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  • Author or Editor: D. Vas x
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Abstract  

Within the last five years the International Laboratory of Marine Radioactivity at Monaco has organized seven intercomparison exercises worldwide on natural materials of marine origin comprising sea water (SW-N-2), sediment (SD-N-1/1, SD-N-1/2, SD-N-2), seaweed (AG-B-1) and fish flesh (MA-B-3/1, MA-B-3/2). Results on man-made (54Mn,60Co,65Zn,90Sr,99Tc,134Cs,137Cs,238Pu,239,240Pu,241Am) and natural radionuclides were collected and evaluated. Reference values were established for a number of them. In the paper are discussed various aspects of the intercomparison exercises.

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Abstract  

A method has been developed for the determination of63Ni in environmental samples. The samples are ashed and leached with aqua regia whereafter hydroxides are precipitated with ammonia, leaving Ni in the aqueous phase. Nickel is extracted as dimethyl glyoxime complex by chloroform and back-extracted with HCl. Finially, Ni is electroplated onto a copper disc from an ammonium sulphate medium at high pH. The radiochemical yield is determined by atomic absorption measurements of stable Ni before and after electrodeposition.Nickel-63 on the discs is measured by beta spectrometry using solid state ion implanted detectors and by using a conventional windowless anti-coincidence shielded GM gas flow counter. Using a counting time of 3000 minutes, the minimum detection limits were 8 and 1 mBq, respectively.The method was applied to a series of macroalgae (Fucus vesiculosus) collected at different distances from a nuclear power plant. There was a correlation between distance to the power plant and the63Ni concentration in the algae. The relationship between63Ni and60Co, as well as that between63Ni and stable nickel, was also investigated.

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