ML20236P503

Insp Rept 99900100/98-01 on 980421-23.Noncompliance Noted. Major Areas Inspected:Review of Selected Portions of Quality Assurance Program & Implementation

ML20236P503
Person / Time
Issue date:	07/13/1998
From:	NRC (Affiliation Not Assigned)
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ML20236P478	List: ML20236P476 ML20236P496 ML20236P503
References
REF-QA-99900100 NUDOCS 9807160373
Download: ML20236P503 (10)

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U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION Report No: 99900100/98-01 i Organization: Limitorque Corporation

Contact:

Bill Miluszusky, Quality Assurance Engineer (804)528-4400 NuclearActivity: Motor-operated valve actuators, replacement parts, and services  !

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Dates: April 21-23,19E8  ;

i inspector: Bill Rogers, Quality Assurance, Vendor inspection  !

and Maintenance Branch

~ Participating Personnel: Thomas Scarbrough, Mechanical Engineering Branch  ;

Approved by: Richard Correia, Chief Reliability and Maintenance Section Quality Assurance, Vendor inspection i and Maintenance Branch Division of Reactnr Controls and Human Factors j l

9907160373 990713 l PDR SA999 ENVLMIT 99900100 PDR Enclosure 2 l

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'1 INSPECTION

SUMMARY

On April 21-23,1998, the U.S. Nuclear Regulatory Commission (NRC) performed an inspection at the Limitorque Corporation (Limitorque) facility in Lynchburg, Virginia.

The inspection was conducted to review selected portions of the Limitorque quality '

assurance (QA) program, and its implementation, which included review of applicable l programs and procedures used in the current supply of motor-operated valve (MOV) actuators, replacement parts, and services to NRC licensees. The team reviewed l activities related to motor actuator sizing criteria, including actions taken in response to related industry and NRC information,10 CFR Part 21 activities, and Limitorque's

[ conformance to customers' procurement requirements and compliance with NRC regulations.

The inspection bases were:

. 10 CFR Part 50, Appendix B, " Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants."

10 CFR Part 21, " Reporting of Defects and Noncompliance."

l The team identified two nonconformances, related to corrective actions, which are discussed in Sections 3.1 and 3.2 of this report.

l 2 STATUS OF PREVIOUS INSPECTION FINDINGS l Unresolved item (99900100/93-01-03) (Closed)

Unresolved item 99900100/93-01-03 concemed Limitorque's review of a situation,

which was identified by a licensee, regarding SMB-000 actuators with incorrectly installed SAE Grade 1 and 2 hardware. During this inspection, it was determined that the licensee had adequately addressed the situation and that Limitorque had evaluated the issue. These actions adequately addressed the Unresolved item!

however, Limitorque had not completed the corrective actions which had been determined to be required and documented during Limitorque's evaluation process.

The failure to complete the required, documented corrective actions was identified as Nonconformance 99900100/98-01-02 and is further discussed in Section 3.2 of this inspection Report.

Unresolved item (99900100/93-01-04) (Closed) l Unresolved item 99900100/93-01-04 concemed the sampling frequency used by Limitorque for accepting bar stock and tubing. Limitorque had indicated during the 1993 NRC inspection that the applicable Inspection Plan would be revised to include adequate sampling plans. During this inspection, the team reviewed inspection Plan No. 23, "Bar Stock and Tubing," dated May 24,1993, which included appropriate sampling requirements and adequately addressed the Unresolved item.

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l Unresolved item (99900100/93-01-05) (Closed) l Unresolved item 99900100/93-01-05 concerned informing licensees of errors in the l

Limitorque Efficiency Table for SMB-3 actuators. During this inspection, the team determined that Limitorque had provided the correct information to the licensees by  ;

issuing Limitorque Technical Update 93-01, "SMB-3 Gear Efficiencies," dated June 8, '

1993, which adequately addressed the Unresolved item.

