05000461/LER-2018-005-01, Unplanned Reactor Scram During Maintenance Outage Due to High Intermediate Range Monitor Flux

Unplanned Reactor Scram During Maintenance Outage Due to High Intermediate Range Monitor Flux

ML19079A156
Person / Time
Site:	Clinton
Issue date:	03/05/2019
From:	Stoner T Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
U-604473 LER 2018-005-01
Download: ML19079A156 (4)

LER-2018-005, Unplanned Reactor Scram During Maintenance Outage Due to High Intermediate Range Monitor Flux

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i)
4612018005R01 - NRC Website

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~ Exelon Ge.neration Clinton Power Station 8401 Power Road Clinton, IL 61727 U-604473 March 5, 2019 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 ":, _

Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461 Subject: Licensee Event Report 2018-005-01 10 CFR 50.73 SRRS 5A.108 Encloseq is Licensee Event Report (LER) 2018-005-01: Unplanned Reactor Scram During Maintenance Outage Due to High Intermediate Range Monitor Flux. This is a supplemental report to LER 2018-005-00 submitted to the NRC on December 21, 2018.. The updated information in the LER is denoted by revision bars located in the right-hand margin. This report is being submitted in accordance with the requirements of 1 O CFR 50.73.

There are no regulatory commitments contained in this report.

Should you have any questions concerning this report, please contact Mr. Dale Shelton, Regulatory Assurance Manager, at (217) 937-2800.

Respectfully, Theodore R. Stoner Site Vice President Clinton Power Station

Attachment:

Licensee Event Report 2018-005-01 cc:

Regional Administrator - Region Ill NRC Senior Resident Inspector - Clinton Power Station Office of Nuclear Facility Safety - Illinois Emergency Management Agency 0

0

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NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY*OMB: NO. 3150-0104 EXPIRES: 03/31/2020 (04*2018)

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

3.Page Clinton Power Station, Unit 1 05000461 1

OF 3

4. Title Unplanned Reactor Scram During Maintenance Outage Due to High Intermediate Range Monitor Flux

5. Event Date

6. LER Number

7. Report Date

8. Other Facilities Involved I

Sequential I Rev Facility Name Docket Number

- Month Day Year Year Number No.

Month Day Year 05000 Facility Name Docket Number 10 28 2018 2018 -

005 01 03 05 2019 05000

9. Operating Mode

11. This Report is Submitte~ Pursuant to the Requirements of 10 CFR §: (Check all that apply}

D 20.2201(b)

D 20.2203(a)(3)(i)

D 50.73(a)(2)(ii)(A)

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

D 20.2201(d)

D 20.2203(a)(3)(ii)

D 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(viii)(B) 3 D

D D

D 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)

D 20.2203(a)(2)(i)

D 50.36( c)( 1 )(i)(A)

~ 50.73(a)(2)(iv)(A)

D 50.73(a)(2)(x)

10. Power Level D 20.2203(a)(2)(ii)

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 50.36(c)(2)

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

D 73.71 (a)(5)

D 20.2203(a)(2)(iv)

D 50.46(a)(3)(ii)

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

D 13.77(aH1i 001 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)(i) *.

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)

D Other (Specify in Abstract below or in C.

Cause of the Event

YEAR 2018 -

SEQUENTIAL NUMBER 005 The root cause of this event was that procedure pressure control guidance was not adequate to address the cooldown rate conditions during a soft shutdown.

D.

Safety Consequences

REV NO.

01 This event is reportable in accordance with 10 CFR 50.73{a)(2){iv)(A) as "any event or condition that resulted in the manual or automatic actuation of the Reactor Protection System."

The scram caused by increased flux to the IRMs involved no safety consequences or failures of plant equipment. The condition of the reactor core at the time of the event was stable: Systems necessary to maintain the plant per Technical Specification requirements following the automatic plant trip performed as expected and remained available to perform their safety function.

E.

Corrective Actions

As an interim corrective action, following the reactor scram, Procedure 3006.01, Unit Shutdown, was revised to include Appendix F, Plant Shutdown Briefing Topics, specific to performance of a soft shutdown. The procedure revision indicates that soft shutdowns are prohibited until further notice and it prohibits forced cool down until all control rods are fully inserted.

Further corrective actions to be taken include revising Procedure 3006.01 to implement best practices for pressure control strategies, abort criteria based on reactor pressure, and actions to minimize time in the region of vulnerability. Associated operator training will be updated to incorporate the procedure changes and lessons learned from this event.

F.

Previous Similar Occurrences There were no previous events identified involving a low power RPS actuation similar to the occurrence described in this licensee event report.

~~ G.

Component Failure Data

There were no failed components associated with this event. Page _3_ of _3_