ML17354B192

LER 98-007-00:on 981020,containment Purge Supply,Valve Opened Wider than TS Limit.Caused by Improper Setting of Mechanical Stops.Incorporated Improved Standard Method of Measuring Angular Valve Position Into Sp.With 981118 Ltr

ML17354B192
Person / Time
Site:	Turkey Point
Issue date:	11/18/1998
From:	Hovey R, Shukla G FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-98-282, LER-98-007-02, LER-98-7-2, NUDOCS 9811250075
Download: ML17354B192 (13)

Text

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CATEGORY 1 REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9811250075 DOC.DATE: 98/11/18 NOTARIZED: NO FACIL:50-250 Turkey Point Plant, Unit 3, Florida Po~er and Light DOCKET ¹

, C 05000250 AUTF...NAME AUTHOR AFFILIATION SHUKLA,G.S. Florida Power 6 Light Co.

HOVEYiR.J. Florida Power 6 Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 98-007-00:on 981020,containment purge supply, valve opened wider than TS limit.Caused by improper setting of mechanical stops. Incorporated improved standard method of measuring angular valve position into SP.With 981118 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-3 PD 1 1 JABBOUR,K 1 1 INTERNAL: A - B 2 2 AEOD/SPD/RRAB 1 1 ILE CENTER 1 NRR/DE/ECGB 1 1 1 1 NRR/DE/EMEB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOHB 1 1 NRR/DRCH/HQMB 1 1 NRR/DRPM/PECB 1 1 NRR/DSSA/SPLB 1 1 RES/DET/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 1 1 NOAC POORE,W. 1 1 NOAC QUEENER,DS 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL i'RIDSn RECIPIENTS.

PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRZBUTION L'ZSTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROZ DESK (DCD) ON EXTENSION 415-2083 FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 22 ENCL 22

NOil j. 8 1998 L-98-282 10 CFR 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Re: Turkey Point Unit 3 Docket No. 50-250 Reportable Event: 1998-007-00 Date of Event: October 20, 1998 Containment Pur e Su I Valve 0 ened Wider Than Technical S ecifications Limit.

The attached Licensee Event Report is being submitted pursuant to the requirements of 10 CFR 50.73.

Very truly yours, R. J. Hovey Vice President Turkey Point Plant GSS Attachment cc: Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, Turkey Point Nuclear Plant eSX<250075 eSiCaa PDR ADQCK 05000250 S PDR an FPL Group company

t APPROVED 8Y OMB NO. 3150%104 EXPIRES 06/30/2001 NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (6-1ggs) Estimated burden per response to comply with this mandatory information collection request: 50 hrs. Reported lessons learned are incorporated into tho licensing process end fed back to industry. Forward comments regarding LICENSEE EVENT REPORT (LER) burden estimate to the Records Management Branch (T4 F33). U.S. Nudear Regulatory Commission. Washington. DC 205554)001 and to the Papenvork

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Reduction Project (3150%104), Ofree of Management and Budget, (See reverse for requited number of Washington, DC 20503. Ifen information colkcson does not display a currently digits/characters for each block) valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, tho information collection.

FACILITYNAME (1) DOCKET NUMBER (21 PAGE (31 TURKEY POINT UNIT 3 05000250 1 OF 5 TITLE (4)

Containment Purge Supply Valve opened wider than the Technical S ecifications Limit EVENT DATE 5 LER NUMBER 6 REPORT DATE 7 OTHER FACILITIES INVOLVED(6)

