REMOVAL OF RADIOCOBALT AND OTHER ACTIVATED CORROSION PRODUCT NUCLIDES FROM NPP WASTE WATERS BY HIGHLY SELECTIVE COTREAT ION EXCHANGE MEDIA

摘要

An extensive study program has been carried out investigate the basic ion exchange properties of the new CoTreat ion exchange media and to evaluate it's performance in simulated and real waste solutions. This paper will report a selection of results obtained in these studies. Basic studies carried out as batch experiments in 1.0 M NaNO{sub}3 background showed that radionuclide (57{sup left}Co, 54{sup left}Mn, 59{sup left}Fe, 65{sup left}Zn, 63{sup left}Ni) distribution coefficients (k{sub}d) were linear functions of pH. Reflecting the weak-acid nature of the exchanger, the k{sub}d-values were low in acidic solution, but rose to high values (k{sub}d > 100,000 ml/g) at neutral pH. Lab-scale batch and column tests carried out with real Floor Drain and Equipment Drain waters from several nuclear power plants (NPP) in Finland (Loviisa NPP, Olkiluoto NPP) and in the US (Diablo Canyon NPP, Ginna NPP) indicated that very high processing capacities (50,000-500,000 l/kg) and decontamination factors (DF = 300-500) were obtainable provided that the solution is nearly neutral. For one of the samples (Loviisa NPP), two other commercial medias, active carbon (Norit RS) and an organic resin (Diphonix) were tested in parallel as a reference. Their efficiency was clearly lower than that of Co Treat.