ML20213G626

Forwards Motor-Operated Valves Refurbishment Program Status Summary, Per IE Bulletin 85-003, Motor-Operated Valve Common Mode Failures During Plant Transients Due to Improper Switch Settings

ML20213G626
Person / Time
Site:	Rancho Seco
Issue date:	11/05/1986
From:	Julie Ward SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Martin NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
IEB-85-003, IEB-85-3, JEW-86-667, NUDOCS 8611180235
Download: ML20213G626 (10)

Text

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SACRAMENTO MUNICIPAL UTILITY OtSTRICT G P. O. Box 15830, Sacramento CA 95852-1830 (9161 452 3211 AN ELECTRIC SYSTEM SERVING THE HEART OF CALIFORNIA JEW 86-667 November 5, 1986 U. S. Nuclear Regulatory Commission Region V Office of Inspection and Enforcement 1450 Maria Lane, suite 210 Walnut Creek, CA 94596 Docket 50-312 Rancho Seco Nuclear Generating Station Unit il PROGRAM STATUS

SUMMARY

, RESPONSE TO IE BULLETIN NO. 85-03; MOTOR OPERATED VALVE COMMON MODE FAILURES DURING PLANT TRANSIENTS DUE TO IMPROPER SWITCH SETTINGS

References:

Letter JEW 86-023, J. E. Ward (SMUD) to J. B. Martin (USNRC);

Response to IE Bulletin No. 85-03; Motor Operated Valve Common Mode Failures During Plant Transients Due to Improper Switch Settings, Dated May 16, 1986.

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Dear Mr. Martin:

The above referenced letter provided a description of the District's program to address IE Bulletin No. 85-03 action items, in accordance with the l requirements of Item e of the subject bulletin. In order to provide further assurance of the proper operability of other station motor operated valvea (MOVs), the District expanded the scope under the MOV Refurbishment Program to include (1) all safety related MOVs and (2) all other MOVs on-site.

Additionally, the program has been enhanced through the use of MOVATS, INC.

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response signature analysis equipment and computer based baseline comparison / analysis techniques, to cite two examples. All MOV Refurbishment Program work on the thirty IEB 85-03 MOVs and all other safety related MOVs will be completed prior to restart.

In order to keep you apprised of our progress, attached is a status summary of the District's MOV Refurbishment Program to comply with IEB 85-03. As you will note, the program summary is structured consistent with the specific action items required by the bulletin. For each element of the program, the

" Current Program in Progress" description includes the elements of the District's May 16, 1986 response and subsequent enhancements which result in a more comprehensive program, consistent with the District's commitment to excellence.,

Based on the scope and depth of the program that is being implemented, the District is confident that its actions will address the immediate issues regarding MOV operator switch settings. We feel that the MOV maintenance, configuration control and procedural revision / upgrade actions being taken as a result of this program, will ensure the minimization of future MOV related problems.

8611180235 861105 PDR ADOCK 05000312 G PDR DISTRICT HEADQUARTERS O 6201 S Street, Sacramento CA 95817-1899 -

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Status Update Summary November 5, 1986 Through the transmittal of this letter, the District requests that the NRC conduct a priority review of the attached program. Additionally, we request that approval of, and/or comments on, the program in progress be provided.

If you have any questions, please contact Jerry Delezenski of my staff at (209) 333-2935, extension 3909.

Sincerely,

/ /

Jo n . Ward uty General Manager, Nuclear Attachment cc: Sydney Miner, NRC, Bethesda Tony D'Angelo, NRC, Rancho Seco 1

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• MOV REFURBISHMENT PROGRAM STATUS

SUMMARY

A. DESIGN BASIS REQUIRED BY IEB 85-03:

Review and document the design basis for the operation of each valve.

This documentation should include the maximum differential pressure expected during both opening and closing the valve for both normal and abnormal events to the extent that these valve operations and events are included in the existing, approved design basis, (i.e., the design basis documented in pertinent licensee submittals such as FSAR analyses and fully-approved operating and emergency procedures, etc.). When determining the maximum differential pressure, those single equipment failures and inadvertent equipment operations (such as inadvertent valve closures or openings) that are within the plant design basis should be assumed.

REPORTED BY J. E. WARD LTR TO NRC, MAY 16, 86:

The District conducted a study (ERPT-E0181) on each of the Rancho Seco Updated Safety Analysis Report (USAR) Chapter 14 accidents to identify the motor-operated valves which are required to function in order to mitigate each event. The valves (30 applicable to IEB 85-03 criteria) and the maximum differential pressure associated with each valve have been identified and included in the Refurbishment Program.

