ML20133D685
| ML20133D685 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 03/29/1985 |
| From: | Tucker H DUKE POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8507220273 | |
| Download: ML20133D685 (9) | |
Text
.~
.. ~. ~ ~ - - -
'O e
I DUKE Powna COMPANY P.O. NOx (MHep CHAR 8MrFM. M.C. 94Mt.Mt HALB.TUCKEN ic e nuenuswn
= - ". _
s J tti',1 4 t, J0 tro43 ora-4n:n l
.l2 l
March 29, 1985'
(
1 l
l Dr. J. Nelson Grace, Regional Administrator U. S. Nuclear Regulatory Coasnission l
Region 11 7
1 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 i
Subject:
McGuire Nuclear Station l
Docket Nos. 50-369 and 50-370
Reference:
RII:RP NRC/01E Inspection Report 50-369/84-40 and 50-370/84-35 t
Dear Dr.' Grace:
Pursuant to 10 CFR 2.201, please find attached a response to Violations 50-370/84-35-01, 50-370/84-35-02 and 50-370/84-35-03 which were identifLed in the above referenced inspection report. Note that these events were the subject of Licensee Event Reports (LER) 370/84-30 and 370/84-31 which were submitted December 26, 1984. Duke Power Company does not consider any information contained in this report to be proprietary.
Very truly yours,
[d/
l H. B. Tucker PBNamjf
[
Attachment l
cc
=Mr. W. T. Orders Senior Resident Inspector - NRC McGuire Nuclear Station l
)
i i
i W"i38H828886 0
.EEo j h
l l
DUKE POWER COMPANY l
McGUIRE NUCLEAR STATION RESPONSE TO NRC/01E INSPECTION REPORT 50-369/84-40 AND 50-370/84-35 Violation 50-370/84-35-01, Severity Level IV (Supplement I):
10 CFR 50. Appendix B Criterion V requires that activities affecting quality be prescribed by documented instructions, procedures, or drawings which shall i
include appropriate quantitative or qualitative acceptance criteria for deter-l mining that important activities have been satisfactorily accomplished.
t 10 CFR 50, Appendix B, Criterion XI requires that testing be performed to demonstrate that structures, systems, and components will perform satis-factorily in service.
Contrary to the above, the licensee failed to provide an adequate procedure necessary to ensure that the Overpower AT Derivative Cards were correctly installed. Additionally, the Overpower AT Reactor Trip System Instrumenta-tion was not tested in a manner that would confirm that the system would perform satisfactorily. Specifically, testing with a decreasing T was not performed on the initial or periodic testing of the Overpower ST renc-g tor protective circuit.
Response
1.
Admission or denial of the alleged violations:
Duke Power Company agrees that procedures were inadequate to insure that JA jumpers would be installed in the OPAT circuits correctly and that the OPAT reactor protective circuit was not tested with a decreasing Tavg
- 2.
Reasons for the violations if admitted:
Duke personnel were aware that the output of the OPAT process control lead lag (NLL) card was unipolar (output positive). Ilowever, in all other applications at McGuire, except for the OPAT circuits, unipolar operation of the lead lad circuit can adequately be accomplished by une of the hard-wired diode without the JA jumper.
There are approximately 80 NLL circuit cards per unit with only the four OPAT NLh cards requiring the "JA" jumper.
Installation of the jumper does not degrade the function of the circuit in all our other lead-lag unipolar applications.
Installa-tion of the JA jumper was not considered significant because of the abovo factors and not knowing of the significanco of the JA jumper in the OPAT circuit, therefore no guidance was given to the technicians. Other jumpers are installed in circuit cards to obtain thu specific gain, blas, and other typical card functions as part of the card setup and calibration. The Westinghouse documentation explaining this circuitry does not give expli-cit guidance concerning the use of the "JA" jumper in this application.
The schematic drawing of the OPAT circuitry does not show a "JA" jumper in this application. None of the other W *inghouse documents that give
4
[
. information about the use of the "JA" jumper directly requires the place-ment of the "JA" jumper in the circuitry for OPAT. The schematic drawing of the OPAT circuitry indicates not to use this "JA" jumper. Due to lack of explicit vendor information. and the reasons listed above, the proced-ures did not contain the subject matter necessary to insure the JA jumper installation.
