05000321/LER-2009-002, Regarding MSIV Closed Outside of the Allowable Time Due to Loss of Oil in Actuator

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Regarding MSIV Closed Outside of the Allowable Time Due to Loss of Oil in Actuator
ML091730144
Person / Time
Site: Hatch Southern Nuclear icon.png
Issue date: 06/18/2009
From: Madison D
Southern Nuclear Operating Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-09-0987 LER 09-002-00
Download: ML091730144 (6)
v • d • e


LER-2009-002, Regarding MSIV Closed Outside of the Allowable Time Due to Loss of Oil in Actuator
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
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)(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)(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)(v), Loss of Safety Function
3212009002R00 - NRC Website
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text

Dennis R. Madison Southern Nuclear Vice President - Hatch Operating Company. Inc.

Plant Edwin I. Hatch 11028 Hatch Parkway North Baxley, Georgia 31513 Te19125375859 Fax 9123662077 SOUIHERNA COMPANY June 18, 2009 Docket No.:

50-321 NL-09-0987 U. S. Nuclear Regulatory Commission AnN: Document Control Desk Washington, D. C. 20555*0001 Edwin I. Hatch Nuclear Plant Licensee Event Report MSIV Closed Outside of the Allowable Time Due to Loss of Oil in Actuator Ladies and Gentlemen:

In accordance with the requirements of 10 CFR 50.73(a)(2)(i)(B), Southern Nuclear Operating Company is submitting the enclosed Licensee Event Report (LER) concerning main Stream Isolation Valve closure outside of the allowable time due to a loss of oil in the valve actuator.

This letter contains no NRC commitments. If you have any questions. please advise.

Sincerely, 1l.~yT}~

Vice President - Hatch DRM/MJKJ Enclosure: LER 1-2009-002 cc:

Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Ms. P. M. Marino, Vice President - Engineering RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Mr. L. A. Reyes, Regional Administrator Mr. A. E. Martin, NRR Project Manager - Hatch Mr. J. A. Hickey, Senior Resident Inspector Hatch

APPROVED BY OMB: NO. 3150-0104 EXPIRES: 0813112010 (9-2007)

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

2. DOCKET NUMBER
1. FACILITY NAME
13. PAGE 05000321 1 OF 5 Edwin I. Hatch Nuclear Plant Unit 1
14. TITLE MSIV Closed Outside of the Allowable Time due to Loss of Oil in Actuator
8. OTHER FACILITIES INVOLVED I
7. REPORT DATE
5. EVENT DATE
6. LER NUMBER FACILITY NAME DOCKET NUMBER SEQUENTIAL REV MONTH DAY YEAR YEAR YEAR MONTH DAY I

05000 NUMBER NO.

DOCKET NUMBER FACILITY NAME 05 04 2009 0

06 18 2009 2009 - 002 05000 I

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check a/l that apply)
9. OPERATING MODE o 20.2201 (b) o 20.2203(a)(3)(i) o 50.73(a)(2)(i)(C) o 50.73(a)(2)(vii) o 20.2201 (d) o 20.2203(a)(3)(ii) o 50.73(a)(2)(ii)(A) o 5073(a)(2)(viii)(A) 3 o 20.2203(a)(1) o 20.2203(a)(4) o 50.73(a)(2)(ii)(B) o 50.73(a)(2)(viii)(B) o 20.2203(a)(2)(i) o 50.36(c)(1 )(i)(A) o 50.73(a)(2)(iii) o 50.73(a)(2)(ix)(A) o 20.2203(a)(2)(ii) o 50.36(c)(1)(ii)(A) o 5O,73(a)(2)(iv)(A) o 50.73(a)(2)(x)
10. POWER LEVEL o 20.2203(a)(2)(iii) o 50.36(c)(2) o 50.73(a)(2)(v)(A) o 73.71 (a)(4) o 20.2203(a)(2)(iv) o 50 46(a)(3)(ii) o 50.73(a)(2)(v)(B) o 73 71 (a)(5) 000 o 20.2203(a)(2)(v) o 50.73(a)(2)(i)(A) o 50,73(a)(2)(v)(C) o OTHER o 20.2203(a)(2)(vi)

