ML20086G819
| ML20086G819 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 07/07/1995 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9507170182 | |
| Download: ML20086G819 (5) | |
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CORRECTED Towphon. (205) 868 5131 COPY Southern Nudear Operating Company o... uo,.y Vce Present the southern electic system F.rsey Propct July 7, 1995 Docket Numb 6r:
50-364 10 CFR 2.201 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Joseph M. Farley Nuclear Plant - Unit 2 Reply to Notice of Violation NRC Insoection Reoort No. 50-364/95-10 As requested by your transmittal dated June 8,1995, this letter msponds to violation (VIO) 50-364/95-10-02,"OTDT Channel 2A Setpoint Failed High." h Southern Nuclear Operating Company (SNC) response to VIO 50-364/95-10-02 is provided in the Attachment.
I affirm that the response is true and complete to the best of my knowledge, information and belief.
Respectfully submitted.
l}btk hll Dave Morey l
REM /maf:NOV95101. DOC Attachment cc:
Mr. S. D. Ebneter Mr. B. L. Siegel Mr. T. M. Ross i
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I ATTACHMENT RESPONSE TO VIO 50-364/95-10-02 i
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Violation 50 364/95-10-02 states the followmg:
d The Limiting Condition for Operation for Technical Specification 3.3.1, Table 3.3-1 requires I
that three channels of Overtemperature Delta Temperature (OTDT) shall be operable during Modes 1 and 2 for three loop operation. When less than the total number of channels (i.e.,
three) are operable, Action statement number 7 requires that the inoperable channel is to be placed in a tripped condition within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
i Contrary to the above, the licensee operated Unit 2 in Mode I with the Loop 2A OTDT channel inoperable (i.e., OTDT setpoint fai!ed high) from April 29 through May 7,1995. On May 7. the Loop 2 A OTDT channel was declared inoperable and placed in a tripped condition.
This is a Severity Level IV violation (Supplement I).
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Admission or Denial De violation occurred as described in the Notice of Violation.
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Reason for Viointion An investigation detennined that the deviation was attributable to personnel error. An individual inadvertently adjusted an inappropriate potentiometer while performing a nuclear instrumentation calibration.
A review of plant data was performed to detennine at what time the 2A Loop OTDT channel became inoperable. He as-found setting for the Loop 2A OTDT channel indicated that the associated pressurizer pressure input potentiometer had apparently been inadvertently adjusted to an out of tolerance setting during a nuclear instrumentation calibration performed during post-refueling adjustments on 4/29/95 when Unit 2 was operating at approximately 33 percent power. The pressurizer pressure input potentiometer associated with the Loop 2A OTDT channel is located on a common card and adjacent to the potentiometer which should have been adjusted during nuclear instrumentation adjustments. This inadvertent adjustment resulted in the 2 A OTDT channel having a reactor trip setpoint outside the limitations for operability.
However for the plant conditions that existed at that time it was not recognizable as being inoperable using nonnal control room indications. Control room channel indicators for the Loop OTDT channels indicate approximately 150% of AT (upper end of the indication band) at 33 percent power. Herefore, the inoperable channel was not placed in the trip condition within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> as required by Technical Specifications 3 3.1.
Additional information As part of the review findmgs. it was found that on two occasions, prior to discovery of the inoperable OTDT channel. reactor power was raised to a sufficient level where a deviation between the channels could be discerned. Channel checks were perfonned and documented on these occasions during performance of Operations Daily and Shift Surveillance Requirements. FNP-2-STP-1.0. On the first occurrence, May 2, 1995, channel 2 A was at the top of the scale indicating 150% while the remaining two channels had come on scale and were indicating 145%. STP-l.0 is perfonned once every 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> shift and provides guidance to the operator for detennining allowable deviations between channels when performing channel checks. The expected deviation listed in STP-1.0 for OTDT is 7.5%. The maximum allowable deviation listed is
1 RESPONSE TO VIO 50-364/95-10-02 Page 2 18.8%. For channel checks resulting in deviation of greater than 7.5% up to and including 18.8% the channel is considered operable; however, investigative and corrective action should be initiated by the operator if deviations are found to be within this range. For values greater than 18.8%, the control room team should declare the channel inoperable, perfonn required Technical Specification actions and initiate corrective action. The channel check performed on May 2,1995 found the deviation to be 5%. Since the deviation was less than 7.5% no action was required and failure to discover the misalignment at this time does not constitute unacceptable awareness.
On the evening shin of May 6.1995 reactor power was raised again to a level where deviation between channels could be discerned. A channel check was performed per FNP-2-STP-1.0. Channel 2A was again found at the top of the scale indicating 150% while the other two channels were found indicating 138%.
The Operator At The Controls identified the variation between channels had exceeded the expected deviation of 7.5%. However. the Operator At The Controls failed to perfonn his responsibilities as expected in that the individual did not implement corrective action, follow up on the indication, or inform the rest of the main control room team. The other main control room team members failed to meet management expectations in that they did not recognize that the expected variation had been exceeded during their reviews of the surveillance test and did not initiate corrective action. Reactor power ascension was in progress and continued through the evening and the night. Main control room crew shin relief was perfonned at approximately 2300 hours0.0266 days <br />0.639 hours <br />0.0038 weeks <br />8.7515e-4 months <br />. A deviation between the channels was not identified by the individual crew members during their control board walkdowns. A channel check is not required during control board walkdowns, however, detection at this time would have been possible and desirable. He night shift main control room crew perfonned STP-l.0 as part of their shift routine and found that the deviation between channels had increased to approximately 20%. The crew declared 2A OTDT channel inoperable, perfomied Technical Specification actions and initiated corrective actions for the failed channel.
Corrective Actions Taken nnd Results Achieved De channel was adjusted and returned to service on May 7,1995 at 0430 hours0.00498 days <br />0.119 hours <br />7.109788e-4 weeks <br />1.63615e-4 months <br />.
LER 95-003 (Unit 2 ) was written for this incident.
De individual that apparenth adjusted the inappropriate potentiometer has been coached concerning this incident.
The lessons learned from this incident concerning adjustments of potentiometers have been presented to other technicians in 1/C shop information meetings.
The necessity to utilize self-verification techniques has been discussed with the personnel that performed the nuclear instrumentation adjustments and with other technicians in shop information meetings.
Operation crews have been made aware of the failures of operations personnel to perform as expected via Standing Orders and meetings held with operations management and operations crews.
Operations personnel im ohed has e been coached
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RESPONSE TO VIO $0-364/95-10-02 Page 3 Crew personnel utre reminded of the requirements of STP-1.0 concerning channel deviations and the g'
importance of utilizing all opportunities to identify control board discrepancies and the appropriate actions to take.
Corrective Steps to Avoid Further Violation j
Licensed personnel will be trained on this event.
Date of Full Compliance September 16.1995 a
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