Thursday, Apr 25, 2024

Quake and Tsunami Unleash a Nuclear Crisis in Japan

Japan is still reeling from the greatest disaster it has suffered since the atomic bombing at the nd of World War II. In a deadly one-two punch, a mammoth 9.0 magnitude earthquake was centered on the Pacific ocean floor about 80 miles east of Japan's northeastern coast Friday afternoon, local time. The quake launched a 33-foot high tsunami tidal wave which washed over coastal towns north of Tokyo and swept as far as 6 miles inland. The tsunami devastated a long swath of the Pacific coast of northern Japan, and did major damage to the reactor units at a nuclear generating plant, which now poses a serious radiation exposure threat to the entire region. Japanese officials say it is too soon to estimate the total number killed in the disaster. Whole towns on the northern Pacific coast of Japan's main island, Honshu, were washed away by the tsunami. Tens of thousands are missing and presumed to be dead, with their bodies lying undiscovered under heaps of mud and rubble on land, or swept out to sea by the rampaging tsunami waters. One Japanese news network estimated that the twin disaster has left 430,000 people living in emergency shelters or doubling up with relatives.

It is also too soon to estimate the damage which the disaster will do to Japan’s economy, which is the third largest in the world, after the US and China. Some of the factories destroyed or damaged in northern Japan supplied key components to Japan’s auto makers and electronics manufacturers. The Japanese disasters had an immediate effect on major stock markets around the world, driving prices down out of fears that the broader economic impact will be a drag on world growth and productivity.

 

As massive search and rescue efforts continued Tuesday, the already dangerous situation at the Fukushima Daiichi nuclear plant continued to deteriorate. There were indications that the integrity of the critical steel containment vessel surrounding the plant’s unit 2 nuclear reactor was damaged by an explosion at the bottom of the reactor Tuesday morning. It is also believed that there has been a partial meltdown of the superhot fuel rods in unit 2’s reactor core.

 

FEARS OF ANOTHER CHERNOBYL GROWING

 

The failure of the plant’s cooling system led to a new problem Tuesday, a fire which broke out in the holding pool for spent reactor fuel rods at the 4th reactor unit at the plant, which was not operating when the earthquake and tsunami hit.

 

The compromise of the steel containment vessel of unit 2 and the fire at the holding pool at unit 4, sent radioactive material into the atmosphere. This made the crisis at the Daiichi plant into the second most serious nuclear reactor accident in history.

 

In an address to the Japanese nation Tuesday, Prime Minister Naoto Kan warned that there was “a very high risk” of further radiation leakage from the damaged plant, and pleaded for calm.

 

The government ordered everyone within 20 miles of the plant to stay indoors and shut their windows and vents to prevent outside air from coming in, and banned commercial air traffic in the area. There was also growing public concern throughout Japan about the possibility of exposure to dangerous amounts of radioactive fallout due to shifting wind currents.

 

According to Princeton physics professor Frank von Hippel, the situation at the Daiichi plant is now more dangerous than the partial meltdown in 1979 at the Three Mile Island plant near Harrisburg, Pennsylvania, which was the worst reactor accident ever in the US. Von Hippel fears that a full scale fuel meltdown at Daiichi, followed by a steam explosion, could spread dangerous levels of fallout throughout the region, comparable to the Chernobyl catastrophe in 1986.

 

JAPANPRONE TO EARTHQUAKES

 

Japan has a long history of suffering devastating earthquakes. The quake which triggered the tsunami was the fifth strongest ever measured, and the strongest ever to hit Japan.

 

The Japanese islands, along with other countries on the rim of the Pacific Ocean, is a geologically active area, as indicated by its numerous volcanoes and hot springs. Geologists believe that earthquakes are caused by sudden movements along the intersections of continental and oceanic tectonic plates beneath the earth’s surface. These intersections, where the earthquakes occur, are called faults. A famous example is the San Andreas fault in California, which is responsible for the massive 1906 earthquake which destroyed San Francisco, as well as many more recent California earthquakes.

 

The power or magnitude of earthquakes is not measured on a linear scale. The quake which destroyed San Francisco in 1906 is believed to have had a magnitude of about 8, making it just one-tenth as powerful as the 9.0 magnitude quake which hit Japan last Friday.

