In a nuclear reactor, the effective cross section for thermal neutrons in uranium is the weighted average of the cross sections for the 235 and 238 isotopes present. The thermal neutron cross section is zero for 238U and 580 barns for 235U. Find the effective cross section for thermal neutrons in a reactor that contains (a) natural uranium and (b) uranium enriched to 2.0% 235U
In a nuclear reactor, the effective cross section for thermal neutrons in uranium is the weighted average of the cross sections for the 235 and 238 isotopes present. The thermal neutron cross section is zero for 238U and 580 barns for 235U. Find the effective cross section for thermal neutrons in a reactor that contains (a) natural uranium and (b) uranium enriched to 2.0% 235U
Part-a
Given:
- Natural abundance of 235U is 99.27%.
- Natural abundance of 238U is 0.73%.
The equation for cross section of thermal neutron by weighing uranium by their natural abundances can be given by,
Substitute the required values in the above equation to obtain the cross section of thermal neutron.
Therefore, the effective cross section for thermal neutrons in a reactor that contains natural uranium is 3.80 barn.
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