TABLE 3.14 - Averages of Cumulative Fer Cent of
Radioactive Particles Under Stated
Size Ranges
Shot
Under 52
Under 10 p
1
20
43
74
31
68
3
8.8
Under20n |
The Shot 1 particles were also found to have 43 per cent of the parti-
cles under 10 p, which was about 14 times as many particles in the
same size range as those collected from Shot 3.
However, the percen~
cent) in the samples collected from both shotse
Apparently, Shot 1
tage of particles under 20 p was approximately the same (about 70 per
produced 4 larger percentage of particles under 5 pn and 10 p than did
Shot 3.
The size range under 5 p is the range of particles which is
most likely to be deposited at som point in the respiratory system,2/
except for particles below 0.1 p or 0.2 mp, which tend to be exhaled.23/
These results also indicete that Shot 1 particles would be harder to
decontaminate than particles from Shot 3. The Shot 1 percentages are
higher than those that have been found at previous tests and may be
due to improvements in analytical technique, but it is felt that the
difference in the results is mre likely to be due to the differences
of the particle characteristics themselves.
3e9eL
Activity in Size-Fractionated Particles.
The percentage of total activity of each fraction of a size
fractionated sample, which was collected from How Island after Shot l,
was determined by Project 2.6b. 12/ It should be pointed out that these
particles were primarily fractionated for radiochemical analysis.
Particles below 44 p were separated by a roller analyzer so somes agglomerates were probably broken up. The particles above 44 p were
fractionated by sieves so fewer agglomrates were probably broken up.
Table 3.15 presents data which is a by product of the radiochemical
analysis procedurese
The per cent of total activity in the two
smallest fractions is about 23.4 per cent of the activity found in
the entire sample and second only to the activity in the largest
fraction (32.9 per cent).
The activity in these two smlilest frac-
tions would constitute the principal pulmonary hazard in this fallout.
However, the internal hazard caused by these particles is almost
always overshadowed by the external radiation hazard existing in the
same region and so the internal respiratory hazard may be relatively
unimportant.
It should also be poimed out that these results
89