Special Report: Fukushima and the Future of Nuclear Power

Editor's Note: This is part of IEEE Spectrum's ongoing coverage of Japan's earthquake and nuclear emergency. John Boyd is an IEEE Spectrum contributor reporting from Kawasaki, Japan.

Day six of Japan's nuclear emergency brought few signs of relief to the troubled nation. People woke up Wednesday morning to the news that there had just been a second fire in the No. 4 reactor building of the Fukushima Dai-1 nuclear power plant, which was damaged by the earthquake and tsunami that struck northeastern Japan on March 11.

But this was only one of a series of events that occurred throughout the day. A billow of steam raised fears that two of the structures that contain radioactive materials inside the reactor buildings may have been damaged. And fluctuating radiation levels at the nuclear plant made it difficult for workers to combat the problems.

Fresh Flames

The new fire was discovered by a Tokyo Electric Power Company (TEPCO) worker at 5:45 a.m. local time. The blaze broke out in the same location where a fire occurred yesterday: the storage pool where spent fuel from the No. 4 reactor is kept. TEPCO reported that no flames could be seen thirty minutes after the fire was initially sighted.

The No. 4 reactor was shut down at the time of the earthquake for inspection and maintenance. The fires at the No. 4 building have raised fears that similar incidents could occur at the No. 5 and No. 6 reactor buildings, which were also shut down for maintenance when the earthquake struck.

No one has been able to say with certainty what caused yesterday's fire in the No. 4 building, or the new fire today. TV footage of the damage caused yesterday showed two huge holes in the walls of the reactor building, as well as substantial damage to the roof.

Some experts surmise that the water level in the storage pool dropped after circulation failed due to the string of aftershocks that have followed the main earthquake. With circulation in the storage pool halted, the radioactivity in the spent fuel would have raised the temperature of the water. This would have caused water to evaporate, eventually exposing the spent fuel rods to the air.

Masashi Goto, a former Toshiba Corporation design engineer of nuclear containment vessels of the kind used in the Dai-1 Plant, said another possibility was "sloshing": the water may have sloshed out of the storage pool due to the earthquake's shaking. Goto said this kind of splashing happened in 2007: "This is what happened during the Kashiwazaki (Nuclear) Plant accident after the earthquake struck it and sloshed water outside the pool."

Goto noted that spent fuel rods continue to generate heat long after they are taken out of operation; that's why they must be submerged in a storage pool container filled with water that is constantly circulated to maintain a safe temperature. NHK, the Japan national broadcaster, reported that 783 fuel rods are held in the No. 4 building's storage pool.

Regardless of whether water circulation stopped or water sloshed out, the exposure of the spent fuel likely started the fire. As the exposed fuel rods heated up, their zirconium casings may have partially melted, causing a chemical reaction between the zirconium and the water or steam. The reaction may have produced volatile hydrogen gas, which may have been sparked to produce a blast.

But Kazuaki Matsui, executive managing director of the Institute of Applied Energy, an independent research organization in Tokyo, told Spectrum that a hydrogen blast would not cause a fire. "Hydrogen burns without flames, so it seems some kind of burnable materials were around, possible brought into the room when maintenance was being conducted," he surmised. The New York Times offered a possible explanation today, reporting that the actual substance burning in the building was lubricating oil from machinery near the storage pool.

To add to the problem, TEPCO informed the government that water temperatures in the spent fuel storage pools in the No. 5 and No. 6 reactor buildings "were higher than normal." In a Wednesday press conference, Chief Cabinet Secretary Yukio Edano said TEPCO had made preparations to deal with the situation.

Matsui told Spectrum that since the No. 5 and No. 6 reactors were shut down for maintenance before the earthquake, he didn't think "there was anything to worry about as long as the situation is monitored."

A Cloud Rises

Meanwhile, white steam was reported billowing out of the No. 3 reactor building earlier in the morning. The No. 3 reactor building was damaged in an explosion on Monday.

An NHK helicopter positioned 30 kilometers from the plant filmed the emissions that continued to rise from the plant at 10:15 a.m., local time. Edano told reporters during his press conference that the emissions appeared to be steam leaking from the No. 3 reactor's containment vessel, which probably accounted for the rise in radiation levels recorded at 10:45 a.m. Edano said workers trying to inject water into the No. 3 reactor system had to evacuate temporarily, but they returned to the plant after one hour when radiation levels fell.

"We don't know for sure what is causing the steam," says nuclear expert Matsui. "But it seems the earlier hydrogen explosion has damaged a valve or something like that [controlling the] container vessel."

