ML17229A851

LER 98-005-00:on 980807,discovered That PORV Margins Were Insufficient to Accommodate Addl Conservatism.Caused by Inadequacies in Original Vendor MOV Methodology.Will Implement Planned Valve Actuator mods.W/980902 Ltr

ML17229A851
Person / Time
Site:	Saint Lucie
Issue date:	09/02/1998
From:	Frehafer K, Stall J FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
IEIN-96-048, IEIN-96-48, L-98-223, LER-98-005-01, LER-98-5-1, NUDOCS 9809090173
Download: ML17229A851 (8)

Text

~ CATEGORY 3 REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9809090173 DOC.DATE: 98/09/02 NOTARIZED: NO DOCKET ¹ FACIL:50-389 St. Lucie Plant, Unit 2, Florida Power 6 Light Co. 05000389 AUTH.NAME AUTHOR AFFILIATION FREHAFER;K.W.'lorida Power 6 Light Co.

STALL,J.A. Florida Power 5 Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 98-005-00 on 980807,discovered that PORV margins were

'insufficient to accommodate addi conservatism. Caused by inadequacies in original vendor MOV methodology. Will implement planned valve actuator mods.W/980902 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

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

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-3 PD 1 1 GLEAVES,W 1 1 INTERNAL: ACRS 1 1 AEOD/SPD/RAB 2 2 AEOD/SPD/RRAB 1 1 NTE 1 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/EZB 1 1 RGN2 FILE 01 1 1 D

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 WASTETH NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LZSTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD) ON EXTENSION 415-2083 FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 23 ENCL 23

Florida Power 5 Light Company, 650t South Ocean Drive, Jensen Beach, FL34957 September 2, 1998 FPL L-98-223 10 CFR 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Re: St. Lucie Unit 2 Docket No. 50-389 Reportable Event: 1998-005-0 Date of Event: August 7, 1998 New MOV Methodology Caused Past PORV Block Valve 0 erabilit Problem The attached Licensee Event Report 1998-005 is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.

Very truly yours, J. A. Stall Vice President Ii, St. Lucie'lant JAS/EJW/KWF Attachment cc: Regional Administrator, USNRC Region II Senior Resident Inspector, USNRC, St. Lucie Plant 980'tr0901.73 'it80902 PDR ADOCtt'M00389 S PDR an FPL Group company

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3160-0104 EXPIRES 06/30/2001 Ia-1999)

Estimatod burden por response lo comply with this mandatory information collection roquest: 50 hm. Reported lessons learned aro incorporated tnto the licensing process and fed back to industry. Forward comments regarding LICENSEE EVENT REPORT (LER) burdon estimato to the Records Management Branch (TA F33) US. Nuclear Reguhtory Commission, Washington, DC 205554001, and to the Papenvork Reduction Proiect (31504104$ , Oflice of Management and Budget, (See reverse for required number of Washington DC 20503. If an information colfecgon does not display a currently va(ld OMB control number, the NRC may not conduct or sponsor, digits/characters for each block) and a person is not required to respond to, lho information colloction.

FACILITY NAME (1) DOCKET NUMBER (2) PAGE (3)

St. Lucie Unit 2 05000389 Page 1 of 4 TITLE (4)

New MOV Methodology Caused Past PORV Block Valve Operability Problem EVENT DATE (6) LER NUMBER 6 REPORT DATE 7 OTHER FACIUTIES INVOLVED 8 SEQUENTIAL REVISION FACIUTY NAME DOCKET NUMBER MONTH DAY NUMBER NUMBER DAY P

FACIUTY NAME DocKET NUMsot 08 07 1998 1998 - 005 - 00 09 02 1998 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQ UIREMENTS OF 10 CFR 5: (Check ono or moro) (11)

MODE (9) 20.2201 (b) 20.2203(a) (2) (v) 60.73(a)(2) (i) '60.73(a)(2)(viii)

POWER 20.2203(a) (1) 20.2203(a) (3) (t) 60.73(a)(2)(ii) 60.73(a) (2)(x)

LEVEL (10) 100 20.2203(a)(2) (i) 20,2203(a) (3) (ii) 60.73(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) 60.36(c) (1) 60.73(o)(2)(v) Specify In Abstract below or 20.2203 (o) (2) (iv) S0.36(c)(2) S0.73(a) (2) (vii) In NRC Form 30BA LICENSEE CONTACT FOR THIS LER 12 TELEPHONE NUMSER gnoruda Araa Coda)

