Measures to protect the population Main

Over the years, internationally recognised standards have been developed to limit exposures of the public to ionizing radiation from nuclear facilities of all kinds. These criteria can be met by incorporating particular features into the design of such facilities, and arranging for them to be sited and operated under rules and conditions to ensure compliance with the necessary standards. In general, by efficient pre-planning, even the most rigorous limits can be respected at a reasonably low cost.

The situation is different when, for any reason or combination of reasons, the pre-planned design and operational control measures fail and an accident occurs. The existing criteria no longer apply since the system has broken down and a new approach has to be adopted. The objective is to avert, as far as practicable, exposure to people in the area from future radiation doses. This limitation must be achieved through various methods, all of which may have some negative effects or costs of a health, socio-economic, psychological or political nature.

Many possible actions may be considered. Some are quite simple. If there is a minor radioactive release, people may be advised to stay inside their homes and keep windows and doors shut. At the other extreme, whole areas of land or entire towns may have to be evacuated and large quantities of food excluded from human consumption.

It is over-simplistic to assume that all measures which would reduce future dose are beneficial and therefore should always be fully implemented. For example, one of the measures to be reconsidered is that of resettling people elsewhere. Moving people to an area of lower radioactive contamination will probably reduce dose. Since future dose is considered to have a proportional effect on future levels of rise, relocation should reduce the risk of long-term radiation effects. However, it is known that the stress of extensive changes in lifestyle can have very serious psycho-social and even physical effects on people. A balance must be struck between potential reduction in dose and possible harm that might be avoided on the one hand and the possible detrimental and disruptive effects of the resettlement. The calculation of future dose avoidance, either by relocation or by food restrictions, is also not straightforward; single measurements of ground contamination do not translate into predictions of future dose because of factors such as the interaction of depositedmaterials with soils of different natures.

Many actions had to be taken quickly in the early days after the accident. Stable iodine tablets were issued, evacuations organized, and food restrictions imposed based on the best judgement that could be made on the available information. There is the opportunity now for longer reflection. As part of that process, a number of "decision conferences" were held towards the end of this international project with decision makers in the Republics and at All Union levels in the USSR to enable the issues addressed to be spelled out clearly and to clarify and summarize for the project the socio-economic and political factors that influenced the decision-making process in the affected Republics.

Comments by the projects teams

The unprecedented nature and scale of the Chernobyl accident obliged the responsible authorities to respond to a situation that had not been planned for. Thus, many early actions had to be improvised. The project teams were not able to investigate in detail many actions taken by the authorities owing to the complexity of the event. In those cases in which project teams were able to assess these actions, it was found that the general response of the authorities had been broadly reasonable and consistent with internationally established guidelines which prevailed at the time of the accident. Some measures could doubtless have been better taken or could have been more timely, but these need to be seen in the context of the overall response. It is all too easy, with the benefit of hindsight, to criticise actions which had to be carried out in response to a pressing situation.

The International Advisory Committee stated that the protective measures taken or planned for the longer term, albeit well intentioned, generally exceed what would have been strictly necessary from a radiological protection viewpoint. The relocation and food restrictions could have been less extensive. The extent to which such measures were implemented was not justified on radiological protection grounds. However, any relaxation of the current policy would almost certainly be counterproductive in view of the present high levels of stress and anxiety among inhabitants of the contaminated areas and people's present expectations. It is recognised, however, that there are many social and political factors to be taken into consideration and the final decision must rest with the responsible authorities. In any case, future modifications introduced should not lead to more restrictive criteria.

More specific comments included the observation that the relaxation of the criteria for food consumption should be considered as a preferable alternative to relocation when overall health, social and economic effects are taken into account. Continuing restrictions on the consumption of domestically produced food in the contaminated areas of concern imply, for some people, a serious deterioration in the quality of life. This may be remedied only by relocation to areas where an attempt can be made to resume the previous way of life if feasible. The relatively low cut-off levels adopted for food stuff restrictions may have exacerbated these problems. The study also found that the international confusion and misunderstanding about the appropriate level for such restrictions made matters much more difficult for the authorities. Clearer guidance is obviously necessary for the future.

Among more detailed findings in the report was a recommendation to improve the quality and quantity of information to the public. In particular, factors that may influence the acceptability to the local population of continuing to live in settlements in the contaminated areas of concern should be further identified and analyzed.

More realistic and comprehensive information should be provided to the public on comparitive levels of dose and risk. These risks should be compared with risks experienced in everyday life and with risks from other environmental contaminants such as radon and industrial pollutant emissions commonly found near large cities.