Much attention was paid to the behaviour and modelling of CS 137 behaviour in the Chernobyl area. This is considerably different from that in many other places and reflects the very small amounts of clay and humus in the Ukrainian soil. They have much data and models derived from the behaviour of weapons fall-out. Caesium has proved much more mobile that we would have expected and this results in the ratio of internal to external dose being 10 to 15 times greater than it would have been in the UK, for example.
They have now performed about 1000 whole-body examinations of exposed people and find agreement between observed and calculated Cs levels in only about 3% of cases. The remaining 97% average about ten times lower than expected.
This may reflect a different phyical and chemical form of the caesium. In calculating the collective dose given in their report they have used the model value in order not to be accused of under-estimating the number of future cancer cases. In the event the observed collective dose may turn out to be some 10 times lower. Further observations over the next few years are needed to confirm this.
A number of suggestions for future workshops organised by the IAEA emerged.
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