ML20036B978
| ML20036B978 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 05/27/1993 |
| From: | Tuckman M DUKE POWER CO. |
| To: | NRC OFFICE OF ENFORCEMENT (OE), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| EA-93-054, EA-93-54, GL-89-10, NUDOCS 9306080009 | |
| Download: ML20036B978 (9) | |
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Duke Ibuer Ccmpurry AfS TuciusN.
- Cawwba N:xlear Generatant; Department Vice President 4800 Concord Road
'(803)Kil-32t5 0ifice hak, SC 23745 (803)831-3426 Tax t
DUKE POWER May 27,1993 Director, Office of Enforcement U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555
Subject:
Catawba Nuclear Station Docket Nos. 50-413 and 50-414 Reply To Notice Of Violatim Enforcement Action 93-054 Please find attached Duke Power's response to the Level lil violatien cited in the Notice of Violation and Proposed imposition of Civil Penalty dated April 30,1993.
Enclosed is Duke Power's check in the amount of Seventy-Five Thousand Dollars
($75,000). This amount constitutes payment in full of the imposed civil penalty.
The violation involves failure to maintain the required availability of two independent Nuclear Service Water System loops. Duke Power management recognizes the importance of identifying and correcting the root cause of component failures to.
assure the availability of cystems required for the safe operation of Catawba Nuclear Station. The corrective actions planned to avoid further violations in this area will be fully evaluated for implementation at all of the Duke nuclear stations.
I declare under penr y 4 oerjury that the statements set forth herein are true and correct to the best c iwledge.
Very truly yours, t
hh M.S. Tuckman
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U.S. Nuclear Regulatory Commission May 27,1993 Page 2 xc:
S.D. Etlneter Regional Administrator, Region ll R.E. Martin, ONRR R.J. Freudenberger Senior Resident inspector Er
DUKE POWER COMPANY CATAWBA NUCLEAR STATION REPLY TO NOTICE OF VIOLATION ENFORCEMENT ACTION 93-054 Technical Specification 3.7.4, Nuclear Service Water System, requires, in part, that at least two independent Nuclear Service Water (RN) System loops shall be operable when both units are in Modes 1, 2,3, or 4, with each loop containing two operable Nuclear Service Water pumps, associated diesel generators and flowpaths.
Contrary to the above, both loons of the Nuclear Service Water System were inoperable from August 1992 through February 25,1993, due to three of the four RN pump discharge valves being unable to open against the pump discharge pressure due to incorrect torque switch settings. This resulted in both units being operated for an extended period of time in Modes 1, 2, 3, or 4 without the required two operable flowpaths.
This is a Severity Levellli Violation.
Civil Penalty - $75,000.
RESPONSE
1.
Admission Or Denial Of Violation Duke Power admits the vinlation.
2.
Reason For Violation The reason for this violation is two-fold.
A)
An analytical model, which is based on industry accepted standards and was procured through the vendor, was used in accordance with the Catawba Nuclear Station (CNS) Generic Letter 89-10 Program on the Unit 1 Nuclear Service Water (RN) pump discharge valves (1RN-28A and 1RN-388) to determine torque setpoints for the valve actuators during the 1992 Unit 1 outage (1EOC6). When the valves were subjected to full differential pressure, they failed to go to their safety position (cpen).
Several factors used in the equations of the model appear to be non-conservative for the valves installed in these particular applications.
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DUKE POWER COMPANY CATAWBA NUCLEAR STATION REPLY TO NOTICE OF VIOLATION ENFORCEMENT ACTION 93-054 B)
Failure of the Unit 2 RN pump discharge valves (2RN-28A, 2RN-38B) to open has been attributed to a lack of detailed information in the motor operated valves (MOVs) torque switch setup procedure (IP/0/A/3820/04). The procedure enclosure (11.1) which provided a diagram of the actuator torque switch did not specify which adjustment screw was for the "open" or "close" setting and the switch does not include a clear label to indicate "open" or "close". The technician could have mistaken f asse two settings during the torque switch adjustments in July,1989.
3.
Corrective Actions.aken And Results Achieved A)
By February 26, 1993, 00:30 hours, the Unit 1 RN pump discharge valves (1RN-28A and 1RN 388) were positioned to 20 degrees open, successfully tested with the RN header downstream of the valve depressurized, and restored to operable status.
On Fet,ruary 27,1993, the Unit 2 RN Pump Discharge valves (2RN-28A and 2RN-388) were restored to operable status. The following actions were taken upon return of the unit 2 RN valves to operable status to assess implications for other valves applicable to the guidance of Generic Letter 89-10:
1)
Differential pressure testing was performed on Unit 1 RN Pump Discharge valves 1RN-28A and 1RN-38B to measure unseating and dynamic torque loads under flow and pressure conditions. The unseating and dynarmc torque loads were higher than predicted by the manufacturer sizing calculations for the valves.
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DUKE POWER COMPANY CATAWBA NUCLEAR STATION REPLY TO NOTICE OF VIOLATION ENFORCEMENT ACTION 93-054 2)
Differential pressure testing was performed on the "as found" torque switch setting (1.5 "open") position of valve 2RN-28A with the header - depressurized. Test results concluded that this valve would have been capable of.
proper operation with the torque switch setting of 1.5 with-the header depressurized, and thus considered operable since start-up.
3)
Engineering evaluations have determined that the apparent inadequacies of the torque requirement equations associated with these specific failures are limited to the Basic-in-Flow (BIF) butterfly valve. Accordingly, the torque switch settings on all BIF butterfly valves in CNS Generic Letter. 89-10 Program applications were reviewed as follows:
BIF BUTTERFLY VALVES.
