Maximum permissible concentration radionuclides

Maximum Permissible Body Burdens and Maximum Permissible Concentration of Radionuclides in Air and in Water for Occupational Exposure, ReportNo. NCRP, No. 22, National Council on Radiation Protection and Measurement, Washington, D.C., 1959. 

One measure of the hazard associated with this waste is the water dilution volume (m3). The water dilution volume is the volume of water needed to dilute a radionuclide to its maximum permissible concentration in water. A plot of the water dilution volume (WDV) for spent fuel is shown in Figure 16.11. 

HEW and the Federal Radiation Council have been assisted by the technical recommendations of the National Council on Radiation Protection and Measurements. The NCRP has been particularly involved in developing the concept and the values of the maximum permissible concentrations (MPC) of radionuclides in water, which values could be applied to foods (16). [The National Council on Radiation Protection and Measurements was created on July 14,1964, by Public Law 88-376. The council is the successor to the unincorporated association which was known as the National Committee on Radiation Protection and Measurements and which for 35 years served as the focal point for developing radiation protection philosophy and standards in the United States. The current address of the NCRP is 4201 Connecticut Ave., N.W., Suite 402, Washington, D. C.]... 

One result of studies on these persons with varying radiation histories has been the development of criteria on the maximum permissible concentrations of radioactivity in air and in water ingested by the population. The criteria factors that determine the hazards of the various radionuclides include ... 

These factors have been used to develop the tables of maximum permissible concentrations (16) in air and in water for various conditions (40-hour week or 168-hour week) and for various organs (skin, bone, kidney, liver, brain, GI tract, and total body), but all assuming an occupational exposure and an exposure period of 50 years. MPC values have been developed for 234 radionuclides found in nature, in radioactive fallout, and in neutron activation studies. 

Radioactivity and Toxicity. Table III lists the radionuclides in aged waste, their half-lives, the expected radioactivity of each after 10 years aging, and the relative toxicity of each. Relative toxicity is defined as the ratio of the concentration of a given isotope to its maximum permissible concentration in public zone water. Mercury, nitrate, and nitrite (although not radioactive) are also listed because their toxicity is actually greater than that of many of the radioactive nuclides. Sr and Cs are... 

Radioactive waste is any waste material—gas, liquid, or solid—whose radioactivity exceeds certain limits. These limits have been established by governments or by local authorities, guided by the recommendations of the International Commission on Radiation Protection (ICRP). The ICRP recommendations define the maximum permissible concentration (MPC) for each individual radionuclide and for mixtures of radionuclides in water or air. The U.S. regulation defines such limiting concentration as the radioactivity concentration limit (C), which is the terminology used in this text, Values of C for selected actinides and long-lived fission products in water or air are given in App. D. 

The recommendations of the International Commission on Radiological Protection (ICRP) for maximum permissible concentrations of radionuclides in air and water serve as basic criteria for determining radionuclide concentrations in air and water. For the first estimation, measurements of gross a, / , and y activities are sufficient however, in order to draw a responsible conclusion, individual radionuclides in the sample have to be determined. 

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. 

Radiotoxicity of a radionuclide is inversely proportional to its maximum permissible concentration, MFC. Ingestion radiotoxicity - see the vertical axis of O Fig. 61.2 - can be expressed as a minimum of water that is still drinkable if the unit mass of the substance containing the given radionuclide is dissolved in it (p. 2802). 

The first substantial report comprising nearly a hundred pages was published by the ICRP in 1955 as a supplement No.6 to the British Journal of Radiology. This report also included the maximum permissible concentration (MPC)-values for about 90 radionuclides. 

This material balance method would appear to have wide application for studying process rates in natural streams regardless of their location since less than maximum permissible concentrations of were used while radionuclide levels in periphyton and water were sufficient to monitor for at least six weeks following the release.. . . Since P has a short physical half-life (14.3 days), there is no danger of high residual concentrations in a stream ecosystem following the release because of radioactive decay. Thus, repeated releases may be made to the same stream to determine changes in biomass, primary production rate, and primary consumption rate on a seasonal basis. 

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. 

As a result of calculations based on a knowledge of the factors above, it is possible to set limits on the discharges of specific radionuclides from the nuclear plant. These limits are referred to as derived limits. They may specify simply the maximum allowable rate of release or the maximum permissible concentrations in air, water, or particular members of the relevant food chains. 

Fig. 2.8 Autoradiography of a young tomato plant the radio-nuchde used for obtaining the picture was not specified (Feller 2005). Here, there is some concentration maximum in the upper root also, but the radionuclide does accumulate in the edges/tips of leaves while the vasculae are depleted with respect to radio-nuchde (reproduced with permission)...

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