ML20042C754

Survey of Valve Operator-Related Events Occuring During 1978,1979 & 1980

ML20042C754
Person / Time
Issue date:	05/31/1982
From:	Ashe F, Ellen Brown NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To:
Shared Package
ML20042C755	List: ML20042C754 ML20054J462
References
TASK-AE, TASK-C203 AEOD-C203, NUDOCS 8210120372
Download: ML20042C754 (58)

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o AE00/C203 SURVEY OF VALVE OPERATOR-RELATED EVENTS OCCURRING DURING 1978, 1979 AND 198D by the Office for Analysis and Evaluation of Operational Data May 1982

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Prepared by: Earl J. Brown Frank S. Ashe Note: This report documents results of studies performed by the Office for Analysis and Evaluation of Operational Data.

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findings and recommendations contained in this report are provided in support of other ongoing NRC activities and do not represent the position or requirements of the responsible program offices of the Nuclear Regulatory Commission.

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4 TABLE OF CONTENTS Page EXECUTIVE

SUMMARY

I 1.

HACKGROUND........................

4 1.1 AE00 Perspective on Valve Assembly Operability......................

4 1.2 Other Reviews of Operating Experience.........

5 2.

OVERVIEW 0F VALVE OPERATOR EVENTS.............

9 2.1 Val ve Operato r Events.................

9 2.2 AC and DC Motor Operator Events............

10 3.

FINDINGS AND EVALUATION..................

12 3.1 Motor Operator Events in General...........

12 3.2 Five Plants with most Torque Switch Events......

15 3.3 Torque Switch Adjustment..........

18 3.4 Other Operator Event s.................

19 4.

DISCUSSION AND RECOMMENDATIONS..............

24 4.1 Discussion......................

24 4.2 Recommendations....................

27 5.

REFERENCES........................

31 Table:

Number 1

AC and DC Motor Operator and Valve Operator Events for 1978-1980.

33 2 Plant Units with largest Number of AC and DC Motor Operator Events for 19 78-19 80..............

36 3 Plant Units with largest Number of Valve Operator Events for 1978-1980.............

37 4 Events Relating to Torque Switches............

38 5 Description of Torque Switch-Related Events and Corrective Actions for 19 78-1980............

40 6 Additional Information Concerning Arkansas 1 Torque Switch-Related Events..................

45 7 Additional Information Concerning E. I. Hatch 2 Torque Switch-Related Events..............

46 8 Additional Information Concerning Davis Besse 1 Torque Switch-Related Events..................

47 9 Additional Information Concerning Cook 2 Torque Swi tch-Rel ated Events..................

48 10 Additional Information Concerning Oconee 3 Torque Switch-Related Events..................

49 11 Description of Torque Switch Adjustment-Related Events and Corrective Actions for 1978-1980.......

50 12 Description of Limit Switch-Related Events and Corrective Actions for 1978-1980.

52 13 Description of Motor Burnout Events and Corrective Actions for 1978-1980.

55

4 EXECIITIVE SilMMARY l

This survey report on valve operator-related events provides:

(1) a brief summary of related previous reviews and recommendations developed by both the ll.S. Nuclear Regulatory Commission and industry groups; (?) a review and evaluation of events that occurred during 1978, 1970 and 1980; and (3) recommendations that would lead to appropriate definition and/or resolution of problems discernible from operating event experience during the three-year time span of the survey.

The primary source of information was licensee event reports (LERs).

The survey of LERs provided sufficient information to indicate that motor operator-related events are the greatest single category of valve operator l

events. Furt.her investigation revealed that events could he grouped in three major categories which are torque switches, limit switches, and notors.

The major findings of this survey are:

(1)

Torque switch corrective action is the largest single corrective action group which is nearly 25?, of all reported motor operator events.

(2)

Torque switches do not appear to be a dominant cause of valve assembly i noperabili ty.

The reported information suggests the torque switch I

provides an indication of symptomatic change with time in valve operability characteristics rather than a root cause of valve inoperabil i ty.

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2-(3)

Repetitive problems are occurring with valve operators.

it may occur i

on the same valve, a valve in similar service in a similar system, or a valve in similar service in a redundant train of the same system.

(4)

The plant operating staff objective appears to be a mode of finding measures to return inoperable equipment to operational status rather than to determine root causes of inoperability.

(5) Motor burnout of valve motor operators has occurred quite frequently in High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC) systems of BWR units.

The recommendations of this report are summarized as follows:

(1)

The existing recommendation or guidance to bypass thermal overload protective devices associated with safety-related valve motor operators should be reassessed.

I

(?)

Improved methods and procedures for the setting of torque switches should be developed and evaluated relative to v'alve operability and l

functional qualification under accident conditions.

4 (3)

Signature tracing techniques (such as measurement of electrical current and voltage applied to the motor or the measurement of the actual valve stem torque or thrust during valve operation) should be developed and tried on selected motor-operated valves as part of the periodic inservice testing program.

The objectives of such methods should be to utilize them as an indi:ator of changes in operability characteristics (aging, inadequate adjustment or maintenance, etc.) and a predictor of the remaining margin to failure.

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n 3-(4) The NRC staff should take positive steps to assure that adequate consideration is given to aging and margin requirements for valve assembly qualification and inservice operability.

This could be accomplished through participation in national standards activities during the development phase of the standards and, subsequently, by l

establishing appropriate staff positions when the standard is endorsed.

(5) Additional action pertaining to IE Circular 77-01, " Malfunctions of Limitorque Valve Operators" is needed because events similar to the concerns identified in the circular continue to be reported.

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1.

BACKGROUND 1.1 AE00 Perspective on Valve Assembly Operability This review is a part of an ongoing study of valve assembly operability and reliability by the Office for Analysis and Evaluation of Operational Data (AE00).

The initial emphasis has been on a review of operating experience relative to valve operators.

The primary thrust has been to review and assess operating experience relative to its applicability or implications for valve operability during performance of a safety function.

The approach has been to analyze Licensee Event Report (LER) data to identify possible trends or patterns.

Some questions under consideration are:

- Does LER data indicate whether the root cause or causes of failure was determined or was a primary goal when preparing LERs?

Are there predominant failure modes of components?

Does the data provide clues or indications relative to changes in operating characteristics (aging mechanisms) of the equipment?

Does the data indicate that conditions of operation differ from those speci fied?

Can the data for specific equipment provide information about other systems or equipment?

- Are there indications of how licensees use failure data?

- Does the data indicate that certain motor-operated valve components or combinations of components are not appropriate for use in certain specific system applications?

1.2 Other Reviews of Opeisting Experience Other actions has on operating experiences have been reported and/or have required some action by licensees.

Operating experience involving valve operators has resulted in several reviews and recommendations by both NRC and Industry groups.

Some of the relatively recent topics are as follows (References 1 through 9):

IE Circular 77-01:

" Malfunctions of Limitorque Valve Operators" IE Circular 78-16:

"Limitorque Valve Operators" IE Circular 79-04:

" Loose Locking Nut on Limitorque Valve Operators" IE Information Notice 79-03:

"Limitorque Valve Geared Limit Switch Lubricant" IE Information Notice 81-08: " Repetitive Failures of Limitorque Operator SMB-4 Motor-to-Shaf t Key" EPRI NP-241:

" Assessment of Industry Valve Problens" SAND 80-1887:

" Proceedings EPRI/ DOE Workshop Nuclear industry Valve Problems" i

Proposed Draft Regulatory Guide:

" Periodic Testing of Torque Protected Motor-Operated Valves Important to Safety (RS 801-4)"

i flVREG/CR - 1363:

" Data Summaries of Licensee Event Reports of Valves at i

ll.S. Commercial Nuclear Power Plants, from January 1, 1976 to December 31, 1978" I

IE Circular 77-01 addresses specific instances of motor-operated valves that failed to open because the torque switch activated before the valve was fully off the seat.

It was subsequently determined that each valve's control circuit contained a limit switch which bypassed the torque switch function when the valve was moving off its seat. This limit switch was out of adjustment and did not suspend the torque switch function as required.

IE Circular 78-16 identifies clutch canponent wear resulting fran manual operation of valves.

The change to motor operation fran manual operation caused wear of matching lugs because contact was made while one set of lugs was rotating and the other set was at rest.

With progressive wear, the lugs would not engage and motor actuation would not drive the valve. The normal safety function of the valve is achieved with the motor operator, but during refueling operations the valve was manually operated as a throttle valve.

As a result of a study of these occurrences, a change was made in the material hardening process for the wearing clutch components.

IE Circular 79-04 discusses several instances where locking nuts were not fastened securely in accordance with manufacturer's recommendations.

If the locking nut becomes loose, it could result in disengagement of driving splines and loss of drive to the valve stem. Although the locking nut is part of the valve actuator, it would normally be fastened by the valve manufacturer after the operator had been mounted on the valve.

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The IE Information Notices 79-03 and 81-08 identify concerns relating to the limit switch gear lubricant and the key between the motor pinion gear and motor shaft respectively.

The lubricant in question could dry out and harden with subsequent failure of brasc gears in the limit switch.

The key material for the particular operator should have been a special steel, rather than the standard steel, when this particular operator is used in specific nuclear applications.