3' INSPECTION FINDINGS AND OTHER COMMENTS 3.1 Limitoraue Activities Related to Motor Actuator Sizing. Soring Pack Curves. Structural Batinos. and Bolt Toraues

a. Insoection scooe  ;

i The team reviewed procedures and documentation and interviewed personnel to assess Limitorque's activities related to motor actuator sizing, spring pack curves, structural ratings, and bolt torques, and review of NRC e;1d industry information.

b. Observations and Findinas b.1 AC-Powered Motor Actuator Sizing Criteria As discussed in NRC Inspection Report 99900100/93-01 (IR 93-01), Limitorque had earlier established a standard practice for sizing motor actuators as described in its "SEL" documents (dated 1977 and earlier). According to the SEL documents, Limitorque predicted the torque output of actuators used in motor-operated valves j (MOVs) as follows: '

Actuator predicted output torque = MT x Eff x AF x OAR x DVF (referred to as the " Sizing Equation") where MT = motor torque i Eff = actuator gear efficiency I AF = application factor OAR 2: overall actuator gear ratio DVF = degraded voltage factor in the 1977-era SEL documents and more recently in its Technical Update 92-02, f Limitorque specified for sizing ac-powered motor actuators: I (1) Motor to:que to be the nominal motor starting torque, (2) Ar%ior gear efficiency to be the " pullout" gear efficiency from a table provided by Limitorque for the specific actuator size and gear ratio, (3) Application factor to be 0.9 or lower depending on the particular application, (4) Overall actuator gear ratio to be based on the particular actuator, and

, (5) Degraded voltage factor to be the square of the ratio of actual to rated motor voltage.

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l The NRC team had reviewed Limitorque's basis for the calculations during the 1993 l NRC inspection and determined that, although these assumptions were based primarily on engineering judgement and that the individual parameters in the l

ac-powered motor actuator sizing criteria had not been independently justified, the confidence in the prediction of output torque had been obtained from the success of the Limitorque criteria in sizing motor actuators for many years.

In the early 1990s, dynamic tests of MOVs by NRC licensees revealed that valve vendors had significantly underpredicted the torque and thrust (related to torque by the valve stem factor) required to operate many safety-related valves under their design-basis conditions. This determination led licensees to request that Limitorque relax certain criteria used in the sizing equation for ac-powered motor actuators, which would result in higher actuator predicted output torque. For example, in a letter to Cleveland Electric lliuminating Company dated September 17,1992, Limitorque stated that, for a particular MOV and its application, the licensee could assume 110%

of the rated motor starting torque and a "run" efficiency (up to 20 to 30% greater than the " pullout" efficiency). Similarly, a Limitorque letter dated September 24,1993, to Boston Edison Company allowed that licensee to assume "run" efficiency for another MOV and its specific application. Further, Limitorque Technical Update 93-03 (dated September 1993) allowed licensees to assume an application factor of 1.0 (rather than 0.9) where the motor voltage was less than 90% of the motor's rated voltage.

As a result of such relaxations of Limitorque's motor actuator sizing criteria, most licensees revised their MOV calculations to incorporate the relaxed criteria for all ac-powered motor actuators.

Iri 1994, concems were raised regarding the adequacy of Limitorque's relaxed criteria, used in determining the actuator's predicted output torque, to reliably predict the at+ual output torque of ac-powered motor actuators. in a paper presented by Texas Utilities Electric at an NRC/ASME Symposium on Valve and Pump Testing in July 1994 (see NUREG/CP-0137), it generally appeared that the actuator sizing method woeld only be adequate if the original sizing criteria were used with " pullout" efficiency and a 0.9 application factor assumed. At another NRC/ASME symposium in July 1996 (see NUREG/CP-0152), Commonwealth Edison Company reported that its review of available test data indicated that use of " pullout" efficiency combined with a 0.9 application factor was needed to establish a conservative lower bound for actual actuator gear efficiencies. Also, at the July 1996 symposium, the Idaho National Engineering and Environmental Laboratory (INEEL) reported that preliminary results of NRC-spon'sored tests similarly suggested the need to use " pullout" efficiency combined w4h a 0.9 application factor to reliably predict the actuator gear efficiency:

On August 21,1996, the NRC issued Information Notice (IN) 96-48, " Motor-Operated Valve Performance issues," which alerted licensees to these results of NRC-sponsored and industry tests of motor actuator torque output. In July 1997, the NRC issued NU REG /CR-6478, " Motor Operated Valve (MOV) Actuator Motor and Gearbox Testing," which described in detail the results of the NRC-sponsored tests of motor '

actuator performance. The testing program revealed that motor output was typically greater than nominal starting torque but that actual actuator efficiency was normally less than "run' efficiency (and in some cases even less than " pullout" efficiency), and 4

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motor output under degraded voltage conditions was less than predicted by the square of the voltage ratio.