'the OPAT reactor trip system instrumentation was not tested in a manner that would confirm that the system would perform satisfactorily due to inadequate guidance in the preoperational test procedure and the cali-t bration procedure used to check out the OPAT circuitry. These procedures l
did not verify the function of the " low-limiting" circuitry. The reason l
the procedural deficiencies occurred is that the Westinghouse documents
(
used in the procedure development did not give explicit guidance for use of the " low-limiting" (JA) jumper in the OPAT circuitry. The above l
Westinghouse documentation was all that was available for use in the I
<*evelopment of the preoperational test and the loop calibration procedure.
l These tests did not include checking for the presence of the "JA jumpers" and did not test the OPAT setpoint with a decreasing Tavfy that at a input.
In all loop calibrations, the purpose of the testing is to veri l
determined setpoint the required action occurs.
In the OPAT tests, a positive Tavg input was applied to the circuitry and the OPAT setpoint moved towards the AT process value. Testing in the negative direction would only have checked the ability of the circuit to hold the output at zero volts.
Additional information is contained in LER 370/84-30.
3.
Corrective steps which have been taken and the results achieved:
"JA" jumpers were installed in channels A and D NLL circuit boards.
Procedure to set up cards for OPAT changed to verify the installation of the "JA" jumper on the OPAT circuit as well as all other needed jumpers. Unit 1 OPAT circuits were verified to have "JA" jumpers installed.
l All loops utilizing a lead lag card were reviewed for the applicability of the "JA" jumper. No other loops required the jumper for proper channel actpoint response. All other jumper applications were checked to determine if present testing would identify a missing jumper. The input / output checks completed-under existing procedures verifies all other jumpers are installed correctly. No JA jumpers have i
been omitted since the procedure changes.
Procedure to check card function for OPAT changed to include a step for testing a decreasing T input signal. The loop circuit operation with ay a decreasing Tayg input !ignal was tested to verify the OPAT octpoint responded correctly to a decreasing T va input.
a Appropriate information was covered with all IAE techniciano involved in process control maintenance (January,1985).
l l
l i
. l l
4.
Corrective steps which will be taken to avoid further violations:
Procedures on the Process Control System are being reviewed for consis-tency and human factors. A procedure philosophy and methodology guideline for the Process 7300 System is being written to ensure consistency and uniformity. All 7300 system procedures are to be rewritten to conform to this guideline. Tha schematic drawing of the OPAT circuitry will be updated to show the "JA" jumper installed.
5.
Date when full compliance will be achieved:
The procedure which specifies the correct JA jumper was changed in December,1984 to require the JA jumper in this application.
Procedures to check the specific lead-lag card function were changed in December,1984 to check for correct card output with a decreasing T
input.
avg The station is presently in full compliance with the code of Federal regulation requirements in this area.
Violation 50-370/84-35-02 Severity Level IV (Supplement I):
Technical Specification 3.3.1 requires that the Overpower AT Reactor Trip System Instrumentation Channels of Table 3.3-1 be operabic when the reactor is operated in Modes 1 and 2 and states that a minimum of three channels are required for startup and/or power operation.
Technical Specification 3.0.3 requires that when a Limiting Condition for l
Operation (LCO) is not met, except as provided in the associated ACTION requirements, within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> action shall be initiated to place the unit in a Mode in which the specification does not apply.
Contrary to the above, from initial criticality on May 8,1983 to November 26, 1984 Unit 2 was operated in Modes 1 and 2 with less than three operable chan-nels of the Overpower AT Reactor Trip System. Channels I and IV were inoperable and in a condition which would have resulted in a channel setpoint change which was nonconservative for a main steam line break accident.
Response
1.
Admission or denial of the alleged viointion Duke power Company agrees that the jumpers found missing in the lead Ian l
(NLL) card of the OPAT circuitry prevented channels A and D from being able to perform their design function when Tava is decreasing. The OPAT circuit is the primar break (0.5 ft{ reactor trip in the event of an intermediate stsam lino l
n
- 1 f t ) at power, and in this typo event. Tavg would be decreasing.
l
. 2.
