The Saudi regime has insisted that its primary motivation for building a nuclear program is to develop a sustainable power source for the country’s desalination plants. A 2009 royal decree outlining Saudi Arabia’s energy policy illustrated the logic: “The development of atomic energy is essential to meet the kingdom’s growing requirements for energy to generate electricity, produce desalinated water, and reduce reliance on depleting hydrocarbon resources.” On the surface, this makes sense. The Saudis need water; for water, they need energy. And they have enough capital—political and economic—to make it happen.

Saudi Arabia is a desert country with no permanent rivers or lakes and erratic rainfall. The vast majority of its territory—95 percent—is covered by one of three deserts: the Rub al-Khali, an-Nafud, or ad-Dahna. Most of Saudi Arabia’s natural reservoirs, such as the Saq-Ram and Wajid aquifer systems, are nearly tapped out. Although other promising reservoirs have been found—for example, the Wasia aquifer, which is thought to hold as much water as the entire Persian Gulf—they are nestled deep in the desert, away from urban areas. Tapping into their full potential would take many years and billions of dollars. Accordingly, the Kingdom has turned to an obvious solution: desalinated water from the Red Sea and the Persian Gulf. According to the latest estimates, the country consumes an estimated 3.3 million cubed meters of desalinated water per day, and desalination provides 70 percent of urban water supplies.

Taking salt out of water is an energy-intensive process. It uses about 15,000 kilowatt-hours of power for every million gallons of fresh water produced. As the world’s second-largest oil producer, Saudi Arabia can afford the energy outlay. It already burns approximately 1.5 million barrels of crude oil equivalent every day, with a significant portion of that output powering desalination plants. But oil-powered desalinization plants are not sustainable. Oil reserves will dry up eventually; Saudi Arabia’s thirst will continue.

A worker stands at a desalination plant, 35 km south of Riyadh, May 4, 2011. Fahad Shadeed / Reuters And so Riyadh has pushed forward with other plans. Over the next few decades, the Kingdom will invest more than $55 billion in desalination projects. By 2032, it will invest over $109 billion in meeting as much as one-third of its energy demand with alternative sources. Nuclear power is a cornerstone of these plans. It is a source that, although costly, can provide large amounts of power nearly indefinitely. The average nuclear power plant (NPP) is designed to have a lifespan of 40 years, whereas traditional thermal power plants—which are the only other platform that can compete with NPPs on cost dynamics—are designed to have a lifespan of 20–25 years. The Kingdom recently signed a $2 billion deal with South Korea to investigate the joint construction of two nuclear reactors over the next 20 years. In total, Saudi Arabia plans to build 16 reactors by 2032. By 2040, it hopes to have added 17 gigawatts of energy capacity—enough to provide 15 percent of the country’s power requirement.

Nevertheless, the Saudis have a major problem to overcome if they want to develop nuclear energy successfully. Light water reactors, which Saudi Arabia is planning to build, use fresh water as a coolant. If the reactor core is not kept cool enough, it melts down, Chernobyl-style. The amount of water different types of NPPs need varies, but they can withdraw as much as 60,000 gallons per megawatt hour, or one billion gallons per day. The amount that is consumed (that is, evaporated) is much smaller, around 600–800 gallons per megawatt-hour, but the reactors still require an enormous available water supply. Since nuclear desalination plants typically only put ten percent of their energy output toward desalination, and since desalination is an energy-intensive process, the inefficiencies at work are apparent. A rough estimate indicates that an NPP would consume one gallon of water for every ten it could create, but the plant would have to withdraw fresh or recycled water on a nearly 1:1 scale.

Light water is technical jargon for ordinary H 2 O, the kind we drink, and the reason reactors use it is that it leaves no residue. Saltwater, on the other hand, isn’t a viable coolant. If it was left to boil away inside a reactor, it would leave behind mountains of salt that would be impossible to shovel out. Moreover, the salt would crust over the uranium fuel rods, insulating them and causing them to overheat.

