IR 05000271/1993016

Insp Rept 50-271/93-16 on 931011-15.No Violations Noted. Major Areas Inspected:Insp of Util GL 89-10,motor-operated Valve Testing Program Conducted in Accordance W/Nrc Temporary Instruction 2515/109

ML20059F477
Person / Time
Site:	Vermont Yankee
Issue date:	12/15/1993
From:	Buckley M, Eapen P, Stewart J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20059F466	List: IR 05000271/1993016 ML20059F462
References
50-271-93-16, GL-89-10, NUDOCS 9401140041
Download: ML20059F477 (8)

Text

. . _ . . __

m

.

U.S. NUCLEAR REGULATORY COMMISSION

REGION I

-

REPORT /DOCKIII' NOS.: 50-271/93-16 i LICENSE NO.: DPR-28 FACILITY NAME: Vermont Yankee Nuclear Power Station ,

INSPECTION AT: Vernon, Vermont INSPECTION DATES: October 11 - 15, 1993 t

INSPECTORS: Nm $tu'xtd '1 )(C I i I lb Michael Buckley, Peactor Engineer Date

.

Systems Section, EB, DRS i

!

Gruen 00 7 n \0 \99 i 3 James Stewart, Reactor Engineer Date ,

Systems Section, EB, DRS

APPROVED BY: / EA[l C-!f3 Plackeel K. Eapen, Chief Date Systems Section, EB, DRS

l l

!

o 0 h73 PDR

_

-

l i

. >

. .;

EXECUTIVE SUMMARY  ;

l An announced inspection of the Vermont Yankee Generic Letter 89-10, motor-operated valve i testing program was conducted in accordance with NRC Temporary Instruction 2515/10 l An initial inspection of the Vermont Yankee program, conducted in July 1991, identified a .

number of areas requiring significant improvement including inconsistencies with the generic letter recommendation l The inspectors determined that Vermont Yankee had established a formal program for implementation of Generic Ixtter 89-10 requirements, including motor-operated valve design basis evaluation and testing. A lack of clear definition of responsibilities and other -

inconsistencies with the generic letter recommendations identified in the prior inspection have been resolved. Although Vermont Yankee has completed design basis reviews and testing'

for only a limited number of valves, programs and schedules were in place for completion of the generic letter program by the commitment date of May 1995. One unresolved item was identified to ensure NRC review of the Vermont Yankee resolution of pressure k)cking phenomeno Design basis tests for three MOVs were observed by the inspectors and no significant deficiencies were identified. The inspectors determined that Vermont Yankee had performed maintenance on all MOVs in the program and had employed a switch setting control program ,

o to provide reasonable assurance of valve operability prior to completion of generic letter activitie :

l l

l I

i r

l l

-_ . -

.. -

.. e -

, . ,

_ . .

l'

t

DETAILS INTRODUCTION

! On June 28,1989, the NRC issued Generic Ixtter 89-10, which requested licensees to establish a program to ensure that switch settings for safety-related motor-operated valves (MOVs) were selected, set, and maintained properly. Five supplements to the generic letter have been issued to clarify the NRC request. NRC inspections of licensee actions implementing the requirements of the generic letter and its supplements have been conducted based on guidance provided in Temporary Instruction TI-109, " Inspection Requirements for '

Generic Letter 89-10, Revision 1," which is divided into Part 1, " Program Review," and Part 2, " Verification of Program Implementation."

The NRC conducted an inspection of the MOV program at Vermont Yankee in 1991 and at that time identified several areas requiring significant improvement. These areas included weaknesses in program scope, program administration, and calculational and diagnostic evaluatio On May 26,1993, Vermont Yankee made a presentation to the NRC regarding the status of their MOV program improvements and implementation. This inspection was a review of licensee actions in response to the 1991 inspection findings as well as a verification of program implementation including a review of current MOV testing. During the inspection, valve testing was in progress and the inspectors observed testing and data analysi .0 PROGRAM STATUS Design Basis Evaluations Vermont Yankee has established the " Motor-Operated Valve Program Plan," as the governing procedure for design basis review for safety class MOVs. The scope of the program is such that all safety class 1,2, and 3 MOVs are included except those where the i

valve is electrically or mechanically disabled, or not required to change position to fulfill a safety function. The plan includes provisions for completion of design basis reviews, MOV switch and setpoint contro1, switch setting verification, and control of MOV maintenanc in 1991, Vermont Yankee named an MOV project coordinator with primary responsibility for coordination of all MOV related activities including engineering reviews, maintenance, and test pmgram administration. Since that time, the program scope and administration have been established to ensure that the recommendations of the generic letter are complete Vermont Yankee maintains a Component Testing Program Plan, which establishes the procedures and protocol for MOV testing programs, and the MOV Program Milestone Schedule, which maintains a listing of open and closed milestones for Generic Ixtter 89-10 implementation.