~ 50 73(a)(2)(i)(8) o 50.73(a)(2)(v)(D)

Specify in Abstract below or in NRC Form 366A

12. LICENSEE CONTACT FOR THIS LER FACILITY NAME ITElEPHONE NUMBER (Include Area COde)

Edwin I. Hatch / Kathy Underwood, Performance Improvement Supervisor 912-537-5931 MANU REPORTABLE MANU REPORTABLE

CAUSE

SYSTEM COMPONENT

CAUSE

SYSTEM COMPONENT FACTURER TO EPIX FACTURER TO EPIX D

SB SHV A585 YES

14. SUPPLEMENTAL REPORT EXPECTED
15. EXPECTED SUBMISSION YEAR DYES (If yes, complete 15. EXPECTED SUBMISSION DATE)

I:8J NO MONTH DAY DATE ABSTRACT (Limit to 1400 spaces, i. e., approximately 15 single-spaced typewritten lines)

On May 4,2009 at 851 EDT, Unit 1 was in hot shutdown, Mode 3. Stroke time testing of the inboard Main Steam Line Isolation Valve (MSIV), 1B21-F022B, failed to meet both the procedural minimum limit, and the Technical Specification minimum limit of greater than or equal to three seconds. The valve closed in 1.53 seconds.

A Work Order was generated to determine the cause of the failure. Upon investigation, it was found there was no oil in the actuator due to a leak at a fitting on the actuator. The oil provides a dampening effect for the valve closure and the absence of oil allowed the valve to close faster than desired. The oil leak originated from a 3/4 inch NPT port on the dashpot cylinder. The cause of the leak is attributed to degradation of the Teflon tape applied as a thread sealant Corrective actions consist of removing, cleaning and reassembling fittings to the port using Loctite 5772 in place of the Teflon tape. In addition, the procedure for actuator dashpot reassembly has been revised to require use of the Loctite 5772 sealant. In addition to improve reliability of all threaded fittings for the MSIV actuators the procedure has been revised to require cleaning and the application of new Loctite 5772 sealant any time threaded connections are removed from the actuator.

NRC FORM 366 (9-2007)

PRINTED ON RECYCLED PAPER (If more space is required, use additional copies of NRC Form 366A)

PLANT AND SYSTEM IDENTIFICATION

General Electric - Boiling Water Reactor Energy Industry Identification System codes appear in the text as (EllS Code XX).

DESCRIPTION OF EVENT

On May 4,2009 at 851 EDT, Unit 1 was in hot shutdown, Mode 3. Stroke time testing of the inboard Main Steam Line Isolation Valve (MSIV) (EllS Code SB), 1B21-F022B, failed to meet both the procedural minimum limit, and the Technical Specification minimum limit of greater than or equal to three seconds. The valve closed in 1.53 seconds. A Work Order was initiated to identify and repair the cause of the failure. Once the failure mechanism was identified it was repaired. In addition inspection of the other MSIV's on both Unit 1 and Unit 2 was performed. This inspection determined that a similar condition does not exist on any of the other MSIV's.

CAUSE OF EVENT

This event was caused by the loss of oil in the actuator due to a leak at a fitting on the actuator. The oil provides a dampening effect for the valve closure and the absence of oil allowed the valve to close faster than desired. The oil leak originated from a 3/4 inch NPT port on the dashpot cylinder. The cause of the leak is attributed to degradation of the Teflon tape applied as a thread sealant.

REPORTABILITY ANALYSIS AND SAFETY ASSESSMENT This event is reportable per 10 CFR 50.73 (a)(2)(i)(B) because a condition prohibited by the Technical Specification existed. Specifically, the 'B' inboard MSIV closed faster than the limit established by the plant's Technical Specifications.

The MSIV's have a specific stoke time listed in the Technical Specification. This acceptable closing time range is intended to perform a duel function. First to close and perform a primary containment (EllS Code NH) isolation function with a maximum closure time which limits the release of radiological products. Second the associated minimum closure time reduces vessel peak pressure and protects against fuel damage. In this event one MSIV closed faster than the minimum time stated in the Technical Specification. An evaluation of the effect of this quicker valve response was performed and is summarized below.

