Table 3.

Element-specific ecological half-times parameters of the contribution to the external dose rate 1 m above ground from fallout in terms of a double exponential decay function (Eq. 9) for the elements represented in the nuclide vectors in Table 2. N/A = Not applicable.

Nuclide	cshort,i	Teco,i,short (y)	Teco,i,long (y)
110mAg	0.63	0.6	22.7
140Ba	0.63	0.6	22.7
82Br	0.63	0.6	22.7
144Ce	0.63	0.6	22.7
134Cs	0	0.6	3.2 or 6.7 or 15
136Cs	0	0.6	3.2 or 6.7 or 15
137Cs + 137mBa	0	0.6	3.2 or 6.7 or 15
131I	1	0.125*	22.7
132I	1	0.125	22.7
133I	1	0.125	22.7
135I	1	0.125	22.7
140La*	0.63	0.6	22.7
99Mo	0.63	0.6	22.7
95Nb*	0.63	0.6	22.7
97Nb	0.63	0.6	22.7
144Pr*	0.63	0.6	22.7
103Ru	0.63	0.6	22.7
106Ru + 106Rh	0.63	0.6	22.7
125Sb	0.63	0.6	22.7
127Sb	0.63	0.6	22.7
89Sr**	N/A	N/A	N/A
90Sr + 90Y**	N/A	N/A	N/A
99mTc	0.63	0.6	22.7
131mTe + 129mTe + 129Te	0.63	0.6	22.7
132Te	0.63	0.6	22.7
132Te + 132I	0.63	0.6	22.7
95Zr	0.63	0.6	22.7

*Based on the initial slope of ambient equivalent dose rate data from Jönsson et al.⁷.

**For the pure beta-emitters ⁸⁹Sr and ⁹⁰Sr/⁹⁰Y, the bremsstrahlung generates an external dose contribution that will be ecologically damped more rapidly than for gamma emitters. According to Kumar Sahoo et al.⁴⁴ radiostrontium migrates at a rate of ~1 cm y⁻¹ which, in combination with data from the ICRP¹⁴ suggests that the bremsstrahlung component decreases rapidly (T_eco,Sr,short < 1 y).