ML20049H245
| ML20049H245 | |
| Person / Time | |
|---|---|
| Site: | Monticello, Dresden, Davis Besse, Palisades, Perry, Fermi, Kewaunee, Point Beach, Byron, Braidwood, Prairie Island, Callaway, Duane Arnold, Clinton, Cook, Quad Cities, La Crosse, Big Rock Point, Zion, Midland, LaSalle, 05000000, Zimmer, Bailly, Marble Hill |
| Issue date: | 03/26/1982 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| IEIN-82-08, IEIN-82-8, NUDOCS 8202040113 | |
| Download: ML20049H245 (4) | |
Text
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SSINS Nc.:
6835 Accession No.:
8202040113 IN 82-08 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMEh7 WASHINGTON, D.C.
20555 March 26, 1982 IE INFORMATION NOTICE NO. 82-08:
CHECK VALVE FAILURES ON DIESEL GENERATOR ENGINE COOLING SYSTEM Description of Circumstsnces:
On October 23, November 19, and December 1, 1981, the Dresden Station experienced events concerning degradation of the Unit 2/3 and Unit 3 diesel generator (DG) cooling water systems. The Unit 2/3 DG is a single diesel generator that can be electrically aligned to serve either Unit 2 or Unit 3.
The Unit 3 DG serves only Unit 3.
At approximately 0217 on October 23, 1981, a monthly DG surveillance test was commenced on the Unit 2/3 DG.
The diesel was started normally from the control room. At approximately 0224, the Unit 2/3 DG tripped on high engine temperature.
Cooling water flow to the DG heat exchanger was found to *ve inadequate. Attempts to restore adequate water pressure to the DG heat exchanger were unsuccessful and Unit 2/3 DG was declared inoperable. At approximately 0400, surveillance was commenced on the Unit 3 DG.
Indications of insufficient cooling water flow were observed and a DG shutdown was commenced by the control room operators at about 0407. A few seconds later, the diesel tripped on high engine temperature.
The Unit 3 DG cooling water pump (DGCWP) was cycled several times, during which time the pump was vented. At about 0417, immediately after one of the pump starts, Unit 3 DGCWP discharge pressure increased and the observed DG heat exchanger pressure returned to normal. The pump was cycled several more times without incident. A hot restart of the Unit 3 DG was then conducted, and the DGCWP and DG functioned normally. The Unit 2/3 DGCWP was then tested, found to operate satisfactorily and returned to service.- Because of the unusual nature of the event, the licensee agreed to conduct daily surveillance tests on the Unit 2/3 and Unit 3 DGCWPs for 7 days while investigating the event.
At about 0453 on November 19, during a surveillance test of the Unit 3 DG, the diesel tripped on high engine temperature. The Unit 3 DGCWP was declared inoper-able and the Unit 3 DG was removed from service. Dresden Unit 3 then operated under a Technical Specification limiting condition for operation while the event was investigated. On November 23, 1981, a broken check valve on the discharge of the Unit 3 DGCWP was found and replaced. The valve disc had broken free of the pivot arm and was lodged in the discharge side of the valve, restricting 1
nearly all flow. The valve was replaced and DG 3 was returned to service. The failure of the 2/3 DGCVP on October 23 was not yet explained.
On December 1, 1981, the Unit 2/3 DGCWP exhibited a slow decrease in indicated discharge pressure accompanied by increasing noise and vibration levels at the pump. This decrease in indicated pressure and the increase in noise and vibra-tion levels were later determined (through visual inspection, testing, and deter-i mination of actual bearing clearance) to have been caused by excessive wear of 8707.c44 0 tI 3
IN 82-08 March 26, 1982 Page 2 of 2 the DGCWP bearings. The pump was replaced. During the pump replacement, the licensee inspected the Unit 2/3 DGCWP discharge check valve and found it was broken. As was the case with the Unit 3 punp discharge check valve, the disc had broken free of the pivot arm.
In the instance of the Unit 2/3 pump, however, the disc had not lodged into the body of the valve, but was free to move in any direction within the valve body.
Although the Unit 2 diesel had functioned properly throughout the foregoing events, the discharge check valve for the Unit 2 DGCWP was inspected, found to be broken, and replaced.
In the case of the Unit 2 DGCWP discharge check valve, the pivot arm remained attached to the valve disc, but was broken at the hinge to the valve body.
