Non-destructive assay of nuclear materials using a self-indication method

The integrity test applicable to TRU fuel containing MA with high radioactivity and high decay heat is important for safety. Neutron resonance transmission analysis is adapted for identification and quantification of nuclides in fuels by neutron time-of-flight measurement. In this work, a self-indication method was applied to the measurement of the transmitted neutron. The validation of the self-indication method was performed by using a pulsed neutron source and natural uranium samples at the KURRI-LINAC. The results show that the target areal density can be easily determined from the reduction of the counting rate around the resonances with and without sample. It was confirmed that the reduction ratio due to the neutron resonance absorption can be estimated to within 10%. The numerical estimation showed that the areal density of fuel material can be determined in the range from 10−6 to 10−2 (b−1) using multiple resonances and suitable thickness self-indicator

次世代型熱中性子炉核設計のための核データの検証に関する研究

京都大学0048新制・論文博士博士(エネルギー科学)乙第10879号論エネ博第23号新制||エネ||12(附属図書館)UT51-2002-B797(主査)教授 代谷 誠治, 教授 三島 嘉一郎, 教授 森島 信弘学位規則第4条第2項該当Doctor of Energy ScienceKyoto UniversityDFA

Nuclear Reactor Physics Experiments

First published in 2010, Reprinted 2018Preface [iv]List of Contributors [vi]Introduction to Kyoto University Critical Assembly (KUCA)1. General Description of KUCA Facility [1]1-1 KUCA Facility [1]1-2 Solid-Moderated-Cores (A- and B-cores) [2]1-3 Light-Water-Moderated Core (C-core) [3]1-4 Pulsed Neutron Source [4]1-5 Control Room [5]2. Details of the Light-Water-Moderated Core (C-core) [5]2-1 Overall Structure [5]2-2 Core Tank and Grid Plate [6]2-3 Fuel Plate and Fuel Frame [6]2-4 Core Configuration [10]Chapter 1 Approach to Criticality1-1 Fission Chain Reaction, Neutron Multiplication, and Approach to Criticality [13]1-1-1 Fission Chain Reaction [13]1-1-2 Neutron Multiplication [15]1-1-3 Inverse Count Rate and Approach to Criticality [16]1-2 Experiments [18]1-2-1 Neutron Detectors [18]1-2-2 Actual Procedure of Experiments [18]1-2-3 Determination of Infinite Reflector Thickness [22]1-3 Discussion [24]1-4 Preparatory Report [25]1-4-1 Numerical Simulation of Approach to Criticality Experiment [25]1-4-2 Two-Energy-Group Diffusion Calculation of Reflected Reactor [29]Appendix 1 [33]1A. Analytical Solution of Two-Energy-Group Diffusion Equation [33]1B. Solution for Core Region [34]1C. Solution for Reflector Region [36]1D. Determination of Critical Core Size [38]1E. Neutron Flux Distribution [40]Chapter 2 Control Rod Calibration2-1 Purpose [43]2-2 Principle [44]2-2-1 Reactor Kinetic Equation [44]2-2-2 Positive Period Method [45]2-2-3 Control Rod Drop Method [48]2-2-4 Compensation Method [50]2-3 Experiments [50]2-3-1 Core Configuration [50]2-3-2 Period Method Experiment [52]2-3-3 Rod Drop Method Experiment [52]2-4 Discussion [52]2-5 Preparatory Report [53]Appendix 2 [55]2A. Neutron Lifetime [55]2B. Delayed Neutron Data and Basic Parameters of KUCA [55]2C. First-Order Perturbation Theory [56]2D. Control Rod Calibration Curve [58]Chapter 3 Measurement of Reaction Rate3-1 Purpose [61]3-2 Principle [62]3-2-1 Features of Neutron Activation Detector [62]3-2-2 Measurement of Neutron Flux Using Activation Detector [63]3-2-3 Measurement of Radioactivity Using Gold (Au) Activation Foil [67]3-2-4 Detection Efficiency [69]3-3 Activation Reaction Rate Contributed by Thermal Neutron Flux [70]3-3-1 Neutron Spectrum in Reactor Core [70]3-3-2 Activation Reaction Rate Contributed by Thermal Neutrons [72]3-4 Experiments [81]3-4-1 Core Configuration [81]3-4-2 Equipment and Irradiation of Gold Wires and Foils [81]3-4-3 Measurement of Radiation of Gold Wires and Foils [83]3-5 Discussion [88]3-6 Preparatory Report [90]Appendix 3 [95]3A. Activation Reaction Rate by 4πβ-γ Coincidence Method [95]3A-1 Principle of 4πβ-γ Coincidence Method [95]3A-2 Absolute Measurement by 4πβ-γ Coincidence Method [97]3B. Outline of the HPGe Detector [98]Chapter 4 Feynman-α Method4-1 Purpose [101]4-2 Variance-to-Mean Ratio in Multiplication System [102]4-2-1 Decay Constant α [103]4-2-2 Y Value Expressed by Reactivity [104]4-2-3 Y Value [104]4-2-4 Asymptotic Behavior of Y Value [104]4-2-5 Y Value in a Critical System by Delayed Neutrons [105]4-2-6 Relationship between Power and Y Value [106]4-3 Experiments [106]4-3-1 Experimental Equipment [106]4-3-2 Experimental Methods [108]4-3-3 Data Processing [109]4-4 Discussion [110]Appendix 4 [113]4A. Derivation of Equations for Feynman-α Method [113]4A-1 Steady State [116]4A-2 Consideration of Delayed Neutrons [118]4A-3 Initial Correlation Correction, Spatial Dependence, and Fission Counter [118]Chapter 5 Pulsed Neutron Source Method5-1 Purpose [119]5-2 Principle [119]5-3 Experimental Equipment [126]5-4 Experimental Methods [126]5-5 Data Processing [127]5-6 Discussion [128

