View source for Information Notice 1994-18, Accuracy of Motor-Operated Valve Diagnostic Equipment (Responses to Supplement 5 to Generic Letter 89-10)

{{Adams
| number = ML031060610
| issue date = 03/16/1994
| title = Accuracy of Motor-Operated Valve Diagnostic Equipment (Responses to Supplement 5 to Generic Letter 89-10)
| author name = Grimes B
| author affiliation = NRC/NRR
| addressee name = 
| addressee affiliation = 
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| license number = 
| contact person = 
| case reference number = GL-89-010
| document report number = IN-94-018, NUDOCS 9403100159
| document type = NRC Information Notice
| page count = 9
}}
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                                         UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 March 16, 1994 NRC INFORMATION NOTICE 94-18:   ACCURACY OF MOTOR-OPERATED VALVE DIAGNOSTIC

EQUIPMENT (RESPONSES TO SUPPLEMENT 5 TO

GENERIC LETTER 89-10)

==Addressees==
All holders of operating licenses or construction permits for nuclear power

reactors.

==Purpose==
This information notice is intended to alert addressees to information

submitted by various nuclear power plant licensees related to the accuracy of

motor-operated valve (MOV) diagnostic equipment. The information was

submitted in response to Supplement 5, "Inaccuracy of Motor-Operated Valve

Diagnostic Equipment," to Generic Letter (GL) 89-10, "Safety-Related Motor- Operated Valve Testing and Surveillance." It is expected that recipients will

review the information for applicability to their facilities and consider

actions, as appropriate, related to operability of MOYs. However, suggestions

contained in this information notice do not constitute NRC requirements;
      therefore, no specific action or written response is required.

Background

In GL 89-10 (June 28, 1989), the NRC staff asked holders of operating licenses

and construction permits for nuclear power plants to provide additional

assurance of the capability of safety-related MOVs and certain other MOVs in

safety-related systems to perform their intended functions by reviewing MOV

design bases, verifying MOV switch settings initially and periodically, testing MOVs under design-basis conditions where practicable, improving

evaluations of MOV failures and necessary corrective action and trending MOV

problems. The NRC staff issued several supplements to GL 89-10 to clarify or

modify its recommendations.

As an integral part of most GL 89-10 programs, licensees are relying on MOV

diagnostic equipment to provide information on the thrust required to open or

close the valve, as well as the thrust delivered by the motor actuator. The

various types of MOV diagnostic equipment estimate stem thrust using different

methods, such as spring pack displacement or strain in the stem, the mounting

bolts, or the yoke. Because some licensees make decisions regarding the

operability of safety-related MOVs on the bases of diagnostic equipment

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''-IN 94-18 March 16, 1994 thrust readings, the accuracy of MOV diagnostic equipment can have a

significant effect on the safe operation of a nuclear power plant.

During the implementation of GL 89-10, the NRC staff became aware of new

information on the accuracy of MOV diagnostic equipment. This new information

raised a generic concern regarding the reliability of the data produced by MOV

diagnostic equipment. For example, on February 3, 1992, the MOV Users Group

(MUG) of nuclear power plant licensees released "Final Report - MUG Validation

Testing as Performed at Idaho National Engineering Laboratories" (Volume 1).

The report stated that the MOV diagnostic equipment that relied on spring pack

displacement to estimate stem thrust was not as accurate as its vendors

claimed. In addition, the NRC staff learned that specific MOV diagnostic

equipment that relies on valve yoke strain to estimate stem thrust was less

accurate than had been previously reported.

On March 2, 1992, the NRC staff held a public meeting with representatives of

ITI-MOVATS to discuss the accuracy of the ITI-MOVATS thrust measuring device

(TMD) to estimate stem thrust on the basis of spring pack displacement. At

this meeting, the representatives of ITI-MOVATS described the results of their

field validation program which showed that, in some instances, the TMD may be

less accurate than licensees had assumed. The ITI-MOVATS representatives also

discussed the results of their activities to resolve concerns about the fact

that the TMD is calibrated in the valve opening direction, although it also is

used to predict the thrust delivered by the actuator in the valve closing

direction. ITI-MOVATS prepared Engineering Report 5.2 (March 13, 1992) to

provide guidance to its licensee customers for evaluating the capability of an

MOV to perform its safety function under design-basis conditions in light of

the decreased accuracy of the TMD. The Nuclear Management and Resources

Council (NUMARC) developed guidelines for licensees to use in evaluating MOVs

that had been set up using the TMD.

