[1N14-16] Radiation Metrology

[1N14] Estimation of Cs-137 contamination with pinhole gamma camera

*Hideo Hirayama^1,2, Katsumi Hayashi², Kohei Iwanaga², Kenjiro Kondo^1,2, Seishiro Suzuki² (1. KEK, 2. NRA)

Keywords:Gamma Camera, Cs-137, Contamination

The gamma camera is a useful measuring device for grasping the distribution of contamination, but estimation of the amount of contamination is not easy. If the total energy absorption peak count rate of γ-rays can be measured with a pinhole gamma camera, it is possible to estimate the amount of contamination from the distance from the source, the peak count rate and the information of direct γ-rays that can be calculated analytically . At the Fukushima Daiichi Nuclear Power Station, the relationship between the total energy absorption peak count rate by the gamma camera and the amount of contamination was examined using Cs-137 contamination estimated from the measurement of ambient dose equivalent rate. We report the results of the study and examples of the estimation of the amount of contamination by gamma camera using the obtained result.