ML20195D213

Requests Review of Draft Info Notice Discussing Failure of Several Preaction Sprinkler Sys Deluge Valves at Farley Nuclear Plant to Ensure That Technical Info Re Event, Accurate

ML20195D213
Person / Time
Site:	Farley
Issue date:	11/12/1998
From:	Dennig R NRC (Affiliation Not Assigned)
To:	Pounder D AFFILIATION NOT ASSIGNED
References
NUDOCS 9811170318
Download: ML20195D213 (9)

Text

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November 12, 1998 Mr. Don:Id B. Pound r Engineering Section Manager l

Research and Development

. Grinnell Corporation l

1467 Elmwood Avenue i

Cranston, Rhode Island 02910

SUBJECT:

REQUEST FOR A TECHNICAL REVIEW OF A DRAFT INFORMATION NOTICE REGARDING INSERVICE TESTING OF THE A-4 MULTIMATIC DELUGE VALVE l

Dear Mr. Pounder:

The U.S. Nuclear Regulatory Commission is planning to issue an information notice (IN) i discussing the failure of several preaction sprinkler system deluge valves at the Farley Nuclear Plant. We ask that you review the enclosed draft of that IN to ensure the technical hformation L

regarding the event is accurate. Your cooperation in this matter is appreciated. Please return any comments you may have by close of business on November 27,1998. 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 l

ATTN: William Burton Mail Stop: 0-12D1 l

Washington, D.C. 20555-0001 Please address any questions you may have on this matter to William Burton of my staff.

Mr. Burton can be reached at 301-415-2853. If no comments are received by the close of business on November 27,1998, we will assume the technical information in the notice is correct.

Sincerely,

{0riginal signed by) 11gK0500034g Events Assessment 8 981112 Robert L. Dennig, Section Chief 1

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Division of Reactor Program Management Office of Nuclear Reactor Regulation

Enclosure:

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OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555-0001 l

November xx,1998 NRC INFORMATION NOTICE 98-XX: FAILED FIRE PROTECTION DELUGE VALVES AND POTENTIAL TESTING DEFICIENCIES IN

- PREACTION SPRINKLER SYSTEMS l

Addressees L

' All NRC licensees.

Purpona The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert addressees to test methodologies for fire protection deluge valves that may not adequately demonstrate valve operability. 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.

Backaround Valves for sprinkler system automatic control (SSAC) valves are used h fire protection systems that protect areas housing safety-related equipment and that also protect non-safety-related equipment used for safe shutdown. Many of these systems are used to provide primary fire protection and to meet the requirements of 10 CFR Part 50, Appendix R, Section lil.G. Poor design, deficient maintenance, or inadequate testing of SSAC valves and associated solenoid valves can lead to a common-mode failure of the valves to perform their design function of providing adequate and reliable fire protection. This, in turn, can result in the failure of safety-related equipment and the inability to achieve and maintain a safe reactor shutdown condition if a fire occurs.

The Model A-4 Multimatic Valve manufactured by Grinnell is a deluge valve designed for use in -

fire protection systems, it is used as a system control valve in deluge, preaction, and special types of fire protection systems and may also provide for actuation of fire alarms when the systems operate.

Preaction valves contain connections for monitoring pressure in the diaphragm chamber and in f

the main water supply, for providing valve drainage and for supplying water to the diaphragm chamber. All required components for these connections are typically provided by the valve manufacturer as " trim packages" and are included as part of the Underwriters Laboratories (UL) i

- and Factory Mutual, Inc (FM) certifications of the valves.

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J IN 98-XX W,

November XX,1998

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Descriotion of Circumstances l

During the week of March 4,1996, while of reaction sprinkler systems in the Farley Unit 1 fire protection system were being tested,5 of 11 SSAC valves (Grinnell Model A4 deluge valves) failed to trip open when water pressure was vented out of the diaphragm chamber. During additional testing, the licensee found that several more SSAC valves failed. A root cause team, formed after the initial valve failures, concluded that the diaphragm was sticking to its retainer and push rod disk, that the push rod assembly was worn (pits and eroded plating), and that the associated solenoid valves were not properly bleeding water pressure out of the diaphragm area.

