ML19317G836
| ML19317G836 | |
| Person / Time | |
|---|---|
| Site: | Oconee, Rancho Seco  |
| Issue date: | 02/21/1974 |
| From: | Mallay J BABCOCK & WILCOX CO. |
| To: | Schwencer A US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8004010663 | |
| Download: ML19317G836 (4) | |
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February 21, 1974
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Dear Mr. Schwencer:
B&W has completed its evaluation of the effect of the modified standard used for th2 specific heat of UO2 in certain of its transient analyses.
Each B&U customer has been advised of these results.
The pertinent conclusions are succa-rized below.
The new specific heat curve is attached.
All transients normally considered in the SAR have been evaluated.
The slower transients were not affected.
For the rod ejection accident the maxinua cladding temperature decreased by less than 100F and the uaximum fuel tencerature decreased by less than 300F.
For the locked rotor, accident the ua::imum cladding tc,:perature increased by less than 15F and the DNBR results were unchanged.
The four-oump coastdown was not affected.
The reactor building pressure calculation is not altered.
It is therafare concluded that no SAR modifications for this class of transients are required because the results show either an insignificant dif-ference or more conservative results for the old value of specific heat.
The only measurable et'fect of the revision was in the ECCS analysis.
This reanalysis resulted in a lowering of some portions of the allowable linear heat rate by up to 0.65 kW/ft.
This LOCA-derived curve decernines the allowable linear heat rate as a function of elevatica in the core for which the Interim Acceptance Criteria are cet.
Revised limits were determined by repeating the Oconee 2 calculations.
The revised LOCA limit curve for Oconee 2 is attachad.
It is recogniced that the shape of this revised curve does not necessarily reflect the trend of physical reality.
One expects to obtain no inflection points.
The result, however, la due to the application of the overly conservative and arbitrary Interic Accep-tance Criteria.
This ano:naly occurs in the reflooding portion of the calculation, which is being revised in accordance uith the new ECCS rule.
The maxima value by which this curve changed from the previous curve is 0.% kW/ft, which occurs at the s i :-f oo t e:evation.
Tnis is due to a pc.L cladding rature en rerence of 153r Anals,i_ et the F.si, -ba :i r. Em:A %r th.
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A. Schw.wesir Page T:o U.S. Atoaic Ecerg e Cor::in_sion February 21, 1974 Analysi:.: ef Oconee 1 and 2 operating cargins with respect to the revised I.OCA liuit curve was performed based on th2 pirocedures discussed in EAli-10073,
" Operational Parameters for Bdl Rodded Plants" (PRO:2RIEIr These result..: show tha'. t.he revised limit could have been vi.olated only at ir EOL together ui: h th. situltaneous existence of several " worst case" uncert anties and flux peaking.
These units were naver operated at rated power "at or near BOL," and it is doubtful they ever achieved the other required conditions.
With regard to Oconee 1, the revised tech specs presently under consideration by the AEC were evaluated against the revised LOCA limit.
This evaluation took into account the proposed design limits, the procedures of EA'i-10073, and 92 EFPD of burnup.
The results verified the acceptability of the new tech specs.
To assure operation of Oconee 2 and 3, TMI-1, and A';0 within the revised LOCA limit and to core accura ely reflect the operating experience of Oconee 1 and 2, revised tech specs will be submitted to the respective utilities during March 1974.
An analysis for all other B&W plants including the revised specific heat curve is being cade as part of the LOCA evaluation under the new ECCS criteria.
These results will be reflected in new tech spec limits prior to rated pow:.:r operation on these units.
Very truly yours, BABCOCK & WILCOX COMI%NY Nuclear Power Generation 0 -+,# 1-4/6, James F. Mallay Manager, Licensing JFM/db Attach.
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Mr. T. M. Novak
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D*.' to a t aome ry THIS DOCUMENT CONTAINS Jill!.4 :M i. l la n ci:1, m,c POOR QUALITY PAGES
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