i

_. _ __ _ ___ '

l

A

,

Vermont Yankee had completed differential pressure reviews for all MOVs in the plant.

l These reviews estimated the worst case differential pressure for each safety-related valve and established torque and limit switch settings to ensure that safety systems would perform as designed. Additionally, each safety-related MOV in the plant had undergone at least one maintenance rebuild. Completion of this extensive valve maintenance and establishment of a program for MOV settings prior to completion of the generic letter program is considered a strength in plant engineering and maintenanc ,

I Design basis reviews to fulfill the provisions of the generic letter have been completed for the core spray system and service water systems, as well as the other valves specified to be design basis tested in the generic letter program. These reviews included functional

,

determination of valve requirements in each operating mode. An electrical review was also completed to review motor and overload sizing and to establish minimum and maximum motor torque for both degraded and overvoltage condition The system and electrical reviews were compiled into component reviews for each applicable valve and included specification of valve testing requirements. The component reviews assumed stem friction coefficients of 0.15, valve factors of 0.5 for gate valves, and actuator thrust limits based on a weak link comparison of actuator rating, weak link allowables (from valve manufacturer evaluation), and undervoltage capability of the motor. A ten percent margin for load sensitive behavior was also included in the design calculations. While the licensee had not completed a formal justification for the 0.15 stem friction coefficient, test results revealed actuators to have as found stem friction coefficients of 0.09 to 0.12. The relatively low stem friction had been attributed to an aggressive lubrication schedule for valves in the high temperature environments, periodic valve stroking, and the lubricant used by the licensee. The licensee intended to complete component level reviews for the ,

remaining MOVs in 199 l Weak link analyses have been completed for most gate valves used at Vermont Yankee. The design basis reviews considered actuator limits to be the limiting factor considering actuator rating, the calculated weak link capability, and the motor undervoltage capability. The completed design basis reviews have not considered the effects of pressure locking or thermal binding in establishing the operating requirements for the valves. The licensee stated in a I June 8,1993, correspondence with the NRC that a review of these issues would be completed by the May 1995 program end date. Vermont Yankee engineering evaluation and resolution of pressure locking is considered unresolved pending completion of the program and review by the NRC (UNR 50-271/93-16-01).

!

!

!

!

.

.

Also, the design basis reviews had not specifically included evaluations of the Limitorque 10 CFR Part 21 report regarding reduced motor starting torque at elevated temperature Using equipment qualification records, Vermont Yankee had considered this effect during an engineering review of motor torque capability and no susceptible motors were identifie The licensee stated that final system level reviews would include formal evaluation of elevated temperature effects on motor torque and the applicability to the operational requirements for valve In a June 8,1993, correspondence, the NRC granted a conditional schedule extension to spring 1995 for completion of generic letter activities. The extension was conditioned on the Vermont Yankee confirmation of torque switch settings for gate valves with low margi During the inspection, Vermont Yankee stated that the justification for schedule extension had been met by evaluation of valve calculations and adjustment of valve switch settings, as require !

l Valve Maintenance and Testing i

'

Vermont Yankee currently performs preventative maintenance of safety-related valve actuators on a five year frequency. The maintenance includes a complete maintenance i rebuild of the actuator and diagnostic testing of the valve. Valve stem lubrication for valves (

i in high temperature areas is completed approximately every eighteen months with each refueling cycle. Valves outside the high temperature area are lubricated every five years j during preventative maintenance. Additionally, valves are subjected to in-service testing !

which has been demonstrated by the licensee to improve lubrication effectiveness. The l i

inspector reviewed valve failures and as-found testing results and verified that the maintenance schedule used by Vermont Yankee was adequate to ensure valve reliabilit Vermont Yankee established a maintenance history file for valves in the generic letter ;

program. Standardized preventative maintenance and testing procedures including provisions .

for trending of valve performance were being considered by Vermont Yankee as part of [

fulfilling the maintenance rule,10 CFR 50.6 .

l The criteria established by Vermont Yankee for differential pressure testing included: l existing plant. configuration and equipment must provide at least 80 percent of design l required differential pressure and flow; in-situ dynamic conditions must be possible within i existing operating procedures using existing plant equipment, and the testing must provide a representative sampling'of valves in the various configurations. Sixteen valves were available for testing and ten of these valves were selected for initial design basis testin Vermont Yankee provided details of the MOV testing program in a January 31,1992, letter to the NR ,

.1-1

.

