Heat Stress Control in the Three Mile Island Unit 2 Defueling and Decontamination Activities

The Three Mile Island Unit 2 (TMI-2) defueling and decontamination activities required workers to wear several layers of protective clothing when they worked in the highly contaminated environment of the TMI-2 reactor building (RB). It was recognized that the insulating properties of the protective clothing would impose heat stress on the workers. A specific program for the control of worker exposure to heat stress was developed, including medical testing of workers, training and education, work time limits, and the extensive use of “ice vests” as a personal body-cooling device. The logistical and operational aspects of each phase of the program are also addressed. Finally, the use of engineering controls to combat heat stress in the RB and to reduce the reliance on personal protective devices is described.