The investigators found that the licensee was using an abrasive cleaning pad to clean the chrome-plated push rod and the push rod guide in the diaphragm retainers. The team theorized that this activity may have created rust particles that caused the sticking. Abrasives were also used to clean the solenoid valves, this could cause the plunger assembly to stick.

Grinnell does not recommend using any abrasives that remove metal because the solvents attack the valve seats and the main orifice. Grinnell recommends cleaning the push rods and guides with only soap, water, and clean rags.

The root cause team also found that the solenoid valves were designed for operating pressures of approximately 150 psig (UL maximum rated pressure is 175 psig), whereas the actual operating pressures often exceeded 150 psig (sometimes as high as 225 psig). The valves may not be able to open against this pressure. Finally, the team found that the licensee lubricated the diaphragm and retainer to Ireep the retainer from sticking. Grinnell does not recommend the use of any lubricant on the diaphragm or the retainer.

During subsequent walkdowns, the team found that the piping for the deluge valve control drain lines was 3/8 inch, the % inch normally supplied as part of the trim package provided by the manufacturer and listed by the independent testing laboratory (i.e., UL or FM). The use of a smaller drain line could potentially inhibit the bleedoff of water from the diaphragm chamber resulting in increased pressure in the chamber. This condition, in turn, could prevent the clapper from opening. The licensee used its own trim in lieu of the package provided by Grinnell.

Although the team did not reach any conclusion about the root cause of the valve failures, it recommended (1) replacing the diaphragms and solenoid valves, (2) installing new solenoid valves with a design pressure of 200 psi (and factory tested to 300 psi), (3) flushing the solenoid valve piping and diaphragm chamber when cleaning the solenoids, (4) requiring the use of soap, water and a clean cloth when cleaning the solenoid valves, (5) cleaning the solenoid and SSAC valves more frequently, and (6) testing the valves more often every 12 months instead of 18 months (in the short term, the licensee increased testing to every 2,6, and 12 months after resetting the valves to improve reliability).

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IN 98-XX November XX,1998 Page 3 of 5 in mid-February 1998, the licensee performed a scheduled surveillance test on several deluge valves in the preaction sprinkler system deluge valves. One valve failed to trip and was manually tripped by forcing the push rod back. Inspection of the rubber diaphragm showed a

" dimple" near the diaphragm chamber supply inlet. The valve had been left in the tripped condition for about 22 days in May 1997, then it was reset and left in this position for about 9 months until this surveillance. As a result of this failure, the licensee tested a sample of six additional valves that had been left in a tripped condition for long periods. One of these failed to trip electrically. Inspection of this valve indicated that the push rod was misaligned in the retainer ring slot and that some corrosion had formed where the rod slides through the ring.

Also, the diaphragm was stuck to the face of the push rod. in total, five of the six sample valves and one other valve failed to trip properly. The licensee's description of the diaphragm problems are shown in Attachment 1, Figures 1-3.

In June 1998, as part of the ongoing testing program, one of the deluge valves was manually actuated from its pull station, it failed to operate. An investigation indicated that the pull station housing had rotated and was preventing complete travel (i.e., fully open) of the valve handle.

After edjusting the pull station housing, the handle was actuated again and the deluge valve successfully tripped.

The staff is continuing to monitor the licensee's investigation into the valve failures.

Discussion Several potential problems were identified as a result of this event. First, as discussed above, f

when deluge valves were left in the tripped condition for long periods, the rubber diaphragm could bond to the push rod and the flange. When the valves are reset, the diaphragm may remain partially bonded to the flange, restricting flow from the diaphragm chamber, thus keeping the valve from operating. Bonding may be particularly pronounced in systems using well water or raw river water. It is a common practice for many plants to keep their preaction sprinkler system deluge valves in a tripped condition for long periods, usually during outages when welding or other activities are occurring, which increases the likelihood of spurious system actuation. Grinnell recommends that the valve be reset within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of any valve operation and that the internal components of valves be cleaned and inspected after any valve operation.

