ML20091N466
| ML20091N466 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 01/22/1992 |
| From: | Joshua Wilson TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9201300235 | |
| Download: ML20091N466 (7) | |
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January 22, 1992 U.S. Nuclear Regulatory Congnission ATTN: -Document Control Desk Washington, D.C. 20555 Centlement In the Matter of
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Docket Nos. 50-327
'rrnessee Valley Authority
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50-328 PEQUOYAH NUCLEAR PLANT (SQN) - NRC INSPECTION REPORT NOS. 50-327, a28/91 RESPONSE TO NOTICE OF VIO1.ATION (NOV) 50-327, 328/91-26-01 AND -03 contains TVA's response to Bruce A. Wilson's letter to Dan A. Nauman dated December 43, 1991, which transmitted the subject NOV. The first violation-dealt with failure to take effective and timely corrective action for a previous event concerning loss of the refueling water storage tank icvel transmitters. The second violation involved failure to adequately implement the design control process associated with the installation of a new annunciator system in the main control room. A summary of new commitments contained in this submittal is provided in Enclosure 2.
A typographical error was noted in the citation of the NOV-Example B, Violation 50-327, 328/91-26-03, states, " contrary to the nuove, measures did not provide for verifying the adequacy of the design of the annunciator system modification process from November 4 to November 24, 1991." However, the annunciator system was returned to functional status upon installation of the resistors in the-inputa to the temporary system on November 21, 1991.
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U.S. Nuclear Regulatory Commission Page 2 January 22, 1992 If you have any questions concerning this submittal, please telephone M.'A. Ccoper at (bl5) 843-8924.
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Sincerely, svL IIL. Wilson V
Enclosures cc (Enclosures):-
Mr. D. E. ' LaBarge, Pro ject Manager J.S.-Nuclear Regulatory Commission-
- One White Flint, Nortu 11555 Rockville Pike Rockville, Maryland 20852 NRC-Resident Inspector Sequoyah Nuclear Plant
' 2600 Igou Fetcry Road Soddy sy,_ Tennessee 37379 Mr. B._A. Wilson, Project Chief U.S._ Nuclear Regu'.at.rv ~~"-4.fssion
- Region II_
V., Suite 2900 101 Marietta Street, Atlanta, Georgia 30323 3
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4 ENCLOSURE 1 RESPONSE TO NRC INSPECTION REPORT NOS. 50-327/91-26 AND 50-328/91-26 BRUCE A. WILSON'S LETTER TO DAN A. NAUMAN DATED DECEMBER 23, 1991 Violation 50-327, 328/91-26-01 "A.
10 CFR-50, Appendix B, Criterion 16 requires, in part, that significant conditions adverse to quality are promptly identified and corrected; and, that the corrective actions preclude repetition.
" Contrary to the above, on December 2, 1991, flooding of the Unit 2 refueling water storage tank basin resulted in the failure of level instrumentation for the tank. This event was similar to an event that occurred in 1989 on the Unit I refueling water storage tank and corrective actions for that event were inadequate to prevent the December 2 event.
"This is a Severity Level IV violation (Sapplement I)."
l-Admission-l-
TVA admits the violation.
Reason for the Violation The-root cause of the event resulting in this violation is considered to be ineffective administrative controls to compensate for a design deficiency.
Corrective actions taken as a result of the 19;9 ficoding event included clarification of the established administrative controls by providing further guidance for shiftly checks of the basin. The assistant unit ot erator (AUO) round sheets were revised to include this clarification.
Performance of a shiftly' check of the water level in the basin was expected to preclude the repetition of the 1989 event.
During the evening shift of December 2, 1991, the shiftly check.of the basin was not performed. The AUO overlooked checking the basin during his rounds. -He did not return ;o the basin to perform the check when he realized it was overlooked. Addit ionally, he did not-inform his supervisor of the missed check and did not'take his round sheets to the ain
,l control room (MCC)-for his supervisor's review.
i Evaluation following the event resulting in this violation has-determined that shif tly checks of ' the basin may not-be adequate during heavy rain conditions
'to ensure that the level does not reach the cabinets.
If one AUO checks the L,
basin at the first of the shift and the next AUO checks the basin at the last of the shift, rain data indicater. that the level in tbo basin could reach the cabinets ~'in less than-the 16-hour period between checks.
However, if shiftly
- chears are' interpreted to require an-eight-hour f requency, maximum probable prn;ipitation data, as described in the Final Safety Analysis Report (FSAR),
supports shiftly checksias an adequate-frequency. The AUO's failure te
.ck E
the basin, as required, precluded the possibility of detection and miti ;c i an i
l of.the high water level in the refueling. water stortge tank (RWST) bas;n
.f he had checked the basin at the end of his shift, the event may still hcee occurred because of the rain experienced during this timef rame.
Ge erating a plant modification study package addressing feasible options to e.'
nate flooding in the RWST' basins was also included as corrective action
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for the=1989' event. The_ study perf ormed reconnended the installation of a rain shleid to eliminate flooding in the RWST basins.
Follow-up action on this recommendation has not yet been implemented.
