CHAPTER 2
EXPERIMENT DESIGN
2el
DESIGN CRITSRIA
The collectors were designed to collect liquid and solid fallout
samples at preset, successive time intervals which could be adjusted
to between 1 min and 30 min. The samples were at least large enough
to be analyzed by standard counting techniques.
Base surge estimations from work done by the Naval Ordnance
Laboratory Task 152 indicated taat the maximum radius of the surge from
the CASTLE devices could be from 15,000 to 34,000 ft, depending upon
the yleld of the devices. The phenomena should he complete within 10
or 15 min after detoration. The base surge was primarily expected from
the surface water shots; however, Shot 1, detonated on a reef, was instrumented for dbase surge samples because it was thought that the reef
was so narrow that the shot would be, in effect, a water shot. Since
high overpressures are encountered in the base surge region, the fall=out cellectors in the region were ruggedly built. These collectors
were set for I-min intervals. &xperience at IVY_3/ indicated that the
heaviest fallout on the atoll cccurred within the first 30 min after
the detonation and thet fallout continued to occu more than 6 hr after
the detonation, which was the maximum sampling time of the IVY collector.
Thus, two collectors were generally placed at each stations (1)
one sampling at l-or-5-min intervals for a total time of 24 min
or 2
hr respectively, to document the base surge or early fallout; and (2)
the other sampling at 30-nin intervals for a total time of 12 hr.
Basically, the same type of instruments were used to sample falle
out on the surface land and surfece water shotSe
2.2
THE INTERMITTENT FALLOUT COLLECTCR
The intermittent fallout collector (IFC) consisted of a circular
dise (or "spider") divided intc 24 sectors, a driving and timing mech-
anism
and a housing (Figs. 2.1-2.3).
ach sector contained a triangu~-
lar tray 3 3/7 ine x 10 in., anu 3/4 in. deep.
One tray at a time was
exposed to fallout throwh an opening of equal size in the top covere
The wide end of each tray held four glass counting cups (1 in. in
17