WITH A
SAFETY FUNCTION TO OPEN The BIF butterfly valves in the CNS Generic Letter 89-10 Program that have not been analyzed and diagnostically set-up were verified to have their torque switch setting positioned to the maximum allowable position, as allowed by the vendor.
The BIF butterfly valves in the program that have been analyzed and diagnostically set-up have successfully passed differential pressure testing with sufficient margin.
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F-DUKE P0"NER COMPANY CATAWBA ~ NUCLEAR STATION REPLY TO NOTICE OF VIOLATION ENFORCEMENT ACTION 93-054-BlF BUTTERFLY VALVE.
WITH ' - A SAFETY-FUNCTION TO CLOSE
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The BIF butterfly valves in the CNS~ Generic Letter
- 10 Program with a safety function to close have.
been analyzed as adequate based on review of their required ' operating conditions' and the fact that -
process flow tends to assist closure of these valves.
Review of previous differential pressure test data.
further supports this conclusion of flow assistance-during valve closure.
I Furthermore, all remaining CNS. butterfly valves' in the Generic Letter 8910 Program have been evaluated with the following results:
FISHER POSI-SEAL BUTTERFLY VALVES.
O ut-of-plant independent differential pressure testing.
of the Fisher Posi-Seal butterfly valve design, which..
comprises a large portion of the CNS Generic Letter 89-10 Program butterfly valve population, has -
demonstrated that'the sizing equations and factors are adequate.
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DUKE POWER COMPANY CATAWBA NUCLEAR STATION REPLY TO NOTICE OF VIOLATION ENFORCEMENT ACTION 93-054 ALLIS-CHALMERS BUTTERFLY VALVES The torque switch settings for the Allis-Chalmers butterfly valves in the CNS Generic Letter 89-10 Program have been evaluated and are considered adequate. Those with the safety function to close are required to operate against relatively low differential press'ure conditions (generally < 5 PSID).
Those with a safety function to open have their open torque switch set to the maximum setting, as allowed by the vendor.
FISHER MARSHALLTOWN BUTTERFLY VALVES The Fisher Marshalltown butterfly valves in the program, which are installed in air systems, stroke under low differential pressure conditions (generally
< 5 PSID) and are therefore determined to be adequate because of the absence of significant differential pressure requirements above their normal static operating requirements.
On March 20,1993, valve 2RN-38B was removed and replaced with a new valve of different design and manufacturer. The new valve was a Fisher /Posi-Seal butterfly valve and was installed to permit further testing and evaluation on one of the BIF valves used in this application. The Posi-Seal valve was successfully tested under full differential pressure conditions and test data results were found to be acceptable.
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n DUKE POWER COMPANY CATAWBA NUCLEAR STATION REPLY TO NOTICE OF VIOLATION ENFORCEMENT ACTION 93-054 l
B)
On February 27,1993, it was discovered that the open-to closed and closed-to-open torque switch settings for valves 2RN-28 A and 2RN-388 were reversed. Subsequent investigation determined that the set-up reversal may have occurred in 1989. These valves were adjusted to the maximum torque switch setting of 3.0, were successfully tested with the header downstream of the valves depressurized, and subsequently declared operable.
The procedure for MOV torque switch set-up (IP/0/A/3820/04) was verified to have been revised in 1991 to provide additional detailed guidance, including graphics for torque switch
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identification and set-up.
Due to the implications of the reversed torque switch settings on the Unit 2 RN pump discharge valves (2RN-28A and 2RN-388), an l
assessment was performed to determine which other valves could i
exhibit operational problems due to a similar reversal. This review concluded that all valves in the Generic Letter 89-10 Program, subject to this concern, have been adjusted et some point following revision to the torque switch setting procedure in 1991.
This eliminated any further concern caused by the reversed torque switch settings.
l 4.
Corrective Actions To Be Taken To Avoid Further Violations Consider valve operational history during MOV analysis calculations:
e Revise MOV Review Specification by September 1,1993.
Conduct testing on the original BIF butterfly valve that was installed in application 2RN-38B:
Validation of assumptions and determination of the root cause for the higher than expected operating torques by October 1,1993.
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4 DUKE POWER COMPANY j
CATAWBA NUCLEAR STATION REPLY TO NOTICE OF VIOLATION ENFORCEMENT ACTION 93-054 e
Evaluate the appropriateness and Use of Turbulence Factors on MOV Review Calculations:
Follow, support and review the Electric Power Research Institute (EPRI) butterfly valve torque analysis and operating behavior study by June 1,1994, Conduct and conclude the Butterfly Valve Differential Pressure Testing Project with Fisher Controls - North Stonington (Posi-Seal) by June 1,1994.
Determine the'long-term disposition of the RN Pump Discharge Valves:
e Review valve test data for continued degraded performance and prioritize consequences of seat leakage to determine if replacement valves are required (pending findings of the root cause effort) by February 1,1994.
Continued operability of the remaining ti:ree original RN pump discharge valves will be verified periodically by demonstrating their ability to open under full differential pressure, until completion of the determination for valve replacements.
Re-evaluate the CNS Generic Letter 89-10 differential pressure testing e
plan:
Study the CNS Generic Letter 89-10 population and make revisions to the test candidate list as work progresses (team in place and functioning).
5.
Date Of Full Comolime Duke Power is now in full compliance.
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