Chapter 3
Development of Nondestructive Assay to Fuel
Debris of Fukushima Daiichi NPP (1):
Experimental Validation for the Application
of a Self-Indication Method
Jun-ichi Hori, Tadafumi Sano, Yoshiyuki Takahashi, Hironobu Unesaki,
and Ken Nakajima
Abstract We have proposed a new concept of the “self-indication method”
combined with neutron resonance densitometry (NRD) for nondestructive assaying
of the distribution of nuclear materials in the fuel debris of Fukushima Daiichi NPP.
To verify the method, we performed experiments using a 46 MeV electron linear
accelerator at the Kyoto University Research Reactor Institute. First, we measured
the area densities of gold foil 10, 20, 30, 40, and 50 μm thick by area analysis at the
4.9 eV resonance region. It was confirmed that the area densities of the target
nuclide can be determined by conventional NRD and the self-indication method
within 3 % accuracy, respectively. As the next step, we added a silver foil of 50 μm
thickness to a gold foil of 10 μm thickness and measured the area density of the gold
foil. It was shown that the contribution from the other nuclide (silver foil) can be
remarkably suppressed by applying the self-indication method. Finally, we have
demonstrated a nondestructive assay of nuclear material using a mixture composed
of a natural uranium foil, sealed minor actinide samples of
237 Np and
243 Am.
The results indicated that the self-indication method is useful for assaying a mixture
of materials with high activity such as fuel debris.
Keywords Fuel debris • Neutron resonance absorption • Pulsed-neutron source
• Self-indication method • TOF
J. Hori (*) • T. Sano • Y. Takahashi • H. Unesaki • K. Nakajima
Research Reactor Institute, Kyoto University, 2-1010, Asashironishi, Kumatori,
Osaka 590-0494, Japan
e-mail: hori@rri.kyoto-u.ac.jp
© The Author(s) 2015
K. Nakajima (ed.), Nuclear Back-end and Transmutation Technology for Waste
Disposal, DOI 10.1007/978-4-431-55111-9_3
21
Development of Nondestructive Assay to Fuel
Debris of Fukushima Daiichi NPP (1):
Experimental Validation for the Application
of a Self-Indication Method
Jun-ichi Hori, Tadafumi Sano, Yoshiyuki Takahashi, Hironobu Unesaki,
and Ken Nakajima
Abstract We have proposed a new concept of the “self-indication method”
combined with neutron resonance densitometry (NRD) for nondestructive assaying
of the distribution of nuclear materials in the fuel debris of Fukushima Daiichi NPP.
To verify the method, we performed experiments using a 46 MeV electron linear
accelerator at the Kyoto University Research Reactor Institute. First, we measured
the area densities of gold foil 10, 20, 30, 40, and 50 μm thick by area analysis at the
4.9 eV resonance region. It was confirmed that the area densities of the target
nuclide can be determined by conventional NRD and the self-indication method
within 3 % accuracy, respectively. As the next step, we added a silver foil of 50 μm
thickness to a gold foil of 10 μm thickness and measured the area density of the gold
foil. It was shown that the contribution from the other nuclide (silver foil) can be
remarkably suppressed by applying the self-indication method. Finally, we have
demonstrated a nondestructive assay of nuclear material using a mixture composed
of a natural uranium foil, sealed minor actinide samples of
237 Np and
243 Am.
The results indicated that the self-indication method is useful for assaying a mixture
of materials with high activity such as fuel debris.
Keywords Fuel debris • Neutron resonance absorption • Pulsed-neutron source
• Self-indication method • TOF
J. Hori (*) • T. Sano • Y. Takahashi • H. Unesaki • K. Nakajima
Research Reactor Institute, Kyoto University, 2-1010, Asashironishi, Kumatori,
Osaka 590-0494, Japan
e-mail: hori@rri.kyoto-u.ac.jp
© The Author(s) 2015
K. Nakajima (ed.), Nuclear Back-end and Transmutation Technology for Waste
Disposal, DOI 10.1007/978-4-431-55111-9_3
21