High levels of a radioactive isotope were discovered in parts of Russia in September.
Prof. Malcolm Sperrin, Director of the Department of Medical Physics and Clinical Engineering, Oxford University Hospitals NHS Trust, said:
“It is important to place this in context. Ruthenium is very rare and hence its presence may suggest that an event of some nature has occurred. That being said, the natural abundance is so low that even a factor of 900 up on natural levels is still very low. Ru (106) is a beta emitter with a half-life of slightly over a year so the isotopic presence may persist for some time depending on many factors. One source of ruthenium is in the Urals where it is mined along with other chemically similar elements, but the naturally occurring Ruthenium isotope is Ru (102) and not Ru (106) hence it is unlikely that the detected isotope has arisen from mining activity unless refinement and isotopic isolation has occurred on-site. This is one possible source of the material.
“It is difficult to understand why if only Ru (106) has been detected that other isotopes more consistent with an accident have not been identified in coincidence with the Ruthenium. This therefore suggests that, unless the evidence changes, that this release is not as a result of a greater accident.”
Prof. Paddy Regan, Professor of Nuclear Physics, University of Surrey, said:
“The levels are not particularly high and the fact that the isotope (106Ru -> 106Rh ->106Pd) decay appears to have been measured in isolation, rather than with the usual cocktail of other fission fragment signatures suggests a leak from a fuel/reprocessing plant or somewhere they are separating the Ru, possibly for use as a medical radiopharmaceutical/diagnostic material.
“The decay half-life of 106Ru is just over 1 year and it is accompanied by a nice, clear set of discrete gamma-ray signatures which help to easily identify the decay of this particular isotope (actually, the decay of its daughter nucleus 106Rhodium).
“106Ru is a typical signature of nuclear fission waste material (i.e. it is created following the fission of either Uranium or plutonium) and is present in spent fuel rods etc. (The gamma ray signatures are actually from the 106-Rhodium decay which is the shorter lived radioactive daughter created following the decay of 106-Ruthenium). For ‘detailed info’ the signatures for this decay are in the table below.
“If it was a reactor leak or nuclear explosion other radioisotopes would also be present in the ‘plume’ and from the reports, they are not (other signature radioisotopes such as 144Ce, 137Cs, 125Sb, 95Zr/95Nb and related).”
|106Ru||374 days||to 106Rh (gammas follow 106Rh decay)||428.4 (3) ; 511.8 (1000) ; 616.2 (37); 621.9 (487) ; 873.5 (22) ; 1050.4 (76) ; 1062.1 (2); 1128.0 (20); 1194.5 (3); 1562.3 (8)|
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