Duiing this inspection, the team determined that Limitorque had received the information concerning ac-powered motor actuator performance, as discussed in NUREG/CP-0137, NUREG/CP-0152, IN 96-48, and NUREG/CR-6478, by approximately September of 1997. At an MOV Users Group meeting held in December of 1997, Limitorque had stated to NRC licensees that it was considering retracting its previous relaxation of the sizing criteria and that a documented notification would be issued in early 1998. However, at the time of this inspection, Limitorque had not yet completed an assessment or finalized a position on the adequacy of the relaxation of the criteria used in the sizing equation for ac-powered motor actuators and had not provided any information to NRC licensees. The team determined that there was significant indication that relaxing the criteria used in determining the actuator predicted output torque could result in a predicted torque which would be greater than the actual torque. The team concluded that the use of the relaxed criteria, which could potentially allow licensees to use motor actuators which had not been adequately sized, was a significant condition adverse to quality and that Limitorque had obtained information on the condition by September of 1997, but had not taken adequate corrective action or documented the condition in a corrective action program by the time of the NRC inspection in April of 1998. The team concluded that Limitorque had not taken corrective action for a significant condition adverse to quality which constituted a nonconformance to the requirements of Criterion XVI, " Corrective Action," of 10 CFR Part 50, Appendix B.

(Nonconformance 99900100/98-01-01)

Subsequent to this inspection, Limitorque prepared Technical Update 98-01 (dated  !

May 15,1998) to provide updated guidance to determine the output torque capability of an ac-powered Limitorque motor actuator. In Technical Update 98-01, Limitorque specified that, in the sizing equation, licensees should use nominal motor starting torque, " pullout" efficiency, an application factor (typically 0.9), and an exponent of two as applied to the voltage ratio. Where voltage is greater than 90% cf the motor rated voltage, Limitorque allowed licensees to eliminate the degraded voltage factor because of standard motor design characteristics. Limitorque also allowed licensees to use more optimistic assumptions than specified in Technical Update 98-01 where l actual test data or certain engineering data are available. In light of available test data, Limitorque has alerted licensees to specific motor actuators that require special attention in determining output torque capability. In addition, Limitorque has indicated that the guidelines for considering the effects of elevated temperature on motor starting torque are provided in Limitorque Technical Update 93-03.

b.2 DC-Powered Motor Act= tor Sizing Criteria The sizing equation developed by Limitorque for de-powered motor actuators in the SEL documents is similar to the equation for ac-powered motor actuators. The assumptions in the sbing equ 1 tion for de-powered motor actuators include nominal motor starting torque, applicatie n factor, " pullout" efficiency, and a degraded voltage 5

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factor where an exponent of one is applied to the ratio of actual to rated motor voltages, (Limitorque has not relaxed its guidance for sizing dc-powered motor f actuators from its SEL documents). However, initial de-powered motor test results l (INEEL tests) described in NUREG/CR-6478 suggested that a tested motor did not l produce the expected torque and that the degraded voltage effect is more severe than predicted by the ratio of actual to rated motor voltage.

At the time of this inspection, Limitorque had not documented any activities related to the information regarding the adequacy of its de-powered motor actuator sizing criteria; however, Limitorque indicated that a review of de-powered motor performance test curves had been initiated and that Limitorque had plans to diccces these curves in more ds: ail with the motor manufacturer. L!mitorque also hat, assessed the general applicability of the INEEL tests based on the age of the 'ested motor and its maintenance history. Limitorque stated that it would consider any additional information developed from follow-up INEEL tests of de-powered mc tors.

