Radioactive materials quantities

Notification to the NRC and the states is also required prior to the transport of Category 1 radioactive material quantities of concern, as described in 10 CFR 37.77. The NRC s NUREG-2155 provides helpful guidance on the implementation of security requirements. 

Although the nucleus of the uranium atom is relatively stable, it is radioactive, and will remain that way for many years. The half-life of U-238 is over 4.5 billion years the half-life of U-235 is over 700 million years. (Half-life refers to the amount of time it takes for one half of the radioactive material to undergo radioactive decay, turning into a more stable atom.) Because of uranium radiation, and to a lesser extent other radioactive elements such as radium and radon, uranium mineral deposits emit a finite quantity of radiation that require precautions to protect workers at the mining site. Gamma radiation is the... 

The laboratory operator must make a careful examination of all wastes that will be generated and, from this, work up a waste disposal system. Some wastes may be compatible and could be disposed of together. Others could react and thus cause problems. Flammables must be given special attention. Certain biological wastes may be very hazardous even in small quantities. Special rules apply to radioactive materials, even in the small amounts used for investigative purposes. 

It is important to note that since the amounts of radioactive material produced are so extremely small (some 10 % of the total is typical) it is usually necessary to add macro quantities—10-100 mg—of each compound expected to be present, in order to effect a good separation and to measure the chemical yield of the carrier. The yield measured is the radioactivity in each separated chemical species as a fraction of the total radioactivity in the sample, corrected to 100% chemical yield of each respective carrier. The term retention is commonly used to refer to the yield of the parent compound. This term has the disadvantage, however, of implying that the radioactive atom remained in the same molecule. Since it often appears that the molecule is only later reconstituted, the terms yield and parent yield are to be preferred. 

The level of radioactivity encountered in the usual radioimmunoassay procedures is low enough so that liquid wastes may be disposed of in the sink with running water. In calculating the amount of radioactive material that may be disposed of via the sewage system from one building, one must know the water usage. This may be obtained from the water bill. The allowable quantity of in sewage is 4.0 x 10" /ii Ci/ml of water... 

Quantity of radioactive material requiring need for an emergency plan for responding to a release—241 Am, 242Am, and 243Am Release fraction Quantity 0.001% 2 Ci NRC 2001 h 10CFR30.72, Schedule C... 

Quantities of radioactive material for signs, labels, and signals... 

Becquerel (Bq)—International System of Units unit of activity and equals that quantity of radioactive material in which one transformation (disintegration) occurs per second (see Units). 

Curie (Ci)—A unit of radioactivity. One curie equals that quantity of radioactive material in which there are 3.7xl010 nuclear transformations per second. The activity of 1 gram of radium is approximately 1 Ci. 

The activity is a measure of the quantity of radioactive material. For these radioactive materials it is customary to describe the activity as the number of disintegrations (transformations) per unit time. The unit of activity is the curie (Ci), which was originally related to the activity of one gram of radium, but is now defined as that quantity of radioactive material in which there are ... 

The SI unit of activity is the becquerel (Bq) 1 Bq = that quantity of radioactive material in which there is 1 transformation/second. Since activity is proportional to the number of atoms of the radioactive material, the quantity of any radioactive material is usually expressed in curies, regardless of its purity or concentration. The transformation of radioactive nuclei is a random process, and the number of transformations is directly proportional to the number of radioactive atoms present. For any pure radioactive substance, the rate of decay is usually described by its radiological half-life, TR, i.e., the time it... 

The radiation emitted by radioactive materials is harmful to living matter. Small quantities of radioactive isotopes are used in the process industry for various purposes for example, in level and density-measuring instruments, and for the non-destructive testing of equipment. 

The quantities of radioactive material created and, more particularly the impurities, are extremely small on the normal chemical scale, being somewhere between to-10 and 10-17 grammes. With such quantities normal precipitation methods may introduce difficulties due to non-selective adsorption, and other chemical techniques have been used to solve the separation problems of this micro-micro-chemistry. 

The most widely used technique for the separation of large quantities of radioactive material is that of solvent extraction. The principle of the method is that ideally the partition coefficient of a compound between two solvents does not depend on concentration in a given set of conditions. This was shown in an early paper of Graham and Sea-borg (35) who demonstrated that the partition coefficients of gallium and cobalt chlorides between ether and aqueous hydrochloric acid were the same for concentrations of lCTli molar (i. e. no added carrier) as for 1-6xl0 s molar. 

The separation of small amounts of radioactive material by the use of ion exchange resins is one of the most useful and flexible of separation methods, and one which can be readily adapted to remote control when large amounts of radioactive material are to be handled. The limit of the quantity will be reached when the resin decomposes under the action... 

Measurements of the quantities of glycolipids inserted into the membrane have also been reported by a technique based on the use of C-labeled lipid anchors. In this method, the carbohydrate (a-o-Man) was covalently coupled to the anchor at the surface of a pre-formed vesicle. Indeed, the liposome structure was shown to remain intact in the treatment. Nevertheless, the measurement of the incorporated mannose was performed after separation of bound and unbound material by centrifugation. The yields of coupling were shown to increase with the increase of the initial mannose/ C-anchor ratio, but non covalent insertions were displayed at high initial mannose concentrations. Therefore, the aforementioned method was not as accurate as could have been expected for the use of radioactive materials [142]. Radiolabeled phospholipids were also used for such determinations thus the amounts of glycosphingolipids incorporated into liposomes were quantified by the use of H-phospholipids whereas the amounts of glycolipids were determined by a sphingosine assay [143]. 

While he was investigating radioactive isotopes with Ernest Rutherford in 1913, George de Hevesy had an idea. Nuclear scientists were commonly forced to work with only tiny quantities of radioactive material, which would be very difficult to see using standard techniques of chemical analysis. But every single atom of a radioisotope advertised its presence when it decayed, since the radiation could be detected with a Geiger counter. So, if a... 

The conventional unit of radioactivity, the curie (Ci), is equivalait to 3.7 X 10 radioactive events per second. The SI unit used for denoting the amount of radioactive material contained in a given sample of matter is the becquerel (Bq) one becquerel is that quantity of a radioactive nuclide in which there is one radioactive event per second (1 Bq = 2.7 x 10 Ci). Since radionuclides decay exponentially with time, each element at its own rate, the time required for a given quantity of a radionuclide to lose one-half of its radioactivity is call its physical half-Ufe. 

The dose of radiation delivered by an internally deposited radionuclide depends on the quantity of radioactive material residing in situ. This quantity decreases as a function of the physical half-life of the radionuclide and the rate at which the element is redistributed or excreted (i.e., its biological half-life). Because the physical half-life is known precisely and the biological half-life can be characterized within limits for most radionuclides, the dose to a tissue that will ultimately be delivered by a given concentration of a radionuclide deposited therein can be predicted to a first approximation. The collective dose to a population that will be delivered by the radionuclide—the so-called collective dose commitment—serves as the basis for assessing the relevant long-term health effects of the nuclide. 

With equal quantities of material, which gives a higher counting rate on a radiation detector, radioactive material that has a short half-life or radioactive material that has a long half-life ... 

Coal contains only minute quantities of radioactive materials, and yet there is more environmental... 

Along with the unique sensitivity and small quantities of material associated with radiochemistry, there is the need to comply with the regulations governing the safe use and handling of radioactive material. This task is a primary focus in the design and execution of radiochemical experiments and is often a significant factor in the cost of the experiment. Because so many of these rules are site specific, they are not treated in this chapter. 

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