 

The tsunami wave hit the Japanese coast with full force within minutes after the earthquake triggered it. Some people on the coast realized the potential danger upon feeling the quake, and immediately sought higher ground, but there was not enough time to get very far.

 

WHAT IS A TSUNAMI?

 

A tsunami, also known as a “seismic sea wave,” is most often caused when an earthquake occurs a relatively short distance beneath the ocean floor, and vertically displaces a large volume of seawater above it. Geologists put the center of Friday’s earthquake just 6 miles below the surface. Seismic waves can also be triggered by landslides or volcanic eruptions.

 

The largest tsunami on record took place on December 26, 2004. It was triggered by a 9.1 magnitude earthquake on the floor of the Indian Ocean, off the west coast of Sumatra in Indonesia. It caused the death of over 230,000 people, mostly in Indonesia, Sri Lanka, India and Thailand. The tsunami inundated coastal communities in Indonesia with waves up to 100 feet high.

 

The tsunami wave spreads out in concentric circles from the point of the earthquake. Coastlines closest to the site of the undersea quake typically get hit first, and the hardest.

 

The wave travels through oceans at a speed of over 400 miles per hour, and can retain much of its power over thousands of miles. The wave’s height when it comes ashore depends a great deal on the exact configuration of the ocean bottom where it reaches land, and the direction in which the wave is traveling.

 

There is no way to accurately predict when and where an earthquake will occur. However, seismologists around the world can pinpoint an earthquake, once it does occur, almost instantaneously, and then issue warnings to areas at risk from a tsunami.

 

TSUNAMI CROSSED THE PACIFIC OCEAN

 

Remnants of the huge tsunami wave which devastated Japan Friday were still as much as 7 feet high when they struck the Hawaiian Islands 4,000 miles away, about 8 hours after the earthquake which triggered it. Smaller waves reached the west coast of the US mainland a few hours later.

 

The leaders of some 50 countries offered to help, but the bulk of the immediate rescue efforts are being carried out by the Japanese themselves.

 

A major worry, in addition to potentially tens of thousands of deaths and the massive physical devastation caused by the earthquake and tsunami, was the crisis at a Japanese nuclear energy plant, where the tsunami knocked out the back-up generators powering the critical cooling systems for three reactors. The failure of the cooling systems has forced the release of radioactive material from the damaged reactors to the atmosphere and three hydrogen explosions. But the greatest danger is the risk of a catastrophic Chernobyl-like disaster if Japanese nuclear engineers cannot find a way to keep the fuel in the reactor cores at the plant from melting down.

 

WHAT IS A NUCLEAR MELTDOWN?

 

Reactor fuel is made out of uranium, with an increased percentage of the fissionable isotope, U-235, which is needed to sustain a nuclear chain reaction. Once the fuel is placed in the reactor and the chain reaction is started, the fuel is bombarded with high energy radiation, sustaining the nuclear fission process, which makes the fuel much more intensely radioactive. Although a single fuel rod cannot sustain a nuclear chain reaction by itself, its enhanced radioactivity does make it dangerously hot.

 

Without constant cooling, the fuel rods in a nuclear reactor, even without a chain reaction in progress, will rise to a temperature of thousands of degrees, hot enough to melt the metal outer sheathing of the fuel rods, and releasing the dangerously radioactive fuel itself in molten form.

 

FINDING AND HELPING THE SURVIVORS

 

While Japanese engineers were desperately trying to prevent such a nuclear meltdown from taking place in the aftermath of the tsunami, government authorities were struggling to bring enough fresh water, food and emergency supplies to the stunned survivors in the devastated towns along Honshu’s northeastern coastline. Japan has mobilized 100,000 troops to assist in the rescue and recovery efforts.

 

Prime Minister Kan said that his the government was exploring the possibility of delivering food, water and emergency supplies to the stricken areas by sea or air, given the damage done to the roads in the north by the quake and the tsunami. Despite the damage, Kan said Monday that the rescue efforts had found 15,000 survivors of the disaster so far.

