The Mainichi Shimbun answers some common questions readers may have about the development of small modular nuclear reactors.

       Question: What're these new nuclear power plants being developed overseas?

       Answer: In October, French President Emmanuel Macron announced that France would invest in the development of a new type of nuclear reactor: "small modular reactors." The development of small nuclear reactors is already well underway in the United States and other countries.

       Q: What kind of reactors are they?

       A: They are defined as having power output under 300,000 kilowatts. The ones made by U.S. company NuScale Power LLC have an output of 77,000 kilowatts. Most nuclear power plants to date have had large reactors with an output of more than 1 million kilowatts.

       Q: How big are these reactors?

       A: The one from NuScale Power is 4.5 meters across and 23 meters tall. Conventional reactors are about 40 meters in diameter and 60 meters high, so it is much smaller. The company is trying to boost total generating capacity by running six of the modular reactors together in the pool at a nuclear power plant. With subsidies of $1.355 billion from the U.S. government, their small reactors will be commercially operational in 2029.

       Q: What are some benefits to making reactors so small?

       A: The smaller size means less heat is emitted from the nuclear fuel, making it easier to cool. So, it is said that serious accidents are less likely.

       Q: Are they all better than existing models?

       A: There is a cost disadvantage. Conventional reactors have been made larger to increase power generation efficiency, but the smaller the reactor, the less efficient it becomes, making it harder to lower the cost of power generation. The question is whether it is possible to overcome these disadvantages by reducing the cost to build them.

       Q: Is Japan going to adopt these modular reactors?

       A: The Japanese government is conducting research, but has not said it will adopt the technology. Even small modular reactors produce nuclear waste, so public discussion will be needed if they are to be introduced.

       (Japanese original by Ei Okada, Science & Environment News Department)

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