FACILITYNAME DOCKET NUMBER REVISIO SEQUENTIAL N MONTH DAY YEAR NUMBER NUMBER MONTH DAY FACILITYNAME DOCKET NUMBER 10 20 1998 1998 - 007 - 00 11 18 1998 THIS REPORT IS SUBMITTED PURSUANT TO THE REQU IREMENTS OF 10 CFR: Check one or more 11 OPERATING MODE 9 20.2201 b 20.2203a 2 v 50.73 a 2 I 50.73 a 2 viii 20.2203 a 1 20.2203 a 3 i 50.73 a 2 ii 50.73 a 2 x POWER LEVEL 10 00 20.2203a 2 i 20.2203 a 3 ii 50.73 a 2 iii 73.71 20.2203 a 2 ii 20.2203 a 4 50.73 a 2 iv OTHER 20.2203 a 2 Iii 50.36 c 1 50.73 a 2 v Specify in Abstract below or 20.2203 a 2 rv 50.36 c 2 50.73a 2 vii in NRC Form 366A LICENSEE CONTACT FOR THIS LER 12 TELEPHONE NUMBER (Indude Area Code)

GIRIJA S. SHUKLA LICENSING ENGINEER 305-246-6047 COMPLETE ONE LINE FOR EAC COMPONENT FAIL R DESCRIBED IN THIS REPORT (13)

REPORTABLE REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER TO EPIX CAUSE SYSTEM COMPONENT MANUFACTURER TO EPIX SUPPLEMENTAL REPORT EXPECTED 14 EXPECTED YES SUBMISSION If s corn lete EXPECTED SUBMISSION DATE . X No DATE 15 ABSTRACT (Limit to 1400 spaces, I.e. approxlmately15 single-spaced typewritten lines) (16)

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During the Unit 3 Cycle 17 refueling outage, while performing a surveillance per Technical Specification (TS) 4.6.1.7.3, the mechanical stops for the Containment Purge Supply Isolation Valve, POV-3-2601, were found to be set to allow a valve opening of 38 degrees which is wider than 33 degrees allowed by TS 3.6.1.7.b. This valve is presumed to have had the same opening of 38 degrees when it was opened, prior to shutdown for the refueling outage, for more than 55 hours6.365741e-4 days <br />0.0153 hours <br />9.093915e-5 weeks <br />2.09275e-5 months <br /> for containment purge before reaching COLD SHUTDOWN conditions. Therefore, the valve did not comply with the requirements of TS.

The cause of this event was improper setting of the mechanical stops, which was discovered when a new and improved measuring technique was used for the first time to measure the angular position of valve POV-3-2601.

Corrective actions include incorporating an improved standard method of measuring angular valve position in the existing surveillance procedures, providing margin between the TS limit and the procedural limit by establishing the nominal set value for the mechanical stops sufficiently below the present 33 degrees setting, and adjusting purge valves to the new open stop setpoint.

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME DOCKET NUMBER. LER NUMBER PAGE NO.

TURKEY 'POINT UNIT 3 05000250 1998-007-00 2 OF 5 I. DESCRIPTION OF THE EVENT On October 20, 1998, at 1000 EDT, during Florida Power and Light's Turkey Point Nuclear Plant Unit 3 Cycle 17 refueling outage, while performing a surveillance per Technical Specification (TS) 4.6.1.7.3, the mechanical stops for the Containment Purge Supply Isolation Valve POV-3-2601 [VA:isv] were found to be set to allow a valve opening of 38 degrees which is wider than 33 degrees allowed by TS 3.6.1.7.b. This valve is presumed to have had the same opening of 38 degrees when it was opened prior to shutdown for the refueling outage for more than 55 hours6.365741e-4 days <br />0.0153 hours <br />9.093915e-5 weeks <br />2.09275e-5 months <br /> between September 19, 1998, and September 21, 1998 for containment purge before reaching COLD SHUTDOWN conditions.

Therefore, the valve did not comply with the requirements of TS 3.6.4.d.

This event is reportable pursuant to 10 CFR 50.73(a)(2)(i) (B) .

