Design and Stress Analysis of Extraterrestrial ... - The Black Vault

"Thermal stresses are the main factor to keep in mind when
designing a fuel element for a reactor. This .s easy to show if we
express the temperature of fuel element through the heat-release
function qv, called the three-dimensional state of thermal stress:
t =t,., i. At tM,,• o14.I-..•"UJ
qv"2 E \-•
If a = 0, then
Ea
Af
•t•I .-. 4 L\
I r
_Ea tI r 1
Ea 2
(2.25)
In the temperature range 50-600 0 C the quantity Ea/(l - i) for
uranium, for example, has virtually a constant value:
S0,35 daN /11.112 TC4.
Figure 2.18 shows the stress distribution in the core o1' a
uranium heat-releasing element with a temperature difference of
At = 1. Circular and axial stresses have the highest value. On the
surface of the core both of these stresses are maximum and equal to
EI
.'.,X , Ea -- A(2.26)
These formulas are useful for evaluating the correctness of the fuel
element core dimensions.
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