• Nuclear Engineering and Technology
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• v.38 no.6
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• pp.489-504
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• 2006

A review has been made for the previous studies on safety of a geologic repository for high-level radioactive wastes (HLW) related to autocatalytic criticality phenomena with positive reactivity feedback. Neutronic studies on geometric and materials configuration consisting of rock, water and thermally fissile materials and the radionuclide migration and accumulation studies were performed previously for the Yucca Mountain Repository and a hypothetical water-saturated repository for vitrified HLW. In either case, it was concluded that it would be highly unlikely for an autocatalytic criticality event to happen at a geologic repository. Remaining scenarios can be avoided by careful selection of a repository site, engineered-barrier design and conditioning of solidified HLW. Thus, criticality safety should be properly addressed in regulations and site selection criteria. The models developed for radiological safety assessment to obtain conservatively overestimated exposure dose rates to the public may not be used directly for the criticality safety assessment, where accumulated fissile materials mass needs to be conservatively overestimated. The models for criticality safety also require more careful treatment of geometry and heterogeneity in transport paths because a minimum critical mass is sensitive to geometry of fissile materials accumulation.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.481-482
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• 2004

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.220.1-220
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.531.1-531
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.188-188
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• 1999

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.471-472
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• 1999

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.1325-1326
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• 2005

• Nuclear Engineering and Technology
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• v.50 no.8
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• pp.1277-1288
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• 2018

In this work, the reactor kinetics capability is used to compute the design safety parameters in a PWR due to complete loss of coolant flow during protected and unprotected accidents. A thermal-hydraulic code coupled with a point reactor kinetic model are used for these calculations; where kinetics parameters have been developed from the neutronic SRAC code to provide inputs to RELAP5-3D code to calculate parameters related to safety and guarantee that they meet the regulatory requirements. In RELAP5-3D the reactivity feedback is computed by both separable and tabular models. The results show the importance of the reactivity feedback on calculating the power which is the key parameter that controls the clad and fuel temperatures to maintain them below their melting point and therefore prevent core melt. In addition, extending modeling capability from separable to tabular model has nonremarkable influence on calculated safety parameters.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3694-3703
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• 2021

Instrumentation and Control systems (I&C) play a significant role in nuclear power plants (NPP) and other safety critical systems (SCS). We have conducted a rigorous study and discussions with experienced practitioners worldwide the strategy for the development of I&C systems to investigate the several aspects related to their dependability. We discussed with experienced practitioners that work on nuclear domain with the intention of knowing their approach, they use day-to-day for the development of such systems. The aim of this research is to obtain to provide guidance to those building I&C systems of NPP and have implications on state engineering licensure boards, in the determination of legal liability, and in risk assessment for policymakers, corporate governors, and insurance executives.

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.4150-4157
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• 2021

The supervision mode, monitoring basis and monitoring scheme of radiation environment monitoring concerning typical research reactors in China were investigated in this study. Summary and analysis were concluded of the present situation of supervised monitoring of radiation environment, such as monitoring objects, points, frequency and so on, based on the relevant data of monitoring points of four typical research reactors in China. Some experiences and existing problems were analyzed concerning the supervised monitoring of China's research reactors. Tips on topics related to strengthen the monitoring of radiation environment around the research reactors has noted.