During the performance of the surveillance procedure 3-PMI-051.7, "Containment Ventilation Isolation Valve Position Indication Channel Calibration," the open limit mechanical stops for the Containment Purge Supply Isolation Valve POV 2601 were found to be out of specification. The valve POV-3-2601 stroked open to 38 degrees while the specified acceptance criteria is less than or equal to 33 degrees. Following this discovery, the travel limits for the opening of the valve were reset to within the 33 degrees acceptance criteria of the surveillance procedure.

Valve POV-3-2601 is the inside containment 48 inch containment purge supply isolation valve for the containment purge system. The Containment Purge System is designed to purge the containment atmosphere for unlimited access during shutdown periods. The Containment Purge System is independent of the Auxiliary Building Ventilation System [VF] and includes provisions for handling both supply and exhaust air. The containment purge supply and exhaust butterfly valves, both inside and outside the containment, are normally closed during power operation. When the plant is in a state other than cold shutdown or refueling, the purge supply valves are limited to opening angles of 33 degrees. The open limit,mechanical stop settings are verified by surveillance at each refueling outage.

The Limiting Condition for Operation (LCO) contained in TS 3.6.1.7.b, applicable in Modes 1, 2, 3, and 4, states that "the purge supply and exhaust isolation valves shall not be opened wider than 33 or 30 degrees, respectively (90 degrees is fully open)." However, between September 19, 1998, and September 21, 1998, the Unit 3 containment purge system was operated for 55.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> in Modes 1 through 4 for containment purge before and at the beginning the Unit 3 Cycle 17 refueling outage. During that time the valve POV-3-2601 is presumed to have been open to the as-found position of 38 degrees. Since it was opened wider than allowed by technical specifications, the valve POV-3-2601 is considered to have been inoperable.

Technical Specification 3.6.4 "Containment Isolation Valves" applies to inoperable containment isolation valves. The specification applicable in Modes 1 through 4, states that "Each containment isolation valve shall be OPERABLE with isolation times less than or equal to required isolation times."

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY 'POINT UNIT 3 05000250 1998-007-00 3 OF 5 The action statement requires, "With one or more isolation valves inoperable, maintain at least one isolation valve OPERABLE in each affected penetration that is open and either: a. Restore the inoperable valve(s) to OPERABLE status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, or d. Be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />."

Unit 3 containment purge was in operation in Modes 1 through 4 for 55.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />. This value represents the total time containment purge was in operation during the Technical Specification applicable operating Modes 1 through 4. Based on initial opening of the purge valve in Mode 1 and entering Mode 5 over 55 hours6.365741e-4 days <br />0.0153 hours <br />9.093915e-5 weeks <br />2.09275e-5 months <br /> later, the requirements of the action statement stated in TS 3.6.4 were not met for an inoperable containment isolation valve POV 2603. Therefore, this condition is reportable pursuant to 10 CFR 50.73.

II. CAUSE OF THE EVENT The cause of this event was improper setting of the mechanical stops which was discovered when a new and improved measuring technique was used for the first time to measure the angular position of the valve POV-3-2601.

The measurement was previously performed per the old technique with'a small protractor and template. The limiting angular position of 33 degrees was transferred from the template to the actuator limit switch plate, which introduced some potential inaccuracy. Furthermore, inaccuracy and readability error may have been incurred due .to the relatively small angle to be measured and the small switch plate (approximately 4 inches) . The new and improved measuring method used recently in performing the surveillance during the Unit 3 Cycle 17 refueling outage employed a fabricated protractor template designed specifically to fit the limit switch plate. This method is considered to be a substantial improvement in accuracy and readability, and contributed to the discovery of higher than the as-left measurement of the angular position of the valve POV-3-2601.

III. SAFETY CONSEQUENCES OF THE EVENT There were no adverse safety consequences as a result of this event.

The safety considerations associated with past operation with the valve stop mispositioned are: (a) dynamic torque applied to the valve while closing during a Design Basis Accident (DBA), and (b) stroke time (closed) with respect to containment isolation. As discussed below, the valve stop mispositioning had no adverse impact on safety.

