Joint U.S-Canadian Advanced Nuclear Review May Focus on Terrestrial’s Molten Salt Reactor, NuScale SMR

Terrestrial Energy’s Integral Molten Salt Reactor (IMSR), a 195-MWe Generation IV nuclear technology, and NuScale’s small modular reactor (SMR) may be the focus of the first joint technical review by U.S. and Canadian nuclear regulators in a bid to boost their regulatory effectiveness as more advanced reactors and SMRs trundle toward commercialization. 

Rumina Velshi, president and CEO of the Canadian Nuclear Safety Commission (CNSC), suggested in remarks made on Nov. 13 at the International Framework for Nuclear Energy Cooperation’s Global Ministerial Conference in Washington that the two reactor designs may be the focus of the first technical reviews the regulatory body will undertake with its American counterpart, the U.S. Nuclear Regulatory Commission (NRC), as part of a collaborative effort established by a memorandum of cooperation this August. The regulators have said they want to increase the effectiveness and efficiency of their regulatory oversight, while ensuring safe and efficient development and deployment of advanced nuclear technology—which both governments are optimistic will play a significant role in a clean energy future.

Velshi said the collaboration had resulted in a “terms of reference” to guide work to “minimize duplications of effort and make regulatory reviews more efficient, less onerous, outcomes more predictable and resulting in increased safety at the end of the day.” Velshi also said the CNSC had discussed developing common guidance for review of license applications for SMRs, and the two regulatory bodies had “committed to share regulatory insights from technical reviews of designs starting with NuScale’s and Terrestrial Energy’s.” 

While the NRC acknowledged the collaborative effort is important, an NRC spokesman told POWER on Dec. 6 that “NRC staff continues discussions with our CNSC counterparts regarding the details of any actual cooperation on technical reviews for SMRs and advanced reactors.” However, those discussions “have yet to produce any specifics,” he said. 

Though the NRC could not confirm it, Terrestrial Energy on Dec. 4 announced that its IMSR had been selected “for the first joint technical review of an advanced, non-light water nuclear reactor technology.”

On the same day, NuScale Power Chairman and CEO John Hopkins said in an email that the company supported the NRC-CNSC collaboration on regulatory reviews. He noted, specifically, that the company “applauds the mention of NuScale as a technology of interest in this collaboration.” And he added: “We believe the long-term NRC-CNSC goal of achieving common review and acceptance is a critical step forward for the advanced nuclear industry, and we welcome working with both entities as NuScale progresses towards the approval of its SMR plant technology in the United States and Canada.”

Selection for an NRC-CNSC joint review would add to a series of recent high-profile achievements for Terrestrial, a company established in 2013, which today has offices in New York City; Oakville, Ontario, Canada; and Abingdon, Oxfordshire, UK. The company’s development of its molten salt nuclear technology is of high interest to the power industry because it promises to reduce costs and ramp up versatility and functionality of nuclear power—and revamp the economic question as it pertains to new nuclear. 

As Terrestrial Energy’s CEO Simon Irish told POWER in an interview in November, while talks continue with the NRC in preparation for pre-application interactions, the company has made notable progress within Canada’s vendor design review (VDR) process. It has also completed a siting study and prequalified to site a reactor at a Canadian federal laboratory, and it is leveraging the backing of major utilities both in Canada and in the U.S.—one of whom could eventually own and operate the first IMSR plant. For now, Irish said, the company’s “business ambitions” are to commission the first IMSR facility in the late 2020s. 

A Dead Heat for New Nuclear Design Commercialization—Mostly in Canada

The collaboration between the NRC and CNSC stems from a long history of exchanging information, working together, for example, on areas such as staff training, risk-informed licensing approaches, fuel qualification, materials issues, and molten salt chemistry. Both have expressed a critical need to “keep in step” with modernization initiatives and the technologies of the future. However, though the NRC and CNSC are separately evaluating design certifications for a variety of SMR technologies, Canada, which has already enacted a law to regulate activities involving the use of advanced reactor and SMRs, appears much further ahead. 

