ML20134M636

Forwards Draft Info Notice Re Incorrect Effective Diaphragm Area Values Used in Pneumatic Actuator Calculations on Plant Units 1 & 2 for Technical Review.Comments Requested by 961125

ML20134M636
Person / Time
Site:	LaSalle
Issue date:	11/21/1996
From:	Chaffee A NRC (Affiliation Not Assigned)
To:	Matthew Smith COMMONWEALTH EDISON CO.
References
NUDOCS 9611250201
Download: ML20134M636 (5)

Text

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. . Myanber 21, 1996 Mr. Mark Smith LaSalle County Station Commonwealth Edison 2601 North 21st Road Marseilles, IL 61341

SUBJECT:

REQUEST FOR A TECHNICAL REVIEW 0F A DRAFT INFORMATION NOTICE ON INCORRECT EFFECTIVE DIAPHRAGM AREA VALUES USED IN PNEUMATIC ACTUATOR CALCULATIONS - LASALLE COUNTY STATION, UNITS 1 & 2

Dear Mr. Smith:

The U.S. Nuclear Regulatory Commission (NRC) is planning to issue an information notice on the potential failure of safety-related air-operated valves because of the use of incorrect pneumatic actuator effective diaphragm area values supplied in vendor literature. We ask that you review the ,

enclosed draft of that information notice to ensure the technical information i is accurate. Your cooperation in this matter is appreciated. Please return any comments you may have as soon as possible. A copy of this request and your response will be placed in the Public Document Room for review by the public. Your response should be mailed to:

U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation ATTN: David Skeen, PECB MAIL STOP: 011E4 Washington, DC 20555-0001 Please address any questions you may have on this matter to David Skeen of my  !

staff. Mr. Skeen may be reached by phone (301) 415-1174 or you may fax comments to (301) 415-2279. If no comments are received by close of business November 25, 1996, we will assume the technical information in the notice is correct.

Sincerely, kNeYE f e,. Chief Events Assessment and Generic Communications Branch Division of Reactor Project Management 9611250201 961121 PDR ADOCK 05000373 Office of Nuclear Reactor Regulation P PDR Docket Nos. 50-373 and 50-374 4

Enclosure:

Draft Information Notice

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6 LaSalle County Station Unit Nos. 1 and 2 cc:

Ms. I. Johnson LaSalle Station Manager.

Acting Manager, Nuclear Regulatory Services LaSalle County Station Commonwealth Edison Company Rural Route 1 Executive Towers West III P.O. Box 220 1400 Opus Place, Suite 500 Marseilles, Illinois 61341 Downers Grove, Illinois 60515 Robert Cushing Phillip P. Steptoe, Esquire Chief, Public Utilities Division Sidley and Austin Illinois Attorney General's Office One First National Plaza 100 West Randolph Street Chicago, Illinois 60603 Chicago, Illinois 60601 Assistant Attorney General Michael I. Miller, Esquire 100 West Randolph Street Sidley and Austin Suite 12 One First National Plaza Chicago, Illinois 60601 Chicago, Illinois 60603 U.S. Nuclear Regulatory Commission Document Control Desk-Licensing Resident Inspectors Office LaSalle Station Commonwealth Edison Company 2605 N. 21st Road 1400 Opus Place, Suite 400 Marseilles, Illinois 61341-9756 Downers Grove, Illinois 60515 Chairman LaSalle County Board of Supervisors LaSalle County Courthouse Ottawa, Illinois 61350 Attorney General 500 South Second Street Springfield, Illinois 62701 Chairman Illinois Commerce Commission Leland Building 527 East Capitol Avenue Springfield, Illinois 62706 Illinois Department of Nuclear Safety Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, Illinois 62704 Regional Administrator U.S. NRC, Region III 801 Warrenville Road Lisle, Illinois 60532-4351 0

UNITED STATES NUCLEAR REGULATORY COMMISSION l OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555-0001 November xx,1996 NRC INFORMATION NOTICE 96-XX: INCORRECT EFFECTIVE DIAPHRAGM AREA VALUES IN VENDOR MANUAL RESULT IN POTENTIAL FAILURE OF PNEUMATIC DIAPHRAGM ACTUATORS Addressees All holders of operating licenses or construction permits for nuclear power reactors.

Puroose The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert addressees to the fact that some vendors have published incorrect values for effective diaphragm area for some spring type pneumatic diaphragm actuators and that use of these incorrect values may result in safety-related air-operated valves not fully closing under design basis conditions, it is expected that recipients will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this information notice are not NRC requirements; therefore, no specific action or written response is required.

