• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.1-18
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• 2021

The criticality analysis of VVER-1000 mock-up benchmark experiments from the LR-0 research reactor operated by the Research Center Rez in the Czech Republic has been conducted with the MCS Monte Carlo code developed at the Computational Reactor Physics and Experiment laboratory of the Ulsan National Institute of Science and Technology. The main purpose of this work is to evaluate the newest ENDF/B-VIII.0 nuclear data library against the VVER-1000 mock-up integral experiments and to validate the criticality analysis capability of MCS for light water reactors with hexagonal fuel lattices. A preliminary code/code comparison between MCS and MCNP6 is first conducted to verify the suitability of MCS for the benchmark interpretation, then the validation against experimental data is performed with both ENDF/B-VII.1 and ENDF/B-VIII.0 libraries. The investigated experimental data comprises six experimental critical configurations and four experimental pin-by-pin power maps. The MCS and MCNP6 inputs used for the criticality analysis of the VVER-1000 mock-up are available as supplementary material of this article.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.14-18
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• 2020

Korea Atomic Energy Research Institute (KAERI) has carried out various neutronics experiments in the commissioning stage of the Jordan Research and Training Reactor (JRTR), and this paper introduces the results of first criticality prediction and experiment for the JRTR. The Monte Carlo Code for Advanced Reactor Design and analysis (McCARD) with the ENDF/B-VII.0 nuclear library was used for prediction calculations in the process of the first criticality approach, which was performed to provide reference for the first criticality experiment. In the experiment, fuel loading was carried out by measuring the inverse multiplication factor (1/M) to predict the number of fuel assemblies at the first criticality, and the first critical was reached on April 25, 2016. Comparing the first criticality prediction and experiment, the calculated and measured CAR (Control Absorber Rod) heights for the first criticality were 575 mm and 570.5 mm, respectively, that is, the difference between the two results was approximately 5 mm. From this result, it was confirmed that JRTR manufacturing and various experiments had successfully progressed as designed.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1097-1104
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• 2023

A preliminary criticality analysis for novel pyrochemical apparatuses for the reprocessing of mixed uranium-plutonium nitride spent nuclear fuel from the BREST-OD-300 reactor was performed. High-temperature processing apparatuses, "metallization" electrolyzer, refinery remelting apparatus, refining electrolyzer, and "soft" chlorination apparatus are considered in this work. Computational models of apparatuses for two neutron radiation transport codes (MCU-FR and MCNP) were developed and calculations for criticality were completed using the Monte Carlo method. The criticality analysis was performed for different loads of fissile material into the apparatuses including overloading conditions. Various emergency situations were considered, in particular, those associated with water ingress into the chamber of the refinery remelting apparatus. It was revealed that for all the considered computational models nuclear safety rules are satisfied.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.6
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• pp.631-638
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• 2015

In this study, semiquantitative failure mode, effects, and criticality analysis (FMECA) for the reliability analysis of a solid rocket propulsion system is performed. The semiquantitative FMECA is composed of failure mode and effects analysis (FMEA) and criticality analysis (CA). To perform FMECA, the structure of the solid rocket propulsion system is divided into 43 parts down to the component level, and FMEA is conducted at the design stage considering 137 potential failure modes. CA is then conducted for each failure mode, during which the criticality number is estimated using the failure rate databases. The results demonstrate the relationship between potential failure modes, causes, and effects, and their risk priorities are evaluated qualitatively. Additionally, several failure modes with higher criticality and severity values are selected for high-priority improvement.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.575-581
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• 2011

A novel approach for analysis of criticality with respect to path and to activity in networks with fuzzy activity durations is proposed. After recalling the Yager ranking method, the relative degree of criticality of activities and paths are defined. An efficient algorithm based on path enumeration to compute the relative degree of criticality of activities and paths in networks with fuzzy durations is proposed. Examples of former researches are employed to validate the proposed approach. The proposed algorithm has been tested on real world project networks and experimental results have shown that the algorithm can calculate the relative degree of criticality of activities and paths in a reasonable time.

