Westinghouse Sees a Tech Disrupter in its eVinci Microreactor

Kevin Clark  | Power Engineering  
November 23, 2022

About 40 miles southeast of Pittsburgh is the Westinghouse Waltz Mill site, part of the company’s expansive footprint in western Pennsylvania.

The Waltz Mill site provides maintenance services, testing and calibration for nuclear reactor servicing equipment. The pre-1960s facility once housed the first non-lab test reactor. Reactor coolant pump motors and components are refurbished there. It’s also home to Westinghouse’s robotics development efforts.

But the purpose of my visit was to see firsthand Westinghouse’s research and development (R&D) facility for its eVinci nuclear microreactor. The engineers I met on site during my visit in early November spoke excitedly about eVinci, which is in mid-design.

“I’ve been in this industry for many years, this is the most exciting time I feel that we’ve been in,” said Mike Shaqqo, Senior V.P. for advanced reactors.  

My visit came on the heels of Westinghouse’s $7.9 billion sale to Cameco and Brookfield Renewable Partners. The transaction, expected to be finalized in 2023, would bring Westinghouse’s reactors under Cameco, one of the world’s largest suppliers of uranium fuel; and Brookfield Renewable, one of the world’s largest clean energy investors.

“The acquisition reaffirms the important role Westinghouse and nuclear technology will play in the global clean energy transition and in helping the U.S. and other countries meet energy security goals,” said a Westinghouse spokesperson in a statement.

Westinghouse has invested time and effort into eVinci, a heat pipe reactor the company describes as more of a nuclear battery. The company touts the microreactor’s solid core and advanced heat pipes, which enable passive cooling and also allow for autonomous operation and load following.

The microreactor can generate 5 MW of electricity or 13 MW of heat from a 15 MW thermal core. Exhaust heat from the power conversion system can be used for district heating applications or low-temperature steam. eVinci could also be used in hydrogen production, maritime or industrial heat applications.

Westinghouse looks to off-grid applications like remote communities and mine sites as the entry market for eVinci. But the microreactor could also serve industrial sites or data centers. In remote locations, it could replace diesel as a power generating fuel, which is expensive to transport often hundreds of miles.

“We see [eVinci] as a tremendous advantage to replace diesel at mining and off-grid industrial locations, where they need that continuous and reliable energy source,” said Shaqqo.

A passive air heating system

The core design of eVinci is built around a graphite core, with channels both for heat pipes and TRISO fuel pellets. Hundreds of passive in-core heat pipes are intended to increase system reliability and safety.

Westinghouse engineers laud the microreactor’s passive cooling design. There are no pumps to circulate water or gas. The reactor’s heat pipes replace the reactor coolant pump, reactor coolant system, primary coolant chemistry control and all associated auxiliary systems.

Pipes embedded in the core transfer heat from one end to the other, where it is captured in a heat exchanger. For cooling, each heat pipe contains a small amount of sodium liquid as the working fluid to move heat from the core and is fully encapsulated in a sealed pipe.

Westinghouse said there is no need to replenish or circulate the sodium as it is completely sealed in the heat pipes. The company provided the diagram below for a visual of how the heat transfer works. Heat goes in the left side of the diagram, and the sodium turns into a vapor which travels to the end of the pipe where heat is removed. The sodium condenses back into a liquid and travels along the wick through capillary forces back to the hot end of the pipe.

The use of heat pipes in nuclear reactors may be new, but liquid metal heat pipe technology is mature.

“We know it works,” said Mike Shaqqo. He said that the Energy Department’s Los Alamos National Lab developed the initial concept of heat pipes and tested it extensively.

The only moving or mechanical parts in the reactor system are reactivity control drums, which manage the power level and allow absorber material to passively turn inward toward the core if power demand is reduced or lost, and turn a reflector material toward the core if demand increases automatically. Hence the term “nuclear battery.”

Because of the passive nature of eVinci, Westinghouse believes it would require only a small number of onsite personnel.

