Sources of radiation

The following are examples of possible radiation sources in a research reactor  

Solid and liquid radioactive waste and material arising from the treatment of radioactive waste  

Experimental facilities with the potential to generate activated material or other radioactive material  

Tools and facilities for the storage and handling of radioactive material, including sample activation and/or irradiation facUities, in-core experiments, beam ports and hot cells  

Neutron detectors (particularly fission chambers and self-powered neutron detectors)  

Intensities, energies, and special characteristics of the various radiation sources are briefly discussed in this section. 

The magnitudes, locations, possible transport mechanisms and transport routes of the sources of potential radiation exposure under accident conditions should also be determined in the design phase of the plant. Guidance on the safety analysis to be carried out during the development of the design and for the final assessment is given in Ref. [10]. 

The main source of radiation under accident conditions for which precautionary design measures should be adopted consists of radioactive fission products. These are released either from the fuel elements or from the various systems and equipment in which they are normally retained. In Annex III examples of methods for assessing radiation sources for selected accidents are described. The scenarios are selected for illustrative purposes and cover all the major categories of designs for nuclear power plants with LWRs, CO2 cooled reactors with UOj metal clad fuel, HWRs and reactors with on-load refuelling. 

More specifically, an optimization culture should be established on the basis of  

Specialists in radiation protection should be closely involved in the design process because of their  

Because chemical parameters are very important in controlling the radioactive sources in the plant, specialists in radiochemistry should also be involved in the design process. Materials speciaUsts should be involved in controlling the source term due to corrosion products. 

Care should be taken to prevent undue (or indeed any) absorption of radiation by the operator, especially by the eyes and particularly with laser sources. The range of wavelengths of radiation for photochemical reactions extends from 1200 A to 7000 A. When studying photochemical reactions it is particularly useful to be able to convert wavelength Q3) in A to energy ( )inkcal. Einstein . This is given by the expression 

The wavelength range is divided into several sections which are shown in Table 4. As far as this discussion of sources is concerned, the range is divided into two the vacuum uv region is treated separately. 

The most common sources of radiation for kinetic photochemical studies are mercury lamps of which there are three types. The low-pressure lamp is used mainly for mercury-sensitised studies. For general photochemical studies the most useful lamp is the medium-pressure lamp having several lines of reasonable 

S is the total spin quantum number =. . ., L is the total angular mo- 

Low-pressure lamps. These lamps operate at or close to room temperature. This means that the vapour pressure of Hg is 10 torr. In addition to mercury about 6 torr of inert gas, usually neon, is added. This makes for easy firing but there is some evidence that a higher intensity is produced due to reaction (13). 

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The source of radiation is a linear accelerator with selectable primary energies of 6, 9 or 11 MeV ( VARIAN Linatron 3000 A). The output of the LINAC at 9 MV is 3000 rad ( 30 Gy) per minute. The pulse length is 3.8 microseconds with repetition frequencies between 50 and 250 Hertz. 

The control technique of fuel distribution in uranium - graphite fiael elements seems to be most perform. The technique allows to determine weight of uranium or its connections in a chosen zone of fuel elements. There were used the sources of radiation on a basis radionuclide Am. The weight of uranium in fuel element or its parts is determined by combine processing of a tomograms, set received on several parallel layers of fuel element. The comparative results of tomographic researches and chemical analysis of weight of uranium in quarters of spherical fuel elements are resulted in the table. 

Radiation exits the monochromator and passes to the detector. As shown in Figure 10.12, a polychromatic source of radiation at the entrance slit is converted at the exit slit to a monochromatic source of finite effective bandwidth. The choice of... 

Equation 10.1 has an important consequence for atomic absorption. Because of the narrow line width for atomic absorption, a continuum source of radiation cannot be used. Even with a high-quality monochromator, the effective bandwidth for a continuum source is 100-1000 times greater than that for an atomic absorption line. As a result, little of the radiation from a continuum source is absorbed (Pq Pr), and the measured absorbance is effectively zero. Eor this reason, atomic absorption requires a line source. 

Turbidimetry and nephelometry are two related techniques in which an incident source of radiation is elastically scattered by a suspension of colloidal particles. In turbidimetry, the detector is placed in line with the radiation source, and the... 

Description of Method. Adding BaC to an acidified sample precipitates S04 a BaS04. The concentration of S04 may be determined either by turbidimetry or nephelometry using an incident source of radiation of 420 nm. External standards containing known concentrations of S04 are used to standardize the method. 

Better detection limits are obtained using fluorescence, particularly when using a laser as an excitation source. When using fluorescence detection, a small portion of the capillary s protective coating is removed and the laser beam is focused on the inner portion of the capillary tubing. Emission is measured at an angle of 90° to the laser. Because the laser provides an intense source of radiation that can be focused to a narrow spot, detection limits are as low as 10 M. 

