ML20096D417
| ML20096D417 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 05/11/1992 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML20096D413 | List: |
| References | |
| NUDOCS 9205180031 | |
| Download: ML20096D417 (4) | |
Text
_. _ _
t Table 6.5.1 RACK MATERIAL DATA (200*F)
Young's Yield Ultimate Modulus Strength Strength Material E (psi)
Sy (psi)
Su (Psi)
SA-240,304L 27.6 x 106 25,000 71,000 (modified)*
Section III Table Table Table Reference I-6.0 I-2.2 I-3.2 SUPPORT MATERIAL DATA (200*F)
Young's Yield Ultimate Modulus Strength Strength Material d (pai)
Sy.(psi)
Su (psi) l 1
SA-240,
- 27. 6 x 10 '
25,000-71,000 Type 304L t
(modified)*
(upper part of support feet) l i
2 SA-564-630 27.6 x 106.
106,300 140,000 (lower part of support feet; I
age hardened at l
1100'F)
-Dual certified to have chemical composition.of 304L material and physical properties of 304 material.
9205180031 920511 POR ADOCK 05000327 P
PDR 6 - -
- ~,-.- - - -.. -
.. ~
i 7.3 Local Bucklina of Fuel Cell Walls This subsection and subsection 7.5 present details on the secondary stresses produced by buckling-and by temperature effects.
The allowable-local buckling stresses in the fuel cell walls are obtained by using classical plate buckling analysis.
The following formula for the critical stress has been used based on a width of cell "b" [7.3.1):
2 n
Et2 Ocr "
12 b2 (1 - p )
2 o
is the limiting vertical compressive stress in the tube, E =
cr 27.6 x 106 pai, p = 0.3, (Poison's ratio),
t=
060" (away from a pedestal), b = 8.75". The factor is suggested in (Ref. 7.3.1) to be 4.0 for a long panel. Near a pedestal, additional cel) wall 4
strength is provided by added strip material which increases the effective thickness of the region prone to buckling to.1045" in the highly loaded region.
For the given data, e
i ccr = 14232 psi f
It should be noted that this stability calculation is based on the applied stress being uniform along the entire _. length of the cell wall.
In the actual-fuel rack, the compressive stress comes from consideration of overall bending of the ' rack structures during~a-seismic event and _ as s uc.h is negligible at the rack top and maximum at the rack bottom.
It is-conservative to apply the above equation to the rac E cell-wall -if we compare a with the-maximum cr compressive stress anywhere in the.-cell wall._As shown in Section 6, the local buckling str_ess-limit is not-violated anywhere in the body of the rack modules. The' maximum compressive stress in the 7-3 W
g*
%---cr>------.
e-9yq.*p4--
y.,..,,
,.,.b,4.
.c._-
v r. -. -
.e g
mi y
g,pg g
e eg-y
-.eqe
~.
~
l outermost cell is obtained by multiplying the limiting value of the strese factor R6 (for the cell cross-section just above the baseplate) by the allowable stress.
Thus, from Table 6.7.2, o=
R6 x allowable stress
.333 x 25000 8325 psi under faulted
=
=
conditions.
7.4 Analysis of the ImpqgLShield for Cask A,1 To maximize the storage capacity of the spent fuel pool, a spent-fuel stcrage isek containing 225 cells (15x15 cells) is proposed to be installed in the 12'x12' cask loading area of the cask pit of the sequoyah spent fuel storage pool. After installation of the rack in the cask _ pit, the pit will be equipped with a removable impact shield (SA-36 material) to prevent accidental dropping of any object on the fuel rack.
The proposed impact shield la shown in Figure 2.4.16.
It consist.9 of panel coverplates attached to a frame made of wide flange beams. This shield is designed to withstand a total load of 288,000 lbs. uniformly applied on the whole shield, or a total load of 70,000 lbs. uniformly applied on one of the panel plates.
The panel plate thickness is detecrmined by a limit load analysis, and the dimensions - of the wide flange beams are chosen so that the maximum stresses in the frame for the postulated load cases are within the corresponding allowables.
l The AUSYS finite element program is used to perform the frame stress analysis. The results are summari::ed below:
(1)
Panel plate can resist a uniform' load of 70,000 lbs, on one panel or a concentrated load of 7952 lbs. applied at any point without sustaining a plastic collapse.
-(2)
Maximum direct plus bending stress in the frame beams is 51961 psi, which is below 90%~~of the ultimate material-strength.
Maximum average shear stress is 2850 psi, which is less than the postulated-allowable (36,000 psi),
(3)
Maximum average compression stress on_ concrete wall at the bearing locations is 329 psi, which is considerably _
lower than the allowable (2975 psi).
l 7-4 L
~. -
r 5
Therefore, we obtain an estimate of maximum weld shear stress in an isolsted hot cell as Imax = 15515 psi l
4 Since this is a secondary thermal stress, it is appropriate to compare this to the allowable weld shear stress for a fculted-event r <.42Su 29820 psi.
Ir. the fuel rack, this maximum
=
stress occurs near the top of the rack and does not interact with any other critical stress.
7.6 References for Section 7 (7.1.1)
TVA Specification 3.94-3QNP-90, Revision 1,
- p. 42.
[7.2.1]
TVA Sequoyah Nuclear Plant Updated Final Safety Analysis Report", April, 1991_ Section 9.1.
(7.3.1)
" Strength of Materials", S.P. Timoshenko, 3rd Edition, Part II, pp 194-197 (1956).-
{7.5.1)
" Seismic Analysis of High Density Fuel Racks, Part III-Structural Design Calculationn
-Theory", -HI-89330,-
Revis 'on 1, 1989.
l 7-6
.__.i.