05000336/LER-2011-005, Regarding Enclosure Building Rendered Inoperable Due to Degraded Door Seal

Regarding Enclosure Building Rendered Inoperable Due to Degraded Door Seal

ML12039A107
Person / Time
Site:	Millstone
Issue date:	01/30/2012
From:	Scace S Dominion Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 11-005-00
Download: ML12039A107 (5)

LER-2011-005, Regarding Enclosure Building Rendered Inoperable Due to Degraded Door Seal

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
LER closed by
IR 05000245/2012003 (23 July 2012)
3362011005R00 - NRC Website

text

Dominion Dominion Nuclear Connecticut, Inc.

Millstone Power Station Rope Ferry Road Waterford, CT 06385 JAN 30 2012 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Serial No.

MPS Lic/TGC Docket No.

License No.12-002 RO 50-336 DPR-65 DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 2 LICENSEE EVENT REPORT 2011-005-00 MILLSTONE POWER STATION UNIT 2 ENCLOSURE BUILDING RENDERED INOPERABLE DUE TO DEGRADED DOOR SEAL This letter forwards Licensee Event Report (LER) 2011-005-00 documenting a condition discovered at Millstone Power Station Unit 2 on December 3, 2011. This LER is being submitted pursuant to 10 CFR 50.73(a)(2)(v)(C) as a condition that could have prevented the fulfillment of the safety function of structures or systems to control the release of radioactive material.

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

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

Serial No.12-002 Docket No. 50-336 Licensee Event Report 2011-005-00 Page 2 of 2 cc:

U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406-1415 C. J. Sanders Project Manager - Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08B3 Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

Serial No.12-002 Docket No. 50-336 Licensee Event Report 2011-005-00 ATTACHMENT LICENSEE EVENT REPORT 2011-005-00 MILLSTONE POWER STATION UNIT 2 DOMINION NUCLEAR CONNECTICUT, INC.

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10/2010)

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

3. PAGE Millstone Power Station - Unit 2 05000336 1 OF 2

4. TITLE Enclosure Building Rendered Inoperable Due to Degraded Door Seal

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED FACILITY NAME DOCKET NUMBER SEQUENTIAL REV MONTH DAY YEAR 05000 MONTH DAY YEAR YEAR NUMBER NO.

FACILITY NAME DOCKET NUMBER 12 03 2011 2011 - 005- 00 01 30 2012 05000

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR

.heck all that apply) 9.OPRAIN MDE--20.2201 (b) 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii) 20.2201_(d) 20.2203(a)(3)(ii)(A 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2203(a)(1 )

20.2203(a)(4) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.36(c)(1)(i)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x)

10. POWER LEVEL 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(B) 73.71 (a)(5) 100 20.2203(a)(2)(v) 50.73(a)(2)(i)(A)

X 50.73(a)(2)(v)(C)

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

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

Specify in Abstract below or in

1.

Event Description

At 1230 on December 3, 2011, with Millstone Power Station Unit 2 (MPS2) operating at 100 percent power in Mode 1, the control room was notified that a door sweep became dislodged on a door credited as a boundary door for the Enclosure Building (EB) (door 205-(-25)-001). Operators declared the door inoperable and entered the Action for plant Technical Specification (TS) 3.6.5.2 Enclosure Building at 1235. TS 3.6.5.2 Action requires that the EB be restored to operable status with 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in Cold Shutdown within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. Repairs to the door were completed and operators exited the Action at 1524 on December 3, 2011. The last known time where the door sweep was not dislodged was within 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br /> of the time of discovery.

The operability of the EB ensures that the release of radioactive materials from the primary containment atmosphere will be restricted to those leakage paths and associated leak rates assumed in the accident analyses.

TS Surveillance Requirement (SR) 4.6.5.2.2 stipulates that the Enclosure Building Filtration Train produces a negative pressure of greater than or equal to 1/4 inches water gauge (wg) in the Enclosure Building Filtration Region within 1 minute after an EBF Actuation Signal. When the door sweep dislodged, it created an opening estimated as 3/4 inch by 36 inches (27 square inches). Since there is currently no bounding analysis on the impact of this size opening on the ability of the Emergency Building Filtration System (EBFS)[BD] to produce the required negative pressure, the EB was declared inoperable.

This condition is being reported pursuant to 10 CFR 50.73(a)(2)(v)(C) as an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material.

2.

Cause

The direct cause of the door seal failure was that the mounting hardware (screws) loosened and fell out. The apparent cause is the door was not being properly maintained.

3.

Assessment of Safety Consequences

The safety consequences of this event were low. The door was repaired within three hours of discovery and within 21 hours2.430556e-4 days <br />0.00583 hours <br />3.472222e-5 weeks <br />7.9905e-6 months <br /> of the last known operable condition. The safety function of the EBFS is to control and monitor radioactive releases from Containment and Emergency Core Cooling Systems (ECCS) leaks in the event of a Loss of Coolant Accident (LOCA). Operability of the EBFS is necessary to ensure doses to the public and control room operators do not exceed 10 CFR 50.67 limits in the event of a design basis LOCA. This function is achieved when EBFS is operational by maintaining a required negative pressure of 1/4 inches wg. It is not credited for any other design basis accidents.

Reactor coolant radioactivity levels were normal (significantly less than Technical Specification limits). Based on a review of effluent and containment radiation monitors, there was no indication of abnormal Reactor Coolant System, containment or ECCS leakage. Based on these conditions, there were no adverse consequences to the health and safety of the public or the plant and its personnel resulting from this EB boundary breach.

4.

Corrective Action

The door was repaired. Doors that are part of the Enclosure Building boundary have been added to the preventive maintenance program.

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

5.

Previous Occurrences

LER 2011-001-00 "Enclosure Building Rendered Inoperable Due to Dislodged Bushings" describes a condition at MPS2 where the EBFS was not able to meet the acceptance criteria of a negative pressure of greater than or equal to 1/4 inch wg. The direct cause for not meeting the Enclosure Building drawdown acceptance criteria was that sliding bushings on the main steam safety valves exhaust piping had dislodged and not reseated.

Energy Industry Identification System (EIIS) codes are identified in the text as [XX].

I