POURING SEAWATER ON THE REACTORS AT FUKUSHIMA NUCLEAR POWER PLANT
Spraying Water on a reactor As a kind of last resort, with the main cooling apparatus at the Fukushima nuclear power plant not working, TEPCO workers flooded the reactors affected by the tsunami with seawater to cool them down. The move produced radioactive steam but staved off a much bigger problem: a full meltdown of the nuclear cores in reactors. [Source: New York Times, March 14, 2011]
Evan Osnos wrote in The New Yorker: “In a log later filed with the International Atomic Energy Agency, workers recorded frantic efforts to get water on the fuel. They tried to use a fire truck, but waves had thrown a storage tank across the road, making it impassable. To restore electricity, they called for emergency power vehicles, but those were stymied by traffic on damaged roads. In the dark, even familiar parts of the plant became perilous, because the tsunami had blown out the manhole covers. [Source: Evan Osnos, The New Yorker, October 17, 2011]
The International Atomic Energy Agency said that ''as a countermeasure to limit damage to the reactor core,'' Tokyo Electric proposed injecting seawater mixed with boron -- which can choke off a nuclear reaction -- and it began to do that at 10:20 p.m. Saturday. It was a desperation move: The corrosive seawater effectively disabled the 40-year-old plant; the decision to flood the core amounted to a decision to abandon the facility.
The New York Times reported, “But even that operation has not been easy. To pump in the water, the Japanese have apparently tried used firefighting equipment -- hardly the usual procedure. But forcing the seawater inside the containment vessel has been difficult because the pressure in the vessel has become so great. One American official likened the process to 'trying to pour water into an inflated balloon,' and said that on Sunday it was 'not clear how much water they are getting in, or whether they are covering the cores.' The problem was compounded because gauges in the reactor seemed to have been damaged in the earthquake or tsunami, making it impossible to know just how much water is in the core...Workers at the pumping operation are presumed to have been exposed to radiation; several workers, according to Japanese reports, have been treated for radiation poisoning. It is not clear how severe their exposure was.”
Christopher D. Wilson, a reactor operator and later a manager at Exelon's Oyster Creek plant, a plant similar to the one in Fukushima, told the New York Times, ''normally you would just re-establish electricity supply, from the on-site diesel generator or a portable one.'' Portable generators have been brought into Fukushima, he said. The problem, he said, was that the hookup is done through electric switching equipment that is in a basement room flooded by the tsunami. ''Even though you have generators on site, you have to get the water out of the basement,'' he said.
Vent and Bleed at the Fukushima Nuclear Power Plant
One of the first emergency measures taken to try to bring the reactor under control after the tsunami was the opening of pressure-release vents at the reactor. Pressure in the No. 1 reactor's containment vessel shot up to a level nearly double its designed strength. Given the situation, TEPCO came to the conclusion that venting radioactive steam from the reactor was needed to prevent an explosion. Such a measure had never before been taken in this country. Opening the vent is meant to release pressure that builds up inside the reactor after the core cooling systems are knocked out. This, in turn, is meant to prevent the reactor core from being damaged and make it easier to inject cooling water into the reactor — and avoid a meltdown. This was supposed to have been done at the Fukushima plant immediately after power was lost after the tsunami , but the vent was opened too late. The procedure began only after the meltdown started.
Eric Talmadge and Mari Yamaguchi of AP wrote: “Fukushima Dai-ichi's operators, meanwhile, were faced with a twofold response: Vent and flood. Venting to release pressure and prevent an explosion, flooding to keep things cool. But venting would release radioactivity into the air. And flooding with seawater would ruin the equipment because of the salt.” [Source: Eric Talmadge and Mari Yamaguchi, Associated Press, July 2, 2011]
“Around 9 p.m., less than six hours after the tsunami, officials at the prime minister's office started to press TEPCO to vent. TEPCO hesitated. Fukushima Dai-ichi was the utility's golden goose. Designed primarily by General Electric, it went online in 1971 and had kept the lights shining in Tokyo ever since. Unlike newer facilities, it was paid for, and it was generating profits with each megawatt it produced. TEPCO knew that venting radioactivity would cast doubt on the safety of the nuclear industry around the nation, and the world. Government officials have alleged that the company didn’t want to release radiation, because it would have immediately invited comparisons to the Chernobyl disaster, in the U.S.S.R., in 1986. But the options were dwindling.”
“The outage of primary and backup power — a scenario that exceeded planners' precautions — was severely hampering operations. The first emergency power vehicle sent by TEPCO got stuck in the chaotic post-tsunami traffic. A backup truck from another power company arrived at 11 p.m., but the cable it brought was too short to hook up.”
“At 3:05 a.m., Trade and Industry Minister Banri Kaieda trotted out TEPCO executive Akio Komori for a public announcement of the plan to vent the Unit 1 containment vessel. Seven minutes later, Edano took to the podium, this time to warn the public that the action would entail the release of radioactive isotopes. Again, he urged calm.”