 

Perhaps the most unusual of the tales of rescue belongs to Hiromitsu Shinkawa, a 60-year-old man from the town of Minami Soma, who was swept out to sea by the tsunami along with his house. A Japanese destroyer found him Sunday floating 9 miles off the shore of Fukushima Prefecture, waving a makeshift red flag while standing on a piece of his house’s roof. Shinkawa was apparently safe and unharmed, but deeply saddened because he had lost his wife who was swept away by the tsunami.

 

Because of the damage to its nuclear generating plants, Japan is now short of electricity. On Monday, the Japanese government began implementing a series of rolling blackouts across portions of the country including Tokyo, which has 13 million people.

 

Sendai, a northern port city of one million people, was among the hardest-hit areas. A day after the quake hit, oil-storage tanks along the coast burned brightly, sending a plume of black smoke nearly a mile into the sky. Fires could be seen burning in many of the city’s industrial areas days later.

 

NORMAL LIFE IN JAPAN COMES TO A HALT

 

The quake hit at 2:46 p.m. local time, and was felt strongly throughout Japan. In Tokyo, office buildings swayed. Train and bus service was stopped. Millions of households lost power. Cell phone service was also interrupted, causing long lines to form at the few remaining public phones on the streets of Tokyo. Millions of Japanese children had to walk home from school. The damage and disruption was aggravated by more than 100 powerful aftershocks which struck in the three days after the first jolt. Scientists warned that more aftershocks were likely, and could be almost as strong as the 9.0 monster quake that launched the tsunami.

 

To the north, along the coast, the unstoppable waters of the tsunami swallowed homes, cars, trees, people and anything else in its path.

 

DEVASTATION IN THE LIGHT OF DAY

 

“The tsunami was unbelievably fast,” said Koichi Takairin, a 34-year-old truck driver in Sendai who was inside his sturdy, four-ton rig when the wave hit. “Smaller cars were being swept around me. All I could do was sit in my truck.”

 

Even his big rig could not long withstand the onslaught of the waters, and he soon joined the steady flow of survivors who walked along the road away from the sea and back into the city the next morning.

 

In the light of day, the devastation from the tsunami was readily apparent. Smashed cars and small airplanes were jumbled against buildings near Sendai’s local airport, several miles from the shore. Felled trees and wooden debris lay everywhere as rescue workers in boats nosed through the murky waters left behind by the giant wave and around flooded structures, looking for survivors. Many coastal roads were blocked by mudslides.

 

The landscape was littered with a bizarre mix of vehicles, cabinets, sofas, and a doll, heaped in a pile outside the remnants of a house. A white car sat precariously at the top of a sloped house.

 

Local residents waited silently in lines that stretched blocks for food, water and gas. Despite the devastation surrounding them, the people were calm and orderly.

 

Cameron Peek, a 23-year-old American who teaches English in Sendai, was one of 400 to 500 people staying at a local shelter. “We have enough space and food,” he said. “People have been taking cardboard boxes from convenience stores and making beds. Everybody seems pretty spent.”

 

TENS OF THOUSANDS STILL MISSING

 

Japanese officials were concentrating on rescue, recovery and aid efforts throughout the coastal areas north of Tokyo hardest hit. Days after the disaster struck, many areas still didn’t have the emergency supplies they needed, according to those organizing the relief efforts. There was not enough food or clean water and, in many places, no heat. Tens of thousands remain missing, beyond the reach of rescue workers.

 

Satellite images showed Japanese coastal towns where a mosaic of colorful rooftops had been churned into mush. In the town of Rikuzentakata, in Iwate Prefecture (the Japanese equivalent of a county), only 5,900 of the town’s 23,000 residents had taken shelter. All the rest were unaccounted for.

 

The police chief of Miyagi, among the hardest-hit northeastern counties, said that there is “no question” that at least 10,000 people in the prefecture of 2.3 million are dead. Other county jurisdictions in the northern part of Japan’s main Honshu island are expecting death similar tolls.

 

A Japanese news agency reported Monday that 2,000 bodies of victims had been found in Miyagi.

 

A SHORTAGE OF COFFINS

 

In an ominous move, Japan’s Health Ministry Tuesday waved much of the paperwork needed to conduct a funeral in the country, and warned of a growing shortage of facilities to handle all the dead bodies. There has also been a nationwide run on body bags and coffins.

