This holds true even if no attempts at decontamination are made.
The contributions made by the different isotopes to the dose (in air) caused in the contaminated area in the time shortly after the accident.
This image was drawn using data from the OECD report, the Korean table of the isotopes and the second edition of 'The radiochemical manual'.
An example of a short-lived fission product is iodine-131, this can also be formed as an activation product by the neutron activation of tellurium.
In both bomb fallout and a release from a power reactor accident, the short-lived isotopes cause the dose rate on day one to be much higher than that which will be experienced at the same site many days later.
The releases from nuclear reprocessing plants tend to be medium to long-lived radioisotopes; this is because the nuclear fuel is allowed to cool for several years before being dissolved in the nitric acid.
The releases from nuclear reactor accidents and bomb detonations will contain a greater amount of the short-lived radioisotopes (when the amounts are expressed in activity Bq)).
This paper also reports details of the effect of potassium, ammonium and calcium ions on the uptake of the radioisotopes.
Caesium binds tightly to clay minerals such as illite and montmorillonite; hence it remains in the upper layers of soil where it can be accessed by plants with shallow roots (such as grass).
A paper has been written on the radioactivity found in oysters found in the Irish Sea, these were found by gamma spectroscopy to contain It is likely that the modern releases of all these isotopes from Windscale is smaller.
An important part of the Chernobyl release was the caesium-137, this isotope is responsible for much of the long term (at least one year after the fire) external exposure which has occurred at the site.
After release into the environment, radioactive materials can reach humans in a range of different routes, and the chemistry of the element usually dictates the most likely route.