b'P ROVING THE P RINCIPLEInterim storage Manhattan Engineer Natural uraniumA concept in the management of nuclear District/Manhattan Project Uranium that has not been through anwaste in which the waste is moved to an Created by President Roosevelt in 1939, the enrichment process to separate its urani-intermediary location between its point of Manhattan Engineer District of the U.S. um-235 isotopes. It is made of uranium-origin and its final or ultimate storage Army Corps of Engineers was commis- 238 (99.3 percent) and uranium-235 (0.7location. sioned to build an atomic bomb. The eff o r t percent).Iodine-131 was referred to as the Manhattan Project. NeutronAlso called radioiodine or radioactive Maximum permissible dose An uncharged particle, a part of an atom-iodine, an isotope of the element iodine, Aregulatory limit on the radiation expo- ic nucleus, having a mass nearly equal towhich has a half-life of about eight days. sure that a nuclear worker or a member that of a proton. One or more neutronsThis (and other iodine isotopes) are of the general public may legally receive are present in every known elementreleased when the cladding surrounding due to radioactive releases from a nuclear except hydrogen.spent fuel is dissolved or breached. power plant or other nuclear activity. Noble gasesIon exchange Megawatt Elemental gases which do not generallyA chemical process in which a substance A measure of electrical power equal to combine chemically with other materials.dissolved in water is exchanged with one million watts. They are helium, neon, argon, krypton,another. Meltdown xenon, and radon.Ionization chamber The accidental melting of nuclear reactor Nuclear power plantA device used to measure radioactivity. fuel caused by a failure of the coolant to An electrical generating facility usingIrradiate carry away heat.nuclear fuel.To expose a substance to ionizing radia- Millirem Nuclear energytion in a nuclear reactor. The substance so A unit of radiation equal to one thou- Energy released in a nuclear fission orexposed may be referred to as the target. sandth of a rem. See rem. fusion reaction.Isotope Microcurie Nuclear reactorAny of two or more species of atoms of a A measure of radioactivity equal to one A complex device designed to contain achemical element distinguished by differ- millionth of a curie. controlled nuclear fission chain reaction.ent quantities of neutrons in their nuclei. Mixed waste A reactor may function for testing andFor example, hydrogen has three iso- experimentation (Materials Test Reactor),topes: protium (one proton), deuterium Waste that contains both chemically haz- for the generation of electricity (any com-(two protons), and tritium (three protons). ardous and radioactive waste.mercial nuclear power plant), for the pro-Linear accelerator Moderator duction of weapons-related materialssuch as tritium or plutonium (N ReactorAdevice in which charged particles are Amaterial used in a nuclear reactor to at Hanford), as a breeder of nuclear fuelspeeded up in a straight line by successive reduce the natural speed of neutrons (Experimental Breeder Reactor), forimpulses from a series of electric fields. ejected from fissioning atoms. Typical propulsion (Submarine Thermal Reactor),moderators are water or graphite. or as a combination of these functions.310'