During this inspection, Limitorque indicated that the questions raised regarding its de-powered motor actuator sizing criteria would be resolved th. ough planned improvements to its corrective action program, b.3 Spring Pack Curves in IR 93-01, the NRC team noted that Limitorque was developing inforrnation to revise its curves that compared spring pack displacement to actuator output torque. During this inspection, Limitorque indicated that the work had not been completed because interest in this information had decreased as licensees typically use more sophisticated valve diagnostic equipment than in the past. Limitorque indicated that its effort would resume if a need for the information was revealed. The team did not identify any concerns in this area.

b.4 Actuator Structura: Ratings Limitorque clarified its position, previously provided in a Limitorque letter to Babcock

& Wilcox, dated July 26,1990, regarding thrust and torque delivered at the MOV torque switch setting in relation to actuator structural ratings. Limitorque indicated that it did not have a concem with thrust and torque output at the torque switch setting in terms of the actuator structural rating provided the allowable structural limits are not exceeded for the entire valve stroke based on appropriate consideration of torque switch repeatability and diagnostic equipment error. The allowable structural limits may range from 110% to 162% of the original ratings depending on a licensee's reliance on recent studies of structural capability, and the conditions and limitations associated with those studies. The team did not identify any concerns in this area.

b.5 Actuator-To-Yoke Bolt Torque i

l In Maintenance Update 89-1, Limitorque referred licensees to valve manufacturers for guidance on the proper torque value for bolting connections between the actuator base and the valve yoke. In Technical Update 92-01, Limitorque provides a specific 6  !

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torque pattern for actuator-to-yoke bolts where higher structural limits are allowed and also refers licensees to the valve manufacturers for additional guidance. During this inspection, Limitorque indicated that licensees are responsible for any differences from the guidance. The team did not identify any concerns in this area.

c. Conclusion l The team concluded that Limitorque had obtained information by September of 1997 which indicated that the use of relaxed criteria for the sizing equation for ac-powered motor actuators could result in a predicted torque which would be greater than the actual torque and that the use of the relaxed criteria could potentially allow licensees to use ac-powered motor actuators which had not been adequately sized. Limitorque  ;

had not taken adequate corrective action regarding licunsee application of relaxed '

criteria used in the sizing equation by the time of the NRC inspection in April 1998, which was identified as a nonconformance. In addition, the team determined that

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Limitorque was aware of the INEEL test results which suggested that a tested j de-motor did not produce :he expected torque and that the degraded voltage effect is I more severe than predicted, but concluded that Limitorque was taking adequate actions to address this issue. I i

3.2 10 CFR Part 21 Proaram

a. Scope i The team reviewed procedures and documentation and interviewed personnel to determine whether Limitorque had established a program meeting the requirements of 10 CFR Part 21 (Part 21) and was adequate!y implementing the program.

b. Observations e 3d Findinas b.1 10 CFR Part 21 Procedure The team reviewed Quality Assurance Procedure (QAP) 13.2, " Reporting of Defects for Safety Related Equipment," Revision 11, dated February 7,1997, which established the requirements for the identification and evaluation of deviations and for the reporting of defects to the NRC.

l Paragraphs 4.1,4.2, and 4.3 of QAP 13.2 discussed employee's responsibilities for identifying non-conforming conditions or deviations and further describes these  !

conditions as " conditions of a recurring nature,""significant conditions adverse to quality," and " substantial safety hazards." The team determined that the terminology used in QAP 13.2 did not completely agree with Part 21 which defines the term l

deviation as "a departure from the technical requirements included in a procurement

l. document" which is then evaluated to determine whether a defect or substantial i safety hazard exists. In addition, the persons reviewing the various documents which the QAP indicated were used to document the non-conforming conditions - Variation Reports (Quality Control), Field Service Reports and Customer Reported Problems l l 7 l

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(Parts Service), Limitorque Corrective Action Requests and Audit Deficiency Notifications (Quality Assurance)- would not perform the evaluations of the deviations to determine whether a substantial safety hazard exists (this was accomplished by I the Part 21 committee). Therefore, QAP 13.2 was inappropriate in describing the f conditions to be reported by QC, Parts Service, and QA as substantial safety hazards 1 (which would have required the evaluation of a deviation).

b.2 10 CFR Part 21 Program implementation l

The tea'n reviewed the Limitorque Part 21 files which documented the evaluations I performed during the period from 1993 to 1998. Lirnitorque had performed eleven evaluations during this period which concerned issues such as cracks in the frame seam weld on motors, torque switch roll pin failures, a loose set screw on a bearing locknut, failed clutch sleeves, motor seals fabricated from incorrect material, failed actuator component supplied as a replacement part, missing torque switch spacers, and potential for motor pinion key failure due to excessive torque.