While VDRs are not required under Canadian law, at least three designs have to date completed the CNSC’s Phase 1 review, which involves a pre-licensing assessment of compliance with regulatory requirements. Terrestrial’s IMSR led the pack when it completed the Phase 1 VDR review in November 2017, and it remains the only reactor undergoing Phase 2 review, which involves an assessment to identify any potential fundamental barriers to licensing. The Phase 2 VDR, which began in October 2018 and will take two years to complete, is “a critical commercial step that precedes site selection and construction of the first plant,” Terrestrial explained. 

Other notable advanced nuclear technologies under review include Ultra Safe Nuclear Corp’s (USNC’s) MMR, a 5 MWe (15 MWth) micro modular reactor energy system design, which completed Phase 1 review on Feb. 7 and is now awaiting Phase 2 review, and ARC Nuclear Canada Inc.’s ARC-100 Liquid Sodium reactor, a 100-MW reactor design, which completed Phase 1 review on Oct. 1 and will now address questions or comments “in future engagement” with the CNSC. 

So far, in the U.S., only one SMR is undergoing design review by the NRC: Portland, Oregon–based NuScale Power, developer of a 60-MW light water reactor that can be installed in up to 12 modules. The NRC completed the second and third phases of review of the company’s SMR plant design in July 2019 and will likely complete all phases by September 2020. At least one other SMR vendor, Holtec International, is in the pre-application stage for its SMR-160, but the NRC notes only “limited pre-applications interactions,” have occurred. Another SMR vendor, BWXT, began but suspended pre-application interactions for its mPower design in 2014.

Among advanced nuclear technology vendors that have so far notified the NRC of their intent to engage in regulatory interactions are Westinghouse for its eVinci micro reactor; TerraPower for its MCFR molten salt reactor; KAIROS POWER for its KP-FHR reactor (also a molten salt reactor); X-Energy for its XE-100 modular high-temperature gas-cooled reactor; OKLO for its compact fast reactor; and Terrestrial, which submitted its intent in January, and with whom the NRC confirmed pre-qualification discussions are ongoing.

NuScale, meanwhile, told POWER on Dec. 4 that it now also plans to submit its design for VDR Phase 2 review to the CNSC by the end of 2019. That achievement would mark another notable milestone for the American developer, which is thought to largely lead the race to commercialize the first SMR technology in North America because it plans to put the first plant online at the Idaho National Laboratory by 2026. Construction of the first NuScale module, a project spearheaded by Utah Associated Municipal Power Systems (UAMPS)—an energy services interlocal agency of the State of Utah—could begin as early as 2023. 

An artist’s rendering of a NuScale SMR site. Courtesy: NuScale Power

Terrestrial Making Progress on Siting 

As Irish noted, Terrestrial already completed a siting study in February 2019 with Canadian Nuclear Laboratories (CNL)—a government-owned, contractor-operated subsidiary of federal Crown corporation, AECL, which is tasked with driving Canada’s nuclear vision. That month, Terrestrial also cleared the pre-qualification stage to site a reactor at CNL’s Chalk River Laboratories in Ontario, as part of a program that seeks to begin operation of an SMR on a CNL-managed site by 2026. 

In that contest, however, Terrestrial lags behind a partnership comprising Global First Power, Ontario Power Generation (OPG), and USNC, which is backing USNC’s 5-MWe (15-MWth) micro reactor. The partnership recently moved beyond CNL’s second stage for that program and was invited to participate in the third stage, which will involve discussions about land arrangements, project risk management, and contractual terms. Notably, the Canadian government this July also began an environmental assessment—the first in the nation for an SMR—for USNC’s MMR.

Meanwhile, on Nov. 15, CNL announced Terrestrial was one of the first four recipients of the Canadian Nuclear Research Initiative (CNRI), an initiative that seeks to accelerate SMR deployment by furnishing developers with funding and access to facilities and expertise within Canada’s national nuclear laboratories. Terrestrial’s work “will look at opportunities to utilize CNL’s existing facilities, most notably the ZED-2 reactor [sited at Chalk River], as well as develop new experimental capabilities related to molten salt reactors,” CNL said. 