CURRENT PROGRAM IN PROGRESS:

In addition to the thirty IEB 85-03 valves, the scope of the Refurbishment Program has been increased to include (1) all safety related Motor Operated Valves (MOVs) and (2) other MOV assemblies on site.

The maximum differential pressure (delta P) for each valve has been determined and recorded. These values are currently being verified and used in analytical thrust / torque calculations which will result in the determination of torque switch settings after the MOV refurbishment.

Calculations are being performed for each MOV to determine the minimum operator torque / thrust necessary to open and/or close the valve under maximum delta P conditions.

The maximum allowable load for each valve and each operator is being determined using the following process:

1. The valve manufacturer is contacted to obtain seat port information and other valve specific information.

2. Limitorque furnishes operator data to identify the "as shipped" operator gear ratio and confirm the aizing information furnished by the valve manufacturer.

3. Preliminary loads (normal and maximum), valve stem diameter,

stem thread pitch, stem thread lead, motor RPM and unit gett i

r ratio are developed, based on vendor information. The

' calculated thrust loads are a conservative summation of the valve stem thrust, the packing load and the stem load. The calculations assume minimum voltage and maximum delta P.

4. The following field information is confirmed prior to using the analytically determined preliminary loads:

a. Valve Stem Diameter

b. Stem Thread Pitch

c. Stem Thread Lead

d. Motor RPM and HP/ Torque

e. Operator Unit Gear Ratio

f. Verification of Spring Pack Number (if available)

g. Operator Serial Number

5. For final loads (normal and maximum), the valve vendors will furnish the following:

a. On safety related valves and other plant valves frequently required to operate, where valve serial numbers are available, the valve serial number will be identified and the valve vendor's specific information for operator sizing will be obtained (stem diameter, stem thread pitch, stem thread lead, seat port diameter, valve thrust, and required torque / thrust for the design maximum differential pressure).

b. On the remaining valves and where serial numbers are not available, the valve vendor will furnish seat port areas for the globe and gate valves from general design information. For the ball and butterfly valves, the supplier will furnish stem diameter and disc weight from general design information.

6. The valve and operator information is compared, any conflicts are resolved and the torque / thrust values for the MOV assemblies  ;

are provided.

7. MOVATS, INC. calculates design pressure stem thrust requirements for flow and pressure only, using MOVATS verified equations.

The calculated torque / thrust values are provided to the District.

The torque / thrust inputs are compared, discrepancies are resolved, and the data is entered into the on-site document control system for implementation.

B. SWITCH SETTINGS / DOCUMENTATION REQUIRED BY IEB 85-03:

Using the results from item a above, establish the correct switch settings. This shall include a program to review and revise, as

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necessary, the methods for selecting and setting all switches (i.e.,

torque, torque bypass, position limit, overload) for each valve operation (opening and closing).

If the licensee determines that a valve is inoperable, the licensee shall also make an appropriate justification for continued operation in accordance with the applicable technical specification.

PROPOSED BY J. E. WARD LTR TO NRC, MAY 16, 86:

Obtain current switch settings by manually moving the valve using the handwheel.

Record the torque switch setting and torque load on the handwheel.

Collect nameplate data from valve and operator.

Using the data collected, calculate and document the analytic load required to be placed on the stem for the most adverse operating conditions.

The most adverse analytic load will be compared to the current condition and compared with the allowable condition for the valve, with the allowable thrust and torque for the operator, and with the allowable motor usage torque to determine if the operator is properly sized.

The switch settings will be documented on controlled Engineering Drawings maintained under the configuration control system for the Rancho Seco Nuclear Generating Station.

Analytical determination of torque and thrust, using values supplied by valve vendors and motor-operator vendors, will be accomplished.

Use of the analytical methodology will establish a load and corresponding handwheel torque required to achieve the load.

Limit switch settings will be established as a standard percent open for the open torque switch bypass setting.

, Open limit switch settings will be adjusted to ensure that the valves are not backseated.

4 CURRENT PROGRAM IN PROGRESS:

! The "as-found" data on each IEB 85-03 MOV assembly is being recorded in

! the IED 85-03 Data Summary and on the on-site controlled documents. For each MOV within the Refurbishment Program, the Motor Operated Valve Data controlled site document (E-1012) is being revised to include data on the i

valve, the operator, the motor, the reference drawings / documents, and the l MOV dynamic responses (see attachment). Each of the electrical drawings i and mechanical drawings is being verified for as-built accuracy as each assembly is refurbished and tested.

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Specific mechanical maintenance procedures have been written and are in use in the refurbishment of the motor operators. Any known deficiencies on the valves or operators are being corrected prior to reassembly.

Internal challenges to assembly operability are being summarized in the IEB 85-03 Data Summary. The refurbishment includes examination of all components for continued service, replacement of all consumable items and initial setting of switches. Final settings are being performed during the electrical maintenance signature analysis baseline testing.

