ML20090F280

Forwards Addl Info Re Spent Fuel Pool Two Region Rerack Mods,In Response to 840712 Telcon

ML20090F280
Person / Time
Site:	Mcguire, McGuire
Issue date:	07/16/1984
From:	Tucker H DUKE POWER CO.
To:	Adensam E, Harold Denton Office of Nuclear Reactor Regulation
References
TAC-53531, TAC-53532, NUDOCS 8407200223
Download: ML20090F280 (3)

Text

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DuxE POWER GOMPANY P.O. HOx 33:80 CHAMLOTTE. N.o. 28242 HAL H. TUCKER Tet.cronose vu.a reusement (704) 373-4M1

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July 16, 1984 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Ms. E. G. Adensam, Chief Licensing Branch No. 4 Re: McGuire Nuclear Station Docket Nos. 50-369, 50-370

Dear Mr. Denton:

Please find attached additional information concerning the McGuire Nuclear Station spent fuel pool two region rerack modifications. This additional Inforr'ation is provided in response to a telephone conference call held on July 12, 1984 between Duke, Franklin Research Center,and the NRC which concerns the spent fuel rack design and analysis. If there are further questions regarding this matter, please contact us.

Very truly yours, fb . /M //h(/

Hal B. Tucker WHM/rhs cc: Mr. J. P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region il 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 Mr. W. T. Orders Senior Resident inspector McGuire Nuclear Station 00 D 0 N9 P PDR

< DUKE POWER COMPANY McGuira Nuclear Station Spent Fuel Pool Rerack Modifications Additional Information Request 1: With respect to fuel assembly impact damping, was conservatism of the seismic dynamic analysis maintained since the upper bound value (15%) of the impact damping range was used in lieu of the 10% lower bound? .

Response:- In determining the fuel assembly impact damping, B & W performed a series of tests. The upper and lower bounds for the tests are reported as .1462 and .1650 respectively with a median value for all tests of .1565. B & W Topical Report 10133P Rev.1, filed with the NRC on 5/31/79, gives a fuel assembly impact damping value of 16% for a Mark C assembly. The report also notes that B & W Mark C characteristics are similar to the B & W Mark B assembly characteristics which are stored at ficGuire, thus, the results are directly ccmparable. The Applicant maintains that use of a damping value of 15% is appropriate and the conser-vatisms of the analytical results used in the design of the proposed racks are preserved.

Request 2: ' Two horizcntal seismic response spectra were available, of which one was used for time history analysis. It is not clear

' if the spectrum used for the time history analysis provided the most conservatism.

Response: Of the two horizontal seismic response spectra, the E-W spectrum has larger acceleration values than the N-S spectrum in the frequency range of the fuel rack, (4-8 Hz). Thus, the seismic analysis was conservatively performed with the E-W response spectrum, the E-W hydrodynamic mass (maximum hydrodynamic mass),

t and the minimum support pad spacing (N-S in region 2 and E-W in region 1), to obtain the maximum fuel rack response.

Request 3: provide analysis supporting the conclusion regarding the 234-inch fuel assembly accidental drop.

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Respcnse: Analysis has been performed which shows that the 234 inch fuel

, ,' assembly accidental drop satisfies the design criteria of not

, resulting in perforation of the pool liner. In the analysis it is shown that the energy of the falling fuel assembly is satis-

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facto'rily absorbed by the crushing of the fuel rack base plate

, , and the defermation of the lower portion of the fuel assembly i (lower fitting and lower portion of the guide tubes and instru-ment tube). ~The load transmitted to the pool liner is such that the stress developed in the liner does not result in perforation.

It should be noted that the analysis performed is conservative in that the fuel assembly is assumed to be under free fall (water i

resistance within the cell, is neglected), and it is assumed that no energy is dissipated by the breaking of welds which hold the base plate to the rest of the rack.

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i Request 4: Provide the description of the analytic model used for the spent )

i I fuel pool floor in Unit 2.  ;

Response: As stated in section 3.1, paragraph 4, of the license submittal, the Unit 2 pool floor is supported continuously on bedrock. All ,

dead, live and seismic loads are transmitted directly through the floor to the bedrock foundation. In response to an earlier question concerning the model and loading system used in the analysis'of the spent fuel pool floor (reference response to Question no.1, letter dated June 19,1984), reference was made only to the Unit 1 pool floor slab. The Unit 2 pool floor slab l

analysis was not addressed since the Unit 1 pool floor repre-sented the limiting condition.

' Request 5: Provide additional discussion relative to the effect of fuel densification on the seismic response of the Spent Fuel Pool-Floor Slab.

l Response: The McGuire Auxiliary Building is 'a poured in place reinforced l concrete structure as stated in Section 3.8.4.1.1 of the McGuire FSAR. Contained in this building are auxiliary systems, control rooms, and spent fuel pools for both units along with related piping and electrical cables. The mass added as a result of fuel  ;

l densification is negligible compared to the mass of the structures and equipment comprising the Auxiliary Building, thus, the seismic i response spectra applicable to the spent fuel pool' floor slab is not altered. The method of dynamic analysis is described in

, Section 3.7.2.1 of the McGuire FSAR.

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