USNC, which has proposed work to resolve technical questions relating to fuel processing, reactor safety, and fuel and graphite irradiation to support its 5-MW MMR is also a recipient of that initiative. Others include Moltex Canada, which is exploring converting CANDU fuel into a fuel capable of powering its Stable Salt Reactor; and KAIROS POWER, which is developing a tritium management strategy for its high-temperature fluoride salt-cooled reactor (KP-FHR) design. 

Burgeoning Interest in Molten Salt Technology

Owing in part to these developments, which are unprecedented for a privately developed Generation IV nuclear reactor design, Terrestrial has garnered a lengthening list of backers. 

OPG in May became the latest company to join Terrestrial’s “Nuclear Innovation Working Group,” a body that is advising Terrestrial during its Phase 2 VDR. Other members include Bruce Power, Burns and McDonnell, SNC-Lavalin, Kinectrics, Laker Energy Products, Promation, and Sargent & Lundy. The company is also bolstered by a remarkable “corporate industrial advisory board,” which comprises several utilities: Bruce Power, Duke Energy, Energy Northwest, Engie, NextEra Energy, OPG, PSEG, Southern Nuclear, and Tennessee Valley Authority. 

According to Irish, at least one member of that group may agree to be the owner and operator of a commercial IMSR. “We’re working with that group and explaining to them where we are for engineering, where we are with our licensing activities,” he told POWER in November. The company has also signed key contracts. In November, for example, it contracted UK-based Frazer-Nash Consultancy for engineering services related to the fabrication of the IMSR’s graphite moderator. 

Earlier in May, Terrestrial was also admitted to the Generation IV International Forum (GIF) as the only private company with that status.The company is now a formal member of the multi-national program’s Provisional Steering Committee of the Molten Salt System, which is one of the six reactor technologies that GIF is fostering with the expectation that they will be commercially deployed starting in 2030.

Terrestrial’s Hot Prospects

GIF notes that molten salt reactor technology was first studied more than 50 years ago—and two thermal-neutron-spectrum graphite-moderated concepts were demonstrated in the 1950s and 1960s at Oak Ridge National Laboratory in the U.S. Since 2005, modern research and development has focused on combining generic assets of fast neutron reactors with those relating to molten salt fluorides as fluid fuel and coolant. These concepts promise to extend resource utilization and minimize waste, as well as operate at low pressure and a high boiling temperature, it says.

Terrestrial’s IMSR uses a molten fluoride salt—which is a highly stable, inert liquid with robust coolant properties—for its primary fuel salt, as well as in a secondary coolant salt loop (without fuel). Notably, however, while the nuclear reactor design derives heavily from the Oak Ridge test reactors, it also borrows an “integral” architecture concept from the lab’s small modular advanced high temperature reactor (SmAHTR)—which means all its primary reactor components, including the graphite moderator, are integrated into a sealed and replaceable reactor core. This so-called “Core-unit” has an operating lifetime of seven years and is “simple and safe to replace,” the company says. Significantly, it also addresses challenges faced by the Oak Ridge reactors relating to the graphite moderator’s limited lifetime. 

Terrestrial Energy's IMSR Schematic
Terrestrial’s 195-MW IMSR power plant is a thermal-spectrum, graphite-moderated, molten-fluoride-salt reactor system that uses standard-assay low-enriched uranium (less than 5% U-235) fuel. Courtesy: Terrestrial Energy.

In the integral process—which takes place within the “Core-unit”—the fuel salt is diluted with coolant salt (consisting of fluorides such as sodium fluoride, beryllium fluoride, and/or lithium fluoride), and the mixture serves both as fuel and primary coolant. The mixture is pumped between a critical, graphite-moderated (thermal spectrum) core, and then through the integral heat exchangers to transfer its heat to the external secondary coolant salt loop. The secondary loop consists of bare diluent salts (without fuel salt added), and it in turn transfers its heat to another intermediate nitrate salt loop, which essentially serves as a barrier between the radioactive primary components and the end-users. The nitrate salt–heated steam generator finally produces steam that can be used for power generation or industrial applications. 