A review of the policy and existing procedures for switch setting has resulted in an electrical procedure rewrite and a clarification of logic for MOVs. The acquisition of dynamic testing equipment (MOVATS) and software allows precision switch setting, functional confirmation, and the establishment of a baseline data base.

On a case-by-case basis, the following items were reviewed:

a. Open/Close Torque Switch Bypass Limit Switches (IEN 186-29)

b. Open/Close Limit Switches (IEN 986-71)

c. Open/Close Torque Gwitches (IEN #84-10 and IEC #77-01)

d. Switch Control for Butterfly and Three-Way Valves

e. Overload Devices

f. Interlocks with Other Equipment (IEN 886-29) 9 Position Indications (IEN 886-29)

h. Operator Heaters (IEN 886-71 and IEB #79-01B)

1. Termination Splicing (IEN 886-53)

j. Environmental Qualification (EQ) (IEN 086-03)

k. Lubricant (IEN 979-03)

1. Pinion Gear Installation (IEN 085-22)

m. Gearhead Worm Gear Orientation (IEN #83-02)

n. Stem Nut Lock Nut Staking (IEC #79-04)

o. Hammering Effect from Non-Locking Gear Set (IEN 985-20)

Each item was addressed, abnormalities resolved, and specific direction given in procedures and recorded in controlled documents.

C. TESTING / RECORDING / ANALYSIS REQUIRED BY IEB 85-03:

Individual valve settings shall be changed, as appropriate, to those established in item b, above. Whether the valve setting is changed or not, the valve will be demonstrated to be operable by testing the valve at the maximum differential pressure determined in item a above with the exception that testing motor-operated valves under conditions simulating a break in the line containing the valve is not required. Otherwise, justification should be provided for any cases where testing with the maximum differential pressure cannot practicably be performed. This justification should include the alternative to maximum differential I

pressure testing which will be used to verify the correct settings.

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Note: This bulletin is not intended to establish a requirement for valve testing for the condition simulating a break in the line containing the valve. However, to the extent that such valve operation is relied upon in the design basis, a break in the line containing the valve should be considered in the analyses prescribed in items a and b above. The resulting switch settings for pipe break conditions should be verified, to the extent practical, by the same methods that would be used to verify other settings (if any) that are not tested at the maximum differential pressure.

Each valve shall be stroke tested, to the extent practical, to verify that the settings defined in item b above have been properly implemented even if testing with differential pressure can not be performed.

PROPOSED BY J. E. WARD LTR TO NRC, MAY 16, 86:

Each operator will be mechanically and electrically refurbished to ensure proper working condition.

Following refurbishment, the torque and limit switch settings will be made on the operator. The torque switch settings will be input through the actuator handwheel and set to a specific value of handwheel torque.

The open torque switch bypass switch will be set to a fixed percentage of disc motion.

The open limit switch will be set to ensure valves are not backseated.

Three way valves will be set to torque out in each direction.

The handwheel torque values and corresponding torque switch settings will be recorded along with the limit switch settings.

Once the operators have been refurbished and new switches set, the valves will receive a delta P test.

Analytical justification will be provided for those that do not receive a delta P test.

The test program will record as appropriate, valve stroke time, confirmation of switch operation, inlet and outlet pressures, flow and system alignment.

CURRENT PROGRAM IN PROGRESS:

Each of the MOV assemblies is being mechanically and electrically refurbished and deficiencies are being recorded and corrected. Specific mechanical procedures direct the work activities from removal, inspection, and reassembly through coarse limit switch setting by turn-of-the handwheel methods. A specific electrical procedure directs the fine tuning of the switch settings, baseline dynamic response signature gathering and motor-load threshold acquisition. The correct dynamic response is being ensured with MOVATS Series 2150 systems. A MOVATS field representative is consulting with District EM personnel who have been

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formally trained in the use of the system and in response signature analysis. Valve work and baseline data gathering are done with the system dry and de-pressurized. The "as-left" response data will be added to the controlled documents by a revision for future reference.

In conjunction with the system testing, each IEB 85-03 MOV assembly will be tested, where practical, consistent with the IEB 85-03 Item c requirements. Selected valves will be tested to demonstrate that the MOV assembly is operable at the maximum differential pressure with minimum supply voltage. The MOVATS signatures at identified differential pressures will first be recorded onto bubble memory storage, then transferred to the specific MOV computer diskette for analysis and comparison to (1) the MOV's unpressurized dynamic response signatures and (2) the industry full or partial pressure test data available from MOVATS, INC. The test results will allow the completion of the IEB 85-03 Data Summary and a detailed record of MOV assembly response to worst case conditions. Those MOV assemblies which fail to function properly during system testing will be declared inoperable and the replacement units will be subject to the above mentioned MOV program requirements. This will ensure that full operability is demonstrated for all MOVs onsite.

