Working level (WL) is a historical unit of concentration of
radioactive
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consi ...
decay products of
radon, applied to
uranium mining environment.
One working level refers to the concentration of short-lived decay products of radon in
equilibrium with 3,700
Bq/m (100
pCi/L) in air. These decay products would emit 1.3 × 10
MeV in complete decay.
The
Nuclear Regulatory Commission uses this definition.
Working level month (WLM) is a closely related quantity, referring to exposure to one working level for 170 hours per month. This comes from assuming a 40-hour
work week.
In 2002, the NRC regulations limited exposure in mines to 0.3 WL, which was comparable with the standards of
International Commission on Radiological Protection at the time.
References
Units of radiation dose
Radon
Radiation protection
Mine safety
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