Measuring Radiation Exposure

For the monitoring of personnel radiation exposures, measurement of radioactive contamination and surveying of laboratories and equipment, and for the detection of radionuclides incorporated in the human body, various detectors and instruments are used. The principles of operation of these detectors have been discussed in the previous sections of this chapter. 

Knowledge about the radiations from each isotope is important because as the uses of the radioisotopes have iacreased, it has become necessary to develop sensitive and accurate detection methods designed to determine both the presence of these materials and the amount present. These measurements determine the amount of radiation exposure of the human body or how much of the isotope is present ia various places ia the environment. For a discussion of detection methods used see References 1 and 2. 

The ineident eommander may rely on visual observation of plae-ards, labels, and manifests and information gathered during the response. Obtaining air measurements with monitoring equipment for toxie eon-eentrations of vapors, partieulates, explosive potential, and the possibility of radiation exposure is important for determining the nature, degree, and extent of the hazards [2]. 

Answer The automobile death rate is about lE-7/passenger mile. If 25,000 people evacuate 20 miles, this is 5E5 passenger miles, hence, the risk is 5E5 IE-7 = 0.05 deaths. The radiation exposure is 2.5E4 5E-4 48 = 600 person-rem. Using information from problem 4, the estimated deaths from radiation is 600 lE-4 = 0.06. About the same. The risk from radiation may be over estimated because the radiation level was measured close to the plant on the other hand, the traffic fatality estimate may be high because of police presence and slow driving. 

Many states in the U.S. are currently involved in large scale surveys to measure radon levels in homes in an attempt to assess the environmental risk from radon and radon daughter exposure. Radon daughters deliver the largest radiation exposure to the population and it is estimated that 0.01% of the U.S. population (23,000 persons) are exposed from natural sources to greater than those levels allowed occupationally (4 WLM/yr) (NCRP, 1984). 

McCloskey, J.T. and T.T. Oris. 1993. Effect of anthracene and solar ultraviolet radiation exposure on gill ATPase and selected hematologic measurements in the bluegill sunfish (Lepomis macrochirus). Aquat. Toxicol. 24 207-218. 

Tests of a graphite-reinforced polyimide composite (C6000/PMR15) did not show any effect of radiation exposure (1 MEV electrons 6x109 rad total dose) on the thermal expansion behavior (14). DMA curves for unirradiated and irradiated composites were essentially identical over the temperature range of the thermal expansion measurements. 

The effect of radiation on the thermal expansion of this toughened composite (T300/CE 339) is shown (191 in Figure 24. The thermal strains measured during the cool-down portion of the first thermal cycle (cooling from RT to -150°C) are shown for the baseline composite (no radiation exposure) and for samples exposed to total doses as high as 10 0 rads. Radiation levels, as low as 10 rads... 

PTFE, FEP and PEA are sensitive to high-energy radiation. Exposure to 1 Mrad can lead to a measurable degradation. 

National Council on Radiation Protection and Measurement. 1987. Ionizing Radiation Exposure of the Population of the United States, Report 91. Bethesda, Md. National Council on Radiation Protection and Measurement. 

Quality Assurance and Measurement in Diagnostic Radiology Radiation Exposure and Potentially Related Injury Radiation Received in the Decontamination of Nuclear Facilities Guidance on Radiation Received in Space Activities Effects of Radiation on the Embryo-Fetus... 

Roentgen (R) The unit of radiation exposure in the air units for quantities of X-ray or gamma radiation measured by detection and survey meters. Named after Wilhelm Roentgen, German scientist who discovered X-rays in 1895. 

Radiation Personnel Accident. Radiation exposure in accidents of personnel in nuclear facilities and non-destructive detection have been evaluated with ESR dosimetry. For example, the amputated medium fibre bone of a worker in Peru, who tried to solve the problem by directly touching the source of 60Co unit for a few seconds, was measured four years later.The dose was measured by 6.4 + 0.5 Gy, while 20 + 3 Gy was obtained from fluorescence in situ hybridization method. The result would suggest diagenic decay of the signal due to the metabolism of bone.96 Thus, ESR gives the retrospective dose for radiation accidents. 

T he radioactive products of a nuclear explosion are said to have under-gone fractionation if their relative proportions in samples taken at various locations differ significantly from their relative proportions as formed. This report describes a study of fractionation in the early fallout from the nuclear cratering shots Danny Boy, Sedan, and Palanquin. Published fallout data for these shots was the basic information used in the study. A normalization procedure was applied to the published data as follows the amount of each radionuclide (or mass chain) of interest measured on a fallout tray is related to the gamma-radiation exposure rate measured at the tray location and to the amount of that radionuclide produced per kiloton of fission by the device. The result is an index... 

UCL takes into account measurement uncertainty in the study used to estimate the dose-response relationship, such as the statistical uncertainty in the number of tumors at each administered dose, but it does not take into account other uncertainties, such as the relevance of animal data to humans. It is important to emphasize that UCL gives an indication of how well the model fits the data at the high doses where data are available, but it does not indicate how well the model reflects the true response at low doses. The reason for this is that the bounding procedure used is highly conservative. Use of UCL has become a routine practice in dose-response assessments for chemicals that cause stochastic effects even though a best estimate (MLE) also is available (Crump, 1996 Crump et al., 1976). Occasionally, EPA will use MLE of the dose-response relationship obtained from the model if human epidemiologic data, rather than animal data, are used to estimate risks at low doses. MLEs have been used nearly universally in estimating stochastic responses due to radiation exposure. 

Measures of Radiation-Induced Responses. This Section discusses the measures of response from radiation exposure generally used in radiation protection and assessments of radiation risk in general terms. 

NCRP (1987c). National Council on Radiation Protection and Measurements. Radiation Exposure of the U.S. Population from Consumer Products and Miscellaneous Sources, NCRP Report No. 95 (National Council on Radiation Protection and Measurements, Bethesda, Maryland). 

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