PROTECTING CRITICAL INFRASTRUCTUREPlan B: Keeping Nuclear Power Plants Cool in a Warmer, Drier Climate

By Kristen Mally Dean

Climate scientists and nuclear science and engineering experts at the U.S. Department of Energy’s (DOE) Argonne National Laboratory are joining forces to develop a plan B for nuclear power in Richland, Washington.

Scientists at the Lab will use Gateway for Accelerated Innovation in Nuclear (GAIN) funding from DOE to work with Washington’s Energy Northwest to inform the design and selection of future nuclear reactor cooling systems and their impacts on electricity cost.

Rick Vilim, manager of the Plant Analysis and Control and Sensors department in Argonne’s Nuclear Science and Engineering division, leads the effort with Rao Kotamarthi, senior scientist in Argonne’s Environmental Science division.

“GAIN vouchers enhance commercialization, and so we are working with Energy Northwest and a company called X-energy to know how an existing nuclear reactor plant and a proposed advanced reactor design should be configured for the local climate,” Vilim said.

According to Vilim, the most economical and best way to cool a reactor is to use a local, flowing waterway, such as a lake or a river, for ​“wet” cooling. This makes it possible to easily conduct heat away from a reactor and its cooling rods. That’s the current design employed at Washington’s nuclear power plant, the Columbia Generating Station in Richland. The Columbia Generating Station, which produces nearly zero greenhouse gas emissions, provides roughly 8% of the state’s electricity. It relies on a steady, cool flow of water from the Columbia River to keep its temperature down.

However, when considering construction of future nuclear power plants, Energy Northwest thought it prudent to develop a contingency plan if the river conditions change. Despite the well-established wet climate of its most populous city, Seattle, Washington state is quite temperate and arid east of the Cascade Mountain Range. There, Washington state is characterized by hot summers and cool winters. If changing climate models indicate that hotter, drier days lie ahead, more aridity will affect the volume, flow and temperature of the Columbia River.

“It’s a very commendable way of thinking about climate change — to plan before doing something versus not thinking about it and trying to adapt afterwards,” said Kotamarthi of Energy Northwest’s efforts. ​“A lot of people are confused about how to use the global climate data that exists, to make it actionable. At Argonne, we are working to provide very regional climate data in a form that industry can act on.”

Kotamarthi and his team have developed the expertise to perform impact analyses of risks from a changing climate, such as drought, heat waves and wildfire. The team can also provide translation of what that data means for local, immediate decisions and recalculate the data to demonstrate the effect 25 or 50 years from now. High performance computing resources at Argonne, such as the Argonne Leadership Computing Facility, a DOE Office of Science user facility, give Kotamarthi and his team the capability to develop very high-resolution regional scale climate model projections. Current model resolution is about 12 kilometers, but newer models in development are expected to get as specific as a 4-kilometer area.

Vilim brings a wealth of expertise in the engineering and design of nuclear reactors. He is well acquainted with the pros and cons of both wet and dry cooling designs. A dry cooling design, he explains, uses ambient air circulated across a reactor’s heat exchangers instead of relying on a river or lake to conduct heat away from a reactor, using fans or physics similar to those in a house chimney or car radiator. Cooler dry air from the environment passes across the much hotter exchanges of a reactor and forces hot air to rise away. As this happens, cooler air gets sucked in and lowers the reactor’s overall temperature.

“Dry cooling is not quite as efficient or as economical as wet cooling, but if wet cooling isn’t available, it’s your best option,” Vilim said.

A well-designed nuclear power plant has the potential to deliver significantly more carbon-free electricity. And understanding the role climate change plays today and in the future is important as public utilities and infrastructure planners develop plans to provide more energy.

“One of the biggest changes in the U.S. is going to be how precipitation like rain, snow and other precipitation events happen,” Kotamarthi said. ​“We may have really intense events with large amounts of rainfall in a very short time, followed by periods of no rain. These flash floods and flash droughts will make managing water a completely different task.”

Kristen Mally Dean is communications coordinator, Argonne National Laboratory. The article was originally posted to the website of the Argonne National Laboratory.