Terr
z Short (total),
By GORDON M. DUNNING
Division of Biology and Medicine
U.S. Atomic Energy Commission
Washington, D.C.
o
r
G.t
TTT rrttTy
Ratio of Doses Short, 13!
Single Intake
o
—
0.01
boo
tit
pipe
1 booriiil
10
100
1.0:
” Time trom Detonation to Intake(hr)
Foe
wil
L000.
€
Boe
oe
ee
wad
FIG. 1. Approximate ratio of infinity dose to thyroid from short-lived radioiodine isotopes and |'*! for case of single intake. See Table 2 for sample
calculation of these curves
Two Waysto Estimate
Ore
of Twine foto in tadeut materia
betnher ut
,
Tho
Sala tleeles
pial situation,
tlawe ver, it is offen essential tu make
such estiniates, ever though cimittedly
based on amited deta.
There is disagiecment as to the
principal mode of entry into the body
of the radioactive I contained in fallout, ie., inhalation or ingestion. For
low-yield detonations, such as in
Nevada, relatively higher concentrations of fallout materia! are found in the
air for only a matter of a few hours
withoess tially all of caleulited intake
by inhulation completed within 24
hours for nearby communities.
When
the
detonations
occur
S
thea Vueifie proving ground the activitt in the air may persist for someawe
we hat longer times in the U.S.
Thus,
rac relatively early. short exposures
dose from Fe"! and its precursors and
the camownd of
ede vi rie
at
intake
¢ VOW hteGn
:
oe ye
wal Be mero a Slot Tak tes ipges
tion.
Wal.
ose from
e in Fallout
Towever. to one sameness feor
mal ingestion for. continuing periosl,
it would appear diis is by far the
Gotiinggl facki. Ui ts eapectally:
true for raging aviids. ai fact,
field experigiont: eae tho Neiada
test site showed there was little {in
the thyroid of rubbits, who were restrained so that they could not ingest
any material but could continue to
inhale during and after fallout.
The problem of dosage calculations
is complicated by the presence, at
early times after detonation, of shortlived [isatepes in addition to I! and
a telluriin precursors fur several.
The general upproach given below
for these problems is to caleulate the
then add to this the contribution from
the short-lived isotopes of T and their
presursars.
too
rebtiye 2 lua
hades
the
aly
lates
ey ry ee yea ne PPh Det pet
DEE Pa
ae
pe
Their proterves nee wiven in Table i.
Calculates> Dose
The veut co tppctehetian ar ie optaee
to tre phoresis Aifficnlt heeeuse of
Caittainties of the percentage
ot tatane into body that reaches
the thyroid,
.
b. The tellurium precursors that result in the absolute activity of
the 15! in the environment remaining roughly constant for
about a day followed by a period
of increasing decay rate until the
per, -G9S Le Gumgel pays steth
eant role and the decay rate
then becomes that of £151,
a.
February, 1956 - NUCLEONICS
38
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wer
7
.
de.
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ih
mr
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+o)
CALCULATING Pahiatic:
fallout presents uri... crableins,
of thes2 is haw +
TOs areca intabe
be
wh
@
Thyroid