Uranium-235 releases an average of 2.5 neutrons per fission,while plutonium-239 releases an average of 2.7 neutrons per fission.Which of these elements might you therefore expect to have the smaller critical mass?
A)plutonium-239
B)uranium-235
C)The number of neutrons per fission will not effect the size of critical mass.
D)The critical mass of these elements cannot be determined from only the number of neutrons per fission.

Question

Quizplus · Accepted Answer

The number of neutrons released per fission is directly related to the critical mass of the element. The more neutrons released per fission, the smaller the critical mass required for a sustained chain reaction. Since plutonium-239 releases an average of 2.7 neutrons per fission, it requires a smaller critical mass than uranium-235, which only releases an average of 2.5 neutrons per fission. Therefore, the answer is A) plutonium-239.

Uranium-235 Releases an Average of 2