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The effect of a moderator volume fraction on the transmutation rate and absolute quantity of
iodine transmuted is presented in Table 7.
Table 7. The effect of moderator volume fraction
on 129 I transmutation efficiency (radial blanket/axial blanket)
Moderator volume fraction (ZrH 2 )
%
0 25 70 95
%/cycle 18.2/5.7 35.2/12.0 62.1/25.1 68.6/29.2
kg/TWh 1.8/2.3 2.7/4.6 1.3/2.6 0.33/0.71
An analysis of activity changing for 129 I and the products of its irradiation is presented in Table 8.
Table 8. Different isotope contribution to activity after 129 I irradiation, Cu/kg
Isotope Loading Discharge
129 I
130m I
130 I
131 I
131m Xe
133m Xe
133 Xe
134m Cs
134 Cs
0.18
–
–
–
–
–
–
–
–
0.05
62 272.73
1.15+5
68.18
595.45
1.68
23,55
0.8
1.75
After cooling, year
3 100 1000
0.05 0.05 0.05
– – –
– – –
– – –
– – –
– – –
– – –
0.64 – –
– – –
Total 0.18 1.77+5 0.69 0.05 0.05
Contrary to 99 Tc, an irradiation of 129 I leads to the creation of e.g. 134m Cs while the activity of these
will define the activity of irradiated targets activities during some time (~30 years). Nevertheless, the
irradiation of iodine is also a rather efficient method to decrease the FP radioactivity. However, it is
necessary to pay attention to the fact that the irradiation products are also gaseous xenon isotopes
( 130 Xe, 131 Xe and 132 Xe) creating a rather high pressure in the used targets.
4.4 Palladium-107 transmutation
107 Pd has a half-life period of 6.5 × 10 6 years, and its production in the power reactor fuel
amounts: 1.54 kg/TWh for fast reactors and 0.78 kg/TWh for thermal reactors.
The effect of different moderators on 107 Pd transmutation efficiency is presented in Table 9.
230