Walrus pups are able to swim at birth and weigh between 100 and 150 pounds. Most are only children (twin births are rare), and they stay with their mothers for two years. Eventually, their small young tusks will grow up to three feet long.
Definition of nuclear for Students. 1  1 : of, relating to, or being a nucleus (as of a cell) 2  2 : of or relating to the nucleus of the atom Fission is a nuclear reaction. 3  3 : produced by a nuclear reaction nuclear energy.  4 : of, relating to, or being a weapon whose destructive power comes from an uncontrolled nuclear reaction.
Nuclear fission. In nuclear physics and nuclear chemistry, nuclear fission is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts (lighter nuclei). The fission process often produces free neutrons and gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay.