IR 05000458/1988002

Insp Rept 50-458/88-02 on 880119-22.No Violations or Deviations Noted.Major Areas Inspected:Licensee Actions Re IE Bulletin 85-003

ML20147D220
Person / Time
Site:	River Bend
Issue date:	02/23/1988
From:	Ray Azua, Ireland R, Norman D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
Shared Package
ML20147D217	List: IR 05000458/1988002 ML20147D212
References
50-458-88-02, 50-458-88-2, IEB-85-003, IEB-85-3, NUDOCS 8803030266
Download: ML20147D220 (8)

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l APPENDIX U.S.NUCLEARREGULATORYCOMMISSION ,

REGION IV

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NRC Inspection Report: 50-458/88-02 Operating License: NPF-47 .

Docket: 50-458 ,

Licensee: Gulf States Utilities (GSU)

P.O. Box 220 St. Francisville, Louisiana 77704 Facility Name: River Bend Station (RBS)

inspection At: St. Francisv111e, Louisiana ,

Inspection Conducted: January 19-22, 1988

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Inspectors: c [ 2%#,-

D. E. Norman, Reactor Inspector, Plant Systems Mf3/88 Date

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Section, Division of Reactor Safety

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e lNbw~ f/23/b7 Date '

gMa, Reactor Inspector, Test Programs Section, Divisi n of React afety

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ng 'tihief, Plant Systems Section Date 2 '

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r K . e and, Act D s f Reactor Safety Inspection Summary Inspection Conducted January 19-22, 1988 (Report 50-458/88-02)

Areas Inspected: Routine, unannounced inspection of licensee actions related to IE Bulletin (IEB) 85-0 ,

f Results: Within the areas inspected, no violations or deviations were  !

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PDR ADOCK 050

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DETAILS 7 Persons Contacted GSU

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• J. Mead, Supervisor, Design and Electrical Engineering

• R. King, Supervisor, Nuclear Licensing

• J. Hamilton, Director, Design Engineering NRC

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• D. Chamberlain, Senior Resident Inspector

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• Denotes those present during the exit interview on January 22, 1988.

1. Inspection Summary  :

IEB 85-03, "Motor Operated Valve Comon Mode Failure During Plant  ;

Transients Due to Improper Switch Settings," expressed concerns about the proper setting of switches that control the operation of motor operated i valves (MOV). Action Item (a) of the bulletin requires that the desi i

basisfortheoperationofeachReactorCoreIsolationCooling(RCIC)gnand High Pressure Core Spray (HPCS) valve at the River Bend Station (RBS) be

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reviewed and documented; Item (b) requires that correct switch setting be

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established; Item (c) requires differential pressure testing, preferably, or other justification to demonstrate operability with settings from Item (b); Item (d) requires plant procedures that will assure the

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maintenance of correct switch settings throughout plant life; Item (e) ,

requires a written report from the licensee that reports results of

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Item (a) and contains the program to accomplish Items (b) through (d), ,

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including a schedule for completion of the items. The status of each item t is discussed below: i Items (a) and (e) - The valves to be included within the requirements of [

the bulletin, and their design basis, were based on information provided ,

by NEDC-31322, September 1986, "BWR Owners Group Report on the Operational t

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Design Basis of Selected Safety-Related Motor-0perated Valns."  ;

- Twenty-two valves, seven in the HPCS system and fifteen in the RCIC system, were determined to be applicable. The maximum expected i i differential pressure across each valve, while opening and closing, ,

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calculated from information provided in NEDC-31322, were provided by the licensee in the Item (e) submitta j Item (b) - This part of the program was initiated by first determinin l

analytically, if the operators on each of the valves to be tested were siztd correctly for their function. Once this determination was made, tne minimum and maximum closing torque switch trip settings were calculate !

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i-3-A review was performed by the NRC inspector on these. calculations to determine the methodology used and the accuracy of the results. The calculations were based on obtaining the minimum thrust needed by each valve to overcome the highest differential pressure that the valve could possibly experience. The equations used for the thrust and torque calculations were taken from Limitorque Bulletin LM-77, Appendix C, "Gate

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and Globe Valve Selection Procedure." These equations were found to be

! adequat The inputs to the calculations such as the valve and operator data, were taken from the manufacturer specification sheets. The maximum

, differential pressures across each valve were calculated as discussed in i Item (a). Both.the valve and operator data and the differential pressure calculations were reviewed by the NRC inspector. No discrepancies were identified.

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Item (c) - Valves covered by the bulletin are Limitorque operated, rising I stem gate, or globe valves. The testing was done as a joint effort

between Impell Corporation, site engineering, and site maintenance personnel. Testing was performed using the Operations Analysis and i Testing Interpretive System (0ATIS) which is an MOV signature analysis

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Actuator motor current

• Limit switch status

Torque switch status

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Valve stem thrust i Below is a list of switches involved and the concerns for their proper

setting, typical setting approaches that were taken at RBS, resolutions of

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problems identified during testing, and questions raised by the NRC l inspector concerning either as-found or as-left conditions of the switch settings, i

i Thermal Overload Relay - While this relay was not a part of the test l

' program, it can have a significant impact on MOV operability.

l Thennal overload relays are used at RBS to protect motor winding insulation from breakdown during normal operation and testing. The relays for all valves applicable to the bulletin are bypassed during

a Design Basis Accident (DBA). If the trotor is tripped by the relay i during manual initiation, the relay can be bypassed and the motor restarted by the reactor operator.