Descriotion of Circumstances On October 4,1996, Commonwealth Edison, licensee for the LaSalle County Station, issued a Part 21 notification pursuant to 10 CFR Part 21, Sections 21.1(b), 21.3a(3), and

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i 21.3d(4). The notification identified the defect as incorrect values for the effective ]

diaphragm areas, as published by the original and current valve vendors, for certain models

• of pneumatic actuators.

The original valve vendor, Black, Sivalls, and Bryson (BS&B), was later purchased by WKM Valve Division of ACF Industries, then by Muesco, and by Anchor / Darling Valve  !

Company. The affected model of actuator is the Model 70-13 pneumatic diaphragm l actuator, sizes 35,70,140, and 280. The size refers to the published diaphragm area in square inches. The affected actuators are either direct acting (spring to open or close, depending on the application) or reverse acting (normally spring to close) spring return actuators.

The Part 21 notification included an attachment providing a Nuclear Plant Reliability Data System (NPRDS) listing of valves of the applicable model number by plant; however, the listing may not include all of the applicable valves and may include valves that are not safety related or that are not required to isolate as are the primary containment isolation j i

1 i .. . ..

IN 96-XX L' November XX,1996 i

Page 2 of 3

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I valves at the LaSalle County Station. Some of the valves listed are not diaphragm j actuated valves and the identification of some items is incomplete. The present

, manufacturer, Anchor / Darling Valve Company, was unable to compile a complete listing of j the actuator' applications because purchase order records from the original vendor are g unavailable.

4

) Discussion The licensee found discrepancies in the bench set values of the actuators during the

, LaSalle County Station refueling outage that took place from February through April 1996.

The published bench set and the actual bench set values, indicated from testing by the

] plant mechanics, were inconsistent. " Bench set" refers to the amount of preload and final

j. compression force placed on the actuator spring so that the applied spring force on loss of i air will achieve the required travel of the valve stem. Bench set adjustments are made by

applying air pressure to the actuator in accordance with the manufacturer's published

values and adjusting the spring compressive force by means of an adjusting nut to achieve i the desired relationship between air pressure and valve stem travel. When performing

{ bench set testing, incomplete valve stroke is typically indicative of a stiffer-than-expected i spring. However, testing by the licensee indicated that the springs were within j manufacturer's tolerances and additional testing with a known spring force, a known air j supply pressure, and a known load indicated that the actual effective diaphragm area, i: which relates to the force opposing the spring as well as to the compression of the spring j for proper preloading, was less than the published values.

j Anchor / Darling Valve Company was contacted by the licensee and performed a series of l i tests to determine the actual effective diaphragm area. These tests indicated that the

! actual diaphragm areas of the various sizes of the Model 70-13 actuators were j approximately 90 percent of the published values. Further testing by the licensee j uncovered a contributing problem that further reduced the effective diaphragm area.

4 The diaphragm case consists of two halves bolted together. Generally one half is deeper

than the other. It was discovered that reverse-acting actuators assembled with a deep  ;

upper half caused unintended stretching of the diaphragm within the casing. l

(

The licensee determined that the primary containment isolation valves would have closed

l. at the design-basis-accident containment pressure of 40 pounds per square inch; however, j many of the valves may not have been properly set up to close against the normally higher

_ system pressure under other eccident conditions. That is, the valves may not have closed

under the highest expected differential pressure of the contained system fluid. Further i

j details of the concern are in Licensee Event Report 50 373/96-011, dated October 28,

! 1996 (Accession No. 9611010277). 3 l The licensee determined which valves at the LaSalle County Station were affected and was

! able to properly adjust the actuators to account for the discrepancies between the I

published values for the diaphragm area and the actual diaphragm area by (1) adjusting the i bench set on the spring to achieve full travel of the valve and (2) reversing the diaphragm

] casings so that the deeper part of the casing was installed on the bottom with the l shallower part of the casing installed on top to prevent the diaphragm from stretching.

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l IN 96-XX November XX,1996 Page 3 of 3 The licensee has not identified similar problems on actuators made by other manuf acturers, but licensees should be aware of the concern when testing and making adjustments to the bench set of pneumatic actuators. The proper setup of these actuators is especially important when the attached valve is used for isolation in a safety-related application.

Licensees may wish to review their valves and actuators for applicability of this information.  ;

1 This information notice requires no specific action or written response. If you have any questions about the information in this notice, please contact one of the technical contacts listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

l Thomas T. Martin, Director  ;

Division of Reactor Program Management l Office of Nuclear Reactor Regulation l

Technical contacts: Patricia Campbell, NRR j (301)415-1311 l E-mail: pic@nrc. gov David Skeen, NRR j (301) 415-1174 '

E-mail: dis @nrc. gov Andrew Dunlop, Rlli (630) 829-9726 E-mail: axd7@nrc. gov

Attachment:

List of Recently issued NRC Information Notices

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