“For those who knew what was happening, the urgency was mounting. The containment chamber around the core was bulging with pressure twice as high as its maximum operational limit and nearly matching the company's required venting standard. "We kept telling TEPCO to do it quickly, asking how come it wasn't happening," Edano recalled later. Nearly four hours after the initial announcement, an exasperated Kaieda ordered TEPCO to vent. It was 6:50 a.m.”
Prime Minister Naoto Kan Visits the Fukushima Nuclear Power Plant
Kan checking out tsunami damage Finally, Prime Minister Kan flew by helicopter to the plant and demanded that Tokyo Electric open the vent. The Yomiuri Shimbun reported: ‘shortly after 1 a.m. on March 12--about 10 hours after the massive earthquake and tsunami struck--Prime Minister Naoto Kan was becoming increasingly exasperated. Kan told his aides at the Prime Minister's Office that he wanted to go and visit the Fukushima No. 1 nuclear power plant to grasp the situation in person. But Chief Cabinet Secretary Yukio Edano, 47, tried to dissuade him from doing so, saying, "If you leave the Prime Minister's Office at this moment, you'll come under fierce criticism." Kan shouted in anger. "You idiot! Which is more important, ending this situation or thinking about the risk of drawing fire?" [Source: Yomiuri Shimbun, June 9, 2011]
At 6:14 a.m. Kan headed for the plant in a Self-Defense Forces helicopter and arrived there at 7:11 a.m. Eric Talmadge and Mari Yamaguchi of AP wrote: “Like everyone else in the entourage, Kan wore a blue-gray work uniform and had a dosimeter hanging around his neck. His aide, Shimomura, a former TV journalist, was assigned to chronicle the event. He started filming as the group boarded a minibus bound for the emergency crisis headquarters.” [Source: Eric Talmadge and Mari Yamaguchi, Associated Press, July 2, 2011]
“It looked normal enough from the outside. Inside, though, was a madhouse. Dozens of workers raced back and forth, trying not to step on about 20 others either slumped to the floor or sleeping in blankets in the hallway. Shimomura turned off the camera. This scene would not reassure the nation, or the world. Escorted by TEPCO officials, Kan strode past men so preoccupied or tired that they didn't even acknowledge the presence of their country's leader.”
“Kan, known for his short temper, fired questions at plant executives and pointed at diagrams of the reactors on a sheet of paper in front of them. He yelled at TEPCO Vice President Sakae Muto and plant chief Masao Yoshida, his onsite escorts, demanding to know why the venting and seawater injection were not happening.” "Has the venting been done yet?" he shouted, according to a Yomiuri Shimbun article, in a meeting room in a strongly earthquake-resistant building used as a base for the restoration work. At that moment, more than five hours had passed since the government had told TEPCO to vent steam from the reactor. Kan regained his composure as Yoshida told him, "We'll form a suicide squad to do it."
The discussions lasted only half an hour. At 8 a.m., Kan was on his way back to Tokyo.” By then, TEPCO would later acknowledge, the core at Unit 1 had mostly melted, and units 2 and 3 were not far behind.
Workers Tried Frantically to Open Vents at the Fukushima Nuclear Power Plant
Surging radiation forced workers to abort their attempt to open the valves manually. Then they tried to open them remotely and repeatedly failed, probably because of the power outage but possibly also a design flaw. The equipment had never been used in a real-world crisis. Unit 1 was a ticking time bomb.
The Yomiuri Shimbun reported: “Workers at the Fukushima No. 1 nuclear power plant tried frantically to open the vents of a reactor containment vessel to prevent an explosion in the hours after the March 11 tsunami, but high radiation levels and confusion in the central control room hampered their efforts, according to a report by the plant's operator. According to a TEPCO report — compiled from workers' statements and company records about the response to the crisis between March 11 and 15 — TEPCO asked the government about opening the vents at about 1:30 a.m. on March 12, and the government gave the plan the green light.” [Source: Yomiuri Shimbun, June 20, 2011]
“TEPCO headquarters then contacted the nuclear plant and said: "We want you to use whatever means you have to open the vents. Do it after we make an announcement at 3 a.m."However, work to open the vents quickly became bogged down. According to the report, when workers opened doors in the reactor building to measure radiation inside, a whitish steam poured out and they had to pull back before they could get any readings. At about 4:30 a.m., all on-duty personnel were instructed not to go near the area due to concerns that an aftershock could trigger another tsunami. About 15 minutes later, hand-held dosimeters and full-face masks--equipment essential for doing this work--were finally delivered to the control room.”
