by such an explosign. aad its widespread
distribution has
lO
catisefi*a series of high-
energy discussions, and semetimes I think
the temperature achieved by these discussions has approximaged that of the cloud
itself.
1215
LATE EFFECTS OF RADIOACTIVE IODINE IN FALLOUT
|
I will make a few general remarks about
four different aspects of fallout@fom nuclear
explosions. The first concerns explosive nu-
clear devices; the second, radioactive prod-
ucts from these devices; the third, local factors influencing the distribution of these
products; and finally, the biological modulation of the fallout products.
Nuclear explosive devices are of two
types, the first being the fission reaction
that generally involves #8°U, 2°U, or plu-
tonium. The fission produges an enormous
variety of radioisotopes. There are also fu-
sion explosions, and the
Bikini ‘explosion
that we are presently discussing was a fusion explosion. Haweve¥ all thefusion explosions have to ‘be triggered, by a fissiontype explésion itt “order tg achieve the
necessary temperature:tequ
for fusion,
whichis of the order e€ 10.to 2Q0 million K.
The fusion expiosiens aite--8f -two types:
Theyare either the deuterium-tritium fusion
that produces helium plus neutrons and
energy, or the deuterium-deuterium explosion that produces either helium or tritium,
and neutrons or, in the case of tritium, a
a
| -
Ww
>
2
jo'b
wm
z
-
ow
re
~
107
oO
r—
a
iJ
a
ioe
107
——
——
1
70
233
py 239
[
f
94
8
MASS NUMBER
1
J
142
166
FicurE 1. Yield of various isotopes from nuclear re-
actions involving **U and Pu.
may decrease, and finally there may be a
relatively smooth curve. In general, how-
Pare nee
Volume 66, No. 6
June 1967
ever, fission produces an abundance of iso-
topes with mass around 136 and mass around
94. Just why fission occurs asymmetri-
cally is a matter of some interest I will not
discuss. It might be noted that most of the
radioactive isotopes of iodine have a mass
between 131 and 135 ence’ are major
fission productgg«
There is and
-_
namely, neusé
proton, plus energy. The points to remember are [1] fusion explosions are impossible
without fission so that there are always
fission products, and [2] fusion added to
fission gives an enormous increase in the
number of neutrons present, and this has an
effect on the distribution of the radioactive
decay products.
As far as the products themselves are
sionable maf
tion curve (Figure 1). There are peaks at
about 136 mass units and at about 94 mass
units for the fission of 28°U. There is a
fission of #85U, ofe -would obtain2 atorns
of palladium and an excess of 23 neutrons.
This implies. that in a. fission explosion
there is an enormous neuffon flux in the —
explosive device that irradiates the fission products, the container, and anything
concermed, there is an interesting distribu-
slightly different curve for fission of 28°Pu
and *85UJ. If the fission occurs in the pres-
ence of very high-energy neutrons the peaks