64 Radioactive Materials Safety Manual Environmental Health and Safety Seivert – the SI unit of any of the quantities expressed as dose equivalent. The dose equivalent in Seivert is equal to the absorbed dose in Gray multiplied by the quality factor. (1 Sv = 100 rem) Shallow Dose Equivalent – applies to the external exposure of the skin or an extremity and is taken as the dose equivalent at a tissue depth of 0.007 centimeter (7 mg/cm2 ) averaged over an area of one square centimeter. Shielding Material – any material which is used to absorb radiation and thus effectively reduce the intensity of radiation, and in some cases eliminate it. Lead, concrete, aluminum, water and plastic are examples of commonly used shielding material. Site Boundary – that line beyond which the land or property is not owned, leased, or otherwise controlled by the licensee. Smear – (smear or swipe test) a procedure in which a swab, e.g., filter paper or cotton tipped applicator, is rubbed on a surface and its radioactivity measured to determine if the surface is contaminated with loose (removable) radioactive material. Specific Activity – total radioactivity of a given nuclide per gram of a compound, element or radioactive nuclide. Stable Isotope – a radionuclide that does not undergo radioactive decay. Survey an evaluation of the radiological conditions and potential hazards incident to the production, use, transfer, release, disposal or presence of radioactive material or other sources of radiation. When appropriate, such an evaluation includes a physical survey of the location of radioactive material and measurements or calculations of levels of radiation, or concentrations or quantities of radioactive material present. Stochastic Health Effects – random radiation effects (those that would be observable after a long period of time) that is dependent upon the radiation dose. Survey – an evaluation of the radiological conditions and potential hazards incident to the use, transfer disposal, or presence of sources of radiation. This evaluation includes a physical survey of the location of radioactive material and measurements of levels of radiation or quantities of radioactive material present. Thermoluminescent Dosimeter (TLD) – crystalline materials that emit light if they are heated after being they have been exposed to radiation. Total Effective Dose Equivalent – the sum of the deep dose equivalent (for external exposures) and the committed effective dose equivalent (for internal exposures). Tracer, Isotopic – the radionuclide or non natural mixture of radionuclides of an element which may be incorporated into a sample to make possible observation of the course of that element, alone or in combination, through a chemical, biological, or physical process. The observations may be made by measurement of radioactivity or of isotopic abundance. Unrestricted Area – an area, access to which is neither limited nor controlled by the licensee. Unstable Isotope – a radionuclide. Very High Radiation Area – an area accessible to individuals, in which radiation levels could result in an individual receiving an absorbed dose in excess of 500 rads (5 grays) in one hour at one meter from a source of radiation or from any surface that the radiation penetrates. X-rays – penetrating electromagnetic radiation having wave lengths shorter than those of visible light. They are usually produced by bombarding a metallic target with fast electrons in a high vacuum. In nuclear reactions it is customary to refer to photons originating in the nucleus as gamma rays, and those originating in the extranuclear part of the atom as X-rays. These rays are sometimes called Roentgen rays after their discoverer, W.C. Roentgen.