By controlling coolant flow rate and temperature, electric power output can be adjusted independent of operation cycle, helping to stabilize the electric power grid
The HI-ABWR (Highly Innovative Advanced Boiling Water Reactor)*1 developed by Hitachi-GE Nuclear Energy, Ltd. (“Hitachi-GE”), with the technology for load-following operation*2 (Figure 1), can maintain stability of the electric power grid when the power generation capacity rate of renewable energy increases. In a boiling water reactor (BWR),*3 water and steam flow inside the reactor core, and the nuclear reaction is controlled by the quantity of void formed by the steam. The void quantity can be adjusted by the coolant flow rate, enabling electric power output to be adjusted by around 30% of the rated power (equivalent to the full electric power output of one thermal power plant). A problem with a conventional boiling water reactor, however, is that as the amount of nuclear fuel decreases at the end of the operation cycle, the adjustment range of electric power output becomes smaller. Hitachi has developed control technology that can increase the nuclear reaction by lowering the coolant temperature with maintaining nuclear reactor safety*4 (Figure 2). The combination of these technologies enables load-following operation independent of operation cycle.
Hitachi intends to continue working closely with Hitachi-GE, contributing to stable electricity power supply through the realization of HI-ABWR designed for power grid stabilization.
Figure 1. Example of load-following operation of a nuclear power plant(From HI-ABWR pamphlet)
Figure 2. Nuclear reaction control technologies at the beginning and end of operation cycle
*1 Highly Innovative ABWR (HI-ABWR):
: https://www.hitachi-hgne.co.jp/en/activities/advanced_reactor/hi_abwr/pdf/brochure_hi-abwr.pdf
*2 Load-following operation: Adjusting electric power output in a power generation station in line with the electric demand by consumers.
*3 Boiling water reactor (BWR): A type of light water reactor that boils coolant water inside the reactor pressure vessel and transfers the generated steam directly to a turbine for electric power generation.
*4 Maintaining safety: Operation within the licensed output (upper limit 100% rated power).
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