The New Nuclear
Small modular reactors may mean nuclear can compete with other on-site, compact forms of energy generation.
While nuclear power has been used in Canada for decades, no new nuclear power has been brought online since the 1990s and few governments (Ontario is among them) are considering building new nuclear facilities in the next twenty years.
But not every nuclear reactor is a 1,000-megawatt (MW) behemoth. Small modular nuclear reactors (SMR), with outputs rated up to approximately 300 MW run on a technology far more advanced than traditional mega facilities, and may soon compete as a source of power for mining and other operations.
The basic idea behind an SMR design is the same as a conventional reactor: use a self-sustaining fission reaction to produce heat and use that heat to produce steam and drive a turbine, creating electricity. But there are four major factors that have the potential to make new reactors preferable to conventional ones: cost, scalability, siting, and safety.
A significant hindrance to developing a large-scale nuclear facility is cost and not necessarily the overnight cost of developing the facility itself. Facility owners have to borrow large sums of money in order to get nuclear projects off the ground, which results in significant interest payments over time. Because construction of a nuclear plant can take between five and ten years, this means that governments have to wait a long time before the generation facility starts producing power and paying back the cost of developing the facility.
The scalability of the SMR technology lets it compete with large-scale nuclear plants on cost. For example, NuScale Power’s 45 MW SMR is specifically designed to be built twelve at a time, allowing reactors to come online as completed. The faster a unit can be brought online, the sooner the facility owner can start repaying the loans. Modular technologies also allow for the facility to grow with a community. This is a distinct advantage for areas where population density is expected to grow, as it allows for the facility to choose whether or not to grow based population projections.
The focus on factory-based construction is another potential cost cutter. The Westinghouse SMR, which is in part based on the technology used in the company’s AP 1000 full size reactor, is being designed to be factory built, with the components for the reactor shipped by rail or truck to the construction site.
This approach could have two significant advantages: time is saved during construction, and product quality is improved. By having the major components of the reactor assembled in a factory setting, it allows on-site construction crews to focus on building the support buildings and waste storage facilities, without being in the presence of potentially dangerous radioactive components. It also means that construction of the reactor will not be held up by weather or unforeseen engineering challenges.
The factory setting also improves the quality of the final product because every aspect of the construction of the reactor takes place in a highly controllable setting. Everything from the humidity in the factory to the precision metal cutting required can be controlled more effectively than if the reactor is built at the plant site.
With a twelve-unit plant and a two-year refuelling cycle, a NuScale reactor facility will require one unit to be refuelled every two months or so. According to Jose Reyes, NuScale’s co-founder and chief technology officer, this is a significant advantage over a large-scale reactor. Because it doesn’t involve taking 1,000 MW off the electrical grid, the system operator avoids buying replacement power on the spot market.
This isn’t an issue in Canada, where CANDU reactors rule, as they don’t have to be shut down during the refuelling process. But because Ontario is considering alternatives to CANDU technology, this could become an issue.
According to Reyes, the other significant advantage of SMRs is that it allows operators to have a permanent onsite crew for refuelling. Usually, the entire facility is shut down for refuelling, and 800 to 1200 temporary workers are hired. This involves substantial job and safety training and, in addition to the cost of the workers’ wages, the facility is not bringing in any money.
With just a specialized crew to do the work on a year-round basis, utilities could hire and train fewer workers, but only 45 MW of the generation capacity would be taken offline at any given time. This means that the facility continues to make money during refuelling and benefits from a specialized staff that will become more efficient over time.
Chris Deir is manager of nuclear business development in Canada for Babcock & Wilcox, where they build larger SMRs such as the 155 MW mPower reactor. He says the biggest draw of this design is that it’s not new technology. “There’s not a lot of risk associated with this type of design. We’re using proven technology and packaging it in a way that has never been [done] before.” Because of this, regulators aren’t examining the technology from the ground up, which should allow the mPower reactor to move through the regulatory system faster.
The design of the mPower reactor is a single unit that integrates the reactor core and steam generator into one 83-foot by 13-foot unit. That’s a significantly smaller footprint than a traditional nuclear plant. It could be buit on a site similar in size to a coal plant.
The design eliminates the pipe requirements for steam transfer and cooling which means, in the event of an accident, the cooling system for the reactor will not be compromised. This is a consistent trend for SMR designs, most of which feature a passive safety system that utilizes gravity or the complete submersion of the unit to ensure cooling is continuous. For example, the NuScale design relies on convection to cool the reactor. In the event of an accident or complete loss of power to the reactor, the technology is designed in a way that eliminates the possibility of an incident like the one in Fukushima, Japan.
This is possible because even though enough heat will be given off by the decaying uranium to cause the cooling water to boil, the volume of uranium present inside the chamber will cool at a rate that corresponds with the volume of water in the reactor chamber.
This is, of course, mostly theoretical at this stage. While a number of companies have started researching and engineering their designs, so far only one project in the United States is set to begin construction.
The nuclear industry still faces many of the same challenges as it always has: where to store nuclear fuel waste, how to rebuild public confidence after Fukushima, and, particularly in Ontario, how to ensure that nuclear projects are constructed on time and on budget.
But, if these smaller reactors are successful, it could open up a new list of possible uses for nuclear power generation. These more flexible technologies change where cities and regions can build nuclear plants and where they can be operated.
Douglas McCallum is a research associate at Actual Media, publisher of ReNew Canada and the Top 100 Projects report, which last year included one nuclear project.