Chapter 24, Problem 65A

Interpretation Introduction

Interpretation:

The terms critical mass, subcritical mass and supercritical mass to be described.

Concept introduction:

Nuclear fission forms energy that is achieved by nuclear reactors. This energy is used to form electricity at nuclear power plants.

Answer to Problem 65A

Critical mass:

The lowest mass of a sample of fissionable material that is essential to maintain a nuclear chain reaction is termed as critical mass.

Subcritical mass:

In this mass, neutrons emerge before causing sufficient fission to sustain chain reaction thus chain reaction does not start.

Supercritical mass:

A sample of fissionable material is claimed to have supercritical mass, with a mass greater than the critical mass.

Explanation of Solution

Critical mass:

The lowest mass of a sample of fissionable material that is essential to maintain a nuclear chain reaction is termed as critical mass. Neutrons discharged in one fission that generates other fissions to happen on the presence of critical mass.

Subcritical mass:

Subcritical mass assign to a radio isotopic sample which is not sufficiently dense or massive to survive a fission chain reaction. In this mass, neutrons emerge before causing sufficient fission to sustain chain reaction thus chain reaction does not start.

Supercritical mass:

A sample of fissionable material is claimed to have supercritical mass, with a mass greater than the critical mass. In a supercritical mass, neutrons generate more and more fissions and chain reaction accelerates.

Conclusion

For a chain reaction to occur a sample of fissionable material must have adequate mass. If not, neutrons escape from a sample by hitting other nuclei before they can initiate chain reaction.