Hatch Core Analysis has performed an evaluation of the MSIV closure event for Hatch-1 Cycle 24 in which one MSIV closes faster than the minimum allowable time required by Technical Specification (TS) SR 3.6.1.3.6. The approach taken in this evaluation was to model one MSIV closing in the as-measured time of 1.53 seconds and the remaining valves closing in the minimum allowable Technical Specification time of 3.0 seconds, and then run applicable reload licensing calculations. PRINTED ON RECYCLED PAPER U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)

(9-2007)

CONTINUATION SHEET

1. FACILITY NAME
2. DOCKET
6. LER NUMBER
3. PAGE SEQUENTIAL

!REVISION YEAR NUMBER NUMBER Edwin I. Hatch Nuclear Plant Unit I 05000321 3

OF 5

2009 002 0

This analysis was performed using GNF's NRC-approved ODYN BWR transient simulation code which models the short-term plant response to pressurization events. ODYN's plant model is based on one average steamline. To account for the two valve closure times, the function of valve area versus time after the closure signal was weighted to reflect one valve closing faster than the remaining valves.

The MSIV fast closure with direct scram on valve position (MSIVD) and the MSIV fast closure with flux scram (MSIVF) events were analyzed. The assumptions listed below are common to both the MSIVD and MSIVF results.

1. 1 MSIV closes in 1.53 seconds and the remaining valves close in 3.0 seconds.
2. The smallest throat diameter (4.905 in) was used for all SRVs.
3. A conservative axial power shape was used for all test cases. This assumption results in a top-peaked power shape at the end of cycle which retards the effect of the reactor scram.
4. The reactor is operating at either 105% of rated core flow, which is the maximum allowable core flow at rated power, or at 92.9% of rated core flow, which is the minimum licensed core flow at rated power.
5. 1 of the 11 SRVs is assumed to be out of service.

The MSIVD event with all MSIVs closing in 3 seconds is classified as a non-limiting Anticipated Operational Occurrence (AOO) in the FSAR, but it was analyzed to verify it did not become a limiting event due to the faster MSIV closure time. The MSIVD results presented in this document are based on the following additional assumptions:

1. The initial reactor dome pressure is at the nominal, rated value of 1045 psig.
2. The MSIV closure event occurs at 100% of rated thermal power.
3. All control rods insert at the COLR Option B scram speeds. Note: These scram speeds have always been met for Plant Hatch.
4. Credit is taken for the direct scram on the MSIV safety-grade valve position switches.

The MSIVF event is used to evaluate compliance with the 1325 psig Reactor Coolant System (EllS Code AD) Pressure Safety Limit (Technical Specification 2.1.2) during the worst anticipated reactor vessel over pressurization event. The Tech Spec Safety Limit is evaluated at the top of the reactor vessel in the steam dome and the value is conservatively selected to ensure the 1375 psig ASME Boiler and Pressure Vessel Code overpressure limit is not violated at the bottom of the reactor vessel. The following additional assumptions are made for the MSIVF event:

1. The direct scram from the valve position switches fails; therefore, the scram is delayed until the APRM system's high neutron flux scram signal is reached.
2. The initial reactor dome pressure is at the maximum value of 1058 psig as specified in Tech Spec SR 3.4.10.1.
3. The MSIV closure event occurs at a reactor power level (100.5%) which is slightly greater than rated power at the very end of cycle when there are no control rods in the PRINTED ON RECYCLED PAPER

NRC FORM 3BBA (9-2007)

LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET U.S. NUCLEAR REGULATORY COMMISSION

1. FACILITY NAME
2. DOCKET
6. lER NUMBER
3. PAGE Edwin I. Hatch Nuclear Plant Unit I 05000321 YEAR I SEQUENTIAL IREVISION NUMBER NUMBER

\\---------"-----

2009 002 o

4 OF 5

instrument uncertainties.

4. COLR Option A scram speeds are used. These are equivalent to the Tech Spec limits for TS 3.1.4.

The results of this analysis are given in Table 1.

The peak dome and vessel pressures remained below their limits of 1325 psig and 1375 psig, respectively, for all cases. The direct scram improves margin to the overpressure limits because the neutron flux and ultimately the thermal power decrease much sooner than in the flux scram case. Also, the scram speed was faster for the MSIVD event since it used the Option B scram speeds.

Specified acceptable fuel design limits (SAFDLs) were checked for the MSIVD event since it is classified as an AOO in the Plant Hatch FSAR. The LiCPR results were not calculated by ODYN for the MSIVD cases because the peak fuel surface heat flux does not rise above its initial value. Therefore, there was no effect on the Operating Limit MCPR values. Also, as a result of no increase in heat flux, the fuel rod thermal and mechanical overpowers were insignificant and well below the allowable limits.

The SAFDLs are not applicable to the MSIVF event because it is classified as a special event that is used to conservatively evaluate compliance with the ASME Boiler & Pressure Vessel over pressurization limit for the reactor pressure vessel.

Based on this analysis, the faster (1.53 sec) closure of one MSIV would have no discernable affect on the response of the fuel or peak pressure relative to the 3 second TS values. In fact, the peak pressures of the MSIVF cases were only marginally higher than the results of the Hatch-1 Cycle 24 reload licensing analysis (Table 2).

Table 1 - MSIV Transient Results Flow Peak Peak Event Conditio Peak Heat OLMCPR OLMCPR Dome Vessel TOP MO Flux B

A Pressure Pressure P

n

% initial ref (psig)

(psig)

MSIVD ICF 100.03 no effect no effect 1205.1 1244.9 0.0 7.6 MSIVD MELLLA 100.02 no effect no effect 1201.0 1236.3 0.2 0.2

~IVF ICF 128.92 N/A N/A 1292.9 1329.3 N/A N/A MSIVF MELLLA 127.13 N/A N/A 1293.0 1326.2 N/A N/A OLMCPR : Operating Limit Minimum Critical Power Ratio (Option AlB Scram Speeds)

TOP

Thermal Overpower MOP
Mechanical Overpower PRINTED ON RECYCLED PAPER U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)

(9-2007)

CONTINUATION SHEET

1. FACILITY NAME
2. DOCKET
6. LER NUMBER
3. PAGE SEQUENTIAL REVISION YEAR I

NUMBER NUMBER Edwin I. Hatch Nuclear Plant Unit I 05000321 5

OF 5

2009 002 o

Table 2 - MSIV Results from H1C24 Reload Licensing Analysis Peak Event Flow Condition Dome Pressure Peak Vessel Pressure (psig)

(psig)

MSIVF ICF 1291 1328 MSIVF MELLLA 1292 1324

CORRECTIVE ACTIONS

The leaking fitting was removed, cleaned and reassembled using Loctite 5772 in place of the Teflon tape. The oil was replaced and functional testing was satisfactorily performed.

Procedures 52SV-B21-001-1 and 52SV-B21-001-2, MSIV Limit Switch Response and Component Inspection/Repair, for actuator dashpot reassembly have been revised to require use of the Loctite 5772 sealant. In addition to improve reliability of all threaded fittings for the MSIV actuators the procedure has been revised to require cleaning and the application of new Loctite 5772 sealant any time threaded connections are removed from the actuator.

ADDITIONAL INFORMATION

Other Systems Affected: None

Failed Components Information

Master Parts List Number: 1B21-F022B EllS System Code: SB Manufacturer: Atwood & Morrill Co.

Reportable to EPIX: Yes Model Number: VPF279221 Root Cause Code: D Type: Valve, Shutoff EllS Component Code: SHV Manufacturer Code: A585 Commitment Information: This report does not create any new permanent licensing

commitments

Previous Similar Events

There are no similar events within the past two years in which an MSIV stroke time tested outside of the time specified in the Technical Specifications. PRINTED ON RECYCLED PAPER

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