SIMULTANEOUS QUANTITATIVE-DETERMINATION OF H-3, C-14, P-32, S-35, CR-51, AND I-25 ON THE SURFACE OF A PAPER DISC USING COMBUSTION

A paper disc that retained H-3, C-14, P-32, S-35, Cr-51, and I-125 on its surface was combusted in a flow-type combustion flask filled with oxygen. The combustion products containing five radionuclides, except (CO2)-C-14, were collected by washing the inner wall of the flask with 0.5-m hydrogen peroxide containing excess NaHSO3. The (CO2)-C-14 that remained in the gas phase of the flask was introduced into another fl ask for absorption into an organic base solution. By determining the r adioactivity of both the solutions containing the respective radionucl ides by means of NaI(Tl) and liquid scintillation counters, the six ra dionuclides in the solutions were quantified. The detection limit of s urface contamination with this method was compared with the limit spec ified by Japanese law for the surface contamination of controlled area s.