Biological Effects of Activation Products and Other Chemicals Released from Fusion Power Plants

摘要

Tritium released as tritium oxide will behave like ordinary water throughout the hydrosphere, and is readily metabolized by all living organisms. Although most biochemical reactions dis¬criminate against the incorporation of tritium, the possibility of some concentration should not be overlooked. A fraction of tritium in the body as tritiated water becomes organically bound;that is, exchanges with hydrogen bound in organic molecules. However, organic binding is not expected to result in significant bioaccumulation of tritium from tritiated water, because water is approximately as hydrogen rich (~11% by weight) as any compound of the biological organism (~10% by weight). Processes that allow accumulation and incorporation of tritium assist in its elimination. Tritium, which is organically bound, demonstrates a longer half-time in the body, but it would appear to constitute a small fraction of the total tritium label.nTritium released as HT is of much less concern than HTO because it is not readily incorporated into living organisms. The dose rate for HT is only 0.5% of the dose rate for HTO.nExtensive studies over the past 30 years have failed to produce tritium effects data significantly different from those which might have been predicted from a general knowledge of the effects of ionizing radiation. Although recent biological effects studies suggest uncertainty as to the appropriate RBE for tritium, this would likely be no greater than three or four. However, if fusion reactors hold tritium releases within ICRP standards, no significant impact to the envi¬ronment from those releases are expected.nAmple information is available to permit reasonable estimates of the dose rates and biological effects for tritium. However, some uncertainties still exist and should be eliminated by continu¬ing research.