Methodology of the experimental study of the state of spent nuclear fuel on the bottom of arctic seas

A methodology of experimental simulation of the state of spent nuclear fuel that is situated on the sea bottom as a result of some catastrophes or dumping is developed. Data on long-term (more than 2000 days) experiments on the estimation of the ⁸⁵Kr and ¹³⁷Cs release rate from spent nuclear fuel (fragments of irradiated UO₂ pellets) were first obtained; these estimates prove the correctness of the hypothesis put forward by us in the early 1990s concerning an earlier ⁸⁵Kr release (by one order of magnitude higher than that of ¹³⁷Cs) as compared to other fission fragments in the case of the loss of integrity of a fuel containment as a result of corrosion on the sea bottom. The method and technique of the onboard ⁸⁵Kr and ¹³⁷Cs sampling and extraction (as well as the sampling of tritium, a product of triple ²³⁵U fission) and their radiometric analysis at coastal laboratories are developed. Priority data on the ⁸⁵Kr background in the bottom layers of the Barents and Kara Seas and the ¹³⁷Cs and ³H in these seas (state of 2003) are presented. Models necessary for the estimation of the dilution of the fission products of spent nuclear fuel and their transport on the bottom in accident and dumping regions are developed. An experimental method for the examination of the state of spent nuclear fuel on the sea bottom (1 expedition each 2–3 years) by the ⁸⁵Kr release into the environment (a leak tracer) is proposed; this release is an indicator of the destruction of a fuel containment and the release of products of spent nuclear fuel in the case of ²³⁵UO₂ corrosion in sea water.