05000483/LER-2020-001, Emergency Exhaust Train Inoperable Due to Fan Belt Degradation and Failure

Emergency Exhaust Train Inoperable Due to Fan Belt Degradation and Failure

ML20108F546
Person / Time
Site:	Callaway
Issue date:	04/17/2020
From:	Bianco F Ameren Missouri, Union Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
ULNRC-06574 LER 2020-001-00
Download: ML20108F546 (7)

LER-2020-001, Emergency Exhaust Train Inoperable Due to Fan Belt Degradation and Failure

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(i)
4832020001R00 - NRC Website

text

r Ameren MISSOURI Callaway Plant April 17, 2020 ULNRC-06574 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 10 CFR 5073 Ladies and Gentlemen:

DOCKET NUMEER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.

RENEWED FACILITY OPERATING LICENSE NPF-30 LICENSEE EVENT REPORT 2020-001-00 EMERGENCY EXHAUST INOPERABLE DUE TO FAN BELT DEGRADATION AND FAILURE The enclosed Licensee Event Report is submitted in accordance with 50.73(a)(2)(i)(B), 50.73(a)(2)(v)(C), and 50.73(a)(2)(v)(D), to report the inoperability of the B train Emergency Exhaust System due to fan belt degradation and failure, resulting in an operation or condition prohibited by Technical Specifications and a condition that could have prevented fulfillment of a safety function.

If you have any questions concerning this LER, please contact Tom Elwood, Supervising Engineer, Regulatory Affairs and Licensing at (314) 225-1905.

Sincerely, Frederick J. Bianco Senior Director, Nuclear Operations

Enclosure:

LER 2020-001-00 8315 County Ioad 459 Steedinan, IVIO 65077 A.rnerenl\\4issouri.corn J

a

ULNRC-06574 April 17, 2020 Page 2 of 3 cc:

Mr. Scott Morris Regional Administrator U. S. Nuclear Regulatory Commission Region IV 1600 East Lamar Boulevard Arlington, TX 7601 1-45 1 1 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. L. John Kios Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 09E3 Washington, DC 20555-000 1 1

L i

ULNRC-06574 April 17, 2020 Page 3 of 3 Index and send hardcopy to QA File A160.0761 Hardcopy:

Certrec Corporation 6100 Western Place, Suite 1050 Fort Worth, TX 76107 (Certrec receives ALL attachments as long as they are non-safeguards and may be publicly disclosed.)

Electronic distribution for the following can be made via LER ULNRC Distribution:

F. M. Diya B. L. Cox F. J. Bianco S. P. Banker R. C. Wink T. B. Elwood K. A. Mills J.C. Sellers Corporate Oversight NSRB Secretary Performance Improvement Coordinator STARS Regulatory Affairs Mr. Jay Silberg (Pillsbury Winthrop Shaw Pittman LLP)

Missouri Public Service Commission

NRC FORM 366 US. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2017)

Estimated burden per response to comply 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 />.

LICENSEE EVENT REPORT LER Reported lessons arned are incorporated into the licensing process and fed back to industry.

I Send comments regarding burden estimate to the Information Services Branch (T-2 F43),

U.S.

/

(See Page 2 for required number of digits/characters for each block)

Nuclear Regulatory Commission, Washington, DC 20555-0001 or by e-mail to Infocollects.

Resourcenrc.gov, and to the Desk

Officer, Office of Information and Regulatory

Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503.

If a means (See NUREG-1022, R.3 for instruction and guidance for completing this form used to impose an information collection does not display a currently valid 0MB control number, http://www.nrc.gov/reading-rm/doc-collections/nuregs/staft/srl 022!r3/)

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

3. PAGE CallawayPlantUniti 05000483 i of 4

4. TITLE Emeraencv ExhauF Train Inonerable Due o Fan Belt flearada on and Failure

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED SEQUENTIAL FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 02 18 2020 2020

- 001

- 000 05000 9.OPERA11NG MODE

11. THIS REPORT IS SUBMITrED PURSUANT TOTHE REQUIREMENTS OF 10 CFR §: (Check all that app(y) 1

20.2201(b) 20.2203(a)(3)(i) j 50.73(a)(2)(ii)(A) 5073(a)(2)(viii)(A)

C 20.2201(d)

J 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 0 20.2203(a)(1)

Q 20.2203(a)(4)

D 50.73(a)(2)(iii)

LI 50.73(a)(2)(ix)(A) 0 20.2203(a)(2)(i)

D 50.36(c)(1)(i)(A) 0 50.73(a)(2)(iv)(A)

E 50.73(a)(2)(x)