1 Part 21 Evaluation No. 45 concerned the review of a Washington Public Power Supply (WPPS) Part 21 report to the NRC which discussed SMB-000 actuators with I incorrectly installed SAE Grade 1 and 2 hardware. A Limitorque memorandum dated {

September 28,1993, which documented the Evaluation No. 45 Part 21 Meeting stated "this information will be re-stated together with reference of the WPPS Part 21 l report in a Limitorque Maintenance Update with a mailing no later that 10-29-93." l The Limitorque Evaluation, dated September 28,1993, had an attached Limitorque Maintenance Update, 89-1, which indicated wh?re SAE Grade 5 and 8 hardware was to be used for the SMB actuator and identified that the corrective action was to issue an additional Maintenance Update to the nuclear industry. Limitorque had no record l of the Maintenance Update being issued to NRC licensees and indicated that it had not been issued.

Part 21 Evaluation No. 47 concerned the discrepancies in fullload revolutions per minute (RPM) on performance curves for certain Reliance motors identified to Limitorque in a Reliance Electric letter dated November 15,1993. A Limitorque ,

memorandum dated December 9,1993, which documented the Evaluation No. 47 Part 21 Meeting, stated that "the speed changes were inconsequential and therefore should not be a problem," but also stated "however, the Limitorque Nuclear Support Group will be submitting the revised Performance Curves to any nuclear utility that has previously purchased the original Perforrnance Curves from Limitorque Corporation." Limitorque Evaluation No. 47, dated December 9,1993, indicated that the deviation had been evaluated by the Part 21 Committee and determined that it was not a defect and not reportable to the NRC. However, the evaluation's corrective action stated "this data to be fumished to affected Limitorque Corporation customers."

Limitorque had no record of the revised Performance Curves being issued to NRC licensees and indicated that the revised Performance Curves had not been submitted to the utilities; however, Limitorque did restate that the speed changes were insignificant and would not affect actuator performance.

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l The team determined that for Part 21 Evaluations No. 45 and No. 47, although the evaluations were adequate, Limitorque was unable to provide documentation which showed the completion of the corrective actions specified to be accomplished by Limitorque in the Part 21 evaluation files and indicated that the actions had not been accomplished. Limitorque's incompletion of corrective actions documented to be performed in Part 21 Evaluations No. 45 and No. 47 was identified as a Nonconformance to Criterion XVI, " Corrective Actions," of 10 CFR Part 50, Appendix B. (Nonconformance 99900100/98-01-02)

c. Conclusion

The team concluded the Limitorque had incorporated the portions of 10 CFR Part 21 as required by 10 CFR 21.21(a) into the Part 21 implementing procedure, QAP 13.2, and had, in general, developed a procedure which could effectively implement the requirements of the regulation. However, the team did identify a weakness in the procedure concerning the terms used to identify deviations. In addition, Limitorque had not adequately implemented its 10 CFR Part 21 program by not the completing corrective actions which had been identified during the Part 21 evaluation process which was identified as a nonconformance.

I 4 PERSONS CONTACTED Henry Grilk, Vice President of Engineering Patrick McQuillan, Manager Nuclear /Special Projects Bill Miluszusky, Quality Assurance Engineer i

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ITEMS OPENED, CLOSED, AND DISCUSSED ltem Number lyRg Descriptions Ooened i l 99900100/98-01-01 NON No corrective action taken concerning the adequacy of the relaxation of the sizing equation criteria for ac-powered motor actuators 99900100/98-01-02 NON Corrective actions identified during the Part 21 process not completed l

l Closed 99900100/93-01-03 URI SMB-000 actuators with incorrect hardware .

99900100/93-01-04 URI Sampling frequency for bar stock and tubing 99900100/93-01-05 URI Errors in the Efficiency Table for SMB-3 actuators ]

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