The industry sponsored report, EPRI NP-241, is a review of valve-related problems with a small portion addressing operators.

The major conclusions pertaining to operator problems were placed in three general categories:

(1) Oversized operator, and valve inability to accept loads imposed by the opera tor.

(2) Improper sizes or settings in motor thermal overloads, circuit breaker trips or torque switches.

(3) Undersized operator failure to position the valve properly.

The Sandia Report SAND 80-1887 also concentrates on valve problems in general.

In addition, it identifies certain aspects related to operators to indicate that adjustment of valve operators is a significant portion of the maintenance time devoted to valves and that oversized operators and misadjusted limit switches are the predominant cause of numerous structural failures of valve yoke legs and valve stems.

8_

The proposed Draf t Regulatnry Guide (RS 801-4) addresses torque switches from the point of view of adverse effects on required valve assembly perf ormance.

The proposed testing would apply during plant preoperational testing, during refueling shutdowns, and -a'fter a valve is replaced or maintenance performed. This proposed regulatory guide has not been released for public comment and is currently in a hold status.

The NUREG/CR-1363 report was directed at establishing LER rates for gross risk and reliability evaluations.

A method used to summarize the data was to estimate failure rates (LER rates) for various standby and demand LER rates for selected valves in U.S. commercial nuclear power plants.

These estimates were also averaged to obtain rates for all plants provided by a specific NSSS vendor and overall rates for all pWR and BWR plants. The report also suggests caution in application of these LER rates because there may be differences between the estimates in the report and actual failure rates.

Near the completion of this study, we became aware of two separate and independent studies concerning motor operated valve experience (References 12 and 13). Reference 12 is an NRC memorandum of a review conducted by Region III and Reference 13 is a report of a study of operating experience with electrically operated valves on energency coolant injection systems of plants operated by Ontario Hydro.

The results of these reports are similar to the results in this AE0D study in that torque switches, limit switches, and motors or related factors were found to be the predominant items cited.

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2.

OVERVIEW 0F VALVE OPERATOR EVENTS 2.1 Valve Operator Events The initial search of LER files covered events on all types of valve operators (motor, air, hydraulic, etc.) in order to obtain most events.

The search approach introduced the option for ac and dc motor operators in 1978.

This study covers the three-year span 1978,1979, and 1980.

Table 1* provides a list (by plant unit) of the number of ac and dc motor operator and valve operator events over these three years.

The total number of valve operator events was 444 and of these,193 were motor operator events.

Table 2 lists ten plant units with the largest number of ac and dc motor operator events, and Table 3 lists the eleven plant units with the largest number of valve operator events during the three years.

Included in these tables is Fitzpatrick 1 (although not with the largest number of events) that was identified in Reference 10 concerning elevated failure rates for engineered safety feature (ESF) valves.

Nine plant units are common to both Tables 2 and 3.

Except for one plant, the motor operator events as a percentage of all valve operator events for a given unit range from 45 percent to approximately 77 percent.

This tends to indicate that motor operators represent the greatest single category of LER reports on operators, and prompted AE00 to review motor operator events further for possible trends or patterns.

• Tables begin on p, 33.

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2. 2 AC and DC Motor Operator Events As indicated in Table 1,193 of the 444 valve operator events were associated with motor operators. From information obtained during the search, applicable events relating to motor _ operated valves may be grouped into three categories for corrective action.

These categories are torque switches, limit switches.

and motors.

Of the 193 events, 46 involved corrective actions relating to the torque switches *, and are indicated by plant unit in Table 4.

In addition, a brief description of the events appears in Table 5.

Typical corrective actions were replacement of the switches, cleaning of the associated switch contacts and/or adjustment of the setpoint.

Based on the information obtained for these events, the dominant corrective action for this set of events was the adjustment of torque switches.

Tables 6 through 11 contain additional descriptive information concerning torque switch events for specific plants.

For the remaining two categories, 24 events involved corrective actions associated with limit switches and 19 involved motors. Corrective actions for the limit switches were replacement of the switches, cleaning of switch contacts and/or switch position adjustments.

For the motors, corrective action was the replacement of the motor in nearly all cases.

Tables 12 and 13 contain additional information concerning the specific events which relate to limit switches and motors.

• A torque switch is essentially a switch to make or break electrical contact.

For a Limitorque Valve Operator, this is accomplished by transferring linear motion of the Belleville spring, which supplies the force or torque to the valve stem, to rotational indication through a rack and pinion gear and shaf t arrangement.

Rotational motion or location on the torque switch is calibrated with the applied Belleville spring force or torque.

If rotation of the torque switch is sufficient to reach the set point, then the electrical circuit is opened. However, the torque switch does not transmit load or torque to perform its function.

It serves as a position (load or torque) indication and to open the circuit if load or torque reaches a preset valve.

i Regarding the remaining 104 events, 23 were attributed to unknown causes, 9 were attributed to personnel error and the remaining 72 were attributed to a multitude of causes (such as, blown fuse in control circuit, loose pinion

'1 gear, worn shaf t clutch and clutch gear, broken or loose wiring, inoperable brake mechanism, frozen motor bearing, loose setscrew on motor pinion, loose packing gland and so on) none of which were proportionally consistent enough to be explicitly identified as a separate category similar to the above three categories.

The 23 events attributed to unknown causes were not identified as a category since they provided no specific item or items as areas of concern, either directly or indirectly.

In this situation, it is reasonable to assign on a proportional basis at least ten of these 23 events to the three primary categories identified. Accordingly, most of the review was conducted for these three categories.

I Based on a review of the information contained in the search, it is highly questionable as to whether any of the three categories identified above in-j dicates a dominant root cause or causes of inoperable motor operator valve occurrences.

For example, it is questionable as to whether adjustments in torque switch settings indicate changes in the actual torque switch setting (i.e., the torque switch itself is the problem) or indicate changes in the amount of torque required by the valve assembly due to changes in physical condition of the valve assembly or the requirements of the fluid process which it controls.

Similar reasoning may be offered for tha limit switch and notor corrective actions (i.e., these are corrective actions at least on an interim basis and do not clearly indicate problems associated with the components).

Accordingly, based on the review of the information obtained during the search, no dominant root cause of motor operator valve inoperability could

12 -

be definitely established. However, the survey did establish that the categories identified, and possibly related items or factors, are excellent candidates for further study and may yet lead to a dominant root cause or causes for the valve inoperability concern.

1 3.

FINDINGS AND EVALUATION 3.1 Motor Operator Events in General The discussion provided in Sections 2.1 and 2.2 of this report reveals several pertinent operational experience items concerning motor operators and associated torque switches. Also, comparison of LER data with the conclusions presented by EPRI NP-241 (Reference 6) and SAND 80-1887 (Reference 7) illustrates some significant differences. However, the results of References 12 and 13 are similar to the AE00 study in terms of predominant items reported.

The AE00 survey findings are listed below.

Findings (1) Motor operator events represent approximately 45% of all reported valve operator events and range as high as 77% of all valve operator events on some plants.

This indicates that motor operators represent the greatest single category of LER reports on valve operators.

(?) From infonnation provided in the LER data base, the dominant root cause of failure or malfunction of motor-operated valves cannot he clearly determined.

(3) A review of motor operator events indicates that corrective actions associated with torque switches represent approximately 23?, of all reported k

events and are the largest single corrective action group.

These corrective actions consist of replacing the torque switch, cleaning the associated switch contacts and/or adjusting the torque switch setpoint.

(4)

In 1980, adjustment was the largest single corrective action associated with torque switches.

(5) Although torque switches are cited most frequently for corrective actions, they do not appear to be a dominant cause of valve assembly inoperability.

However, the adjustment range inherent in the torque switch makes it amenable for use as a corrective measure to restore operability to an inoperable valve.

Event reports show that torque switch adjustments (increasing or decreasing the settings) are frequently used to overcome the cited operability problem.

(6) The manner in which the torque switch is referenced, and its adjustment as a corrective action, suggests the torque switch provides an indication of symptomatic change in valve operability characteristics rather than a root cause of valve inoperability.

(7)

The LER survey data for 1978,1979 and 1980 does not indicate oversized operators causing valve damage as a problem (as mentioned in EPRI NP-241 and SAND 80-1887).

If these problems still occur, presumably they happen and are corrected prior to the time that the plant begins reporting via the LER system.

(8)

Even though there were over 400 valve operator events involving 66 plant units in the three-year period, the event data presented in Table 4 indicates

that only five plants had three or more events related to torque switches.

Thus, the data appears marginal for defining a clear trend or pattern for the group as a whole and is clearly insufficient for individual plant trends or patterns.

This does not mean that individual plants could not learn and benefit from some events, as indicated in Section 3.2.

(9) Most IE Circulars and Information Notices have identified problems related to inadequate or improper instructions or failure to follow instructions for manufacture and assembly of valve operators: while the LERs appear to indicate problems due to changes in operating characteristics for specific valves.

(10) There are indications that the IE Circula

'7-01 problem of inadequate adjustment of the limit switch to bypass the torque switch with subsequent failure of the valve to open, may still exist.

In a related manner, LERs from two BWR plants reported that bypass wiring associated with the torque switches had not been installed as indicated on wiring diagrams (see Reference 11).

