Investigation On Internal Tritium Measurements And Metabolic Dynamics

Tritium, a very common cosmogenic radionuclide in nature and an artificial nuclide which can be produced in nuclear industry, will result in the public exposure dose and professional exposure dose. During nuclear power plants are running correctly, HTO, whether in liquid or gaseous state, is a very important radioactive effluence and the effluence of tritium is one of the nuclides which result in internal irradiation in radiation worker. Measurement of density of internal tritium and the research of tritium lead to dose is the main reference of the public exposure and the hazardous evaluation and protect of professional exposure of tritium. This experiment research the measurement of internal tritium and metabolic dynamics from three aspects.Cooperate with a light water reactor nuclear power plant , we collect some urine samples of workers who intake tritium, research the factors which influence the exacts of measurement of urine tritium, and compare three sample pretreatment methods,urine without deal, adding KMnO4 to distill stripping and directly distill stripping, and compare the exact and applicability of the counting efficiency of internal standard method and external standard method. Through systematic empirical study, we think that using low background Multi-purpose Scintillation Counter and adopting primitive urine sample with external standard scale efficiency method is more suitable for the quickly exact measurement of internal tritium density of a large number people taking tritium.Through the field experimentation, we research the biology elimination half-time of tritium and the ratio of the internal organism tritium. The experiment gets the half life of tritium in the human body is on an average of 10.6 days. Related With the staff's physical conditions and living habits. The concentration ratio of organically bond tritium to free tritium water is from 8.3% to 14.1% in the normal work condition, and when the workers intake tritium unexpectedly, the concentration of organically bond tritium will increase sharply, the biggest times is 32 as more as free tritium water, so the proportion of organically bond tritium can not be neglected.We calculate the cumulative accumulated-effective dose of tritium based on the data of internal tritium density.In practical work, some radiation worker continued to taking tritium for a period of time, so we use nuclide metabolic dynamics model to research the accumulation of internal tritium, metabolism and the accumulated-effective doses under a sustained intake of tritium conditions. Theoretical calculations and analysis show that one time measuring the concentration of tritium will underestimate the actual dose of intake tritium. So, under a sustained intake of tritium condition, we should calculate the cumulative accumulated-effective dose.