Deep Fission Unveiled Underground Reactor Concept

The California Deep Fission company, aims to locate 15 MWe pressurized water reactors (PWRs) about one mile (1.6 km) underground in a 76-inch borehole. The not implemented concept combines existing nuclear technology with the latest innovations in borehole drilling.

The reactor operates at the same pressure (160 atmospheres) as a standard PWR, and at the same core temperatures (about 315°C). As with a standard PWR, the heat is transferred to a steam generator at depth to boil water, and the non-radioactive steam rises rapidly to the surface where a standard steam turbine converts the energy to its electricity.

According to the data provided by the company, the reactor design does not envisage the moving parts at a depth, except for the control rods and coolant flow. Such design minimizes the need for maintenance, although the cables attached to the reactor enable the reactor to be lifted to the surface (it will take an hour or two only) for inspection. The new concept eliminates the need for large pressure vessels and containment structures, significantly reducing costs while enhancing safety, sustainability and operational efficiency.

The company said it has already completed the development of the conceptual design and technical documentation, submitted the regulatory engagement plan and conducted a conceptual design review meeting with the Nuclear Regulatory Commission (NRC) representatives.

The company has already started the analysis of the credible accidents and will analyze the reactor’s safety with the US regulator during the review of the design pre-application. The reactor will be covered with 1,5 km of the fresh water which will facilitate the emergency core cooling. Also, the reactor will have negative temperature coefficient, that is why at the overheating the reactor will be shutdown.

According to World Nuclear News