6 1

At the time of the inspection, valve testing had been completed on three core spray valves, two residual heat removal valves, and one service water isolation valve. A summary of the test results is provided as an enclosure to this report. Vermont Yankce intended to complete testing of four residual heat removal valves during plant operation in the spring of 199 The inspectors observed testing of core spray valves14-26A and 14-26B, and service water valve 70-20. Test briefings were observed and Vermont Yankee staff provided adequate test control. Differential pressure tests were completed with effective oversight and procedural-controls to ensure that test requirements and operating limits were observe One test weakness was identified when motor leads for an actuator were determined to be improperly specified in the post-test restoration procedure. The work group restored the proper landing of the motor leads without properly making administrative changes to the test . j documents. When identified, Vermont Yankee supervision made the procedural revision and discussed the need for strict procedural compliance and the need to make procedural

revisions when necessary, with the work group involved in the testing activity. The event was considered by the inspectors to be of minor safety significance and the licensee's corrective actions adequate to prevent recurrenc .0 SUMMARY The inspectors determined that Vermont Yankee had established a formal program for implementation of Generic Letter 89-10 requirements, including motor-operated valve design basis evaluation and testing. The inconsistencies with the generic letter recommendations identified by the NRC in a prior MOV program inspection have been resolved.' Although Vermont Yankee has completed design basis reviews and testing for only a limited number of valves, programs and schedules were in place for completion of the generic letter program by -

the commitment date of May 1995. The inspectors determined that Vermont Yankee had'

performed maintenance on all MOVs in the program and had employed a switch setting control program to provide reasonable assurance of valve operability prior to completion of generic letter activitie .0 EXIT MEETING At the conclusion of the inspection, an exit meeting was held with Mr. R. Wanczyk and others of the Vermont Yankee staff. At the exit meeting, licensee management acknowledged the inspector findings. A list of persons contacted during the inspection is provided as Attachment I to this repor .-. - _ . _ _ _ _ _ . _. _ _-

!

i

,

r NITACHMENT 1 Persons Contacted Vermont Yankee Nuclear Power Corocration

• R. Wanczyk Manager, Vermont Yankee Station

• B. Buteau Engineering Director

• R. Pagodin Operations Superintendent

• G. Cappuccio Mechanical Engineering Supervisor ,

S. Jefferson Assistant to Plant Manager ,

• MOV Coordinator  !

T. Trask

C. Hanson MOV Engineer, Yankee Atomic !

D. Taylor Maintenance Supervisor i

i United States Nuclear Regulatory Commission

H. Eichenholz Senior Resident Inspector '

P. Harris Resident Inspector

• Denotes those attending the October 15, 1993, exit meetin .

!

. .

. .

ENCLOSURE VEIGIONT YANKEE MOV DYNAMIC TEST SUMMARY

,

, Valve Test D/P Thrust Friction Valve Stem Size Type (open- close) at CST Factor Factor Friction (close-+open) (Ibf) (open) (close) Coef (1) at CST V10-57 300 13747 0.57 0.28 (2)

4in Gate 287 4233

,

V10-66 300 4940 0.33 0.29 0.11 4in Gate 287 4196 ,

V14-11 A 385 32322 0.76 0.47 (2)

8in Gate 269 8921 ,

V70-20 122 28790 0.32 0.16 0.12 20in Gate 120 23353 V14-26A ' 301 23065 N/A 0.89 0.09 8in Globe N/A V14-26B 304 24796 N/A 0.85 0.10 .!

Sin Globe N/A (1) Reference; NP-6660D;NMAC " Application Guide for MOVs in Nuclear Power Plants" (valve disc angle not included)

(2) Torque was not obtaine NOTE: Stem Lubricant is EP-0. All valve factors were completed using orifice are t m_____..m .m. ....m.. _ _ ._._.....__ m__..__.___.._..m-__- m --__...______________m.______m_-_ _ _ _ _ _ _ _ - - _ _ - - - +=-____.----_.._-.w- . w _ - w c- -s ww-- - + - - - w-t---s -

" eo