U- 235 is a fissile isotope, meaning that it can split into smaller molecules when a lower-energy neutron is fired at it. U- 238 has an even mass, and odd nuclei are more fissile because the extra neutron adds energy - more than what is required to fission the resulting nucleus.

Is U-235 or U-238 more radioactive?

In general, uranium-235 and uranium-234 pose a greater radiological health risk than uranium-238 because they have much shorter half-lives, decay more quickly, and are thus more radioactive. Because all uranium isotopes are primarily alpha emitters, they are only hazardous if ingested or inhaled.

Why is uranium-235 and not uranium-238 the usual fuel of nuclear reactors?

Uranium-235 (natural abundance 0.71%) is very scarce and difficult to separate from uranium-238 (natural abundance 99.28%). The much more abundant uranium-238 does not undergo fission and therefore cannot be used as a fuel for nuclear reactors.

Why is U-235 a good isotope of uranium?

Natural uranium as found in the Earths crust is a mixture largely of two isotopes: uranium-238 (U-238), accounting for 99.3% and uranium-235 (U-235) about 0.7%. The isotope U-235 is important because under certain conditions it can readily be split, yielding a lot of energy.

Why is U-235 used in nuclear power plants?

Nuclear fuel—uranium Nuclear power plants use a certain kind of uranium, referred to as U-235, for fuel because its atoms are easily split apart. Although uranium is about 100 times more common than silver, U-235 is relatively rare. Most U.S. uranium ore is mined in the western United States.

Why is U-235 a special element?

This radioactive metal is unique in that one of its isotopes, uranium-235, is the only naturally occurring isotope capable of sustaining a nuclear fission reaction. (An isotope is a version of the element with a differing number of neutrons in its nucleus.)

What is U-235 used for?

What is it used for? Uranium “enriched” into U-235 concentrations can be used as fuel for nuclear power plants and the nuclear reactors that run naval ships and submarines. It also can be used in nuclear weapons.

Can you eat plutonium?

It is not very toxic when ingested with food or drink because of its very small probability of passing through the intestine walls into the bloodstream. Pu forms large molecules, which have great difficulty in passing through membranes.