“What’s interesting about all six Generation IV systems—even though from a technology perspective they are vastly different—is that they share one thing in common: They operate at much higher temperatures. And that speaks to the opportunity for nuclear,” Irish said. 

Terrestrial’s IMSR operates at 700C, supplying steam turbines with superheated steam at 600C, which raises the system’s fuel efficiency to up to 48%. “A conventional reactor is stuck in the mid-30s, and if it’s a small conventional reactor, it may not achieve 30% at all,” said Irish. “If you operate at a much higher temperature, you can make power much more efficiently and you can do many more things with your nuclear reaction. You can provide high-quality industrial heat that can be used in industrial process applications that are very different compared to the steam generated electric power provision—which is pretty much the sole activity of nuclear energy today.” 

Those applications include support for petrochemical processes, including for production of hydrogen and ammonia, fertilizers, and plastics—and they could open up new end-users and sources of revenue. But industrial heat could also drive desalination, and even synthetic fuels, which could help decarbonize the transport sector, Irish said.

Last year, Terrestrial joined forces with Southern Co. and several U.S. Department of Energy national labs to study how efficiently and economically the IMSR can produce industrial-scale hydrogen. With the project completed, the company’s focus is now squarely on deploying the first commercial plant, and the company is now actively engaging with its supply chain and its utility group, he said. 

Irish: Nuclear Innovation Must Address Costs 

Asked about challenges the company could face in putting online the first-of-its-kind nuclear plant in a global power market that is increasingly inundated with cheap gas, renewables, and storage, Irish said he prefers to focus more on the opportunities. “It’s a sort of skiing analogy: Look at the gaps rather than the trees.” Simply put: “The opportunity for the nuclear industry is to recognize where it is in the context of the the market opportunity,” he said.

All clean energy technologies will play a role as the world moves toward decarbonization, he added, noting, “We need everything at our disposal.” Nuclear, specifically, offers the ability to deploy at scale, he said. “There are excellent case studies—real world examples, not expectations—that illustrate how quickly and effectively nuclear power plants can be deployed to completely decarbonize the grid,” he said, pointing to France and Sweden in the 1970s and 1980s, as well as to Ontario, the U.S., and the UK. 

But first, “Nuclear innovation must address one of the principle economic problems for nuclear—and that is cost,” Irish said. “Nuclear power as an investment is unremarkable. It does not attract private capital. Nuclear power using conventional systems today is in the market for government sellers and government buyers, because it is an unremarkable investment proposition.” Future systems “must be commercially transformative,” he said. 

All its potential considered, the IMSR could eventually deliver power at US$0.05/kWh, Irish suggested. “It’s not going to be the first plant, but this technology is capable, we believe, of competing with natural gas, competing with fossil fuels. That’s so important for global decarbonization because there are so many countries that are tied into coal because it’s a cost competitive, reliable energy source.” 

But if high-temperature reactors are commercially deployed, nuclear’s future role could be far more expansive, encapsulating non-traditional users of power, who are under the same “essential obligation to look at technologies that will make their industries clean,” said Irish. 

“Our system is also constrained by the laws of thermodynamics but for a machine operating at 700 degrees C. Our nuclear power plant operates at 47% to 48% thermal efficiency, far higher, and that means more revenues—because you can create 50% more kilowatt-hours—and, obviously that goes to your bottom line. Itʼs lifting your operating profits,” he said. “And that speaks to the commercial opportunity here—it’s something that’s commercially transformative.”

Sonal Patel is a POWER senior associate editor (@sonalcpatel, @POWERmagazine)

Corrections (Dec. 13, 2019): This version corrects the temperature at which Terrestrial’s IMSR operates from the previously stated 600C to 700C. It also corrects the currency in which the cost of power is presented to US$. POWER regrets the errors. 

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