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Science Terms Definitions - N

NARM Wastes (Naturally-Occurring and Accelerator-Produced Radioactive Materials) - are orphan wastes not consistently regulated under any current federal standard. NARM includes such materials as radium-226 and thorium-230 produced outside the nuclear fuel-cycle, and radio nuclides produced by particle accelerators. NARM wastes are generated by both federal and non-federal facilities.

National Ambient Air Quality Standards (NAAQS) - Standards established by EPA that apply for outside air throughout the country. (See: criteria pollutants, state implementation plans, emissions trading.)

National Emissions Standards For Hazardous Air Pollutants (NESHAPS) - Emissions standards set by EPA for an air pollutant not covered by NAAQS that may cause an increase in fatalities or in serious, irreversible, or incapacitating illness. Primary standards are designed to protect human health, secondary standards to protect public welfare (e.g., building facades, visibility, crops, and domestic animals).

National Estuary Program - A program established under the Clean Water Act Amendments of 1987 to develop and implement conservation and management plans for protecting estuaries and restoring and maintaining their chemical, physical, and biological integrity, as well as controlling point and nonpoint pollution sources.

National Interim Primary Drinking Water Regulations - Commonly referred to as NIPDWRs.

National Municipal Plan - A policy created in 1984 by EPA and the states to bring all publicly owned treatment works (POTWs) into compliance with Clean Water Act requirements.

National Oil and Hazardous Substances Contingency Plan (NOHSCP/NCP) - The federal regulation that guides determination of the sites to be corrected under both the Superfund program and the program to prevent or control spills into surface waters or elsewhere.

National Pollutant Discharge Elimination System (NPDES) - A provision of the Clean Water Act which prohibits discharge of pollutants into waters of the United States unless a special permit is issued by EPA, a state, or, where delegated, a tribal government on an Indian reservation.

National Priorities List (NPL) - EPA's list of the most serious uncontrolled or abandoned hazardous waste sites identified for possible long-term remedial action under Superfund. The list is based primarily on the score a site receives from the Hazard Ranking System. EPA is required to update the NPL at least once a year. A site must be on the NPL to receive money from the Trust Fund for remedial action.

National Response Center - The federal operations center that receives notifications of all releases of oil and hazardous substances into the environment; open 24 hours a day, is operated by the U.S. Coast Guard, which evaluates all reports and notifies the appropriate agency.

National Response Team (NRT) - Representatives of 13 federal agencies that, as a team, coordinate federal responses to nationally significant incidents of pollution, oil spill, a major chemical release, or a Superfund response action and provide advice and technical assistance to the responding agency(ies) before and during a response action.

National Secondary Drinking Water Regulations - Commonly referred to as NSDWRs.

Natural Uranium - Uranium as found in nature. It contains 0.7 percent uranium-235, 99.3 percent uranium-238, and a trace of uranium-234.

Naturally Occurring Radioactive Materials (NORM) - NORM is a subset of NARM and refers to materials not covered under the Atomic Energy Act whose radioactivity has been enhanced (radionuclide concentrations are either increased or redistributed where they are more likely to cause exposure to man) usually by mineral extraction or processing activities. Examples are exploration and production wastes from the oil and natural gas industry and phosphate slag piles from the phosphate mining industry. This term is not used to describe or discuss the natural radioactivity of rocks and soils, or background radiation, but instead refers to materials whose radioactivity is technologically enhanced by controllable practices.

Navigable Waters - Traditionally, waters sufficiently deep and wide for navigation by all, or specified vessels; such waters in the United States come under federal jurisdiction and are protected by certain provisions of the Clean Water Act.

Neoplasm - An aberrant new growth of abnormal cells or tissue in which the growth is uncontrollable and progressive.

Neutron - An elementary particle slightly heavier than a proton, with no electric charge.

NIOSH - National Institute for Occupational Safety and Health of the Public Health Service, U.S. Department of Health and Human Services (DHHS). A federal agency which, among other activities, tests and certifies respiratory protective devices and air sampling detector tubes, recommends occupational exposure limits for various substances and assists OSHA and MSHA in occupational safety and health investigations and research.

No Further Remedial Action Planned - Determination made by EPA following a preliminary assessment that a site does not pose a significant risk and so requires no further activity under CERCLA.

No Observable Adverse Effect Level (NOAEL) - From long-term toxicological studies of agriculture chemical active ingredients, levels at which indicate a safe, lifetime exposure level for a given chemical. Used to establish tolerance for human diets. Also written, NOEL.

Non-potable - Water that is unsafe or unpalatable to drink because in contains objectionable pollution, contamination, minerals, or infective agents.

Nonpoint Source - A contributing factor to water pollution that cannot be traced to a specific spot; like agricultural fertilizer runoff, sediment from construction.

NPL - National Priority List.

NPT - The nuclear Non-Proliferation Treaty.

NRDA (Natural Resource Damage Assessment) - Restores natural resources by returning ecosystems to full function and compensating the public for injuries to its resources. This is part of the natural resource management role of Department of Natural Resource trustees.

Nuclear Regulatory Commission (NRC) - NRC is an independent regulatory agency created out of the Atomic Energy Commission in 1975 to regulate the civilian uses of nuclear material. Specifically, the NRC is responsible for ensuring that activities associated with the operation of nuclear power plants and fuel cycle plants, and medical, industrial, and research applications, are carried out with adequate protection of the public health and safety, the environment, and national security. At full complement, the NRC has five Commissioners nominated by the President and confirmed by the Senate; the President designates one of the Commissioners as Chairman. NRC regulates all commercial Atomic Energy Act materials. Except in a few cases, NRC does not regulate DOE. NRC does not regulate NARM.

Nucleon - Common name for a constituent particle of the atomic nucleus. At present, applied to protons and neutrons, but may include any other particles found to exist in the nucleus.

Nucleus - The nucleus of an atom is the central core that comprises almost all the weight of the atom. All atomic nuclei (except H-1, which has a single proton) contain both protons and neutrons.

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