When an atom splits it gives off what?

Answer 1

What species are given off when an atom "splits" depends on what causes the atom to split. There are four ways an atom can split: 1) Using a cyclotron or a syncrotron, some species traveling at very high velocity is collided into an atom. The atom may spit depending on the isotope of the atom used, the species it collides with and the velocity of the species. 2) Certain isotopes can capture a "slow" or "thermal" neutron after which the isotope will fission. 3) Certain isotopes are capable of splitting after being hit with a "fast" neutron. Slow neutrons must have a kinetic energy below a specific value, and fast neutrons must have a kinetic energy above a specific value. The kinetic energies required vary depending on the isotope capturing or being hit with a neutron. 4) There are a few isotopes that undergo spontaneous fission, meaning that they will fission without capturing or being hit with a neutron.

In case 1, if the atom splits, it and usually also the species with which it collides, disintegrates into at least two of the following species: isotopes with a smaller mass, subatomic particles and photons of electromagnetic radiation. For case 2, there are about nine or ten isotopes capable of capturing a slow neutron. These isotopes are named "fissile" isotopes, not to be confused with a "fissionable" isotope, which includes any isotope capable of undergoing nuclear fission regardless of the mechanism of the fission (not including fission caused in an atom smasher). Almost instantly after capturing a slow neutron, a fissile isotope becomes a new isotope of the same element, but with a nominal Atomic Mass of one AMU greater. The heavier isotope is unstable an immediately fissions into two lighter isotopes and releases at least one neutron plus ionizing radiation such as a gamma ray(s), beta particle(s) or an alpha particle(s). It is impossible to know what the two lighter isotopes are; one only knows the probability that the atom will split into two specific species. During the last approx. 70 years, socalled "fission curves" were emperically determined for the known fissionable isotopes. A fission curve is a graph that plots the mass of the fission products vs. the probability that a pair of specific lighter isotopes will be formed. In case 3, there are a handfull of isotopes that may split if they collide with a fast neutron traveling above a specific velocity. Each of these isotopes also has its own fission curve. Case 4 applies to the small number of isotopes that can split spontaneously, that is, without capturing or colliding with a neutron. Again, each of these isotopes have a specific fission curve.

It is important for someone who considers themselves a "Scientist" to know that only a very small fraction of all the isotopes are capable of "splitting," and, only if one of those isotopes disintegrates in a atomic accelerator, is the fissionable material in a "fast neutron" or a "fast flux" nuclear reactor, or is a constituent of a thermonuclear bomb. Lastly, a scientist should avoid using the word "split" when describing nuclear fission because that word implies that something hits an atom hard enough to cause it to break into pieces, and, in my opinion, causes most people to think that just about any atom will spit if it is hit hard enough by whatever. All 104 of the commerical nuclear power reactors in the USA, all the ones in Canada and in Europe, and probably in the rest of the world, operate by slow neutron capture by U-235 (and to a much lesser degree Pu-239) followed by nuclear fission. In other words, neutrons do not slam into U-235 or Pu-239 atoms breaking them into pieces.

All or virtually all commercial power reactors operate as follows: The nuclear fuel is a blend of uranium (238) oxide and uranium (235) oxide. Only about 0.7-2.5% of the uranium atoms are U-235, which is the primary isotope responsible for generating the heat that either causes the water in the reactor to boil or turns it into steam outside of the reactor vessel, depending on the design of the plant. A U-235 atom captures a neutron that has been slowed by normal water, heavy water (deuterium oxide, which is not radioactive) or graphite to form U-236. U-236 is an unstable isotope and breaks into two lighter isotopes, according to its fission curve, and releases an average of 2.4 neutrons. The entire process is incredibly fast, only taking a few nanoseconds to occur. Some of the neutrons from the U-235 fission go on to be captured by other U-235 atoms, however some of them must be captured to prevent a run-away chain reaction. Materials in the control rods are very efficient at capturing neutrons, and some plants add boron to the reactor water since boron is also efficient at capturing neutrons. Maintaining a nearly perfect balance that allows the right concentration of neutrons is necessary to keep the plant running.

Because of numerous automatic safety functions required in the USA, Canada and Europe, it is literally much more difficult to keep a plant running than to have an accident. If all of the nuclear operators just walked out of the control room, the plant would automatically shut down. The Three Mile Island accident was caused when improperly trained operators intentionally over-rode one or more automatic safety mechanisms. Even then, only a very small amount of tritium (H-3) was released from the plant, even though the reactor was ruined. Newer plants and all existing plants were designed or upgraded to prevent anyone from preventing or over-riding certain safety functions. The problem with Chernobyl was that the operators were performing some kind of unauthorized experiment that caused much of the water in the reactor to be lost. When they began to add water back into the reactor, the fuel was so hot that it caused the water to instantly turn to steam, and that caused a steam explosion that ruptured the reactor vessel. To make it worse, Chernobly was a graphite-moderated reactor, and without water and now with air able to enter the reactor, the graphite moderator ignited. None of the countries listed nor Japan has any graphite reactors.