05000461/LER-1990-001, :on 900212,drywell Purge Sys Containment Penetration Failed Local Leak Rate Test.Caused by Failure to Remove Cosmolene from Surface of Valve Prior to Initial Installation.Valves Replaced
ML20012C583 | |
Person / Time | |
---|---|
Site: | Clinton ![]() |
Issue date: | 03/13/1990 |
From: | Morgenstern R, Spangenberg F ILLINOIS POWER CO. |
To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
References | |
LER-90-001, LER-90-1, U-601619, NUDOCS 9003220234 | |
Download: ML20012C583 (7) | |
Event date: | |
---|---|
Report date: | |
Reporting criterion: | 10 CFR 50.73(a)(2)(i) |
4611990001R00 - NRC Website | |
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10CFR50.73 Docket No. 50 461 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C.
20555
Subject:
Clinton Power Station - Unit 1 Licensee Event red 2Jt No. 90 001-00
Dear Sir:
Please find ~ enclosed Licensee, Event Report No. 90-001-00:
Failure to Remove Preservative from Valve Results in Accumulation of
' Dirt on Sealina Surface. Failure to Meet Primary Containment Interrity l
~ and Plant Shutdown This report is being submitted in accordance with the requirements of 10CFR50.73.
Sincerely yours,
'F.A.Shanger erg, II (
Manager. Lic. sing add Safety RSF/krm Enclosure ec:
NRC Resident Office NRC Region III, Regional Administrator INPO Records Center Illinois Department of Nuclear Safety NRC Clinton Licensing Project Manager 9003220234 900313 PDR ADOCK 05000461 S
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On February 12, 1990, with the plant in POWER OPERATION, Drywell Purge System containment penetration 1MC-102 failed its Local Leak Rate Test (LLRT).
Performance of the LLRT is required by Technical Specification (TS) 4.6.1.8.3 to demonstrate that Drywell Purge containment isolation l
valves IVQOO4A and IVQ004B are operable. The leakage rate determined by the LLRT also resulted in exceeding the total secondary containment bypass leakage limits of TS 3.6.1.2.d.
The requirements of TS 3.6.1.1 t
for Primary Containment Integrity (PCI) were also not met.
The Shift Supervisor entered the action statement of TS 3.6.1.1 which requires j
restoration of PCI within one hour or shutdown of the plant, j
Troubleshooting to determine which valve was causing the leakage was I
unsuccessful and an orderly plant shutdown was then performed.
The cause I
of this event was the failure to remove Cosmolene from the surface of l
IVQ004B prior to initial installation. The Cosmolene caused dirt to accumulate on the sealing surface of the valve and a requirement to stroke the valves quarterly allowed foreign materials to enter the valve j
sealing surface.
Corrective actions for this event include:
replacing l
valves IVQ004A and IVQ004B; identifying and investigating similar valves; and tagging the valves shut to eliminate the stroking requirement.
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DESCRIPTION OF EVENT
On February 12, 1990,. the plant was in Mode 1 (POWER OPERATION) at approximately 100 percent reactor [RCT) power. The valves [V) of Drywell Purge System [VA) containment penetration [ PEN) IMC 102 were aligned to perform the Local Leak Rate Test (LLRT) of the penetration in accordance with surveillance procedure 9861.02, " Local Leak Rate Testing Requirements". The LIRT of 1MC-102 is performed quarterly to demonstrate that thirty-six inch diameter outboard and inboard Drywell Purge containment isolation valves [ISV) IVQOO4A and IVQOO4B (respectively) are operable as specified in Technical Specification 4.6.1.8.3.
The boundary for this LLRT includes valves IVQ004A, IVQ004B, and outboard and inboard containment isolation bypass valves IVQ006A and IVQ006B (respectively).
At 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br />, with the LLRT in progress and the pressure at 8.3 pounds per square inch gauge (psig), test eng!neers determined that the leakage rate of 1MC-102 was 18,500 standard cubic centimeters per minute (secm).
In response to this determination, test engineers leak checked the packing of each valve within the test boundary and visually checked valve IVQOO6B for seat leakage (1VQ006B was the only valve accessible for this type of check). These checks did not identify any leakage.