Sources of radiation are all of lower than ideal intensity. One of the most commonly used is a mercury discharge in a quartz envelope, most of the higher-wavenumber radiation coming from the quartz rather than from the discharge plasma. 

Laser radiation is emitted entirely by the process of stimulated emission, unlike the more conventional sources of radiation discussed in Chapter 3, which emit through a spontaneous process. 

Both the a-X and b-X transitions have long been known from absorption by the oxygen in the earth s atmosphere, the source of radiation being the sun and the very long path length of oxygen overcoming their extreme weakness. For laboratory observation of these transitions, and particularly for accurate determination of absolute absorption intensity, CRDS has proved to be an ideal technique. 

Radiation. Protection against high voltage and fixed isotope sources of radiation is usually a matter of shielding and the observance of strict... 

Because NEP is roughly proportional to D is more useful for comparing detectors of differing sizes. D depends on the wavelength distribution striking the detector (if it is quantum) and the frequency at which the radiation is modulated, so these measurement parameters need to be included for a D value to have meaning. Often detectivity is written as where Tis the temperature of the blackbody source of radiation or the wavelength of the... 

The use of inadiation or electron bombardment offers an alternative approach to molecular dissociation to the use of elevated temperamres, and offers a number of practical advantages. Intensive sources of radiation in the visible and near-visible are produced by flash photolysis, in which a bank of electrical capacitors is discharged tlrrough an inert gas such as ktypton to produce up to 10 joule for a period of about 10 " s, or by the use of high power laser beams (Eastham, 1986 (loc.cit.)). A more sustainable source of radiation is obtained from electrical discharge devices usually incorporating... 

The attenuation factor for a receptor at the center of a finite plane uniform source of radiation is given by equation 8.3-7, where b is the radius and z is the height of the receptor above the plane. If there is... 

Spectrometers are designed to measure the absorption of electromagnetic radiation by a sample. Basically, a spectrometer consists of a source of radiation, a compartment containing the sfflnple through which the radiation passes, and a detector. The frequency of radiation is continuously varied, and its intensity at the detector is compar ed with that at the source. When the frequency is reached at which the sample absorbs radiation, the detector senses a decrease in intensity. The relation between frequency and absorption is plotted as a spectrum, which consists of a series of peaks at characteristic frequencies. Its interpretation can furnish structural information. Each type of spectroscopy developed independently of the others, and so the data format is different for each one. An NMR spectrum looks different from an IR spectrum, and both look different from a UV-VIS spectrum. 

In spectrophotometric analysis a source of radiation is used that extends into the ultraviolet region of the spectrum. From this, definite wavelengths of radiation are chosen possessing a bandwidth of less than 1 nm. This process necessitates the use of a more complicated and consequently more expensive instrument. The instrument employed for this purpose is a spectrophotometer. 

The lines in the spectrum from any element always occur in the same positions relative to each other. When sufficient amounts of several elements are present in the source of radiation, each emits its characteristic spectrum this is the basis for qualitative analysis by the spectrochemical method. It is not necessary to examine and identify all the lines in the spectrum, because the strongest lines will be present in definite positions, and they serve to identify unequivocally the presence of the corresponding element. As the quantity of the element in the source is reduced, these lines are the last to disappear from the spectrum they have therefore been called the persistent lines or the rates ultimes (R.U. lines), and simplify greatly the qualitative examination of spectra. 

Thru 1967, emphasis was given to the use of neutrons as the bombarding source of radiation. Almost all possible neutron reactions were considered including moderation of fast neutrons by hydrogen in the expl, thermal capture reactions, elastic and inelastic scattering of neutrons and neutron activation reactions. These neutron reactions are listed as follows ... 

The control of ionizing radiation is heavily regulated. Expert advice should be sought prior to introducing sources of radiation on to the premises. The general provisos for their control are that ... 

Like many of the topics discussed in this book, photochemical reactions are most likely to be used in niche applications for commercial and environmental reasons. Unless there is a major breakthrough in reactor and lamp design, widespread use of this technology is unlikely. Perhaps the best hope of producing high-intensity monochromatic sources of radiation rests with lasers, but currently equipment costs are too high to justify their use for commercial chemical production. 

FDA. 2000. Sources of radiation used for inspection of food-sealed units producing radiation. Food and Drug Administration, http //www.access.gpo.gov/cgi-bin/cfrassemble.cgi. March 14,2001. 

Attenuation—A process by which a beam from a source of radiation is reduced in intensity by absorption and scattering when passing through some material. 

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