05000423/LER-2015-001, Regarding Unlatched Dual Train HELB Door Results in Potential Loss of Safety Function

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Regarding Unlatched Dual Train HELB Door Results in Potential Loss of Safety Function
ML15118A536
Person / Time
Site: Millstone Dominion icon.png
Issue date: 04/20/2015
From: Daugherty J
Dominion, Dominion Nuclear Connecticut
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 15-001-00
Download: ML15118A536 (6)


LER-2015-001, Regarding Unlatched Dual Train HELB Door Results in Potential Loss of Safety Function
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(v), Loss of Safety Function

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)(i)(B), Prohibited by Technical Specifications
4232015001R00 - NRC Website

text

4Domi nioN Dominion Nuclear Connecticut, Inc.

Rope Ferry Rd., Waterford, CT 06385 Mailing Address: P.O. Box 128 Waterford, CT 06385 dom.corn U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 APR 2 0 2015 Serial No.15-180 MPS Lic/GJC RO Docket No.

50-423 License No.

NPF-49 DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 LICENSEE EVENT REPORT 2015-001-00 UNLATCHED DUAL TRAIN HELB DOOR RESULTS IN POTENTIAL LOSS OF SAFETY FUNCTION This letter forwards Licensee Event Report (LER) 2015-001-00 documenting an event that occurred at Millstone Power Station Unit 3 on February 19, 2015. This LER is being submitted pursuant to 10 CFR 50.73(a)(2)(v)(D).

If you have any questions or require additional information, please contact Mr. William D. Bartron at (860) 444-4301.

Sincerely, Site Vice President - Millstone Attachments: 1 Commitments made in this letter: None

~Jf

Serial No.15-180 Docket No. 50-423 Licensee Event Report 2015-001 -00 Page 2 of 2 cc:

U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 R. V. Guzman NRC Project Manager Millstone Units 2 and 3 U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 C-2 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

Serial No.15-180 Docket No. 50-423 Licensee Event Report 2015-001 -00 ATTACHMENT LICENSEE EVENT REPORT 2015-001-00 UNLATCHED DUAL TRAIN HELB DOOR RESULTS IN POTENTIAL LOSS OF SAFETY FUNCTION MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC.

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 0113112017 (02-2014)

  • 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 />.

Reported lessons leamed are incorporated into the licensing process and fed back to industry.

Send comments regarding burden estimate to the FOIA, Privacy and Information Collections

( E )

Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by LICENSEE EVENT REPORT (LER) intemet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and (See Page 2 for required number of Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB digits/characters for each block) control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

3. PAGE Millstone Power Station Unit 3 05000423 1 OF 3
4. TITLE Unlatched Dual Train HELB Door Results in Potential Loss of Safety Function
5. EVENT DATE
6. LER NUMBER
7. REPORT DATE
8. OTHER FACILITIES INVOLVED SFACILITY NAME DOCKET NUMBER MO YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR F

05000 MONTH DY YA YER NUMBER NO.05 0

FACILITY NAME DOCKET NUMBER 02 19 2015 2015-001 00 04 20 2015 05000

9. OPERATING MODE
11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)

[1 20.2201(b)

El 20.2203(a)(3)(i)

[E 50.73(a)(2)(i)(C)

[I 50.73(a)(2)(vii)

[1 20.2201(d)

El 20.2203(a)(3)(ii)

El 50.73(a)(2)(ii)(A)

El 50.73(a)(2)(viii)(A) 1E 20.2203(a)(1)

El 20.2203(a)(4) 0l 50.73(a)(2)(ii)(B)

[I 50.73(a)(2)(viii)(B)

[_1 20.2203(a)(2)(i)

El 50.36(c)(1)(i)(A)

[1 50.73(a)(2)(iii)

E-50.73(a)(2)(ix)(A)

10. POWER LEVEL [E

20.2203(a)(2)(ii)

El 50.36(c)(1)(ii)(A)

[E 50.73(a)(2)(iv)(A)

El 50.73(a)(2)(x)

ID 20.2203(a)(2)(iii)

[E 50.36(c)(2)

El 50.73(a)(2)(v)(A)

El 73.71(a)(4) 10 20.2203(a)(2)(iv)

El 50.46(a)(3)(ii)

El 50.73(a)(2)(v)(B)

El 73.71(a)(5) 1E 20.2203(a)(2)(v)

[1 50.73(a)(2)(i)(A)

El 50.73(a)(2)(v)(C)

El OTHER El 20.2203(a)(2)(vi)

El 50.73(a)(2)(i)(B)

[

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

Specify in Abstract below or in

______________N__C___oNRCForm66A

12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT TELEPHONE NUMBER (Include Area Code)