The primary containment vessel is a solid structure of steel and concrete that surrounds the pressure vessel, where the actual nuclear reactions that produce power take place. If the containment vessel in the No. 3 reactor was damaged by Monday's explosion, it increases the possibility that radioactive material will escape the reactor and contaminate the site.

But to add to the confusion, the Nuclear and Industrial Safety Agency said it had measured high radiation levels near the No. 2 reactor. As of now, the source of the leaking radiation is not clear. The No. 2 reactor has caused considerable worry, as a blast on Tuesday at that reactor's building seems to have occurred inside the containment vessel. Officials said Tuesday that the No. 2 containment vessel may be cracked.

TEPCO informed the government on Wednesday that it was having trouble injecting water into the No. 3 reactor because radiations levels had risen to 300 to 400 millisieverts per hour in the vicinity, making it dangerous for the plant workers to stay on site. The company was considering several options to cope with the situation, including calling in a Self Defense Force helicopter to dump water over the No. 3 reactor building (its roof was blown off in Monday's explosion); calling in fire fighters to spray water over the building; and have a ground crew ready to inject water once radiation levels became low enough.

Around 4 p.m. local time a Self Defense Force Boeing CH-47 Chinook helicopter flew over the stricken plant to monitor the radiation and gauge the possibility of a water dump. But the helicopter operation was later aborted. Broadcaster NHK reported that radiation levels above the plant were too high to allow Self-Defense Force personnel to safely carry out the mission. In a 6 p.m. press conference Chief Cabinet Secretary Edano said a TEPCO ground crew was making preparations to deal with the problem reactor from the ground. NHK announced around 7 p.m that a ground crew had moved in with a mobile pump and had begun spraying water over the reactor area.

The Public Worries

While all this was going on a 6.0 magnitude earthquake struck just off the coast of Chiba Prefecture around 1 p.m. local time on Wednesday, rattling nearby Tokyo. The Japan Metrological Agency gave no tsunami warning, but the earthquake has put many Japanese in the capital on edge. Tokyo residents are already dealing with rolling power black-outs, bare shelves in supermarkets due to panic buying, and limited train services. International schools are closed because worried families are taking their children out of country, and a growing number of both foreigners and Japanese are also escaping abroad.

In an attempt to raise the spirits of the people, Emperor Akihito gave a televised address to the nation urging the country to unite, and letting the Japanese people know that he was praying for the nation.

The Institute of Applied Energy's Kazuaki Matsui says even as the crisis continues to unfold, he has begun to look ahead to the future of the nuclear industry in Japan. "TEPCO planned to add two larger 1.36 gigawatt reactors to the site, but this has been postponed," he said. "To say I'm worried about the future of the industry is being optimistic."

Image: DigitalGlobe/Getty Images

The Conversation (0)
This photograph shows a car with the words “We Drive Solar” on the door, connected to a charging station. A windmill can be seen in the background.

The Dutch city of Utrecht is embracing vehicle-to-grid technology, an example of which is shown here—an EV connected to a bidirectional charger. The historic Rijn en Zon windmill provides a fitting background for this scene.

We Drive Solar

Hundreds of charging stations for electric vehicles dot Utrecht’s urban landscape in the Netherlands like little electric mushrooms. Unlike those you may have grown accustomed to seeing, many of these stations don’t just charge electric cars—they can also send power from vehicle batteries to the local utility grid for use by homes and businesses.

Debates over the feasibility and value of such vehicle-to-grid technology go back decades. Those arguments are not yet settled. But big automakers like Volkswagen, Nissan, and Hyundai have moved to produce the kinds of cars that can use such bidirectional chargers—alongside similar vehicle-to-home technology, whereby your car can power your house, say, during a blackout, as promoted by Ford with its new F-150 Lightning. Given the rapid uptake of electric vehicles, many people are thinking hard about how to make the best use of all that rolling battery power.

The number of charging stations in Utrecht has risen sharply over the past decade.

“People are buying more and more electric cars,” says Eerenberg, the alderman. City officials noticed a surge in such purchases in recent years, only to hear complaints from Utrechters that they then had to go through a long application process to have a charger installed where they could use it. Eerenberg, a computer scientist by training, is still working to unwind these knots. He realizes that the city has to go faster if it is to meet the Dutch government’s mandate for all new cars to be zero-emission in eight years.

The amount of energy being used to charge EVs in Utrecht has skyrocketed in recent years.

Although similar mandates to put more zero-emission vehicles on the road in New York and California failed in the past, the pressure for vehicle electrification is higher now. And Utrecht city officials want to get ahead of demand for greener transportation solutions. This is a city that just built a central underground parking garage for 12,500 bicycles and spent years digging up a freeway that ran through the center of town, replacing it with a canal in the name of clean air and healthy urban living.

