Concentration whole body radionuclide

Whole Body Radionuclide Concentration Factors and Turnover Rates. A series of experiments were performed to determine the turnover rates and concentration factors of Co, Cs, Mn, and Zn in the marine clam Mya arenaria and the oyster Crassostrea gigas. 

During refueling, the respective concentrations were 1.64, 1.33, 0.78, 0.19, and 6.34 mBq/m3 (44.3, 35.9, 21,5.1, and 171 fCi/m3). The derived air concentration recommended by the ICRP for occupational exposure is 80.0 mBq/m3 (2,200 fCi/m3). In 1997, the French radiation protection office conducted monitoring (24-hour urine analysis/whole body activity measurements) of workers in the non-nuclear energy field (i.e., nuclear medicine, research laboratories, and non-nuclear industries) to ascertain the occupational intake of radionuclides (De Vathaire et al. 1998). 241Am was not detected in samples from any of the 37 workers who worked with the isotope. 

Edible tissues from terrestrial animals, aquatic animals, and fowl are measured for radionuclide content to estimate the radiation dose to humans from food consumption. Organs and tissue that concentrate radionuclides, such as radioiodine in thyroids or radiostrontium in bones and teeth, are analyzed as indicators of such radionuclides in the environment. Domestic animals are sampled at the normal time of slaughter. Wildlife samples can be obtained from hunters or by special collections. Because radionuclide concentrations in animal tissues vary widely, depending on species, feed or inhalation intake, location, and individual metabolism, multiple animals must be sampled to establish a normal range of radionuclide concentrations. Radionuclides that emit gamma rays can be measured in live animals by a technique similar to whole-body counting in humans. 

This group, created by Congress, collects, analyzes, develops, and disseminates information and recommendations on radiation quantities, measurements, and units. NCRP publishes maximum permissible levels of external and internal radiation. The major handbooks are entitled Maximum Permissible Body Burdens and Maximum Permissible Concentrations of Radionuclides in Air and Water for Occupational Exposure and Review of the Current State of Radiation Protection Philosophy. The NCRP suggests an annual permissible whole-body dose of 5 rem/year, with 3 rem permitted within a 13-week period. 

Direct monitoring of incorporated radionuclides is based on whole-body measurement of the penetrating (primarily y) radiation. Indirect methods are used for those radionuclides, such as tritium, which do not emit a significant amount of penetrating radiation and are based on the determination of activity concentrations in biological materials separated from the body (urine, feces, and breath samples), or in other physical samples taken from the close environment. 

The uncertainties in the modelling of internal doses can be substantially reduced when some crucial parameters are evaluated by measurement and some site specific corrections are introduced. The most reliable method of validation of an ingestion model is by comparing its predictions with internal dose assessments made on the basis of data from individual measurements of radionuclide contents in the human body performed by whole body counting or by analysis of the concentrations of radionuclides in excreta. 

While operators are not required to be proficient in use of the Appendix B tables referred to above, we will cover in class discussions and handout problems to the extent that you will become familiar with the content and application of the tables. Note that releases to the sanitary sewer system are governed by University radiation safety regulations and specific UWNR procedures as well as by 10 CFR Part 20.2003. Releases to the environment for both air and water are covered by lOCFR 20.2001-20.2006, Appendix B, effluent concentration, Columns 1 and 2, and by specific UWNR procedures (to be covered later). The notes at the end of Appendix B indicate how to handle mixtures of radionuclides and situations in which all of the radionuclides in the effluent are not identified. For most materials, maximum permissible concentrations in air and water are dependent upon whether or not the material is water-soluble. For inert gases, such as Ar-41 the limit has the notation "Sub", which means the concentration limit is based on external radiation to the whole body from submersion in an infinite cloud of gas at that concentration, not on accumulation of a body burden or dose to a critical organ. 

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