Exposure control, radiation neutron

X rays are encountered in chemistry labs where X-ray diffraction analysis is performed or in the technique of X-ray fluorescence (XRF). There are devices associated with these instruments that protect users from exposure to beams of X rays and it is important to be mindful of these devices. Neutron radiation is encountered in instruments that measure neutron scattering or diffraction or in neutron activation analysis. The level of hazard is associated with the energy (velocity) of the neutrons. Ordinarily, the use of neutrons is tied to the availability of a nuclear reactor, where controlled fission can produce a stream of neutrons. 

A special case of radiological effects of uranium is when a criticality incident occurs. A criticality accident, or an uncontrolled nuclear chain reaction, may inadvertently occur if a sufficient amount of accumulates under certain conditions. The criteria for criticality control are known by the acronym MAGIC MF.RV for Mass, Absorption, Geometry, Interaction, Concentration, Moderation, Enrichment, Reflection, and Volume (for more details, see Frame 1.3 in Chapter 1). The result would be the emission of neutrons and ganuna radiation, as occurred in Tokai-Mura, Japan, in 1999, and resulted in the death of two of the plant employees (WNA 2007). A brief discussion on the units for measuring radiation and exposure of the public is presented in Frame 4.3. 

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