(11) Most malfunctions are detected by a failure to perform during a required test.

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i (12) Since torque switch events represent nearly one quarter of all reported motor operator events, and the number is approximately double that of any other category, it appears that torque switch problems may be tenned broad based or generic in nature and potentially warrant regulatory guide coverage.

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3.? F]ve Plants with Most Torque Switch Events The five plants with the greatest number of torque switch-related events as identified in Table 4 were selected for additional study.

These plants 1

are Arkansas 1, Hatch 2, Davis Besse 1, D.C. Cook 2, and Oconee 3.

The LERs for these plants were reviewed for additional information and a brief statement of the problem and corrective action, affected system, date of the event, and LER number are shown in Tables 6 through 10.

The number of events for a given plant in these Tables may be greater than shown in Table 4 because more than one event was reported on a specific LER or an LER identified by the search referenced another LER. Also, another search was made to fill in the early months of 1978 before the search technique was implemented for ac and dc motor operators.

The information provided in the tables for these five plants seens to indicate that most problems occur in only a few systems. The system most frequently identified was the energency (or auxiliary) feedwater system for Arkansas I cod Davis Resse (both are BfiW plants).

It is also apparent that repetitive problems with the same valve occurred in both a relatively long time (years) and short time (one day to a few months). Although the occurrence may not be repetitive with a given valve, it may arise with similar valves in similar systems or a separate train of the same system.

Items 2 and 3 in Table 8 provide an example of how failure of a valve to npen in the auxiliary feedwater system was an indication of increased 1

2 dif ferential pressure across the valve caused by check valve leakage fran the feedwater system.

Although the high dif ferential pressure was eventually identified as the problem, failure of the valve to open was initially attributed to a

faulty torque switch and apparently the redundant train of the system was not reviewed. Approximately five months later, the same problem occurred in the redundant train with the corrective action being adjustment of the limit switch provided to bypass the torque switch until the valve had lifted off its seat.

This approach eliminated the valve lift-off problem, but the indication of leakage and pressure change between the systems provided by inoperability of the valve was lost.

In addition, it should be noted that, in general, there is not a specific identifiable problem that can be directly related to a given valve inoperability event which has been attributed to an inadequacy associated with the limit or torque switch.

The information in Tables 6 through 10 provides several examples that illustrate changes in valve operability characteristics that were circumvented with a return to operable status by lubrication, repacking, and adjustments (usually increases) in torque switch settings. There are several failures to operate attributed to faulty or defective torque switches, without an explanation of the failure, and one statement that a torque switch was replaced with a heavier duty design.

These five plants, which represent about 8% of the aproximately 65 operating plants, were the only plants to report more than three torque switch-related events in three years. Although there is the potential to observe some trends or patterns from these plants, it would seem unreasonable to expect individual plants to have sufficient information to perform such tasks.

The data appears to suggest that the operating plant staff objective may be to return the equipment to operational status rather than determine root causes and accordingly correct these causes.

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Findings (1) Repetitive and similar problems are occurring with valve operators. The problem may be on the same valve or a valve in similar service in a similar system or a valve in similar service in a redundant train of the same system.

(2) There is strong evidence that changes in valve operating characteristics are developing with time in service. This has resulted in adjustment of torque switches to higher (or lower) settings and appears to be a possible basis for utility maintenance personnel to conclude that a torque switch is 4

faulty or defective.

However, other factors that require adjustment of the torque switches are application and possible changing properties of the valve I

packing, wear of the Belleville springs in the drive assembly, and valve cycling.

(3) The plant operating staff objective appears to be a mode of finding corrective measures to return inoperable equipment to operational status rather than determine root causes of inoperability; i.e., a valve failed to perform correctly during a required operability test and actions were performed which resulted in the valve assembly passing the test.

(Note:

This is not intended to impugn an approach that may very well be the most effective I

use of plant retot rces.)

(4) The high rate of f ailure attributed to failed, defective, or faulty torque switches makes it difficult to identify trends, and may raise some questions concerning general understanding of the operation and function of the torque switch.

(5) Torque switch adjustment is frequently used to return an inoperable valve to operable status.

(6)

Initial motor, operator and valve component selections do not appear to take into consideration incremental changes in required operational characteristics for a valve assembly due to characteristic changes in related items, such as increased leakage of an upstream check valve or temperature and other variations in process conditions.

(7)

The number of LERs reported for valve operators may not be indicative of the number of events because more than one valve operator event may be reported in a single LER (see Table 6, items 7. 8, and 9: Table 11, items 2 and 3).

This may have an impact on component reliability estimates based on LER reports.

3.3 Torque Switch Adjustments Since torque switch adjustment was prevalent in plants with the greatest number of torque switch events, the study was expanded to review all adjustment events.

Table 11 contains events related to torque switch adjustment that do not appear in Tables 6 through 10.

It appears that torque switch adjustment may take the form of either an increase or decrease.

Items 2 and 3 in Table 11 show a sequence of four events with the same valve that appear to involve changes in operating characteristics of the valve.

The sequence of corrective actions was to lubricate the valve stem, adjust the torque switch setting, and then replace the torque switch.

Several reports are unclear about the type of adjustment (increase or decrease) that was made.

There are also several reports with torque switch settings that were too high.

In Table 11 it appears that items 6 and 7, which identify improper torque switch settings, are probably high torque switch settings because

l I.

the motor thennal overload device operated.

Most of the high torque switch settings were discovered by either motor thermal overloads or circuit breaker

trips, t

F_i_rdi ngs 2

(1) Table 11 provides additional evidence that valve operating characteristics I

dre changing during service life.

(2) Torque switch settings that are too high for service conditions do occur.

(3) The reported information on the problems and/or corrective action is frequently not sufficiently clear for use of this information in data trends and patterns analysis.

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(4) Since adjustment of torque switches are prevalent with regard to torque switch-related corrective action events, this may be indicative of inappropriate initial adjustment for these devices. This condition may also be resulting from neasures taken to preclude damage to valves and/or associated motors.

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3.4 Other Operator Events i

l One other item reported in Table 11 concerning torque switch-related problems is that of cleaning of contacts. Approximately 20% of torque switch events mention cleaning of contacts as part of the corrective action.

There generally l

is insufficient discussion in the LER to draw conclusions in this area.

f Since only selected operators are provided with heaters, it may be possible 1

that contact problems are related to noisture and/or contaminant accumulation.

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limit switch events are another item reported frequently under motor operated valves.

Table 12 is a list of 24 events over the three-year study period.

Limit switch adjustments were the corrective action in 17 (about 71%) of the 24 events. Cleaning of contacts was reported in four events as the

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corrective action.

Most of the events (70%) occurred in engineered safety systems. Although there are several limit switch events reported, the total number is only about 50% of the number of torque switch events.

Since there is a potential for nearly a factor of two or more adjustments on the limit switch canpared to the torque switch, the number of limit switch adjustments appears to be less important and was not part of a detailed review. Also, the limit switch is a position indicator and does not provide the same significance about changes in thrust reauirements as does the torque switch.

There were several motor burnouts or failures reported under operator events.

Table 13 provides a list of 19 events for the three year period.

Most l

of the events were concentrated in HPCI and RCIC systems of RWR plants.

The survey data contained only one such event which occurred at a PWR plant.

In view of this concentration of events and the potential negative consequences if this were to occur during or following an accident, we conducted additional review of this category.

This review included a limited search for motor burnout events subsequent to 1980, which resulted in at least eight additional events, and discussions with licensee and utility personnel concerning this i

category.

l The objective of this additional study was to establish a reason (s) for these j

occurrences. Some factors under consideration were undersized motors, bypassing i

of torque switches, bypassing of motor thermal overload protective devices, t

i actuation repeatability of thermal overload protective devices, improper application I

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or usage of motor operators, and inadequate valve assembly maintenance and surveillance test procedures and practices.

Based on further review of specific motor burnout events and discussions with licensee and other technical personnel concerning these events, the only factors that appear related to motor burnout are:

1) bypassing of torque switches (for the complete opening stroke distance of the valve), 2) bypassing of motor thermal overload protective devices,

3) inadequate or inappropriate actual surveillance test practices, and 4) improper usage of the motor operator.

Further consideration was not given to surveillance test practice since under actual accident conditions, it would seem unlikely that the most desirable practice could be implemented.

Although this review does not establish that bypassing of motor thermal overload devices is the sole reason for motor damage or burnout, it is clear that many of the burnout occurrences could have been precluded if properly sized motor thermal overload protective devices (see references 14 and 15 for a discussion and examples of methods to size these devices) had been instated in the attendant circuity.

Also, improper usage of the motor operator, with particular regard to duty cycle appeared to be a contributor to motor damage or burnout.

Further, i

selected stations that bypass motor thermal overload protective devices (even during surveillance testing) do not experience a lower rate of reported valve motor operator events.

This tends to suggest that, based on actual field experience, bypassing of thermal overload protective devices would not increase operability of the valve assembly on demand for surveillance testing or accident conditions.

Another aspect that surfaced in this review concerns bypassing of the motor thermal overload device and its ef fect on the circuit breaker rating. Reference 16

indicates that " Overload relays should be included to provide the necessary impedance to maintain short-circuit ratings and to protect cable."

