GAMMA-RAY SCANNING TECHNIQUES FOR FAST BREEDER REACTOR SAFETY STUDIES

A radiation scanning device was constructed to observe meltdown of fast breeder reactor fuel elements in the TREAT reactor by means of self gamma emission. Although the original desired specification was to view natural uranium pins with a space resolution of 0.1 in. and a time resolution of 1 millisecond, the system was designed to give the above space resolution, but the time resolution would be 5 milliseconds or longer depending on the signal intensity. The system failed to give satisfactory pictures because of low signal strength which gave poor contrast against high-strength background from the container required for safety reasons. Measurements indicated that a Mark III system could be constructed to view enriched pins in the standard container with a space resolution of 0.15 in. horizontally and 0.75 in. vertically with a time resolution of 5 milliseconds. (auth