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米田 政夫; 藤 暢輔; 田辺 鴻典*; 北村 康則*; 三澤 毅*
Annals of Nuclear Energy, 159, p.108300_1 - 108300_8, 2021/09
被引用回数：2 パーセンタイル：31.78(Nuclear Science & Technology)The rotation method is a novel method for detecting nuclear materials using a neutron source such as californium. In this method, while a neutron source is rotated rapidly nearby a measurement object, neutron measurement is carried out by synchronizing the rotation motion. If the object contains a nuclear material, as the rotation speed increases, the larger deformation of time distribution of neutron counts is observed, which in turn resulted to the detection of the nuclear material. In addition to its features of low cost and portability, this method is capable of detecting uranium that emits very few spontaneous fission neutrons. This study presents the fundamental principle of this method and its effectiveness for detecting nuclear materials through the experimental verifications.
鈴木 忠和
JAERI-M 7255, 30 Pages, 1977/09
座標回転法を用いて制約条件を持つ非線形最適化問題を解くプログラムが開発され、手法の安定性、収束効率に対する評価がなされた。座標回転法の特徴は直交座標系を常に目的関数が小さく(あるいは大きく)なる方向に回転させながら最適点を探索して行く直接探索法で、探索方向が多次元空間において自由に回転することから目的関数の等高線が深い曲がった谷を持つとき有効である。制約条件を持つ問題へのこの手法を適用するためにはR.R.AllranとS.E.J.Johnsenにより提唱された方法を改善して用いた。その方法は制約条件式を目的関数の中にぺナルティ項として付加した新しい目的関数を考え、その目的関数を制約条件無しの最適化問題として解くことに帰着させるものである。新しく開発されたプログラムは一つのサブルーチンとして最適化コードシステムSCOOPの中に組みこまれた。
米田 政夫; 田辺 鴻典*; 藤 暢輔
no journal, ,
For the social diffusion of low-cost and transportable devices for detecting nuclear materials, we have developed a novel approach called the active rotation method, which utilizes a rotating neutron source near the object being measured to detect nuclear materials. The device to rotate a neutron source can be produced at low-cost and it is compact. A neutron source is rotated with several thousand rpm at measuring, and it is possible to detect nuclear materials by confirming the deformation of the time-distribution spectrum obtained by a neutron detector. In addition to the rotation device, we have also developed a low-cost neutron detector utilizing water Cherenkov radiation. In the presentation, we will introduce this newly developed a rotation device and demonstrate its nuclear material detection capabilities. The measurement system consists of a rotation device and a water Cherenkov detector for a neutron detector. The measurement object is a polyethylene container containing 7 g of Pu-239. As a result of the experiment, we confirmed the successful detection of nuclear material using our device. The system is compact, transportable, and significantly less expensive than traditional methods, making it a promising solution for nuclear security applications.
