Commercial uses of radiation include irradiators (machines used to kill bacteria and other pathogens in food and other items), devices that test the density of highway and construction materials, emergency exit signs, pacemakers, smoke detectors, and security screening at airports and shipping ports.
- Radioluminescence is the phenomenon by which light is produced in a material by bombardment with ionizing radiation such as beta particles. Radioluminescence is used for emergency exit signs or other applications where light must be produced for long times without external energy sources. Formerly, radioluminescent paint was used for clock hands and instrument dials allowing them to be read in the dark.
- Tritium lighting is made using glass tubes with a phosphor layer in them and tritium gas inside the tube. Such a tube is known as a “gaseous tritium light source” (GTLS), or beta light, (since the tritium undergoes beta decay). Tritium is used with phosphor in rifle sights to increase nighttime firing accuracy. Some runway markers and building exit signs use the same technology, to remain illuminated during blackouts. Watchmakers also currently use tritium to make dials glow.
- Betavoltaics are generators of electrical current, in effect a form of battery, which use energy from a radioactive source emitting beta particles (electrons). A common source used is the hydrogen isotope, tritium. Unlike most nuclear power sources, which use nuclear radiation to generate heat, which then is used to generate electricity (thermoelectric and thermionic sources), betavoltaics use a non-thermal conversion process; converting the electron-hole pairs produced by the ionization trail of beta particles traversing a semiconductor. Betavoltaic power sources are particularly well-suited to low-power electrical applications where long life of the energy source is needed, such as implantable medical devices (artificial pacemaker and cochlear implants) or military and space applications.
- Smoke detector: An ionization smoke detector includes a tiny mass of radioactive americium-241, which is a source of alpha radiation. Two ionization chambers are placed next to each other. Both contain a small source of 241Am that gives rise to a small constant current. One is closed and serves for comparison, the other is open to ambient air; it has a gridded electrode. When smoke enters the open chamber, the current is disrupted as the smoke particles attach to the charged ions and restore them to a neutral electrical state. This reduces the current in the open chamber. When the current drops below a certain threshold, the alarm is triggered.
DID YOU KNOW?
FIRE SAFETY IS NO ACCIDENT—thanks to the smoke detector.
Fire Safety Tip
Experts say the simple act of installing smoke detectors on each floor of your home can go a long way toward saving your family from a fire. Smoke detectors, first patented in 1902, have saved countless lives. Today, the ionization smoke detector is the most commonly used. This type of smoke detector is one of the many applications of research done by nuclear scientists and engineers. The ionization smoke detector uses a tiny bit of radioactive americium-241, a source of alpha radiation. An air-filled space between two electrodes creates a chamber that permits a small, constant current to flow between the electrodes. If smoke or heat enters the chamber, the electric current between the electrodes is interrupted and the alarm is triggered. This smoke alarm is less expensive than other designs and improves the original smoke alarm by measuring more than the heat of a fire. It can detect particles of smoke too small to be visible.
Read more about nuclear applications