Even so, little progress was being made. At 6:50 a.m., the government ordered the vents be opened. However, the TEPCO report contains no mention of work done from 6 a.m. until 8:03 a.m., when plant manager Masao Yoshida ordered the vents be opened just before Prime Minister Naoto Kan--who had arrived at 7:11 a.m. to inspect the plant--left by helicopter.
inside the control room on March 11
Venting Finally Done at the Fukushima Nuclear Power Plant
The Yomiuri Shimbun reported: “As soon as Kan left the crippled power plant after 8 a.m., Yoshida immediately instructed his men to carry out the venting. Work to prepare for the venting at the No. 1 reactor started at 9:15 a.m. Workers headed for the reactor building, carrying nitrogen cylinders and batteries over their shoulders. They called the mission their "last service." In a severe working environment where they were exposed at one point to more than 106 millisieverts of radiation, a level that exceeded the limit permitted for workers at nuclear power plants, three teams of two people took turns venting steam from the reactor. At about 2 p.m., the venting was deemed a success. [Source: Yomiuri Shimbun, June 9, 2011]
“TEPCO has cited slowness in the evacuation of residents in neighboring areas as a reason for its delay in carrying out the venting. But the government-ordered evacuation of people living within three kilometers of the plant was completed by 12:30 a.m. on March 12. It remains unknown why Yoshida waited for hours to order workers to conduct the venting. A photograph provided by TEPCO showed that updates of the situation on the site were given on a whiteboard in the No. 1 reactor's central control room. But from 6:29 a.m., shortly after Kan departed the Prime Minister's Office, to 9:04 a.m., an hour after he left the plant, there was nothing written on the board. Speculation has arisen that work to fight the crisis was stalled during the missing 2½ hours.” A senior TEPCO official told the Yomiuri Shimbun, director had to accompany the prime minister. I'm not sure if the hydrogen explosion could have been prevented, but I'm sure [Kan's visit] wasted our time."
TEPCO spokesman on nuclear issues Junichi Matsumoto has insisted Kan's visit did not hamper work at the plant. "[The instruction to open the vents and Kan's visit] just happened to overlap," Matsumoto said at a press conference. "Although there aren't any specific records [of work done while Kan was at the plant], our employees were confirming the situation on the ground." [Source: Yomiuri Shimbun, June 20, 2011]
Eric Talmadge and Mari Yamaguchi of AP wrote: “At 2:30 p.m., workers burst into applause. Vapor was rising from the Unit 1 stack and containment vessel pressures fell — confirmation that the venting was working. But within half an hour, they ran out of fresh water. This was what TEPCO had dreaded. Fukushima Dai-ichi was built right next to the biggest source of water on the planet — the Pacific Ocean. Pumping water out of the ocean is an absolute last resort, however. The reactors would never be usable again.” [Source: Eric Talmadge and Mari Yamaguchi, Associated Press, July 2, 2011]
“Yet again, TEPCO officials waffled. At 3:36 p.m., almost 24 hours to the minute after the second tsunami hit, the hydrogen inside Unit 1 combined with oxygen already there and exploded, in a fiery blast that blew off the roof and sent a plume of contaminated smoke and debris into the sky. The decision to use seawater was unavoidable. Blasts at units 2, 3 and 4 would follow in the coming days. TEPCO's primary task, and for months or even years, is still to repair the damage from the explosions.”
inside the control room
Fukushima Venting Team
Evan Osnos wrote in The New Yorker: Of the six reactors, No. 1 needed the most urgent help: the uranium was melting through the fuel rods, and when the damaged rods mixed with steam they gave off hydrogen, which is highly combustible. In order to prevent an explosion, the steam had to be released through a vent, and that meant piping radiation straight into the air. But the alternative was worse: wait too long, and an explosion would release a far larger burst of radiation. [Source: Evan Osnos, The New Yorker, October 17, 2011]
According to Yomiuri Shimbun, the chief of the plant replied, “We’ll form a suicide squad to do it.” Opening the vent was such an unusual prospect that workers needed the blueprints to figure out how to do it, but the prints were in a building whose ceiling had collapsed. Only after they were retrieved did workers learn how the vent could be opened manually. Six workers divided into three teams of two. Going in alone would be impossible, because the men would be operating in darkness, amid aftershocks, without radio contact with headquarters. According to the log, the teams would work in a relay, so that no one would be exposed to too much radiation. [Source: Evan Osnos, The New Yorker, October 17, 2011]
The six workers assembled in the main control room. They had swallowed tablets that flooded their thyroid glands with iodine and hindered their bodies from absorbing radioactive iodine from the air; they wore dosimeters — portable radiation detectors that would warn them when they were nearing the legal limits of exposure. They were outfitted in heavy firefighting suits with oxygen tanks, gear that would shield them from inhaling and absorbing through their skin tiny particles that emit alpha and beta radiation, which can linger in the body for years, causing organ damage. The equipment, however, would provide little protection against gamma rays, so their only true defense would be to get out of danger as fast as possible.