William D. Bartron, Supervisor Nuclear Station Licensing 1 (860) 444-4301CAUSE SYSTEM COMPONENT MANU-REPORTABLE

CAUSE

SY MANU-REPORTABLE FACTURER TO EPIX C

FACTURER TO EPIX

14. SUPPLEMENTAL REPORT EXPECTED
15. EXPECTED MONTH DAY YEAR SUBMISSION El YES (If yes, complete 15. EXPECTED SUBMISSION DATE)

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

On February 19, 2015, with Millstone Power Station Unit 3 (MPS3) at 100% power and in operating mode 1, an individual on a fire watch rove processed through a dual train high energy line break (HELB) door normally and upon checking the door after passage the individual noted the door did not latch. The Control Room was promptly notified.,

An operator was dispatched to investigate. The operator exercised the door lock-set mechanism freeing the latch allowing the door to properly latch. The door was inoperable for approximately 7 minutes. Technical Specification 3.0.3 was entered and exited appropriately.

Although no definite failure mechanism was identified, the door was experiencing high usage due to compensatory fire watch roves entering/exiting the door. The door lockset mechanism was manually manipulated and then tested several times satisfactorily by maintenance personnel. Further, the door design has the door swing such that the HELB event would act to open the door when the lockset mechanism fails. Engineering is evaluating the adequacy of the preventive maintenance frequency. Additionally, a design change to reverse the door swing such that the HELB event would cause the door to close and thus not rely on the lock-set mechanism is being considered. Additional corrective actions are being taken in accordance with the station's corrective action program.

This event is being reported pursuant to 10 CFR 50.73(a)(2)(v)(D), as a condition that could have prevented the fulfillment of a safety function for systems needed to mitigate the consequences of an accident.

NRC FORM 366 (02-2014)

IRC =

1. EVENT DESCRIPTION

On February 19, 2015, with Millstone Power Station Unit 3 (MPS3) at 100% power and in operating mode 1, an individual on a fire watch rove processed through a dual train high energy line break (HELB) door normally and upon checking the door after passage the individual noted the door did not latch. The Control Room was promptly notified. An operator was dispatched to investigate. The operator exercised the door lock-set mechanism freeing the latch allowing the door to properly latch.

The door was inoperable for approximately 7 minutes. Technical Specification 3.0.3 was entered~and exited appropriately.

This event was reported to the NRC pursuant to 10 CFR 50.72(b)(3)(v)(D), (NRC event 50836) as a condition that could have prevented the fulfillment of a safety function for systems needed to mitigate the consequences of an accident. This event is also being reported pursuant to 10 CFR 50.73(a)(2)(v)(D), as a condition that could have prevented the fulfillment of a safety function for systems needed to mitigate the consequences of an accident.

BACKGROUND:

This door fulfills the requirements of a Security Door, Technical Requirement Manual Fire Door, C02 Door, Dual Train Protection Door, and a HELB Door. It is a key card actuated door with a crash bar on one side and a thumb latch on the other side. The door is part of the HELB barrier for the A and B 480 volt switchgear.

2. CAUSE

Although no definite failure mechanism was identified, the door was experiencing high usage due to compensatory fire watch roves entering/exiting the door. Further the door design has the door swing such that the HELB event would act to open the door when the latch fails.

3. ASSESSMENT OF SAFETY CONSEQUENCES

Given the low likelihood of an Auxiliary Building HELB occurring during the time the door was not properly latched (7 minutes), the consequences of this event was of very low safety significance.

4. CORRECTIVE ACTION

Since this event occurred on the back shift, a maintenance technician was called in to inspect the door lock-set mechanism and affect any necessary repairs. The technician reported his inspection was satisfactory. He exercised the door lock-set mechanism from both the crash bar and the thumb release mechanisms approximately 30 times without any repeat indications of the latch sticking or not functioning. He also noted he tightened one screw on the mechanism that he found loose during this inspection. Continued exercises of the door mechanism after tightening the screw showed no difference in the smooth and proper operation of the door lockset mechanism.

It was identified that the door was experiencing high usage due to compensatory fire watch roves entering/exiting the door. Equipment repairs have been completed eliminating the need for this high frequency fire rove activity. Additionally, the preventive maintenance for the door lock-set mechanism has been changed.

A design change to reverse the door swing such that the HELB event would cause the door to close and thus not rely on the lock-set mechanism is being considered.

Additional corrective actions are being taken in accordance with the station's corrective action program.

5. PREVIOUS OCCURRENCES

MPS3 LER 2014-004-00, Unlatched Dual Train HELB Door Results in Potential Loss of Safety Function.

6. Energy Industry Identification System (EIIS) codes:

Door-DR Switchgear - SWGR