Investigation on Main Radiation Source at Operation Floor of Fukushima Daiichi Nuclear Power Station Unit 4
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
3 Japan Atomic Energy Agency, (765-1 Funaishikawa, Tokai-mura, Naka-gun, Ibaraki 319-1184, Japan (Current affiliation)
* Corresponding Author: firstname.lastname@example.org
Published online: 25 September 2017
Pulse height distributions were measured using a LaBr3 detector set in a 1 cm lead collimator to investigate main radiation source at the operation floor of Fukushima Daiichi Nuclear Power Station Unit 4. It was confirmed that main radiation source above the reactor well was Co-60 from the activated steam dryer in the DS pool (Dryer-Separator pool) and that at the standby area was Cs-134 and Cs-137 from contaminated buildings and debris at the lower floor. Full energy peak count rate of Co-60 was reduced about 1/3 by 12mm lead sheet placed on the floor of the fuel handling machine.
Key words: Unit 4 / Fukushima Daiichi / LaBr3 / pulse height distribution
© The Authors, published by EDP Sciences, 2017
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