Radiation characteristics of tritium plane sources for calibration of surface contamination monitoring instruments

Radiation characteristics of tritium plane sources have been studied for calibration of surface contamination monitoring instruments. On estimation of the radiation characteristics, three typical tritium sources of monomolecular layer, polymer and anodized aluminum were selected. Surface emission rates and energy distributions of the β-rays and X-rays emitted from the sources were measured using a windowless proportional counter. As a result, it turned out that the structural difference of sources influenced the calibration of instrument efficiency mentioned in ISO reports. And the suitable type of tritium source for routine calibration works was concluded. In addition, the efficiency of contamination source in the ISO reports was discussed for direct determination of tritium surface activity. (author)