Neutron Radiation - doe-hdbk-1188-20060137

DOE-HDBK-1188-2006

126. NEUTRON RADIATION. The emission of neutrons from atomic nuclei. Neutrons are uncharged

subatomic particles of nearly the same mass as protons. Interaction with atomic nuclei in matter results

indirectly in ionization and thus an absorbed dose to biological material. Neutron bombardment of

heavy nuclei (e.g., uranium, plutonium) can result in fission. Highly penetrating, neutrons can be

stopped by thick masses of concrete, water or paraffin. [Derived from IAEA]

127. NONATTAINMENT AREA. An area that the U.S. Environmental Protection Agency has

designated as not meeting (i.e., not being in attainment of) one or more of the National Ambient Air

Quality Standards (NAAQS) for sulfur dioxide, nitrogen dioxide, carbon monoxide, ozone, lead, and

particulate matter. An area may be in attainment for some pollutants, but not for others. [See

attainment area, National Ambient Air Quality Standards (NAAQS), and particulate matter.]

[Derived from EPA Terms]

128. NONINVOLVED WORKER. A worker who would be on the site of an action but would not

participate in the action. (See involved worker.) [Recommendations Book]

129. NUCLEAR FACILITY. A facility that is subject to requirements intended to control potential

nuclear hazards. Defined in DOE directives as any nuclear reactor or any other facility whose

operations involve radioactive materials in such form and quantity that a significant nuclear hazard

potentially exists to the employees or the general public. [Derived from DOE 6430.1A, DOE

5480.30]

130. OVERPACK. In general, any container into which another container (usually a waste container) is

placed. An overpack might be used to provide shielding and structural support (for example, during

transportation), to provide additional physical containment for the contents of the inner container, or to

enclose a damaged container.

Provide a document-specific definition if appropriate.

131. PARTICULATE MATTER (PM), PM10, PM2.5. Any finely divided solid or liquid material, other

than uncombined (i.e., pure) water. A subscript denotes the upper limit of the diameter of particles

included. Thus, PM10 includes only those particles equal to or less than 10 micrometers (0.0004 inch)

in diameter; PM2.5 includes only those particles equal to or less than 2.5 micrometers (0.0001 inch) in

diameter.

the true diameter, but is the diameter of a spherical particle of unit density (i.e., 1 gram/cubic

centimeter) which behaves the same way as the particle under consideration. Thus, for

example, a spherical particle 10 micrometers in diameter with greater than unit density would

not be included as PM-10 because it would fall at the same rate as a particle with unit density

and diameter greater than 10 micrometers.

[Derived from EPA Terms, 40 CFR 50, 40 CFR 61.171]

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