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Structural integrity evaluation of irradiated LEU targets for the production of molybdenum‑99 using thermo‑mechanical behavior simulation coupled with pressure of fission gas release calculation

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Nuclear Science and Techniques 2022年第12期33卷 12-23页

作者： N.Mellel B.Mohammedi M.Salhi M.Dougdag S.Missaoui S.Hanini Birine Nuclear Research Center PB 18017200 Ain OusseraDjelfaAlgeria LBMPT UniversitéDr Yahia Farès 26000 MédéaAlgeria

Irradiated low-enriched uranium as target plates is used to produce,via neutron radiation and from the molybdenum-99 fission product,technetium-99m,which is a radio-element widely used for diagnosis in the field of nuclear medicine.The behavior of this type of target must be known to prevent eventual failures during radiation.The present study aims to assess,via prediction,the thermal–mechanical behavior,physical integrity,and geometric stability of targets under neutron radiation in a nuclear reactor.For this purpose,a numerical simulation using a three-dimensional finite element analysis model was performed to determine the thermal expansion and stress distribution in the target cladding.The neutronic calculation results,target material properties,and cooling parameters of the KAERI research group were used as inputs in our developed model.Thermally induced stress and deflection on the target were calculated using Ansys-Fluent codes,and the temperature profiles,as inputs of this calculation,were obtained from a CFD thermal–hydraulic model.The stress generated,induced by the pressure of fission gas release at the interface of the cladding target,was also estimated using the Redlich–Kwong equation of state.The results obtained using the bonded and unbonded target models considering the effect of the radiation heat combined with a fission gas release rate of approximately 3%show that the predicted thermal stress and deflection values satisfy the structural performance requirement and safety design.It can be presumed that the integrity of the target cladding is maintained under these conditions.

关键词： Irradiated LEU target Mo-99 production integrity evaluation Thermo-mechanical analyses Fission gas pressure

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integrity evaluation Method of GBAS Based on Extremum Distribution Model

Integrity Evaluation Method of GBAS Based on Extremum Distri...

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第三十九届中国控制会议

作者： He Li Yongjie Yan Xiaozhu Shi Jie Hu The 28th Research Institute of China Electronics Technology Group Corporation

The integrity evaluation of satellite navigation ground based augmentation system（GBAS） is the key of the whole performance evaluation process. Aiming to solve the problems of large sample demand and low evaluation accuracy in the integrity evaluation using frequency estimation method. This paper presents a method of GBAS integrity evaluation based on the extremum distribution model. This method starts from the integrity protection mechanism, uses the positive correlation between navigation positioning error and protection level to fuse data and takes the fusion data as the evaluation sample to improve the accuracy of evaluation. Then the feasibility of using the extremum distribution model to evaluate the integrity under the condition of limited samples is analyzed based on the extremum theory and integrity risk. Further, an error controlled fusion data extremum distribution model is established and the distribution parameters are estimated by the maximum likelihood estimation criterion. Finally, the integrity risk value of GBAS in the single approach guidance is derived from the distribution model. The processing result of Beidou GBAS sample data verifies the validity of this method.

关键词： Satellite navigation integrity evaluation Data fusion Extremum distribution model

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Data characteristic analysis and experimental research of BDS differential positioning error

Data characteristic analysis and experimental research of BD...

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第十一届中国卫星导航年会

作者： He LI YongJie Yan XiaoZhu Shi Jie Hu The 28th Research Institute of China Electronics Technology Group Corporation

The integrity of Beidou Satellite Navigation System(BDS) and its enhancement system is the key index to characterize the safe operation of navigation system and the key point of system performance eva

关键词： satellite navigation positioning error data characteristic integrity evaluation

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