It i

should he noted, however, that operating experience to date includes several events with circuit breaker trips in which the motor thermal overload protective device bypassed the attendant control circuitry and in such events we are not aware of any instances where the circuit breaker failed to provide the intended protection.

However, Regulatory Guide 1.106 could be modified to clarify that bypassing of motor overload protective devices should not include bypassing of their associate heating elements, since bypassing of these elements could lead to exceeding short circuit ratings of the attendant circuit breakers with resulting unacceptable circuit and other types of damages.

Finally, regarding actuation repeatability of the bimetallic thermal overload devices, the review of this area indicated these devices are repeatable for practical application purposes provided their upper temperature limit has not been exceeded and their surrounding ambient temperature remains essentially c00stant.

However, if the motor current increases significantly, the upper temperature limits of these devices can be exceeded and the trip actuation setpoint will i

tend to increase due to the associated thermal stresses which the device will l

experience.

Therefore, if the trip actuation setpoint of the bimetallic overload relay changes (increases) and motor terminal voltage along with the surrounding ambient temperature of the device has remained essentially constant, it would indicate that motor current has increased significantly to permit the motor to overcome increased mechanical load including aging mechanisms.

Findings (1) There are a few reports where torque switch contacts were oxidized or corroded.

The number of these is a small percentage of all corrective action events related to switches.

(2)

Limit switch adjustment is quite common to correct problems associated with valves that will not open, close, or isolate in the specified time limit (stroke response time).

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(3)

Valve operator notor burnout has occurred quite frequently in BWRs.

(the survey data contained only one report at a PWR plant).

(4) Most of the motor burnout events which occurred at BWR stations are in the l*CI and RCIC systems.

Some failures were reported to be caused by electro-mechanical failures of other parts and perhaps moisture.

There may be a relationship between recommendation number one in Regulatory Guide 1.106 concerning bypass of thermal overload devices and the relatively large number of motor burnouts reported. Also, there appears to be a relationship between permanent hypassing of torque switches, improper usage of motnr operators, and motor burnout occurrenc'es.

(5) Actual operating plant experience with motor operators indicates that bypassing motor thermal overload protective devices during surveillance testing has not resulted in an increased operability of the valve assembly on demand. This tends to suggest that bypassing motor thermal overload protective devices during accident conditions would not increase the operability of the valve assembly on demand.

s 1

(6) The review of selected nuclear,unitywhich are bypassing protective devices on motor operators shows that this r'ecommendation is being implemented by N..

removal of the protective device contacts from the associated control circuitry while. retaining the heater. elements within the motive power circuit.

If bypassing of the protective devices on motor operators is to be implemented, then the practica\\just mentioned is' esirable since complete bypassing of the protective devices cbuld result }nsexceeding'the short circuit rating of the attendant circuit h[eaker with resulting unacceptable circuit and other types ot' damages.

w (7) ;!f the trip actuation setpoint of a bimetallic overload relay changes and s

s Gotor teratinal voltage along with the surrounding ambient temperature of the device has remained essentially constant, it would indicate that motor current

'has tincreased significantlT to permit the motor to overcome increased mechanical s,s load including aging mechanisms.

\\

4.

DISCUSSION AND p.ECOMMENDATIONS s

~

\\

4.1 Discussion l, The findings and evaluations phase of this survey. suggests there are two general aspects that can contrib>ste to resolution of the inoperability problem of valve motor operators.

One aspect pertains to primarily technical issues that can be addressed y definitive recommenditions for action and the other addresses possible i

approaches or methods that wduld be' useful to aid in identification and definition of valve motor-operator relatet problems. The intent of the following discussion is to provide constructive illustration of approaches that would be useful in identification and definition of, problems.

Specific recommendations are provided in Section 4.2.

,s N

g

. Since each plant has only a few reported events, it is most likely that data analysis for trends and patterns is not feasible for individual licensees.

However, it would seem that a single group (national, industry, etc.) with overview cognizance could perform a valuable service with additional i

detailed review and evaluation of operational data on valve motor operator events.

Such a review could be limited to events involving torque switches, limit switches and notors together with related factors.

The objective of this review could be to explicitly identify root cause of events related to these three areas and recommend specific solutions to eliminate them.

Such a group could consist of individuals possessing detailed knowledge of valve 4

motor-operator designs, specific nuclear plant operational experience with these designs, specific surveillance and maintenance practices and procedures for these designs when they are used in a nuclear power station, and particular usage of given designs in a given nuclear power plant application.

Our per-1 ception of this group is that it would concentrate on positive actions and and recommendations to solve or Correct problems in Contrast to a response of a study group.

As an action group it would provide constructhe responses to the problems cited by References 12 and 13 and this AE0D study.

Also, based on this survey of LER data, it appears that efforts by a review group could be enhanced with additional effort on past reports and possible improvements in reporting of future events.

Some areas for consideration are:

(1 )

Individual plant units could review past reportable occurrences, if readily available, of valve motor-operator events to obtain additional detailed information with the objective of determining root cause or causes of the event.

This review should give special consideration to repetitive and similar occurrences involving the same valve, a valve in

i

. i similar service in a similar system, or a valve in similar service in a redundant train of the same system.

J (2)

Based on the frequent number of LER reports that identify or describe multiple, but independent, valve motor-operator events, and the inadequacy of the information reported, the following could be considered for future LER reports.

(a ) An LER should address a single valve motor operator event unless there is an interaction or sequential dependence between occurrences.

(b) Consistent with current reporting requirements, information reported in an LER should be explicit and factual relative to improper operation of a valve motor operator.

In particular, the report should identify the component; explain what happened; determine and discuss why it happened (if possible within a reasonable time period); identify implications for operability of the component within the system (or other components in similar or redundant trains of the system); and state the corrective action.

In addition to the preceding comments, it also seems worthwhile to mention some rather general observations resulting from this survey of valve motor-operator LER data.

First, one should exercise caution and discretion in attempting to use the number of reported LERs as a data base for component reliability estimates because this number may not be indicative of the actual number of occurrences for a component of a given type.

Further, the level of detail and the clarity j

of information provided in LERs may, in many cases, not be useful for such reliability estimates.

Second, it would seem that valve assembly operability

could be enhanced if initial valve assembly selections (motor, operator, valve components) took into consideration the possible effects on required operational characteristics due to changes in related items, such as leakage of upstream check valves, temperature and other variations in process fluids, and variable factors ;ach as gland packing tightening, lubrication, and manual operation of valves. Lastly, operational experience with motor-operated valves indicates that torque switches and/or associated related factors are relatively broad based (nearly 25% of all reported valve motor-operator events) and may warrant specific guidance, either through regulatory actions (such as a Regulatory Guide or by the Standard Review Plan) or a national standard.

4.2 Recommendations (1)

The existing recommendation or guidance to bypass thermal overload protective devices associated with motor-operator safety-related valves (even based upon the presence of an accident signal) should be reassessed to consider such factors as:

(a) Design details of the valve assembly and associated control and support electrical circuitry.

(b)

Specific valve assembly use in a particular system (or systems) or expected usage during and following transients or accidents.

(c) Evaluation of whether the bypass is effective in providing the desired valve operability compared to the potential for increased motor, valve and/or attendant component damage with a commensurate reduction in safety.

' While the intent of the bypass recommendation may be appropriate from a safety viewpoint for certain motor-operated valves in specific system applications, it is equally clear from operational experience that it is not desirable (also from a safety viewpoint) for other applications. The operational experience supports a strong relationship between the ilypassing of these devices, electrical motor burnout events, valve and attendant component damage, and/or associated perturbations in the supporting electrical system. The latter item may possibly be more significant with respect to safety.

Further when these factors are considered, it may be desirable to modify Regulatory Guide,1.106, " Thermal Overload Protection for Electric Motors on Motor-0perated Valves," so as to emphasize implementation of recommendation C.2 including the proper sizing of motor thermal overload protective devices.

(2)

In view of the many reperted corrective actions pertaining to adjustment of torque switches, methods and procedures for initial setting of these devices should be reviewed.

Actual application experience (which may include information obtained by applying the techniques of item 3 below) should be used to identify more accurate and reliable approaches.

In addition, the initial torque switch settings, including those made during or immediately following valve assembly maintenance and subsequent adjustments, should be evaluated relative to operability and functional qualification under accident conditions:

(a) Does operability under test conditions imply a known margin exists such that the valve assembly will operate under accident conditions?

. 4 (b) When the torque switch is adjusted to permit operation under test conditions, what accountability is there to ensure that margin is adequate (the same or perhaps additional margin may be needed) for safe o,neration under accident conditions?

(3)

Signature tracing techniques (such as measurement of electrical current and voltage applied to the motor or the measurement of the actual valve stem torque or thrust during valve operatica) should be developed and tried on selected motor-operated valves as part of the periodic inservice testing program.

In addition, the developed method should be applied immediately following maintenance work on valve assemblies so as to ensure that maintenance has not adversely affected valve assembly operation. The objectives of such a method should be to utilize it as an indicator of changes in operability characteristics (aging, inadequate adjustment or maintenance, etc.) and'a predictor of the remaining margin to failure.

