Why is uranium-235 the most common isotope for nuclear fission in current use in nuclear power generation?

Uranium is the basic element found in abundance on Earth. 

Nuclear fission occurs when one atom splits into two, creating energy. Spontaneous fission occurs all the time. 

Uranium undergoes spontaneous fission at a very slow rate, and emits radiation. Uranium-235 (U-235) is only found in about 0.7 percent of uranium found naturally, but it is well-suited for producing nuclear power. 

This is because it decays naturally by a process known as alpha radiation. This means that it releases an alpha particle (two neutrons and two protons connected together). 

Another reason that U-235 is ideal for producing nuclear power is that unlike most materials, U-235 can undergo induced fission. When a free neutron collides with a U-235 nucleus, the nucleus will usually capture the neutron and split extremely quickly. The splitting of a single U-235 atom can release roughly 200 MeV (million electron volts).

Explanation:

In nuclear fission, the energy is released when the nuclei of the atoms are split apart. It is the method used by the nuclear plants to generate electricity.

The fuel used most widely by the nuclear power plants for fission is uranium. Uranium which is although abundant is nonrenewable source of energy.

Two isotopes of uranium are found in the nature, uranium-235 and uranium-238.

Uranium-235 is commonly used for the energy production because its nucleus splits very easily when bombarded by neutron. During fission, uranium-235 absorbs bombarding neutron which causes the nucleus to split apart into the two atoms of lighter weight. The fission reaction releases energy in form of heat.

space exploration has led to the development and technological improvement of many everyday items. (if this answer is wrong i will find the right answer) : )