05000423/LER-2014-004, Regarding Unlatched Dual Train HELB Door Results in Potential Loss of Safety Function
| ML15049A294 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 02/09/2015 |
| From: | Daugherty J Dominion, Dominion Nuclear Connecticut |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 15-066 LER 14-004-00 | |
| Download: ML15049A294 (6) | |
| 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 |
| 4232014004R00 - NRC Website | |
text
~Dominion Dominion Nuclear Connecticut, Inc.
Rope Ferry Rd.. Waterford, CT 06385 Mailing Address: P.O. Box 128 Warerford, CT 06385 dom.com FEB 0 9 2015 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Serial No.
MPS Lic/GJC Docket No.
License No.15-066 RO 50-423 NPF-49 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3 LICENSEE EVENT REPORT 2014-004-00 UNLATCHED DUAL TRAIN HELB DOOR RESULTS IN POTENTIAL LOSS OF SAFETY FUNCTION This letter forwards Licensee Event Report (LER) 2014-004-00 documenting two events that occurred at Millstone Power Station Unit 3 on December 12, 2014 and January 15, 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, Joh/R. Daugherty Sit Vice President - Millstone Attachments: 1 Commitments made in this letter: None
Serial No.15-066 Docket No. 50-423 Licensee Event Report 2014-004-00 Page 2 of 2 cc:
U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 M. C. Thadani NRC Project Manager Millstone Units 2 and 3 U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 B-1 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station
Serial No.15-066 Docket No. 50-423 Licensee Event Report 2014-004-00 ATTACHMENT LICENSEE EVENT REPORT 2014-004-00 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: 01/3112017 (02-2014)
(02'2014 "INEstimated 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 learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections LICENSEE ET(LER)
Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by EVENT REPORT intemet e-mail to lnfocollects.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 T
D Y FACILITY NAME DOCKET NUMBER MO A
YEAR N
SEQUENTIAL REV H
DAY YEAR NUMBER NO.
05000 FACILITY NAME DOCKET NUMBER 12 12 201 2014-004
- - 00 02 09 2015 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check al that apply)
[1 20.2201(b)
El 20.2203(a)(3)(i)
F1 50.73(a)(2)(i)(C)
E] 50.73(a)(2)(vii)
El 20.2201(d)
C3 20.2203(a)(3)(ii)
[I 50.73(a)(2)(ii)(A)
E3 50.73(a)(2)(viii)(A)
[1 20.2203(a)(1)
[1 20.2203(a)(4)
[1 50.73(a)(2)(ii)(B)
E3 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
[1 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL F1 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
E3 50.73(a)(2)(iv)(A)
LI 50.73(a)(2)(x)
E3 20.2203(a)(2)(iii)
E3 50.36(c)(2)
LI 50.73(a)(2)(v)(A) 13 73.71(a)(4) 10 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
LI 50.73(a)(2)(v)(B)
EL 73.71(a)(5) 1L 20.2203(a)(2)(v)
[L 50.73(a)(2)(i)(A)
E3 50.73(a)(2)(v)(C) 13 OTHER
[]
20.2203(a)(2)(vi) 13 50.73(a)(2)(i)(B)
[
50.73(a)(2)(v)(D)
SpeciyFinAbstractbetoworin
1. EVENT DESCRIPTION
On December 12, 2014, with Millstone Power Station Unit 3 (MPS3) at 100% power and in operating mode 1, an operator discovered a door for the MPS3 East Motor Control Center Rod Control area would not latch upon exit from the room. Upon discovery of the door not properly latching, the door was declared non-functional. Since this door is a dual train High Energy Line Break (HELB) boundary door, it affected the operability of both trains of 480 volt safety related switch gear. Plant Technical Specification (TS) 3.0.3 was entered. The latching mechanism was manually manipulated and lubricated by maintenance personnel. Proper operation of the door was restored within 35 minutes of being identified not functioning properly and TS 3.0.3 was exited. This door was then tested over a dozen times without failure.
On January 15, 2015, with MPS3 at 100% power and in operating mode 1, an individual processed through the door normally and upon checking the door after passage the worker noted the door did not latch. The Control Room was promptly notified. The door was repaired and retested satisfactorily. The door was inoperable for approximately 19 minutes. TS 3.0.3 was entered and exited appropriately.
These events were reported to the NRC pursuant to 10 CFR 50.72(b)(3)(D), (NRC event 50676 and 50737 respectively) as a condition that could have prevented the fulfillment of a safety function for systems needed to mitigate the consequences of an accident. These events are 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, CO 2 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
The door passage mechanism consists of a crash bar on one side of the door and a lockset thumb piece, connected to the latch mechanism in the lockset, on the other side. Utilizing the thumb piece/crash bar causes the lock-set latch to retract into the lockset, unlocking the latch from behind the strike. When the strike is activated by the personnel security key card, the strike releases the latch. Personnel are then required to simply push the door open. Once the door is opened, the strike resets to its original locked position. The door then closes and latches. The door is now locked in the closed position preventing the door from opening. After the door is unlocked utilizing the security key card, if personnel accessing the door use the crash bar or the thumb piece to open the door, instead of simply pushing the door open, the lockset latch sometimes retracts far enough into the lockset to jam inside the lockset and fails to return to its normal position, behind the strike, thus leaving the door unlatched. The use of the crash bar/thumb piece is intended for emergency use only and not intended for normal passage.
Although no definite failure mechanism was identified, there have been several occasions where a security door Iockset has been jammed due to usage of the emergency use only door hardware (crash bar/thumb piece).
3. ASSESSMENT OF SAFETY CONSEQUENCES
Given the low likelihood of an Auxiliary Building HELB occurring during either time the door was not properly latched (35 minutes on December 12, 2014 and 19 minutes on January 15, 2015), the consequences of these events are of very low safety significance.
4. CORRECTIVE ACTION
In both cases the door latching mechanism was manually manipulated and lubricated by maintenance personnel. The door was then tested several times satisfactorily. Additional inspection did not find any additional foreign material in the lockset mechanism.
Additionally, management has issued a special communication to remind plant personnel that security doors should only be pushed or pulled and not to use the crash bar or door thumb piece/knob/lever except for an emergency. Additional corrective actions are being taken in accordance with the station's corrective action program.
5. PREVIOUS OCCURRENCES
MPS2 2011-005-00, Enclosure Building Rendered Inoperable Due to Degraded Door Seal.