radioactive debris associate? What
out and mixing of fallout deposited
Owing to the incompleteness
CROSSROADS, essentially nothing was
is the rate and extent of <ettling
on the water surface?
of the data taken at Shot Baker,
known prior to CASTLE concerning
the mechanism of formation of wet contamination from this type of burst,
The relative contributions of base surge and fallout were uncertain;
the roles of condensation, evaporation and mixing with sea water in the
production of either base surge or fallout were unknown.
Particle size
and individual particle studies undertaken at JANGLE and IVY have ylelded
considerable information on the mechanism of formaticn, dispersion and
reactions of dry contaminants from these operations .2292%442/
1.1.2
Assessment of Radiological Situations
Extensive laboratory contamination-decontamination programs have
been undertaken to solve presumed field radiological problems but in
many cases lack of fullescale test data has made it impossible to define
them cleacly. For exarple, before CASTLE it had not been determined
whether an interns] contamination hazard would be produced on ships by
radioactive aerosols from an underwater detonation, because the nature
of such aerosols was unknown; the relative contribution of gamma radiation from fallout in the water with that on contaminated ships could
not be calculated because the rate of settling or mixing of the contaminant in the water was unknown.
Insoluble perticies will cettle depend-
ing on size and density while dissolved (ionic) contaminants will mix;
colloidal material, if present, will mix and settle slowly. The assess-
ment of such radiological situations and the development of countermensures require a knowledge of many physical and chemical properties of tho
contaminant.
Linited data exist with regard to the contaminants which may be
produced by surface and underground detonations because of the atypical
nature of the soils at IVY and JANGLE. No direct information has been
obtained on the nature of contaminants from underwater detonations. For
this reason, there is special interest in surface water shots which
should produce a contaminant most similar in nature to that from an
underwater detonation.
1.1.3
Specifications
of
Simulants for Radio
ca
it,
t
If meaningful laboratory contamination-decontamination results
are to be obtained, it is essential that the artificial contaminants
used must simulate real ones in chemical and radiochemical composition
and in important chemical and physical characteristics. In the past,
the radiochemical composition of artificial contaminants 14/has been
based upon yields of various radicelements from slow fission of 0235,
It ia important to know the extent of difference in fission yields for
nuclear processes other than slow fission and whether induced activities
contribute appreciably to the contamination. Finally, it is necessary
to evaluate the relative contribution ¢ esch radiocelement to contamination fielde on the tasis of its yield and the number and energy of the
gamma rays emitted by the various radionuclides of that element,
16