Mitsubishi developing next-gen reactor that can adjust output in minutes

Mitsubishi Heavy Industries is developing a new type of nuclear reactor that will adjust its power output in approximately 17 minutes. This is unprecedented in the field as existing reactors need several hours to reach new output targets and stabilize there.

The power output of a nuclear reactor is the result of a complex set of relationships between fuel rod dipping distance, neutron beaming rates, water circulation, coolant and core temperatures, involvement of moderation systems, and more.

Changing one thing affects the other, and when the fission rate needs to go up or down, a set of careful adjustments has to accompany the act with precision and multiple confirmations. The changes in nuclear reaction rates need to be gradual and slow; otherwise, the reactor may get supercritical with no way to reverse it.

All of this constitutes a dire problem in power supply, as demand is constantly shifting, often pretty quickly. Because of this, nuclear reactors cannot be used alone in national grids, and they are always accompanied by fossil fuel and renewable energy harvesting solutions.

Mitsubishi’s novel reactor employs a new computer-regulated drive system for the control rods, which can make tiny adjustments on all the inter-related components of the reactor. As such, the system remains relatively stable while going up and down in power output, and the adjustment to a new output target can be completed within a short time.

The new reactor will also feature a safer containment vessel with double walls and other intelligent protection systems. Mitsubishi estimates the risk of breach to one tenth of the existing models, while the cost of construction for the new-gen unit remains the same, at around 600 billion yen ($5.3 billion).

Finally, the estimated date when the first nuclear plant of this kind will be ready for its first power-up isn’t before 2030, while its nominal output will range between 600 MW and 1 GW.