A nuclear option for mines in the North
Westinghouse's eVinci microreactor could serve as a zero-carbon battery to power northern mines and communities North of 60 Mining News – May 6, 2022
Last updated 5/6/2022 at 9am
What if remote mines and communities across Alaska and Canada's North could plug into batteries the size of cargo containers that could deliver multi-megawatt levels of zero-carbon electricity for at least eight years without needing a charge?
This is the type of power source Westinghouse Electric is delivering with its eVinci microreactor, a 5-megawatt-electrical power module expected to generate heat and electricity at the United States Air Force's Eielson Base just outside Fairbanks, Alaska.
Most small modular reactors on the horizon are built as permanent power generating plants that are fundamentally scaled-down versions of the large reactors that deliver grid power around the world – albeit with some technological upgrades and safety systems built in.
eVinci, on the other hand, is a truly micro and modular system. Each 5 MW unit can be delivered in four shipping containers – one for each reactor, power conversion unit, heat exchanger, and controls module, and equipment for interconnections. These modules were purposefully designed to be easily and quickly delivered to remote locations such as northern mines and communities and installed in buildings similar to those that house the diesel generators that are a staple for delivering electricity across the north.
"This type of transportable design solves some key challenges we see in Alaska and remote markets in Canada," Michael Valore, senior director of advanced reactors at Westinghouse, said during an April 26 presentation at the Alaska Alliance offices in Anchorage, Alaska.
With each eVinci unit completely built at a factory, the installation and ramp-up to full delivery of clean and nearly silent electrical and heat generation only takes about 30 days. And much like batteries, the reactor units are simply swapped out for a recharged one when the specialized self-encapsulated fuel is depleted – which would be about every eight years for eVinci modules running at full capacity.
This is expected to be an ideal low-cost solution for remote arctic and subarctic regions, where cold and dark winters make other forms of zero-carbon energy such as solar and wind unfeasible for operations that sometimes need enough electricity to power a small city.
Westinghouse's eVinci microreactor, on the other hand, really likes cold weather where the larger temperature differential allows for more efficient generation of electricity.
"In Alaska, with well-sub-below temperatures for significant portions of the year, we could potentially exceed 6 megawatts," said Valore.
At the same time, each microreactor pumps out roughly 7 MW of thermal energy. The waste heat, which is about 350-degree-Fahrenheit after electrical generation, can be captured by a heat exchanger connected to the power conversion module and used to warm buildings or production processes. This essentially free byproduct of the clean and low-cost electricity being delivered by eVinci would be very useful during the winter months across the North.
Eielson, an Interior Alaska air force base that only sees about four hours of daylight and often dips to 40 degrees below zero during the darkest and coldest days of winter, would be an ideal locale for the electric and heat cogeneration abilities of the Westinghouse eVinci microreactor.
"Micro-reactors are a promising technology for ensuring energy resilience and reliability, and are particularly well-suited for powering and heating remote domestic military bases like Eielson AFB," said Air Force Deputy Assistant Secretary for Environment, Safety, and Infrastructure Mark Correll.
Sen. Lisa Murkowski, R-Alaska, who has been one of Congress' most avid proponents of small modular reactors, commended the Pentagon on its decision to install "smart, safe, and clean next-generation" energy in her home state.
"The implementation of micro-reactor technology will bring clean, and resilient energy opportunities that boost our economy and strengthen our national security infrastructure without the concerns of a large nuclear reactor," she said.
Northern nuclear mines
Mining companies are increasingly looking into ways to lower the carbon footprint of their global operations to net zero. This is a tall order for an industrial endeavor that has traditionally relied on diesel to power the large earthmoving machines that dig up and transport rock and generate electricity for the power-hungry processing plants.
While global mining companies are making strides in electrifying mining fleets and plugging mines into renewable energy sources in regions closer to the equator, such solutions are not readily available to northern mines that are often hundreds of miles away from the nearest electrical grid, and solar intermittency is more of an annual than daily event.
Generators that burn the same diesel as the earthmoving machines have traditionally been considered the best solution for generating power for mines in Alaska and Northern Canada, which often need as much electricity as a small city.
