Office of Research

VII. Contamination Limits and Control

 A. A Restricted area is any area to which access is controlled for the purposes of protection of individuals from exposure to radiation and radioactive materials.  Before removing any piece of equipment from a restricted area where unsealed source material is used, a contamination survey will be performed on the equipment.  Unrestricted area limits will be met for unconditional release of items or equipment from a Restricted Area, such as, a laboratory which is designated as a Radioactive Materials Area.

1. Unrestricted Area Limits


Type of Contamination: Beta / Gamma Alpha

Removable      <200 dpm / 100cm2    <20 dpm / 100cm2

 

Fixed        < 100 cpm above background  N/A

or    <0.5 mR / hr

 

2. This is a direct reading that should be taken with a G.M. instrument calibrated in cpm or in mR/hr equipped with a thin window, pancake or end window probe.  Direct readings of >100 cpm above bkg. or >.05 mR/hr above area background when measured at near contact with the source (a distance of no more than 1/2") indicate a contaminated article or area.

3. Background in the area where the measurement is made will be no more than 300 cpm.  Some instruments acceptable for this purpose are: Ludlum model #3, Eberline E-120/E-530, RM-14, 16, & 19