Assessing Energy Security Using Indicator-Based Analysis: The Case of ASEAN Member Countries

Using indicator-based assessment, this study examines the energy security of nine Association of Southeast Asian Nations (ASEAN) member countries to see how it has evolved over the past 12 years and identifies a country-specific energy security context for each country. The assessment uses 42 energy security indicators, which can be separated into five components: overall energy balance, socio-economic aspect, domestic energy resources, overseas energy demands and resources, and diversification of energy supply. The findings show different energy security situations among ASEAN member nations that are a result of national energy contexts, specifically uneven economic and energy infrastructure developments. The context, at a national level, affects the connotation of energy security and the interpretation of the indicators, which reflects different primary issues of concern regarding energy security. At the international level, due to the diversity, the interconnection of intra-regional energy markets could contribute to energy self-reliance of the region. Adversely, the difference could hinder the prospect of cooperation due to the lack of consensus on shared value

Japan’s 2014 Strategic Energy Plan: A Planned Energy System Transition

This study is a review and analysis of the Japanese government’s 2014 Strategic Energy Plan (SEP). As the first plan to be issued after the Fukushima disaster of March 2011, the 2014 plan incorporates policies that represent the most comprehensive and systematic changes ever proposed for Japan’s energy system. The study reviews the key elements of the plan, employing a framework that explains the nature and magnitude of the changes planned for Japan’s energy system and related institutions. The analysis demonstrates that the shock of the triple disaster opened up a window of opportunity in Japan’s policy environment for a fundamental change in energy policy, allowing for major reforms to the energy industrial structure and energy institutions. A unique aspect of this study is that it draws upon in-person interviews conducted with key government officials who were directly involved in the formulation of the SEP, providing new insights into Japan’s energy policy planning process and the drivers behind the planned reforms. Given the nature and magnitude of the potential changes implied in the SEP, this paper concludes that the 2014 SEP is best understood as a comprehensive blueprint toward a major planned transition of the Japanese energy system

Reactivity insertion transient analysis for KUR low-enriched uranium silicide fuel core

The purpose of this study is to realize the full core conversion from the use of High Enriched Uranium (HEU) fuels to the use of Low Enriched Uranium (LEU) fuels in Kyoto University Research Reactor (KUR). Although the conversion of nuclear energy sources is required to keep the safety margins and reactor reliability based on KUR HEU core, the uranium density (3.2 gU/cm3) and enrichment (20%) of LEU fuel (U3Si2–AL) are quite different from the uranium density (0.58 gU/cm3) and enrichment (93%) of HEU fuel (U–Al), which may result in the changes of heat transfer response and neutronic characteristic in the core. So it is necessary to objectively re-assess the feasibility of LEU silicide fuel core in KUR by using various numerical simulation codes. This paper established a detailed simulation model for the LEU silicide core and provided the safety analyses for the reactivity insertion transients in the core by using EUREKA-2/RR code. Although the EUREKA-2/RR code is a proven and trusted code, its validity was further confirmed by the comparison with the predictions from another two thermal hydraulic codes, COOLOD-N2 and THYDE-W at steady state operation. The steady state simulation also verified the feasibility of KUR to be operated at rated thermal power of 5 MW. In view of the core loading patterns, the operational conditions and characteristics of the reactor protection system in KUR, the accidental control rod withdrawal transients at natural circulation and forced circulation modes, the cold water injection induced reactivity insertion transient and the reactivity insertion transient due to removal of irradiation samples were conservatively analyzed and their transient characteristic parameters such as core power, fuel temperature, cladding temperature, primary coolant temperature and departure from nucleate boiling ratio (DNBR) due to the different ways and magnitudes of reactivity insertions were focused in this study. The analytical results indicate that the quick power excursions initiated by the reactivity insertion can be safely suppressed by the reactor protection system of KUR in various initial power levels and different operational modes (natural circulation and forced circulation modes). No boiling and no burnout on fuel cladding surface and no blister in the fuel meat happens and KUR is safe in all of these reactivity insertion transients if the reactor protection system of KUR works in its minimum degree

