ML20101G126

Forwards Addl Info in Response to NRC Finding 2-1 Identified in Integrated Design Insp Rept 50-454/83-32 & Rev 3 to Auxiliary Bldg Flood Level Calculations. Flood Level Predictions in Four Zones Reduced

ML20101G126
Person / Time
Site:	Byron
Issue date:	12/14/1984
From:	Tramm T COMMONWEALTH EDISON CO.
To:	Deyoung R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
Shared Package
ML20101G133	List: ML20101G126 ML20101G135
References
9531N, NUDOCS 8412270428
Download: ML20101G126 (2)

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m );one First National Plaza; Chic go. Illinos -

O~ Address Reply to: Post Offics Box )67

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December 114, 1984-r

.Mr. R..C. DeYoung,-Director ~ '

- Office of' Inspection and : Enforcement F~ Washington,?DC 20055

Subject:

Byron Generating Station U' nits.1 and 2 Independent Design' Inspection

, __- , ~NRCEInspection-Report No'.' 50-454/83-32

-t ReferenceL(a): October 19, 1984 letter from T. R.-Tramm C

3 to R. C. DeYoung

Dear:

Mr. DeYoung:-

This letter provides additional information'in response to-the:NRC's' Finding 2-1 which was identified during the Byron

-Integrated Design-Inspection.- Enclosed.is revision 3 of Sargent and.

-Lundy calculation 3C8-1281-001, " Auxiliary Building Flood ~ Level Calculations". Review of-this-calculation should enable the NRC to

the actions taken to address Finding 2-19.

Only minor changes have been.made in revision 3 of this report. The changes are noted by-change bars in the right margin.

Specifically, the flood level predictions in 4 zones have been-

- reduced based on more realistic mdeling'of-~the worst; case breaks or cracks. , ,

'The blowdown condenser rooms-(zones S3-3A and S3-3B)'were

- . originally.modeled with both the normal blowdown path and the

' alternate: blowdown path open. In reality only one path is used and-this-correction led to significantly lower levels. The positive 1 displacement charging pump rooms (zones S3-9A and S3-98) were Loriginally calculated. assuming a break in a location'which would

.a110w backflow'from the-centrifugal charging pumps. This location was determined to be a low stress point where no break postulation

'was required.

The calculations for these areas were refined because the floorislab capability was in question with the original levels due to the-combination of floodiload and equipment loads,1and further

_ ' assessment of the effects of slab failure is more difficult than

- "4 ' refinement of the flood level calculation. With the current calculated flood = levels the floor slabs designs contain adequate

~ margin.-

Please address further questions regarding this matter to p ra m ik "n gg/

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this office.. .

. One signed original .and' fifteen copies of _this letter are

provided for.NRC; review.

Very-truly yours, fik f/W T. R. Tramm Nuclear Licensing Administrator cc:' O. Norkin 9531N P