ML19319C403
| ML19319C403 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/13/1978 |
| From: | Ross D Office of Nuclear Reactor Regulation |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8002140785 | |
| Download: ML19319C403 (4) | |
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, $ h r's d db O Q JUN 1 3 193 MEMORANDUM FOR:
D. B. Vassallo, Assistant Director for Light Water Reactors DP" FROM:
D. F. Ross, Jr., Assistant Director for Reactor Safety, DSS
SUBJECT:
SAFETY EVAll'ATICH OF PROPOSED C!MGE TO THE "DNBR MARGI!!"
TECHNICAL SPECIFICATI0!! FOR DAVIS-BESSE UNIT 1 Docket Mo.piQqe, Unit 1 Plant ? lame-LicensingSh<59-316s e.
GL Responsible Branch and Pro.iect Manager: LHR-1, L. Encle Systems Safety Branch Involved: Analysis Branch Description of Review: Audit Peview Review Status: Reviev of P,io$ sed Change Cc plete The purpose of this nemorandum is to transsit the results of cur safety evaluation of the proposed chance to the "DNBR vargin" Technical Specification of for Davis-Besse Unit 1.
The pronosed changed involved balancing the Fuel Rod Ecwing Penalty of 11.2% by taking: a 15 DNBR credit for the Flow Area Reduction Factor (as described in Section 4.4 of the Davis-Besse Unit 1 FSAR); a 1.11% credit for the DNBR Pcwer Spike Factor (as described in Tccical Report BAW-la01); and a 9.8%
DNBR credit for the effects of increasing recuired reactor coolant flow by 5%. The staff has reviewed each of these credits and finds then acceptable provided that the Technical Scecification on DimR Margin adequately reflect hhe credit t". ken for the increased reactor coolant ficw rate.
In addition, the Technical Soecification must be nodified to provide an allowance of 2.5! for flow reasurenent uncer-tainty in determining the ninimum reactor coolant flow rate to be compared to the Technical Specification limit. A copy of the Table 3.2-1 of the Davis-Besse Unit 1 Technical Specifications, with the staff required modification, is attached. Infomation to support the 2.5% reasurec'ent uncertainty is provided in letter and attachment, Lowell E. Rce to John F. Stolz, Serial No. 436, May 26,1978. To obtain the 2.5% uncertainty (2.2". claimed), the staff increased the df values for reactor coolant pressure uncertainty and reactor coolant i
flow P uncertainty to i1% and 12", respectively. The remaining uncertainties in the May 26 letter are acceptable to the staff.
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~ JtJN 13 1978 With the nodified Technical Specification the staff finds that the treatment of additional DNBR margin, as required for the effects of
}j fuel rod bowing, is acceptable.
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Originaf afaneif W+JY' J
f L Lnaam L
D. F. Rosse Jr., Assistant Director for Reactor Safety Division of Systems Safety cc:
S. Hanauer R. Mattson F. Schroeder R. Boyd J. Stolz L. Engle Z. Rosztoczy L. Phillips W. Hod 9es G. Holahan
Contact:
M. W. Hodges, NRR, X27588 DISTRIBUTION:
Central File DSS:AB Reading File b
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DS[AB, JSS: AD/RS
MWHodges:jb LEPhillip's p_.ZRR'o's z'toczy DERoss% df.
6/~7/78 6//A /78 6/p./78 6/zj/78 NRC FORM 318 (946) NRCM 0240 l'r u. e. sovemuassar comrime orricas este - ese eaa
TABLE 3.2-1 DNB MARGIN 1
LIMITS Four Reactor Three Reactor One Reactor Coolant Pumps Coolant Pumps Coolant Pump S
Parameter Operating Operating Ooerating in Each Loop Reactor Coolant flot Leg ~
II)
Temperature T F
< 611.1
< 611.l
< 611.1 "m
g m
> 2062.7
> 2058.7(l)
> 2091.4 Reactor Coolant Pressure, psig.(2)
Reactor Coolant Flow Rate, gpm(3)
> 178,8d0
> 283,820
> 186,860
) Applicable to the loop with 2 Reactor Coolant Pumps Operating
. ;mit not applicable during either a TilERMAL POWER ramp increase in excess of 5% of 1ATED TilERMAL POWER per minute or a TilERMAL POWER step increase of greater than 10%
af 1ATED TilERMAL POWER.
'- These flows include a flow rate uncertainty of 2.5%.
REFEREriCES (1) Letter and Attachment, Lowell E. Roe to John F. Stolz, Serial No. 436, May 26, 1978.
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