 

Youka Ishi, who works at an office two miles from the Miyagi coast, said that roughly 2,700 buildings closer to the water “have been swallowed by the wave and there is nothing left.”

 

“I know, through my work as a welfare worker, about 40 or 50 elderly people in that area,” Ishi said. “I have not been able to contact any of them since the earthquake.”

 

The town of Minami Sanriku about 3 miles from the Pacific coast, was reduced into a massive pile of wood that used to house some 20,000 residents. The scene there was eerily silent. Emergency rescue officials said they didn’t think anyone was still alive under the rubble. About half of Minami Sanriku’s population was still unaccounted for.

 

A Red Cross official said that in the coastal town of Ishinomaki, the local hospital feared it was about to run out of food and milk for babies.

 

A CITY SPLIT IN TWO

 

As the sun rose Monday over the center of Sendai, which is the economic hub of northern Japan, the scene looked deceptively normal. Three days after the disaster struck, traffic lights and vending machines were working.

 

In fact, the city of Sendai has been divided in two. Downtown office blocks and fancy boutiques were largely untouched by the disaster. The dividing line is an inlet from the sea, now swollen with tires, the remains of houses and other detritus left by the tsunami. The other side is a mud-clogged expanse of wreckage and ruin where chaos reigns in what had been the city’s thriving industrial zone. There Monday, a dark cloud of smoke wafted over a wasteland of smashed houses, uprooted trees and heaps of garbage.

 

Cars crushed like tin cans that had been tossed by the tsunami lay scattered next to a primary school. A clock on the outside wall of the school remained stuck at 2:46, the time the quake struck. Black birds circled over crumpled wooden houses torn from their foundations.

 

In the foundations of one vanished house, a hair dryer, a heater and cooking pots peeked out from a field of mud. A family whose house was flattened returned to find a sodden photo album but not much more.

 

A military helicopter clattered overhead toward the battered but still standing steel factory, now spewing smoke from a fire ignited by the quake that was still burning more than three days later.

 

Masahiru Watanabe returned to see the steel factory where he had worked. Gasping in disbelief, he said he hoped to one day return to his job, but did not expect that to happen any time soon.

 

He was working Friday when the tsunami hit. He took shelter on the top floor of a three-story building. When water rose to his chest, he went up to the roof. He was not able to leave until the water receded the next day. “Terrible, terrible,” he muttered as he watched smoke continue to pour from the seafront steel factory.

 

THE TSUNAMI WAS WORSE THAN THE EARTHQUAKE

 

It is quite possible that the tsunami did more damage and inflicted more casualties than the earthquake. Despite its massive 9.0 magnitude, the earthquake hit far enough offshore and away from Japan’s largest cities that the damage done to the buildings in those cities was only moderate. That is largely due to the fact that the Japan has the toughest anti-earthquake building code in the world. The code was adopted in the aftermath of the devastation caused by the 6.8 magnitude Kobe earthquake of January 17, 1995, which killed 6,434 people and left 300,000 homeless. The new building standards were made mandatory, not only for new construction, but also for existing mid-rise and high-rise Japanese buildings which had to be retro-fitted.

 

The Japanese have also taken measures to guard against damage from tsunamis. They have restricted construction in low-lying areas that are particularly vulnerable to tsunamis near the coast, and have built an extensive tsunami early warning system.

 

Japan is in the active earthquake zone known to geologists as the Pacific Rim of Fire. Japan’s worst earthquake in modern times hit on September 1, 1923, and claimed 140,000 lives, mostly in Tokyo and the port city of Yokohoma. It had a magnitude 7.9, about the same as the 1906 San Francisco quake.

 

That death toll is comparable to the casualties which Japan suffered during the US strategic bombing campaign in World War II. That campaign included the firebombing of Tokyo on March 10, 1945, which killed an estimated 100,000 people. The campaign concluded with the dropping of atomic bombs on the Japanese cities of Hiroshima and Nagasaki in August, 1945, prompting the Japanese to surrender, ending World War II.

