ML19224A355
| ML19224A355 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 12/15/1978 |
| From: | Silver H, Varga S Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19224A352 | List: |
| References | |
| TASK-TF, TASK-TMR TM-0167, TM-167, NUDOCS 7901020176 | |
| Download: ML19224A355 (3) | |
Text
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[pa arog*g UNITED ST ATES yN
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W ASHINGToN, D. C. 20555 5
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- SAFETY EVALUAT10N BY THE OFFICE UF NUCLEAR REACIOR RLGULAT10N
,SUFFURllNG Af1NulaNI No. 6 TO FACILITY UPERATING LICLNSL h0. UPR-73 METROPOLITAN EDISON COlPANY JERSLY CLNIRAL PUWLR & LIGHT CUf7ANY PLNNSLYVANIA LLLClRIC CUhPANY DOCKET NO. 50-320 THRLE hlLE ISLAND NUCLEAR STATION, UNIT 2 Introduction By letter dated Deceuber 11, 1978 transmitting Technical $pecification Change Request No. 18, as amended by letter dated December 13, 1978 and attachments, Metropolitan Edison Company (Met Ed) requested amendment of Appendix A to facility Operating License No. DPR-73 for Three Mile Island Nuclear Station, Unit 2 (TMI-2).
The requested change would amend the Technical Specifications to allow plant operation at certain reduced power levels with specified reduced reactor coolant system (RCS) flow.
Discussion Currently, the Thl-2 Technical Specifications require that whenever four Reactor Coolant Punps are operating, a minimua RCS f ow of 3/7,000 gpm be maintained, regardless of the reactor power level.
This restriction is made in order to maintain an acceptable DNBR at 100% power level.
For lower reactor power levels, the same degree of conservatism can be maintained with lower RCS flow rates.
Therefore, the 377,000 gpm limitation is overly conservative for reactor pcwer levels lower than 100%.
The changes proposed for the TMI-2 Technical Specifications allow a similar degree of conservatism which has been used in determining the minunun Rr5 flow rate associated with 100% reactor power, to be applied in deterinining the minimum RCS flow rates associated with lower reactor power levels.
Analyses have shown that the one pump coastdown is the most limiting DNBR transient and is the one which establishes acceptable initial power and flow conditions. Reanalysis by the NSSS supplier (Babcock & Wilcox) have shown that at reduced flow rates, an acceptably conservative margin to liuiting DNBR may be retdined by a reduction in core thermal power.
The applicant states that the proposed flow-power level values conservatively bound the B&W analyses for these lower flow conditions with a predicted minimua DNBR of 1.42 for the most limiting of the power flow combinations listed.
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_2 The TMI-2 ECCS Analyses were performed assuming aa RCS flow rate of 370,496 With the proposed changes, if the RCS flow rate is below the level at gpa.
which the transient and accident analyses were performed, reactor power will be reduced in the same manner, and to the same level as currently required by the TMI-2 Technical Specifications.
Various other safety analyses were perf ormed on an RCS flow rote of 2;9,600 gpa and are thus conservatively bounded by the 370,496 gpu limit listed above.
Thus, the proposed changes in the Technical Specification neither invalidate the Saf ety Analyses which have been performed f or TMI-2, nor significantly reduce the degree of conservatism used in determining the minimum flow needed for a given reactor power level. In dddition, the propnsed requirenents of the Technical Specifications assure that an ecceptable DNBR is maintained.
The licensee has also specified lower overpower trip rettings corresponding to the lower flow / power conditions proposed, and has described administcative controls to ensure maintenance of appropriate settings.
Evaluation We have reviewed the proposed flow rates corresponding to the power levels of concern, and the results of the B&W reanalyses, and find that since the reported DNBR value of 1.42 neets the DNBR criterion of'l.41 in BAW-2 for cycle 1 accounting for rod bow ef fects, they are theref ore acceptable.
We also find that the minimum permissible flow rate at 98% power is the same as that at which the LOCA analysis was perforn:ed and that the LOCA analyses dre not impacted by these changes, and that analyses performed at lower flows are bounded by that flow.
We find that the lower overpower trip settings corresponding to the lower flow / power conditions are appropriate, and that adequate adainistrative procedures have been proposed to assure that these settings will be maintained.
In summary, we have evaluated the proposed changes in Technical Specification Change Request No.18, and having found them acceptable, we conclude that the f acility operating license can be amended by changing the Technical Specifica-tions as shown in the attachment to this license amendment.
We have further concluoed, based on the considerations discussed above, that:
(1) because the amendment does not involve a significant increase in the probability or consequences'of accidents previously considered and does not involve a significant cecrease in a safety margin, the amendment does not involve a significant hazards condsideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Comaission's regulations and the issuance of this amendment will not be inimical to the common defense and security or the health and safety of the public.
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.l, Environmental Consideration We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Itaving made this determination, we have further concluded that the amendment involves an action which is insignificant f rom the standpoint of environmental impact and, pursuant to 10 CFR $51.5(d)(4), that an environmental impact statement or negative declaration and environroental impact appraisal need not be prepared in connection with the issuance of this amendment.
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lia rl ey ver, Project Manager
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iig Light 'Jater Reactors Branch No. 4 Light Water Reactors Cr nch No. 4 Division of Project Management Division of Project Management December 15, 1978 s
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