05000285/LER-2013-018, Regarding Postulated Fire Event Could Result in Shorts Impacting Safe Shutdown

Regarding Postulated Fire Event Could Result in Shorts Impacting Safe Shutdown

ML13361A218
Person / Time
Site:	Fort Calhoun
Issue date:	12/26/2013
From:	Cortopassi L Omaha Public Power District
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LIC-13-0185 LER 13-018-00
Download: ML13361A218 (4)

LER-2013-018, Regarding Postulated Fire Event Could Result in Shorts Impacting Safe Shutdown

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(8) 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ii)
2852013018R00 - NRC Website

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jjjjjjjj Omaha Public Power Olslrlct 444 South 16th Street Mall Omaha, NE 68102-2247 LlC-13-0185 December 26,2013 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

Reference:

Docket No. 50-285

Subject:

Licensee Event Report 2013-018, Revision 0, for the Fort Calhoun Station Please find attached Licensee Event Report 2013-018, Revision O. This report is being submitted pursuant to 10 CFR 50.73(a)(2)(ii)(8). There are no new commitments being made in this letter.

If you should have any questions, please contact Terrence W. Simpkin, Manager, Site Regulatory Assurance, at (402) 533-6263.

Louis P. Cortopassi Site Vice President and CNO LPC/epm Attachment c:

M. L. Dapas, NRC Regional Administrator, Region IV J. M. Sebrosky, NRC Senior Project Manager J. C. Kirkland, NRC Senior Resident Inspector L. E. Wilkins, NRC Project Manager Employment wit" Equal Opportunity

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150*0104 EXpiRES: 10131/2013 (10-2010)

, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information collection.

13. PAGE Fort Calhoun Station 05000285 1 OF 3

4. TITLE Postulated Fire Event Could Result in Shorts Impacting Safe Shutdown

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.

MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 10 28 2013 2013 018 -

0 12 26 2013 05000

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check a/l that apply)

D 20.2201(b) o 20.2203(a)(3)(i)

D 50.73(a)(2)(i)(C)

D 50.73(a)(2)(vii) 5 D

20.2201 (d)

D 20.2203(a)(3)(ii) o 50.73(a)(2)(ii)(A) o 50.73(a)(2)(viii)(A) o 20.2203(a)(1) o 20.2203(a)(4)

~ 50.73(a)(2)(ii)(B) o 50.73(a)(2)(viii)(B)

D 20.2203(a)(2)(i) o 50.36(c)(1 )(i)(A) o 50.73(a)(2)(iii) o 50.73(a)(2)(ix)(A)

10. POWER LEVEL D

20.2203(a)(2)(ii) o 50.36(c)(1)(ii)(A) o 50.73(a)(2)(iv)(A) o 50.73(a)(2)(x)

D 20.2203(a)(2)(iii)

D 50.36(c)(2) o 50.73(a)(2)(v)(A) o 73.71(a)(4) 0 D

20.2203(a)(2)(iv) o 50.46(a)(3)(iI) o 50.73(a)(2)(v)(B) o 73.71(a)(5) o 20.2203(a)(2)(v) o 50.73(a)(2)(i)(A) o 50.73(a)(2)(v)(C) o OTHER o 20.2203(a)(2)(vi) o 50.73(a)(2)(i)(B) o 50.73(a)(2)(v)(O)

12. LICENSEE CONTACT FOR THIS LER FACILITY NAME f

ELEPHONE NUMBER (Include AleS Code)

Erick Matzke 402-533-6855 CAUSE SYSTEM COMPONENT MANU-REPORTABLE

CAUSE

SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPIX FACTURER TO EPIX

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR DYES (If yes, complete 15. EXPECTED SUBMISSION DATE)

~NO SUBMISSION DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)

On October 9, 2013, an event notification applicable to Callaway Nuclear Power Plant was posted that documented a postulated fire event regarding the impact of unfused direct current (DC) ammeter circuits in the control room (CR). In the postulated event, a fire in the CR could cause one of the ammeter wires to short to the ground plane. Simultaneously, if the fire causes another DC wire from the opposite polarity on the same battery to also short to the ground plane, a ground loop would be established through the unprotected ammeter wiring. This event could result in excessive current flow (heating) in the ammeter wiring to the point of causing a secondary fire in the raceway system. The secondary fire could adversely affect safe shutdown equipment and potentially result in the loss of the ability to conduct a safe shutdown as required by 10 CFR50 Appendix R. Plant engineering personnel reviewed the information against station electrical schematics and at approximately 1230 CDT on October 28, 2013, an 8-hour notification was made pursuant to 10 FR 50.72(b)(3)(ii)(8). The station was in Mode 5 when the condition was identified.

An hourly fire watch was established in the affected locations of the station. FCS will install fuses in the DC ammeter circuitry as determined by Engineering Change 62826, Add Fuses to the DC Ammeter Circuitry for Ammeters.

NRC FORM 366 (10-2010)

BACKGROUND

2. DOCKET YEAR 05000285 2013

6. LER NUMBER

3. PAGE 2

OF J

SEQUENTIAL I REV NUMBER NO.

018 o

Fort Calhoun Station (FCS) is a two-loop reactor coolant system of Combustion Engineering (CE) design.

EVENT DESCRIPTION

On October 9,2013, an event notification applicable to Callaway Nuclear Power Plant was posted that documented a postulated fire event regarding the impact of unfused direct current (DC) ammeter circuits in the control room (CR). In the postulated event, a fire in the CR could cause one of the ammeter wires to short to the ground plane. Simultaneously, if the fire causes another DC wire from the opposite polarity on the same battery to also short to the ground plane, a ground loop would be established through the unprotected ammeter wiring. This event could result in excessive current flow (heating) in the ammeter wiring to the pOint of causing a secondary fire in the raceway system.

The secondary fire could adversely affect safe shutdown equipment and potentially result in the loss of the ability to conduct a safe shutdown as required by 10 CFR50 Appendix R.

Plant engineering personnel reviewed the information against station electrical schematics and at approximately 1230 COT on October 28, 2013, an 8-hour notification was made to the Headquarters Operations Office under 10 FR 50.72(b)(3)(ii)(B), any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety (Event Number 49478). The station was in Mode 5 when the condition was identified. This report is being submitted pursuant to 10 CFR 50.73(a)(2)(ii), any event or condition that resulted in: (B) the nuclear power plant being in an unanalyzed condition that significantly degraded plant safety.

CONCLUSION The short vulnerabilities described in this report have existed since the original design and installation of the DC ammeter circuitry at FCS.

CORRECTIVE ACTIONS

An hourly fire watch was established in the Control Room, Cable Spreading Room, Switchgear Rooms, and Air Compressor Room as a compensatory action for this postulated fire event. The fire watch will be maintained until completion of Engineering Change (EC) 62826, Add Fuses to the DC Ammeter Circuitry for Ammeters.

FCS will install fuses in the DC ammeter circuitry as determined by EC 62826.

SAFETY SIGNIFICANCE

A fire in the Control Room could cause ammeter wires to short to the ground plane. This would cause a ground loop through the unprotected ammeter wiring to the point of causing a secondary fire in the raceway system. The secondary fire could cause the loss of the ability to conduct a safe shutdown as required by 10 CFR 50 Appendix R.

SAFETY SYSTEM FUNCTIONAL FAILURE This does not represent a safety system functional failure in accordance with NEI 99-02, Revision 7 PREVIOUS EVENTS None 3. PAGE 3

OF 3