 

WHY CRITICAL REACTOR COOLING SYSTEMS FAILED

 

As urgent rescue and relief efforts continued, there was growing concern about the deteriorating situation at the Fukushima Daiichi nuclear plant along Japan’s northern coast, which was heavily damaged by the tsunami. There were also quake and tsunami-related problems reported at two nearby nuclear reactor sites, at Daini, also in the county of Fukushima, and at Onagawa, but they were not nearly as serious as the trouble at Daichi.

 

The initial earthquake was not the cause of the problem. Three reactors at the Daiichi plant had already been shut down for routine refueling before the quake hit, and they posed no danger at all.

 

The three operating reactors at the site initially functioned as designed. They automatically shut down the nuclear chain reactions in their cores as soon as the earthquake hit. Then diesel standby generators at the plant started up immediately when the national electric power grid went down due to the earthquake.

 

The primary purpose of the generators was to maintain uninterrupted power to run the electric pumps circulating fresh water through the core to cool the reactor fuel rods and prevent the possibility of a meltdown.

 

The real problems at the Daiichi plant began an hour after the earthquake, when the giant tsunami wave arrived and rolled over the sea wall protecting the backup generators, flooding them out.

 

A second battery-operated backup system then kicked in to keep the coolant circulating within the reactor cores, but the batteries were only sufficient keep the cooling system running for several hours.

 

Japanese officials rushed replacement generators and additional batteries to the plant. Even after they arrived, the substitute power sources could not be hooked up to the cooling systems, because the key electrical connections were in the plant’s basement, which was flooded by the tsunami waters.

 

The core cooling system is the single most critical safety system in any nuclear reactor. Its failure could not only destroy the reactor, but also lead to the release of deadly amounts of radiation, contaminating the site and the area for miles around.

 

WHAT IS THE CHINA SYNDROME?

 

The worst case nuclear meltdown scenario, nicknamed the “China syndrome,” envisions reactor fuel getting so hot that it melts through the stainless steel containment vessel around the reactor, and keeps going, with its intense heat allowing it to penetrate anything else it touches. The name “China Syndrome” originated from the idea that molten fuel from an American reactor could melt through the crust of the Earth and come out on the other side in China.

 

That is not a realistic possibility, but the destructive potential of a release of superhot reactor fuel into the environment is a truly frightening prospect which was only glimpsed during the Chernobyl disaster 25 years ago. In addition to the release of deadly quantities of radioactivity, the intense heat could trigger fires and explosions that would be very difficult to bring under control.

 

MISLEADING PUBLIC STATEMENTS

 

One by one, as the cooling systems in the three Daiichi reactors began to fail, Japanese engineers had to face the real possibility that a partial fuel rod meltdown had already occurred.

 

At first, engineers for the Tokyo Electric Power company, which owns and operates the plant, insisted that the situation was under control. Nevertheless, as a precaution, Japanese government officials ordered the evacuation of civilians living near the Daiichi plant. When plant officials later admitted that they had lost control of the temperature in the reactor cores, government officials expanded the evacuation zone, ordering 200,000 residents in the area to leave their homes.

 

By Tuesday, plant officials had ordered most of the 800 workers to evacuate for their own safety, leaving just 50 workers behind to try to keep cooling seawater flowing into the damaged reactors, in order to prevent a full blown Chernobyl-type catastrophe.

 

OLDEST REACTOR THE FIRST TO FAIL

 

The first reactor core to overheat was unit 1, the oldest in the complex, which had been built by General Electric and first put in service in 1971. The normal operating lifespan for a nuclear reactor is 40 years, and unit 1 had originally been scheduled to be decommissioned this month. However, Tokyo Electric Power had applied for an extended license to permit the reactor to keep operating because of a shortage of spare generating capacity to replace the electricity that it had been generating.

 

When unit 1’s cooling system failed, engineers adopted a desperate measure to keep the core from overheating. They used fire trucks to pump raw seawater into the reactor building in an attempt to keep the superhot fuel rods in the reactor core underwater.

 

There are two problems with doing that. The first is that the seawater contaminates all of the equipment in the reactor core. Even after the situation is brought back under control and the seawater is pumped out, the reactor will likely never be able to operate again.

