Question

Explain (in detail) Nuclear Fission and Nuclear Fusion, why is one radioactive vs the other?What is the nuclear process in a reactor (Fission, or fusion), and what kind of decays is it going through (alpha, beta, or gamma)?What is Critical Mass in nuclear physics?

Answer 1

From the binding energy per nucleon Vs mass number curve, we know that, Fe-56 is the most stable nucleus with a value of binding energy per nucleon of about 8.8 MeV.

Fission:- All those nuclei lying to the right of Fe-56 in the curve has a tendency to split up in to lighter nuclei to achieve stability with a consequent release of energy, which is called the fission process.

Fusion:- All those nuclei lying to the left of Fe-56 in the curve has a tendency to combine under high temperature and pressure in to heavier nuclei to achieve stability with a consequent release of energy, which is called the fusion process.

In fission the heavier nuclei undergo radioactive disintegration to form lighter nuclei while in case of fusion we need very high temperature to bring them close and combine.

In a nuclear reactior, we have controlled chain reaction of fission of U-235 (fuel), when bombarded with fast moving neutrons and undergo alpha decay.

The minimum amount of fissile material to make a chain reaction self sustaining, without change of power, energy or neutron population.