FOOD-CHAIN KINETICS OF RADIONUCLIDES
763
a, = pc N;/sq ft/R, deposited on uniform plane
N, =a given radionuclide (e.g., ®Sr or '3!1)
Estimates of a, were based on the results of radiochemical analyses, P,, and estimates of a, (theoretical values) were based on Eq. 2:
0.693F,Y
~ "FDjCR,
a =
(2)
where F, = 1.43 x 10”? fissions (23513)/kt (Ref. 23)
Y = percent fission yield (atoms/fission) of N, (4.79% ®Sr, 3.1%
1311) (Ref. 24)
T, radioactive half-life of N,; in days (50.5-day "sr, 8.04-day
131 I)
D,
3.2 x 10° dis/pe/day
C = 2.79 x 10’ sq ft/sq mile
R,= 4.5 x 104 mr/hr/kt/sq mile at 3 ft aboveground at H + 24
(Ref. 25)
The relations between initial gamma dose rates, Ry, and initial
concentrations of Sr or '!I on fallout-contaminated plants, P), were
tentatively defined by linear regression formulas. For example, where
Py) and R, are the means of P) and Ry and b,,is the coefficient of regression of Py on Ry,
*
Py = Py #£ Dyy (Ro - Ry)
(3)
The deterministic exponential models used to describe and explain
the time-specific relation between ®Sr or '*!I concentrations on plants,
P,, and of ®’Sr in bone ash, B,, or of '*I in thyroids, A,, are given (if at
t=0, P= Py, B=0, and A = 0) by Eqs. 4 to 6:
P, = Pye?
(4)
B= Pe Ge (S— +2
-
b
t
Ay Ap
—ALt
~At
Ap Ap
—dAgt
A,=Pww,f, a \Ag—Ap
(= ee
Ap Az
(5)
(6)
where t = days after fallout deposition
P, = pe *Sr/g (dry) or pe '4I1/g (dry) on plants at t > 0
Br = pe ®Sr/g of rabbit bone ash at t > 0
A,=pe '] (total) in rabbit thyroid at t > 0
Wp=8 (dry) of contaminated plant material consumed per rabbit
per day
W, = (dry) of bone ash per rabbit