ML20150C924
| ML20150C924 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/11/1988 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML20127A683 | List:
|
| References | |
| NUDOCS 8803220423 | |
| Download: ML20150C924 (2) | |
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SAFETY EVALUATION REPORT BY THE OFFICE OF SPECIAL PROJECTS EMPLOYEE CONCERN ELEMENT REPORT EN 23701 "THERMAL OVERLOAD BYPASS AND INDICATION TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR POWER PLANT. UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328 1.0 SUBJECT Category:
Engineering (20000)
Element:
Thermal Overload Bypass and Indication (23701)
The basis for Element Report EN 23701, Revision 2, dated February 2, 1987, t
was a generic applicability detennination arising from the Watts Bar Nuclear Plant (WBN) Employee Concerns program.
Specific SQN concerns were identified by both the Employee Concern Task Group (ECTG) and the Generic Concern Task Force (GCTF) when they investigated the generic concerns and were documented in Significant Condition Reports (SCR) and Nonennformance Reports (NCR).
Employee concerns:
The following specific thermal overload bypass and indication concerns were identified:
XX-85-122-024 XX-85-122-025 XX 122-026 i
WI-85-100-008 1-85-129-SQN 2.0
SUMMARY
OF ISSUES Inadequate design compliance with NRC Regulatory Guide 1.97.
(This has been interpreted as inadequate compliance with Regulatory Guide 1.106, "Themal Overload Protection for Electric Motors on Motor Operated Valves (MOV)".
3.0 EVALUATION The employee concern, raised by Black & Veath at Watts Bar Nuclear Plan (WBN),
cuestioned ccmpliance with Regulatory Guide 1.106, in that the thermal over-load protective devices (TOL) for MOys were not bypassed curing LOCA or during MSLB.
Therral overload bypass is ore of two options listed in Regulatory Guide 1.106.
The other option is to set the TOL with all uncertainties 8803220423 880311 DR ADOCK 0500 8
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. resolved in the direction of completing the safety actinn, e.g., set high, and periodically tested to confirm appropriate TOL setting.
Testing is required by Technical Specification Section 3.4.8.3 Motor Operated Valve Thernal. Over-load Protection 3.8.3.2 LCO, table of valves 3.8-2.
This allegation is not
~ substantiated at SQN.
The test requirerent tt SON for a number of valves was deleted from the Technical Specification for one of the following reasons:
MOVs which wsre permanently deriergized (nade passive) to conform with 10 CFR Part 50, Appendix R.
MOVs which were r.ot required to operate to mitigate accidents.
MOVs whose TOL were permanently bypassed because'of low voltage consicerations.
The function of a TOL is to protect against a motor locked rotor condition or.a progressive valve / motor deterioration resulting in an overload condition.
TVA has reanalyzed the circuit breakers associated with the TOL that are bypassed, to assure that they continue to previde locked rotor protection and where necessary TVA has replaced the circuit breakers.
Additionally, TVA in order to address the overload condition has implerented a MOV analysis and test system (H0 VATS).
This analysis is made at least once every 18 months and af ter major valve maintenance.
Further, to ensure detection of current imbalances and single phasing in the MOV operator preventive maintenance (PM) programs are being developed, as part of the 10 CFR 50.49 Environrental Qualification (EQ)
Program, which require that all three phase current are measured.
TVA will develop these PH procedures by the end of the Unit 2 Cycle 3 refueling outage.
The changes to the Technical Specifications were found acceptable to the NRC staff and are documented in a Safety Evaluation on that subject dated October 22, 1987.
4.0 CONCLUSION
The NRC ttaff cencludes that the licensee's investigation is adequate and the resolution of the concerns described in Element Report EN 23701, SQN, Revision 2, is acceptable.
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