“If we’re sitting at a consistent power level, even [the control drums] are not moving, they’re stationary,” said Mike Valore, Westinghouse senior Advance Reactor Commercialization director. “The goal for eVinci,” he said, is to be “completely autonomous.”

Westinghouse says the encapsulation of the fuel and the graphite core blocks themselves provide barriers to fission product release. A canister containment subsystem (CCS) encases the entire core and is further fortified by a secure vault subsystem (SVS) to provide protection from external events.

Company engineers told me the fuel is coated with layers of silicone carbide that can handle temperatures higher than what the reactor and High Assay Low Enriched Uranium (HALEU) particles could produce.

More broadly, Westinghouse says the eVinci reactor and components are easily transportable, another reason why the company is targeting remote communities. They envision the plant being delivered in four truckloads: the reactor container, the power conversion unit (an open-air Brayton Cycle system), an instrumentation and controls container and miscellaneous support and equipment (like a heat exchanger to capture waste heat for district heating).

Fueling is planned to take place before the reactor is delivered to a site and would be removed when refueling is required.

What’s next

At Waltz Mill, engineers are still testing eVinci’s heat pipes to demonstrate their performance and validate analysis. The plan is for eVinci to have an 8+ year fuel cycle, so Westinghouse is testing for longevity, as well as how much heat can be extracted from the core.

Because of the often proprietary and sensitive nature of the design process, I’m not able to show or explain every detail.

But to this point, the company has a scaled-down prototypic cell of the eVinci reactor and used electric heaters to simulate temperatures that it would get from nuclear fuel. Westinghouse has tested the heat pipes at 800°C (1472°F).

“We were able to validate analysis and modeling codes, and we were able to show that our heat pipes in this cell were able to transfer the right amount of heat, with the way our analysis and modeling expect it,” said Valore.

The plan is for eVinci to undergo additional testing in the 2023-2025 timeframe using nuclear fuel at one of the national labs, most likely Idaho National Laboratory. From there, the plan is to finalize the reactor design and build a prototype for integrated testing at one of the national labs in 2026. Commercial deployment is targeted for 2027.

“I really believe it’s going to be disruptive at some point in time,” said Shaqqo.

As part of the eVinci licensing process, Westinghouse is working with regulators in both the U.S. and Canada.

In August, the company signed an agreement with the Canadian Nuclear Safety Commission to start a technical design assessment for eVinci. Last year, Westinghouse announced that it had filed a pre-application Regulatory Engagement Plan with the U.S. Nuclear Regulatory Commission.

Westinghouse and the Saskatchewan Research Council have an active agreement that would work to site eVinci in the province.

On the same day that agreement was signed, Penn State University announced plans to explore adding the microreactor with the goal of decarbonizing its State College campus in central Pennsylvania.

Westinghouse continues to be active in Alaska. The company said it has spoken with several end users and local utilities there.

“Our engineers are working as hard as they can to get this design completed and to get the testing started to get us to deployment,” said Shaqqo.

Westinghouse and the new nuclear industry

There has been talk of a nuclear renaissance for two decades. But several small modular reactors and micro reactors could achieve regulatory acceptance and deployment in the next decade. Some have remarked that we are moving from economies of scale to “economies of small.”

This combination of new nuclear tech, decarbonization goals and an increasing desire for energy independence following Russia’s invasion of Ukraine has sparked interest in nuclear.

President Joe Biden this year signed the Inflation Reduction Act (IRA) into law. The legislation includes several tax incentives for clean energy technologies, including advanced nuclear reactors.

Taxpayers will be able to choose from a technology-neutral production tax credit of $25/MWh for the first 10 years of plant operation or a 30% investment tax credit on new zero-carbon power plants placed into operation in 2025 or after.

The IRA also provides $700 million to support the development of a domestic supply chain for HALEU (high-assay low-enriched uranium) fuel.

For Mike Shaqqo, who grew up in the baseload nuclear industry thinking about grid-based reactors, the changes that eVinci could bring are exciting.

“We’re all part of making something important,” he said, by decarbonizing the electric power sector.

For more information read the Westinghouse Press Release or watch the video below: