Yoshiaki Oka, Sadao Uchikawa, and Katsuo Suzuki

Abstract 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.