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Colloquium of NH group, Kyoto Univ.
Toshiyuki Gogami
2015/2/23
Paper introduction of:
Cosmic-ray muon radiography of UO2 fuel assembly
T.Sugita et al., Journal of Nuclear Science and Technology 51, 7-8 (2014) 1024-1031
再稼働しつつある原発
3.11 The accident of Fukushima NPP
①②③④
Need information of melted fuel for decommissioning of reactor
Difficult to access due to too high radiation level
Muon radiography
ミュオン透過法による炉内調査の開始‼
IRID ( 技術研究組合 国際廃炉研究開発機構 ) R&D topics; 2015/2/12
Muon radiography
1. Transmission method[ Energy loss Stop ]Mane, Egyptian pyramid, temple gate, volcano, caverns etc.
2. Scattering (displacement) method[ Coulomb scattering Scattering angle (displacement) ]Invented at Los Alamos National Laboratory
H.K.M.Tanaka et al., Earth Planets Space 62 (2010) 119-129
Transmission method
K.Takamatsu et al., Annals of Nuclear Energy 78 (2015) 166-175
At High-Temperature engineering Test Reactor (HTTR)
Transmission method
K.Takamatsu et al., Annals of Nuclear Energy 78 (2015) 166-175
At High-Temperature engineering Test Reactor (HTTR)
Scattering method
𝐿𝑖=𝑑𝑖 tan 𝜃𝑖(1+ tan❑𝜃𝑖0)
Depending on the radiation length !!
Paper which will be introduced
Toshiba Nuclear Critical Assembly
Experimental setup
Mini Muon Tracker (MMT) system576 sealed drift tubes (5 cm diameter, 0.9 mm aluminum wall)1.2 m lengthxxyyxxyyxxyy (12 layers)
MMT1MMT2
C.L.Morris et al., Applied Physics Letters 104 (2014) 024110
30 days of data taking
Cross section of NCA obtained by the scattering method
Results
4 cm40 cm
20 cm
4 cm
±2 cmで一致
Result comparison with Geat4 simulation
Application for Fukushima Daiichi
Geant4 simulation model
10 m
10 m
Challenge for the high rate gamma-ray background
Geant4 simulation model
10 m
10 m
20 μSv/h1000 μSv/h
FPGA trigger 50 μSv/h
7.5 cm thickness steel expects to be needed.
Results of the simulation
50% melted core + 60 cm diameter debris Clearly seen !!
Summary
Muon radiography
• Can be used for nuclear reactor investigation with resolution of 3 cm.
• Investigation of Fukushima Daiichi • Transmission method (1号機、 2015/2-)• Scattering method (2号機、 2015/10-)