Ilowever, administrative controls.to compensate for the design deficiency were expected to preclude the event resulting in this violation.
Corrective Steps That llave Been Tqken and_ Results Achieved The RWST basins were pumped out and the level transmitters and terminal strips were dried. The proper operation of the transmitters was verified, and they
-were returned to service.
Standing orders were issue. on an interim basis untit formal p*ncedural requirements could be implemented to require a check of the RWST basin every two hours during periods of rain.
Additionally, the requirement for the assistant shift operations supervisor (ASOS) to review AUO round sheets on a shiftly basis was reinforced.
-Corrective _ Steps That Will Be Taken to Avoid Fcrther Violations o
Ex eted actions-concerning the RWST basin level checks will be formally r
proceduralized to strengthen the administrative controla.
The performance et the evening shift AUO-on December 2, 1991, did not meet expectations. Additionally, ADO performance improvements have been recognized as being behind the improvements of the control room staff. An AU0 improvement plan is-being developed to generically upgrade the performance of AU0s. - Implementation of this plan will ensure standards of performance are clearly ccnveyed, demonstrated, and enforced.
Date When Full Compilance~Will Be Achieved Full compliance wasfachieved on December 2, 1991, at 0334 Eastern standard time when'the level transmitters were returned to operable statua.
Violation 50-327,132d/91-26-03 l
l "B.10 CFR 50, Appendix B Criterion 3 requires, in part, that measures st ill be established for'the selection and si tow for suitability of application cof materials, parts, equipment, and processes which.are essential to the functions of the components involving plant safety; and, that these measures shall also provide for verifying _the adequacy of the design.
" Contrary:to-the above, measures did not provide for verifying the adequacy of the design of the annunciator system modification process from November 4_to November 24,-1991.
During this time period, a temporary annunciator system, which was providing annunciation of important safety-related parameters on Unit 1, was determined to have up to 20 inoperable alarm points due to_an inadequate evaluation which had been performed on the suitability of alternating current interfaces between the existing alarm outputs and the installed temporary system.
"This is a Severity Level IV violation (Supplement I)."
t.
Admission TVA admits the violation.
Reason for the Violatien The interface between plant equipment and the new annunciator system was not adequately addressed. The system was designed to utilize inputs from dry contacts..i.e., either off or on.
The plant configuration, however, has several inputs to the system from The Foxboro Company bistables containing triacs, which have significant leakage currents. A contract design firm designed the now annunciator system for TVA. 1The contractor's personnel stated that they intended for the interfaces with_ plant equipment to be addressed by the equipment vendor.
In the procurement specification for the annunciator system, the intent for the vendor to perform this function was not citarly delineated. Additionally, information necessary to perform this function vos.not provided in the specification.
-A meeting was held at the vendor's reques~ to outain additional data regarding the locations, dimensions, interface requirements, etc., for installation of the new~ annunciator system.
Infcrmation regarding the triac inputs from the Foxboro bistables was not conveyed to the vendor during this meeting. The vendor designed-and manufactured the SQN system based on the assumption that the inputs were from dry contacts.
The initiating event for this problem was the flawed procurement specification; the intent for the vendor to address interfaces with plant equipment was not clearly delineated. The contractor's design progressed under the assumption that the vendor would address system interface, and the vendor'a_ design: progressed under the assumption that the inputs were f rom dry contacts. These two disconnects also led,to reviews and tests not identifying the interface problem. The cause_of the flawed procurement specification is considered <0 be inadequate-management oversight of the development of the specification.
Corr'etive Steps That Have Been Taken end Results Achieved I
Upon discovery of the problem, edditional operators were posted on Unit 1 to increase-monitoring of operational parameters. Revistors were added to the relay card-input circuits to ensure impedance values were adequate for proper system operation on November 21, 1991.
Fotced~ air circulation was added in the' cabinets -containing the resistors to dissipate the heat generated.
Corrective Steps That ~ Will Be Taken to Avoid Further Violations The procedure governing development of_ procurement specifications will be revised to ensure that inte.rf ace evaluation responsibilities are clearly
-delineated in future specifications. Review of this event, as-a case study, will.be conducted with management personnel of the contract design' firm currently utilized at SQN; this reviev will convey expectations relative to management oversight of work produced to ensure deliverables comply with requirements.
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Date When Full Compliance Will Be Achieved Full compliance was achieved on Novemb"r 21, 1991, when resistors were added to the temporary annunciator system inputs.
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.e ENCLOSURE 2 List of Commitments Violation 50-327. 328/91-26-01 Commitments made in response to this notice of violation are tracked under Licensee Event Report 50-328/91008.
328/91-26-03 Vi_olation 50-32,73 1.
The procedure governing development of procurement specifications will be revised to ensure interface evaluation responsibilities are clearly delineated in futtre specifications. This action will be completed by May 4, 1992.
2.
Review of this event, as a case study, will be conducted with management personnel of the contract design firm currently utilized at SQN; this review will convey expectations relative to management oversight of work l
produced to ensure deliverables comply with requirements. This action will be completed by Februaty 21, 1992.
i PLO90204/1628 l'