This approach would also assist in determining root causes of operability problems such as changes in valve operability characteristics, changes in torque switch characteristics, or changes in other factors.

Further, this method requires that accurate records for time, date, plant conditions, system conditions and actual measured value of parameters he maintained so that meaningful time / history information concerning valve assembly operability can be determined.

(4)

The NRC staf f should take positive steps to assure that adequate consideration is given to aging and margin requirements for valve assembly qualification and inservice operability. This could be accomplished through participation in national standards activities during the developmental phase of the standards and, subsequently, by establishing appropriate staff positions when the standard is endorsed.

3 e

t

- 3n -

(5)

Followup action pertaining to IE Circular 77-01, " Malfunction of Limitorque Valve Operators" should be conducted because events similar to the concerns identified in the circular continue to be reported.

I l

. t 5.

REFERENCES 1.

IE Circular 77-01, " Malfunction of Limitorque Valve Operators," dated January 4, 1977.

2.

IE Circular 78-16, "Limitorque' Valve Operators," dated July 26, 1978.

3.

IE Circular 79-04, " Loose Locking Nut on Limitorque Valve Operators,"

dated March 16, 1979.

4.

IE Information Notice 79-03, "Limitorque Valve Geared Limit Switch Luhricant," dated February 9,1979.

E.

IE Information Notice 81-08, " Repetitive Failures of Limitorque Operator SMB-4 Motor-to-Shaft Key," dated March 20, 1981.

6.

EPRI NP-241, " Assessment of Industry Valve Problems," dated November 1976.

7.

SAND 80-1887, " Proceedings EPRI/00E Workshop Nuclear Industry Valve Problems," in Washington, D.C., May 20-21, 1980, dated January 1981.

8.

Proposed Draf t Regulatory Guide, " Periodic Testing of Torque Protected Motor-0perated Valves important to Safety," (RS 801-4), Working Paper dated June 3, 1980.

9.

NUREG/CR-1363, " Data Summaries of Licensee Event Reports of Valves at U.S. Commercial Nuclear Power Plants," published date June 1980.

10.

Memorandum, W. E. Vesely to A. Thadani, " Elevated Failure Rates for ESF Valves," dated April 29, 1981.

11.

IE Circular 81-13, " Torque Switch Electrical Bypass Circuit for Safeguard Service Valve Motors," dated September 23, 1981.

12.

NRC Meme andum for E. L. Jordan from R. L. Spessard, " Motor Operated Valve Problems," dated March 25, 1981.

13.

RMEP-IR-03600-32, "NGD Operational Experience with Electrically Operated Valves on Emergency Coolant Injection Systems," dated September 1981, Ontario Hydro, Toronto, Canada.

I e

l i

i,

REFERENCES 14.

A. W. Richards and C. D. Formica, " Motor Overload Protection for Motor Protection for Motor Actuated Valves," IEEE Trans. on Power Apparatus and Systems, Vol. PAS-100, No.1, January 1981.

15.

F. D. Bar.ter, "The Dangers of Bypassing Thermal Overload Relays in Nuclear Power Plant Motor Operated Valve Circuits," F 80 260-0, a paper presented at the IEEE PES Winter Meeting, New York, N.Y., February 3-8, 1980.

16.

General Electric, GET-3101H, " Selection and Specification Guide for 7700 Plus Motor Control Centers," page 28.

17.

A. F. Kolb and H. W. Thom, " Motor Protection Characteristics of Ambient Insensitive Overload Devices," IEEE Trans. on Industry Applications, Vol. l A-15 No. 3, May/ June 1979.

o !

Table 1 AC AND DC MDTOR OPERATOR AND VALVE OPERATOR EVENTS For 1978-1980 AC and DC Valve Plant Unit Motor Operator Events Operator Events Arkansas 1 6

10 Arkansas 2 13 18 Beaver Valley 1 1

6 Big Rock Point 0

1 Browns Ferry 1 4

5 Browns Ferry 2 1

1 Browns Ferry 3 3

6 Brunswick 1 6

13 Brunswick 2 7

14 Calvert Cliffs 1 1

10 Calvert Cliffs 2 0

6 Catawaba 1 0

1 Cooper 1 6

13 i

Crystal River 3 5

7 Davis Besse 1 10 28 D. C. Cook 1 4

5 D. C. Cook 2 5

9 Dresden 1 2

2 Dresden 2 3

7 Dresden 3 3

8 Duane Arnold 5

11 Edwin liatch 1 8

13

---

.-.n r.-- - -,.-,

e i,

Table 1 (continued)

AC and DC Valve Plant Unit Motor Operator Events Operator Events l

Edwin Hatch 2 8

13 a

FitzPatrick 1

-10 15 Ft. Calhoun 1 1

3 Ft. St. Vrain 1 1

P H. R. Robinson 2 3

5 Joseph Farley 1 3

8 Indian Point 2 0

1 Kewaunee 1 2

3 Maine Yankee

?

4 Millstone 1 1

4 l

Millstone ?

0 1

Monticello 1 5

9 Nine Mile Point 1 0

2 North Anna 1 2

10 North Anna 2 0

2 C

Oconee 1

-2 2

Oconee 2 3

5 Oconee 3 4

5 I

Oyster Creek 1 2

7 Palisades 0

1 Peach Bottom 2 2

7 Peach Bottom 3 7

l 's I

l I

l

.. - -+- - - -. -.. -, - - - <.

o

-n-Table 1 (continuerf)

~

AC and DC Valve Plant Unit Motor Operator Events, Operator Events Pilgrim 1 2

9 i

Point Beach 2 1

1 Prairie Island 1 2

?

i Prairie Island 2 0

3 i

Ouad Cities 1 1

9 Ouad Cities P 5

13 Rancho Seco 1 1

?

Robert Ginna l 1

1 Salem 1 4

11 San Onofre 0

6 Sequoyah 1 4

10 St. Lucie 1 3

6 4

i Surry 1 3

5 Surry ?

4 6

Three Mile Island 1 2

3 Three Mile Island 2 2

2 i

Turkey Point 3 1

6 Turkey Point 4 0

1 Vermont Yankee 1 1

7 Yankee Rowe 0

1 3

Zion 1 2

14 j

Zion 2 3

7 4

Totals-(for 66 plant / units) 193 444 i

e O

Table 2 PLANT llNTTS WITH LAPGEST NUMBER OF AC AND DC MOTOR OPERATOR EVENTS FOR 1978-1980 Plant linit Number of Events, Arkansas 2 13 Davis Besse 1 10 FitzPatrick 1 10 Hatch 1 8

Hatch 2 8

Brunswick 2 7

Peach Bnttom 3 7

Arkansas 1 6

Brunswick 1 6

Conper 1 6

i

?

i' l

I

A 4,

Table 3 PLANT UNITS WITH LARGEST NUMBER OF VALVE OPERATOR EVENTS FOR 1978-1980 Plant Unit Number of Events Davis Besse 1 28 Arkansas 2 18 FitzPatrick 1 15 Peach Bottom 3 15 i

Brunswick 2 14 Zion 1 14 Brunswick 1 13 Cooper 1 13 Hatch 1 13 Hatch 2 13 Quad Cities 2 13 i

4

.i I

e

,.-...--.-...--.---_.-n--

Table 4 EVENTS RELATING TO TOROUE SWITCHES Plant linit nocket Number Number of Events Arkansas 1 50-313 5

Hatch 2 50-366 5

Davis Besse 1 50-346 3

D. C. Cook 2 50-316 3

Oconee 3 50-287 3

Crystal River 3 50-302 2

Kewaunee 50-305-2 Maine Yankee 50-309 2

Peach Bottom 2 50-277 2

Quad Cities 2 50-265 2

Sequoyah 1 50-327 2

Browns Ferry 3 50-246 1

Brunswick 2 50-324 1

Cooper Station 50-298 1

i D. C. Cook 1 50-315 1

Oresden 2 50-237 1

Dresden 3 50-249 1

Duane Arnold 50-331 1

Monticel10 50-263 1

1 North Anna 1 50-338 1

I Oconee 1 50-269 1

Oyster Creek 1 50-219 1

Point Reach 2 50-301 1

l l

Table 4 (continued)

Plant linit Docket Number Number of Events Quad Cities 50 754 1

St. Lucie 1 50-335 1

Surry 2 50-281 1

Totals (for 26 plant units) 46

. Table 5 DESCRIPTION OF TOROUE SWITCH-RELATED EVENTS AND CORRECTIVE ACTIONS FOR 1978-1980 Occurrence and Corrective Action Plant Unit, LER Number System and Event Date 1.

Inside containment isolation Chemical, volume Arkansas 1 seal return valve (CV-1272) for control and liquid 79-021/03L-0 RCP failed to fully close; poison system and 11/15/79 torgee switch was replaced.

controls 2.

CV-7444 Hydrogen purge supply Containment Arkansas 1 isolation valve failed to close; combustible gas 80-001/03L-0 torque switch contacts cleaned.

control systems and 1/14/80 controls 3.

CV-7448 Hydrogen purge exhaust Containment Arkansas 1 isolation valve failed to close; combustible gas 80-002/03L-0 torque switch contacts cleaned.

control systems and 1/14/80 controls 4.

