Preface. Nuclear power plants need a constant supply of electric power to pump cool water into a reactor’s core.

Ninety percent of them, 54 plants, have at least one flood risk exceeding their design.

If flooding stops the power supply long enough, as happened in Fukushima, the core can overheat, melting through its container, as well as the nearby spent nuclear fuel pools which unlike the core, are in the open air, releasing deadly levels of radiation.

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Alice Friedemann  www.energyskeptic.com  Author of Life After Fossil Fuels: A Reality Check on Alternative Energy; When Trucks Stop Running: Energy and the Future of Transportation”, Barriers to Making Algal Biofuels, & “Crunch! Whole Grain Artisan Chips and Crackers”.  Women in ecology  Podcasts: WGBH, Jore, Planet: Critical, Crazy Town, Collapse Chronicles, Derrick Jensen, Practical Prepping, Kunstler 253 &278, Peak Prosperity,  Index of best energyskeptic posts

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Flavelle, C., et al. 2019. U.S. Nuclear power plants weren’t built for climate change. Bloomberg.

Turkey Point Nuclear Generating Station, 35 miles south of Miami, was designed to withstand a storm surge of 16 feet, according to documents submitted to regulators by its owner, Florida Power & Light Co. But the updated storm surge is expected to range from 17.4 feet to 19.1 feet at different parts of the plant. Last year, Florida Power & Light sought permission from regulators to extend Turkey Point’s operating license until 2053.

The Waterford power plant, a half-hour drive up the Mississippi River from New Orleans, was designed to withstand a maximum storm surge of 23.7 feet above sea level, according to documents provided to the NRC by Entergy Corp., which owns the plant. The company told regulators that a combination of storm surge and river flooding would create a maximum surge of 31.8 feet.

One of the largest gaps in storm surge protection is at Dominion Energy Inc.’s Surry Power Station, whose two reactors sit on a peninsula jutting into the James River just north of Norfolk, Va. The plant’s east side, which is most exposed to a potential storm surge, was designed to withstand a wall of water as high as 28.6 feet above sea level, Dominion told regulators. The company found that under current conditions, a storm surge combined with river flooding would bring a surge of as much as 38.8 feet.

The NRC directed the operators of the 60 or so working U.S. nuclear power plants to evaluate their current flood risk, using the latest weather modeling technology and accounting for the effects of climate change. Companies were told to compare those risks with what their plants, many almost 50 years old, were built to withstand, and, where there was a gap, to explain how they would close it.

That process has revealed a lot of gaps. But Gregory Jaczko, former chairman of the U.S. Nuclear Regulatory Commission (NRC) and others say that the commission’s new leadership, appointed by President Donald Trump, hasn’t done enough to require owners of nuclear power plants to take preventative measures—and that the risks are increasing as climate change worsens.

Ninety percent of plants, 54 of them, have at least one flood risk exceeding their design. Fifty-three weren’t built to withstand their current risk from intense precipitation; 25 didn’t account for current flood projections from streams and rivers; 19 weren’t designed for their expected maximum storm surge; 19 face three or more threats that they weren’t designed to handle.

The industry argues that rather than redesign facilities to address increased flood risk, which Jaczko advocates, it’s enough to focus mainly on storing emergency generators, pumps, and other equipment in on-site concrete bunkers, a system they call Flex, for Flexible Mitigation Capability. Not only did the NRC agree with that view, it ruled on Jan. 24 that nuclear plants wouldn’t have to update that equipment to deal with new, higher levels of expected flooding. It also eliminated a requirement that plants run Flex drills.

The commission’s three members appointed by President Trump wrote that existing regulations were sufficient to protect the country’s nuclear reactors. Jaczko disagrees as do the two Democratic appointees. “The majority of the commission has decided that licensees can ignore these reevaluated hazards,” commissioner Jeff Baran wrote in dissent. His colleague Stephen Burns called the decision “baffling.” Through a spokesman, the Republican appointees declined to comment.

“Nuclear power is weird—it exists to produce electricity, and at the same time it can’t exist without electricity,” says Allison Macfarlane, who chaired the NRC from 2012 through 2014. Plants need constant power to pump cool water into a reactor’s core; if flooding interrupts that power supply for long enough, as happened in Fukushima, the core can overheat, melting through its container and releasing deadly levels of radiation.

The true risk to U.S. nuclear facilities may be even greater than what the documents from the nuclear commission show. The commission allowed nuclear plant operators not only to perform their own estimates of current flood risk but also to decide what assumptions to make—for example, the maximum likely hurricane speed or how much rain would fall in an extreme storm. (The commission reviews that work.) The commission also rejected a recommendation by their own staff that would require nuclear power plants to update their risk assessments periodically to reflect the advancing threat of climate change.

Whatever the likelihood of a Fukushima-style disaster, the aftermath offers a glimpse of the costs of failure. Eight years later, much of the adjacent city of Okuma remains uninhabitable; in 2016 the Japanese government estimated total cleanup and compensation costs would approach $200 billion.