Investigation of the Environmental Fate of Tritium in the Atmosphere

INVESTIGATION OF THE ENVIRONMENTAL FATE OF TRITIUM IN THE ATMOSPHERE
Accidental airborne releases can raise the contribution of HT to values on the order of 60%
of the total tritium discharged (Murphy and Pendergast, 1979). By comparison, the amount
of tritium released in the liquid effluents seems to represent approximately 10% of the
airborne releases (NCRP, 1979). Releases from tritium production facilities can be reduced
through the implementation of measures to optimize tritium yields during processing (Jacobs,
1968).
Tritium can also be produced in accelerators by bombarding 3 He with neutrons (as depicted
in Figure 2.4), although this approach has not been applied on a large scale (Zerriffi, 1996).
Tritium can be formed in the light water cooling of electron or proton accelerators primarily
through spallation of the oxygen atoms in the water molecules. Small amounts of tritium
can also be produced through spallation of nitrogen, carbon and other light molecules. It is
possible that some releases of this tritium to the environment can occur through airborne
releases and possibly liquid releases depending upon the design of the cooling system.
2.4.5 Consumer Products
The fractional release of tritium, in the form of HTO, HT and short-chain organic radicals
of the styrene type, from luminous compounds (such as those used as dial paints for the
illumination of timepieces), comprises approximately 5% annually (Comps and Doda, 1979;
Krejci, 1979; Krejci and Zeller, 1979; UNSCEAR, 1977; Wehner, 1979). Such releases can
represent amounts on the order of 10 14 Bq tritium per year (Krejci, 1979).
Tritium releases from gas-filled tubes, such at those used in liquid crystal displays (LCDs)
and inside exit signs or electronic tubes are negligible in comparison, showing values of
approximately 2 x 10 12 Bq tritium per year (Krejci, 1979; UN, ILO and WHO, 1983). That
said, however, environmental releases following accidental breakage of tubes or improper
disposal can be significant (Comps and Doda, 1979; Wehner, 1979).
Mutch and Mahony (2008) reported tritium levels in municipal landfill leachates, which
were attributed to disposal of such products. In a study of ten landfills in New York and
New Jersey, the average tritium as HTO in leachate was 1,251 Bq/L and the maximum was
7,104 Bq/L. A similar study of California landfills indicated an average tritium in leachate
of 3,663 Bq/L and a maximum of 11,248 Bq/L. Landfill gas condensates in U.K. and
California studies had tritium concentrations as high as 2,013 Bq/L and 18, 981 Bq/L,
respectively.
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