05000373/LER-2013-001, Regarding Secondary Containment Inoperable Due to Interlock Doors Open

Regarding Secondary Containment Inoperable Due to Interlock Doors Open

ML13119A108
Person / Time
Site:	LaSalle
Issue date:	04/26/2013
From:	Vinyard H Exelon Generation Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
RA13-027 LER 13-001-00
Download: ML13119A108 (4)

LER-2013-001, Regarding Secondary Containment Inoperable Due to Interlock Doors Open

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function 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)(B) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown
3732013001R00 - NRC Website

text

10 CFR 50.73 RA1 3-027 April 26, 2013 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 LaSalle County Station, Units 1 and 2 Facility Operating License Nos. NPF-1 1 and NPF-18 NRC Docket Nos. 50-373 and 50-374

Subject:

Licensee Event Report 2013-001-00 Secondary Containment Inoperable Due to Interlock Doors Open In accordance with 10 CFR 50.73(a)(2)(v)(C) and (D), Exelon Generation Company (EGC), LLC, is submitting Licensee Event Report Number 2013-001-00 for LaSalle Units 1 and 2.

There are no regulatory commitments in this letter. Should you have any questions concerning this report, please contact Mr. Guy V. Ford, Regulatory Assurance Manager, at (815) 415-2800.

Harold T. Vinyard Plant Manager LaSalle County Station

Enclosure:

Licensee Event Report cc:

Regional Administrator - NRC Region III NRC Senior Resident Inspector - LaSalle County Station

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO, 3150-0104 EXPIRES: 10/31/2013 (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.

3. PAGE LaSalle County Station, Unit 1 05000373 1

OF 3 TITLE Secondary Containment Inoperable Due to Interlock Doors Open

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REV NO.

MONTH DAY YEAR FACILITY NAME LaSalle County Station, Unit 2 DOCKET NUMBER 05000374 FACILITY NAME DOCKET NUMBER 02 28 2013 2013 001 00 04 26 2013 N/A N/A

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) q 20.2201(b) q 20.2203(a)(3)(i) q 50.73(aX2Xi)(C) q 50.73(a)(2)(vii) 1 q 20.2201(d) q 20.2203(a)(3)(ii) q 50.73(a)(2)(ii)(A) q 50.73(a)(2XviiiXA) q 20.2203(a)(1) q 20.2203(a)(4) q 50.73(ax2)(i1XB) q 50.73(a)(2)(viii)(B) q 20.2203(aX2)(i) q 50.36(c)(1)(i)(A) q 50.73(ax2)(iii) q 50.73(a)(2)(ix)(A)

10. POWER LEVEL q 20.2203(a)(2)(ii) q 50.36(c)(1)(iiXA) q 50.73(aX2Xiv)(A) q 50.73(a)(2)(x) q 20.2203(a)(2)(iii) q 50.36(c)(2) q 50.73(a)(2)(vXA) q 73.71(a)(4) 100 q 20.2203(a)(2)(iv) q 50.46(a)(3)(ii) q 50.73(a)(2)(vXB) q 73.71(a)(5) q 20.2203(a)(2)(v) q 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C) q OTHER q 20.2203(a)(2)(vi) q 50.73(a)(2X1)(B) 50.73(a)(2)(vXD)

Specify in Abstract below or in Completion Time to restore the secondary containment to operable status allowed by TS 3.6.4.1 Required Action A.1 E.

CORRECTIVE ACTIONS

The interlock assembly for door #226 was repaired.

Periodic preventative maintenance will be performed on secondary containment airlock doors to inspect fasteners and tighten or replace as necessary.

A more robust design for the interlock assembly will be identified, procured and installed for the subject secondary containment airlock doors.

F.

PREVIOUS OCCURRENCES

LER 2012-001-00 On September 18, 2012, Units 1 and 2 were in Mode 1 at 100% power. At 0115 hours0.00133 days <br />0.0319 hours <br />1.901455e-4 weeks <br />4.37575e-5 months <br /> CDT, an Equipment Operator (EO) reported the Unit 2 Reactor Building 761'elevation Interlock Doors 424/314 were both open at the same time for approximately 10 seconds. During the time that both interlock doors were open, Technical Specification (TS) Surveillance Requirement (SR) 3.6.4.1.2 ("Verify one secondary containment access door in each access opening is closed") was not met. The secondary containment was declared INOPERABLE for the time that both interlock doors were open. LaSalle Station entered and exited TS 3.6.4.1 Required Action A.1 for both Units 1 and 2 to restore secondary containment to OPERABLE status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

The cause of the event was determined to be the solenoid bracket being loose on Unit 2 Reactor Building 761' interlock door 424. Two screws that hold the locking solenoid bracket in place were found loose. The two loose screws on the locking solenoid mounting bracket caused the electric lock assembly to become misaligned. The misalignment of the electric lock assembly prohibited the locking solenoid plunger from being fully engaged with the door catch and damaged the limit switch, which resulted in the capability to open both interlock doors at the same time.

This occurrence was similar to the most recent event. In addition to repairing the interlock assembly by tightening the fasteners, actions were initiated to periodically inspect the assemblies and to identify and install a more robust design. However, the due dates for these actions were not aggressive enough to prevent this occurrence.

LER 2011-003-00 On March 2, 2011, Unit 1 was in Mode 1 at 100% power and Unit 2 was in Mode 5 in a refueling outage, with fuel moves in progress. At 0928 hours0.0107 days <br />0.258 hours <br />0.00153 weeks <br />3.53104e-4 months <br /> CST, the Unit 1 Reactor Operator reported that the control room indication for secondary containment [NG] vacuum was 0.17 inch of vacuum water gauge.

The cause of the event could not be determined; however, it is suspected that both Unit 2 steam tunnel airlock doors were simultaneously opened and held open to transport material during outage demobilization activities.

G.

COMPONENT FAILURE DATA

Locknetics/SDC style lock