conteining a detergent and a complexing agent.
followed by scrubbing and then flushing.
This is immediately
The additional dose
received by workers during this scrubbing operation, because of the
higher field present during the operation, may well be compensated
for by the fact that only two operations are required instead of
three (scrub, flush, instead of hose, scrub, flush), As indicated
elsewhere in this report, it is felt that consideration should also
be given to the use of detergent systems without water.
The washdown countermeasure operation conducted on the YACG 39
panels was more effective in minimizing final contamination levels
than post-attack decontamination operations on unprotected panels.
However the practicability of exterior water sprays on fixed
structures with surface irregularities cannot be ascertained at this
time.
Residual perce:.tages obtained from beta activity measurements
deviated significantly from percentages obtained from gamma measurements, This deviation generally indicated lower residuals, sometimes
by as mech as a factor of two on very rough and porous surfaces.
(See Tables B.2 and B.3)
It is believed that the decontamination
operations which were conducted tended to drive the contaminant into
the surface, which had the effect of masking the beta activity. In
view of this condition, the results based on the beta activity are
considered to be grossly misleading and are inciuded in this report
for informational purposes only.
While the tabulated results show some evidence of "saturation
effects" - which theory postulates that the higher the initial
contaminant activity, the lower the residual percentage that can be
obtained ~ the levels recorded were not high enough to justify a firm
conclusion,
If the saturation effec’ theory is valid, it would mean
that under contaminated conditions of real military interest
(thousands of roentgens per hour at H + 1 hour) lower residual
percentages than were obtained in this operation would be achieved
by use of the same decontamination methods.
5.2
PHYSICAL AND CHEMICAL INVESTIGATIONS OF SURFACES
In continuation of investigations initiated at the test site,
several test surfaces were radioautographed and examined
microscopically at the Army Chemical Center to determine residual
particle size and contamination distribution, In every case
investigated, there appeared to be a smear of contamination with a
more or less uniform distribution of "hot spots",
5.2)
(See Fig. 5.1 and
However, these investigations failed to detect any particulates
associated with this activity.
By slicing off surface layers of
bare wood and the alkyd resin coating with a microtome, it was
determined that the contaminant had penetrated into the surface,
In
both cases, removal of 200 microns effected complete decontamination.
Figures 5.3 and 5. show the radioautographs of the alkyd resin
coating initially, after 100 microns had been sliced off, and after
a total of 200 microns had been removed.
Figure 5.5 illustrates
the effect of slicing off successive surface layers in contaminant
removal.
2
CONFIDENTIAL— RESTRICTED DATA