In the home
Many people are surprised to learn that a number of common consumer and household products are created by the nuclear industry. One, in particular, is designed to save lives and property.
While natural radiation surrounds us every day, scientists have spent decades refining the use of man-made radiation for the benefit of society. While nuclear medicine is the most obvious of these, radiation produced in nuclear reactors or cyclotrons has many other benefits that are integrated into common consumer and household items.
The most common of these is smoke detectors which are compulsory in Australia, saving lives and property. The most widely-used smoke detectors contain minute amounts of Americium-241** a transuranic element with an extremely useful property - its half-life. This produces alpha particles at a rate which creates an easily monitored steady voltage in the air between a pair of electrodes enclosed within an inexpensive plastic housing equipped with a simple circuit.
When the voltage changes significantly, it triggers an audible alarm. The main cause of such a voltage change is variation in the composition of air - smoke being one probable cause. This is why modern smoke detectors may also register steam, dust, hair spray and other household aerosol packs.
In the case of smoke detectors, the nuclear industry has utilised Americium-241's half-life in a clever way for the benefit of society.
Watches, clocks, ceramics and glassware
Modern watches and clocks sometimes use a small quantity of hydrogen-3 or promethium-147 isotopes as a source of light. Older watches and clocks used radium-226 as a source of light, hence those dials that light up in the dark. They were originally designed for pilots flying at night during World War II.
Ceramic materials such as tiles or pottery often contain elevated levels of naturally occurring uranium, thorium, and/or potassium concentrated in the glaze. Glassware, especially antique glassware with a yellow or greenish colour, can contain uranium. In fact, uranium glass (uranium was added to the mix prior to melting) was sold widely up until the 1920s and is now collectectable.
Other items that could be radioactive in the home include gemstones that have been irradiated in a reactor to improve their appearance; glass lenses in eyeglasses or sunglasses containing uranium and thorium; thorium mantles used in gas lanterns; magnetrons containing thorium used in microwave ovens; electric lamps containing thorium in the filament; television faceplates and automotive glass containing thorium; and uranium coated teeth and older dental products.
** According to the World Nuclear Organisation, Americium (atomic number 95) was first produced at the University of Chicago in 1945, during the Manhattan Project. The stable isotope, AM-241 has a half-life of 432 years and decays by emitting alpha particles and intense gamma radiation to become neptunium-237.