‘Lhis has the solution
lI
=
a
s>”
ll
HW
~
Ne
in
A(é) = activity
thyroid
E
(uesem)
initial rate of intake of tliy-
lt
«i
if
Symbols Used
ticles (Mev)
Ko = 35 Rofl (a constant)
roidal I!) (uc‘gm, ‘dav)
radiological (physical) decay
constunt
biglucisal clecua cuitstart
time
A= Re (eet ~~ e7 Arthe))
average energy of beta par-
Thus, analyzing the thy roetd for its
D, = infinity dose (reps) to thyroid fromsingle [ intake
D, = total infinity dose (rep) to
thyroid from continual intake from {=O tot= %.
I'3! activity, A, at any time, é, one cun
figure back to the initial rate of intake,
Res.
2. Infinity P' dose. The close to
infinity from I}! intake on the first day
is
Dink [" coma
TABLE 2—Sample Calculations for Figure 1
Radiotsolope
Halflife
(hr)
whefartty*
(dpm: 20,000
Faatona)
230
49. +
54.3
3.4
374
230
226
512
—_
192
pe
[3
Te!
30
Teim
6.42
[1
2.4
Te’
37
[3
21
Te's3
l
[ls
6.7
{all short-lived;
D
Number of
aloms present
per 10,000
fiattons
26
ab
4
3
= K/(Ar + Ad)
E
F
<Alomsofiodine Average
reaching
beta
thyroid per
energy
10,000 fissions (Mev)
57.5
9. 9°
13.67
0.3¢
11.24
48.5¢
43.0:
61.6*
0.20
0.20
0.20
0.52
0.52
0.45
0.45
0.30
G
Max. rei.
energies
to thyroid
(EB x Fy
5
9
7
116
8
21.8
10.4
18.5
H
Ratio
{ShortEnergy
10 Energy
0.01
0.36
1.35
1.20
li
~4.07
* Based on Hunter and Ballou tables (1).
’ The biolugivs! fate of the isotopes of iodine is the saine. Thus, the same praportions of the tota: number of atoms of each are taken into the thyroid and then eliminated according t. the biological characteristies of the animal. The loss of an atum
of a short-hved i:ctope means a greater luss of energy to the thyroid than does the
loss of on [3 Eowever, it is to be exnected that the biological haif-life of animal
thyroids will be vocich greater than the rac.el tival half-life of even the longest shortlived radioiodine .tope (145 with Q)-nr bev-ice so that essentially all of these energies will be deir-sred to the thyccid. Fer -2s-3 where the biological decay constant,
XM.Is stemiftantiy istge comipared with t+ ridiologieal decay constant, 4+ of 15),
(0.0036 hrvly, then the values tor energies cf i +. including Te! and Te!” precursors)
given in colin
shoul! be multiplied §:- the factor Ay (A, f A? and likewise the
vaiues for the re. tive energies in colusus EF lor the short-lived isctopes should be
multiphed by th.
POT UNp me Atos.
‘AH of the iolire gtams reaching che thvicid will disintegrate there. Corrections
may be mece-sur- ording to faotrate A,
F955. of the d- - atohis taken into che Lis D reach the thvyrotd.
a of Te
emcee
tv: tinte the fds reneses the thyroul, Le, about 806% would
have disantegrar te Tes while OG: tue aut af which all disintegrates to 1'™ of which
OR
residues Tae
the toed
c
eo, Pireties
Toru
7AM 0 the Po tiins tamen ite rhe oes will disintegrate to LS! of whiel 25%
Wilh ro orehi thet
vertuye
i
Foe
eT ie tae Pho.
civ dete
cn tise
fore
ETS
Mae fhe faseeg th oye
os
1
Ce tie
bea. oar os
the Tivianad.
hese doer Pie eho
rte
Sate oe Ihe
@stimete as gk:
dd .
“hyo Wigkogiega beh tie
According to avetlabie lates
Voom rag
rh eta ts
a a
tea Phe pero tien of seriwite perce
OM + Ae. Tou values in Vable tore
Vetir baglogien] dinkt-f os of dodine ta rhe bleedd.
These alao
wave aapiaresittintes vos for sreep. cAssunare a bivlogiest bail-lite of ierline is the
Meataat shoenm el a beurcs ever aaR peril
onis, the cathes Beis Ped
peris ed 22 . hours
race te lyepe el,
oot.
Cater sueepes oat Dt ae
aheut Sac,
Hf
we
PatptayPPS Tose fuscafF ase
ioe
flow. ne tatle a: doses from individual short-lived ladine isotenes indieete ip
Mig. bsiuiests that the ratio of the total short-lived isotopes io 1@l may be underestimated for shoes livip few per cont in the early times after detonation, At later
,
tines the [22 eorituation predominates. hit also the ratio of infinity deses fran the
total short-lived tctopes to 1) fas decreased signifieantly. Thus. the method suegested here may give 2 fair approximation of the tetal infinity doses for sheep.
A3Se of the Te’? intake reaches the thyroid as T8%, Le, 50% would disintegrute
to 1 while in the gat of which 6°; will be deposited in the thyroil per footnote q.
.
F196 of the 1! taken inte the hody will be deposited in the thyroid: 256% would
-be deposited normally, but about 259% of these atoms will decaybefore deposition®.
i All of the Te! taken in will disintegrate into T'!33 while within the body of which
1975 will reach the thyroid according to footnote /,
Ir
I3b loyeal
a
:
;
}
‘
'
"eo
Fre
of: the Ts
.
iutake will
beo denosited
in
the
tieroid:
256%
would he ders ted
pean,
40
: to terr ba
leey
yb hae ty
: postion; aeeordiie, to foot: ote v.
bevore ale
Dy
K/de +s I,"eke dt
D,
K/(A, + Aa)Ar
(2)
3. Doses from short-lived isotopes.
The additional dose to the thyroid
from short-lived isotopes of iodine resulting from a stngle intake is summarized in Fig. 1. A sample of the
calculations used to construct Fig. 1 is
given in Table 2 at ieft.
In the case of grazing animals, however, the period of intake maystart at
different times after detonation and
extend for varying periods cf time.
An estimation of additional doses to
the thyroid from short-lived isotopes
of iodine under these conditions 1s summarized in Fig. 3. A sample of the
calculations ised to conusticuct Fig. 3 is
given in Table 3.
Example: Sheep Ingestion
About 3!) hours after the nuclear
aetonation at the Nevada Test Site
on Miny 19, 1953, fallout oceurredt ia
an oaien around Codie Cite, Utaty
+ aos
oF
(uuabe may oo aboub Tote (2).
ty
The infinity dose from a continuing
intake that decreases accorciing to the
radiological decayis then given by
th
C
Game ooaces
B
CNOoCorCcCS
A
(i)
CID
i!
ee ete
MET
at
Lo seme of Thos’ shacn were sarriieed
Wi Tab Ss Tee de Conrenbtre re
Were ineusured in spreenuens of their
thyisias, The highest aiensmed [>
ronrcntrations on Jule S were sont
a.
“.
aorole
Coe yo “eter.
Whit Ltygua
hare been the tetal radtotion dase to
the chvrails of these sheep from all of
Ue isetopes of rediotodinn?
birst calculate the I! close, then the
dose from short-lived isotopes. Determine the Initial rate of intake of
I'3! activity per gram, [9 from Ey. 1
A = (Re/Ra)femhet = eTOPA]
In this ense A, = O.R7ue/em when
Sie ctived Jue bo.
(Working back
February, 1956 - NUCLEONICS