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Tritium (from Ancient Greek τρίτος (trítos) 'third') or hydrogen-3 (symbol T or 3 H) is a rare and radioactive isotope of hydrogen with a half-life of ~12.3 years. The tritium nucleus (t, sometimes called a triton) contains one proton and two neutrons, whereas the nucleus of the common isotope hydrogen-1 (protium) contains one proton and no neutrons, and that of non-radioactive hydrogen ...
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common types of decay are alpha, beta, and gamma decay.
One type of natural transmutation observable in the present occurs when certain radioactive elements present in nature spontaneously decay by a process that causes transmutation, such as alpha or beta decay. An example is the natural decay of potassium-40 to argon-40, which forms most of the argon in the air.
Rutherford applied the principle of a radioactive element's half-life in studies of age determination of rocks by measuring the decay period of radium to lead-206. Half-life is constant over the lifetime of an exponentially decaying quantity, and it is a characteristic unit for the exponential decay equation.
For this reason, at the moment of reactor shutdown, decay heat will be about 7% of the previous core power if the reactor has had a long and steady power history. About 1 hour after shutdown, the decay heat will be about 1.5% of the previous core power. After a day, the decay heat falls to 0.4%, and after a week it will be 0.2%.
It is the mechanism of interaction between subatomic particles that is responsible for the radioactive decay of atoms: The weak interaction participates in nuclear fission and nuclear fusion. The theory describing its behaviour and effects is sometimes called quantum flavordynamics ( QFD ); however, the term QFD is rarely used, because the weak ...
The four most common modes of radioactive decay are: alpha decay, beta decay, inverse beta decay (considered as both positron emission and electron capture), and isomeric transition. Of these decay processes, only alpha decay (fission of a helium-4 nucleus) changes the atomic mass number ( A ) of the nucleus, and always decreases it by four.
In chemistry, the decay technique is a method to generate chemical species such as radicals, carbocations, and other potentially unstable covalent structures by radioactive decay of other compounds. For example, decay of a tritium -labeled molecule yields an ionized helium atom, which might then break off to leave a cationic molecular fragment.