At 9:04 A.M., the first two workers, carrying flashlights, set off into the darkness of Reactor Building No. 1. They found the manual gate valve, which can be opened by laboriously cranking a metal handle through hundreds of revolutions, like a man pumping an old-fashioned handcar down a railroad track. They cranked it open a quarter of the way and retreated. They had been inside for eleven minutes. The second team went in, but, with the vent partly ajar, the radiation level was climbing fast, and the men were driven back before they could even reach their target. They had been inside for no more than six minutes, but one of them received a radiation dose greater than the legal limits allowed for five years of work in the plant. It was deemed too risky to try again, and the third team was disbanded.
TEPCO: Everything Was by the Book When the Cooling of the Reactor was Stopped
The Yomiuri Shimbun reported: “An emergency cooling system for the No. 1 reactor at the Fukushima No. 1 nuclear power plant was shut down manually by plant workers on March 11, after the earthquake but before the tsunami hit the plant, was revealed in a TEPCO report Co. to the Nuclear Safety and Industrial Safety Agency.
TEPCO said the immediate response procedures taken on March 11 were in line with the firm's operational manual. According to the report when the magnitude-9.0 earthquake struck at 2:46 p.m., the Nos. 1-3 reactors lost all external power, but emergency power sources were still in working order. The quake triggered an automatic shutdown of the No. 1 reactor, and control rods were inserted into the reactor core.
At 2:52 p.m., an isolation condenser--a system designed to cool the reactor--was automatically activated. But at 3:03 p.m., just 11 minutes later, the cooling system was suspended manually by plant workers. The TEPCO operational manual says the reactor's temperature should not be allowed to fall at a rate of 55 C per hour or more, and isolation condenser operations should be adjusted to prevent such an occurrence.
TEPCO said its workers halted the cooling system because it had caused excessive cooling, with the reactor temperature falling more than 100 C in the time the condenser had been operating. The workers soon reactivated the condenser, before the tsunami hit the plant shortly after 3:30 p.m. The tsunami wiped out the direct-current power supply to the plant, and the power loss was interpreted by control systems as indicating a pipe fracture.This set off an automatic shutdown of the condenser, closing a series of valves between it and the reactor. Plant workers suspected the valves had been closed, and a visual check confirmed it. The workers then manually opened the valves, enabling the restart of the condenser, according to the report.
Meanwhile, the Nos. 2 and 3 reactors were using a different type of cooling system, known as a reactor core isolation system. The report said losses of external power caused the systems at both reactors to halt several times, and on each occasion TEPCO workers manually restarted the systems, in line with the operation manual. The system at the No. 2 reactor continued to be operated in this fashion until 1:25 p.m. on March 14.
At the No. 3 reactor, the cooling system stopped working at 11:36 a.m. on March 12. About an hour later, another emergency cooling system called a high-pressure core-flooding system was put into use at the No. 3 reactor, but this was stopped at 2:42 a.m. on March 13.The operation was back under way at 9:25 a.m. that day, using freshwater containing boric acid. The relative lack of continuity in efforts to cool the No. 3 reactor is believed to have caused meltdown to occur faster there than that at the No. 2 reactor.
Delays Caused by Absent TEPCO Executives and Worries About Costs
TEPCO's venting of radioactive steam from a reactor at the crippled Fukushima No. 1 nuclear plant came too late to prevent explosions at the plant. There is some evidence that this occurred because TEPCO’s top officials were not at the company headquarters and the Japanese government did more to impede them than the help them. The Yomiuri Shimbun reported, for example, that TEPCO President Masataka Shimizu had managed to get on an Air Self-Defense Force plane near Nagoya but was not given permission by the government to land near Tokyo and had to return to Nagoya, and was not able to get to Tokyo until the next day. Shimizu, according to the newspaper, got permission from the Kan government cabinet to use the plane but no one informed the defense minister and he ordered the plane to return to where it took off.
The Yomiuri Shimbun reported that some think that “the absence of top TEPCO officials from the company early on in the crisis might have adversely affected the company's decision-making process regarding the venting of steam from the reactor. At the time of the earthquake, Chairman Tsunehisa Katsumata was in Beijing, while President Masataka Shimizu was in Kansai, both of them on business trips. Lacking their top two executives, the utility's head office in Tokyo launched a disaster management headquarters with Vice President Takashi Fujimoto as its acting chief.” [Source: Yomiuri Shimbun, April 13, 2011]
“According to sources, Katsumata received a phone call from his secretary at 2:52 p.m. on March 11 — immediately after the earthquake. Katsumata was visiting China as the head of a Japan-China economic exchange group. He reportedly told the secretary he would cancel the rest of his trip and "return to Japan right away." But since Narita Airport was closed due to the quake, Katsumata did not arrive in Japan until March 12. He landed at about 12:50 p.m. but only arrived at the office a little before 4 p.m. due to traffic congestion.”
Shimizu, meanwhile, found out about the earthquake via TEPCO's independent alert system on his mobile phone. Shimizu called Fujimoto and tried to return to Tokyo, but was not able to find a train, plane or helicopter to take him to the capital. He decided to head by train to Nagoya where he hired a helicopter and arrived in Tokyo at about 10 a.m. on March 12.
