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Question 3.11: Using the data in Appendix E calculate the microscopic absor......

Using the data in Appendix E calculate the microscopic absorption cross section of water, averaged over a thermal neutron spectrum:

a. at room temperature.
b. at 300 °C, which is a typical operating temperature for a water-cooled reactor.

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The microscopic cross section may be considered 1/v.

a. The value in the appendix is tat room temperature of T_{o}=293.61° K .The value is 0.5896 b

b. Temperature corrections for 1/v cross sections are given by the expression following Eq. (3.59):

\overline{\sigma}_{a T}(T)=\left(T_{o}/T\right)^{1/2}\overline{\sigma}_{a T}(T_{o})

Since 300 °C = 300 + 273 °K = 573 °K

{\bar{\sigma}}_{aT}(573)=\left(293.6/573\right)^{1/2}0.5896=0.422b

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