Page 700 - Radiation Safety
P. 700

SOURCES OF RADIATION EXPOSURE







                                                    WORKING LEVEL (WL) – unit for radon daughters

                                                                               concentrations in air




           • 1WL = combined short-lived radon daughters in 1L of air that produce potential α

                                                    5
              energies of 1.3 x 10 MeV. A smaller unit, mWL is also used.



           • Working Level Month (WLM) = unit of exposure to radon or thoron daughters for 170h.




           • Annual limits for workers: 4 WLM for radon & 12 WLM for thoron daughters
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