Contamination, radiation

It is important to distinguish between radiation and radioactive contamination. Radiation is energy emitted by atoms that are unstable. Radiation travels through space to some extent—some kinds of radiation can only travel a few millimeters, whereas other types can travel for many meters. Radioactive contamination is the presence of radiation-emitting substances (radioactive materials or RAM) in a place where it is not desired. A patient may be contaminated with radioactive materials, but that patient will not be inherently radioactive and can be decontaminated. Radioactive materials, by comparison, are inherently radioactive—it is a physical property of that material in the same manner as mass or size—and they remain radioactive until they decay to stability. 

Were contamination/radiation levels measured on the patient s skin If so, what were the results ... 

EPA (1997b). Clarification of the Role of Applicable or Relevant and Appropriate Requirements in Establishing Preliminary Remediation Goals under CERCLA. OSWER No. 9200.4-23. Office of SoUd Waste and Emergency Response, US Environmental Protection Agency, Washington, D.C. Accessed at http //www.epa.gov/superfund/health/contaminants/radiation/pdfs/aras.pdf. 

Name the types of radiation that are particulate and create contamination. Radiation always travels in the following manner. 

Examples of derived limits in the Regulations include the maximum activity limits Aj and Aj, maximum levels for non-fixed contamination, radiation levels at the surfaces of packages and in their proximity, and segregation distances associated with the transport index. The Regulations reqnire assessment and measurement to ensure that standards are being complied with. 

CROSS, W.G., FREEDMAN, N.O., WONG, RY., Beta ray dose distributions from skin contamination, Radiat. Prot. Dosim. 40 3 (1992) 149-168. 

Threat Casualties Acute trauma Contamination Radiation dose (>0.5 Sv) Iodine Radiation type... 

The properties required by jet engines are linked to the combustion process particular to aviation engines. They must have an excellent cold behavior down to -50°C, a chemical composition which results in a low radiation flame that avoids carbon deposition on the walls, a low level of contaminants such as sediment, water and gums, in order to avoid problems during the airport storage and handling phase. 

Standardizing the Method Equations 10.32 and 10.33 show that the intensity of fluorescent or phosphorescent emission is proportional to the concentration of the photoluminescent species, provided that the absorbance of radiation from the excitation source (A = ebC) is less than approximately 0.01. Quantitative methods are usually standardized using a set of external standards. Calibration curves are linear over as much as four to six orders of magnitude for fluorescence and two to four orders of magnitude for phosphorescence. Calibration curves become nonlinear for high concentrations of the photoluminescent species at which the intensity of emission is given by equation 10.31. Nonlinearity also may be observed at low concentrations due to the presence of fluorescent or phosphorescent contaminants. As discussed earlier, the quantum efficiency for emission is sensitive to temperature and sample matrix, both of which must be controlled if external standards are to be used. In addition, emission intensity depends on the molar absorptivity of the photoluminescent species, which is sensitive to the sample matrix. 

Isolation of radioactive wastes for long periods to allow adequate decay is sought by the use of multiple barriers. These include the waste form itself, the primary containers made of resistant materials, overpacks as secondary layers, buffer materials, concrete vaults, and finally the host rock or sod. Barriers limit water access to the waste and minimize contamination of water suppHes. The length of time wastes must remain secure is dependent on the regulatory limit of the maximum radiation exposure of individuals in the vicinity of the disposal site. 

The accident at the Three Mile Island (TMI) plant in Pennsylvania in 1979 led to many safety and environmental improvements (4—6). No harm from radiation resulted to TMI workers, to the pubHc, or to the environment (7,8), although the accident caused the loss of a 2 x 10 investment. The accident at the Chernobyl plant in the Ukraine in 1986, on the other hand, caused the deaths of 31 workers from high doses of radiation, increased the chance of cancer later in life for thousands of people, and led to radioactive contamination of large areas. This latter accident was unique to Soviet-sponsored nuclear power. The Soviet-designed Chemobyl-type reactors did not have the intrinsic protection against a mnaway power excursion that is requited in the test of the world, not was there a containment building (9—11). 

Beyond the simple resistance of a material of construction to dissolution in a given chemical, many other properties enter into consideration when makiug an appropriate or optimum MOC selection for a given environmental exposure. These factors include the influence of velocity, impurities or contaminants, pH, stress, crevices, bimetallic couples, levels of nuclear, UV, or IB radiation, microorganisms, temperature heat flux, stray currents, properties associatea with original production of the material and its subsequent fabrication as an item of equipment, as well as other physical ana mechanical properties of the MOC, the Proverbial Siebert Changes in the Phase of the Moon, and so forth. 

Figure 14-9 also shows a flowchart for analysis of wet and dry precipitation. The process involves weight determinations, followed by pH and conductivity measurements, and finally chemical analysis for anions and cations. The pH measurements are made with a well-calibrated pH meter, with extreme care taken to avoid contaminating the sample. The metal ions Ca, Mg, Na, and are determined by flame photometry, which involves absorption of radiation by metal ions in a hot flame. Ammorda and the anions Cl, S04 , NO3 , and P04 are measured by automated colorimetric techniques. 

The term, metal dusting, was first used about this time to describe the phenomenon associated with hydrocarbon processing. Butane dehydrogenation plant personnel noted how iron oxide and coke radiated outward through catalyst particles from a metal contaminant which acted as a nucleating point. The metal had deteriorated and appeared to have turned to dust. The phenomenon has been called catastrophic carburization and metal deterioration in a high temperature carbonaceous environment, but the term most commonly used today is metal dusting. 

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