A hunter sprays water on his falcon to cool it off in a desert area near the Saudi city of Dheba, September 4, 2013. Mohamed Al Hwaity / Reuters Cooling failure is the surest path to nuclear disaster. At Chernobyl, the failure of control rods resulted in an unmoderated reaction that generated excessive heat, leading to a massive steam buildup that eventually burst open the containment chamber like an exploding pressure cooker. In Fukushima, a tsunami flooded cooling water pumps, disrupting coolant flow into the reactors. The pump failures, combined with a prolonged power outage, forced the Japanese power utility TEPCO to use seawater as a temporary coolant. After only two weeks, about 100,000 pounds of salt had accumulated in the reactors.

Saudi Arabia seems unconcerned. Some of the designs that competed for the Saudi contract, such as Babcock and Wilcox’s mPower reactors, suggested the use of alternative coolantslike water or air. Cooling with air does result in about a ten percent loss of efficiency, but in the Saudi case, that would not have mattered much, considering the sheer size of the proposed program and the significance of the difficulties in supplying water.

Similarly, the Saudis could have explored a high-temperature gas reactor (HTGR) such as AREVA’s Antares, which the United States chose for its Next Generation Power Plant project and expects to deploy in 2021. The reactor uses radioactively and chemically inert helium gas, rather than water, as its coolant. And unlike water-based reactors, which have no back-up cooling mechanism, HTGRs have design features that allow them to cool down automatically, even if their primary cooling system fails in an accident. Their use of ceramic-coated fuel pellets creates an effect known as “negative temperature coefficient,” which automatically suppresses the nuclear reaction. Moreover, because of the same effect, HTGRs heat up much slower than other reactors, allowing operators more time for emergency responses if needed. Finally, HTGRs have control rods placed on top of the reactor, which are automatically dropped into place in case of a cooling failure, a process that requires no operator input.

A man with mask smokes a cigarette as he carries a water container in Jeddah, May 29, 2014. Mohamed Alhwaity / REuters In HTGR designs, moreover, the reactor vessel and the steam generator vessel are separate from each other. Cool helium gas enters the reactor vessel, absorbs the reactor’s heat, and is then carried into steam generators, where the resulting steam can be used for electricity production or large-scale industrial applications. Hence, HTGRs are particularly efficient for desalination projects, as the design explicitly allows for the repurposing of steam generators for thermal desalination. For a country seeking to simultaneously address power and water challenges, such a design has incomparable advantages—which the Saudis passed up.

Instead, the Saudis preferred a pressurized water reactor design, specifically South Korea’s System-Integrated Modular Advanced Reactor (SMART). These reactors’ technical capabilities don’t quite match up to those of other designs, such as mPower or Antares. SMART is also an untested design, with no initial demonstration unit and no buyers besides the Saudis. In comparison, the Antares design has already been adopted in the United States, Japan, and Kazakhstan. All these drawbacks, along with the obvious one of SMART’s water-based coolant system, make the Saudis’ choice of the South Korean reactor questionable.

For now, Saudi reactors will have to source the water for their NPPs from desalination plants, meaning that the reactors will most likely be situated close to the coastline. Yet both the Red Sea coast and the Gulf coast are seismically unstable, raising the risk of a seismic event that could result in a cooling failure—as happened in Fukushima. Although there are spaces inland without seismic activity, there’s no water there. The only option would be to pump water inland, but it would have to travel over 30 miles to reach viable inland sites, with each mile of costly pipeline posing an additional risk of breaks or sabotage. A last suggestion has been to use treated wastewater as the coolant for the reactor, but this process would consume a substantial amount of the reactors’ power generation, and wastewater resources as scarce. Moreover, this is a significant technical challenge—currently, there’s only one nuclear plant that uses wastewater as its sole coolant, and it’s unclear that the SMART design would be compatible with the process.

Admittedly, it is difficult to explain why Riyadh has remained heedless to the country’s water challenges. One possibility is that the government was irrationally profligate, not bothering to run the numbers. After all, it is awash in petrodollars and willing to pay any premium for the nuclear option most to its liking. Another possibility, however, is that the motives for developing nuclear energy go beyond desalination. This is not to say that Saudi Arabia does not have legitimate reasons to seek nuclear power—it does. But if the government was also seeking to keep open the possibility of using the country’s nuclear infrastructure to becoming a nuclear power, opting for a more traditional design that has been tested and proven as a viable means for that purpose would be sensible. Either way, Riyadh has done a disservice to its stated goal of creating more fresh water for all.