The Diavik diamond mine in Northwest Territories, for example, requires somewhere between 19 and 26 MW of electricity to operate, which is roughly the same as the NWT capital of Yellowknife, a city of around 19,000 people.
To ensure there is plenty of power at all times, this northern Canada operation has 11 Caterpillar diesel generators with the capacity to deliver around 50 MW of power, which are supplemented by three wind turbines that can generate about 6.9 MW of electricity on an ideal day. The overcapacity diesel gensets provide redundancy for maintenance and emergency, and the wind turbines help reduce the burning of diesel by about 10% on average.
According to Caterpillar, gensets the size of those used at Diavik burn about 175 gallons of diesel per hour when running at 75% capacity. At this rate, keeping the lights on at Diavik requires roughly 1.5 million gallons of diesel to be purchased, delivered, and burned each year.
It would likely take around seven or eight eVinci reactors, which require less redundancy due to the lack of maintenance downtime, to replace the diesel generators at this mine.
A 2021 feasibility study completed by Westinghouse and Bruce Power estimates that a single eVinci microreactor would reduce electrical generation costs by between 14% and 44%. Considering that diesel prices have risen steeply over the past year, these savings would be even higher today.
Westinghouse estimates that electrical costs from its very first commercial eVinci microreactor run about US25 cents per kilowatt-hour of delivered electricity over the eight-plus years of operation on a single charge. This is expected to drop to somewhere between US10 and 18 cents per kWh once increased production reduces the per-unit build costs.
"The first reactor is always by far the most expensive – whether it is a small one or big one, that is always the case," said Valore.
And the costs are anticipated to be even lower over the 20-plus years a mine is in operation due to the lower costs of subsequent units, which are swapped out like batteries.
These significant cost savings come with some even more substantial environmental benefits – a massive reduction in CO2 emissions and the elimination of the need to transport diesel for heat and electricity.
In mining scenarios, the Westinghouse and Bruce Power study determined that an eVinci microreactor with diesel backup could reduce carbon emissions by about 90%.
Having a zero-emissions baseload power source that also happens to be less expensive to operate than diesel generators opens the door for considering the idea of electric equipment to do the digging and hauling at northern mines.
While the implementation of battery-powered mining equipment is in its nascent stages, especially for surface operations, some of the world's largest mining companies are already swapping out diesel-burning haul trucks and digging equipment in places where solar, hydro, and other sources of low-carbon power are available.
Electric mining equipment does not make sense, however, if the operation needs to add diesel generators to plug them into. Adding a couple of zero-emission eVinci reactors to handle the extra load of charging and powering electric trucks and excavation equipment, however, would result in even less diesel being hauled and burned across the North.
Time will tell whether the economic and ESG benefits of installing microreactors at northern operations pencil out for mining companies.
Native and First Nations peoples that live in the remote areas of Alaska and northern Canada would also need to be comfortable with nuclear before this technology would be a viable option for powering mines and communities in the North.
How eVinci works
Westinghouse, which has safely been building and operating nuclear reactors around the world for more than 60 years, has designed eVinci to be a safe and resilient source of power with superior reliability and minimal maintenance, particularly for energy consumers in remote locations.
eVinci's safety and reliability are products of a relatively simple and nearly solid-state design.
The microreactor module itself only has one moving part, an outer control drum that surrounds the core. This drum either absorbs or reflects neutrons based on its position, which serves as a kind of thermostat for the reactor – the more neutrons being reflected, the higher the thermal energy the unit produces and the more it absorbs, the less energy produced. This drum can be rotated to shut down the reactor or to run it at full capacity, and everything in between.
Once the drum is rotated to the operating position and the reactor is generating heat, eVinci passively delivers thermal energy to the electrical and heat units. Also, the reactor is cooled without the need for water or pumps.
Instead, hundreds of heat pipes filled with sodium metal passively transfer heat away from the core at sub-atmospheric pressures.
As the reactor heats up, the sodium in these heat pipes that run through special graphite blocks vaporizes and flows away from the core to the heat exchange unit. As the sodium cools, the liquid is wicked back to the core with a wire mesh inside the heat pipe. This self-regulating system keeps the reactor cool and provides thermal energy that can be transformed into electricity without the need for either pumps or high pressure.