• Journal of the Korean Dietetic Association
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• v.8 no.2
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• pp.143-153
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• 2002

The purpose of this study was to verify the dietitian’s job description(2000) for dietitians working at schools. The survey was carried out for the frequency, criticality and difficulty of each job description with 4 point scales. The number of subject was 125 dietitians, who have been working over 3 years at their position. The results are following ; 1. Duties with high frequency and criticality were menu managements, purchasing, storage and inventory controls, food productions, meal services, managing equipments and facility, waste managements, sanitation managements and self promotions. 2. Duties with middle frequency and high criticality were human resources managements and financial managements. 3. Duties with low frequency and high criticality were nutrition assessment (life cycles, certain diseases, specific condition), medical nutritional theraphy, nutrition education and public health nutrition. 4. For difficulty, duties related food service had lower points than that of nutrition service.

• Journal of the Korean Dietetic Association
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• v.8 no.2
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• pp.121-131
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• 2002

The purpose of this study was to verify the dietitian’s job description(2000) for dietitians working at business and industry foodservice. The survey was carried out for the frequency, criticality and difficulty of each job description with 4 point. The number of subject was 39 dietitians, who have been working over 3 years at their position. The results are following ; 1. Duties with high frequency and criticality were menu managements, purchasing, storage and inventory controls, food productions, meal services, waste managements and sanitation managements. 2. Duties with middle frequency and high criticality were managing equipments and facility, human resources managements, financial managements, self promotions. 3. Duties with low frequency and high criticality were nutrition assessment (life cycles, certain diseases, specific conditions), medical nutritional theraphy, nutrition education and public health nutrition. 4. For difficulty, duties related food service had lower points than that of nutrition service.

• Journal of the Korean Dietetic Association
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• v.8 no.2
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• pp.132-142
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• 2002

The purpose of this study was to verify the dietitian’s job description(2000) for dietitians working at hospitals. The survey was carried out for the frequency, criticality and difficulty of each job description with 4 point scales. The subject was 62 dietitians, who have been working over 3 years at their position. The results are following ; 1. Duties with high frequency and criticality were menu managements, food productions, meal services and self promotions. 2. Duties with middle frequency and high criticality in food service area were purchasing, storage and inventory controls, waste managements, sanitation managements, managing equipments and facility, human resources managements and financial managements. 3. Duties with middle frequency and high criticality in nutrition service area were nutrition assessment (life cycles, certain diseases, specific condition), medical nutritional theraphy and nutrition education. 4. For difficulty, duties related nutrition service had higher points than that of food service.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.05a
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• pp.271-272
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• 2010

Sensitivity analysis by TSUNAMI clarifies the complex effects of key nuclides on the criticality probability quantitatively. As discussed above, the $K_{eff}$ of $UO_2$ fuel reaches the maximum value with 42w% concentration of intrusion water. The concentration of hydrogen affects the complexity of reaching criticality by its competition between the concentrations of $^{235}U$. Approximately if the weight percent of $H_2O$ in the mixture is less than 42%, the moderation effect of hydrogen surpasses its dilution effect on $^{235}U$. However, the importance of $^{235}U$ increases dramatically when the weight percent of water is bigger than 42%. In the sensitivity evaluation of $UO_2$ fuel employing TSUMAMI, there is a similar crosspoint of the sensitivity of $^{235}U$ and the sensitivity of $^1H$ where the criticality reaches summit. And the optimal water weight percent is determined to be 50%.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.19-29
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• 2021

This paper presents the validation of the MCS code for critical safety analysis with burnup credit for the spent fuel casks. The validation process in this work considers five critical benchmark problem sets, which consist of total 80 critical experiments having MOX fuels from the International Criticality Safety Benchmark Evaluation Project (ICSBEP). The similarity analysis with the use of sensitivity and uncertainty tool TSUNAMI in SCALE was used to determine the applicable benchmark experiments corresponding to each spent fuel cask model and then the Upper Safety Limits (USLs) except for the isotopic validation were evaluated following the guidance from NUREG/CR-6698. The validation process in this work was also performed with the MCNP6 for comparison with the results using MCS calculations. The results of this work showed the consistence between MCS and MCNP6 for the MOX fueled criticality benchmarks, thus proving the reliability of the MCS calculations.