 

The second problem is that as the seawater hits the superhot fuel rods, it turns to steam, rapidly building up the air pressure inside the reactor. This, in turn, makes it more difficult to keep pumping cool seawater into the core to keep the fuel rods from melting. At some point, to maintain an adequate flow of water into the reactor core, the engineers have to reduce the air pressure inside the reactor by releasing it to the atmosphere.

 

PRESSURE RELEASES LEAD TO HYDROGEN EXPLOSIONS

 

Such a release could be a public safety hazard. If the high heat has already oxidized and cracked the zirconium alloy sheathing of the fuel rods, some of the radioactive byproducts of the nuclear chain reaction, including the isotopes of iodine 131 and cesium 137, will be released into the air inside the reactor. When the reactor is vented, the iodine and cesium will go into the atmosphere, creating radioactive fallout that wind currents could transport around the world.

 

Furthermore, if the sheathing around the fuel rods reaches temperatures above 2,000 degrees, the zirconium alloy will start to react with the cooling water, forming zirconium oxide (a kind of rust). This makes the sheathing brittle and more prone to cracking. The chemical reaction with water creating zirconium oxide also releases potentially explosive hydrogen gas. When that hydrogen is released into the atmosphere, the tiniest spark can ignite a powerful explosion, which may do further damage to the structures of the reactor.

 

BLAST KNOCKED OUT ANOTHER REACTOR COOLING SYSTEM

 

That is what triggered the blast outside unit 1 at the Daiichi plant Saturday afternoon. Fortunately, the explosion did not damage unit 1’s steel containment vessel, although it did destroy parts of the outer concrete shell around the reactor unit.

 

The same scenario was repeated Sunday, after engineers at the plant were forced to bring seawater into the core of reactor unit 3 to control its temperature, and then vent the reactor to the atmosphere to relieve the steam pressure building up inside. Once again, the steel containment vessel survived, but the blast did other significant damage, knocking out the cooling system for reactor unit 2, which had been operating, at least to some extent, up to that point.

 

Further complicating the situation at unit 3 was the fact that it uses a different mix of nuclear fuel than the other two reactors at the plant. Unit 3 uses a fuel called MOX which contains a percentage of reprocessed plutonium. Aside from being one of the few substances which can sustain a nuclear chain reaction, plutonium is also one of the deadliest poisons known. Inhaling even very small quantities of plutonium can be lethal.

 

STUCK VALVE COMPLICATES COOLING PROBLEMS

 

On Monday, yet another set of problems surfaced at the unit 2 reactor. There, too, the failure of the cooling system forced engineers to pump seawater into the core. However, when steam pressure built up in the reactor building, engineers found themselves unable to open the vents to release it. The increase in steam pressure made it more difficult to pump cooling seawater into the core, allowing the fuel rods to be exposed for several hours. It is believed that once the water level fell below the tops of the fuel rods, they began to melt down.

 

Tuesday morning engineers at the plant finally succeeded in opening the balky vent valve, allowing them to relieve the steam pressure inside the containment building and resume pumping water into the core of unit 2. But by then the damage to the fuel rods had already been done, leading to the explosion that apparently damaged unit 2’s critical steel containment vessel.

 

Plant engineers suspect that this explosion damaged the integrity of the containment vessel, because after they resumed pumping seawater into the reactor, the water level inside the core still failed to rise. Another indication that the fuel rods are damaged and the containment vessel is leaking, is a sharp rise in the radiation levels measured around the unit 2 reactor since the Tuesday morning explosion.

 

STEEL CONTAINMENT VESSEL THE LAST LINE OF DEFENSE

 

A crucial difference between the Japanese reactors and the Chernobyl reactor which blew up in 1986 is that Chernobyl did not have a steel containment vessel surrounding the core.

 

The integrity of the steel containment vessels of units 1, 2 and 3 at the damaged Daiichi plant, was the last line of defense preventing the situation from becoming a rerun of Chernobyl, which was the worst nuclear accident in history.

 

The accident at Chernobyl was due to operator error, leading to a catastrophic failure of its coolant system. The explosion which then ripped apart the reactor forced the evacuation of over 300,000 people from areas of the Ukraine, Belarus and Russia, including all 50,000 people who lived in the nearby city of Pripyat. To this day, nobody is allowed to enter an exclusion zone around the destroyed reactor with a radius of 19 miles.

