WORLDWIDE EFFECTS OF ATOMIC WEAPONS
SAMPLING AND RESEARCH PROGRAM
by 7 in. One of these involves first drawing & random subareas for sam-
it, indeed, must remove particles however small. This latter point is
susceptible to direct test, however, by use of several barrier series and
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pling, and then within these subareas drawing m samples of soil, where
km == N,the total sample number, each of which is equal to 1/Nth ofthe
volume of soil required. The most advantageous sampling procedure will
depend on the variability of the Sr°° level in the soil within the area and
on the relative cost of going to the & subareas as compared with the cost
of taking each sample of 1/Nth of the required volumeof soil.
3. The actual analysis of the data, once collected, is so straightforward
(unless analyses other than the sample determination of the Sr°° level
and inert strontium level are undertaken, e.g., analyses of the soil composition andits effect upon the availability to plant life) that there is no
need to mention it. The primary problem is the collection problem andit
is here, on matters of detail that cannot be foreseen now, that the help
of a statistician is most needed.
Similar consideration will enter into the design of the collection pro-
gram for the other types of materials, e.g., animal bone, etc.
ANALYSIS FOR STRONTIUM 90
Sampling
The general principles of sample treatment and measurementare fairly
obvious. One must, in the first instance, collect a fair sample of the realm
being investigated. We must take a fair portion, bearing in mind the vast
mixing problem, and then collect from this portion all the radioactive
fission products present. From remarks made previously it is clear that the
collection of all the radioactive fission products present may not be a
simple task, particularly in the case of the atmosphere, for we have the
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observance of the distribution of the radioactivity. That is, if the barriers
are completely effective, the first in the series will absorb all the radioactivity. If it is true that diffusion barriers can be utilized to make a
complete radiochemical assay on air, one might well develop a technique
of producing otherfilters less security sensitive, but which will perform
as well for the problem of removalof the colloidal aerosol fission-product
matter from the atmosphere. This could be done by using bomb debris
as test material, i.e., by purposely selecting fallout material as test mate-
rial, or possibly by synthesizing similar material in the laboratory and
conducting tests on various filters. This work could be done in the Carbide
and Carbon Corporation laboratories in the diffusion plant at Oak Ridge.
Professor John Turkevich of Princeton University has observed that the
particles produced by an electric arc between aluminum electrodes in air
have particle sizes in the range of 0.01 » and smaller. It is conceivable,
therefore, that the use of radioactive material for the electrodes would
allow one to synthesize an aerosol similar to that produced by the atomic
bombs. Then this might be used in developing adequatefilters.
In sampling the hydrosphere one must remember the propensity of the
radioactive material to pass throughfilters. It seems, therefore, that evap-
oration is necessary. The evaporation of considerable volumes of wateris
an unsavory task, but in the absence of information as to how to be certain
of the removal of the fine colloid, no alternative seems to be available.
Following evaporation, the salts left can be treated for the dissolution of
such inert materials as silicon dioxide, aluminum oxide, etc., so that the
radioactivity will be in true solution. The procedure for this is well known
to be the treatment with about 50 per cent hydrofluoric acid solution in
platinum vessels. This procedure will suffice. It may be unnecessarily
possibility that a considerable portion of the radioactive particles invalved
are of a very small size—i.e., less than 0.1 » in diameter and possibly of
drastic, however, as only direct test can show. The carrier elements, such
isolate. The method of electrostatic precipitation 1s presently being exploited by the Stanford Research Institute and by the New York Operations Office of the AEC. The results are encouraging.
Additionally, we recommend that a study be made of possibilities of
the diffusion barrier, since it is clear from its physical characteristics that
misleadingly tow assays could be obtained. It is difficult to overemphasize
the importance of guarding against the lost part of the radioactivity in
ultra-fine colloidal form.
Lithosphere sampling is quite difficult in that the treatment of any
the order of 0.01 yw. Particles of this dimension are extremely difficult to
as strontium, should then be added and an ordinary radiochemical analysis