ML20037B603
| ML20037B603 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 11/07/1975 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Bolger R COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8010220726 | |
| Download: ML20037B603 (4) | |
Text
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DISTRIBUTION Docket.
-NOV 7 1975
'h7C PDR Local PDR 7 i ct ':2. 5 0 -; t ORB Reading KRGoller TJCarter.
Cc ren.realth Edison Company OELD ATTN:
':r.-R. L. Bolger OISE. (3)
Assistant Vice President DLZiemann Post Office.Dox 767
.PW0'Connor Chicago, Illinois 60690 RMDiggs
-TBAbernathy SVarga.
ACRS (16)
Gentlemen:
DEisenhut We are reviewing your July 31, 1975 subnittal proposing chanres to the Technical Specifications of Dresden Unit 1.
These changes incorporate e erzting lirits based on an energency core cooling systen r.nr. lysis cdel thr.t _ conforns with the requirements of Section 50.46 of 10 CFR Partt50. Ue have determined that the additional information described ~
in the enclosure is necessary to continue our review.
To enable us to naintain our review schedule, please su b it the requested
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infor.ation by November 13, 1975.
Sincerely, Eginal signed by Dennis L. Ziemann Dennis L. Zienann, Chief Operating Reactors Branch #2 Division of Reactor Licensing
Enclosure:
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Commonwealth Edison Company cc w/ enclosure:
John ii. Rowe, Esquire Isham, Lincoln 5 Beale Counselors at Law One First National Plaza-Chicago, Illinois 60670 e
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t.0MMONWEALTli EDISON COMPANY DRESDEN NUCLEAR POWER STATION UNIT 1 DOCKET NO. 50 _10_
REQUEST FOR ADDITIONAL INFORMATION 1.
Describe the correlations and methods used to determine the heat transfer coefficients assumed during each time period shown on Figures D-1 through D-10.
Justify the conservatism of the c.orrelations,and methods for each break size, and specify the differences (if any) in methods used to calculate the coefficients for large and small break models.
2.
Provide a description of any differences between the large break model (LBM) and the small break model (SBM) (if any), plus an indication of which breaks were analyzed with each model, and a justification for the ccnservatism of the model chosen for each break si:c.
3.
It is our position that the Technical Specifications shall include a Limiting Condition for Operation (LCO) which provides assurance that operating conditions will be more conservative than the initial conditions assumed in the Dresden 1 ECCS LOCA analyses.
Non-jet pump BWR ECCS models utilize an empirical correlation to determine the duration of nucleate boiling heat transfer in the early period following the postulated pipe break. This correlation for time to dryout is found to be proportional to the ratio of assembly water volume to power.
Drycut time is a signi-ficant parameter in determining the extent of nuc1cate and tri.nsition boiling heat transfer, and consequently the peak cladding temperature.
An exampic of an acceptabic LCO is in the form:
"During power operation, the assembly average void fraction and assembly average power shall be such that the following relaticnship is satisfied:
(1-VF)
>B PR x FCP khere:
VF = Bundle average void fraction PR =. Assembly radial power factor FCP = Fractional core power (a limiting value of "B" shall be specified for each fuel type in the core relative to 714 MXt)
B = Power-Void Limit Other proposed Technical Specifications, such as MCPR or Power-Flow limits, may also be acceptabla provided that it can be clearly demonstrated that they accomplish the above mentioned objective of assuring that the ECCS model conditions are conservatively applied s
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' 4.
_Specify the spray cooling coefficients assumed. l Provide or reference the' experimental data on which'the coefficients are basec.
The experi-mental data provided or' referenced must be,from 6 x 6 assemblies of-
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the D-1 design, or appropriate quantitative justification must be5 provided justifying use of data derived from other geometries for the
- 6 x 6 D-1_ design.
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5.
Describe -or incorporate by. reference any variance from' the requirements of 10 CFR 50.46 that were assumed in the Dresden 1 ECCS Apendix K " Plant -
As-Is" analysis.
Ip addition. list any systems khich were not.' designed
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as engineered safety systems that are assumed to. function in your analysis to mitigate the consequencesDef a loss of coolant accident.
- This list should include. equipment and systems required to -function in the event of a core spray line break-_without feedwater.'
- 6.
Describe how long_ term cooling will be accomplished after the' hot well condensate supply is exhausted.
7.
Provide a detailed-list of all.information' supplied by Commonwealth ~
Edison to General Electric for use by GE in characterizing-the non-GE fuel.
Include parameters necessary to: calculate _ initial gap conductivity,' fuel densification, clad swelling and rupture, and potential for fuel rod bowing.
Provide a separate, list of any such input needed by GE that 'was not specifically.available, and in each case des ~cribe how.the_needed parameter was conservatively estimated.
8.
Provide the_ application of the GE " submerged valves.in containment" analysis to D-1.
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