ML20210U960

Forwards Response to IE Bulletin 85-003, Motor-Operated Valve Common Mode Failures During Plant Transients Due to Improper Switch Settings. Mod Will Be Fully Completed During 1987 Refueling Outage

ML20210U960
Person / Time
Site:	Monticello
Issue date:	10/01/1986
From:	Larson C NORTHERN STATES POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-85-003, IEB-85-3, NUDOCS 8610100398
Download: ML20210U960 (9)

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hMb Northem States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401 Telephone (612) 330-5500 October 1, 1986 Mr J G Keppler Regional Administrator - Region III U S Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Response to IE Bulletin 85-03 Attached please find information required by IE Bulletin 85-03, " Motor Operated Valve Common Mode Failures During Plant Transients Due to Improper Switch Settings."

Please contact us if you have any questions related to our program for completing th ction required by this Bulletin.

GE C E Lcrso Vice President Nuclear Generation CEL/EFE/ dab c: NRR Project Manager, NRC Resident Inspector, NRC Document Control Desk, NRC G Charnoff 8610100398 861001 PDR ADOCK 05000263 G PDR gg 5 - ll OCT 3 1986

UNITED STATES NUCLEAR REGULATORY COMMISSION NORTHERN STATES POWER COMPANY MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 RESPONSE TO IE BULLETIN 85-03 Northern States Power Company, a Minnesota corporation, by this letter dated October 1, 1986 hereby submits information required by IE Bulletin 85-03 for the Monticello Nuclear Generating Plant.

This letter contains no restricted or other defense information.

NORTHERN STATES POWER COMPANY By -

j CEL son Vice Pre nt, Nuclear Generation On this /d day of [ M , /9cfd before me a notary public in and for said County, personally appeared C E Larson, Vice President, Nuclear Generation, and being first duly sworn acknowledged that he is authorized to execute this document on behalf of Northern States Power Company, that he knows the contents thereof and that to the best of his knowledge, information and belief, the state-l ments made in it are true and that it is not interposed for delay.

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In accordance with IE Bulletin 85-03 entitled " Motor Operated Valve Common Mode Failures During Plant Transients Due to Improper Switch Settings",

item a, the design basis for the operation of motor operated valves in the the High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling Systems (RCIC) has been reviewed and documented. Table 1 attached contains documentation of the maximum expected differential pressures for both the opening and closing of each valve listed for all events to the extent that these valve operations and events are included in the Monticello plant existing, approved design basis. Motor operated valves for which no safety actions exist were also reviewed. Corresponding test differential pressures are documented in the attached Table-1 Supplement.

A program and schedule for bulletin compliance is contained in Attachment A.

Northern States Power Company has participated with the BWR Cwners' Group (BWROG) to conduct a design basis review for the operation of each valve.

The resulting General Electric report number NEDC-31322 entitled "BWR Owners' Group Report on the Operational Design Basis of Selected Safety-Related Motor-Operated Valves", dated September 1986, contains the systems description, the basis, and the assumptions for differential pressure calculation (refer to transmittal letter, T.A. Pickens to J.M.

Taylor, dated September 2, 1986). Calculations made in determining maximum expected differential pressures are consistent with the BWROG report with the following exceptions:

a) MO-2106 (RCIC Injection Valve Test Valve) is a normally shut valve and a safety action therefore exists to open this valve, b) MO-2096 (RCIC Turbine Accessory Cooling Water Valve), upon receipt of a turbine trip signal, simultaneously receives an automatic valve closure signal. The BWROG report equation has been modified accordingly.

For all but four valves listed in Table-1, the original plant design differential pressures exceed th; maximum expected differential pressures.

A preliminary verification through *he valve and actuator manufacturers indicates that these four actuators ere fully capable of delivering the torques required and at the corresponding valves are able to withstand s the additional thrustt.

The Monticello Plant complianco program, including the submittal of the final report, will be completed within 90 days following the conclusion of the plant's 1987 refueling outage. The tentative outage commencement date is October 14, 1987. Based on this schedule, the Monticello program will exceed the completion date specified in Item (e) of the bulletin by approximately four months.

