Two of the world’s wealthiest men have put their vast resources behind what the nuclear industry calls small modular reactors (SMRs) in the quest for the perfect carbon-free energy source. TerraPower, founded by Bill Gates, and PacifiCorp, owned by Warren Buffett’s Berkshire Hathaway, are sponsors of the project.
The first SMR from TerraPower, the Natrium reactor project, will be built in Wyoming—the nation’s primary coal producer—at the very location that once housed a coal station, where the infrastructure for a steam-cycle power plant and distribution to the electrical grid already exist.
Last year, the state legislature passed a lawauthorizing utilities to replace coal or natural gas generation with small nuclear reactors and the US Department of Energy awarded TerraPower $80 million in initial funding to demonstrate Natrium technology; the department has committed additional funding subject to congressional approvals.
Clean and Green, But …
All energy sources have advantages and disadvantages.
Renewable sources of energy cannot provide necessary grid inertia, resulting in power that is unstable, poor in power quality, and susceptible to blackouts. This is why utilities must maintain a significant portfolio of baseload power plants—gas combined cycle, coal, and nuclear. Their rotating coils (generators) act as electrical “shock absorbers” to prevent grid perturbations.
Yet while baseload plants provide stability to greener energy sources—the 92.5% reliability rate for the US nuclear industry is unmatched by any energy source—they also introduce new problems: When 1,000 MW per unit is suddenly dumped to the grid from traditional baseload plants, that “extra help” significantly disrupts wholesale energy markets.
The proposed Natrium plant, a 345-MWe sodium-cooled reactor combined with a gigawatt-scale thermal energy storage system, actually solves both problems. It’s a steam-cycle generator that avoids grid perturbations, and it supplies a smaller, more manageable share of energy to the grid to preserve the economic balance.
Natrium’s technology is unique in that it stores excess energy in tanks of molten salt—as widely demonstrated around the world in the concentrated solar power industry. These reserves allow for short-term, 500-MWe power boosts that would supplement renewables in periods of high demand or on sunless, windless days.
What’s more, the smaller, more manageable boost in power (345–500 MWe compared with 1,000 MWe from traditional baseload plants) would stabilize small wholesale markets and allay perturbations in cost.
Natrium’s molten salt storage technology would also allow the plant to integrate seamlessly with renewable resources and could lead to faster, more cost-effective decarbonization. In addition, Natrium architecture separates and simplifies major structures, to condense construction costs and schedules.
“This is our fastest and clearest course to becoming carbon negative,” Wyoming Gov. Mark Gordon said. “Nuclear power is clearly a part of my all-of-the-above strategy for energy.” Chris Levesque, TerraPower’s president and CEO, said the demonstration plant would take about 7 years to build. “We need this kind of clean energy on the grid in the 2030s,” he told reporters.
What Once Was Old Is New Again
SMRs have been around since the 1950s when the US Navy started powering ships and submarines with mini reactors that were small, generated a lot of power in a compact footprint, and boasted unmatched reliability.
Building on that success, in 1958 the government financed Shippingport atomic power station in Pennsylvania, the first full-scale pressurized water reactor. In 1960, Dresden Unit 1 in Illinois became the first privately financed commercial reactor producing 192 MWe.
And with that, the nuclear industry was off to the races, with the promise that its output would be “too cheap to meter.”
The reality is that a wary public and exploding costs essentially killed the promise of new nuclear. Utilities couldn’t justify the initial outlay in expense brought on, in part, by tremendous governmental scrutiny and constrictive regulations following the accident at Three Mile Island in 1979 and the Chernobyl disaster in 1985. Neither could they fight negative public perception and a NIMBY (not in my backyard) stance against new construction.
The new generation of SMRs appears to have solved the initial cost problem. Construction costs are significantly lower than with a baseload nuclear unit [$1 billion for the Natrium technology vs. $27.5 billion (to date) for the AP1000series reactors under construction by Georgia Power]. And according to TerraPower the simplified design requires 80% less concrete than the current generation of reactors, and no elaborate emergency core cooling systems since the reactor is essentially sitting in a pool of its own coolant, at ambient pressure.
Clearly, the promise of small new nuclear has caught the interest of energy majors. The Natrium system is a TerraPower and GE Hitachi technology. Along with PacifiCorp and GE Hitachi Nuclear Energy, members of the demonstration project team include engineering and construction partner Bechtel, Energy Northwest, Duke Energy, and nearly a dozen additional companies, universities, and national laboratory partners.
Although the Natrium solution won’t provide a “perfect” source of energy, these companies are aiming to be on the right track with a carbon-free, low-cost, reliable energy source independent of sunshine, wind, or other whims of the weather.
