BWR operating experience with axially two-zoned initial core

Through the past 14 years of BWR operation in Japan, improvement of the core has been aimed at increasing the thermal margin of the fuel and improving the load factor. Using Hitachi's original technology, an axially two-zoned fuel was developed along with a gray nose control rod in order to maintain fuel integrity. All of the fuels loaded in the initial core of Unit No. 2 of the Fukushima Dai-Ni Nuclear Power Station of the Tokyo Electric Power Co., Inc. (Fukushima 2-2) are axially two-zoned, and feature flattened (axial) power distribution and a low linear heat generation ratio. For the standard design of the BWR core fuel, a core similar to that in Fukushima 2-2 will be applied. Therefore, as the first experience of actual operation, this core will lay the foundation for future fuel design and core planning. (author)