Discussion

Session 4

The following additional points were made in the presentation of Paper 10,

Drs Morley and Dolphin of Harwell have just completed an independent review of the medical data relating to the ej|ects of fission products, including I . In their paper, presented at the IAEA seminar in Vienna on 27 March, 1969, they suggest a wooing level for the death rate due to I which is one-tenth of the previous value and is about the geometric mean between our upper and lower limits.

The population distribution model assumed tends to overestimate the delayed effects at a distance and to underestimate the early effects of close-in, for most practical situations, if siting were unrestricted. This is because the population density chosen (12 000 people per sq.mile) is low compared with that in the centre of older cities. It is more representative of the suburban sprawl surrounding many modern cities. At the larger distances population densities of 1 000 per sq.mile are more common. Allowing for the drop in dose with distance one would have to go out to over 1 000 miles to deliver the same total dose in man rem to the thyroid as would be sustained out to 60 miles at a population density of 12 000 per sq.mile.