ML20008G184

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Forwards Supplemental Response to NRC Concerns Re High Density Fuel Rack Analysis
ML20008G184
Person / Time
Site: Fermi DTE Energy icon.png
Issue date: 06/26/1981
From: Colbert W
DETROIT EDISON CO.
To: Kintner L
Office of Nuclear Reactor Regulation
References
EF2-53811, NUDOCS 8107020411
Download: ML20008G184 (3)


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June 26, 1981

EF2-S3811 l

f Mr. L. L. Kintner Division of Project Manageaient Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Cosranission Washington, D.C. 20555 2

Reference:

Enrico Fermi Aton.ic Powcr Plant Unit NRC Docket No. 50-341 Structural 1;ncincering Branch: sl:Ts Subjcet:

- High Dcusity Pucl Ha g

Dear Mr. Kintner:

To suppicment Detroit Edison's response to the NRC staff concerns, we arc sending the "llighlight'of High Density Rack Analysis Results". This material was discussed with IIafiz and Mr. Rothberg in a confercnge your Dr. Kuo, Dr. call between our Yogi Anand, Abdul Alchalabi and Kris Singh of Joseph Oat Corporation.

l Sincerely, l

7,44.WhLF

  • Colbert William P.

Technical Director i Enrico Fermi 2 i

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HIGLIGHT OF HD RACK ANALYSIS RESULTS EMtICO FERMI PROJECT OAT Jf7023 & Jf2437. __

These are three different rack geometries, labelled as rock types A, 8 &

C respectively. There are 13 andules of rack type A, one each of type B

& C.

The design basis earthquake time history accelerations in three directions were applied on these three geometries. The total structural damning was l assmed to be 45. A 32 degree of freedom three dimensional model was employed -

for perforising the analysis. The coefficient of friction between the rack base and the ground is assumed to be 0.8. Smaller coeffieient of friction were found i tb yield smaller total displacement (rigid body translation and rotation). Some l influential parameters, the inclusion of which would greatly reduce both rack

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total displacement and stress levels, have been disregarded in the analysis; l viz: ,

a. The " plate type" structural flexibility of the floor slate has been disregarded. Irr our experience, inclusion of this flex- '

ibility reduces the stress levels by as much as 30%.

b. The energy dissipation due to rattling of the fuel assemblies i inside the storage locations is entirely neglected. We have found that the stress levels decrease by as much as 251 if only 101 of fluid drag (reported in the literature) is used. The table below gives the maximum rack displacement, and load factors

! for full and empty conditions for the three rack types.

We surmise from the site specific response spectra that the assoc.

iated acceleration time histories will contain approximately 50%

more energy in the rigid range. Since the rack fundamental'fre- l 4

quency is high (over 33 Hz ), it stands to reason that 505 sore ,

energy will annifest in the rack response in the fom of (a) rack .

strain energy (b) loss.due to sliding friction. The latter is  !

known to increase more than linearly with the seismic input intensity.

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Page Two Accordingly, the fonser increases in a less than linear ratio. These con-

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siderations, borne out by numerical experiments on out cruciform construction racks, lead us to project the estimated maximum rack displacements and the corresponding load factors in the manner listed in the table below.

A renalysis is being made to confine these estianted values.

Rack 5 conditima d, ,

Imad f tor Displae===at for Factor ,

Omr h)" Site spec. .or dte n Earthq. M A 0.5n 1.2 1.os 13 r

yell , ,

. A mapey 0.62 1.3 m anell -

s Fall . .534 1.1 .622 1.0 3 hyty .513 18 - -

c. . . . . Fall .71S= 1.5 1,335 . 1.6 C Buyty 427" 9 -

. t Allouable disp 1-c = 1.875" for A and C racks; Et .k 3 is inat=ted.

Tf All - hle Imad factor = 2.0 m

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