Main steam supply valve (CV-2667)

Feedwater Arkansas 1 to P-7A did not fully open; system and controls 80-023/03L-0 torque switch was adjusted.

7/4/80 5.

RCS makeup block valve (CV-1234)

Chemical, volume Arkansas 1 failed to fully close; torque control and liquid 80-033/03L-0 switch was adjusted, poison system and 9/6/80 controls 6.

RCIC minimum flow bypass valve Reactor core Browns Ferry 1 FCV-3-71-34 failed to go close; isolation cooling 80-026/03L-0

'crque switch contacts cleaned, systems and 7/14/80 controls 7.

RWCU suction inboard valve Reactor coolant Brunswick 2 (F001) failed in the mid-position, cleanup system 79-078/03L-0 torque switch torqued out early:

and controls 8/31/79 valve manually shut then cycled four times.

8.

Service water valve (SW 888)

Station service Cooper 1 failed to open; replaced torque water system and 78-038/03L-0 switch (Crane Teledyne Company).

controls 12/8/78 4

41 -

i Table 5 (continued)

Occurrence and Corrective Plant tinit,LER Number Action System and Event Date 9.

RC drain tank isolation Containment Crystal River 3 valve (V-94) would not close; isolation system 80-041/03L-0 torque switch adjusted.

and controls 10/2/80 10.

Containment isolation valve Containment Crystal River 3 (CAV-3) would not close while isolation system 80-048/03L-0 sampling the pressurizer and controls 11/16/80 water space; valve stem lubricated and torque switch adj usted.

11.

RHR discharge valve (ICM-lll)

Residual heat D.C. Cook l to cold legs 2 and 3 failed removal system and 79-057/03L-0 to open completely; torque control s 10/29/79 switch removed, cleaned and lubricated.

12. CM0 414 failed to operate in Cooling system D.C. Cook 2 its prescribed time; torque switch for reactor auxiliary 78-027/03L-0 contacts were cleaned and and controls 4/22/78 adjusted.

13. Containment spray pump Emergency core O.C. Cook 2 discharge valve IMO-220 failed cooling system and 79-051/03L-0 to open; torque switch and drive control s 12/17/79 motor replaced.

14.

Suction valve (VM0-102) for the Containment D.C. Conk 2 containment equalization fan air purification 80-010/03L-0 failed to open; torque switch and cleanup system 2/16/80 adjusted.

and controls 15.

Auxiliary feedwater valve Feedwater Davis Besse 1 (AF3869) could not be closed; system and controls 70-030/03L-0 replaced torque switch with 2/20/79 one of a heavier duty design.

16.

Decay heat removal valve DH-2735 Containment Davis Besse 1 failed to close after being isolation system 79-041/03L-0 opened; valve stem closed, valve and controls 3/20/79 repacked and torque switch setting increased.

' Table 5 (continued)

Occurrence and Corrective Plant Unit, LER Number Action System and Event Date

17. Main steam inlet to AFW pump Feedwater Davis Besse I turbine 1-1 isolation valve system and 79-073/03L-0 torqued out early; torque switch controls 7/8/79 setting adjusted.

18.

HPCI steam supply valve failed Emergency Dresden 2 to open; torque switch was core cooling 80-039/0lT-0 replaced.

system and 10/11/80 control s

19. MSIV leakage control system Containment Duane Arnold outboard isolation valve isolation system 78-022/03L-0 (MOV 84028) did not close properly; and controls 4/6/78 torque switch contacts were cleaned.

20.

RCIC line isolation valve Reactor Duane Arnold MOV-2401 would not open; torque core isolation cooling 80-050/ 03L-0 switch was replaced.

system and controls 9/17/80 21.

Service water valve (2P41-F315)

Station service E.I. Hatch 2 was closed but would not reopen water system and 79-057/03L-0 electrically; torque switch and controls 6/24/79 associated contacts cleaned.

22.

Hydrogen recombiner valve Containment E.I. Hatch 2 (2T49-F003A) failed to open; combustion gas control 80-004/03L-0 torque switch was replaced, syst'em 1/18/80

23. RCIC outboard steam supply Reactor core E. I. Hatch 2 line isolation valve isolation cooling 80-055/03L-0 (2E51-F008) failed to system and controls 5/6/80 isolate; torque switch was repaired.

24.

RCIC steamline outboard Reactor core E.I. Hatch 2 isolation valve (2E51-F008) isolation cooling 80-123/03L-0 failed to close fully; torque system and controls 8/12/80 switch was repaired.

25.

Valve 2 Ell-F007A failed leak Residual heat E.I. Hatch 2 rate test; torque switch adjusted.

removal system and 80-152/03L-0 controls 11/4/80

26. Containment isolation valve Cooling system Kewaunee 1 would not shut completely; torque for reactor 78 008/03L-0 switch contacts were cleaned.

auxiliary and 2/28/78 control s

Table 5 (continued) 1 Occurrence and Corrective Plant Unit,LER Number Action System and Event Date 27.

Valve SI-351A would not open; Residual heat Kewaunee 1 open torque switch adjusted.

removal system 80-015/03L-0 and controls 3/3/80 28.

HPSI pump suction valve and Containment Maine Yankee CS-M-66 outlet valve failed heat removal system 79-006/03L-0 to operate as required; torque and controls 3/7/79 switches adjusted.

29.

MOV-QS 102A would not return C'ont ainment Nohth Anna 1 to its normal close position; air purification 78-ll5/03L-0 torque switch contacts cleaned.

and cleanup system 11/7/78 30.

3PR-9 failed to close; torque Containment Oconee 3 switch replaced and properly isolation system 78-003/03L-0 adj usted.

and controls 2/2/78 31.

RS-3 failed to open; torque Containment Oconee 3 switch replaced.

~ heat removal system 78-004/03L-0 and controls 2/3/78 32.

BS-2 failed in an intermediate Containment Oconee 3 position; torque switch replaced.

heat removal system 78-005/03L-0 and controls 2/7/78 33.

Valve V-14-37 would not close; Emergency core Oyster Creek 1 torque switch adjusted and set cooling system 78-017/03L-0 screw tighten.

and controls 9/14/78 34.

Main steamline drain isolation Main steam Peach Bottom 2 valve failed to close; torque isolation system and 78-042/03L-0 switch to be replaced.

control s 10/19/78 35.

Inboard main steamline drain Main steam Peach Bottom 2 isolation valve (M0-2-74) failed isolation system 78-030/03L-0 to close; torque switch to be and controls 6/12/78 replaced.

36.

Starter breaker overload Containment Point Beach 2 for containment spray valve heat removal system 78-007/03L-0 (2-MOV-860C) trip' ped ; torque and controls 6/16/78 switch was replaced.

~

37.

Thermal overload relay for Emergency Quad Cities 1 chamber cooling valve MD core cooling system 80-009/03L-0 1001-36B tripped; torque and controls 4/10/80 switch adjusted

a.

Table 5 (continued)

Occurrence and Corrective Plant Unit,LER Number Action System and Esent Date 38.

Valve M0-2-1402-3A would not Containment Quad Cities 2 reopen; temporary sticking of the heat removal system 80-021/03L-0 torque switch on the valve and controls 9/14/80 operator.

39.

M0-2-1001-29A initially Containment Quad Cities P failed to open fully; torque heat removal system 80-023/03L-0 switch adjusted.

and controls 10/10/80 40 1-FCV-62-136 would not Emergency core Sequoyah 1 open; torque switch adjusted.

cooling system and 80-111/03L-0 control s 6/26/80 41.

AFW puap failed to start, Feedwater Sequoyah 1 torque switch failed to systems and 80-151/03L-0 function properly causing control s 8/11/80 valve FCV-1-51 motor operator to short and thermal over-loads to melt; f.

42.

MV-07-1B failed to open; torque Emergency St. Lucie 1 switch replaced.

core cooling 78-044/03L-0 system and controls 11/21/78 43.

M0V-CW-200A failed with the Ultimate Surry 2 valve approximately 75%

heat sink 80-034/03L-0 open; torque switch replaced.

facilities 11/22/80 44.

Containment isolation valve Containment Crystal River 3 CAV-3 would not close; torque isolation system 80-053/03L/0 switch was replaced.

and controls 12/8/80 45.

HPCI steam supply outside Emergency FitzPatrick 1 No. IV operator motor failed; core cooling 80-085/0l T-0 motor rewound and torque system and 12/8/80 switch replaced.

control s 46.

Valve M03-1501-288, both Containment Dresden 3 indicating lights went out and isolation system

' 78-076/03L 0 the motor stopped; shaft pin on and controls 6/6/78 the torque switch was replaced.

1. Corrective action was not stated in the LER.

O

• Table 6 ADDITIONAL INFORMATION CONCERNING ARKANSAS 1 TOROUE SWITCH-RELATED EVENTS

• Event Date Problem and Correction System LER Number 1.

Valve CV-2667 to turbine drive failed to Emergency 01/13/78 open; torque switch defective and re-feedwater 78-002 placed.

2.

Valve CV-7449, H2 purge isolation failed Combustible 04/19/78 to torque out and bent stem; torque switch gas control 78-010 failed and replaced.

3.

Valve CV-1272 inside isolation seal Chemical 11/15/79 return line for RCP "B" failed to close; and volume 79-021 torque switch failed to make up in fully control open position and replaced.

