Index > 2 Development of a strategy, implementation and execution program to remediate radioactively contaminated sites >

2.10.8 End of a long term stewardship

The length of the long term stewardship phase depends on the half-lives of the residual radionuclides of concern [IAEA-2006c], [USNRC-2003]. For some sites, where relatively short-lived radionuclides such as 137Cs and 90Sr are the problem, the period of stewardship can be of the order of hundreds of years. Where long-lived radionuclides, such as many of the isotopes of uranium, thorium and plutonium, are the problem, the stewardship period may have to last effectively for ever.

It can be noted that these considerations also become more and more important and receive increasing public attention in the case of ‘conventional contaminants’ such as heavy metals, persistent organic pollutants and other toxic or hazardous substances. The term ‘long term’ is interpreted differently in different countries.

Administrations in various countries have adopted for practical reasons certain time spans; thus a 1000 year basis may have been selected for engineering designs in this context.