Radiation hazard

Many processes and inspection procedures depend on radiation-emitting substances and equipment. Potential sources of exposure include radiographic examination of equipment smoke detectors using alpha-emitting radioisotopes radioisotopes used as tracers in fluid flow and biochemical analysis radiation-based level and density instruments microwave ovens industrial lasers 

TABLE 2-4 Parameters Used to Define and Monitor Radiation Hazards  

Relative Biological Effectiveness (RBE) of Common Types of Radiation  

Low energy beta, gamma, and X-rays, electrons (less than 0.03 MeV) 1  

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Unstable niobium isotopes that are produced in nuclear reactors or similar fission reactions have typical radiation hazards (see Radioisotopes). The metastable Nb, = 14 yr, decays by 0.03 MeV gamma emission to stable Nb Nb, = 35 d, a fission product of decays to stable Mo by... 

B31.7 Nuclear Power Piping For fluids whose loss from the system could cause radiation hazard to plant personnel or the general pubhc Withdrawn see ASME Boiler and Pressure Vessel Code, Sec. 3... 

Fireballs Giant hazardous fireballs result from large BLEX s. Several formulas for BLE physical parameters and thermal radiation hazards have been summarized by the Center for Chemical Process Safety (CCPS) of the American Institute of Chemical Engineers and by Pruffh. (See AlChE/CCPS, 1989 Prugh, 1994.) For the maximum fireball diameter, in meters, CCPS has selected... 

Effects of indoor air pollutants on humans are essentially the same as those described in Chapter 7. However, there can be some additional pollutant exposures in the indoor environment that are not common in the ambient setting. From the listing in Table 23-1, radon exposures indoors present a radiation hazard for the development of lung cancer. Environmental tobacco smoke has been found to cause lung cancer and other respiratory diseases. Biological agents such as molds and other toxins may be a more likely exposure hazard indoors than outside. 

The fireball resulting from ignition of a cloud of flammable vapor may be relatively long lasting (2-5 seconds), and represents a thermal radiation hazard to those close to the cloud CCPS (1994b). 

Are there any ehemieal, physieal, biologieal, or radiation hazards assoeiated with the job Are any of these hazards likely to develop ... 

Roberts, A. F., 1981, Thermal Radiation Hazards for Releases of LPG from Pressurized Storage, Fire Safety Journal 4, p 197-212. 

Mudan, K. S. 1984. Thermal radiation hazards from hydrocarbon pool fires. Prog. Energy Combust. Sci. 10 59-80. 

Roberts, A. F. 1982. Thermal radiation hazards from release of LPG fires from pressurized storage. Fire Safety J. 4 197-212. 

The literature provides little information on the effects of thermal radiation from flash fires, probably because thermal radiation hazards from burning vapor clouds are considered less significant than possible blast effects. Furthermore, flash combustion of a vapor cloud normally lasts no more than a few tens of seconds. Therefore, the total intercepted radiation by an object near a flash fire is substantially lower than in case of a pool fire. 

Four parameters often used to determine a fireball s thermal-radiation hazard are the mass of fuel involved and the fireball s diameter, duration, and thermal-emissive power. Radiation hazards can then be calculated from empirical relations. For detailed calculations, additional information is required, including a knowledge of the change in the fireball s diameter with time, its vertical rise, and variations in the fireball s emissive power over its lifetime. Experiments have been performed, mostly on a small scale, to investigate these parameters. The relationships obtained for each of these parameters through experimental investigation are presented in later sections of this chapter. 

A fireball s radiation hazard can be assessed by two factors its diameter (either as a function of time or original amount of fuel) and combustion duration. Fireball models presented by Lihou and Maund (1982), Roberts (1982), and others start with a hypothetical, premixed sphere of fuel and air (in some cases, oxidant) at ambient temperature. Because the molar volume of any gas at standard conditions... 

Raj, P. K. 1977. Calculation of thermal radiation hazards from LNG fires. A Review of the State of the Art, AGA Transmission Conference TI35-148. 

The radiation hazard from a BLEVE fireball can be estimated once the following fireball properties are known ... 

The following procedure can be followed for estimating radiation hazards ... 

You should be able to estimate the quantities of material contained within a section from mechanical and operating data. You should also consider operating conditions, which should be available from the plant mass balance or from actual operating data. Simple hazard models can predict the size of vapor clouds, radiation hazards from fires, and explosion over-pressures. Such models are available from a number of sources. 

The radiation hazard associated with fallout from nuclear weapons testing arises from radioactive isotopes such as these. One of the most dangerous is strontium-90. In the form of strontium carbonate, SrC03, it is incorporated into the bones of animals and human beings, where it remains far a lifetime. 

Ce02, Cm203, Tm203, Pu02. The radiation hazard and the costs involved eliminated all candidates but a 20% concn of Pu-238 or plutonium oxide... 

Droullard, R.F., T.H. Davis, E.E. Smith, and R.F. Holub, Radiation Hazard Test Facilities at Denver Research Center, Bureau of Mines IC 8965 1-22 (1984). 

S. Wood and R. Mick, Age Factor in Histological Type of Lung Cancer in Uranium Miners, a Preliminary Report, in Radiation Hazards in Mining (M. Gomez, ed) pp. 675-679, Society of Mining Engineers, New York (1982). 

Several limitations on the synthetic techniques that can be employed are imposed by the need for rapidity and minimization of handling because of the radiation hazard, and the low concentration and small physical quantities of the compounds. Purification steps should be eliminated if possible by optimizing yields. Where purification is unavoidable, simple procedures are employed such as use of anion exchange columns to remove perrhenate (the most common contaminant in the final product). A variety of disposable sample preparation columns are well suited to this purpose and are available containing small quantities of anion or cation exchange materials (0.1 to 0.5 g typically) such as quaternary ammonium-, primary ammonium-, or sulfonate-derivatized silica. Reversed phase columns are also often used (C8 or C18-derivatized silica). The purification is often thus reduced to a simple filtration step which can be performed aseptically. 

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