62 Radioactive Materials Safety Manual Environmental Health and Safety in much the same way heat is used to stimulate luminscence in a thermoluminescent dosimetry (TLD) badge. The light output is then related to the badge‘s radiation dose. Member of the Public – an individual , except when that individual is receiving an occupational dose. Microcurie (µCi) – a one-millionth part of a curie. (1/1,000,000), (.000001 Ci), (see curie) Millicurie (mCi) – a one-thousandth of a curie. (1/1000), (.001 Ci), (see curie) MilliRoentgen (mR) – a sub-multiple of the Roentgen equal to one-thousandth (1/1000) of a Roentgen. (see Roentgen) Monitoring – the measurement of radiation levels, concentrations, surface area concentrations or quantities of radioactive material and the use of the results of these measurements to evaluate potential exposures and doses. NARM – accelerator-produced radioactive material. It does not include by-product, source, or special nuclear material. Natural Radiation – ionizing radiation, not from man-made sources, arising from radioactive material other than the one directly under consideration. Natural radiation due to cosmic rays, soil, natural radiation in the human body and other sources of natural radioactivity are always present. The levels of the natural radiation vary with location, weather patterns and time to some degree. Neutron – elementary particle with a mass approximately the same as that of a hydrogen atom and electrically neutral. It has a half-life in minutes and decays in a free state into a proton and an electron. Non-Removable Contamination – contamination adhering to the surface of structures, areas, objects or personnel and will not readily be picked up or wiped up by physical or mechanical means during the course of a survey or during decontamination efforts. Nuclear Density Gauge – a testing device, usually fixed in place and non-mobile, containing at least one sealed source of radioactive material, used to measure the density and composition of the test material. Nuclear Regulatory Commission (NRC) – an independent federal regulatory agency responsible for licensing and inspecting nuclear power plants, universities and other facilities using radioactive materials. Nucleus – the small, central, positively charged region of an atom that carries essentially all the mass. Except for the nucleus of ordinary (light) hydrogen, which has a single proton, all atomic nuclei contain both protons and neutrons. The number of protons determines the total positive charge, or atomic number; this is the same for all the atomic nuclei of a given chemical element. The total number of neutrons and protons is called the mass number. Nuclide – a species of atom characterized by its mass number, atomic number, and energy state of its nucleus, provided that the atom is capable of existing for a measurable time. Occupational Dose – the dose received by an individual in the course of employment in which the individual‘s assigned duties involve exposure to radiation and to radioactive material from licensed and unlicensed sources of radiation, whether in the possession of the licensee or other person. Occupational dose does not include dose received from background radiation, as a patient from medical practices, from voluntary participation in medical research programs, or as a member of the general public. Photon – a quantum (or packet) of energy emitted in the form of electromagnetic radiation. Gamma rays and X-rays are examples of photons. Pig – a container (usually lead) used to ship or store radioactive materials. The thick walls protect the person handling the container from radiation. Large containers are commonly called casks. Portable Gauge – an evaluation device containing at least one sealed source of radioactive material that can be transported or carried to a test location. See Nuclear Density Gauge. Positron – particle equal in mass, but opposite in charge, to the electron; a positive charge.