“The firm's top two executives did not arrive at its Tokyo headquarters until about 20 hours after the earthquake. "There was no problem with the chain of command since we kept in touch by cell phone," according to one TEPCO official. But during that time, the firm faced a series of major decisions. Venting of the reactor did not take place until 10:17 a.m. after Shimizu had arrived at the main office. The decision to inject seawater to cool the reactor cores was another big call, but did not begin until past 8 p.m. on March 12 after Katsumata returned to Japan.”
“Venting a reactor heightens the risk of radioactive contamination. This decision could place enormous social responsibility on the company and also make it liable for substantial damages. And injecting water into a reactor core essentially destroys it. One reactor costs about 100 billion yen to replace. A company's shareholders generally are informed before such major actions are taken, and they are not the type of orders that can easily be conveyed over a mobile phone from the Kansai region or China.”
Pouring Water on the Reactors at Fukushima
Evan Osnos wrote in The New Yorker: By March 15th, the fourth day after the meltdown began, the radiation levels in the main control room of Reactor No. 2 were so high that workers once again had to rotate in and out. It was clear that in the process of bringing the plant under control some people would receive doses previously considered illegal. Normally, Japanese workers were barred from receiving more than a hundred millisieverts over five years; now the Health Ministry officially raised that limit to two hundred and fifty millisieverts — five times the maximum exposure permitted for American workers. “It would be unthinkable to raise it further than that,” the Health Minister, Yoko Komiyama, said at a news conference. [Source: Evan Osnos, The New Yorker, October 17, 2011]
Members of Japan’s defense forces arrived the next day. The results were not reassuring. Chinook helicopters scooped up buckets of seawater from the Pacific and nosed in toward Reactor No. 3, but they were forced back by high radiation. Lead plates were bolted to the bellies of the choppers for a second attempt, the next morning, but most of the water scattered in the wind. By evening, military fire engines had arrived, equipped with steel cladding and high-pressure hoses designed for jet-fuel fires. Water arced into the mangled remains, and steam poured out of Reactor No. 3.
A more decisive maneuver had been gathering strength, with far less attention, for several days. Even as buildings exploded, some of the workers had hooked up a train of fire trucks capable of generating enough pressure to inject water directly into the fuel cores. (As with the helicopters, they drew water from the ocean — a desperate measure, because a multibillion-dollar reactor that has been bathed in saltwater can never be used again.) The drenching continued around the clock, and it went on for months — an approach known as “feed and bleed.” Casto, of the N.R.C., said, “No one ever envisioned steam-cooling reactors for long periods of time. In reactor world, this is all new.” The process was ungainly, and it produced millions of gallons of radioactive water that is dangerous to store, but it probably did more than any other measure to avert a far worse disaster.
Pumping Seawater on the Reactors
spraying purified water Workers used the process of “feed and bleed” — feeding cool water around the reactors’ fuel rods to bleed away excess heat. “Pumping water into nuclear reactors and storage pools for spent fuel rods at the Fukushima No. 1 power plant was an indispensable move. If the reactors were not kept cool and the pools full, an even worse disaster could have occurred at the stricken nuclear facility.”
According to data released by TEPCO on May 16, injection of seawater into the No. 1 reactor began at 7:04 p.m. on March 12. TEPCO decided to use seawater because its freshwater supply was running short. According to the sources, TEPCO informed Kan in advance about the plan to switch from freshwater to seawater. Kan asked Haruki Madarame, chairman of the Cabinet Office's Nuclear Safety Commission whether injecting seawater would pose a risk of re-criticality, and Madarame said it was possible. Therefore at 6 p.m. March 12, Kan instructed the commission and the Nuclear and Industrial Safety Agency of the Economy, Trade and Industry Ministry to examine the possibility that injecting seawater would lead to re-criticality. Later Madarame said he said no such thing, adding “I’m insulted by the claim.” [Source: Yomiuri Shimbun, May 22, 2011]
Because the prime minister expressed concern, TEPCO stopped injecting seawater at 7:25 p.m., about 20 minutes after it had begun. At 7:40 p.m., the commission reported to Kan that injecting seawater would not trigger re-criticality. At 7:55 p.m., Kan ordered Economy, Trade and Industry Minister Banri Kaieda to instruct TEPCO to resume injecting seawater. TEPCO did so at 8:20 p.m. It was originally that injection of seawater was stopped for about 55 minutes but it turned out that plant chief Masao Yoshida disobeyed the order and kept injecting seawater even though he was todl not to. Kan denied claims that he instructed TEPCO to stop injecting seawater into the No. 1 reactor.
