eum 0.25 to 6.0 inches, chambers, Fach detector consisted of 3 packagei ionization The pipes with detectors and an unshielded detector were enclosed in a thin aluminum dome so that the geometry of radiation sources would be identical. A field test was to be made of a prototype detector-recoriding system as a part of the laboratory's long range development. Miscellaneous gamna radiation measurements were to be made by means of unshielded recording radiation detectors located on the kingpost sampling platform, in the tridge, in the fireroom, in the recorder room, and in Number 2 hold. RESULTS The raliation levels encountered by the two YAGs were too low to supply data adequate for the satisfaction of all objectives. The instrumentation performed satisfactorily, however many radiiation detectors were operating near their lower limits of sensitivity. Where feasible, for subsequent particination, more sensitive detectors were installed in place of the highest range detectors, Relative Gamma Paiiation Fielis Contributel by Various Raiiation Sources Fig. 2.71-1 shows a rather rouch estimate of the air contribution to the radiation field on the deck of YAG 40. It should serve to in- dicate the duration of fallout. The accuracy of the preliminary analysis of the relative ccontributions by the various radiation sources does not warrant a presen- tation of quantitative results at this time, Interaction of Gamma Radiation with Steel Gamna fields inside steel cyliniers of various thicknesses Lor eo'on¢ rene RC _