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Japan’s Mitsubishi Heavy to develop safer nuclear reactor

Mitsubishi Heavy Industries’ next-generation nuclear power reactor could be in operation by the mid-2030s. (Illustration courtesy of Mitsubishi Heavy Industries)

Company partnering with Kansai Electric and three other energy companies

Mitsubishi Heavy Industries will work with four local power utilities, including Kansai Electric power, to develop a nuclear reactor with enhanced safety features.

As the Japanese government considers deploying next-generation nuclear power plants, Mitsubishi Heavy announced on Thursday that it plans to develop an innovative light-water reactor based on existing units of the same type. The company aims to launch the new reactor by the mid-2030s.

The plan kicks off efforts to realize Japan’s revised energy policy, which differs from the previous one that precluded construction of new nuclear plants after the earthquake and tsunami disaster that devastated eastern Japan in March 2011.

Mitsubishi Heavy and Kansai Electric will be joined by Hokkaido Electric Power, Shikoku Electric Power and Kyushu Electric Power. “We have been studying the design of a next-generation, light-water reactor with improved safety and economy, and are working with Mitsubishi Heavy Industries,” said Kansai Electric Power.

The project aims to introduce a reactor based on Mitsubishi Heavy’s pressurized light-water reactor that has been used by the four power utilities. It will produce 1.2 million kilowatts of electricity.

The companies are looking to improve the control-rod drive mechanism, which adjusts nuclear reaction, seeking to halve output or bring the reactor back online in 17 minutes — about one-fourth the time it takes with existing reactors.

Improving safety will be a key goal, with the new reactor designed to withstand earthquakes and other natural disasters as well as potential terrorist attacks — including aircraft crashes. The companies want to reduce the reactor’s probability of sustaining damage to less than 1% of current models by installing it underground and fortifying the outer walls of the containment vessel.

A “core catcher” will be placed under the containment vessel to prevent molten nuclear fuel from escaping in the event of a meltdown. Emergency power systems used to cool the reactor will also be bolstered and located on-site, according to the companies.

Many existing reactors cannot quickly change output levels, taking about an hour to halve output or bring themselves back online. The new reactor will be designed to speed up these operations.

The companies envision the reactor working in conjunction with renewable energy sources, kicking in when wind- or solar-generated electricity cannot meet demand.

Mitsubishi Heavy has recently stepped up efforts to make small, economically efficient nuclear plants with an output of 0.3 million kilowatts. It is also developing high-temperature, gas-cooled reactors to produce hydrogen. In addition, the company is assisting an emerging U.S. business that operates fast reactors powered by spent nuclear fuel.

Uncertainty in global energy markets has prompted Japan to rethink its nuclear power policy but there has been little progress, mostly due to the earthquake and tsunami on March 11, 2011 that shattered the eastern part of the country.

In August, Japanese Prime Minister Fumio Kishida instructed the government to study building next-generation reactors with improved safety features, or upgrading current reactors into safer light-water units.

Source: Nikkei Asia