Is the age of the micro reactor just around the corner?
(1) The race to develop micro reactors is heating up.
Micro reactors have been developed for military purposes as a source of electricity for nuclear submarines and warrior aircraft carriers.
(2) Like existing nuclear power, micro reactors do not emit carbon dioxide (CO2), a greenhouse gas, unlike coal- and natural gas-fired power plants, and are considered to be safe and economical.
It is expected to become a trump card for "decarbonisation", as the reduction of greenhouse gas emissions from renewable energy sources such as solar power alone is considered to be limited, and development cooperation is expected to be a theme at the Japan-US summit scheduled for 16 April 2021.
Micro reactors are also known as small modular reactors (SMRs).
These reactors are characterized by their large surface area relative to the reactor's volume, which makes it easier to cool the reactor.
3.
(1) A micro reactor is a unit that can be mounted on a trailer, and the main components are manufactured in advance at a factory before being installed at the site, thus reducing the initial investment and shortening the construction period.
This means that the initial investment and construction time can be reduced by less than 50 per cent, compared with LWRs, whose construction costs are often in excess of one trillion yen.
In addition to their main feature of being able to isolate and move only the reactors in the event of an accident, the reactors are expected to provide stable power generation and to supplement renewable energy sources, whose output is often affected by the weather.
Furthermore, it is envisaged that the power stations will be scattered over a relatively small area, so that the impact of any accident will be minimal.
Isolation could be achieved, for example, by helicopters or container lorries.
(2) Companies in many countries, including Japan, are working on the development of practical applications.
Hitachi Ltd. is developing a micro nuclear reactor with an output of 300,000 kilowatts at Hitachi-GE Nuclear Energy (Hitachi City, Ibaraki Prefecture), a joint venture with General Electric (GE) of the United States.
The company aims to commercialize the reactor in North America around 2030.
The company says the micro reactor can cool the reactor core without the need for an external power supply and operation even in the event of an emergency.
4. (1) Japanese electric power companies are also interested in micro reactors.
The Kansai Electric Power Co. (KEPCO) has included the introduction of micro reactors in its Zero Carbon Vision 2050, which it announced in February, and sees them as a promising technology for decarbonization.
(2) Decarbonisation has become an urgent issue, but it is not easy to achieve.
Even if the introduction of renewable energies progresses smoothly, the share of renewable energies in the power supply mix in 2050 is expected to be only 50-60% in many countries, including Japan.
(3) A combination of nuclear power plants that do not emit CO2 during operation would bring us closer to realizing this goal, but the accident at TEPCO's Fukushima No. 1 nuclear power plant in 2011 has not diminished public distrust of nuclear power.
As a result of the accident, more stringent safety measures are required, and the construction costs of light water reactors are much higher than before.
(4) Micro reactors are attracting attention because they are safer and cheaper to build than LWRs and have the potential to solve the problems of existing nuclear power plants.
The Japanese government is willing to support Japanese companies in overseas micro-reactor projects, although there are still issues to be resolved, such as dispelling mistrust of nuclear power plants and establishing a method of disposing of spent nuclear fuel.
Prof.PhD.& Dr. Kamuro, Associate Professor, California Institute of Technology, USA
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