Chapter 40, Problem 32A

To determine

The reason for no occurrence of chain reaction in uranium mines.

Explanation of Solution

Introduction:

The subsequent fission reaction triggered by the neutrons of the primary fission reaction is called a chain reaction. The chain reaction may be controlled or uncontrolled.

The two isotopes are found in the mines and these are U-238 and U-239. The amount of U-238 is very large compared to U-239.

U-238 does not undergo nuclear fission by absorbing the neutron. The nucleus of U-238 is changed to U-239. U-239 can undergo nuclear fission by absorbing a neutron.

A large amount of the uranium exists in the form of U-238 in mines. So, the chain reaction does not occur in the uranium mines.

Conclusion:

Thus, the chain reaction does not occur in the uranium mines because most of uranium in mines remain in U-238 form, which cannot directly undergo fission reaction.