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Über dieses Buch

This book focuses on core design and methods for design and analysis. It is based on advances made in nuclear power utilization and computational methods over the past 40 years, covering core design of boiling water reactors and pressurized water reactors, as well as fast reactors and high-temperature gas-cooled reactors. The objectives of this book are to help graduate and advanced undergraduate students to understand core design and analysis, and to serve as a background reference for engineers actively working in light water reactors. Methodologies for core design and analysis, together with physical descriptions, are emphasized. The book also covers coupled thermal hydraulic core calculations, plant dynamics, and safety analysis, allowing readers to understand core design in relation to plant control and safety.



Chapter 1. Fuel Burnup and Reactivity Control

Nuclear fuel burnup and reactivity control are important points in the core design of nuclear reactors.
The fuel burnup analysis generally evaluates the time-dependent core power distribution and reactivity by solving burnup equations for the atomic density change of nuclides contained in the fuel as well as solving multi-group diffusion equations for neutron flux distribution and effective neutron multiplication factor. The core power distribution is necessary information for thermal-hydraulic and fuel designs.
The core design for reactivity control predicts reactivity change during reactor operation and determines its optimal control methods based on calculations of reactivity change with fuel burnup, fission product (FP) accumulation (poisoning effect), inherent reactivity feedback by temperature changes of fuel and coolant, etc. Among the general methods available for reactivity control, the insertion and withdrawal of neutron absorbers, generally referred to as control rods, is the approach usually taken for power reactors. A burnable poison, (a nuclide that has a large neutron absorption cross section) or a chemical shim (a neutron-absorbing chemical, usually boric acid, which is concentrated in the moderator or coolant) is employed for reactivity control depending on reactor types.
Fuel burnup and reactivity control based on fundamental theories with numerical expressions will be briefly reviewed in this chapter.
Shigeo Ohki

Chapter 2. Nuclear Reactor Calculations

The most fundamental evaluation quantity of the nuclear design calculation is the effective multiplication factor (k eff ) and neutron flux distribution. The excess reactivity, control rod worth, reactivity coefficient, power distribution, etc. are undoubtedly inseparable from the nuclear design calculation. Some quantities among them can be derived by secondary calculations from the effective multiplication factor or neutron flux distribution. Section 2.1 treats the theory and mechanism to calculate the effective multiplication factor and neutron flux distribution in calculation programs (called codes). It is written by Keisuke Okumura.
The nuclear reactor calculation is classified broadly into the reactor core calculation and the nuclear plant characteristics calculation. The former is done to clarify nuclear, thermal, or their composite properties. The latter is done to clarify dynamic and control properties, startup and stability, and safety by modeling pipes and valves of the coolant system, coolant pump, their control system, steam turbine and condenser, etc. connected with the reactor pressure vessel as well as the reactor core. The reactor core, plant dynamics, safety analysis and fuel rod analysis are described in Sect. 2.2. It is written by Yoshiaki Oka and Yuki Ishiwatari.
Keisuke Okumura, Yoshiaki Oka, Yuki Ishiwatari

Chapter 3. Light Water Reactor Design

Summary of development and improvement of light water reactors is described in Sect. 3.1. It is written by Yoshiaki Oka.
Design and management of a boiling water reactor (BWR) core is described in Sect. 3.2. It includes design criteria, design of fuel lattice and assembly, reactivity change with burn-up, control of power distribution and history, future trends in core design, core and fuel management. The author of the section is Sadao Uchikawa.
The core nuclear design of PWR is written in Sect. 3.3. The features of PWR core and basic criteria of PWR core design are presented. The design setup of core, fuel lattice, and fuel assembly follows. Control rods and chemical shim are described in the reactivity characteristics. Power distribution control is explained. In addition, evolution and future trend, core management, and fuel management are shown briefly. This section is written by Katsuo Suzuki.
Yoshiaki Oka, Sadao Uchikawa, Katsuo Suzuki

Chapter 4. Design of Advanced Reactors

Section 4.1 describes features of a fast reactor core and the procedure of the core design. The characteristics of reactivity and power distributions are explained in the nuclear design section and the reactivity control requirements are also explained in this section. The section of core thermal-hydraulic design explains the outline of the coolant flow allocation procedure and the evaluation methods of temperature distributions in a fuel subassembly. The author of Sect. 4.1 is Hiroo Osada.
Section 4.2 describes design of high temperature gas-cooled reactor (HTGR). HTGR’s cores consist of graphite internals and coated particle fuels that possess high temperature resistant. Helium gas is used as coolant that has high chemical stability in any temperature. High reactor outlet coolant temperature around 1,000 °C is possible for HTGRs with the high stable characteristics of graphite, fuel and coolant. High outlet coolant temperature enables high efficiency of electricity generation and broad utilization of HTGRs not only as electricity generation but also as a heat source for chemical industry. In comparison to LWRs, the outlet coolant temperature is high and difference between inlet and outlet coolant temperature is large for HTGRs. It results in different core design philosophy for HTGRs from LWRs. The core design of the High Temperature Engineering Test Reactor (HTTR) is presented as an example of HTGRs core design. The author of Sect. 4.2 is Kiyonobu Yamashita.
Hiroo Osada, Kiyonobu Yamashita


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