Neutron activation analysis (NAA) was used to determine
129I and the
129I/
127I ratio in bovine thyroid, moss, and river sediment samples collected in the vicinity of the Temelín nuclear power plant (NPP) in south Bohemia. The NAA procedures comprised pre-irradiation separation of
129I by combustion of the samples in the stream of oxygen at 1,000 °C and trapping the liberated iodine in a LiOH/(NH
4)
2SO
3 solution. Post-irradiation separation of
130I produced by the reaction
129I(n,γ)
130I was carried out by extraction of elementary iodine with chloroform followed by precipitation of PdI
2. Nondestructive, epithermal NAA was used to determine
127I employing the
127I(n,γ)
128I reaction. The results showed that mean values of
129I and the
129I/
127I ratio in the bovine thyroids varied from 22 to 61 mBq kg
?1 (dry mass) and 2.8 × 10
?9 to 5.4 × 10
?9, respectively. These values are close to the lower end of results reported from various regions non-polluted with
129I. No significant differences were found between
129I concentrations and the
129I/
127I ratios in the bovine thyroids collected prior to the start and after several years of operation of the NPP. The mean value and standard deviation of
129I in mBq kg
?1, dry mass and the
129I/
127I ratio in moss
Pleurozium schreberi were 23 ± 16 and 2.3 × 10
?9, respectively, whereas values of
129I in the river sediments were below 8–10 mBq kg
?1 (dry mass) after several years of the NPP operation.
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