The hard copy controlled documents and the computer stored response signature records will provide the baseline for future comparisons of dynamic MOV assembly response. In accordance with procedural work planning, each future work activity affecting the response of the MOV assembly will include a MOVATS measurement and comparison requirement (threshold value or complete signature acquisition).

D. PROGRAMMATIC SOLUTIONS REQUIRED BY IEB 85-03:

Prepare or revise procedures to ensure that correct switch settings are determined and maintained throughout the life of the plant. Ensure that applicable industry recommendations are considered in the preparation of these procedures.

PROPOSED BY J. E. WARD LTR TO NRC, MAY 16, 86:

Generic compliance with action required by IEB 85-03.

CURRENT PROGRAM IN PROGRESS:

Correct switch settings will be maintained for all MOV assemblies on-site by the continued use of several new procedures. New mechanical maintenance procedures have been issued and are in use for refurbishing the motor operators. These procedures direct the detailed examination of all components for continued service, replacement of consumable items and initial setting of switches.

A new electrical maintenance procedure has been issued and is in use for detailing the testing of MOVs using MOVATS dynamic response systems. This procedure specifically directs the setting of switches to those values

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recorded on the controlled documents, thus ensuring continued performance within the design basis. Also included within this procedure are the directions for the following signature acquisitions:

a. Motor Load Threshold

b. Thrust Measuring Device (TMD) and Control Switch

c. Motor Current

d. Motor Load These response signatures are transferred to computer diskettes for storage and future use in comparisons and analyses.

Preventative maintenance (PM) tasks are being written for each MOV assembly on site. Environmental Qualification (EQ) considerations establish a task interval on most MOV assemblies with individual assessments establishing the interval on the remaining units. Once detailed and entered into the existing PM Program, the tasks will be scheduled for work and the results included in the machinery history for each assembly. The minimum confirmation of operability will be the comparison to the MOVATS baseline motor load threshold value. Any discrepancies identified during the PM task could lead to additional MOVATS signatures and analyses for resolution. Each PM task includes all the items proposed in the MOVATS, INC. Performance and Monitoring Program presented to the NRC in September 1986.

E. SCHEDULE The following is an updated status of the MOV Refurbishment Program tasks:

1. Determination of Differential Pressures Completed

2. Submittal of Projected Program Completed

3. Training of Personnel Completed

4. Preparation of Procedures Completed

a. EM.ll7A

b. M.115

c. M.ll6

5. Calculation Data Collection

a. Valve manufacturer input Commenced 8/4/86

b. Operator manufacturer input Commenced 8/4/86

6. Analytical Calculation Commenced 9/15/86

7. Refurbish Operators and valves Commenced 9/2/86

8. Field Data Confirmation Commenced 9/2/86

9. Torqua/ Thrust Values Determined Commenced 9/15/86

10. MOVATS, INC. Provides Torque / Thrust Values Commenced 10/1/86

11. Preparation of On-Site Documents Commenced 10/14/86

12. Switch Settings Commencing 10/26/86

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A I B I C .,

VALVE INFORMATION OPER ATOR INFORMATION MOTOR INFORMATION g VALVE EOuiPMENT L D. OPERATOR MANUFACTURER - MOTOR MANUFACTURER ,

sERveCE TYPE S size sERi Ai NUMBER 2

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$ AN51 RATING UNIT PULL 0uf EFFICIENCY NPM (NAMEPt ATE) 6 PURCHAst ORMR MAN 0*MEEL GEAR RATIO MOTOR APPLICATION FAC M UNIT GEAR Raft 0 DUTY HATING -

SERIAL NUMBER 7 des GN SPEED OF OPER ATION $EC INSUL AflON CL ASS g $ TEM TYPE Liuti SwlTCH TYPE (2 0R 4 ROTOR 1REv0LVING / MON REVOLVING) AND MATERIALI 9 DRECTaON OF Flow MIN. REO'D. SETTING THRUST gg MOTOR DESIGN TOROUE FT-L85 (OVER / UNDER $E AT) ($EE NOTE 63 MOTOR MANIMdM TOROUE FT-L S$

STEM DIAMETER ,,- WIN. REO'O. SETTING TOROUE 10 AT PACniNG tsEE NOTE &l FT-LDS STEM DIAMETER MAJOR iN. DE5iGN TMRUST AT AP M NOR L85 REFERENCE DWGS. / DOCUMENTS AT THRE ADS iN .

g THRE AD PITCH

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