GMサーベイメータを用いた直接測定法による⁵¹Crの表面汚染密度の評価について

抄録

It is difficult to detect a low level contamination with ⁵¹Cr using a scintillation survey-meter because background counting rate of the survey-meter is high and emitted rate of λ-rays (0.320 MeV) from ⁵¹Cr is less than 10%. We examined whether a surface contamination with ⁵¹Cr can be detected directly with a GM survey-meter. As the result, the detection efficiency and detection limit of the GM survey-meter against the surface contamination were more than 0.6%(4π) and 4.6 13q/cm², respectively. From measurement of transmittance of radiations from ⁵¹Cr against poly (vinylidene chloride) seat, it became clear that the majority (about 98%) of detected radiations with the GM survey-meter is characteristic X-rays. These results show that the GM survey-meter can be used as a detector to check a surface contamination with ⁵¹Cr in controlled area.