05000423/LER-2017-001, Regarding Loss of Safety Function - Secondary Containment

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Regarding Loss of Safety Function - Secondary Containment
ML17087A265
Person / Time
Site: Millstone Dominion icon.png
Issue date: 03/20/2017
From: Daugherty J
Dominion Nuclear Connecticut
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 17-001-00
Download: ML17087A265 (5)


LER-2017-001, Regarding Loss of Safety Function - Secondary Containment
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
4232017001R00 - NRC Website

text

Dominion Nuclear Connecticut, Inc.

Rope Ferry Rd., Waterford, CT 06385 Mailing Address: P.O. Box 128 Waterford, CT 06385 dom.com U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 LICENSEE EVENT REPORT 2017-001-00 MAR 2 0 2017 Serial No.

MPS Lic/TGC Docket No.

License No.17-051 RO 50-423 NPF-49 LOSS OF SAFETY FUNCTION-SECONDARY CONTAINMENT This letter forwards Licensee Event Report (LER) 2017-001-00 documenting a condition discovered at Millstone Power Station Unit 3, on January 20, 2017. This LER is being submitted pursuant to 1 OCFR50.73(a)(2)(v)(C) as a condition that could have prevented the fulfillment of a safety function for systems or structures to control the release of radioactive material, and 10CFR50.73(a)(2)(v)(D) to mitigate the consequences of an accident.

If you have any questions or require additional information, please contact Mr. Jeffry A.

Langan at (860) 444-5544.

Sincerely, Joa~

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

cc:

U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd.

Suite 100 King of Prussia, PA 19406-2713 R.V. Guzman Serial No.17-051 Docket No. 50-423 Licensee Event Report 2017-001-00 Page 2 of 2 NRC Senior Project Manager Millstone Units 2 and 3 U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 C-2 Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

L ATTACHMENT Serial No.17-051 Docket No. 50-423 Licensee Event Report 2017-001-00 LICENSEE EVENT REPORT 2017-001-00 LOSS OF SAFETY FUNCTION-SECONDARY CONTAINMENT MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC.

NRC FORM 366 U.S *. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 1013112018 (11-2015)

, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.

1.. FACILITY NAME

2. DOCKET NUMBER
3. PAGE Millstone Power Station Unit 3 05000423 1 OF 2
4. TITLE Loss of Safety Function - Secondary Containment
5. EVENT DATE
6. LER NUMBER
7. REPORT DATE
8. OTHER FACILITIES INVOLVED YEAR
  • 1 SEQUENTIAL I *REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.

MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 01 20 2017 2017 -

001 - 00 03 20 2017 05000

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

D 20.2201(bl D 20.2203(a)(3)(il D 50.73(a)(2)(i)(C)

D 50.73(a)(2)(vii) 1 D 20.2201 (dl D 20.2203(a)(3)(iil D 50.73(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(A)

D 20.2203(a)(1)

D 20.2203(a)(4l D 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(viii)(B)

D 20.2203(a)(2)(il D 50.36(c)(1 )(i)(A)

D 50.73(a)(2)(iii)

D 50.73(a)(2)(ix)(A)

10. POWER LEVEL D 20.2203(a)(2)(iil D 50.36(c)(1 )(ii)(A)

D 50.73(a)(2)(iv)(A)

D 50.73(a)(2)(x)

D 20.2203(a)(2)(iiil D 50.36(c)(2)

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

D 13.11(a)(4l D 20.2203(a)(2)(iv)

D 50.46(a)(3)(ii)

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

D 13.11(a)(s) 100 D 20.2203(a)(2)(v)

D 50.73(a)(2)(i)(A)

[gJ D OTHER 50.73(a)(2)(v)(C)

D 20.2203(a)(2)(vi)

D 50.73(a)(2)(i)(B)

[gJ 50.73(a)(2)(v)(D)

Specify in Abstract below or in

1. EVENT DESCRIPTION

6. LER NUMBER I

SEQUENTIAL I NUMBER 001 REV NO.

00 2

3. PAGE OF At 0835 on January 20, 2017 while operating in MODE 1 at 100% power, a door in the auxiliary building at Millstone Power Station Unit 3 failed to fully close following personnel passage due to the failure of the mechanical door closer mechanism. This door is part of the secondary containment boundary which must be intact for the supplemental leak collection release system (SLCRS) to perform its safety function. Operators determined that the condition of the door rendered secondary containment inoperable and resulted in a condition that oould have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material and mitigate the consequences of an accident. The door was repaired and the door completely closed at 1256 on January 20, 2017. This condition is being reported under 10 CFR 50. 73(a)(2)(v)(C) and 10 CFR 50. 73(a)(2)(v)(D).

2. CAUSE

The cause of the door to not fully close was the mechanical failure of the door closing mechanism such that it prevented the door to close automatically o~ be closed manually.

3. ASSESSMENT OF SAFETY CONSEQUENCES

2 SLCRS is designed to mitigate the radiological consequences of postulated accidents by filtering the exhaust air from the secondary containment. SLCRS is comprised of two redundant trains of exhaust fans and filter units. The safety function of SLCRS is to maintain a negative pressure in the secondary containment to ensure there is no unfiltered leakage to the outside environment from these areas in the event of a loss of coolant accident (other than those releases assumed in the' design basis dose calculations).

With the door stuck open, the ability for SLCRS to achieve negative pressure was impacted.

The actual reactor containment building allowable leakage (La) is much lower than that assumed in the design basis analysis. This difference provides additional margin to the design basis analysis.

4. CORRECTIVE ACTION

The door closing mechanism was replaced and secondary containment was dedared operable at

- 1256 on January 20, 2017. Additional corrective actions will be taken in accordance with the corrective action program.

5. PREVIOUS OCCURRENCES

There are no previous occurrences with the same underlying reason or consequences.

6. ENERGY INDUSTRY IDENTIFICATION SYSTEM (EllS) CODES:

Auxiliary Building - NF SLCRS-VF, VG, VH Secondary Containment-NH Door-DR NRC FO_RM 366A (11-2015)