Evaluation of a scheme for the pre-distribution of stable iodine (potassium iodate) to the civilian population residing within the immediate countermeasures zone of a nuclear submarine construction facility

Abstract

Background: The Barrow-in-Furness stable iodine (potassium iodate) tablet pre-distribution scheme was the first of its kind to be introduced to protect the population living around a fixed site nuclear facility in the United Kingdom. Pre-distribution schemes have attracted critical comment principally because the certainty of availability of potassium iodate tablets was unknown. This study aimed to establish the reliability of such a scheme.

Method: A structured interviewer-administered survey of a random sample of households served by the pre-distribution scheme was carried out using a standardized questionnaire.

Results: The ability of this scheme to provide stable iodine protection declined from 100 per cent to 60 per cent coverage over a period of two years for the designed worst-case demand (the ability to supply stable iodine tablets to all household residents normally living within the pre-distribution scheme zone).

Conclusions: Pre-distribution has value in areas where evacuation to a centre where stable iodine tablets are available or post-accident distribution to sheltering households is difficult. The value of such a scheme must be calculated against a predictable decline in its effectiveness. In implementing such a scheme it should be noted that this decline in coverage can be reduced by calculating the frequency with which tablet packs are redistributed to take account of this factor.