The reasons for the violations if admitted:
A " low-limiting" jumper (called a "JA" jumper) was not inst.alled on the process control Icad lag (NLL) cards for the Unit 2 channels A and D OPAT circuits. With this jumper missing, channels A and D OPAT circuits were unable to perform their design function in the event of an inter-mediate size steam line break.
On December 1, 1980, protection cabinets were tested and verified correct by site Westinghouse representatives prior to turnover to Duke Steam Production. On January 14, 1981, NLL cards for OPAT were bench tested per a generic procedure that tests fuactions of the circuit board. The last circuit function tested is the negative response, which requires "JA" jumper removal. The last step of this procedure is to reinstall the required jumpers.
The test did not specifically require reinstalling the "JA" jumpers.
It is believed that the two missing jumpers on channels A and D vere not reinstalled af ter this testing because these jumpers were not considered to be required. On January 12, 1983 loop calibration was performed using the "AT/Tavg Protection Calibration" Procedure. Static and increasing Tavg input signals were used in the test, however, a decreasing Tavg condition was not included in the test. A preoperational test proced-ure used on February 11. 1983 verified all card settings, jumper placement (except "JA"), and circuit card outputs (using increasing Tavg only).
Root cause - vendor drawings and documentation give no explicit guidance concerning "JA" jumper for the OPAT application.
Contributing factors -
the OPAT circuit is a unique use of the jumper, other applications of unipolar cards utilize a hard-wired diode which is sufficient in all other applications. Procedural inadequacy associated with circuit card setup and loop calibration.
(Reference Response to Violation 50-370/
84-35-01 and LER 370/84-30 for further details.)
3.
Corrective steps which have been taken and the results achieved:
The JA jumpers were installed in Loop A and D OPAT circuits for Unit 2 immediately af ter discovery of their omission was made (November 26, 1984), and the OPAT circuits were tested to verify the OPAT setpoint responded correctly to a decreasing Tavg ) input.
The other OPAT circuits (channels B and C and the Unit 1 channels were checked to ensure those circuits included the "JA" jumpers. Appropriate procedures were revined.
(Reference Response to Violation 50-370/84-35-01 for further details /
actions.)
4.
Corrective steps which will be taken to avoid further violations:
Procedures for the 7300 type equipment stato npocifically which jumpers are required for the loop application of any card.
Prints for the OPAT circuits changed to show the requirement of a JA jumper on the lead-lag card for the OPAT appilcation.
(Reference Honponse to Violation 50-370/
84-35-01 for further details / actions.)
1 5-5.
Date when full compliance will be achieved:
The jumpers for A and D loops OPAT circuits were installed on November 26, 1984 and all other Unit 2 and Unit I circuits were verified to have the JA jumper as required on this same date.
l l
Compliance fulfilled on November 26. 1984.
l The station was in full compliance with technical specification require-ments in this area on November 26, 1984.
l P
l I
~
Violation: 50-370/84-35-03, Severity Level IV (Supplement I):
Technical Specification 6.8.1 requires that current written approved proced-ures be established, implemented, and maintained covering the activities referenced in Appendix A of Regulatory Guide 1.33 Revision 2. February 1978 which include recovery from Reactor Trip.
Station Directive 3.1.10 requires that malfunctions or failures in equipment or components subject to Technical Specification LCO requirements be evaluated and corrected as required prior to restart. It further requires in Enclosure 4.1 that a review of safety l
systems, including the Reactor Protection System, be performed to identify l
other than expected performance, and also that abnormal behavior be evaluated l
and resolved prior to restart.
Contrary to the above, the post trip review preceding Unit 2 reactor startup of November 25, 1984, was deficient in that it did not evaluate and resolve the abnormal response noted on Channels I and IV of the Overpower AT Reactor Trip System.