Prof. Hisashi Ninokata of Tokyo Institute of Technology, an expert in nuclear reactor engineering, said: "It's certain the nuclear fuel rods inside the No. 1 reactor were damaged. It's highly likely that suspending the injection of seawater made the situation worse." "As it was the second day of the crisis, there was almost no information about conditions inside the reactor, and thus it was necessary to cool the fuel at any cost," Ninokata said. "Even if the seawater caused re-criticality, it wouldn't discharge extremely high levels of energy. If the prime minister was more afraid of re-criticality [than of the nuclear fuel continuing to overheat], he was completely wrong."
Between March 12 — the day after the plant was damaged by a massive earthquake and tsunami — and April 12 about 30,000 tons of water have been sprayed into the reactors by Self-Defense Forces, police and other workers.” [Source: Yomiuri Shimbun, April 2011]
But the action was not without consequences. Water inside the building of the second reactor became so contaminated that a worker would only be able to be exposed to it for no more than fifteen minutes each year. Ironically, the water that was so essential to cool the reactors turned out to be the biggest obstacle to repairing them, a development no one in the government anticipated. TEPCO officials thought they could end the water pouring operations if the cooling system could be repaired. The most important thing, they felt, was cooling the reactor cores. Pouring water on the reactors was therefore only a stopgap measure and they never considered what would happen if the water used became highly radioactive and leaked to other parts of the plant.” [Source: Yomiuri Shimbun, April 2011]
Pools of contaminated water have been found in the Nos. 1, 2 and 4 reactors. The most problematic was water in the No. 2 reactor building that measured more than 1,000 millisieverts per hour. "I can barely stand to look at that figure," Hidehiko Nishiyama, spokesman of the Nuclear and Industrial Safety Agency, said at a news conference.
When TEPCO official Teruaki Kobayashi was asked what would happen to the water being sprayed by fire engines and helicopters he said it would "stay in the reactor building because it's designed to prevent leaks." His colleague Hikaru Kuroda told reporters, "The water being poured into the reactors will evaporate in due course."
Decision to Pump Seawater on the Reactors
Norimitsu Onishi and Martin Fackler wrote in the New York Times, “On the evening of March 12, the Fukushima Daiichi nuclear plant’s oldest reactor had suffered a hydrogen explosion and risked a complete meltdown. Prime Minister Naoto Kan asked aides to weigh the risks of injecting seawater into the reactor to cool it down. At this crucial moment, it became clear that a prime minister who had built his career on suspicion of the collusive ties between Japan’s industry and bureaucracy was acting nearly in the dark. He had received a confusing risk analysis from the chief nuclear regulator, a fervently pro-nuclear academic whom aides said Mr. Kan did not trust. He was also wary of the company that operated the plant, given its history of trying to cover up troubles.” [Source: Norimitsu Onishi and Martin Fackler, New York Times, June 12, 2011]
“Mr. Kan did not know that the plant manager had already begun using seawater. Based on a guess of the mood at the prime minister’s office, the company ordered the plant manager to stop. But the manager did something unthinkable in corporate Japan: he disobeyed the order and secretly continued using seawater, a decision that experts say almost certainly prevented a more serious meltdown and has made him an unlikely hero.”
In testimony in Parliament in late May, Mr. Kan said that he asked advisers to weigh the risks that the seawater injection could cause “recriticality,” a phenomenon in which nuclear fission resumes in melted nuclear fuel lying on the floor of a storage pool or reactor core. Mr. Kan’s aides said they grew worried after Haruki Madarame, the chairman of the Nuclear Safety Commission, a nuclear regulator in the prime minister’s office, warned that the chances of this happening were “not zero.”
On March 12, about 28 hours after the tsunami struck, Tepco executives had ordered workers to start injecting seawater into Reactor No. 1. But 21 minutes later, they ordered the plant’s manager, Masao Yoshida, to suspend the operation. They were relying on an account by the Tepco liaison to the prime minister, who reported back that he seemed to be against it. “Well, he said that was the atmosphere or the mood,” Sakae Muto, Tepco’s executive vice president, explained at a news conference. Atsuyuki Sassa, the former head of the Cabinet Security Affairs Office, said: “Mood? Is this a joke? Making decisions based on mood?”
“But Mr. Yoshida chose to ignore the order,” Onishi and Martin Fackler wrote. “The injections were the only way left to cool the reactor, and halting them would mean possibly causing an even more severe meltdown and release of radiation, experts said. Mr. Yoshida had the authority as the plant manager to make the decision, said Junichi Matsumoto, a senior official at Tepco. And indeed, guidelines from the International Atomic Energy Agency specify that technical decisions should be left to plant managers because a timely response is critical, said Sung Key-yong, a nuclear accident expert who participated in the agency’s recent fact-finding mission to Japan.”
