What are several practical uses for the process of radioactive decay?

Halflife is very closely related to how my wife gets over being mad.

It never entirely goes away.

radioactive decay.it neat time,a lot of time to be decay under groyne

nuclear medicine studies.

Atomic batteries that power spacecraft are powered by U238 decay.  They generate heat which can be converted into elecrical energy.

Carbon dating comes from C14 decaying at a half life of 5700 years into C12.

Radiation therapy for prostate cancer involves placing cobalt "seeds" into the prostate, which slowly give off radiation to kill cancerous cells.

Preserving food - when food is exposed to ionizing radiation (beta or gamma rays), these can retard or eliminate growth. Low doses of radiation inhibits growth, and potatos are a good example of produce which has been irradiated. Higher doses of radiation can sterilize food products.

Radioactive tracers - sometimes it helps to monitor the flow of a substance, but physically observing the flow is impossible. A good example is oil flowing through the shaft of a well. Oil can be lost if there are cracks in the sides of the shaft, and a radioactive tracer can be introduced. If radiation is detected far from the shaft, it indicates a leak. These sorts of tracers are chosen based on short half lives and weak emissions. Most oil well tracers have decayed completely in under a year.

Cancer treatment - radiation is a popular form of cancer treatment. Cancer cells are not as robust as ordinary body cells and are therefore more sensitive to toxins and radiation. The cancer can be irriadiated by administering a radioactive substance. The treatement is especially effective if the radioactive isotope accumulates in the tissue which hosts the cancer. Thyroid cancer is treated with radioactive iodine, because the thyroid absorbs iodine. Other cancers can be treated by inserting tiny glass needles containing radioactive substances. Many cancers are treated by simply exposing the tumor to a beam of radiation produced by a machine.

Energy production - these are nucleur reactors. They are technically known as "fission reactors" because they split large atoms of Uranium and Plutonium into smaller atoms. Each big atom produces a pair of smaller isotopes, but the actual isotope is as random as breaking a rack of pool balls. The mass of the two smaller atoms will be less than the mass of the original one. This lost mass is converted into energy. E=MC^2, and since "C" is an enormous number, reactors generate tremendous amounts of energy. An ounce of nucleur fuel produces the energy of thousands of tons of coal.

Weapons of Mass Destruction - Uranium splits when a neutron strikes the nucleus of the atom at just the right velocity. The atom splits and produces another pair of neutrons. These can split another pair of atoms. under certain circumstances, this reaction is expoential and eventually all the nucleur material will undergo fission spontaneously. This releases unimaginable amounts of energy, mostly in the form of heat. nucleur reactors prevent this from happening by placing special neutron absorbing material around the nucleur fuel. This precisely controls the rate of decay. In a nucleur weapon, two chunks of plutonium are suddenly compressed by a precisely arranged set of explosive charges. This forms a "critical mass". Plutonium is so unstable that it will undergo spontaneous fission if enough of the metal is brought together. This generates a dense wave of neutrons which then penetrates the uranium case of the nucleur bomb.  This then results in a second wave of spontaneous fission.