10. POWER LEVEL Q 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A)

D 50.73(a)(2)(v)(A) 1 73.71(a)(4) 20.2203(a)(2)(iii) 50.36(c)(2)

C 50.73(a)(2)(v)(B) 73.71(a)(5) 1 00%

20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C) 73.77(a)(1)

E 20.2203(a)(2)(v)

E 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(D)

D 73.77(a)(2)(i)

E 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B)

E 50.73(a)(2)(vH) 0 73.77(a)(2)(ii) 50.73(a)(2)(i)(C)

OTHER Specify in Abstract below or in NRC Form 366A

12. LICENSEE CONTACT FOR THIS LER JCENSEE CONTACT TELEPHONE NUMBER (IncludeArea Code)

TB. Elwood, Supervising Engineer, Regulatory Affairs and Licensing 314-225-1905 ia COMPLETE ONE LINE FOR EACH COMPONENT FIaJLURE DESCRIBED INTHIS REPORT

CAUSE

SYSTEM COMPONENT FACTURER REPORTABLE

CAUSE

SYSTEM COMPONENT FACTURER REPORTABLE

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR YES (ffyes, complete 15. EXPECTED SUBMISSION DATE)

D NO SUBrSSION 09 01 2020 BSTRACT (Limitto 1400 spaces, i.e., approximately 15 single-spaced typewritten fines)

Dn February 1 8, 2020, one of the two fan belts on the fan unit for the B train of the Emergency Exhaust System (EES) was liscovered to be broken. Following replacement of the fan belts on February 22, 2020, it was identified on February 24, 2020 that the fan belts had not been properly tensioned. Based on assessment of these identified conditions, it was letermined that the EES B train was inoperable from June 25, 2019 to February 26, 2020 due to degraded/nonconforming an belts. During this time, the B train of the Emergency Exhaust System would not have been capable of pertorming its 3afety function for its required 30-day mission time in the event of an accident. The plant was operating in Mode 1

, and fuel iandling operations involving irradiated fuel assemblies were performed during the period that the B train of emergency xhaust was inoperable.

nvestigation into the root cause and development of corrective actions for the event reported in this LER were impeded by mplementation of COVID-19 pandemic countermeasures. A supplementto this LER will be submitted when this nformation is available.

1.

DESCRIPTION OF STRUCTURE(S), SYSTEM(S) AND COMPONENT(S):

Ehe event reported in this LER involves the Emergency Exhaust System (EES). The EES (EIIS: VF) serves both the auxiliary building and the fuel building. Following a safety injection signal (515), safety related dampers isolate the auxiliary building, and the EES filters and exhausts potentially contaminated air due to leakage from ECCS systems. The EES is also designed to filter airborne radioactive particulates from the area of the spent fuel pool following a fuel handling accident.

Fhe EES consists of two independent and redundant trains. Each train consists of a heater, a prefilter, a high efficiency Darticulate air (HEPA) filter bank, an activated charcoal adsorber section for removal of gaseous activity (principally adioiodines), and a fan. Ductwork, dampers, and instrumentation also form part of the system. A second bank of HEPA ilters follows the adsorber section to collect carbon fines.

Fhe EES is on standby for an automatic start following receipt of a fuel building ventilation isolation signal (FBVIS) or a Bafety injection signal (SIS). Initiation of the 515 mode of operation takes precedence over any other mode of operation.

In the 515 mode, the system is aligned to exhaust the auxiliary building.

Fechnical Specification (TS) 3.7.13, Emergency Exhaust System (EES), provides the Limiting Condition for Operation (LCO), Required Actions and Surveillance Requirements for the EES.

2.

INITIAL PLANT CONDITIONS

At the time of the event, Callaway was operating in Mode 1.

3.

EVENT DESCRIPTION

Dn February 18, 2020, the Primary Operations Technician, a nonlicensed operator, reported that one of the two belts on he CGGO2B Emergency Exhaust fan (EIIS FAN) was broken. The second belt was visually verified to still be intact and nstalled on the sheaves. The Shift Manager was notified, and CGGO2B was declared inoperable, Condition A of Fechnical Specification 3.7.13 was entered forthe inoperable EES B train.

During the performance of the as-found inspection, the inner belt was discovered lying on the bottom of the belt guard and appeared to have undergone a tensile break. No evidence of long term wear of the belt was observed, and no foreign material was identified in the belt guard or around the v-belt drive. A work history search confirmed the belts had been replaced on June 25, 201 9, and that the belts had approximately 1 0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of run-time prior to the failure. Since the mission time for the EES is 30 days, failure of the belt after 1 0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of run time is contrary to the capability of the EES B 0 meet its 30-day mission time requirement. This vulnerability existed throughout the time period from when the belts vere replaced on June 25, 2019 to when they were again replaced on February 22, 2020. Following replacement of the belts on Saturday February 22, 2020 the unit was returned to service at 1 3:05 that same day.

