05000029/LER-1985-007, Forwards LER 85-007-00

Forwards LER 85-007-00

ML20137E203
Person / Time
Site:	Yankee Rowe
Issue date:	01/03/1986
From:	St Laurent N YANKEE ATOMIC ELECTRIC CO.
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
NUDOCS 8601170196
Download: ML20137E203 (1)

LER-2085-007, Forwards LER 85-007-00

Event date:
Report date:
0292085007R00 - NRC Website

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l YANKEE ATOMIC ELECTRIC COMPANY Rowe, Massachusetts 01367 Y,

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January 3, 1986 U.S. Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, Pennsylvania 19406 Attention: Dr. Thomas E. Murley, Regional Administrator

Subject:

Licensee Event Report 50-29/85-07, Revision 0 Nuclear Instrumentation Channels 7 and 8 Low Power Set Points Inoperative

Dear Sir:

In accordance with 10 CFR 50.73(a)(2)(v)(A) and 50.73(a)(2)(vii)(A), the attached Licensee Event Report, is hereby submitted. A three-day extension for submittal of this report was provided via telephone conversation of the Resident Inspector and your office.

Very truly yours, h61 & h I~ Glulx Normand N. St. Laurent Plant Superintendent DWE/nm Enclosure cc: [3] NSARC Chairman (YAEC)

[1] Institute of Nuclear Power Operations (INP0)

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At 2230 hours0.0258 days <br />0.619 hours <br />0.00369 weeks <br />8.48515e-4 months <br /> on December 1,1985, while in Mode 5 at zero percent power, nuclear instrumentation power range ch,innels 7 and 8 were found to exceed Technical Specification (TS) 2.2-1 for the low power range trip setpoint. The discovery was made during calibration of the power range channels during the 1985 refueling outage.

Telephone notification to the NRC Operations Center was made at 2315 hours0.0268 days <br />0.643 hours <br />0.00383 weeks <br />8.808575e-4 months <br />.

Corrective Actions consisted of investigation, repair, and satisfactory calibration and functional test of the power range channels 7 and 8. The investigation revealed two solder terrinals that were not making proper electrical contact. Repair consisted of resoldering the terminals using appropriate technique. Corrective Actions to prevent recurrence was the investigation and inspection of similar terminals. All nuclear instrumentation channels were operable following calibration at the end of the 1984 refueling outage. The power range channels were functionally tested on 11/13/84 following a reactor scram as required. Functional testing for the low power range trip at greater than 15 MWe would cause a reactor scram.

Accordingly, a proposed change to Technical Specifications will be submitted to more clearly specify functional testing for the high and low power range trip. There was no adverse affect to the public health and safety due to this event.

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0l0 0 l2 or 0l3 TEXT (# mye space a mgawv4 ese admannaf ARC Form Je6Nat IIM At 2230 hours0.0258 days <br />0.619 hours <br />0.00369 weeks <br />8.48515e-4 months <br /> on December 1,1985, while in Mode 5 and zero percent power, the low trip set point of nuclear instrumentation power range cha'nnels 7 and 8 were found to exceed Technical Specification (TS) 2.2-1. The discovery was made by a technician performing calibration of the power range channels.

One hour telephone notification to the NRC Operations Center was made at 2315 hours0.0268 days <br />0.643 hours <br />0.00383 weeks <br />8.808575e-4 months <br />.

The nuclear instrumentation channels are an integral part of the Reactor Protection System (RPS). The channels consist of the following: source range (channels I and 2); intermediate range (channels 3 and 4); power range (channels 6, 7 and 8); and intermediate power range (channels 3, 4 and 5).

During calibration on 12/1/85, the low trip set point of power range channels 7 and 8 were found to be 104 and 106 percent respectively. For these channels, TS 2.2-1 specifies s 35 percent for the low trip set point and s 108 percent for the high trip set point.

Investigation of this condition revealed two solder joints that appeared to have been cold soldered. The two solder joints were not making an adequate electrical contact.

Further, thes, terminals are part of the switching circuitry for scram set relay K1301. Normally, the relay switches the scram set points from high power (s 108 percent) to low power (s 35 percent) range, as applicable, for power operation. The relay is activated high or low via the manual power scram set switch.

These channels are required to be operable by surveillance following a reactor scram.

Review of documentation reveals the channels to have been operable as required on l 11/13/84 after a reactor scram and prior to resuming power operation. l Technical Specifications operability and surveillance requirements for the power I range channels are applicable in Modes 1 and 2, with the scram breakers in the closed i position and the Control Rod Drive System capable of rod withdrawal. Depending upon the time that the condition of the solder joints evolved, the operability requirements for channels 7 and 8 low scram set point may not have been met.

Relative to these circumstances, a review of Technical Specifications has been performed. As a result of this review, a proposed change to Technical Specifications ,

will be submitted to more clearly specify functional testing for the RPS high and low ,

scram set trip. The change is necessary since functional testing for the low scram set trip is not practical in Mode 1 at greater than 15 MWe, such testing would result in a reactor scram. Testing of the low scram set trip is performed during precritical surveillance.

The safety consequences and implications of the possibly inoperable low trip set points for power range channels 7 and 8 are as follows. The low scram set trip is a feature of the RPS at power levels of s 15 MWe and with the coincidence selector switch in the coincidence position, this feature is not assumed in any of the accident analyses. At power levels of s 15 MWe, two trip signals of the three power range channels must be present for initiation of automatic scram. Power range

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_ MC Form Js6A sit 17) channel 6 is known to have been operable, while channels 7 and 8 may not have been.

Therefore, the automatic scram feature of the RPS may not have been available at s 15 MWE, if required.

Corrective Action consisted of the noted investigation, repair of the solder joints using adequate soldering technique, satisfactory channel calibration and channel functional test. Corrective Actions to prevent recurrence consisted of inspecting the remaining terminals of K1301 and similar relay K1302. Additional Corrective Action will be the submittal of the noted proposed change to Technical Specifications.

• The apparent failure mechanism of this condition was the cold solder terminals later causing inadequate electrical contacts for K1301.

The circuitry involved is original plant equipment. The relay and contacts are part of Westinghouse Auxiliary Meter Panei serial number 1Y. The relay was made by Couch, and is a rotary 4 pdt type 4A37-B, with the coil rated 3A @ 120 VDC and 60-400 Hz.

The contacts are rated 3A 0 30 VDC.

There was no adverse affect to the public health and safety due to this event.

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