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! Torque Switch Open (TS0) - This switch is normally used to limit the i

mechanical thrust applied to a valve by the operator when stroking l the valve in the open direction. The switches were reset, when l

required, to ensure opening of the valve at thrust levels calculated

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inItem(b). In most cases, and always when valve opening is i required during a DBA, the open torque switch setting has no effect since it is bypassed during most of the opening stroke, Valve l

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j L-4-I operability was verified by a combination of analysis and by stroking  ;

the valves at or near the Delta-P outlined in the item (a) submitta ,

This portion of the switch setting program appears effective with respect to meeting valve operability objective !

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c. Torque Switch Close (TSC) - The close torque switch is normally used -

to limit valve closure thrust. Since it provides a normal control  !

function and is exercised on every closure stroke, switch setting requires more careful consideration than for the open torque switc The limiting requirement is at the end of valve travel when the thrust requirements are highest, the effect on flow control is most significant, and the switch is not bypassed. It is, therefore ,

important that the thrust at torque switch trip, envelope the most limiting thrust requirement and that margin be available to allow for ,

valve and operator degradction. Also, to be considered, at the upper "

setting limit, are valve and operator design limits and actuator  ;

motor torque limits at both rated and reduced voltage inpu '

Valves at RBS were, in most cases, tested as-found at static conditions. They were then adjusted, as required, based on thrust levels calculated in Item (b) and retested either statically, or at the DBA Delta-P or a reduced Delta-P, depending upon testing capability. The following conditions were identified during the NRC inspection for which complete information could not be provided:

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Evaluations concerning the operability and reportability of the

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following valves in the as-found condition were either not

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E51*F063 (Inboard Main Steam Isolation Valve) - The minimum

! thrust requirement calculated for the valve was 22,092 lbs.

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The torque switch tripped the motor at a closing thrust

! (safety function direction) of 11,500 lbs. The spring pack j was found to be defective and was replaced.

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- E51*F076 (line warming valve) - This valve experienced a

! torque switch trip problem and possible abnormal spring l pack behavior which prevented taking as-found thrust

measurements. The operator was overhauled and the torque j switch was replaced.

l - IFW-7A and IFW-7B were not within the bulletin testing i scope; however, they were tested because of past problems, ( including loosening of the mount bolts. Valve IFW-7A was

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found to have an excessively high closing torque. The

! 0ATIS system measured 567,000 lbs. versus an operator j design limit of 250,000 lbs.; however, the measurement was i

well outside the range of the instrumentation; therefore.

l actual thrust was unknown. The thrust switch setting on l

valve 1FW-78 was lowered prior to the test, therefore, the j as-found condition was unknow The attuator produced i

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245,000 lbs. of thrust at torque switch trip for the  ;

e reduced setting. Hydraulic lock was indicated on both i operators; thereforc, a modified spring pack, which is i designed to prevent hydraulic lock was installed. The  ;

torque switch on 1FW-7A was also found out of balance and  :

in a cocked positio .

In order to determine possible valve or. actuator damage, i the valve and actuator for IFW-78 were examined by >

nondestructive examaination (NDE) and found to be-acceptable. 1FW-7A was not examined since a comparison of  !

mounting bolts showed that IFW-7B had received the most stress. In the NRC inspector's opinion, a valid comparison  ;

of the mounting bolts can be made only by knowing the  !

service conditions of the bolts (i.e., time in service, numberofcycles,systemconditions,etc.). This ,

information was not available during the inspection; i therefore, it is uncertain if the valve and actuator inspected represented the worst case condition The as-found conditions discussed above with respect to .

' valves E51*F063, E51*F076, IFW-7A, and 1FW-78 are  !

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considered to be unresolved pending further review by the L

licensee (458/8802-01).

As previously stated in Item (c), paragraph (3), one upper  !

limit for setting a closed torque switch is the torque ,

limit of the actuator motor. If the torque switch is set  ;

at a higher torque than the motor can develop, the motor  !

will continue to run after the valve has seated and motor insulation can be damaged, or the thermal overload will I trip if it has not been bypassed. During the NRC  !