\\fter discovery of the belt failure and subsequent replacement of the belts, as described above, an additional condition vas identified on February 24, 2020 from discussion with the maintenance supervisor who oversaw the belt replacement.

rhe new/additional condition was based on the supervisors observation that following replacement of the outer belt, the belt tension appeared to have relaxed as the fan continued to operate, a new task was added to the belt replacement job 0 check belt tension. The as-found tension values of both belts were measured and found to be outside of the acceptance Criteria established in the job. A corrective action document was written to document the inadequate belt tensions, and the EES B train was again declared inoperable on February 24, 2020 at 19:23. Adjustments to the v-belttension and drive alignment were made under the new tasks added to the belt replacement job. The motor sheave was replaced with a Page 2 of 4

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5.

REPORTING REQUIREMENTS

This LER is submitted pursuant to 50.73(a)(2)(i)(B) as an operation or condition prohibited by Technical Specifications.

Additionally, this LER is submitted pursuant to 50.73(a)(2)(v)(C) and 50.73(a)(2)(v)(D) as a condition that would have prevented fulfillment of a safety function.

Fechnical Specification (TS) LCO 3.7.13 requires two trains of the Emergency Exhaust System (EES) to be OPERABLE or the Safety Injection Signal (515) mode of operation during Modes 1, 2, 3, and 4, and during the movement of irradiated uel assemblies in the fuel building.

Fhe EES B train was inoperable for a duration of approximately 246 days. During this period of inoperability, the plant was Dperating in Mode 1. With one EES train inoperable, Required Action A.1 of TS 3.7.13 requires restoring the EES train to DPERABLE status within 7 days. With the Completion Time of Required Action A.1 not met, Required Actions C.1 and 0.2 of TS 3.7.13 require the plant be in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The condition reported in his LER represents an operation or condition not in compliance with the restoration and shutdown Completion Times of Fechnical Specification 3.7.13.

dditionally, during December of 201 9, a fuel handling campaign was performed in the fuel building. Movement of rradiated fuel assemblies in the fuel building is a specified condition of applicability for TS 3.7.13. With the Required ction and Completion Time of Condition A not met during movement of irradiated fuel assemblies in the fuel building, Required Actions D.1 and D.2 require either the OPERABLE EES train to be placed in FBVIS mode or the movement of rradiated fuel assemblies in the fuel building to be immediately suspended. Due to the unknown inoperability of the EES F rain atthe time ofthe fuel handling campaign, the requirements of Conditions D.1 and D.2 of TS 3.7.13 were not met iuring the movement of irradiated fuel assemblies in the fuel building.

Fhe EES performs a function that reduces the post-accident release of radioactive material and mitigates the Donsequences of an accident. The EES B train was inoperable from June 25, 2019 to February 26, 2020. A review of york history for the EES A train identified that it was concurrently out of service for three hours and six minutes for in-place ilter testing on February 1 2, 2020. Therefore, on February 1 2, 2020, both trains of emergency exhaust were unavailable.

Fhis represents a condition that would have prevented the fulfillment of a safety function.

Based on the above, this event is being reported as an operation or condition prohibited by Technical Specifications in accordance with 50.73(a)(2)(i)(B) and as a condition that would have prevented fulfillment of a safety function in accordance with 50.73(a)(2)(v)(C) and 50. 73(a)(2)(v)(D).

6.

CAUSEOFTHE EVENT:

The root cause investigation for this event has been delayed by the COVID-19 pandemic countermeasures. A supplemental Licensee Event Report will be submitted upon completion of the investigation. The supplement LER will also include the EPIX information in Section 13 ofthe LER form.

7.

CORRECTIVE ACTIONS

The root cause investigation and determination of corrective actions for this event have been delayed by the COVID-19 pandemic countermeasures. A supplemental Licensee Event Report will be submitted upon completion of the investigation and determination of the corrective actions.

The B train Emergency Exhaust fan belts have been replaced, and enhancements were implemented for the post-maintenance testing performed following the belt replacement. Both trains of emergency exhaust are OPERABLE, and Callaway is in compliance with Technical Specifications.

8.

PREVIOUS SIMILAR EVENTS

A review of LERs from the past three years for Callaway found no other events involving broken fan belts on fans required by Technical Specifications.