4.

Valve CV-7444, H2 purge supply isolation Combustible 01/14/80 failed to close; torque switch contacts gas control 80-001 cleaned and valve verified opera tional.

5.

Valve CV-7448, H2 purge exhaust isolation Combustible 01/14/80 failed to close; torque switch contacts gas control 80-002 cleaned and valve verified opera tional.

6.

Valve CV-2617 failed to close remotely, Emergency 03/06/80 stem was binding; stem was repacked.

feedwater 80-005 7.

Valve CV-2667 failed to fully open; Emergency 04/06/80 lubricated stem and adjusted the torque feedwater 80-012 switch.

8.

Valve CV-2667 failed to open, stem was Emergency 04/07/80 binding; loose bolts securing operator to feedwater 80-012 body were tightened.

9.

Valve CV-2617 failed (cause and correction Emergency 04/07/80 not provided).

feedwater 80-012 10.

Valve CV-2667 failed to fully open, torqued Emergency 07/09/80 out early; torque switch given a small feedwater 80-023 adj ustment.

11.

Valve CV-1234 failed to close (block Chemical 09/06/80 valve in makeup system) due to high and volume 80-033 dif ferential pressure; torque switch setting control increased.

• The number of events is greater than shown in Table 4 hecause more than one event was reported in a single LER, an additional search was made for the early months of 1978, or an LER referenced another LER.

o

- Table 7 ADDITIONAL INFORMATION CONCERNING E. I. HATCH 2 TOROUE SWITCH-RELATED EVENTS

• Event Date Proble.m and Correction System LER Number 1.

Valve 2P41-F315A failed to open, Service 06/24/79 torque switch had corroded to the water 79-057 switch shaft; torque switch repaired.

2.

Valve 2T49-F003A failed to open; Hydrogen 01/18/80 torque switch defective and replaced.

recombiner 80-004 3.

Valve 2E51-F008 failed to close; Reactor 05/06/80 torque switch defective and replaced.

core isol.80-055 cooling 4.

Valve 2E51-F008 failed to close:

Reactor 08/12/80 torque switch defective and replaced.

core isol.80-123 cooling 5.

Valve 2E41-F007A failed to close Residual 11/04/80 (failed leak rate test); torque switch heat 80-152 adjusted.

removal 6.

Valve 2E41-F049 failed leak rate High 11/04/80 test, torque switch adjusted.

pressure 80-152 coolant injection 4

i

)

1 i

• The number of events is greater than shown in Table 4 because more than one

~

event was reported in a single LER.

i m

1

o '

Table 8 ADDITIONAL INFORMATION CONCERNING DAVIS BESSE 1 TOROUE SWITCH-RELATED EVENTS

• Event Date Problem and Correction System LER Number 1.

Valve MS-603 would not open on the steam Main 08/29/77 generator drain; torque switch setting steam NP-33-77-72 increased frun 1. 5 to 3.0.

2.

Valve AF-3872 for AFP 1-2 would not open Auxiliary 10/25/77 due to high dif ferential pressure from feedwater 77-083 leaking check valve; torque switch defective and replaced.

3.

Valve AF-3870 for AFP l-1 would not open Auxiliary 03/16/78 due to high differential pressure from leaking feedwater 78-027 check valve and torqued out before opening; limit switch which bypasses the torque switch was adjusted.

4.

Valve AF-3869 for system 1-1 failed to Auxiliary 02/20/79 close; torque switch faulty and replaced feedwater 79-030 with heavier duty design.

5.

Valve DH-2735 failed to close because of Decay 03/20/79 boric acid buildup on stem; valve stem heat 79-041 cleaned, repacked and torque switch setting removal increased.

6.

Valve MS-106 torqued out on opening, Auxiliary 07/08/79 believed due to normal wear of valve feedwater 79-073 internals; torque switch setting increased but valve later failed to close and adjusted limit switch.

)

The number of events is greater than shown in Table 4 because an additional search was made for the early months of 1978 or an LER referenced another LER.

9 Table 9 ADDITIONAL INFORMATION CONCERNING COOK 2 TOROUE SWITCH-RELATED EVENTS i

Event Date Problem and Correction System LER Number 1.

Valve CM0-414 failed to operate Auxiliary 04/22/78 in prescribed time; torque switch cooling 78-027 contacts required burnishing and were out of adjustment.

2.

Valve IM0-220 failed to open; Emergency 12/17/79 torque switch was binding the operator core 79-051 mechanism.

cooling 3.

Valve VM0-102 failed _ to open; torque Containment 02/16/80-switch out of adjustment, air 80-010 purification

4 Table 10 ADDITIONAL INFORMATION CONCERNING OCONEE 3 TOROUE SWITCH-RELATED EVENTS Event Date Problem and Correction System LER Number 1.

Valve 3PR-9 failed to close; Containment 02/02/78 torque switch failed, replaced.

isolation 78-003 and new switch adjusted.

2.

Valve 3B5-3 failed to open; Containment 02/03/78 torque switch failed and was heat 78-004 replaced.

removal 3.

Valve 385-2 failed in an intermediate Containment 02/07/78 position with stem failed; caused or heat 78-005 aggravated by a faulty torque switch removal which was replaced.

.m

Table 11 DESCRIPTION OF TOR 0tlE SWITCH ADJilSTMENT-RELATED EVENTS AND CORRECTIVE ACTIONS FOR 1978-1980 L,

Plant (Docket Number),

Problem and Correction System Event Date and LER Number 1.

Valve MDV-94 would not Containment isolation Crystal River (302) close; torque switch adjusted system and control (RC 10/2/80 to higher value.

drain tank)80-041 2.

Valve CAV-3 would not close Containment isolation Crystal River (302)

(second and third events);

system and control 11/16/80 valve lubricated after (sample pressurizer 11/18/80 second event and torque waterspace)80-048 switch increased after third event.

3.

Valve CAV-3 would not close Containment isolation system Crystal River (302)

(fourth and fifth events);

and control (sample 12/8/80 valve lubricated after pressurizer water 12/9/80 fourth event and torque space)80-053 switch replaced after fifth event.

4.

HPI-LPI cross connect valve Emergency core Davis Besse (346) would not open, torque switch cooling 3/9/81 operated erratic with 81-017 torque out at less than setpoint torque; replaced torque switch.

5.

Valve SI-351A would not open, Emergency core Kewaunee (305) after manual assist it opened cooling 3/3/80 three times remotely but a work 80 015 request investigation found it stuck closed; torque switch adjusted up.

6.

HPSI valve HSI-M-54 failed Emergency core Maine Yankee (309) to operate as required, motor cooling 3/7/79 thermal overloads opened 79-006 because of improper torque switch setting; #.

7.

SCAT valve CS-M-66 failed Emergency core Maine Yankee (309) to operate as required, motor cooling 3/7/79 thermal overloads opened 79 006 because of improper torque switch setting; #.

1. Corrective action was not stated in the LER.

. Table 11 (continued)

Plant (Docket Number)

Problem and Correction System Event Date and LER Number 8.

Outboard isolation valve Reactor water Monticello (263) torqued out, current too high, cleanup 3/18/79 torque switch found adjusted 79-007 for maximum torque; #.

9.

Valve V-14-37 circuit breaker Isolation condenser Oyster Creek (219) tripped on closing with 9/14/78 isolation signal and failed to 78-017 open when signal removed, set screw on torque switch loosened and went to maximum torque; #.

10.

Valve M0-1-1001-36B tripped Low pressure Ouad Cities 1 (254) on thermal overload, thermal coolant injection 4/10/80 overload reset three times80-009 (valve failed three times); torque switch setting reduced.

11. Valve M0-2-1001-29A failed Low pressure Quad Cities 2 (265) to open; adjusted bypass of coolant injection 10/10/80 torque switch for more time 80-023 for disc to lift off the valve seat.

12. Valve ICV 66 failed closed Emergency core Salem 1 (272) and opened manually, motor cooling 10/22/80 and operator failed;80-058 operator replaced from stock and motor sent out for repair.

13.

Valve 1-FCV-62-136 Emergency core Sequoyah 1 (327) charging pump suction cooling 6/26/80 from RWST would not open; 80-141-torque spring was adjusted to stop the motor.

14.

Valve FCV-1-51 motor Auxiliary Sequoyah 1 (327) shorted, motor and operator feedwater 8/11/80 mismatched, motor rated 80-151 torque of 24 inch pounds and minimum operator setting of 28 inch pounds; #.

15.

Valve 2MOV-SW0002 failed Service water Zion 2 (304) to stroke to full open; 11/24/80 repaired operator and 80-030 control circuit.

~ '

Table !?

OESCRIPTION Di' LIMIT SWITCH-RELATED EVENTS AND CORRECTIVE ACTIONS FOR 1978-1980 Occurrence and Corrective Plant Unit, LER Number Action System ani Event Dat,e, 1.

EFW flow control valve i

. Cooling system Arkansas 2 failed to fully close; for reactor 78-068/03L-0 1in f t :stop switch was

.j auxiliaries and 8/12/78 realigned.

controls

~

2.