ASEA-Brown Boveri (ABB) Impell manufactures MOV diagnostic equipment (known as

OATIS) that relies on spring pack displacement to estimate stem thrust.

Following the release of the MUG report, Impell representatives stated that

they would be working with their licensee customers to develop new accuracy

values.

Liberty Technologies has manufactured MOV diagnostic equipment, referred to as

valve operation test and evaluation system (VOTES), that estimates the thrust

required to open or close a valve based on the strain of the valve yoke.

The VOTES system does this by measuring the diametral strain (the change in

diameter) of the valve stem for a given yoke strain. The stem thrust is then

calculated using the diametral strain and the nominal engineering properties

of the stem. This stem thrust is compared to the yoke strain to provide a

correlation between the yoke strain and the stem thrust. Once this

correlation has been established, the stem thrust can be more easily

determined by measuring the yoke strain. On October 2, 1992, Liberty

Technologies notified the NRC, in accordance with 10 CFR Part 21, that it had

found two new factors that can affect the thrust values obtained with its

VOTES equipment. Those factors are (1) the possible use of improper stem

\-'IN 94-18 March 16, 1994 material constants and (2) the failure to account for a torque effect when the

equipment is calibrated by measuring the strain of the threaded portion of a

valve stem.

In its October 2 submittal, Liberty Technologies provided guidance to

licensees for correcting the thrust data by performing hand calculations, and

stated that the new Version 2.3 of its VOTES software would be of help in

performing the corrections.

On June 28, 1993, the NRC staff issued Supplement 5 to GL 89-10 requesting

licensees and construction permit holders (1) to re-examine their MOV programs

and to identify measures taken to account for uncertainties in properly

setting valve operating thrust to ensure operability and (2) to evaluate the

schedule necessary to first consider the new information on MOV diagnostic

equipment inaccuracy and then to take appropriate action'in response to that

information. Within 90 days of receipt of Supplement 5 to 4L 89-10, licensees

were required (1) to notify the NRC staff of the diagnostic equipment used to

confirm the proper size, or to establish settings, for safety-related MOVs, and (2) to report whether they had taken actions or planned to take actions

(including schedule) to address the new information on the accuracy of MOV

diagnostic equipment.

==Description of Circumstances==
The NRC staff has reviewed the responses to Supplement 5 to GL 89-10 submitted

by licensees and construction permit holders. The staff has found that, for

the most part, licensees and permit holders have been actively addressing the

uncertainties regarding the accuracy of MOV diagnostic equipment. The newly

recognized reduced accuracy of MOV diagnostic equipment can raise questions

regarding (1) the adequacy of torque switch settings to provide sufficient

thrust while not exceeding thrust or torque structural limits and (2) the

capability of actuator motors with the present settings. In their responses, licensees and permit holders indicated that many MOVs had the potential for

underthrusting or overthrusting as a result of the less-than-expected accuracy

of MOV diagnostic equipment. Consequently, some licensees reported that MOVs

have been retested, adjusted, or modified to resolve the concerns regarding

the accuracy of MOV diagnostic equipment. The staff will discuss specific

aspects of the response to Supplement 5 to GL 89-10 with individual licensees

during future inspections.

The following is a summary of the issues relating to the accuracy of MOV

diagnostic equipment as reported by licensees in their responses to

Supplement 5 to GL 89-10.

1. ITI-MOVATS Engineering Report 5.2 discussed the calibration of the ITI-
     MOVATS TMD in the open direction with reliance on the calibration to

measure thrust in the close direction. This ITI-MOVATS report focuses on

accuracy corrections for the TMD under static test conditions. The NRC

staff knows of no ITI-MOVATS guidance related to accuracy corrections for

the use of the TMD under dynamic test conditions.

IN 94-18 March 16, 1994 2. The temporary installation of the ITI-MOVATS torque thrust cell (TTC) for

diagnostic testing can affect the actuator output thrust. ITI-MOVATS

Special Test Report 6.0 addresses the actuator repositioning effect. The

licensee of the Oyster Creek Nuclear Power Plant stated in its response to

Supplement 5 to GL 89-10 that this special test report indicates that ITI-
     MOVATS recommends that actuator repeatability values and thrust/torque

measurement error values be revised when using a temporarily installed

TTC.

