Radioactive materials radium

People have observed luminescence in nature for centuries, hi the early twentieth century, Marie Curie, in her doctoral thesis, mentioned that calcium fluoride glows when exposed to the radioactive material, radium, hi the past 50 years, the use of luminescent devices, such... 

Care must be taken in handling radon, as with other radioactive materials. The main hazard is from inhalation of the element and its solid daughters which are collected on dust in the air. Good ventilation should be provided where radium, thorium, or actinium is stored to prevent build-up of the element. Radon build-up is a health consideration in uranium mines. Recently radon build-up in homes has been a concern. Many deaths from lung cancer are caused by radon exposure. In the U.S. it is recommended that remedial action be taken if the air in homes exceeds 4 pCi/1. 

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... 

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 ... 

Activity The activity of a radioactive material is the number of nuclear disintegrations per unit time. Up to 1977, the accepted unit of activity was the curie (Ci), equivalent to 37 billion disintegrations/s, a number that approximated the activity of 1 g radium-226. The present unit of activity is the becquerel (Bq), equivalent to 1 disintegration/s. 

When thorium emits alpha particles, it disintegrates into other daughter radionuclides (radioactive materials), such as radium-226 and radon-222 (from thorium-230 in the uranium-238 decay series) or radium-228 and thoron (radon-220 from thorium-232 in the thorium decay series). It eventually decays to stable lead-208 or -206, which is not radioactive. More information about the decay of thorium can be found in Chapter 3. The toxicological characteristics of radon, radium, and lead are the subject of separate ATSDR Toxicological profiles. 

The Bq is a minute measure of radioactivity and any sizeable amount of radioactive material will contain very many atoms and thus emit considerable amounts (TBq or GBq) of radiation. Another popular unit of decay is the curie, a non-Sl unit (historically calculated from the disintegrations of radium) which is equivalent to 37 x 10 Bq. Importantly, radioactivity decays exponentially, where a population of atoms in a sample will have a characteristic half-life (fi/2). The half-life is the key parameter when considering radioactivity and associated safety of radioisotopes, where fi/2 represents the time taken for the radioactivity to fall to a half the recorded level, as illustrated in Figure 10.4. Half-lives and associated properties of common radioactive isotopes are given in Table 10.2. 

The significance of the uranium reactors as a source of radioactive material can be made clear by a comparison with the supply of radium now in use. About 1000 curies (1000 grams) of radium has been separated from its ores and put into use, mainly for medical treatment. The rate of operation mentioned above for the reactors at Hanford represents the fission of about 5 X 10- nuclei per second, forming about 10 X 10 radioactive atoms. The concentration of these radio-acti e atoms will build up until they are undergoing decomposition at tjie rate at which they, are being formed. Since 1 curie corresponds to 3.71 X 10 disintegrating atoms per second, these reactors develop a radioactivity of approximately 3 X 10 curies that is, about thirty million times the radioactivity of all the radium which has been so far isolated from its ores. 

The curie, abbreviated Ci, is a standard unit of radioactive decay. It was originally defined as the rate at which 1 g of radium decays. Because of the relatively long half-life of Ra, the isotope served as a convenient standard. The curie is now defined as the quantity of any radioactive substance in which the decay rate is 3.700 X 10 disintegrations per second (2.22 X 10 DPM). Because the efficiency of most radiation detection devices is less than 100%, a given number of curies almost always yields a lower than theoretical count rate. Hence, there is the distinction between DPM and CPM. For example, a sample containing 1 /rCi of radioactive material has a decay rate of 2.22 x lO DPM. If only 30% of the disintegrations are detected, the observed count rate is 6.66 X 10 CPM. 

Percy s Legacy Marguerite Percy made important discoveries during an era when few women held prominent roles in the sciences. She was interested in science even as a small child. However, her father died early on, and there was no money for Percy to attend a university. Instead, she found a job at the Radium Institute in Paris. The Radium Institute had been founded by Marie Curie (1867-1934) and her husband, Pierre Curie (1859-1906), to study radioactive materials. 

Over the next decade, many scientists worked to find out more about radioactive materials. Curie and her husband, Pierre Curie (1859-1906), isolated two new radioactive elements, polonium and radium. In 1900, German physicist Friedrich Ernst Dorn (1848-1916) found a third radioactive element radon. 

Some scientists believe that technetium will be found in very small amounts in Earth s crust along with other radioactive materials, such as uranium and radium. However, it has never been found on Earth. It has, however, been found in certain types of stars. Its presence can be detected by analyzing the light produced by these stars. 

The radioactive properties of radium are the greatest concern and overwhelm all else. All radioactive materials may cause harm when decay particles are released that disrupt many critical cell functions, including DNA replication. Radioactive materials may also produce toxicity not related to their radioactive behavior. Like barium compounds, radium... 

The name comes from the Latin radius, meaning ray. It was discovered by Marie and Pierre Curie in 1898 when they were studying uranium and other radioactive materials found in pitchblende. There is about 1 g of radium in 7 tons of pitchblende, but it is 3xl05 times more radioactive than uranium. It was isolated as a metallic element in 1911 by Marie Curie and Andre-Louis Debieme (1874-1949). Radium exists in small quantities associated with uranium ores. Radium is phosphorescent, so it has been used to make luminous paint, especially for watch dials, but, because it is highly radioactive, most uses are related to nuclear medicine or the energy industry. Radon gas is produced from radium and is a harmful by-product. 

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