ML18051B245
| ML18051B245 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 01/28/1985 |
| From: | Johnson B CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| GL-83-28, NUDOCS 8502010044 | |
| Download: ML18051B245 (3) | |
Text
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- Power company General Offices: 1945 West Parnall Road, Jackson, Ml 49201 * {517) 71;18-0550 January 28, 1985
- Director, Nuclear Reactor Regulation US Nuclear Regulatory Connnission Washington, DC 20555 DOCKET 50-255 - LICENSE DPR.e I
PALISADES PLANT - RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION:
GENERIC LETTER 83-28, ISSUE 4.2, PREVENTIVE MAINTENANCE AND SURVEILLANCE PROGRAM FOR REACTOR TRIP BREAKERS On November 7, 1983 and February 3, 1984, Consumers Power Company provided responses to Generic Letter 83-28, Issue 4.2, Preventive Maintenance and Surveillance Program For Reactor Trip Breakers, for the Palisades Plant.
The following response provides clarification regarding the Palisades reactor trip system, as described in the previous responses.
Also included in this submittal is information addressing the November 26, 198!f.request for additional information regarding our previous responses to Issue 4.2.
Automatic Reactor Trip System The automatic reactor trip system at Palisades consists of four independent measuring channels for each trip parameter.
An individual channel trip occurs when the measured trip parameter reaches a preselected value.
The channel trips are combined into a multiple two-out-of-four logic matrix.
Upon receipt of a two-out-of-four channel trip, the logic system causes four contactors to become de-energized, which disrupts AC power to the control rod drive DC clutch power supplies.
The resulting interruption of DC power causes the electromagnetic clutch holding coils to de-energize, allowing the control rods to drop into the core.
The automatic reactor trip system does not utilize reactor trip breakers with undervoltage trip attachments.* The corresponding trip function is provided by the four contactors.
The contactors are Allen-Bradley, Model 702-AC.
Contactors of this type are inherently reliable devices designed for cycling of AC loads.
8502010044 850128 PDR ADOCK 05000255 P
PDR GENLTR-83-28-NL02 I
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Response to Request for Additional Information - Generic Letter 83-28 Issue 4~2, Preventive Maintenance &
Surveillance Program for Reactor Trip Breakers January 28, 1985 2
Allen-Bradley's preventive maintenance recommendations call for a periodic visual inspection, with the frequency based upon environmental and operating conditions, as well as by past experience.
The visual inspection recommendation includes a check for excessive wear and dirt accumulation, replacement of worn or damaged parts and a check for tightness of connections.
Cautions are provided by Allen-Bradley against the use of both lubrication and spray cleaners.
Subsequent contact with Allen-Bradley has resulted in no additional preventive maintenance recommendations.
A preventive maintenance program is currently in place which implements each of the Allen-Bradley recommendations.
The preventive maintenance program is performed on a refueling outage frequency.
No problems were noted during the most recent inspection, which was performed during the 1983/1984 refueling outage.
Manual Reactor Trip System A manual reactor trip is provided to permit the operators to trip the reactor.
Manual actuation of either of two push-button switches in the control room interrupts AC power to the control rod drive DC clutch power supplies.
One manual trip push button interrupts control power to the holding coils of the contactors, whose contacts break AC power to the clutch power supplies.
The second manual push button interrupts voltage to the undervoltage coils of two circuit breakers, resulting in a disruption of AC power to the clutch power supplies.
The functioning of the circuit breakers to disrupt AC power is associated only with the manual reactor trip, and is independent of the automatic reactor trip.
The circuit breakers are Westinghouse Model D-JA2200, with undervoltage trip.
One of these circuit breakers was shown on Figure 1 of the February 3, 1984 submittal, and was identified as "CB-AB".
The Westinghouse preventive maintenance recommendations call for a periodic visual inspection of the circuit breaker to assure tight connections.
Operating the circuit breaker under load is also recommended to remove any high resistance film which may have formed.
This is accomplished by the inherent wiping action of the moving contacts.
No specific frequency for either the inspection or the operation under load is given.
Westinghouse notes that removing the sealed cover of the JA type circuit breaker voids the Underwriters' Laboratories, Inc. label, and is not recommended.
Subsequent contact with Westinghouse has resulted in no additional preventive maintenance recommendations.
A preventive maintenance program is in place which implements each of the Westinghouse recommendations for JA type circuit breakers.
The preventive maintenance program is performed on a refueling outage frequency.
The circuit GENLTR-83-28-NL02
Response to Request for Additional Information - Generic Letter 83-28 Issue 4.2, Preventive Maintenance &
Surveillance Program for Reactor Trip Breakers January 28, 1985 breakers are operated under load prior to plant start-up, as part of a start-up checklist.
No problems have been noted.
Trending of Reactor Trip Devices 3
Maintenance records resulting from the preventive maintenance program for reactor trip devices are reviewed by system engineers at least every two years.
The system engineer reviews the completed maintenance activities to identify potential trends in equipment and system performance.
Based on the results of the review, the scheduled frequency of the preventive maintenance may be adjusted, as appropriate, to increase system reliability.
Since the preventive maintenance programs for the reactor trip devices have only recently been implemented, and primarily involve visual inspections, specific parameters for trending have not yet been developed.
Specific parameters for trending may be developed in the future, as more maintenance information is accumulated on the reactor trip devices.
Brian D Johnson Staff Licensing Engineer CC Director, Office of Nuclear Reactor Regulation Director, Office of Inspection and Enforcement NRC Resident Inspector - Palisades GENLTR-83-28-NL02