3. The torque effects and the material characteristics that are relevant to

the use of the Liberty Technologies' VOTES diagnostic equipment is

discussed in this company's Part 21 notification of October 2, 1992.

4. In addition to the issues involving torque effects and material

characteristics, Liberty stated in its Part 21 notification of October 2,
     1992, that (a) incorrect thrust readings can arise with the use of long

cable lengths between the signal conditioning box and the breakout box

when calibrating a VOTES sensor with a U-clamp or D-clamp; (b) under

certain conditions, one or more of the four operational amplifiers in the

breakout box oscillates and causes a thrust indication which can be lower

or higher than actual by a factor of about two or four; and (c) CB 23-100
     cables were mistakenly shipped without the offset resistor (which results

in a lower-than-actual torque indication from the VTC load cell).

5. The licensee of the Cooper Nuclear Power Plant reported in its response to

Supplement 5 to GL 89-10 that Liberty Technologies is evaluating the issue

of calibration of its equipment in one direction and reliance on thrust

measurements in the other direction.

6. The Cooper licensee reported that Liberty Customer Service Bulletin

CSB-030 (May 6, 1993), 'Proximity Probe Type Calibrators With a Possible

3% Shift in Sensitivity," alerts VOTES users to possible changes in the

sensitivity of the proximity probe-type calibrator that can overpredict

thrust readings.

7. The licensee of the Susquehanna Nuclear Power Station reported in its

response to Supplement 5 to GL 89-10 that factors that can affect VOTES

accuracy are (a) the change in stem transition areas resulting from

Liberty Technologies' refinement of its finite element model, (b) changes

in effective stem diameters, (c) the need to differentiate between General

==Purpose==
ACME and Stub ACME threads when determining torque correction

factors and effective stem diameters, and (d) new accuracy values based on

torque correction values and percent extrapolation beyond calibration

ranges.

8. The licensee of the Maine Yankee Nuclear Power Plant noted in its response

to Supplement 5 to GL 89-10 that it had submitted a notice in accordance

with 10 CFR Part 21 on July 21, 1993, regarding its determination that the

accuracy cited by Liberty Technologies for its VOTES equipment is only

IN 94-18 March 16, 1994 appropriate for torque switch trip when the Best-Fit-Straight-Line (BFSL)
     calibration method is used. As a result of this question regarding the

accuracy of the VOTES calibration method, the Susquehanna licensee

reported that its diagnostic tests will need to be repeated using the BFSL

calibration method. Liberty Technologies is in the process of issuing a

customer service bulletin that will give guidance on the inaccuracies of

the results obtained by using the BFSL method. The service bulletin will

also include a summary of a statistical analysis that was done to verify

the accuracy of the BFSL method.

===Related Generic Communications===
The NRC has issued other generic communications on the accuracy of MOY

diagnostic equipment. For example, the NRC issued Inforpation Notice (IN)
92-23, "Results of Validation Testing of Motor-Operated Valye Diagnostic

Equipment," to alert licensees to the potential decreased accuracy of MOV

diagnostic equipment manufactured by ITI-MOVATS and ABB Impell; and IN 93-01,
"Accuracy of Motor-Operated Valve Diagnostic Equipment Manufactured by Liberty

Technologies.'
This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts:   Thomas G. Scarbrough, NRR

(301) 504-2794 Allen G. Hansen, NRR

(301) 504-1390
Attachment:

===List of Recently Issued NRC Information Notices===

Attachment

IN 94-18 March 16, 1994 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information                                   Date of

Notice No.             Subject                 Issuance    Issued to

94-17          Strontium-9O Eye Appli-         03/11/94    All U.S. Nuclear Regulatory

cators: Submission of                       Commission Medical Use

Quality Management Plan                     Licensees.

(QMP), Calibration, and

Use

94-16          Recent Incidents Resulting      03/03/94    All U.S. Nuclear Regulatory

in Offsite Contamination                    Commission material and fuel

cycle licensees.

94-15          Radiation Exposures during      03/02/94   All U.S. Nuclear Regulatory

an Event Involving a Fixed                  Commission licensees author- Nuclear Gauge                               ized to possess, use, manu- facture, or distribute

industrial nuclear gauges.

94-14           Failure to Implement           02/24/94    All holders of OLs or CPs

Requirements for Biennial                  for nuclear power and non- Medical Examinations and                   power reactors and all

Notification to the NRC                    licensed reactor operators

of Changes in Licensed                     and senior reactor

Operator Medical Conditions                 operators.

