05000410/LER-2012-001, Forced Shutdown Due to an Increase in Drywell Leakage in Excess of Technical Specifications Limit

Forced Shutdown Due to an Increase in Drywell Leakage in Excess of Technical Specifications Limit

ML12046A609
Person / Time
Site:	Nine Mile Point
Issue date:	02/07/2012
From:	Philippon M Constellation Energy Group, EDF Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 12-001-0
Download: ML12046A609 (7)

LER-2012-001, Forced Shutdown Due to an Increase in Drywell Leakage in Excess of Technical Specifications Limit

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
4102012001R00 - NRC Website

text

Michel A. Philippon P.O. Box 63 Plant General Manager Lycoming, New York 13093 315.349.5205 315.349.1321 Fax CENG a joint venture of 0 Constellation Enrm i

O NeDF NINE MILE POINT NUCLEAR STATION February 7, 2012 U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 ATTENTION:

Document Control Desk

SUBJECT:

Nine Mile Point Nuclear Station Unit No. 2; Docket No. 50-410 Licensee Event Report 2012-001, Forced Shutdown Due to an Increase in Drywell Leakage in Excess of Technical Specifications Limit In accordance with 10 CFR 50.73(a)(2)(i)(A), please find attached Licensee Event Report 2012-001, Forced Shutdown Due to an Increase in Drywell Leakage in Excess of Technical Specifications Limit.

Nine Mile Point Nuclear Station, LLC (NMPNS) is currently completing the evaluation of this event.

Upon completion of this action, NMPNS will submit a supplement to the LER.

Should you have questions regarding the information in this submittal, please contact John J. Dosa, Director Licensing, at (315) 349-5219.

Very truly yours, MAP/BTV

Attachment:

Licensee Event Report 2012-001, Forced Shutdown Due to an Increase in Drywell Leakage in Excess of Technical Specifications Limit cc:

NRC Project Manager NRC Resident Inspector NRC Regional Administrator

ATTACHMENT LICENSEE EVENT REPORT 2012-001 FORCED SHUTDOWN DUE TO AN INCREASE IN DRYWELL LEAKAGE IN EXCESS OF TECHNICAL SPECIFICATIONS LIMIT Nine Mile Point Nuclear Station, LLC February 7, 2012

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 10-20o10)

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

3. PAGE Nine Mile Point Unit 2 05000410 1 of 5

4. TITLE Forced Shutdown Due to an Increase in Drywell Leakage in Excess of Technical Specifications Limit

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR NA NA 12 09 2011 2012 001 0102 07 2012 FACILITY NAME DOCKET NUMBER 12 09 211 202 00 0

0 0

21 NA NA 9, OPERATING MODE

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

[1 20.22013(b)

El 20.2203(a)(3)(i)

El 50.73(a)(2)(i)(C)

[I 50.73(a)(2)(vii) 1E 20.2201 (d)

[I 20.2203(a)(3)(ii)

[I 50.73(a)(2)(ii)(A)

El 50.73(a)(2)(viii)(A)

[I[ 20.2203(a)(1)

El 20.2203(a)(4)

El 50.73(a)(2)(ii)(B)

El 50.73(a)(2)(viii)(B)

10. POWER LEVEL El 20.2203(a)(2)(i)

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

El 50.73(a)(2)(iii)

[I 50.73(a)(2)(ix)(A)

El 20.2203(a)(2)(ii) 0] 50.36(c)(1)(ii)(A)

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

El 50.73(a)(2)(x)

[I 20.2203(a)(2)(iii)

[I 50.36(c)(2)

[I 50.73(a)(2)(v)(A)

El 73.71(a)(4) 100%

[1 20.2203(a)(2)(iv)

El 50.46(a)(3)(ii)

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

El 73.71(a)(5)

El 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A)

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

El OTHER

,[

20.2203(a)(2)(vi)

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

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

Specify in Abstract below or in 2317 -Mode Switch placed in Shutdown. Plant in Mode 3, Hot Shutdown.

12/10/2011 - 1813 - Reactor Operation is Mode 4, Cold Shutdown.

E. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED

None

F. METHOD OF DISCOVERY

On December 9, 2011, at 0908, Operations noted that the containment particulate radiation monitors went into alarm and that RCS unidentified leakage was increasing.

G. MAJOR OPERATOR ACTION:

At 0915, TS 3.4.5 Condition B was entered for RCS unidentified leakage rate increase > 2 gpm within a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period. At 1046, a manual shutdown of NMP2 was initiated.

H. SAFETY SYSTEM RESPONSES:

None. No operational conditions requiring the response of safety systems occurred as a result of this event.