Kenneth W, Frehafer, Licensing Engineer (561) 467 - 7748 COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 13 CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE REPORTABLE TO EPIX CAUSE SYSTEM COMPONENT MANUFACIURER TO EPIX B L200 NO SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY EXPECTED YES SUBMISSION (If yes, compioto EXPECTED SUBMISSION DATE). X No DATE (16)

ABSTRACT iLimitto 1400 spaces, i.e., approximately 16 single-spaced typewritten linesl (16)

On August 7, 1998, St. Lucie Unit 2 was in Mode 1 at 100 percent power. During a review of NRC Information Notice 96-48, Supplement 1, Engineering discovered that the Unit 2 power operated relief valve block valve (V-1476 and V-1477) margins were insufficient to accommodate the additional conservatism specified in NRC Information Notice 96-48, Supplement 1, and assure valve closure. Operations entered the one-hour ACTION statement for Technical Specification 3.4.4.a at 19159 hours on August 7, 1998.

The ACTION statement was exited at 20:07 hours the same day when both Unit 2 power operated relief valve block valves were closed with power removed in accordance with Technical Specification requirements.

The cause of this event was inadequacies in the original vendor motor operated valve methodology as documented in Limitorque Technical Update 98-01 and NRC Information Notice 96-48 Supplement 1. The new methodology required an additional conservatisms when'evaluating a Limitorque AC powered motor operator's performance.

Corrective actions include the immediate actions taken on August 7, .1998, and the implementation of the planned valve actuator modifications during the upcoming fall Unit 2 Cycle 11 1998 refueling outage.

NRC FOAM 399 IB 1999)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (8-1998]

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACIUTY NAME (1) DocKET LER NUMBER I6) PAGE (3)

NUMBER 2 SEQUENTIAL REVISION NUMBER NUMBER St. Lucie Unit 2 05000389 Page 2 of 4 1998 005 00 TEXT /Ifmore speceis required, use addidonel copies of NRC Form 366A/ I17)

Description of Event On August 7, 1998, St. Lucie Unit 2 was in Mode 1 at 100 percent power. During review of NRC Information Notice (IN) 96-48, Supplement 1, Engineering discovered that the Unit 2 power operated relief valve (PORV) block valve (V-1476 and V-1477) margins were insufficient to assure valve closure. In light of recent tests and studies of motor actuator output, Limitorque retracted its relaxation of the sizing criteria for AC powered motor actuators through issuance of Limitorque Technical Update (TU) 98-01. The Limitorque TU revised requirements such'that an additional factor of conservatism needs to be added to evaluate the motor operator's performance. NRC IN 96-48, Supplement 1, titled "Motor Operated Valve Perfonnance Issues," disseminated this information to the industry.

Operations entered the one-hour ACTION statement for Technical Specification 3.4.4.a at 19:59 hours on August 7, 1998. The ACTION statement was exited at 20:07 hours the same day when both Unit 2 PORV block valves were closed with power removed in accordance with Technical Specification requirements.

Cause of the Event The cause of this event was 'inadequacies in the original vendor motor operated valve (MOV) methodology as documented in Limitorque TU 98-01 and NRC IN 96-48, Supplement 1.

Analysis of the Event Technical Specification 3.4.4. requires that each 'PORV block valve be operable in Modes 1, 2, and 3, with no more than one block valve open. ACTION a. states that:

"With one or more block valve(s) inoperable, within? hour either restore the block valve(s) to OPEKLBLE status or close the block valve(s) and remove power from the block valve(s); otherwise, be in at least HOT SMDBY 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 />. "

The past inoperability of the PORV block valves constitutes a condition for which firm evidence exists that the condition existed in the past. It is concluded that the past inoperability time exceeded the allowed outage time (i.e., greater than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />) of Technical Specification 3.4.4.a and therefore constitutes operation prohibited by the plant's Technical Specifications. Accordingly this condition 'is reportable under 10 CFR 50.73(a)(2) (i)(B), that states "Licensees shall report: 'any operation or condition prohibited by the plant's Technical Specifications.'"

The purpose of the Limitorque Technical Update (TU) was to provide new guidance to determine the output torque capability of a Limitorque valve actuator with an AC motor. The motor operated valve (MOV) output torque capability is determined by using the following factors:

1. Motor Rated Torque

2. Pullout Efficiency NRC FORM 3BBA IB-19981

0 P

I

• 'v "0 l

RC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I8-1998)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FAGILITYNAME I1) DOCKET LER NUMBER (6) PAGE I3)

NUMBER I2)

SEQUENTIAL REVISION NUMBER NUMBER St. Lucie Unit 2 05000389 Page 3 of 4 1998 - 005 00 TEXT (Ifmore space is required, use additional copies of NRC Form 3MAI I17)

3. Overall Actuator Gear Ratio

4. Motor Texminal Voltage

5. Motor Rated Voltage

6. Application Factor (AF) selected in accordance with Limitorque SEL-4 Engineering reviewed the current NRC Generic Letter (GL) 89-10 MOV program calculations and determined that the Motor Rated Torque, Overall Actuator Gear Ratio, and the Motor Terminal and Rated Voltage factors were consistent with the TU requirements.

