Tritium environmental

Personnel are protected in working with tritium primarily by containment of all active material. Containment devices such as process lines and storage media are normally placed in well-ventilated secondary enclosures (hoods or process rooms). The ventilating air is monitored and released through tall stacks environmental tritium is limited to safe levels by atmospheric dilution of the stack effluent. Tritium can be efficiently removed from air streams by catalytic oxidation followed by water adsorption on a microporous soHd absorbent (80) (see Absorption). 

Analysis and Public Health Aspects of Environmental Tritium... 

Starting with the atmospheric thermonuclear tests, tritium concentration in the Northern Hemisphere has increased considerably above the natural background of approximately 10 pCi/liter of water (5). Since the cessation of these tests, environmental tritium concentrations have decreased gradually. Tritium is, however, produced in every nuclear reactor to some extent as a product of fission (1) or the activation of deuterium. In particular, reactors with heavy water as the moderator or cooling agent produce a large amount of tritium. Inasmuch as no... 

This paper summarizes some of the recently developed methodology used at the Southeastern Radiological Health Laboratory to determine environmental tritium concentrations. Since some of the methods used are not yet available in the literature, their development and essential features are discussed. Selected data on environmental tritium concentrations are presented and interpreted. 

The Bureau of Radiological Health (BRH) of the Public Health Service for many years has been analyzing and evaluating environmental tritium. Several networks comprising various media have been established. Surface waters, rain, urine, and food are analyzed by the Southeastern Radiological Health Laboratory, and the results are reported periodically in Radiological Health Data and Reports. 

Murphy, C.E., Watts, J.R. Corey, C.E. (1977) Environmental tritium transport from atmospheric release of molecular tritium. Health Physics, 33, 325-51. 

Schell, W.R., Sanzay, G. Payne, B.R. (1974) World distribution of environmental tritium. In Physical Behaviour of Radioactive Contaminants in the Atmosphere, pp. 396-400. Vienna IAEA. 

Allison, G.B. and Hughes, M.W. (1975) The use of environmental tritium to estimate recharge to a South-Australian aquifer. J. of Hydrology 26, 245-254. 

The natural inventory of tritium produced by this reaction is about 4 x lO Bq (11 kg), of which 90% is contained in the ocean as HTO. The tritium produced by man s activities (largely thermonuclear weapons testing) has increased to approximately 2 x 10 ° Bq. Although most of this tritium has been transferred to the oceans, environmental tritium is still half an order of magnitude higher than was present before nuclear testing. 

Allison G. B. and Holmes J. W. (1973) The environmental tritium concentrations of underground water and its hydro-logical interpretation. J. Hydrol. 19, 131 — 143. 

Engesgaard P., Jensen K. H., Molson J., Erind E. O., and Olsen H. (1996) Large-scale dispersion in a sandy aquifer simulation of subsurface transport of environmental tritium. Water Resour. Res. 32, 3253-3266. 

Gvirtzman H. and Magaritz M. (1986) Investigation of water movement in the unsaturated zone under an irrigated area using environmental tritium. Water Resour. Res. 22, 635-642. 

Precise liquid scintillation counting (LSC) methods to measure environmental tritium concentrations generally require enrichment of the samples (Ampur, 1974, Brown and Grummitt, 1956, Gentry a., 1973, Sauzay and Schell, 1972, Theodorsson, 1974). Enrichment by either electrolytic or... 

A new method for measuring environmental tritium levels without enrichment was recently developed by the authors (Cawley t al , 1980). This method is basically a double isotope, external standard count procedure which eliminates the background by measuring tritium free water scimples ("dead water" samples) and applying a difference method. 

The most delicate part of the method developed to measure environmental tritium levels is the elimination of the background. A difference method has been applied for this purpose using "dead water" samples, i.e. tritium free water samples obtained from National Bureau of Standards. 

This method of measuring environmental tritium requires neither the large capital costs nor the large operating expenses of the enrichment techniques. While counting times may be long, the sample requires minimal preparation. 

It is a simple, reliable and inexpensive method to estimate environmental tritium with acceptable precision (Table I). 

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