SLIDE 12
Iodine activity on the surface.
Based on archival soil measurements the
fodine isotope activity per unit area of soil at the cessation of fallout at
Rongelap was tabulareg.
the same amount as
It was assumed that todine {sotopes were enriched in
I, as indicated to us by archival soil results.
The
total radioiodine soil activity per unit area, based on archival soils from
Rongelap, exceeded the measured total activity per unit area by a factor of
ten!
The total activity per unit area was based on four soil samples taken
and measured for gross beta activity on March 8, 1954 (0C68). Conversion of
the fodine surface activity (derived from archival soils) to exposure rate one
meter above a plane source yields an estimated exposure rate 12 times greater
than what was measured.
Because of this disparity, the ggsumption could not
be made that iodine isotopes reflected the behavior of
I in archival soils.
The level of 1297 in archival soil may be real, an artifact of the
neutron activation technique, or the residue from other weapons tests
occurring near the ,gime of soil collection. Comparison of Bikini Ash 1297 to
the hypothetical
I leads one to believe that some enrichment of occurred
but not to the extent indicated by our extrapolation of archival soil
measurements.
ACTIVITY PER UNIT AREA AT RONGELAP
0.6 DAYS POST DETONATION
Nuclide
129
Bq m™?
Exposure Rate One Meter Above Plane of Activity
Archival Soils
Measured Total Exposure Rate
5.2 10°
-
=
ty
~ 7.0109
193
7.4x10°°
, 24
9.3x10"°
7.0
132]
194]
135)
0.14 °
2.2«109'°
2.5
7.4x10°
0.098
17