 

Fifty Chernobyl reactor staff and emergency workers received lethal doses of radiation while trying to bring the accident under control. Public health experts estimate that 4,000 more people among the 600,000 who received the greatest exposure to radiation fallout from Chernobyl across Eastern Europe will ultimately die from cancer as a result, and an unknown additional number have suffered serious medical consequences from it.

 

All three of the damaged nuclear reactor units at the Daiichi plant are more than 30 years old. They went into service before the accidents at Three Mile Island and Chernobyl, and their design is now considered to be obsolete. Western nuclear reactors built today are designed in such a way that they are inherently safer. If the cooling systems in the new reactors fail, for any reason, their cores are designed to cool down on their own, eliminating the possibility of a meltdown.

 

FIRE IN THE HOLDING POOL

 

The most recent problem at the plant was the fire in the spent fuel rod holding pool on the roof of reactor unit 4. Because spent fuel rods are still intensely radioactive, they generate their own heat, even after they are removed from the reactor. That is why they are stored in a deep pool of water, and must be constantly cooled by recirculating water to keep the fuel rods from boiling the water in the pool away.

 

Because the cooling system at the Daiichi plant has been down since the earthquake hit Friday, the temperature of the water in the spent fuel rod pools has been steadily climbing. The last temperature reading of the water in the pool at unit 4, taken Monday, was 183 degrees Fahrenheit, just 29 degrees below the boiling point. It is also believed that the pool at unit 4 was exposed to the air because of structural damage done by the hydrogen explosions at units 1 and 3.

 

By Tuesday, the water in the holding pool at unit 4 had boiled away, exposing the spent fuel rods to the air. The fuel rods then caught fire, spewing radioactive byproducts of the nuclear fission chain reaction into the atmosphere. This has led to a sharp rise of radiation levels around the plant, and higher than normal levels of radiation measured in Tokyo, 170 miles to the south.

 

CRISIS AT UNIT 2

 

The New York Times reported that by Tuesday, the situation at the Daiichi plant was completely out of control, and that officials of Tokyo Electric Power were in a panic. Reporters noted that at press conferences company spokesmen were refusing to give direct answers to some of their questions, and suspected that they were still trying to minimize the true seriousness of the situation.

 

The Japanese government has requested technical help from experts at the US Nuclear Regulatory Commission and the UN’s International Atomic Energy Agency. It is also distributing potassium iodide pills to those who are in the vicinity of the plant. The pills slow down the absorption by the thyroid of the radioactive iodine now being released into the atmosphere from the damaged reactor fuel rods.

 

In an early response to the Japanese emergency, the US Navy dispatched some of its ships to provide emergency supplies and assistance, including the US aircraft carrier Ronald Reagan, which was on patrol not far away. But the carrier had to turn back Sunday when it ran into a cloud at sea containing radioactive debris spewed out by the damaged Japanese reactors about 100 miles offshore.

 

JAPANESE GOVERNMENT’S CREDIBILITY GAP

 

As the growing seriousness of the situation at the Daiichi plant emerged, Japanese officials came under intense criticism for their initial, misleading assurances that public safety was not in danger. Their failure to be honest with the Japanese public about the crisis has undermined their credibility.

 

The admission that the reactor cores at Daiichi could already be in partial meltdown has further alarmed the Japanese public. There was already concern about the country’s heavy reliance on nuclear energy as a substitute for oil and coal, and reports of previous problems at the country’s nuclear reactors which had been covered up.

 

Despite the devastation it has suffered over the past week, Japan remains the best prepared country in the world to deal with major earthquakes and tsunamis. The causes for the accident at the Daiichi nuclear power plant will doubtless be the subject of intense investigation for years to come.

 

The problem originated forty years ago with the failure of the plant’s designers to anticipate that a tsunami launched by an 9.0 magnitude earthquake would be able to short out the backup power systems running its water pumps. Whether that problem was compounded further by avoidable errors made by the plant’s operators remains to be determined.

 

The Washington Post contributed to this story.

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