(2)(ii)(A) D 50.73(a)(2)(viii)(A) D 73.1200(a)

D 20.2201(b) D 20.2203(a)(3)(i) D 50.36(c)(1 )(i)(A) D 50.73(a)(2)(ii)(B) D 50. 73(a)(2)(viii)(B) D 73.1200(b)

D 20.2201(d) D 20.2203(a)(3)(ii) D 50.36(c)(1 )(ii)(A) D 50.73(a)(2)(iii) D 50. 73(a)(2)(ix)(A) D 73.1200(c)

D 20.2203(a)(1) D 20.2203(a)(4) D 50.36(c)(2) [l] 50.73(a)(2)(iv)(A) D 50. 73(a)(2)(x) D 73.1200(d)

D 20.2203(a)(2)(i) 1 O CFR Part 21 D 50.46(a)(3)(11) D 50.73(a)(2)(v)(A) 10 CFR Part 73 D 73.1200(e)

D 20.2203(a)(2)(ii) D 21.2(c) D 50.69(g) D 50. 73(a)(2)(v)(B) D 73.77(a)(1) D 73.1200(f)

D 20.2203(a)(2)(iii) D 50. 73(a)(2)(i)(A) D 50. 73(a)(2)(v)(C) D 73.77(a)(2)(i) D 73.1200(9)

D 20.2203(a)(2)(iv) D 50. 73(a)(2)(i)(B) D 50. 73(a)(2)(v)(D) D 73.77(a)(2)(11) D 73.1200(h)

D 20.2203(a)(2)(v) D 50. 73(a)(2)(i)(C) D 50. 73(a)(2)(vii)

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

12. Licensee Contact for this LER

Licensee Contact Phone Number (Include area code)

Bob Murrell 319-651-9496

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

Cause System Component Manufacturer Reportable to IRIS Cause System Component Manufacturer Reportable to IRIS B NN IEF N/A y

14. Supplemental Report Expected Month Day Year

15. Expected Submission Date

[l] No Yes (If yes, complete 15. Expected Submission Date) D

16. Abstract (Limit to 1326 spaces, i.e., approximately 13 single-spaced typewritten lines)

On June 4, 2024, at 1352 EDT, while in Mode 1 with Unit 2 at 92 percent power, the reactor was manually tripped due to a loss of condenser vacuum resulting from a circulating water pump (CWP) trip. The circulating water pump (282) trip was caused by the inability of the interlock circuit to provide the inhibiting function from the condenser outlet motor operated valve limit switch auxiliary contact. There were no Systems, Structures, or Components that were inoperable at the start of the event that contributed to the event. This event is being reported pursuant of 10 CFR 50.73(a)(2)(iv)(A), System Actuation.

NRC FORM 366A U.S. NUCLEAR REGU LATORY COMMISSION APPROVED BY 0MB  : NO . 3150 -0104 EXPIRES: 04/30/2027 (04-02-2024) Estimated burden per re spon se to comply with this mandatory collection request: 80 hours. Reported lessons learned are incorporated into the licensing process and fed back to industry . Send comments LIC E NSEE EV ENT REPORT (L ER ) regarding burden estimate to the FOIA, Li brary, and Information Co ll ections Branch (T-6 A1 0M) , U.S .

Nuclear Regulatory Commiss ion, Washington, DC 20555-0001, or by email to CONTINUATION SH EE T lnfocollects.Resource@nrc.go v, and the 0MB reviewer at: 0MB Office of Information and Reg ulatory Affairs, (3150-0104), Attn: Desk Officer for the Nuclear Regulatory Com miss ion, 725 17th Street NW, (See NUREG - 1022, R.3 for instructi on and gu idance for completing th is form Was hi ng ton , DC 20503. The NRG may not conduct or sponsor, and a pe rson is not req uired to http  ://www nrc gov/reading -rm/doc-collections/nuregs/ staff/sr1022/r3D respond to, a co ll ecti on of in fo rm ation unless th e document req uesting or requiring th e collection displays a cu rrently valid 0MB co ntrol number.

1. FACILITY NAME 050 2. DOCKET NUMBER 3. LER NUMBER YEAR SEQUENTIAL REV 1st. L ucie Unit 2 I 00389 D NUMBER NO.

I~ 052 I ~ - , 03 1-0

NARRATIVE

Description of Event:

On June 4, 2024 , at 1352 EDT, while in Mode 1 with Unit 2 at 92 percent power , the reactor was manually tripped d ue to a loss of condenser vacuum resulting from a circulating wate r pump (CWP) trip. There were no Systems, Structures, or Components that were inoperable at the start of the event that contributed to the event. This event is being reported pu rsuant of 10 CFR 50 . 73(a)(2)(iv)(A) , System Actuation.

• Cause of Event:

On June4 , 2024 , at 1345 EDT , St. Lucie Uni t 2 expe rienced a malfu nct ion of the condense r outlet valve (MV-21-5A2) limit sw itch. The ma lfunction resul ted in a trip of the 282 CWP that requ ired a manual reactor trip due to low condenser vacuum .

The 282 CWP trip was caused by the inability of the interlock circui t to prov ide the inh i bit ing fu nctio n f rom the condenser outlet motor operated valve limit switch auxiliary contac t. The lim it switch for the valves a re aux iliary contacts that do not provide indicat ion to the Control Room .

Safety Sign ificance  :

This event did not prevent any safety systems from performing the i r safety related functions based on the m i ni mal amount of leakage identified.

Th is Licensee Event Report is being reported pursuant of 10 CFR 50 .73(a)(2)(iv)(A), System Actuation.

Th is event did not result in a Safety System Functional Failure .

Correct ive Actions  :

Operating procedu res we re revised to requ i re the re m oval of control fuses from the CWP breaker.

Simila r Events  :

A rev iew of events over the past 5 years did not identify any unplanned reactor scrams as a result of a CWP trip.

N RC FORM 366 A (04-02-202 4) Page 2 of 2