Mitsubishi Heavy is developing a safer nuclear reactor for Japan • The Register


Japan is poised to change course on energy policy after the 2011 Fukushima disaster with a focus on developing safer nuclear reactors.

The country halted construction of new nuclear power plants after a tsunami hit the eastern prefecture, home to the Fukushima Daiichi nuclear power plant, resulting in the worst nuclear accident since Chernobyl in 1986. Today, many Japanese reactors are inactive.

In the pursuit of carbon neutrality by 2050 and energy security due to Russia’s war in Ukraine, the Japanese government is considering a return to “new generation nuclear reactors equipped with new safety mechanisms”.

With this change, a new partnership led by Mitsubishi Heavy Industries with four electric utilities – Kansai Electric, Hokkaido Electric Power, Shikoku Electric Power and Kyushu Electric Power – to develop an “innovative light water reactor based on existing units of the same type” to be launched in the mid-2030s, as reported by Nikkei Asia.

Kansai Electric Power said in a statement, “We have studied the design of a next-generation light water reactor with improved safety and economy, and are working with Mitsubishi Heavy Industries.”

The project relies on Mitsubishi Heavy’s pressurized light water reactor that has been used by all four electric utilities. It will be capable of producing between 0.6 million and 1.2 million kilowatts of electricity.

The focus is on improving the control rod drive mechanism, responsible for tuning the nuclear reaction, to halve production or get the reactor back up and running in 17 minutes, about a quarter of the time required by existing reactors.

Sturdiness is also crucial, with the design said to withstand natural disasters, terrorist attacks and plane crashes. “Companies want to reduce the likelihood of the reactor sustaining damage to less than 1% of current designs by installing it underground and fortifying the outer walls of the containment vessel,” Nikkei said.

Under the containment vessel, a “core catcher” will be installed to prevent the molten fuel from escaping in the event of a meltdown. Emergency power systems that can also be used to cool the reactor will be reinforced and installed on site.

Mitsubishi Heavy is also working on smaller, more efficient nuclear power plants capable of producing 0.3 million kilowatts, as well as high-temperature gas-cooled reactors to produce hydrogen.

Prime Minister Fumio Kishida’s “green transformation” council has also been tasked with examining how Japan’s existing reactors could be upgraded to safer light-water units. Light water reactors are cooled and moderated with ordinary water unlike those using heavy water (deuterium oxide, D2O).

Elsewhere, as the International Energy Agency does not believe the 2050 carbon emissions targets are achievable without nuclear power, there have been signs of innovation in small modular reactors (SMRs), notably in Britain, where Rolls-Royce secured funding to build power plants based on the design.

SMRs are much smaller than the current generation of nuclear reactors under construction and produce much less power. But what they lack in economies of scale, they make up for in modular design and offsite construction.

The International Atomic Energy Authority says that “prefabricated SMR units can be fabricated and then shipped and installed on site, making them more affordable to build than large power reactors, which are often custom designed for a particular location, sometimes causing delays SMRs offer savings in construction cost and time, and they can be deployed incrementally to meet growing energy demand.”

However, a study conducted by Stanford University and the University of British Columbia concluded that SMRs can generate up to 35 times more waste to produce the same amount of energy as a regular power plant. The research and methodology have been heavily contested by companies developing the technology.

Either way, a global increase in nuclear power could be on the cards as governments wake up to climate change and over-reliance on rogue states for their energy needs – as demonstrated by the Nord Stream gas pipeline crisis. ®


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