IMPROVEMENT OF ELECTRODE OF TRITIUM ENRIC HMENT CELL AND APPLICATION TO TRITIUM MONITORING IN ENVIRONMENTAL SURFACE-WATER AT SOUTH OSAKA AREA

The experimental studies on the improvement of electrode materials use d for the electrolytic enrichment of tritium and on the establishment of rapid procedure for the analysis of tritium and its application to tritium monitoring in environmental surface water at south Osaka area were carried out. The more efficient recovery rate and reappearance of tritium were obtained by the trial of the exchange of the electrode m aterial from nickel (Ni) to iron (Fe) at high current condition. Howev er, by considering the electrolytic corrosiveness of iron, a combined multi plate electrode of Fe(-)-Ni(+) (an effective surface area; 63cm( 2)) was adopted. In the case of such operational conditions that a cur rent density; 180 mA/cm(2) and a cooling temperature; 5 degrees C usin g a 100 mi glass cell inserted into the electrode, time required far d ecreasing the volume of sample solution from 100 ml to 15 ml was more than 22 h. In addition the recovery rate and the concentration ratio o f tritium were 90% and 6 times respectively. Then, the tritium activit y of the water sample could be counted rapidly with a relative countin g error of +/-20% for 4 h in a low level liquid scintillation counter. By the trial using the above mentioned method for the tritium monitor ing in environmental surface water at south Osaka area from 1986 to 19 92, it was proved that the tritium activities decreased to the natural ly producing level of tritium (BG) during this term and the decreasing half times of tritium concentration in this area by dilution were abo ut 4 years.