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Yoshioka, Kenichi*; Kitada, Takanori*; Nagaya, Yasunobu
Progress in Nuclear Energy, 82, p.7 - 15, 2015/07
Times Cited Count：1 Percentile：9.61(Nuclear Science & Technology)A reduced-moderation LWR has been developed for the reduction of spent fuel and for the efficient utilization of uranium resources. The streaming channel concept to improve the negative void reactivity coefficient is one of the features of the reactor. This concept makes the fuel assembly more heterogeneous. The geometrical heterogeneity makes azimuthal neutron flux distribution of fuel rods steep. To validate azimuthal neutron flux distribution calculation, we measured the distribution around fuel rods in reduced moderation LWR lattices. These measurements were conducted in NCA with the foil activation method. The core consisted of the central triangular tight lattice zone and the outer driver zone of a square lattice. A pile of polystyrene plates for simulating void fraction was installed into the triangular tight lattice. Azimuthal neutron flux distributions were deduced from the activity of these small foils measured with plastic scintillators. Measurements were compared to calculations by the MVP code with JENDL-3.3. It was found that calculations agreed well with measurements.
Yoshioka, Kenichi*; Kikuchi, Tsukasa*; Gunji, Satoshi*; Kumanomido, Hironori*; Mitsuhashi, Ishi*; Umano, Takuya*; Yamaoka, Mitsuaki*; Okajima, Shigeaki; Fukushima, Masahiro; Nagaya, Yasunobu; et al.
Journal of Nuclear Science and Technology, 52(2), p.282 - 293, 2015/02
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)We have developed a void reactivity evaluation method by using modified conversion ratio measurements in a light water reactor (LWR) critical lattice. Assembly-wise void reactivity is evaluated from the "finite neutron multiplication factor", 
, deduced from the modified conversion ratio of each fuel rod. The distributions of modified conversion ratio and on a reduced-moderation LWR lattice, for which the improvement of negative void reactivity is a serious issue, were measured. Measured values were analyzed with a continuous-energy Monte Carlo method. The measurements and analyses agreed within the measurement uncertainty. The developed method is useful for validating the nuclear design methodology concerning void reactivity.
Yoshioka, Kenichi*; Kikuchi, Tsukasa*; Gunji, Satoshi*; Kumanomido, Hironori*; Mitsuhashi, Ishi*; Umano, Takuya*; Yamaoka, Mitsuaki*; Okajima, Shigeaki; Fukushima, Masahiro; Nagaya, Yasunobu; et al.
Journal of Nuclear Science and Technology, 50(6), p.606 - 614, 2013/06
Times Cited Count：1 Percentile：10.59(Nuclear Science & Technology)We have developed an intra-pellet neutron flux and conversion ratio distribution measurement method. A foil activation method with special foils was used for the neutron flux distribution measurement. A 
-ray spectrum analysis method with special collimators was used for the conversion ratio distribution measurement. Using the developed methods, intra-pellet neutron flux distributions and conversion ratio distributions were measured in critical experiments on a reduced-moderation LWR. Measured values were analyzed with a deterministic method and a Monte Carlo method. The neutron flux distribution measurements and analyses agreed within the range of 1% to 2%. The conversion ratio distribution measurements and analyses were consistent with each other. We found that the measurement methods are useful for the validation of neutron behavior in a fuel pellet, which is known as micro reactor physics.
Yoshioka, Kenichi*; Yamaoka, Mitsuaki*; Umano, Takuya*; Kikuchi, Tsukasa*; Mitsuhashi, Ishi*; Kumanomido, Hironori*; Nagaya, Yasunobu; Okajima, Shigeaki; Kitada, Takanori*; Takeda, Toshikazu*
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