Nuclear reactors small enough to be delivered on trucks are under development by Mitsubishi Heavy Industries.

Scheduled for commercialization within a decade, the 3 m tall and 4 m wide microreactors will weigh less than 40 tons, sized to fit inside a standard 40 ft cargo container. Minimal maintenance requirements will enable installation of these units underground to reduce risk from natural disasters or in remote areas lacking steady power supplies.

The microreactors will have a maximum electrical output of 500 kW, and multiple microreactor units could be combined to provide larger total power output. Based on an all-solid-state core concept, the microreactor uses a highly thermal conductive graphite-based material that removes heat from core without liquid coolant. The reactor core and all other equipment will be contained in capsule containers that are tightly sealed.

Mock-up tests are planned from 2023 to 2025 to verify the passive core cooling function by natural heat transfer without power source, water source, and operator action. Prototype testing will be performed from 2026 to 2030 to verify various features of the microreactor such as long-term operation, start-up/shutdown, and safety system functions, including passive shutdown and containment.

Highly enriched uranium will be used as fuel and will not require replacement during a service duration of approximately 25 years. Once the fuel is spent, the entire microreactor can be recovered.