plus the polyvinylacetate surface covering is very ncarly equal to the thickness of the
inert layer of the skin.
The apparent total dose (Figures 3.3 and 3.4) decrease3 smoothly as# the absorber
thickness is incrvased end finally reaches a constant value. If thia constant value is
tak2n to be the gamma dose to which the stack waa exposed, the apparent beta dose can
be calculated by subtracting this amount from the apparent total dose. A curve that ropresents the absorption characteristics of the beta contamination alone can then be drawn.
This was done in Figures 3.3 and 3.4.
The results of nig method of anajysts are summarized for all of the film stacks in
Tables 3.3 and 3.4 under columna headed ‘‘Hot Spot B/y” and “Area B/y.” Ln general,
these ratios agree rather well, e..:pecially for the average dose rates measured by the
individual filme and the T1B.
ABSORPTION BY STANDARD GLOVES
An attempt was mate ts:
reduce the contact hazard 72
dion of cach of the thirteen:
A preliminary cv@luation
cluste inv extent to which various types of gloves would
wroicn tee s:urer would be subjected. A complete descrip© 2r¢.11 groves {3 riven in Appendix B.
was obtained by interposing the glove swatches hetween film
and the Sr®-y™ standard source. The column headed “Absorption Sr”-y”” {n Table
3.5 shows the percentage of the incident radiation which was absorbed by the glove ia
question. fach percentige is the average from at least eight exposures ranging from
0.5 to 60 rep. The average deviation for each percentege value was less than 5 percent.
A Berieo of exposures was made tn which films “ere exposed to a contaminated sur-
face, both with and without the interposition uf a glove swatch. The area chosen was
the leading edge of the wing of a B-57B that had penetrated the cloud from a megaton-
range burst.
The fourth column of Table 3.5, headed ‘‘ Reduction of Average Dose Rate
To Hand,” shows the percentnge by which the dose reaching the film from the aircraft
is reduced by the glove. The film densities were read through the large aperture on the
densitometer.
This cu1uimn, then, represents the percentage by which the dose to the
hand as a whole would be reduced. Hepeat measurements for some of the gloves were
made on subsequent shots. These are indicated on the table.
It will be noted that the percentage absorption on the aircraft exposures {6 greater
than that on the Sr*-y®™ calibration source. This is an indication that the average energy
of the contamination is lese than that of the radiation f om Sr?-¥"?,
Since the primary contact hazard is caused by the email “hot spots” of intense radia-
tion, it is instructive to compare the maximum dose rates observed on a surface with
and without the interposition of 4 glove swatch. The percentage by which the max!mum
dose rate is reduced is shown in the last column of Table 3.5. It is observed that al!
glover reduce the maximum at least 50 percent. This is due in part to actual absorption
by the glove material and in part to the scattering caused by the increased Itnear separation between the contamination and the film. In addition, no residual contamination was
observed on the hands of personnel who wore leather, rubber, or vinyl-coated gloves
Figure 3.5 shows 4 number of radioautographs made with and without the interposition
of several different glove swatches.
From the standpoint of case of movement and comfort to the wearer, as well as from
the standpoint of the protection provided, the vinyl coated cotton glove (N». 13) ora
combination <4 jersey liner and leather flying glove was found to be more satisfactory.
Any of the gh es not containing leather could be decontaminated by laundering. The
vin |-coated 4..ve had the advantage that the wearer could remove most of the contami-
SECRET
meek Gari rreney HS Reenter aa
3.6