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inspection, several operators were identified which had the

"Closed" torque switch settings higher than the calculated ,

available thrust at a reduced operator voltage of i 80 percent. The following valves were identified: 7 i

- E22*F004 (HPCS Injection) - Calculated maximum i available thrust was 45,760 lbs., TSC set at l 47,910 lbs.; safety function is both opening and  !

closin E22*F012 (HPCS Min. Flow) - Calculated maximum  !

available thrust was 13.394 lbs., TSC set at [

18,200 lbs., safety function is both opening and i closin l

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E51*F064 (RCIC Outboard Steam Isolation) - Calculated ',

maximum available thrust was 26,972 lbs, TSC set at 28,220 lbs.; safety function is closing direction, k

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- E51*F068 (RCIC Steam Discharge) - Calculated maximum available thrust was 10,889 lbs., TSC set at 12,630 lbs.; safety function is closing directio E51*F076 (RCIC Line Warming) - Calculated maximum available thrust was 3,636 lbs., TSC set at 3,650 lbs.; safety function is closing directio E51*F077(RCICVacuumBreaker)-Calculatedmaximum available thrust was 3.200 lbs., TSC set at

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3,920 lbs.; safety function is closing directio The licensee has indicated that the method used for calculating maximum available thrust should yield conservative values and that potential problems discussed above may not exist. This item is considered unresolved (458/8802-02) pending refinement of the calculations, and comparison with TSC settings and resetting of the switches, if necessary, d. Open Limit Switch - The open limit switch is normally taken from the No. 4 contacts on the Limitorque geared limit switch open rotor. It provides the control function for the upper limit of valve stem i travel in the open direction and stops the valve operator motor at i the proper time to assure proper valve stroke. This suitch should i prevent backseating which experience has shown to have caused valve stem shearing, stem thread twisting, or valve bonnet metal working which results in possible stem scoring and packing blowout. It is necessary to set the open limit switch away from the backseat with j margin to allow for motor contactor dropout time and inerti !

Independent verification should be done to assure the switch has been properly se The open limit switch has been used in some instances to adjust the l plant Technical Specification stroke time limits. This practica is !

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questionable since the stroke time is adjusted by stopping the valve before it is fully open, Valves at RBS were adjusted so that the open limit switch removes power to the actuator motor when the valve is approximately 95 percent open. Verification of proper setting, to assure against backseating, is determined by rotating the handwheel in the open direction to determine if the valve has coasted against the backsea If the handwheel cannot be rotated, the switch is readjusted to achieve a proper settin !

Procedures at RBS do not permit backseating and require that the open limit switch be adjusted to eliminate backseating when discovere However, the procedures do not quantify backseating and no criteria j are established for mair.tenance personnel to identify inspection j requirements for valves found to be backseating when as-found testing of valves is performed. As-found testing identified the following ]

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-7-valves to be backseating from a slight to a severe amount: E22*F011 E22*F012, E51*F064, and E51*F028. The open limit switches were adjusted to eliminate backseating; however, no analysis or inspections were performed to detennine possible valve damage due to backseating. The lack of procedures identifying inspection and acceptance criteria for backseating of valves, and whether or not the valves identified above should have been analyzed or inspected, is considered unresolved (458/8802-03) pending analysis by the license e. Close Limit Switch - Closed limit switches are not used on rising stem valves at RB f. Open Torque Switch Bypass - When an open torque switch is used, bypass 119 the switch during the initial portion of the open stroke is required so that the switch will not prematurely stop valve travel due to the high torque condition required for initial valve movemen There is no specific requirement for the amount of valve travel during which the torque switch should be bypassed, so long as the initial high torque requirement has been bypasse Data reviewed by the NRC inspectors showed that the open torque switch was bypassed for the majority of the open stroke for most operator This should assure that valve; will open against the high unseating thrust even if the torque switch does trip. Data for four valves indicated open torque switch bypass settings of 0.7. 3,1, and 2.7 percent of valve stroke. While not verified by the NRC inspector, control of the open indicator lights and open torque switch were apparently provided by the same roto This would <

preclude adjusting the bypass without causing the indicator light to give a false indication of valve position. It was stated by GSU that a process was underway to change open bypass settings to 10 percen It was also stated that the bypass switches were being moved to another rotor which is independent of the position indicatio Justification for the acceptability of the low bypass settings was stated to be that the safety function is in the open direction, or that the valves are globe type for which the valve differential pressure tends to assist valve opening. This item will be reviewed in more detail from the final licensee report or by another inspection, if needed (0 pen Item 458/8802-04).

g. Close Torque Switch Bypass - The close torque switch bypass acts in the same manner as the open torque switch bypass; however, it normally bypasses the torque switch during the lightest duty portion of the strok It is not required to get the valve stroke started unless the valve has been backseated during the opening strok The closing torque switches at RBS are bypassed from the fell open to the 5 percent open position. The torque switch is only active during the last 5 percent of valve movement; this assures that the valve is seated with the proper amount of thrus . - - - - - - - .,

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-8-Item (d) - The following procedures, which discuss various aspects of Limitorque operator maintenance, were reviewed by the NRC inspectors:

CMP-1253, November 25,1987, "Limitoruge Motor Operated Valves"

CMP-1252, July 2, 1985, "Limitorque Operator Overhaul" PMP-1205, October 15, 1986, "Motor Operated Valve Routine Maintenance" These procedures, with the exception of the backseating question discussed in paragraph 2.d. should assure proper switch settings and valve operability throughout plant lif . Unresolved Items Unresolved items are matters about which more information is required in order to ascertain whether they are ecceptable items, items of noncompliance, or deviations. Three unresolved items identified during the inspection are discussed in paragraphs 2.c and . Exit Interview An exit interview was conducted on January 22, 1988, during which time results of the inspection were reviewed with members of the GSV staff.

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