Description: hydrogen isotope existing naturally

Production: manufactured artificially by irradiation of lithium 6 and

during fission reactions

Military use: boosted or thermonuclear warheads; inertial fusion

Civilian use: research on controlled fusion for production of energy

Radioactivity: beta emitter

Comment: thermonuclear material

Like deuterium, tritium is a hydrogen isotope. However, it possesses

two neutrons and a proton, and is not stable. Tritium has a period of

12.3 years, and decays by losing a beta particle.

At ordinary temperatures, tritium is a gas (HT or H3); but in the

presence of oxygen, it spontaneously produces tritiated water (HTO).

In dry conditions, tritium gas is converted into tritiated water at the

rate of about 1% per hour. The conversion is more rapid in humid

conditions.

Tritium exists naturally. It is manufactured continuously in the

atmosphere by the interaction of cosmic radiation with nuclei of

nitrogen, oxygen, and argon present in the upper atmosphere. Mixed

with rain water, it is then deposited on the surface of the earth

[ACES 94]. But tritium is created also by human activities.

Production

Tritium is created artificially by irradiation of lithium targets; it

is also a by-product of nuclear tests and of the use of nuclear power

plants. Indeed, thermonuclear tests have injected "into the atmosphere

a quantity of tritium about 100 times greater than natural activity"

[Crii-Rad 95]. Reactors generate tritium in their fuel by ternary fission (which generates three products, the third being relatively light like tritium). For the most part, this tritium remains in the interior of the fuel and is freed only during reprocessing.

Pressurized water power plants, in particular, create tritium in their coolant, their moderator, and their control rods by activation of lithium, deuterium, and boron. In heavy water reactors, the absorption of neutrons by the deuterium of heavy water creates considerable quantities of tritium, which can be extracted and used.

Crii-Rad believes that groundwater fed by rainwater is subject to

contamination by nuclear tests and by natural tritium to a level of 4

Use

Tritium, like deuterium, is a thermonuclear material. Tritium-tritium

fusion is possible as is tritium-deuterium fusion. Therefore, the military uses tritium in boosted fission warheads and thermonuclear warheads, and also in studies of inertial confinement fusion. Because of the relatively short period of tritium, 5.5% of the tritium in a nuclear warhead disappears per year. So the military has to periodically replace the tritium in stocked warheads [NRDC 84]. On the civilian side, it is important for the studies of controlled fusion. It is intended also for other uses such as light sources, but that is outside the scope of this book.

Health

Tritium is not easy to handle safely. The beta irradiation emitted by

tritium is weak. Nevertheless, in the human body, this weakness can in

fact be an aspect of the destructiveness of this isotope, for all the

ionization power of the particle is concentrated on the part of the body where it is found [Fairlee 92]. Although the nuclear industry taken as a whole takes tritium lightly, it is a substance known to be at least carcinogenic.

Nuclear installations emit tritium in the form of gas and tritiated

water, which can contaminate the food chain. Tritium penetrates

human beings and other animals by breathing, by absorption through the skin, and by ingestion. Inhaled tritium spreads equally throughout the soft tissues: tritiated water mixes quickly with all the water in the body [ACES 94]. Since tritiated water is chemically identical to ordinary water, it is generally considered as much more radiotoxic than tritium gas, 25,000 times more, according to an IAEA study [AIEA 91].

It is less well understood that tritium bound organically can be

even more dangerous. It can irradiate the interior of the body for 550

days, compared to only 10 days for tritiated water. It concentrates doses to specific cells and organs instead of being diluted throughout all the body fluid.. Moreover, certain studies suggest that tritium is concentrated in the DNA where it can do genetic damage [Fairlee 92].

After an in-depth study of tritium, an advisory council of the

Tritium creates an enormous problem for the industry that produces

it. It is difficult and costly to separate tritium from the air, the

water, and objects that have absorbed it, and the results leave much to

be desired. Thus the usual method for capturing tritium gas is to

convert it into more toxic tritiated water. Moreover, it is extremely

difficult to store tritium. It is diffused through the least porosity.

Tritiated water will penetrate concrete unless it is provided with a

special cover. Tritium gas can penetrate rubber and most grades of

steel. Moreover, tritiated water in the presence of nitrogen generates

nitric acid which corrodes containers. Therefore, industry claims that

in general, the best way to deal with tritiated waste is to "dilute-

disperse" rather than to "concentrate and isolate". Thus, by far the

most important source in France, the plutonium production factories at

La Hague, dump almost all of the free tritium into the air and into the

which also is located on the seashore.

Deputy Chrisian Bataille in the second volume of his report L’évolution de la recherche sur la gestion des déchets nucléaires à haute activité, stated that tritium "presents incontestable dangers for human health that it is advisable never to forget." Farther on he wrote, "The authorities responsible for nuclear installations, whether civilian or military, should be conscious that releases of tritium into the environment threaten to become a major problem in future years and certainly one of the main themes of the antinuclear contestation [Bataille 97].

French sources

The first military test of a fission device boosted by tritium and

deuterium took place at Fangataufa in 1966. From 1962 to 1976, a

laboratory at Saclay was equipped for the production of important

quantities of tritium. The targets treated at Saclay were irradiated by

the plutonium-producing reactors at Marcoule and perhaps elsewhere.

Two reactors intended particularly for the production of tritium, the

Célestin, went into service at Marcoule in 1967 and 1968 respectively; and in 1967 also, at Marcoule the shop for the extraction of tritium from targets (Atelier d’extraction du tritium des cibles) began to recover thermonuclear material. The Célestin are still operating, but at a reduced level. France plans to begin production of tritium in the Réacteur d'essais à terre (RES) at Cadarache in 2012 and to end production of tritium in the Célestin at that time.  (RES will not go critical until 2007) [Boucheron 01].