92-36,          Intersystem LOCA               02/22/94    All holders of OLs or CPs

Supp. 1        Outside Containment                         for nuclear power reactors.

94-13          Unanticipated and Un-           02/22/94    All holders of OLs or CPs

intended Movement of                       for nuclear power reactors.

Fuel Assemblies and

Other Components due to

Improper Operation of

Refueling Equipment

94-12          Insights Gained from            02/09/94    All holders of OLs or CPs

Resolving Generic                           for nuclear power reactors.

Issue 57: Effects of

Fire Protection System

Actuation on Safety- Related Equipment

OL - Operating License

CP = Construction Permit

' IN 94-18 March 16, 1994 appropriate for torque switch trip when the Best-Fit-Straight-Line (BFSL)
     calibration method is used. As a result of this question regarding the

accuracy of the VOTES calibration method, the Susquehanna licensee

reported that its diagnostic tests will need to be repeated using the BFSL

calibration method. Liberty Technologies is in the process of issuing a

customer service bulletin that will give guidance on the inaccuracies of

the results obtained by using the BFSL method. The service bulletin will

also include a summary of a statistical analysis that was done to verify

the accuracy of the BFSL method.

===Related Generic Communications===
The NRC has issued other generic communications on the accuracy of MOV

diagnostic equipment. For example, the NRC issued Information Notice (IN)
92-23, "Results of Validation Testing of Motor-Operated Valve Diagnostic

Equipment," to alert licensees to the potential decreased accuracy of MOV

diagnostic equipment manufactured by ITI-MOVATS and ABB Impell; and IN 93-01,
"Accuracy of Motor-Operated Valve Diagnostic Equipment Manufactured by Liberty

Technologies."
This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below.

Odgfnal igned by

Brian K. Grimes

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts:      Thomas G. Scarbrough, NRR

(301) 504-2794 Allen G. Hansen, NRR

(301) 504-1390
Attachment:

===List of Recently Issued NRC Information Notices===
*SEE PREVIOUS CONCURRENCE

OFFICE   DE/EMEB*          OGCB/DORS*        *TECH ED       DE/EMEB*          C:DE:EMEB

NAME     AGHansen          DCKirkpatrick     RSanders      TScarbrough        JNorberg

DATE    J_01/31/94       I01/27/94 _         01/494 i1.A-
                                                              01/31/94        101/31/94 D:DE/NRR*     I AC:OGCB/DORS*
  WHodges         AJKugler           JA    IIII

02/01/94        03/03/94           103/I  /94 UUMUMtNI  NAMt:     %-1W.IrN

IN 94-XX

March xx, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical Contacts:    Thomas G. Scarbrough, NRR

(301) 504-2794 Allen G. Hansen, NRR

(301) 504-1390
*SEE PREVIOUS CONCURRENCE

OFFICE    DE/EMEB*       OGCB/DORS*      *TECH ED     DE/EMEB*        C:DE:EMEB

NAME     AGHansen       DCKirkpatrick   RSanders     TScarbrough     JNorberg

DATE    J01/31/94     101/27/94        j01/14/94     01/31/94       I01/31/94 D:DE/NRR*      AC:OGCB/DORS      D:DORS/NRR

WHodges         AJKuglerq'-       BKGrimes  II

02/01/94       03/03/94          03/  /94 UULUMtN I N.AM :  iLUIUbb. IN

IN 94-XX

February xx, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical Contacts:          Thomas G. Scarbrough, NRR

(301) 504-2794 Allen G. Hansen, NRR

(301) 504-1390
*SEE PREVIOUS CONCURRENCE

OFFICE        -D9'M/iDB       OGCB DORS        *TECH ED     DE/EMEB tA 4    rC C

NAME          AGHans e        DCKirkpatrick    RSanders     TScarbrough      JN Xerg

DATE                 7Z

/94  D<_      /94         01/14/94     0t/.z/94       I0t/.Ti/94 D:DE/NRR             C:OGCB/DORS        D:DORS/NRR

WHodgesg            -6HMar4cus          BKGrimes

w]L      '1
  02// /94             02/  /94           02/  /94 AME AL9
        ..MA,ITNAME:
VO ..._U_                     5 ...

===DOCUM                   IL891055.1N===
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