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TABLE 1 VALVE IDENTIFICATION AND DIFFERENTIAL PRESSURES Valve Valve Valve IEB 83-03 Eval. Original

• Status of Control Syrtem Designation Description Safety Action D/P (Max.) Design D/P Circuit Modification HPCI MO-2034 Steam Line Isolation Valve (Inner) Valve Closing 1120 psi 1356 psi 1 HPCI MO-2035 Steam Line Isolation Valve (Outer) Valve Closing 1120 psi 1356 psi 1 HPCI MO-2036 Steam Admission valve Valve Opening 1120 psi 1356 psi 1 HPCI MO-2061 Suppression Pool Suction Isol. Valve Valve Opening 97 psi 70 psi 1 (Inner) Valve Closing 31 psi 70 psi 1 HPCI MO-2062 Suppression Pool Suction.Isol. Valve Valvo Opening 97 psi 70 pci 1 (Outer) Valve Closing 31 psi 70 psi 1 HPCI MO-2063 CST Suction Valve Valve Closing 23 psi 70 psi 1 HPCI MO-2068 Injection valve Valve Opening 1143 psi 1650 psi 1 RCIC MO-2075 Steam Line Isolation Valve (Inner) Valve Closing 1120 psi 1356 psi 1 RCIC MO-2076 Steam Line Isolation Valve (Outer) Valve Closing 3120 psi 1375 psi 1 RCIC MO-2078 Steam. Admission Valve Valve Opening 1120 psi 1356 psi 1 Valve Closing 1120 psi 1356 psi 2 RCIC MO-2096 Turbine Accessory Cooling Water V'lve a Valve Opening 1302 psi 1650 psi 1 Valve Closing 1302 psi 1650 psi 2 RCIC MO-2100 Suppression Pool Suction Isol. Valve Valve Opening 97 psi 82 psi. 1 (Inner) Valve Closing 31 psi 82 psi 3 RCIC MO-2101 Suppression Pool Suction Isol Valve Valve Opening 97 psi P2 psi 1 (Outer) Valve Closing 31 psi 82 psi 3

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TABLE 1 (cont)

VALVE IDENTIFICATION AND DIFFERENTIAL PRESSURES Valve Valve Valve IEB 85-03 Eval. Origindl

• Status of Control System Designation Description Safety Action D/P (Max.) Design D/P Circuit Modificatiori RCIC MO-2102 CST Suction Valve , Valve Closing 29 psi 82 psi 1 RCIC MO-2106 Injection Valve Test Valve Valve Opening 1292 psi 1650 psi 1 RCIC MO-2107 Injection Valve . Valve Opening 1218 psi 1650 psi 1 L

RCIC MO-2080 Trip and Throttle Valve ' valve Closing (Closure is by spring actutation.)

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TABLE 1 (Supplement)

VALVE IDENTIFICATION AND DIFFERENTIAL PRESSURES Valve Valve Valve IEB 85-03 D/P Original

• Status of Control System Designation Description Test Action Max. Test Pres. Design D/P Circuit Modification HPCI MO-2067 Injection Valve Test Valve Valve Opening 19 psi 1650 psi 4 Valve Closing 19 psi 1650 psi 4 HPCI MO-2071 CST Test Return Valve Valve Opening 19 psi 1650 psi 4 Valve Closing 19 psi 1650 psi 4 RCIC MO-3502 CST Test Return Valve Valve Opening 1053 psi 1650 psi 4 Valve Closing 16 psi 1650 psi 4

• Control Circuit Modification Status Code

1. Control Circuit Modification completed.

2. Control Circuit Modification scheduled for completion during the 1987 refueling outage.

3. Safety action requires remote manual operation.

Control Circuit Modification is not applicable.

4. No safety actipn exists. Control Circuit modification not required.

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fN Attachment A IEB 85-03 Motor Operated Valve Compliance Program and Schedule

1. For valves having safety actions, as listed in Table-1, a control circuit modification will be completed. This design modification will have the following features a) Bypass the torque switch during the valve's safety actuation. This eliminates the functions of the torque switch and torque switch bypass switches. (The torque switch is utilized only during valve sc.ating. )

b) ' Maintain torque switch effectiveness throughout the valve stroke during manual (non-safety action related) control switch actuations. 1 c) Allow for controlled valve seating during safety action actuation through the use of the torque switch.

d) Ensure the valve's seal-in and other operating characteristics are left unaffected.

