Atomic Show #322 – Westinghouse’s eVinci micro reactor

The Atomic Show

Westinghouse’s eVinci is a 15 MWth, 5 MWe micro reactor. Westinghouse often refers to it as a nuclear battery.

Unlike conventional nuclear power plants, eVinci uses no water and doesn’t produce steam. The eVinci is not “just another way to boil water.”

There are no pumps in the system that moves heat out of the reactor. Instead, the system uses 24′ long heat pipes to transfer fission heat to a heat exchanger.

That device serves the same function as a combustor (burner) in a fossil fuel heated Brayton cycle gas turbine. Atmospheric air is compressed and sent through the heat exchanger where it gets hotter and more energetic. That hot, compressed gas gets expanded through a turbine, causing it to rotate. The rotating turbine is connected to a generator that produces electricity with an efficiency of about 33%.

An eVinci will use an open air Brayton cycle gas turbine like those that are in a wide range of commercial applications. Gas turbines are not only well-understood devices, but they have a diverse supply chain and an experienced workforce with tens of thousands of builders, operators and maintainers. They are often manufactured by the thousands.

In another departure from the conventional way of doing things, eVinci uses rotating control drums instead of insertable control rods to adjust core reactivity and operating temperature. Control rods are used during transport and to provide a secondary means of shutdown.

The fuel is TRISO coated particle fuel with high assay, low enriched uranium in the particles. The reactor operates in the thermal neutron spectrum with graphite as the moderator. The core isn’t in a pressurized fluid.

With its simple controls, small size and passive safety case, the eVinci is designed to be able to operate autonomously. Each core will last eight years or more.

Leah Crider, Westinghouse’s Vice President of Commercial Operations to the eVinci micro reactor, visited the Atomic Show to provide a system overview and to answer questions about the reactor, its history, its future, its applications and its potential impact on the energy market.

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