SHIELDING CALCULATIONS FOR COFFINS FOR VERTICAL HOLE PLOTS

摘要

Calculations on the VG-9 carrier indicate a necessary Fb thickness of 12 for the down end and a 10n Jacket thickness over the lower plus (graphite) The high induced activity here is caused by the 1/4 steel plate on the bottom of the graphite in a flux of about 1013 and by the 1/2a steel rod which runs the length of the lower plug. The 12 end shield should reduce the radiation to about 3 ar/hr at one foot, immediately after shutdown and the 10 jacket should give about 3 mr/hr at one foot Since the activity is due principally to Mn in the steel, and the Mn has a half life of 2.6 hours, the shielding requirement would not be reduced significantly by any reasonable waiting period.