Re sponse :
1.
i Admission or denial of the alleged violation:
Duke Power Company agreca that the post trip review did not evaluate f
and resolve the meaning of the observed abnormal response of Channels I and IV of the OPAT signal prior to restart.
Ilowever, the post trip review was performed in accordance with the intended scope and depth described in the station directive. The problem with the OPAT response was not germain to the cause of the reactor trip under review, the OPAT protection function was not actuated in the trip sequence, and the attention paid to the OPAT signals was appropriate for the event circumstances. An error in judgment occurred in that the true cause of the spikes was not immediately recog-nized and their significance not resolved prior to restart.
2.
Reasons for the violations, if admitted:
The reactor trip investigation in question was conducted for the Unit 2 reactor trip on November 24, 1984; apparently caused by an OTAT trip signal while one channel of the Power Range Nucicar Instrumentation System was inoperable. The events which relate to the alleged viola-tions are detailed in LER 370/84-30 and LER 370/84-31.
The investigation was conducted to determine the root cause of the trip, i.e., what caused an OTAT trip signal, and whether those safety systems which were challenged or operated, did so properly.
Incidental to tho investigation, a graph of the OPAT signal was made to see if there was any indication of an input malfunction from one of the signals common to both OPAT and OTAT; there wasn't.
The investigator noted that after the trip, two of the OPAT signals showed a "small" spike and suggested i
l
- 7. -
it be investigated later. It was evaluated as an item to be investigated later for the following reasons:
(A) The spikes occurred after the trip, when most signals vary quite widely.
(B) The profile of the spikes were very similar to those fre-quently seen on instrument channels after a trip, due to voltage spikes on the power distribution system; which are caused by a slow reaction time on the main generator exciter.
(C) The instantaneous value of the OPAT signal is calculated by an elaborate formula, is a dynamic signal, and is not rou-tinely evaluated as part of a trip investigation because of the complexity in doing so and the fact that not all of the parameters necessary for the evaluation are recorded. A computer simulation recreating all inputs and calculations would be needed to fully evaluate signal response.
As mentioned earlier, the Station Directive is oriented toward evaluating what caused the trip, and verifying that the safety systems which operated or should have operated, did so properly. The OPAT signal was not the cause of the trip, and had no affect on the operation of any of the actu-ated safety systems. Beyond that, the directive clearly implies that an abnormal response be recognized as an abnormality which would affect safety. The OPAT spike appeared initially to be a " normal" signal tran-sient af ter the trip, and was noted for further investigation only because two of the channels didn't spike.
It was thought that such an investiga-tion might help determine what could be done about damping the effects of the voltage spikes after trips.
As described in the station directive, the reactor trip investigation process continues beyond the post trip review.
It was and is the intent of this program to fully investigate the particulars directly causing a reactor trip and the response of systems /equiprent directly impacted by the trip during the post trip review.
It is not intended that ancillary occurrences be fully investiaged prior to restart. Rather, it is intended that unexpected behavior of this type be noted and investigated in the follow up phases of the trip investigation process. This is exactly what happened during the event in question and which lead to the discovery of the hardware problem. When viewed in this full and proper perspective, this event demonstrates strength of the program.
3.
Corrective steps which have been taken and the results achieved:
1he immediate steps taken and the resulta achieved are outlined in detail in the referenced LERs, with relation to further investigation and correc-tion of the OPAT circuit problems. The incident and its ramifications were reviewed in detail with the designated trip investigators.
.. 4.
Corrective steps which will be taken to avoid further violations:
)
i Several notes have been added to the Mini-Trip Report to preclude further such occurrences. These include: require evaluation of OPAT and OTAT signal profiles (to the extent possibic), and notes to emphasize the need to investigate safety related abnormalities prior to restart. Discussions were held with all the investigators to ensure an understanding of the principles involved, and the expected responses of OPAT and OTAT were clearly understood.
The trip investigation program is not static but is subject to continuous review and improvement as prompted by operating experience. Actions taken in response to this event have further strengthened an already effective program.
l S. -Date when full compliance will be achieved:
The station was in full compliance with Technical Specification requirements in this area upon completion of actions on March 20, 1985.
l l
l l
l l
q
.