(a) Dynamic Torque With respect to the 48-inch, valve POV-3-2601, the as-found valve position was 38 degrees open, which exceeds the Technical Specification requirement of limiting the open position to a maximum of 33 degrees (0'osition is fully closed, 90'osition is fully open). The purpose of this limit is to ensure that the valve can achieve and maintain a closed position within 5 seconds

II LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY 'POINT UNIT 3 05000250 1998-007-00 4 OF 5 upon receiving a containment isolation signal. This function must be satisfied without exceeding the actuator's rated breakaway torque as the valve is forced closed by postulated DBA containment pressure.

The 48-inch purge valve actuator is rated as having 87,000 in-lbs. running (dynamic), and 125,000 in-lbs. breakaway (static) torque. The dynamic torque results from the high velocity steam/air mixture exiting containment via valve POV-3-2601 and tends to close the valve. For the disc starting at 35 degrees open, the dynamic torque was calculated to be 51,642 in-lbs. by the vendor.

Utilizing existing vendor analyses for torque determination, the calculated maximum torque for the valve disc starting at 38 degrees open would be 62,000 in-lbs. This torque value is less than the valve actuator's running (dynamic) torque of 87,000 in-lbs., and the breakaway (static) torque of 125,000 in-lbs.

The resulting torque appli.ed to the actuator starting with the valve open 38 degrees is well within the actuator rating, and therefore, is acceptable.

(b) Stroke Time The time required for the valve to stroke closed is an addi.tional operating parameter/performance requirement for POV-3-2601 that must be considered.

Technical Specification 3/4.6.4 states that "Each containment isolation valve shall be operable with isolation times less than or equal to required isolation times" .

The required stroke time (closed) is less than or equal to 5 seconds (closed) .

Based on historical data, the Inservice Test (IST) maximum allowable stroke (closure) time is 2.00 seconds. Valve POV-3-2601 was stroke tested with an acceptable result (0.90 seconds to stroke closed) from the 38 degree open position. This stroke time is consistent with historical IST trending data.

Therefore, the minimal effect .of increased travel on stroke time is considered .

acceptable and does not create an operational concern.

Conclusion Based on the above evaluation, the Containment Purge supply valve POV-3-2601 would satisfy the 5 second closure time requirement based on an as-found 38 degrees valve stop position. In addition, the actuator would remain functional as the resulting dynamic torque on the actuator would not exceed the manufacturer's design ratings. Hence, it is concluded that the valve capability to perform post-accident isolation is not compromised, and loads POV-3-2601 is capable of sustaining the expected LOCA dynamic torque without damage and performing its intended function under design conditions from an initial disc open'angle of 38 degrees or less. Therefore, valve POV-3-2601 is considered 'to have .remained functional with the open stop position set at 38 degrees.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY'POINT UNIT 3 05000250 1998-007-00 5 OF 5 IV. CORRECTIVE ACTIONS

1) An improved standard method of measuring angular valve position will be incorporated in the existing surveillance procedures.

2) A margin will be provided between the TS limit and the procedural limit.

Procedural valve position limits will be revised to include the margin.

The open stop setpoint will be modified to reflect the revised procedural valve position limits. A nominal set value will be established for the mechanical stops below the present 33 degrees setting. This will provide reasonable tolerance in performing the measurement and setting of the angular open position of the valve.

3) All containment purge valves will be adjusted to the new open stop setpoint during the next Unit 3 and Unit 4 refueling outages.

V. ADDITIONAL INFORMATION EIIS Codes are shown in the format [EIIS SYSTEM: IEEE component function identifier, second, component identifier (if appropriate)] .

SIMILAR EVENTS There have been no previous events at Turkey Point Nuclear Units 3 & 4, related to non-compliance of Technical Specifications ACTION statement for inoperable containment purge supply and exhaust isolation valves due to their opening wider than the TS limits.

MANUFACTURING DATA None