Second, the use of plant-supplied or plant-designed trim packages instead of the UL-or FM-certified packages and designs provided by the valve manufacturer may result in issues such as undersized drain lines, which may restrict the bleedoff from the diaphragm chamber and further inhibit valve actuation.

Third, an evaluation by Grinnell concluded that the valve release mechanism may be jamming from the high pressure and surging conditions in the deluge system. The jamming may be related to deep indentations on the valve latch. Cleaning and inspection of the valves intemal components should identify these potential problems.

Finally, while reviewing this event, the staff noted a potential weakness in the testing j

methodology for preaction deiuge valves, which may mask the actuation problems identified i

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IN 98-XX November XX,1998 l '-

Page 4 of 5 1

above. Many plants isolate the deluge valves from the main water supply during valve testing.

j With the deluge valve isolated, a limited volume of water is trapped in both the main line and the diaphragm chamber supply line. The water in the diaphragm chamber is slowly bled off until the clapper opens. If the diaphragm has bonded to the flange, the inlet to the diaphragm chamber could be partially blocked, inhibiting (but not preventing) bleedoff from the diaphragm chamber during testing. However, during normal operation with full flow from the diaphragm chamber supply line, the primary flow path would be from the supply line to the drain, thus trapping water in the diaphragm chamber and preventing valve actuation. Note that National Fire Protection Association (NFPA) Standard 25, " Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems," 1995 edition, section 9-4.3.2.2 states:

"Each deluge or preaction valve shall be trip tested annually at full flow (emphasis added)in warm weather and in accordance with the manufacturer's instructions." The valve manufacturer may also have special requirements for inservice testing.

1 A similar event, which took place at Grand Gulf in 1983, is discussed in Information Notice (IN) 8416," Failure of Automatic Sprinkler System Valves to Operate." While the licensee was performing an operational test of the emergency diesel generator (EDG), a fire occurred in the diesel. The automatic deluge valve (6-inch Model C valve manufactured by the Automatic Sprinkler Company of America (ASCO)) failed to open. Approximately 3 months later, a Model C valve in a preaction sprinkler system for the EDG room at Grand Gulf failed to operate during t

a test. In both cases, scoring was found in the actuation weight upper guide collar and in the box that encloses the weight guide bushing.

Another instance of repeated failures of a preaction deluge valve occurred in 1997 at Limerick Unit 1. A Star Model"D" 6-inch deluge valve did not actuate during a surveillance test. The t

frequency of testing had been increased because of earlier failures due to suspected mechanical problems. Continued troubleshooting of the valve failures identified a potential voltage mismatch between the deluge valve and the Chemetron release control panel, resulting in marginal power available to operate the valve. The Model"D" valves were subsequently replaced with Star Model "G" valves.

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November XX,1998

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Page 5 of 5 M

r Related Generic Communications y

9 information Notice (lN) 84-16, " Failure of Automatic Sprinkler System Valves to Operate." issued March 2,1984.

9 IN 92-28, " inadequate Fire Suppression System Testing," issued April 8, 1992.

9 IN 97-22, " Potential for Failure of the OMEGA Series Sprinkler Heads," issued j

September 22,1997.

l This information notice requires no specific action or written response. However, recipients are reminded that they are required to consider industry-wide operating experience (including NRC information notices) where practical, when setting goals and performing periodic evaluations j

l-under 10 CFR 50.65, " Requirement for monitoring the effectiveness of maintenance at nuclear power plants." If you have any questions about the information in this notice, please contact the technical contacts one by listed below or the appropriate Office of Nuclear Reactor l

Regulation (NRR) project manager.

l Jack W. Roe, Acting Director Division of Reactor Program Management Office of Nuclear Reactor Regulation i

Technica; contacts: Mark H. Salley, NRR Robert Caldwell, Ril l

301-415-2840 334-899-3386 l

E-mail: mxs3@nrc. gov E-mail: rkci@nrc. gov William F. Burton, NRR 301-415-2853 E-mail: wfb@nrc. gov

Attachment:

List of Recently Issued NRC Information Notices i

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