The intent of this modification is to minimize valve and operator damage during routine evolutions while assuring maximum operability during valve safety action actuations.

The control circuit modification will be effective for valve safety action openings and closings for all events to the extent that these valve operations and events are included in the existing, approved design basis, with the exception of two valve safety action closures requiring remote manual actuation. Table-1 specifies the current status of the modification.

The modification will be fully completed during the 1987 Refueling Outage.

2. A review of actuator size and torque switch settings will be made to ensure sufficient valve stem thrust is developed under maximum expected differential prissure conditions. Total required stem thrust and stem torque will be calculated using either the actuator manufacturer's or the valve manufacturer's methodology, or equivalent. ,

To ensure full valve seating during valve closure under maximum expected differential pressure, torque switch settings will be obtained from Limitorque based on the calculated stem torque and torque switch / spring pack combination. During a safety action valve opening operation, the torque switch is fully bypassed. To ensure that the actuator is sufficiently sized to provide required stem thrust during this event, a comparison of required torque calculated to rated actuator torque will be made. Rated torque information will be provided from the actuator

• manufacturer. (Torque switch settings for remote manual valve openings will be obtained from Limitorque based on the calculated stem torque and torque switch / spring pack combination).

The review of actuator size and torque switch settings will be completed by June 1, 1987.

Attcchment A Paga 2 of 3

3. Existing methods for setting motor operated valve limit switches will be reviewed and the need for procedure revision will be determined. This is particularly important for setting the "open position" limit switch to prevent valve backseating.

With the modification described in item 1 completed, the " closed .

position" limit switch, during a valve safety action, functions only to:

a) provide valve position indication, b) set the time at which the torque switch is placed in the valve control circuitry during valve closure to regulate valve seating.

The " closed position" limit switch does not serve as a torque switch bypass switch during a safety action valve opening, and therefore is not a significant setting relative to valve safety action operations and events included in the plant's approved design basis.

Review of existing limit switch setting methods will be completed by June 1, 1987.

4. The methods used for selecting motor operator overloads at Monticello will be reviewed to ensure all overload requirements are met. The need for overload replacement will be determined.

This review will be completed by June 1, 1987

5. Procedures will be generated to change switch settings in cases where they are required as a result of the minimum stem thrust calculations or review of limit switch setting methods.

These procedures will be implemented during the 1987 Refueling Outage.

6. All valves listed in Table 1 will be stroke tested to verify that the settings established have been properly implemented. For those valves having a closing safety action, signature analysis testing (capable of indicating switch actuations, stem thrust, and actuator power) will be conducted to ensure each torque switch is cet correctly to provide adequate stem thrust for valve seating against maximum expected differential pressure. As a result of stroke and signature analysis testing, torque and limit switch settings may be changed to ensure valve operability. vslves which require switch changing due to testing will be retested.

During a " safety action opening" of the valve, the torque switch and torque switch bypass switch serve no function. Therefore, signature analysis testing of these switch settings during valve opening is not necessary.

This testing and switch readjustment will be completed during the 1987 Refueling Outage.

7. Operabi~ity of valves for which no safety function exists, will be demonstrated during the plant's monthly valve operability tests which will be conducted during plant start-up following the 1987 Refueling Outage.

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Attachment A Page 3 of 3

8. Existing plant maintenance procedures address the setting of actuator switches and inspections of the valve, the actuator, valve movement, wiring, and electrical connections. These procedures will be reviewed for adequacy and if necessary, revised to ensure that switch settings, as dete mined by this program, are maintained to allow proper valve opera. ion for the life of the plant.

The maintenance procedures will be revised within 90 days of the completion of the 1987 Refueling Outage.

9. A written report on the completion of Monticello's IE Bulletin 85-03 Motor Operated Valve Compliance Program will be provided to the NRC.

This report will contain the following:

a) A verification of completion of the compliance program.

b) A summary of the findings as to valve operability prior to any adjustments, c) A summary of data, containing as a minimum the data requested in the IE Bulletin 85-03 attached table entitled " Suggested Data Summary Format".

This report will be submitted within 90 days of the completion of the 1987 Refueling Outage.

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