detector readings (of limited use because of :nwieldiness of the detector probe), and wipe samples. These readings gave separate estimates of the contamination on an ex- tended area, the local contamination, and the loose contaminant. ‘he resultant data, when weighted and averaged, provided the basis for evaluation of decontamination procedures as well as studies of environmental influences on contamination. The results of a typical survey are presented in Figures 6.4 and 6.5. 6.2.6 Decontamination Studies. The decontamination studies were performed on many different surfaces, including ships’ steel decks, wooden flight decking, aircraft skin, and numerous common building materials. In general, the decontzmination was performed in sequence with less-effective procedures being applied first. The procedures used on shipboard were firehosing (FH), hot-liquid-jet cleaning (HLJ), hand scrubbing (HS}, surface removal (SR\, and paint stripping (PS). The basic tactical sequences evaluated were as follows: Procedure Procedure Procedure Procedure Procedure 8: A: B: C: D: FH, HLd, HS, FH HLJ, HS, FH HLJ, HS, HLJ FH, HS, FH Hid, FH Figure 6.6 illustrates the effectiveness of each procedure together with the man hours consumed. Procedure C can be performed with equipment commocly aboard Navy ships and represents a useful interim decontamination procedure. Resurfacing of a wooden deck with the Tennant machine subsequent to nondestructive decontamina ion resulted in a net decontamination effectiveness of 70 percent in gamma radiation and 90 percent in beta radiation. Application of a water emulsion paint (Formula 980) and its removal subsequent to contamination resulted in a decontamination e. ectiveness of approximately 80 percent. The basic technique was sound, but further development was needed to make the paint more-easily applied, more durable, and more-easily removable. The aircraft exposed aboard the ships were subjected to decontaminzntion procedures and regular material-damage inspections. The results of the decontamination procedures were classified into three groups depending on the previous history: Condition A, only slight washing by rain; Condition B, washing by heavy rainstorms; and Coadition C, subjected to washdown. Figure 6.7 demonstrates the effort required to reduce the contamination to a given fractional level. The procedures consisted of repeated firehosing, hot-liquid-jet washing, and eventually scrubbing with detergent and Gunk solutions. The aircraft received in Condition C were immediately firehosed and then scrubbed with detergent. The results of the decontamination procedures applied to building-material panels after Shot 2 are summarized in Figure 6.8. The panela were exposed in normal) orienta~ tions: pavement horizontal, walls vertical, and roofing on a slant. The variation in the gamma radiation before decontamination was principally due to orientation, with the vertical panels approximately three times as active as the horizontal ones. The same effect was observed after Shots 4 and 6, but by a factor of lesa than two. Wind impacting the fallout material on the surfaces possibly was che explanation. Surface-removal studies indicated that the activity penetrated to a maximum depth of 200 microns in painted wood. Studies performed at the Army Chemical Center indicated that the active material was 84