II. CAUSE OF THE EVENT

The cause of this event is failed packing on Reactor Coolant Pump "A" discharge blocking valve 2RCS*MOV18A. This caused the RCS unidentified leakage rate to exceed the TS 3.4.5.limit. The valve stem packing leak likely occurred due to a score in the packing material created by a burr on the valve stem. The burr was potentially created during packing replacement in August 2011 when the plant was shutdown due to high unidentified drywell leakage from the packing of this same valve. In August 2011, while removing the failed packing set, destructive removal of the packing set's carbon bushing was performed. The carbon bushing is designed to be removed using a packing puller and the pre-drilled and tapped holes in the top of the carbon bushing. Due to valve stem mis-alignment, the bushing was pinched in the stuffing box and could not be removed in this manner. Hardened tools, including a machinist's punch and hammer, were used to break apart and remove the bushing. It is believed at this point a burr was created on the valve stem.

NMPNS is currently completing the evaluation of this event to determine the cause, any contributing factors, and any needed corrective actions. Upon completion of the evaluation, NMPNS will submit a supplement to this LER.

This event was entered into the NMPNS corrective action program (Condition Report CR-2011-010906).

Ill. ANALYSIS OF THE EVENT:

This event is reportable in accordance with 10 CFR 50.73 (a)(2)(i)(A), "The completion of any nuclear plant shutdown required by the plant's Technical Specifications."

There were no systems inoperable and no system failures related to this event. There were no actual safety consequences from this event. The leakage was from the blocking valve packing and was not indicative of RCS component wear. The leakage was contained within the drywell. The maximum leakage rate noted during this event was 3.7 gpm, which is within the TS limit of 5 gpm. Even if the packing had catastrophically failed, the leakage would still have been contained within the drywell and the plant would have been capable of reaching a safe shutdown condition. There were no system failures that prevented the safe shutdown of the plant. It is therefore concluded that even if a design basis accident had occurred concurrent with this event, all safety systems would have operated to safely mitigate the event. Based on the above considerations, the safety significance of this event is low, and the event did not pose a threat to the health and safety of the public or plant personnel.

This event does not affect the NRC Regulatory Oversight Process (ROP) Index for Unplanned Scrams because the shutdown did not involve a scram. This event increases the ROP Index for Unplanned Power Changes per 7000 Critical Hours from 1.6 to 2.5.

IV. CORRECTIVE ACTIONS

A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS:

1. Removed burr and polished all high spots on the stem of 2RCS*MOV18A to improve the condition of the sealing surface.

2. Installed modified packing on 2RCS*MOV18A and torqued.

3.

Installed modified packing on 2RCS *MOV 1 8B and torqued, as a precautionary measure.

4.

The packing for similar RCS pump suction blocking valves 2RCS*MOV1OA and 2RCS*MOV1OB were re-torqued.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

1. Revise maintenance procedure to include tools and precautions for proper removal of valve packing.

V. ADDITIONAL INFORMATION

A. FAILED COMPONENTS:

None

B. PREVIOUS LERs ON SIMILAR EVENTS:

There are three similar LERs:

1. NMP2 LER 2011-002. On August 6, 2011, NMPNS identified drywell floor drain leakage exceeding the maximum limits of TS 3.4.5 for unidentified drywell leakage. The cause of the unidentified leakage was determined to be failed packing in a reactor coolant system discharge blocking valve, 2RCS*MOV 1 8A.

The corrective actions included repacking the valve to stop the leakage and re-torquing the packing for the remaining similar valves in the RCS to protect against leakage. The primary cause of the packing failure was determined to be vibration and flow turbulence. This caused the packing to relax and fail on 2RCS*MOV 18A.

2. NMP2 LER 2001-007. On December 15, 2001, NMPNS identified drywell floor drain leakage approaching the maximum limits of TS 3.4.5 for unidentified drywell leakage. The cause of the unidentified leakage was determined to be failed packing in a reactor coolant system discharge blocking valve, 2RCS*MOV18A. The corrective actions included installing modified packing to stop the leakage and re-torquing the packing for the remaining similar valves in the RCS to protect against leakage. The primary cause of the packing failure was determined to be packing ring extrusion into the leak-off port.

3. NMPI LER 2006-001. On June 11, 2006, NMPNS commenced a planned downpower to perform a drywell entry to determine the cause of increased drywell leakage. The source of the increased leakage was determined to be the reactor coolant system drain valve packing. The cause of the packing leak was installation of incorrect packing in March 1997. The packing that was installed did not have the same diameter as the inside diameter of the stuffing box. During the shutdown, NMPNS replaced the packing in the leaking RCS pump drain valve.

C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) COMPONENT FUNCTION IDENTIFIER AND SYSTEM NAME OF EACH COMPONENT OR SYSTEM REFERRED TO IN THIS LER:

COMPONENT IEEE 803 IEEE 805 COMPONENT IDENTIFIER SYSTEM IDENTIFICATION Reactor Coolant Blocking Valves V

AD Reactor Protection System NA JC D. SPECIAL COMMENTS:

None