Fukushima Plant Manager Ignores Order by Kan and TEPCO to Halt the Seawater Injection
Prime Minister Naoto Kan was concerned that the seawater injection could cause the reactor to reach recriticality. This led Ichiro Takekuro, a TEPCO executive who was at the Prime Minister's Office, to call Masao Yoshida, head of the plant, and tell him to suspend the injection. TEPCO's head office also urged Yoshida to stop injecting seawater, but he decided it was crucial to continue the measure. [Source: Yomiuri Shimbun, August 16, 2012]
According to a report compiled by the government's Nuclear Incident Investigation and Verification Committee, Yoshida secretly told workers at the plant: "I'll tell you to suspend injecting seawater, but make sure you don't do that." The report states Yoshida then said to suspend the injection in a voice loud enough to be heard by everyone in the office.
According to NAIIC's report, Yoshida said during a hearing that TEPCO's chain of command during the crisis was "disastrous." "It was because Takekuro was at the Prime Minister's Office at the time," the report quoted Yoshida as saying. "If the head office alone had told us to suspend [the sea-water injection], we could have discussed it. "But the Prime Minister's Office--which we didn't think would get involved--made a call to tell us to suspend our activities. 'What the hell is the office talking about?' I thought.”
In a TEPCO teleconference video. Takekuro uses the term "ira-Kan," which combines the first part of the word "irritated" with the prime minister's family name. "Kan gets angry so quickly," Takekuro said in the video. "He scolded me six or seven times. "He yelled: 'On what grounds are you saying this? Can you say everything will be OK no matter what happens?'"
The New Tork Times reported: “After revealing in May that he had ignored the order, Mr. Yoshida explained himself to a television reporter by saying that ‘suspending the seawater could have meant death? for those at the plant. Mr. Yoshida, 56, according to friends, is a square-jawed, hard-drinking and sometimes rough-talking man who is a straight shooter. A practitioner of kendo in his youth, he also quotes from Raymond Chandler and enjoys cooking Italian food. “In class, if a teacher didn’t explain something properly, he’d push for an explanation that satisfied him,” said Masanori Baba, a childhood friend.” “His candor impressed Mr. Kan, who met him the day after the tsunami when he took a trip on a military helicopter to the plant. They shared a willingness to buck the system, as Mr. Kan had when he uncovered the tainted blood scandal. And, in a country where alumni ties are extremely important, they found they had attended the same college, the Tokyo Institute of Technology.”
Pressure Reduction Makes Situation Worse at the No. 2 Fukushima Reactor
At about 4:15 p.m. on March 14, 2011, Yoshida said during a video conference: "Everyone, listen. Also people at [TEPCO] headquarters, please listen. "I just received a phone call from Mr. Madarame, and he suggested we [reduce pressure in the reactor] and inject water instead of venting the containment vessel." While keeping Nuclear Safety Commission Chairman Haruki Madarame, who was at the Prime Minister's Office, on the phone, Yoshida asked a subordinate engineer in charge of safety measures, "Do you think it'll work?" [Source: Yomiuri Shimbun, August 16, 2012]
At the time workers were making preparations to vent the reactor, which was intended to release pressure in the pressure suppression chamber of the containment vessel. Yoshida ordered the action because if pressure in the reactor is reduced before venting, water levels drop rapidly as steam is released from the reactor. Also, if the reactor pressure was not lowered, the injection of water would be impossible. This could lead to serious problems. The engineer explained the venting plan to Madarame. After hanging up the phone, the engineer said, "[Madarame] gave us the go-ahead."
However, just a few minutes later, Yoshida was informed by an on-site worker that the valve for venting was not working even though there was power. "We have to check what's going on," the worker said. TEPCO President Masataka Shimizu was quiet, but suddenly instructed Yoshida, "Please do what Mr. Madarame suggested." He pressed on, saying again, "Do it that way!" Yoshida then said, "I understand." The reactor pressure started decreasing at about 6 p.m. As those on-site feared, water levels dropped rapidly and the fuel rods were completely exposed at 6:22 p.m. The workers failed to conduct the crucial task of injecting water into the reactor because of fire engines being out of fuel and other problems.
The Diet's independent investigation commission on the Fukushima nuclear accident said in its official report that Shimizu's decision to follow Madarame's advice and give instructions contradictory to decisions made by on-site workers made the situation worse. As a result, TEPCO could not inject enough water until late that evening and Yoshida became concerned about a worst-case scenario in which melted fuel could overflow the containment vessel. This possibility caused the company to consider a "withdrawal" of its workers from the plant.
Using Helicopters and Water Canons to Battle the Crisis at the Fukushima Nuclear Plant
On events of March 17, about a week after the earthquake and tsunami, the New York Times reported: “Japanese engineers battled to cool spent fuel rods and restore electric power to pumps at the stricken Fukushima Daiichi Nuclear Power Station as new challenges seemed to accumulate by the hour, with steam billowing from one reactor and damage at another apparently making it difficult to lower temperatures... The Japanese decision to focus their efforts on the No. 3 reactor appeared to suggest that officials believe it is a greater threat, since it is the only one at the site loaded with — mox fuel. [Source: New York Times]
“Authorities reached for ever more desperate and unconventional methods to cool stricken reactors, deploying helicopters and water cannons in a race to prevent perilous overheating, but were hampered by high radiation levels. Japan’s Self-Defense Forces dumped seawater from a helicopter on Reactor No. 3, using a 7.5-ton red bucket suspended several meters below the helicopter. making four passes and dropping a total of about 32,000 liters over it as a plume of white smoke billowed.
