detector readings (of limited use because of unwieldiness of the detector probe), and
wipe samples. These readings gave separate estimates of the contamination on an extended area, the local contamination, and the Ilcose contaminant.
‘Che resuitant data,
when weighted and averaged, provided the basis for evaluation of decontamination procedures as well as studies of environmental influences on contamination.
of a typical survey are presented in Figures 6.4 and 6.5.
The results
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 decontamination 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, HLJ, HS, FH
Hid, HS, FH
HLJ, HS, HLJ
FH, HS, FH
HLJ, FH
Figure 6.6 illustrates the effectiveness of each procedure together with the man hours
consumed.
Procedure C can be performed with equipment commonly 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 subsequentto
contamination resulted in a decontamination ei.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 decontamination 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 Condition 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 panels were exposed in normal orientations: pavement horizontal, walls vertical, and roofing on a slant. The variation in the
gamma radiation before decontamination was principally due to orientation, with the ver-
tical 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 less than two. Wind impacting the
fallout material on the surfaces possibly was the 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
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