The test l
pressure was then increased to 9.6 psig (required test pressure is 9.0 psig minimum) resulting in a leakage rate through 1MC-102 of 19,000 scem.
i The maximum acceptable primary containment leakage allowed by Technical Specification 4.6.1.8.3 through valves IVQ004A and IVQ004B is 3705 seem
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per valve. Therefore, the requirements of Technical Specification l
3.6.1.8 were not met.
Technical Specification 3.6.1.8 requires that IVQOO4A and IVQ004B be operable in Modes 1, 2 (STARTUP) and 3 (110T SilUTDOWN).
At 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br />, test engineers notified the Assistant Shift Supervisor (A/SS) that the leakage rate for penetration 1MC-102 including valves IVQOO4A, IVQ004B, IVQOO6A and IVQ006B was greater than that allowed by Technical Specification 3.6.1.8.
The A/SS was also notified that this leakage rate increased the calculated total secondary containment bypass leakage rate to 38,567 scem.
In accordance with Technical Specification 3.6.1.2.d, the maximum total secondary containment bypass leakage is L
limited to 29,642 seem and therefore the requirements of this specification were also not met.
Since the definition of primary containment integrity requires, in part, that the leakage limits of Technical Specification 3.6.1.2 be met, the Shift Supervisor determined that the requirements of primary containment integrity were not met as required by Technical Specification 3.6.1.1.
For this reason, he entered the action statement of this specification.
This action statement requires that primary containment integrity be restored within one hour or that the plant be in at least 110T SilUTDOWN
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Between 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br /> and 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> on February 12, 1990, test engineers performed troubleshooting in an attempt to quantitatively determine which valve was causing the leakage. However, because of the plant r
configuration, they were unable to make that determination.
At 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br />, in preparation for an orderly plant shutdown, operators began reducing reactor power at a rate of approximately 200 megawatts per hour using reactor recirculation [AD) flow.
At 2220 hours0.0257 days <br />0.617 hours <br />0.00367 weeks <br />8.4471e-4 months <br />, with the plant at sixty five percent reactor power, operators began inserting control rods to continue the reduction of reactor power.
At 0524 hours0.00606 days <br />0.146 hours <br />8.664021e-4 weeks <br />1.99382e-4 months <br /> on February 13, 1990, with the plant at fifteen percent reactor power, operators initiated a manual reactor scram and placed the plant in Mode 3.
At approximately 0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br />, reactor pressure had decreased to less than 700 psig. This created a flow path for the Condensate Booster [SD) pumps j
to feed into the reactor vessel through Reactor Feed Pump Discharge Bypass Throttle Valve 1FW003A which was tagged out.
However, the pressure of the feed pump had previously forced the valve to the open position. This caused an increase in reactor water level to Level 8 (High Water Level). At that point, operators tripped the condensate booster pumps to stop the reactor water level increase. Water level increased to within approximately six inches of the Main Steam Lines. At that point, the manual isolation valve'in the reactor feed pump bypass flow path was closed and level began decreasing. Reactor water level then returned to normal. Bypass throttle valve 1FW003A was subsequently repaired in accordance with Maintenance Work Request D13973 and is awaiting post maintenance testing (PMT).
This PMT is scheduled to be completed prior to the end of the planned maintenance outage (PO 3) currently in progress.
PO 3 is scheduled to be completed by March 27, 1990.
At 2134 hours0.0247 days <br />0.593 hours <br />0.00353 weeks <br />8.11987e-4 months <br /> on February 13, 1990, the plant entered Mode 4 (COLD SHUTDOWN).
No other automatic or manually initiated safety system responses were necessary to place the plant in a safe and stable condition.
No other equipment or components were inoperable at the start of this event such that their inoperable condition contributed to this event, l
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CAUSE OF EVENT
e Investigation determined that penetration 1MC-102 apparently failed its
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LLRT because of seat leakage on valve IVQ004B. This seat leakage was caused by a large amount of dirt or atmospheric dust trapped between the seal [ SEAL] and the valve disk sealing surface. The entire surface of the valve had a large amount of dirt build up because Cosmolene, a sticky preservative,'had not been removed prior to initial installation of the valve. Stroking the valve on a quarterly basis in accordance with Technical Specifications allowed the surface dirt to accumulate on the sealing surfaces of the valve resulting in the seat leakage. No accumulation of dirt was noted in the system piping or on IVQ004A.
l Therefore, the root cause of the LLRT failure and subsequent s;hutdown of the reactor is attributed to the failure to remove the preservative from valve IVQOO4B prior to its initial installation during construction.
