ML20134M658
| ML20134M658 | |
| Person / Time | |
|---|---|
| Issue date: | 11/21/1996 |
| From: | Chaffee A NRC (Affiliation Not Assigned) |
| To: | Knecht W ANCHOR/DARLING VALVE CO. |
| References | |
| NUDOCS 9611250221 | |
| Download: ML20134M658 (4) | |
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Movater 21, 1996 Ja Anchor / Darling' Valve Company i
1 ATTN: William Knecht 701 First Street P. O. Box 3428 Williamsport, PA 61341
SUBJECT:
REQUEST FOR A TECHNICAL REVIEW.0F A DRAFT INFORMATION NOTICE ON INCORRECT EFFECTIVE DIAPHRAGM AREA VALUES USED IN PNEUMATIC ACTUATOR CALCULATIONS
Dear Mr. Knecht:
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 j
enclosed draft of that information notice to ensure the technical information 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 1
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, kN f.Wa ee, Chief Events Assessment and Generic Communications Branch i
Division of Reactor Project Management i
Office of Nuclear Reactor Regulation
Enclosure:
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NUCLEAR REGULATORY COMMISSION j
OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555-0001 4
1 November xx,1996 L
NRC INFORMATION NOTICE 96-XX: INCORRECT EFFECTIVE DIAPHRAGM AREA VALUES i
IN VENDOR MANUAL RESULT IN POTENTIAL FAILURE OF PNEUMATIC DIAPHRAGM l
ACTUATORS f
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 j
. incorrect values may result in safety-related air-operated valves not fully closing under j'
design basis' conditions. It is expected that recipients will review the information for-j-
applicability to their facilities and consider actions, as appropriate, to avoid similar i
problems. However, suggestions contained in this information notice are not NRC.
requirements; therefore, no specific action or written response is required.
Descriotion of Circumstances
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On October 4,1996, Commonwealth Edison, licensee for the LaSalle County Station, r
issued a Part 21 notification pursuant to 10 CFR Part 21, Sections 21.1(b), 21.3a(3), and 21.3d(4). The notification identified the defect as incorrect values for the effective i
diaphragm areas, as published by the original and current valve vendors, for certain models of pneumatic actuators.
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The original valve vendor, Black, Sivalls, and Bryson (BS&B), 'as later purchased by
-WKM Valve Division of ACF industries, then by Muesco,'an by Anchor / Darling Valve Company. The affected model of actuator is the Model 70-13 pneumatic diaphragm i
actuator, sizes 35,70,140, and 280. The ' size refers to the published diaphragm area in l
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 2
actuators.
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The Part 21 notification included an attachment providing a Nuclear Plant Reliability Data j
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 2
f.'
safety related or that are not required to isolate as are the primary containment isolation j:
i k
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,4-IN 96-XX i
November XX,1996
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Page 2 of 3 valves at the LaSalle County. Station. The present manufacturer, Anchor / Darling Valve Company, was unable to compile a complete listing of the actuator applications because i
purchase order records from the original vendor are unavailable.
l Discussion 1
i The licensee found discrepancies in the bench set values of the actuators during the l
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 3
compression force placed on the actuator spring so that the applied spring force on loss of air will achieve the required travel of the valve stem. Bench set adjustments are made by
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applying air pressure to'the actuator in accordance with the manufacturer's published
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values and adjusting the spring compressive force by means of an adjusting nut to achieve 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 spring. However, testing by the licensee indicated that the springs were within manufacturer's tolerances and additional testing with a known spring force, a known air supply pressure, and a known load indicated that the actual effective diaphragm' area, which relates to the force opposing the spring as well as to the compression of the spring for proper preloading, was less than the published values.
Anchor / Darling Valve _ Company was contacted by the licensee and performed a series of 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 approximately 90 percent of the published values. Further testing by the licensee uncovered a contributing problem that further reduced the effective diaphragm area.
Dimensions of the diaphragm casing, which consists of two halves bolted together, dimensions did not comport with the dimensions in the vendor drawings in that the upper casing was deeper than the lower casing, unintendedly stretching the diaphragm within the casing.
The licensee' determined that the primary containment isolaton valves would have closed at the design-basis accident containment pressure of 40 pounds per square inch; however,
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many of the valves may not have been properly set up to close against.the normally higher system pressure under other accident conditions. That is, the valves may not have closed I
under the highest expected differential pressure of the contained system fluid. Further details of the concern are in Licensee Event Report 50-373/96-011,. dated October 28, 1996 (Accession No. 9611010277).
The licensee determined which valves at the LaSalle County Station were affected and was able to pronerly adjust the actuators to account for the discrepancies between the j
published values for the diaphragm area and the actual diaphragm area by (1) adjusting the 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 shallower part of the casing installed on top to prevent the diaphragm from stretching.
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4 IN 96 XX f
November XX,1996 Page 3 of 3 The licensee has not identified similar problems on actuators made by other manufacturers, 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.
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.
Thomas T. Martin, Director Division of Reactor Program Management Office of Nuclear Reactor Regulation Technical contacts: Patricia Campbell, NRR (301) 415-1311 E-mail: pic@nrc. gov David Skeen, NRR (301) 415-1174 E-mail: dis @nrc. gov Andrew Dunlop, Rill (630) 829-9726 E-mail: axd7@nrc. gov
Attachment:
List of Recently issued NRC Information Notices I