The Relative Abundance of Tritium

DOE-HDBK-1132-99

1,000 to 1 x 10 6 Ci/yr, respectively, for each 1,000 MW of electrical power.

Commercial producers of radioluminescent and neutron generator devices also

release about 1 x 10 6 Ci/yr. Thus, tritium facilities operate within a background

of tritium from a variety of sources.

The Relative Abundance of Tritium . The isotopes of elemental hydrogen

2.10.3

have long been recognized as being special-- so special, in fact, that each has

been given its own chemical name and symbol. Protium, for example, is the

name given to the hydrogen isotope of mass-1, and the chemical symbol for

protium is H. Deuterium is the name given to the hydrogen isotope of mass-2;

the chemical symbol for deuterium is D. Tritium is the name given to the

hydrogen isotope of mass-3. Its chemical symbol is T.

Protium is by far the most abundant of the hydrogen isotopes. Deuterium

follows next with a relative abundance of about 1 atom of deuterium for every

6,600 atoms of protium; that is, the D to H ratio (D:H) is about 1:6,600. Tritium

is the least common hydrogen isotope. The relative abundance of naturally

occurring tritium (i.e., tritium produced in the upper atmosphere and tritium

injected directly by the sun) has been estimated to be on the order of 1 tritium

atom for every 1018 protium atoms. The introduction of man-made tritium into

the environment, particularly as a result of atmospheric testing, has raised this

level approximately one order of magnitude so that the ambient T to H ratio is

now approximately 1:10 17.

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