CORRECTIVE ACTION
Valves IVQ004A and IVQ004B were replaced in accordance with Maintenance Work Request (MWR) D12948. The replacement valves were verified to have no foreign substances on their surfaces. An LLRT will be performed on penetration IMC 102 prior to the end of PO 3.
A search to identify other valves similar to IVQ004A and IVQ004B which are subject to local leak rate testing, identified only two other valves of the same type, 36 inch diameter Posi Scal butterfly valves.
These valves, IVR001A and IVR001B, Containment Building ventilation supply outboard and inboard containment isolation valves, are located at containment penetration 1MC 101 and have the same quarterly stroke-time test, LLRT, and Technical Specification requirements as IVQ004A and IVQ004B.
A review of maintenance and testing history for valves IVQ004A, IVQ004B, IVR001A, and IVR001B was performed.
The review did not identify any LLRT failures since initial plant operation due to seat leakage, however, valves IVR001B and IVQ004A failed their initial LLRT prior to plant startup. These valves were cleaned and reworked prior to initial plant operation.
Since IVR001B was cleaned and reworked after initial installation and IVQ004A and IVQOO4B have been replaced, valve IVR001A is the only valve of the four that may still be coated with a preservative.
For this reason, MVR D15012 has been initiated to remove, inspect, and I
clean valve IVR001A prior to the end of PO 3.
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j Clinton Power Station has procedures in place to ensure system l
cleanliness is maintained during maintenance and modifications, l
evolutions performed during system operation, and system lay up.
These procedures were not applicable during the construction period when the valves were installed, however, they should prevent the occurrence of a similar event in the future.
Valves IVQ004A, IVQ004B, IVR001A and IVR001B have never been used during
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plant operation in Modes 1 and 2 and are seldom used during plant i
operation in Mode 3.
These valves are stroke time tested on a quarterly basis only to meet Inservice Inspection (ISI) testing requirements.
1 Therefore, to further reduce the possibility of an LLRT failure during j
power operations, these valves may, at the discretion of the Shift j
Supervisor, be tagged shut and declared out-of-service when the plant is operatinr,in Modes 1, 2 and 3.
With the valves out of-service, the ISI stroke-time test requirement can be waived in accordance with American Society of Mechanical Engineers (ASME) Code Section XI, Article IWV-3416.
This will reduce the possibility of future LLRT failures by reducing the possibility of dirt accumulating on the sealing surfaces of the valvss.
An LLRT will be performed on containment penetrations IMC-101 and 1MC-102 l
and the valves of these penetrations will be tagged shut, prior to the end of PO-3.
Additionally, IP will continue to perform quarterly LLRTs
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on these penetrations in accordance with Technical Specification surveillance requirements, l'
ANALYSIS OF EVENT
i This event is reportable under the provisions of 10CFR50.73(a)(2)(i) because of the completion of a nuclear plant shutdown required by Technical Specification 3.6.1.1.
Illinois Power (IP) is performing an assessment to assure that this event did not affect Clinton Power Station's capability to limit the release of fission products to the station site environs following an accident so l
that offsite doses would not have exceeded the values specified in Title 10, Code of Federal Regulations, Part 100, thus ensuring that this event was not safety significant.
If the assessment determines that 10CFR100 limits could have been exceeded, IP will provide a supplemental report including that information.
Penetration 1MC 102 was considered inoperable at 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br /> on February 12, 1990, and is scheduled to be restored prior to startup from PO 3.
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ADDITIONAL INFORMATION
Valve IVQ004B is a thirty six inch diameter butterfly valve, model number 1144 manufactured by POSI-SEAL.
CPS has not previously reported any LLRT failures caused by failure to remove preservatives from a valve. However, LERs 87-062-00,88-008 00, and 89 001 00 reported failures of Main Steam Isolation Valves to meet LLRT requirements because of component wear based on the service the valves had seen.
For further information regarding this event, contact R. W. Morgenstern, Director Plant Technical at (217) 935 8881, extension 3210.
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