As destructive as it was, the Japanese Fukushima nuclear disaster five years ago could have been far worse, according to a leading U.S. nuclear safety expert.
The expert, Allison Macfarlane, is past head of the U.S. Nuclear Regulatory Commission. She spoke last week at Livermore’s Bankhead Theater, describing lessons learned from Fukushima. Her talk was part of the Rae Dorough Speaker Series.
As she described it, the disaster began on the afternoon of March 11, 2011, when a great earthquake 43 miles off the Japanese shore lifted the ocean bottom and generated a huge tsunami that destroyed coastal communities some 50 minutes later.
The tsunami killed nearly 16,000 coastal residents outright. The nuclear catastrophe that followed led to the displacement of 160,000 more. Homes, schools and businesses were abandoned.
The central lesson from the experience was that nations that use nuclear energy need to have an independent regulatory body with the authority and resources to intervene and even shut down plants to ensure safety, Macfarlane said.
That was not the case in Japan, where a highly critical study blamed the Fukushima disaster on “collusion” between regulators, the government and the nuclear industry, as well as a Japanese cultural tendency to accept rather than question authority, Macfarlane said.
Macfarlane, a geologist, chaired the Nuclear Regulatory Commission from 2012 through 2014. Today, she heads the Center for International Science and Technology Policy at George Washington University in Washington, D.C.
She has personal ties to Livermore, having been married here in 2001. Her husband, Hugh Gusterson, an anthropologist, has written extensively about Lawrence Livermore National Laboratory and the U.S. nuclear weapons program.
The “ability to question authority” is fundamental to safety in the nuclear industry, Macfarlane said.
As bad as it was, she believes the accident could have been far worse. In the days that followed, the Japanese government was advised that it might have to evacuate Tokyo.
The tsunami, rising as high as 50 feet, easily overtopped 20-foot sea walls built to protect the Fukushima Daiichi nuclear power plant, which with six reactors was one of the world’s largest nuclear energy generators.
The complex was built in the late 1960s and early 1970s, Macfarlane noted, before modern seismic concepts based on plate tectonics were widely understood or adopted.
Four of the six reactors were built at or near sea level, with vital electrical equipment in basements that intersected the water table and required constant pumping.
When the tsunami flooded the basements, diesel generators and batteries were shorted out, cutting off electricity and causing a “station blackout.”
This “nightmare of nuclear engineering” occurs when operators can no longer read the instruments that should tell them what is happening in the plant, she said.
“They probably had a pretty darned good suspicion that things were going pretty badly pretty quickly. Now we know that Unit One, the oldest unit, probably melted down within three or four hours.”
Units Three and Four also melted down. Their buildings, blown apart by hydrogen gas explosions, were clearly visible in Macfarlane’s slides. The belief now is that the explosions were linked. The units were so close together that a build-up of the explosive gas in one could flow into another.
If the site was without electricity, why not bring in other generators, Macfarlane asked rhetorically. The answer was that when things went wrong, they went wrong at several levels.
The entire site was covered with debris from the tsunami and the explosions so it was extremely difficult to clear space to carry out repair work, she said. Radiation levels were high, reducing the time workers could spend at a job.
The tsunami left roads impassable for bringing in more generators. Communications were poor, with land lines down and cell pones operating only intermittently. It was not clear what needed to be done.
“This is what happens with these kinds of accidents,” she said. “They multiply.”
Radioactivity released from the meltdowns first blew out to sea, but when the wind shifted, the countryside to the northwest was contaminated, leaving some areas uninhabitable.
Even today, Macfarlane said, the Japanese are removing huge amounts of contaminated water from the reactor site daily, filtering out all radioisotopes except tritium -- radioactive hydrogen -- before storing it in tanks until the government decides on permanent disposal.
Storage is reaching space limits. The international community has urged the Japanese to dispose of the water at sea, where dilution will reduce contamination to acceptable levels. The fishing industry, however, is strongly opposed to this method of disposal for fear that it would further alienate consumers.
Soil is also contaminated. One of Macfarlane’s slides showed large fields covered with neatly stacked bags of radioactive soil, waiting final disposition. Prior to the reactor meltdowns, she said, these were productive rice paddies.
A frightening near miss
Perhaps as frightening as the disaster that did occur is the one that nearly did.
At the time the tsunimai hit, spent fuel rods from reactor Unit 4 were stored and cooled in a deep pool of circulating water as the reactor underwent routine maintenance. Once the generators were flooded and electricity was shut off, pumps no longer circulated water.
The pool contained 1,535 fuel rods, near its maximum capacity of 1,590. Three days after the accident, the temperature of the water had risen from a normal 80 degrees F. to 183 degrees F. A month later, much of the water had evaporated and the temperature was measured at 194 degrees F.
Analyses suggested that in three more days, the pool would boil dry and the fuel rods could catch fire, Macfarlane said. This would spread so much radioactivity that the site would have to be evacuated.
“The government of Japan was warned” that evacuation could mean loss of whatever control still remained of the meltdowns as well as loss of water in the other storage pools. This in turn could lead to further fires and such a large release of radioactivity that “they’d probably end up evacuating Tokyo,” some 200 miles to the south.
“That all came out after the fact,” she said. Before this new disaster could occur, heroic firemen managed to train hoses on the cooling ponds and fill them with water once again.
In related comments, Macfarlane said:
• “You can’t build a reactor, let it operate and not pay attention to it.” Independent reviewers have to reconsider reactors in light of current scientific thinking. Macfarlane cited the development of tectonic plate theory as an example, since many reactors today were designed and built at a time when the understanding of seismology was primitive compared to today.
• Japan’s nuclear regulations and its regulatory process were considered adequate at the time of the Fukushima disaster. They had been reviewed and approved recently by the International Atomic Energy Agency.
• Countries around the world have learned from the Fukushima disaster, applying lessons to their own nuclear energy needs. “In the nuclear industry, they say an accident anywhere is an accident everywhere.”
Most countries including the U.S. have taken positive steps, like reanalyzing seismic and flood hazards and mandating rapidly available backup and safety equipment that has been tested for compatibility with reactor operations. They have required instrumentation in spent fuel pools to indicate water levels “no matter what.”
• Unlike most countries, the U.S. has chosen not to filter reactor vents through water filters to remove radioactivity. Like the vents in a pressure cooker, these are meant to prevent a far more damaging explosion by releasing pressure in an emergency.
• Several countries – but not the U.S. or Japan -- have taken steps to dispose permanently of the high level radioactive waste that has been removed from reactors and temporarily stored above ground at power plant sites. The clear solution, she said, is deep geologic burial. Finland is closest to operating a burial site, with Sweden and France close behind. Canada is doing a “stellar” job of involving citizens in site selection.
• Providing nuclear power plants to developing countries is unwise if they lack the capacity for strict independent regulation. Russia today is aggressively marketing its reactors abroad, even offering to finance the purchases. Some developing countries are “listening to the siren song of allegedly cheap electricity.” Macfarlane said, "That sounds great, but they had better be sure they build a safe plant!”
• Advanced nuclear energy concepts like the modular molten salt approach advocated by Thorcon, a Florida firm with ties to Livermore, are fine as concepts but “they are paper reactors right now.” They have to be built, then tested, then rebuilt. "You have to deal with the fuel. You’re going to have to get the fuel licensed as well as the reactor design, so go ahead if you can fund it and get this going. I think it will take decades.”