recommended earlier (ICRP 2, 1959).
The effects of variations in 7? or
exposure period are much smaller, for the range of parameter values of
interest, being less than a factor of 2.
Table 5.
Ratio of *39Pu Burden in Bone. f° Rate Which
239py Reaches Blood (yp/r,)
Fraction From
Blood to Bone
(fa pw
Biological Half-Time for Bone (re), Years
70
100
130
160
200
50-Year Exposure
0.45
0.5
0.6
0.7
0.8
6477°9)
7197
8636
10076
11515
|
6940
7712
9254
10796
12339
7209
8010
9612
11214
12816
7384
7540
8204
9845
11486
13127
8378
10054
11729
13405
9918
11020
13224
15428
17632
10209
11343
13612
15881
18150
70-Year Exposure
0.45
0.5
0.6
0.7
0.8
(a)
8294
9215
11058
12901
14744
9110
10122
12146
14170
16195
9596
10662
12794
14927
17059
Units of ratio are day.
CONCLUSIONS
The results of this analysis are not surprising.
Soil concentration is
the most significant source term and is subject to a great deal of
variation.
The parameter for relating the soil concentration to the
concentration in air is also very significant and also subject to wide
variations.
It is, perhaps, surprising to see the variation in estimated
dose rates that could result from uncertainties in the size and chemical/
physical properties of plutonium-bearing particles.
However, dose
variations due to particle size are much less than those due to variations in soil concentration and mass loading factor, and it is generally
assumed that the plutonium-bearing particles at NTS are of such a chemical
and physical nature that they are always in the year translocation
class.
534