A driving force in shaping these changes is Matthijs Kok, the city’s energy-transition manager. He took me on a tour—by bicycle, naturally—of Utrecht’s new green infrastructure, pointing to some recent additions, like a stationary battery designed to store solar energy from the many panels slated for installation at a local public housing development.

This map of Utrecht shows the city’s EV-charging infrastructure. Orange dots are the locations of existing charging stations; red dots denote charging stations under development. Green dots are possible sites for future charging stations.

“This is why we all do it,” Kok says, stepping away from his propped-up bike and pointing to a brick shed that houses a 400-kilowatt transformer. These transformers are the final link in the chain that runs from the power-generating plant to high-tension wires to medium-voltage substations to low-voltage transformers to people’s kitchens.

There are thousands of these transformers in a typical city. But if too many electric cars in one area need charging, transformers like this can easily become overloaded. Bidirectional charging promises to ease such problems.

Kok works with others in city government to compile data and create maps, dividing the city into neighborhoods. Each one is annotated with data on population, types of households, vehicles, and other data. Together with a contracted data-science group, and with input from ordinary citizens, they developed a policy-driven algorithm to help pick the best locations for new charging stations. The city also included incentives for deploying bidirectional chargers in its 10-year contracts with vehicle charge-station operators. So, in these chargers went.

Experts expect bidirectional charging to work particularly well for vehicles that are part of a fleet whose movements are predictable. In such cases, an operator can readily program when to charge and discharge a car’s battery.

We Drive Solar earns credit by sending battery power from its fleet to the local grid during times of peak demand and charges the cars’ batteries back up during off-peak hours. If it does that well, drivers don’t lose any range they might need when they pick up their cars. And these daily energy trades help to keep prices down for subscribers.

Encouraging car-sharing schemes like We Drive Solar appeals to Utrecht officials because of the struggle with parking—a chronic ailment common to most growing cities. A huge construction site near the Utrecht city center will soon add 10,000 new apartments. Additional housing is welcome, but 10,000 additional cars would not be. Planners want the ratio to be more like one car for every 10 households—and the amount of dedicated public parking in the new neighborhoods will reflect that goal.

This photograph shows four parked vehicles, each with the words \u201cWe Drive Solar\u201d prominently displayed, and each plugged into a charge point.Some of the cars available from We Drive Solar, including these Hyundai Ioniq 5s, are capable of bidirectional charging.We Drive Solar

Projections for the large-scale electrification of transportation in Europe are daunting. According to a Eurelectric/Deloitte report, there could be 50 million to 70 million electric vehicles in Europe by 2030, requiring several million new charging points, bidirectional or otherwise. Power-distribution grids will need hundreds of billions of euros in investment to support these new stations.

The morning before Eerenberg sat down with me at city hall to explain Utrecht’s charge-station planning algorithm, war broke out in Ukraine. Energy prices now strain many households to the breaking point. Gasoline has reached $6 a gallon (if not more) in some places in the United States. In Germany in mid-June, the driver of a modest VW Golf had to pay about €100 (more than $100) to fill the tank. In the U.K., utility bills shot up on average by more than 50 percent on the first of April.

The war upended energy policies across the European continent and around the world, focusing people’s attention on energy independence and security, and reinforcing policies already in motion, such as the creation of emission-free zones in city centers and the replacement of conventional cars with electric ones. How best to bring about the needed changes is often unclear, but modeling can help.

Nico Brinkel, who is working on his doctorate in Wilfried van Sark’s photovoltaics-integration lab at Utrecht University, focuses his models at the local level. In his calculations, he figures that, in and around Utrecht, low-voltage grid reinforcements cost about €17,000 per transformer and about €100,000 per kilometer of replacement cable. “If we are moving to a fully electrical system, if we’re adding a lot of wind energy, a lot of solar, a lot of heat pumps, a lot of electric vehicles…,” his voice trails off. “Our grid was not designed for this.”

But the electrical infrastructure will have to keep up. One of Brinkel’s studies suggests that if a good fraction of the EV chargers are bidirectional, such costs could be spread out in a more manageable way. “Ideally, I think it would be best if all of the new chargers were bidirectional,” he says. “The extra costs are not that high.”

Berg doesn’t need convincing. He has been thinking about what bidirectional charging offers the whole of the Netherlands. He figures that 1.5 million EVs with bidirectional capabilities—in a country of 8 million cars—would balance the national grid. “You could do anything with renewable energy then,” he says.

Seeing that his country is starting with just hundreds of cars capable of bidirectional charging, 1.5 million is a big number. But one day, the Dutch might actually get there.

This article appears in the August 2022 print issue as “A Road Test for Vehicle-to-Grid Tech.”

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