Standard radionuclides

The counting efficiency (e) of the proportional detector is calculated as the ratio of the net count rate, in s, to the activity (A), in Bq, of this standard radionuclide solution. The net count rate is the standard s gross count rate (RG) minus the detector s background count rate (RB). The reported disintegration rate (A) is the product of the radionuclide concentration, in Bq L 1, and the amount of counted sample, in L, adjusted for the radioactive decay of the radionuclide between standardization and measurement. Equation 2A.1 is the general form of this equation. 

A tracer usually is a solution of a standardized radionuclide that is an isotope of the analyte radionuclide. With the identical chemical behavior of tracer and analyte, the yield of the tracer, determined radiometrically, represents the yield of the analyte. In this respect, the radioactive tracer has the same function as the stable carrier. Furthermore, for alpha particles of the usual 4-10 MeV energy in a thin source, the ratio of net count rate to activity is the same for the tracer and the analyte, so that the analyte activity is directly calculated from the activity of the tracer and ratio of the net count rates at the peaks of the analyte relative to the tracer, measured with an alpha-particle spectrometer. 

Standardization by Counting. For this method, a detector initially is calibrated for detection efficiency pertinent to the utilized tracer with a standard radionuclide in quantity and radioactivity form that is known and traceable to NIST. The tracer solution is then prepared for counting, counted, and labeled for radionuclide concentration on the basis of the net count rate and the detection efficiency. Its activity is calculated together with the counting error, adjusted for radioactive decay and dilution. All of these measurements should be performed in replicate to provide average values and their measurement uncertainty. 

Standard radioactive Material (SRM) solutions are radioactive materials with accurately known radionuclide content and radioactive decay rate or rate of particle or y-ray emission. They are used primarily to calibrate radiation detection instruments and to prepare QC samples that test analytical accuracy. The supplier prepares radionuclide standard solutions in flame-sealed glass ampoules. Other standard radionuclides are in the form of point sources (usually on thin backing) or as solids in configurations that represent actual samples. 

Finally, Sec. 112 of the Clean Air Act required that EPA pronml-gate National Emission Standards for Hazardous Air Pollutants (NESHAPs). Between 1970 and 1989, standards were promulgated for asbestos, beiylhum, mercuiy, vinyl chloride, benzene, arsenic, radionuclides, and coke-oven emissions. 

Radiopharmaceuticals have one of two general functions (1) they may be used to detect or image biological problems such as tumors and (2) they may be used to treat an illness. Which type of radiation (a, p, or y) would be the most suitable for (a) detection and (b) therapy Justify your selections, (c) From standard literature sources, find at least two radionuclides that have been used for imaging body tissues, (d) What are the half-lives of these radionuclides ... 

Byrne AR 1993) Review of neutron activation analysis in the standardization and study of ref erence materials including its application to radionuclide reference materials. Fresenius J Anal Chem 345 144-151. 

The fc0-NAA method has been developed to overcome the labour-intensive and time-consuming work of preparing multi-element standards when routine multielement or panoramic analyses are required [447]. It is intended to be an absolute technique in which uncertain nuclear data are replaced by a composite nuclear constant, the T 0-factor, which has been determined experimentally for each radionuclide with high accuracy. This k0 is given by ... 

EPA proposed standard in 4( X I R 191 (EPA. 1985). Releases of radionuclides from the repository were to be limited to amounts such that the projected number of premature cancer fatalities over a 10,000 year period would not exceed 1000, i.e. an average of one per decade.2 This target appeared to be attainable until it was... 

NCRP (1959). National Committee on Radiation Protection and Measurements, Maximum Permissible Body Burdens and Maximum Permissible Concentrations of Radionuclides in Air and in Water for Occupational Exposure, NCRP Report No. 22, published as National Bureau of Standards Handbook No. 69 (National Council on Radiation Protection and Measurements, Washington). 

SC-18 Standards and Measurements of Radioactivity for Radiological Use SC-24 Radionuclides and Labeled Organic Compounds Incorporated in Genetic Material... 

Welander, A.D. 1969. Distribution of radionuclides in the environment of Eniwetok and Bikini Atolls, August 1964. Pages 346-354 in D.J. Nelson and F.C. Evans (eds.). Symposium on Radioecology. Proceedings of the Second National Symposium. Available as CONF-370503 from The Clearinghouse for Federal Scientific and Technical Information, Natl. Bur. Standards, Springfield, VA 22151. 

Individual Standard Reference Materials containing 14C, 3H, and some naturally occurring uranium and thorium series radionuclides are available from the National Institute of Standards and Technology (NIST). These include ... 

Am, 90Sr, 239Pu, 240Pu, 137Cs, 129I, or 14C, which also lack solution standards. NIST has an active program to address the development of all of these radionuclide standards except 14C. 

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