平成29年9月博士課程修了予定者論文発表会

平成２９年７月4日（火）　会場： 先導原子力研究所　北2号館6階会議室

開始時刻／ 終了時刻	発表者氏名	指導教員	論　　文　　題　　目
8：30 10：30	胡 宇超 （一般）	小栗慶之 木倉宏成	Development of evaluation method of the dose distribution of a syringe-needle type proton-induced X-ray source for prostate cancer therapy
An accelerator-based syringe-needle type proton-induced X-ray source was proposed to be applied as an alternative to the commonly used brachytherapy for treatment of prostate cancer. Focusing on an issue of this method that the dose distribution could be affected by various uninvestigated factors, the purpose of this research is to establish some experimental and calculational approaches to quantitatively evaluate the dose distribution. Firstly, using two semiconductor detectors, we measured the X-ray intensity at different angles, combining a PHITS simulation to analyze the effect of target shape on the X-ray angular distribution. The second experiment was a direct observation of the X-ray distribution by using liquid scintillator imaging method, during which a more adaptable Geant4 toolkit was introduced for numerical evaluation. Concerning the effect of the incident proton beam, in the third experiment, we measured the emittance of the proton beam and used it as an input parameter into an improved Geant4 simulation program to draw an intuitive 3D view of the dose distribution. Finally the fourth experiment was an improvement and combination of the second and third experiment, where we attempted to clarify the absolute value of dose under the experimental conditions.

開始時刻／ 終了時刻	発表者氏名	指導教員	論　　文　　題　　目
13：30 15：30	Yin Xiangbiao （IGP-(B)）	竹下健二 加藤之貴	Enhancement of Cesium Removal from Clay Minerals by Hydrothermal Treatment for Volume Reduction and Decontamination of Nuclear Post-accident Soils in Fukushima (福島原発事故で発生した土壌廃棄物の減容･除染のための水熱処理による粘土からのセシウム脱離促進)
Because of the Fukushima nuclear accident in March 2011, relative large amounts of radioactive Cs contaminated soils had been accumulated in Japan. Therefore, decontamination of these soils and their volume reduction become very urgent issues. Herein, Cs reversibility (adsorption and desorption) on typical clay minerals, which are responsible for Cs retention in soil, is systematically investigated in present study by combining sorption in different conditions and desorption with various cationic solutions at varied temperature. It was found that Cs desorption from clay minerals was significantly strengthened under the specific conditions such as hydrothermal treatment with multivalent cations. These results may open new ways to satisfactorily remediate the Cs-contaminated soils by achieving short retention time, low environmental stress, and good efficiency.

 

平成２９年７月5日（水）　会場： 先導原子力研究所　北2号館6階会議室

開始時刻／ 終了時刻	発表者氏名	指導教員	論　　文　　題　　目
8：30 10：30	Tuya Delgersaikhan （IGP-(A)）	小原　徹 加藤之貴	Supercritical transient analysis in possible fuel debris systems at Fukushima Daiichi NPS by multi-region approach based on integral kinetic model
Since the accident occurred at the Fukushima Daiichi NPS, the decommissioning activity has been going on continuously. One major part of the decommissioning is the retrieval of fuel debris formed inside the damaged reactors. During the retrieval process, the prevention and mitigation of possible criticality accident in fuel debris must be undertaken. In order to assist these activities, various criticality evaluations are expected to be performed. In this study, criticality accident involving fuel debris in various hypothetical scenarios was studied using the multi-region transient approach based on the integral kinetic model (IKM). In specific, the multi-region approach, its verification and validation efforts, comparison between the IKM and conventional one-point kinetics model, and transient analysis in hypothetical fuel debris systems are presented in this study.

開始時刻／ 終了時刻	発表者氏名	指導教員	論　　文　　題　　目
10：30 12：30	Simanullang Irwan Liapto （IGP-(A)）	小原　徹 加藤之貴	High Burnup Performance Small Pebble Bed Reactor with Accumulative Fuel Loading Scheme
Innovative concept of nuclear power plant is necessary to increase the efficiency of utilization of nuclear fuel due to the limitation of natural uranium resource. Pebble bed reactor (PBR) has the potential to fulfill the high efficiency of nuclear power plant. The PBR with an accumulative fuel loading scheme was chosen as the simplest fueling strategy of PBR. A Monte Carlo code MVP/MVP-BURN was used to simulate the neutron transport and burnup calculation. In addition, a new code has been developed to treat the accumulative fuel loading scheme of PBR. Several nuclear fuel materials have been performed in this reactor design. The optimum fuel composition of each fuel material was obtained to achieve high burnup performance with long operation period.

 

平成２９年７月7日（金）　会場： 先導原子力研究所　北2号館6階会議室

開始時刻／ 終了時刻	発表者氏名	指導教員	論　　文　　題　　目
10：00 12：00	田中 健一 (社会人)	千葉  敏 小原  徹	原子力発電所の廃止措置のための放射化放射能評価信頼性向上の研究
本研究では、原子力発電所の安全かつ合理的な廃止措置の計画及び実施に資する信頼性の高い放射化放射能評価の手法を研究開発した。本研究では、放射能の測定と計算を有機的に組み合わせ、評価対象の放射能の分布の特徴を把握し、現象的な理解に基づく評価を行うことで、十分な信頼性を達成する手法を確立した。また、原子力発電所に残存する放射能は運転停止後、時間と共に減衰していくが、放射化放射能計算の合理化を図り、放射能の分布の時間変化を視覚的に把握可能とした。この手法を用いた評価結果は、目標とする信頼性を達成し、また、視覚的な放射能分布の時間変化の情報は、効果的な廃止措置の計画の立案と実施時の合理的な安全確保を可能とした。