However, for some MOVs, calculations utilized motor running efficiency (versus pullout efficiency) and the relaxed AF criteria previously provided by Limitorque in TU 93-03. TU 93-03 allowed the assumption of an AP of 1.0 (rather than 0.9) when the motor voltage was less than 90 percent of the motor's rated voltage. Engineering reviewed applicable MOVs, and determined that several valves did not have sufficient margin to account for the additional conservatism introduced by Limitorque TU 98-01.

However, only the Unit 2 PORV block valves, V-1476 and V-1477, were determined to be a Technical Specification OPERAEILITY concern. Using the new methodology for the Unit 2 PORV block valves, the calculated closing thrust was 10,464 lbs., and the required closing thrust is 17,440 lbs. Therefore, there is a possibility that the PORV block valves would not close if required.

Analysis of the Effect on Safety The past inoperability of the PORV block valves did not constitute operation outside the design basis of the plant and would not have prevented the fulfillment of a safety function. The Technical Specifications require that one block valve be. closed during power operation. In the event of an inadvertent PORV opening, the safety analysis does not credit closing of the associated block valve to prevent exceeding safety -limits.

The PORVs are discussed in Emergency Operating Procedure EOP-15 for initiation of once through cooling. However, this is a beyond design basis scenario that requires multiple safety related system failures.

The past inoperability of the PORV block valves would not have adversely affected the operation of the PORVs for low temperature over pressure protection (LTOP) . In the LTOP mode the PORV block valves only need to be open and are not required to be operated.

The PORV system is a high/low pressure interface with the primaxy system. To preclude a fire-induced LOCA, the safe shutdown analysis protects the PORVs from possible spurious operation. The PORVs'ontrol and power cables are protected or manual action is taken to isolate the PORVs'ower by use of isolate switches in the electrical penetration room in case of a fire in the control room or cable spread

- room. No credit is taken for operation of the Unit 2 PORV block valves as far as the 10 CFR 50, Appendix R safe shutdown analysis is concerned.

NRC FOAM SBBA IB.19981

s RC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (0-1880)

LICENSEE EVENT REPORT (LER)

TEXT. CONTINUATION FACILITYNAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

SEQUENTIAL REVISION NUMBER NUMBER St. Lucie Unit 2 05000389 Page 4 of 4 1998 - 005 - 00 TEXT ilfmoro speceis required, use edditionel copies of NRC Form 366A) (17)

Analysis of the Effect on Safety (cont'd)

Based on the preceding discussion, past PORV block valve inoperability had no adverse affect on the health and safety of the public.

However, in order to provide operational flexibility to the operators during postulated beyond design bases events, St. Lucie implemented temporary system alterations (TSAs) on the Unit 2 PORV block valves to restore these valves to operable status. The TSA for V-1476 was implemented on August 14, 1998, and the TSA for, V-1477 was implemented on August 19, 1998. The TSAs will be removed after the permanent plant modifications are implemented next outage.

Corrective Action

1. Immediate action was taken on August 8, 1998 to close the PORV block valves and remove power in accordance with the requirements of Technical Specification 3.4.4.a.

2. St. Lucie implemented temporary system alterations (TSAs) on the Unit 2 PORV block valves to restore these valves to operable status on August 14, 1998, for V-1476, and August 19, 1998, for V-1477.

3. Both PORV block valves will be modified during the upcoming fall 1998 Unit 2 Cycle 11 refueling outage under PC/M 98013.

4. The St. Lucie GL 89-10 program requires review of industry operating experience and the incorporation of new information into the program documentation. The information and issues identified in NRC ZN 98-48 Supplement 1 will be incorporated into the GL 89-'10 program documentation by January 31, 1999.

Similar Events LER 50-335/97-009, dated September 17, 1997, reported MOV calculation deficiencies associated with the St. Lucie Unit 1 PORV block valve V-1403.

Failed Components Identified Component: V-1476 and V-1477, PORV block Valve Motor/Actuator Manufacturer: Limitorque Model Number: SB-00 (3G0861A)

NRC FORM 300A (0.18881

)4