What Is Tritium?

The Nuclear Regulatory Commission (NRC) says tritium is a naturally occurring radioactive form of hydrogen produced in the atmosphere when cosmic rays collide with air molecules, so it is found in very small or trace amounts in groundwater throughout the world, and that it is also a byproduct of the production of electricity by nuclear power plants. The EPA says tritium is also produced during nuclear weapons explosions and as a byproduct in nuclear reactors, and that although it can be a gas, its most common form is in water, because radioactive tritium reacts with oxygen to form water.

The NRC says tritium emits a weak form of radiation, a low-energy beta particle similar to an electron, that does not travel very far in air and cannot penetrate the skin. The EPA says tritium primarily enters the body when people swallow tritiated water, inhale it as a gas or absorb it through the skin, that once inside it disperses quickly and is distributed throughout the body, and that it is excreted through the urine within a month or so after ingestion.

The NRC says the EPA dose-based drinking water standard of 4 millirem per year is based on a maximum contaminant level of 20,000 picocuries per liter for tritium, and that its inspections evaluate nuclear power plant programs to inspect, assess and repair equipment and structures that could leak, as well as the ability of a plant to analyze how spills or leaks could affect groundwater. EPA RadTown says no radiation is emitted from a working, unbroken tritium exit sign, but that if a sign is damaged, for example when dropped during installation or smashed in a building demolition, the tritium could be released.