Investigation of Main Radiation Source above Shield Plug of Unit 3 at Fukushima Daiichi Nuclear Power Station
1 Nuclear Regulation Authority, 1-9-9, Roppongi, Minato-ku, Tokyo, Japan 106-8450
2 High Energy Accelerator Research Organization, 1-1, Oho, Tsukuba-shi, Ibaraki, Japan 305-0801
* Corresponding Author: firstname.lastname@example.org
Published online: 25 September 2017
Pulse height distributions were measured using a CdZnTe detector inside a lead collimator to investigate main source producing high dose rates above the shield plugs of Unit 3 at Fukushima Daiichi Nuclear Power Station. It was confirmed that low energy photons are dominant. Concentrations of Cs-137 under 60 cm concrete of the shield plug were estimated to be between 8.1E+9 and 5.7E+10 Bq/cm2 from the measured peak count rate of 0.662 MeV photons. If Cs-137 was distributed on the surfaces of the gaps with radius 6m and with the averaged concentration of 5 points, 2.6E+10 Bq/cm2, total amount of Cs-137 is estimated to be 30 PBq.
Key words: Unit 3 / Fukushima Daiichi / CdZnTe / pulse height distribution / EGS5
© The Authors, published by EDP Sciences, 2017
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