"This technology really doesn't have anything to manually control; it is basically a solid-state device with a single-shaft power conversion," Valore said.
The simplicity of the design is also what makes it safe.
"Even if a bad actor were to get to the controls, they only have an option to shut down," the advanced reactors energy systems director said. "We are literally only giving the operator the capability to manually start up and manually shut down."
Similarly sized research microreactors are already operating safely globally with appropriate levels of oversight and security at universities in major population centers.
The TRISO nuclear fuel that will be used to power eVinci reactors, which uses uranium pellets encapsulated by three layers of carbon- and ceramic-based materials adds an extra layer of safety.
After decades of development and testing, the U.S. Department of Energy has declared TRISO uranium to be "the most robust nuclear fuel on earth."
"Simply put, TRISO particles cannot melt in a reactor and can withstand extreme temperatures that are well beyond the threshold of current nuclear fuels," DOE wrote.
Valore said this meltdown-proof fuel has resulted in a massive step-change in the safety of nuclear.
To allay any concerns over the handling or storage of radioactive materials where eVinci reactors are operating, the fuel is never removed at the customer site. Instead, the eVinci reactor is like a battery that will be delivered fully charged with enough uranium to last eight years of operating the reactor at full capacity. When the fuel is depleted, Westinghouse comes in and swaps the microreactor unit with one fully charged with uranium. The depleted cell is brought back to a facility already set up and permitted to handle and store uranium, where it is refurbished and recharged.
Commercial by 2027
Having extensively tested all the critical individual parts and systems, Westinghouse Electric is now ready to finish the technology development and prepare a demonstration reactor.
The first eVinci demonstration reactor is slated to be installed at Idaho National Laboratory where it will be run through testing to gain final Nuclear Regulatory Commission approval for the microreactor design. Westinghouse says it has been working with NRC through every step of the eVinci design and testing. The Idaho testing will give the nuclear commission the final data required to sign off on the safety of the design.
In parallel, Westinghouse is advancing similar regulatory approvals in Canada. In March, the Canadian government announced that it is investing C$27.2 million (US$21.6 million) to support this effort.
"As our government moves swiftly with our green economic recovery, we are laying the foundation for a better and more prosperous climate-oriented future," Canada Minister of Innovation, Science and Industry François-Philippe Champagne said upon the March announcement of the investment. "Westinghouse's innovative technology will help deliver cleaner energy sources across Canada, especially in remote communities."
In the U.S., the eVinci testing and design certification is expected to be completed in 2026, which would enable Westinghouse to support the microreactor at Eielson in 2027.
This pilot was initiated in response to the Fiscal Year 2019 National Defense Authorization Act requirement to identify potential locations to construct and operate a microreactor by the end of 2027.
"This technology has the potential to provide true energy assurance, and the existing energy infrastructure and compatible climate at Eielson make for the perfect location to validate its feasibility," said Air Force Assistant Secretary Correll.
The Nuclear Regulatory Commission licensed microreactor at Eielson will be commercially owned and operated.
This pilot plant will give mining companies considering the potential of powering their operations with eVinci modules an opportunity to both see the microreactor in action and how these power units could be licensed, installed, and operated at mines.
Following the receipt of federal design approvals, the licensing of an eVinci reactor for any given site is expected to be much simpler and shorter than permitting a mine in the U.S. It is anticipated that a mining company could either own and operate its own eVinci reactors or utilize an independent operator.
With federal backing in both countries, eVinci could be ready to serve as the batteries to power mines in Alaska and northern Canada in about five years. The implementation of these microreactors has the potential to massively reduce the gallons of diesel shipped into and CO2 emitted from these mines that have few other options for zero-carbon energy. Reductions that could be multiplied by plugging electric mining equipment into what are essentially nuclear batteries that keep going and going for at least eight years.
CORRECTION: The rate for delivered electricity from the first commercial eVinci microreactor has been corrected to US25 cents per kilowatt-hour and US10 and 18 cents per kWh once increased production reduces the per-unit build costs. The previous version of this article incorrectly stated the rates per MWh.