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Uncertainty in transport factors used to calculate historical dose from 131I releases at the Savannah River Site.

During the 1950's, atmospheric release of 131I was one of the largest contributors to offsite dose at the Savannah River Site. Computer models used to estimate offsite dose involve the use of many parameters with wide ranges of uncertainty. The overall uncertainty in dose can be estimated by propagating the uncertainty of each parameter through the model. A major component of the calculational model can be solved for a given release scenario and condensed into a transport factor, which, when multiplied by the air concentration (or deposition) and the appropriate dose conversion factor, can be used to estimate a specific pathway dose. Uncertainties are estimated for the period of 1955-1961 for all parameters contributing to the 131I transport factor for each pathway. The overall transport factor including all pathways has ranges characterized by maximum-to-minimum ratios (95% to 5%) of about 40. The parameter shown to have the greatest impact on the transport factor calculation was the fraction of elemental iodine released.

Air Pollutants, Radioactive↗

The Chernobyl reactor accident: the impact on the United Kingdom.

I had originally thought that by this time, nearly 1 year after the Chernobyl reactor accident, I would be in a position to describe fully its impact on the UK in terms of radiation doses, economics and future emergency planning. However, only one of these is reasonably clear-the radiological impact. We shall continue our measurements, particularly those of activity in persons, and doubtless we shall refine our estimates of collective dose, but they are unlikely to change significantly. We can therefore be certain that the radiological impact on the UK was small and that the health effects will not be detectable. Predictions of the consequences of accidental releases of radionuclides have in the past, perforce, relied upon models of environmental transfer. Data on which the models are based were obtained from investigations of weapons fallout and of routine releases from nuclear facilities. The Chernobyl accident provided a situation of activity deposition that was well characterised in time and in geographical distribution, and measurements along environmental pathways will allow us to validate or refine our models. This accidental deposition reinforced the importance of some effects that we knew about-such as the importance of wet deposition-and will cause us to consider the need to take account of specific situations that we had not considered previously in adequate detail-in particular, the behaviour of radionuclides in upland ecosystems. The overall economic impact is not yet clear and, unfortunately, is unlikely to become so until all restrictions on the movement and slaughter of sheep are removed and the farmers have received compensation. The effect on international trade may never be quantified. Some international agencies are evaluating the consequences of Chernobyl and their reports will become available during 1987. International agreements on intervention levels are also still under discussion and it would be premature to speculate about the need for any fundamental revisions to Emergency Reference Levels and derived quantities. Similarly, we are aware of the need for revision of the national emergency plan, but we are awaiting the government decision on this. One effect of the Chernobyl accident, however, is clear: the public's awareness of radiation issues has reached a new height. Members of the public demand information and advice, and better means of communicating these must be provided. Advice to take some action may provoke unnecessary alarm, but advice that no action is required may be distrusted. We cautiously assume that any dose, no matter how small, has some deleterious effect and yet, in situations of accidental releases, we may tell the public that no actions are required to reduced doses that they may consider appreciable and avoidable. We clearly need to promote a better understanding of the nature and acceptability of the risk of radiation doses in such circumstances and we intend to do so.

Accidents↗

[The biological effects in animals related to the accident at the Chernobyl Atomic Electric Power Station. 1. The experimental model. The radiation loads on animals kept continuously under external and internal radiation exposure in the area of the Chernobyl Atomic Electric Power Station].

Irradiation conditions in which laboratory animals were kept in experimental laboratories of Chernobyl and Kiev after the accident at the Chernobyl A.P.S. are described. The data are presented on the spectral structural and activity of radionuclides in the diet as well as in the organs and tissues of the animals. The radiation loads have been estimated with regard to an external gamma component and the internal one contributed by the incorporated radionuclides. It has been shown that radiation doses received by the animals during their lifetime due to these contributions do not exceed units of cGy.

Accidents↗