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The Darlington Nuclear Generating Station. OPG would like to build a BWRX-300, a 300-megawatt small modular reactor designed by U.S.-based GE Hitachi Nuclear Energy on the site.Carlos Osorio/Carlos Osorio

The reactor Ontario Power Generation plans to build at its Darlington Nuclear Generating Station completed a prelicensing process with Canada’s nuclear safety regulator – an early milestone on the road to construction.

The Canadian Nuclear Safety Commission found no “fundamental barriers to licensing” the BWRX-300, a 300-megawatt small modular reactor designed by U.S.-based GE Hitachi Nuclear Energy. It’s the first such reactor to complete a two-phase preliminary process known as a vendor design review, which is billed as a way to assess whether a reactor developer understands Canada’s regulatory requirements and can meet them, but is not binding on the commission.

The review began in early 2020. Its findings offer an early indication of OPG’s prospects for obtaining a licence to construct the BWRX-300, which requires a construction licence and other approvals from the CNSC. (The utility applied for that licence in November, and the CNSC expects public hearings to take place in late 2024.)

The completion of the vendor design review “gives OPG a head-start on licensing,” Jonathan Allen, a spokesperson for GE Hitachi, said in a written response to questions.

CNSC staffers flagged certain aspects of the reactor’s design as requiring “further development,” one being that it must feature two independent shutdown mechanisms, “or else an alternative approach, with justification, is needed.” The CNSC also sought more information on severe accidents, radiation and fire protection, and radionuclide releases during fuel handling.

In a written response to questions, the CNSC said reactors are required to have two independent shutdown systems “to ensure that the operator remains in control of the nuclear reaction occurring inside the reactor.” It added that its regulatory framework is technology neutral: Vendors can propose alternatives “provided that safety can be maintained.” Mr. Allen wrote the BWRX-300 features “two separate and diverse means of inserting control rods in the reactor” to shut it down, and that GE Hitachi was “ready to address all of CNSC’s topics of interest.”

“From the list of areas needed for further development, it looks like [GE Hitachi] has some work to do,” said Allison Macfarlane, director of the University of British Columbia’s school of public policy, who served as chair of the U.S. Nuclear Regulatory Commission between 2012 and 2014. But she added the company is “experienced in getting technologies licensed” and accustomed to addressing regulators’ requirements, setting it apart from many small modular reactor vendors that have never licensed or built a reactor.

GE Hitachi markets the BWRX-300 as its simplest boiling water design since it began developing reactors in 1955, and promises capital costs up to 60 per cent lower per megawatt compared with large reactors. Cost-saving features include a compact design and limited on-site staff and security. Observers say the regulatory approvals process will go a long way in determining what actual costs will be, by imposing operating, maintenance and security requirements.

Canada’s first new nuclear power reactor in 30 years has embarked on a crucial review. Can it pass quickly?

Cost estimates for the Darlington reactor have yet to be revealed. At a conference held by the Canadian Nuclear Association in late February, Sashen Guneratna, managing director of investments at the Canada Infrastructure Bank, said that compared with alternatives such as renewable generation with long-term storage, or natural gas with carbon capture and storage, “the first SMR at Darlington is still a lot more expensive.”

In October the infrastructure bank provided a $970-million loan to OPG to finance preparation of the Darlington site. The bank, along with nuclear industry participants, hope subsequent BWRX-300 units will be cost-competitive with alternatives, and financed largely by private investors.

Although dozens of vendors promote small modular reactors, precious few have managed to partner with large utilities. OPG has not made a final decision to build the reactor, but expects to do so by the end of next year. (SNC-Lavalin has already signed on as the architect-engineer; Aecon will build the plant.) On Tuesday, OPG spokesperson Neal Kelly reiterated a previously announced schedule in which the reactor would be completed by 2028, and generating power the following year.

In addition to OPG, other utilities including Saskatchewan’s SaskPower and the Tennessee Valley Authority have expressed interest in building BWRX-300s, as have companies in Poland and Estonia.

Since 2016 the CNSC has initiated 11 vendor design reviews of these smaller reactors, several of which have completed the first phase. The CNSC performed similar reviews on several larger reactors earlier this century; some completed the process, but none were subsequently licensed for construction. OPG considered a few of those reactors as candidates for construction at Darlington a decade ago, but demurred.

At the Canadian Nuclear Association’s conference, CNSC president Rumina Velshi said during a speech that while her organization doesn’t want to impede small modular reactors, more than 70 reactor designs are being touted globally, and several in Canada.

“We must prioritize those designs that have a reasonable prospect for introduction in Canada, and in the order that they will be introduced,” she said. “Industry has a role, in putting forward a sensible number of nuclear technologies for deployment.”

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