RHR injection 'talve 74-67 Containment Browns Ferry 1 failed to close upon isolation system 60-0?:i/03L-0 isolation, signal ; limit and controls 3/13/80 switch contact was cleaned and adjusted.

t 3.

HPCI steamline flow Containmarit Brunswick 1 isolation valve (E41J003).

isolatien system 78-041/03L-0' failed to close; limit and controls 4/10/78 switch contact cleaned.

4.

HPCI inboard steam supply Emergency Brunswick 2 isolation valve (E41-F002)

' core cooling system 78-002/03L closing time was 50.8 seconds, and controls

.1/4/ 78 -

tech spec limit is 50 seconds; i

valve open limit switch was adj usted.

y S.

CAC-V5 containment inerting s

Containmenth Brunswick 2 4

inlet valve would not open; isolation system 79-087/G3L-0

' actuator limit travel stops and controls' 10/29/79" asre correctly adjusted.

6.

' Isolation time for containme@

Containment Calvert dif ffs I normal sump isolation valve-isolation system 78-030/03L-0 (MOV-5463) was 15.5 seconds, and controfs.

6/7/18 tech spec limit 13.0 seconds; open limit switch was adjusted.

7.

CFT sample isolation valve Containment CrystalRiverb would not close; contact.

~ isolation system 80-033/03L-0 rotor number 2 was replaced.

and controls 8/3/80 l

RWCUsystemisolationvalYe' Reactor cooiant Ouane Arnold 8.

(M0V-2740) closed in 10.4 cleanup system '

80-047/03L-0 s

seconds, tech spec ifrrit i

1 and controls 4/11/80 i

10 seconds; 1imit switch adjust 6d.

v 9

1 t

1 g.

-rc_

3

Table 12 (continued)

Occurrence and Corrective Plant Unit, LER Nunber Action

_ System and Event Date 9.

Off-gas system auto

' Gas radioactive E. I. Hatch 1 isolation valve (IN62-F527) waste management 79-099/03L-0 failed in closed position; systems 12/6/79 limit switch adjusted.

10.

Primary containment isolation Containment Fitzpatrick 1 valve (27-MOV-ll3) required isolation system 79-016/03L-0 5.7 seconds to reach fully and controls 3/20/79 closed position, tech spec linit 5 seconds; open limit switch was adjusted.

11. RHR system discharge valve Containment Fitzpatrick 1 (10-M0V-67) would not open isolation system 80-035/03L-0 in response to an open signal:

and controls 4/15/80 open torque (switch) bypass limit switch was adjusted.

12.

Valve V6-120 in the north Station service H. R. Robinson 2 service water loop header water system and 78-020/03L-0 failed to open; limit switch controls R/25/78 was replaced.

13. RWST supply to charging pump Emergency Farley 1 suction valve (1-CVC-MOV-ll5D) core cooling 80-063/03L-0 would not open; MOV close limit system and controls 10/20/80 i

switch contact number 4 adjusted.

14. RHR isolation valve (MOV-1701)

Residual' North Anna 1 failed to close; limit switch heat removal 79-051/03L-0 contact adjusted.

system and controls 4/16/79

15. Feedwater flush valve (M03-2 Containment Peach Rottom 3

(

38A) failed to close; limit isolation system 80-014/03X-1 switch cleaned and adjusted and controls 6/8/80 j

16. RHRS containment cooling valve Residual Quad Cities 2 (M0-2-1001-34A) would only heat removal 80-024/03L-0 open far enough to give dual system and controls 10/10/80 l

position indication; limit switches adjusted.

17. Containment sump valve (FCV-Other Sequoyah 1 72-20) to Train 8 of engineered safety

'80-081/03L-0 l

containment spray would not features and their 5/27/80 j

open due to inoperable control s i

permissive f rom FCV-72-21 ;

limit switches associated with FCV-72-21 was adjusted I

e

' Table 12 (continued)

Occurrence and Corrective Plant Unit, LER Number Action System and Event Date 18.

FCV-72-20 containment sump Containment Sequoyah 1 valve to containment spray heat removal 80-189/03L-0 pump failed to open due to system and controls 11/19/80 inoperable permissive from FCV-72-21; limit switches associated with FCV-72-21 cleaned.

19.

Service water MOV to AFW Other engineered Zion 1 pump backup supply failed to safety features and 80-018/03L-0 stroke properly; limit switch their controls 4/2/80 adjusted.

20.

BIT outlet valve (2MOV-S18801A)

Emergency core Zion 2 was not fully closed; limit cooling system and 79-053/03L-0 switch adjusted.

control s 10/9/79 21.

DHR outlet valve ILP-14 Emergency core Oconee 1 failed to open; valve position cooling system 80-006/03L-0 limit switch which bypasses and controls 3/6/80 torque switch adjusted.

22.

Valve 2E51-F013 would not Reactor Brunswick 2 open fully; bypass wiring core isolation 80-067 around torque switch had not cooling system 9/23/80 been installed as designed; and controls wiring corrected.

23.

Valve RHR-MOV-25R would not Residual heat Cooper open remotely, torque switch removal system and 80-050 setting was decreased and controls 12/16/80 bypass wiring around the torque switch had not been installed on RHR-M0-25Af,8; wiring correcte'd.

24.

Valve FW-779 did not fully Main feedwater Davis Besse close even though control room 78-033 green light indicated close; 3/25/78 manually closed valve and adjusted number two rotor contact.

Table 13 DESCRIPTION OF MOTOR HilRN0lli EVENTS AND CORRECTIVE ACTIONS FOR 1978-1980 Plant Unit, LER No.

Occurrence and Corrective Action System and Event Date 1.

Motor for valve MOV-SI-869A Reactivity Control Beaver Valley 1 hurned up, line starter had System 80-011 failed; operator replaced.

2/26/80 2.

Motor failure on valve FCV-Reactor core Browns Ferry 1 71-31, cause unknown; motor isolation cooling 79-021 replaced.

9/2/79 3.

Grounded motor on torus Residual heat Browns Ferry I return valve FCV-74-71 removal 80-072 caused breaker to trip; motor 9/24/80 replaced.

4.

Motor for valve E51-F010 Reactor core Brunswick I found inoperable with insulation isolation cooling 78-059 damage; motor replaced and a 5/27/78 space heater was installed.

5.

Motor found burned up on Reactor core Brunswick I valve IE 51-045; af ter first isolation cooling 79-032 repair found brush shunt shorted 5/14/79 to case, repaired a second time and reinstalled.

6.

Motor failed on valve Ell-F008 Residual heat Brunswick 2 when excessive current was drawn removal 78-036 because electronechanical brake 4/3/78 failed; motor repaired and reinstalled, mechanical brake system removed.

7.

Motor burned up on valve F001 due High pressure Brunswick 2 to binding caused by pinion gear coolant injection 74-053 installed backward; damaged parts 7/21/79 replaced.

8.

Motor burned on valve E41-F006, High pressure Hatch I blackened condition of motor coolant injection 79-004 internals obscured any evidence 1/14/79 of cause; repaired motor and checked for mechanical obstruction.

9.

Valve IB21-F016 failed in mid.

Main steam Hatch I position due to failed motor winding 80-004 believed to be caused by moisture from 1/6/80 a valve directly above this-valve; motor replaced.

\\

.- Table 13 (continued)

Plant Unit, LER No.

Occurrence and Corrective Action System and Event Date 10.

Valve IE11-F015A failed to Residual heat Hatch 1 open, motor windings and rotor removal 80 095 severely burned; motor replaced.

8/8/80 11.

Valve, 2E41-F001, failed to open High pressure Hatch 2 during quick start, motor shunt coolant injection 78-056 field insulation degradation by 10/27/78 heat and valve stem was rough; motor rewound and stem replaced.

12.

Valve PE41-F041 failed to open High pressure Hatch 2 in specified time of 60 seconds, coolant injection 79-050 motor winding overheated and burned-6/9/79 due to loose connection in shunt field; motor replaced.

l' Breaker tripped during quick start High pressure Hatch 2 of valve 2E41-F001 due to motor coolant injection 79-067 failure, motor has a five minute 7/7/79 duty rating and was operated 12 times in a five-hour period; motor reworked, bench tested, and reinstalled.

14.

Valve 2E41-F041 failed to close High pressure Hatch 2 due to burned motor, pinion key coolant injection 79-086 had slipped out of position; new 7/30/79 motor installed, key replaced and locked.

15. Valve 2Et.1-F041 failed to open High pressure Hatch 2 due to burned motor, cause unknown coolant injection 79-118 but moisture or high humidity suspected:

11/3/79 design package change for continuous current saturation of winding.

16.

Valve 23-MOV-57 would not operate High pressure Fitzpatrick i due to burned motor: replaced motor.

coolant injection 78-060 8/6/78 I

17. Reactor recirculation system valve Reactor Monticello 1 motor failed; motor replaced.

recirculation 80-020 4/27/80

18. Outhoard HPCI steam supply valve High pressure Monticello 1 failed due to breakdown of motor coolant injection 80-025 winding insulation; installed new 7/29/80 motor.

19.

Inboard isolation valve failed to Reactor core Pilgrim 1 close due to burned motor and seized isolation cooling 80-047 contactor; motor and contactor replaced.

8/1/80

..._