All three DGCWP systems at Dresden Units 2 and 3 involved check valve failures which were discovered during e short period of time.
These failures were not adequately characterized by operator observations and-instrument readings during diesel generator surveillance tests, but were discovered by direct inspection of the internals of the check valve.
It is not known how long these check valves were broken before their condition was detected since the broken valve discs were free to move within the valve bodies and may have been that way for some time before coming to rest in a position which would restrict flow enough to cause the diesel to trip on high engine temperature. Tne sub-ject check valves are horizontally mounted Crane, 8-inch, tilting-disc check valves, Type 373, and have a pressure rating of 125 psi.
This information is provided as notification of a potentially significant matter.
It is noted that these check valves are not routinely covered by inservice testing programs or routine surveillances to verify valve operability.
It is expected that recipients will review the information for possible appli-cability to their facilities. No specific action or response is requested at this time.
If you have questions regarding this ma+ter, please contact the Regional Administrator of the appropriate NRC Regional Office.
Attachment:
Recently issued IE Information Notices l
l l
t
Attachment IN 82-08 March 25, 1982 RECENTLY ISSUED IE INFORMATION NOTICES Information Date of Notice No.
Subject Issue Issued to 82-07 Inadequate Security Screening 03/16/82 All power reactor Programs facilities holding an OL or CP 82-06 Failure of Steam Generator 03/12/82 All power reactor Primary Side Manway Closure facilities holding Studs an OL or CP 82-05 Increasing Frequency of 03/10/82 All power reactor Drug-Related Incidents facilities holding an OL or CP 82-04 Potential Deficiency of 03/10/82 All power reactor Certain AGASTAT E-7000 facilities holding Series Time-Delay Relays an OL or CP 82-03 Environmental Tests of 03/04/82 All power reactor Electrical Terminal Blocks facilities holding an OL or CP 82-01 Auxiliary Feedwater Pump 02/26/82 All power reactor Rev. 1 Lockout Resulting from facilities holding Westinghouse W-2 Switch an OL or CP Circuitry Modification 80-32 Clarification of Certain 02/26/82 All facility, Rev. 1 Requirements for Exlusive-materials and Use Shipments of Radio-Part 50 licensees active Materials 82-02 Westinghouse NBFD Relay 01/27/82 All power reactor Failures in Reactor facilities holding Protection Systems at an OL or CP Certain Nuclear Power l
Plants l
l 82-01 Auxiliary Feedwater Pump 01/22/82 All power reactor l
Lockout Resulting from facilities holding Westinghouse W-2 Switch an OL or CP Circuit Modification l
l l
j OL = Operating License CP = Construction Permit l
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Y fQgf>f *. P.elyI00 K 1N-D O.
a, 500.1*. M D W l
American Electric Power Service Corporation y $y-g D. C. Cook 1, 2 (50-315, 50-316)
Cincinnati Gas and Electric Company Zimmer (50-358)
The Cleveland Electric Illuminating Company Perry 1, 2 (50-440, 50-441)
Commonwealth Edison Company Braidwood 1, 2 (50-456, 50-457)
Byron 1, 2 (50-454, 50-455)
Dresden 1, 2, 3 (50-10, 50-237, 50-249)
La Salle 1, 2 (50-373, 50-374)
Quad-Cities 1, 2 (50-254, 50-265)
A Zion 1, 2 (50-295, 50-304)
Consumers Power Company RECElyEO Big Rock Point (50-155)
Palisades (50-255) t APRg g b Midland 1, 2 (50-329, 50-330)
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Dairyland Power Corporation LACBWR (50-409)
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ro The Detroit Edison Company Fermi 2 (50-341)
Illinois Power Company Clinton 1, 2 (50-461, 50-462)
Iowa Electric Light and Power Company Duane Arnold (50-331)
Northern Indiana Public Service Company Bailly (50-367)
Northern States Power Company Monticello (50-263)
Prairie Island 1, 2 (50-282, 50-306) l l
Public Service of Indiana Marble Hill 1, 2 (50-546, 50-547) l Toledo Edison Company Davis-Besse 1 (50-346)
Union Electric Company l
Callaway 1, 2 (40-483, 50-486) l Wisconsin Electric Power Company Point Beach 1, 2 (50-266, 50-301)
Wisconsin Public Service Corporation Kewaunee (50-305)
Illinois Department of Nuclear Safety l
Gary N. Wright, Manager, Nuclear Facility Safety
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