Britain’s ITN reported: “Two Ground Self-Defense Force choppers dropped seawater in a 7,500-liter bag four times each in the morning on the No. 3 reactor, an operation about which Defense Minister Toshimi Kitazawa said in Tokyo, “We decided to do this because we thought that today is the time limit.” The 12-minute operation was followed in the evening by the shooting of high-pressure streams of water by six SDF fire trucks. A water cannon truck dispatched by the Metropolitan Police Department also began spraying water, but suspended the work later, the National Police Agency said.” [Source: ITN]
“Kitazawa said that he believes the water from the copters reached the reactor, but plant operator Tokyo Electric Power Co. said that the radiation level remained unchanged at the nuclear plant afterward. .. Concerns are growing that the level of the water filling the spent fuel pool of the No. 4 unit is also becoming low, but Tokyo Electric officials said that the GSDF decided to first spray water on the No. 3 unit, which has vented smoke from Wednesday. The smoke is likely to be steam coming from water boiling in the pool.”
“But a GSDF chopper found earlier in the day that water is left in the pond at the No. 4 unit, according Tokyo Electric. The pools of both the No. 3 and No. 4 units are situated near the roof of the buildings housing the reactors, but are no longer covered with roofs that would reduce any possible radiation leaks since they were blown off by apparent hydrogen blasts.”
Cooling the Reactors at Fukushima Power Plant with Water
recirculation pump About 500 tons of water was poured on to the No.1, No. 2 and No. 3 reactors everyday to keep them from overheating. Radiation at reactor No. 1 peaked at 162 sieverts per hour on March 14. Radiation at reactor No. 2 peaked at 138 sieverts per hour on March 15. These readings were recorded after the reactors loss significant amounts of cooling water, leaving large parts of them exposed to the air. The same happened to reactor No. 3 The injection of water caused radiation levels to drop to between 20 and 31 sieverts, 11 to 22 percent of their peaks, by early April.
Initially seawater was used. One of the problems with the salt is that it corrodes water pipes water pipes, increasing the likelihood of leaks. An effort was made to switch over to fresh water as soon as possible. This was largely achieved by late March with the help of a water-carrying barge provided by the U.S. Navy. Some of the operation involved pumping water into the reactor. It also involved spraying water from fire trucks on containment vessel that hold the reactor.
The emergency cooling process of the fuel in the stricken reactors and spent fuel ponds is a process that may continue for a year or more even after fission has stopped. Japanese reactor operators have little choice but to periodically release radioactive steam and water as they accumulate during the cooling process. Until the damaged cooling apparatus was up and running again TEPCO plant's operator must constantly try to flood the reactors with seawater, then release the resulting radioactive steam and water, to keep the reactor cores from melting down, [Source: David E. Sanger and Matt Wald, New York Times, March 14, 2011]
This suggests that the tens of thousands of people who have been evacuated may not be able to return to their homes for a considerable period, and that shifts in the wind could blow radioactive materials toward Japanese cities rather than out to sea. Re-establishing the normal cooling system first required restoring electric power — which was cut in the earthquake and tsunami — and that took weeks and required plant technicians to work in areas that had become highly contaminated with radioactivity. After that more time was needed to make repairs to pumps and other machines necessary to get the cooling system online.
David E. Sanger and Matt Wald wrote in the New York Times: “The essential problem is the definition of ''off'' in a nuclear reactor. When the nuclear chain reaction is stopped and the reactor shuts down, the fuel is still producing about 6 percent as much heat as it did when it was running, caused by continuing radioactivity, the release of subatomic particles and of gamma rays. Usually when a reactor is first shut down, an electric pump pulls heated water from the vessel to a heat exchanger, and cool water from a river or ocean is brought in to draw off that heat.”
“But at the Japanese reactors, after losing electric power, that system could not be used. Instead the operators are dumping seawater into the vessel and letting it cool the fuel by boiling. But as it boils, pressure rises too high to pump in more water, so they have to vent the vessel to the atmosphere, and feed in more water, a procedure known as ''feed and bleed.'' When the fuel was intact, the steam they were releasing had only modest amounts of radioactive material, in a nontroublesome form. With damaged fuel, that steam is getting dirtier.”
Image Sources: Tepco and YouTube
Text Sources: New York Times, Washington Post, Los Angeles Times, Times of London, Yomiuri Shimbun, Daily Yomiuri, Japan Times, Mainichi Shimbun, The Guardian, National Geographic, The New Yorker, Time, Newsweek, Reuters, AP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.
Last updated January 2013