Quantitative Analysis of Japan’s Energy Security Based on Fuzzy Logic: Impact Assessment of Fukushima Accident

The Fukushima accident of March 2011 had great political, economic, and social impacts on Japan and marked a very important turning point in Japan’s energy policy. As the accident has also greatly exposed the vulnerability of Japan’s energy security, it is crucial to clarify the path that Japan should take to maintain and secure its energy security in case of any possible future outbreak that may threaten its energy security. For this purpose, we conducted a comprehensive and structural analysis of Japan’s energy security based on APERC’s 4As framework and by using fuzzy logic and the Fuzzy-DEMATEL method to quantitatively understand the performance of Japan’s energy security and how the Fukushima accident had impacted the performance. Our results demonstrate that Japan’s energy security has clearly degraded after experiencing Fukushima accident. In addition, the results of the structural analysis by the Fuzzy-DEMATEL method show that the most salient dimension in the 4As framework for improving Japan’s energy security is the “Availability” dimension, and for this purpose nuclear energy and renewables play very important roles in securing the future energy security in Japan; this is consistent with the current energy policy measures announced in the Strategic Energy Plan of 2014

Non-destructive assay of nuclear materials using a self-indication method

The integrity test applicable to TRU fuel containing MA with high radioactivity and high decay heat is important for safety. Neutron resonance transmission analysis is adapted for identification and quantification of nuclides in fuels by neutron time-of-flight measurement. In this work, a self-indication method was applied to the measurement of the transmitted neutron. The validation of the self-indication method was performed by using a pulsed neutron source and natural uranium samples at the KURRI-LINAC. The results show that the target areal density can be easily determined from the reduction of the counting rate around the resonances with and without sample. It was confirmed that the reduction ratio due to the neutron resonance absorption can be estimated to within 10%. The numerical estimation showed that the areal density of fuel material can be determined in the range from 10−6 to 10−2 (b−1) using multiple resonances and suitable thickness self-indicator

CRITICAL EXPERIMENT OF THORIUM LOADED THERMAL CORES AT KUCA (1) A NEW CRITICAL EXPERIMENT OF THORIUM LOADED CORE WITH HARDER NEUTRON SPECTRUM IN KUCA

In order to perform integral evaluation of 232Th capture cross section, a series of critical experiments for thorium-loaded and solid-moderated cores in KUCA had been carried out. In these experimental cores, H/235U nuclide ratio ranged about from 150 to 315, and 232Th/235U nuclide ratio ranged about from 13 to 19. In this study, a new critical experiment with Th loaded core in KUCA, which had about 70 of the H/235U ratio and 12.7 of 232Th/235U ratio, was carried out. As results, the excess reactivity was 0.086 ± 0.003 (% dk/k) and the keff was 1.0009 ± 0.0003, where the effective delayed neutron fraction was 7.656E-3. The keff was also calculated by MVP3.0 with different nuclear libraries. The respective calculations with JENDL-4.0, JENDL-3.3 and ENDF/B-VII.0 lead to 1.0056 ± 0.0086 (%), 1.0048 ± 0.0085 (%) and 1.0056 ± 0.0086 (%).On the other hand, the further MVP3.0 calculations, where only the 232Th cross sections were taken from JENDL-4.0, JENDL-3.3 or ENDF/B-VII.0 but all other nuclides were done from JENDL-4.0, were carried out to examine an impact of the difference of 232Th cross section among these nuclear libraries to the keff. The keff calculated with respective 232Th cross sections from JENDL-3.3 and ENDF/B-VII.0 was 1.0038 ± 0.0086 (%) and 1.0040 ± 0.0086 (%)