ML20097D700
| ML20097D700 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 06/02/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20097D689 | List: |
| References | |
| NUDOCS 9206110085 | |
| Download: ML20097D700 (4) | |
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UNITED STATES 3
<.i NUCLEAR REGULATORY COMMISSION v/ASHINoToN. D.C. 20665
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MffJY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REL ATED TO AMENDMENT NOS. 37 AND 28 TO FACILITY OPERATING LICENSE'NOS. NPF-76 AND NPF-80 EQ"STON LIGHTING & POWER COMPANY CITY PUBLIC SERVICE BOARD OF SAN ANTONIO CENTRAL POWER AND LIGHT COMPANY CITY OF AUSTIN. TEXAS QOCKET N05. 50-498 AND 50-499 SOUTH TEXAS PROJECT. JNITS 1 AND 2
1.0 INTRODUCTION
By application dated May 20, 1992, Houston lighting & Power Company, et. al.,
(the licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License Nos. NPF-76 and NPF-80) for the South Texas Project, bnits 1 and 2.
The proposed changes would add a footnote to Note 14 of Tabic 4.3-1 which states that the complete verification of the operability of the shunt trip relay circuitry shall be implemented for each unit prior to the affected unit's startup from the first planned or unplanned shutdown occurring after May 19, 1992. The change was required due to the discovery that the existing surveillance procedure does not adequately verify the operability of the shunt trip contcets associated with the manual reactor trip function. However, since the surveillance procedure can be performed only during shutdown conditions, it was requested that the amendment allow continued operation of each unit until the next planned or unplanned shutdown.
2.0 EVALUATION.
Le design of the South Texas Project manual t.ip function includes both undervoltage and shunt trip actuating devices te provide redundant mechanisms-to open the reactor trip breakers. The shunt trip contacts which result in energizing the snunt trip coil and opening of the reactor trip breaker include those closed by the reactor trip and safety injection handswitches and an additional contact which closes when the auto shunt trip relay "STA" is de-energized by the opening of the undervoltage contacts. The existing surveillance procedure utilized at the South Texas Project included the g
measurement of voltage across the shunt trip coil but did not include re-opening of the contact closed by the "STA" relay. With the "STA" contact closed, it was not possible to verify that the c:ntacts associated with tha handswitches had also closed and therefore the procedure failed to adequately.
9206110085 920602 PDR ADOCK 05000498 p
.. verify the shunt trip feature as required by Technical Specification 4.3.1.1.-
This-discrepancy was discovered duirng a biennial review of the surveillance F
' procedure.
o.
The proposed Technical Specification change would allow continued operation of i
each South Texas-Project unit until a-revisedtsurveillance procedure is-performed during the next planned or unplanned shutdown.. The revised-I procedure would individually verify the operability of the minual trip function shunt trip contacts by opening of the "STA" contact. Generic' Letter i
85-09 describes the precautions which are applicable to testing of the manual shur.t trip contacts and which will be incorporated into~ the licensee's revised l
procedure.
The South Texas Project reactor protection. system is highly reliable and it is l
unlikely that a manual' trip:would be required to mitigate an anticipated or-i design basis ~ event.
In addition, although the surveillance procedure has-been f
inccmplete, there is-no reason to believe that any element of the manual trip-function is inoperable.. The manual shunt trip tircuitry tested satisfactorily i
during pre-operational-testir,g for each unit.- Additional: confiance 'is -
i provided by the fact that the: manual trip functions have performed.as expected' when utilized on severa1Loccasions during__ operation. The redundancy of the reactor' trip system also ensures that a feilure of any~ single' manual shunt l
trip contact would not prevent aisuccessQ1 manual trip resulting from the undervoltage relays or manual ~ shunt trip associated with the second manual trip.handswitch.
Based upon-its review, the-staff finds the proposed change to the surveillance requirements for testing of the manual shunt trip. circuitry does not-.have a.
e l-significant safety imput and is therefore-acceptable.
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-3.0 EMERGENCY CIRCUMSTANCES
'In the letter dated May 20, 1992, ; i licensee requested'that this; amendment
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application be treated as ar. emergency because unless approved, the Technical:
Specifications would require a shutdown of-both-units. Operation;from May 19 1992, until the completion of the NRC review cf this proposed-amendment mas covered by a Temporary Waiwer of Compliance.
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Regarding the timeliness-of the licensee's. submittal, the: discrepancy:between 1
the Technical. Specification-surveillance-requirements. and the= existing--
surveillance procedure was determined to render the manual trip function
. inoperable on May?19.-1992. _Upon deterrinir9 that the surveillance: procedure ~_
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was inadequate to satisfy the 7echnical Specifications, the licensee requested l
and-received a_ Temporary Waiver of Compliance and requested.a Technical
-Specification-change on an emergency basis by letter dated May'20,41992.
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, Accordingly, pursuant to 10 CFR 50.91(a)(5), the Comission has determined that there are emergency circumstances warranting prompt approval of the proposed change.
4.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION
DETFRMINATION The Comission's regulations in 10 CFR 50.92 state that the Comission may make a final determination that a license amendment involves no significant hazards considerations if operation of that facility in accordance with the amendment would not:
1.
Involve a significant increase in the probability or consequences of an accident previously evaluated; or 2.
Create the possibility of a new or different kind of accident from any accident previously evaluated; or 3.
Involve a significant reduction in a margin of safety.
Tnis amendment has been evaluated against the standards in 10 CFR 50.92.
It does not involve a significant hazards consideration because:
1.
The change would not involve a significant increase in the probability or consequences of an accident previously evaluated.
Delaying the implementation of the surveillance requirement involves no physical mocification of the facility, nor does it affect any operational parameters.
The accident analyses in Chapter 15 of the Updated Final Safety Antlysis Report (UFSAR) do not take credit for the manual trip function and are therefore not affected by the proposed change. An evaluation of the core damage frequucy contribution from the anticipated transient without scram (ATWS) event determined that the assumed unavailability of the-shunt trip function did-not have a significant impact on the results.
2.
The change would not create the possibility of a new or different ~
kind of accident from any accident previously evaluated.
No physical changes to the plant or changes to operating parameters are proposed. Those accidents which night involve failure of the manual shunt trip function are bounded by those performed to evaluate the failure of the reactor protection system.
3.
The change would not involve a significant reduction in a margin of -
safety.
It is likely that the manual shunt trip function would perform and there is no adverse safety impact involved in delaying the performance of the required surveillance.
In 15e case where the manual shunt trip function is assumed to be inopwble, the calculated change in core damage frequency was not significant.
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5.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Texas State official was notified of the proposed issuance of the amendment. - The State official had lo comments.
6.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defir.ed in 10 CFR i
Part 20. The NRC staff has determined that the-amendment involves no
- significant increase in the amounts, and no significant change in the types, of any ' effluents that may'be released offsite, and that there 'is no signifi: ant increase in individual or cumulative occupational radiation exposure.
The Commission made a final-no significant hazards consideration finding with respect to this amendment. Accordingly, the amendmer,. meets the eligibility criteria for categorical exclusion. set.forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(bj no environmental impact statement or environmental assessment need be prepared in connection with the issuance of 4
the amendment.
5,0 (ONCLUSION The Commission has r.oncluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be' endangered by operation in the proposed manner, (2) such 4
activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inirical-to the common defense and security or to the health and safety of the public.
Principal Contributor: William D. Retiley Date:
June -
1992 l
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