Early surveillance around coastal nuclear installations

Several biological systems have been used to detect extremely small amounts of radioactivity emanating from nuclear reactors that discharge directly into marine environments.Special attention has been given to plutonium.Inorganic absorbing systems, including certain ferrocyanides, provide convenient and sensitive means for monitoring the caesium radionuclides in sea water.These may well be used for monitoring automatically.Generally, the absolute concentrations of radiocaesium can be determined by comparisons with the concentrations of the natural nuclide, caesium-133s that is present in the marine environment at a level that frequently may be predicted.Selected plants have been found most useful, when samplings are normalized against surface area.Certain brown algae are useful for monitoring plutonium, especially nuclide ratios.Silver and cobalt nuclides accumulate preferentially in red algae and marine grasses.Surveillance by means of marine animals is sometimes more sensitive, but proper sampling and interpretations are much more difficult.Several of the common molluscs may be used effectively as monitors of cobalt, silver and other nuclides.Larger fish, whenever their exposure pattern can be estimated, may be exploited for monitoring various metal nuclides through the use of selected organs.Marine biological systems are frequently such sensitive indicators that account must be made of contributions from many sources, even from global fallout more than ten years old.Successful biological surveillanc of a given nuclear installation generally requires comparisons of nuclide ratios at several distances using consistent tissues at consistent seasons.