Abstract
Krypton-85 has recently replaced radium bromide as the residual ionization source in cold cathode gas discharge tubes manufactured by the Western Electric Company. This change was carried out to reduce radiation exposure to personnel during manufacture and use of the tubes. The personnel protection program, which had been in effect for radium bromide, was modified to conform to the special properties of krypton-85. This modified program consists of area monitoring, personnel monitoring, and occupational medical examinations. Some occupational exposure data are given and are compared to similar data for radium bromide. The use of krypton-85 has reduced the radiation exposure of the employees below the previously low levels encountered when radium bromide was used.