i-hr exposure
6-min exposure
Distance,
em
Dose,
mr
58,1
65.3
75.5
92.9
10,000
8,000
6,000
4,000
131
185
207
240
200
100
80
60
2,000
1,000
800
294
40
131
185
207
Distance,
cm
Dose,
mr
Circles were drawn with radii equal to the distances given above, and slotted pegs were
set into holes drilled on the circumference of the circle. The distance between adjacent pegs
was such that the slots gripped the edges of a film badge when inserted between them with the
long axis vertical. The pegs were placed on a spiral in order to minimize scatter.
The calibration curve was extended by placing film badges at the proper station and exposing them for 10 hr instead of 1 hr,.as noted in the table above.
B.3
STANDARD FILM BADGES
“Standards” were film badges exposed to a known amountof radiation and then developed
with the unknown film. A comparison with the calibration curve detected variations in the development procedure.
Standards used were exposed as a group to 500 mrprior to the first shot and then stored
with unissued film. A standard was included with each batch of film developed.
B.4
FILM-BADGE PROCESSING
All film-badge processing laboratories that were operated at the Pacific Proving Grounds
were air conditioned to reduce emulsion breakdown caused by excessive heat and/or moisture.
Film badges were stored in a refrigerator at a temperature of 40°F. A drying agent in
open pans was placedinside to reduce the air humidity.
Film-badge standards and controls were allowed to come to room temperature before
development.
Development was usually done at night after all film badges of recovery parties were collected. Exposures so obtained were filed nightly so that accumulated doses were up to date for
the operation for the following morning.
B.5 PROCEDURE
Equipment
Film badges were processed in three stainless-steel tanks containing 5 gal each of developing solution, stop solution, and fixer. The temperature of the solutions was maintained
at 68°F by being immersed in a water bath that was thermostatically controlled.
After development, film badges were washed in running water of the same temperature.
Drying was accomplished by passing heated dry air over the badges.
All development was done under safelights of the Wratten 6B type.
B.5.2
Film-badge Development
Film badges were carried into the darkroom in wooden carrying boxes. There the lightproof covering was removed, and the film components were loaded into LASL type racks, the
65
ae
B.5.1