Many countries, including Iran, are embracing nuclear power as a source of electricity. But just weeks ago, a massive earthquake in Japan caused significant damage to one of that country's nuclear power plants.
While the international nuclear power industry says it is strongly focused on safety, the events at Japan's Fukushima facility raise concerns that - no matter how carefully designed these nuclear facilities may be - accidents can happen.
It happened on March 11. First, Japan shook violently from an earthquake - now called the most powerful ever to hit that country. Then, immediately after, a tsunami smashed what the earthquake had not destroyed. And, in the path of both was the Fukushima nuclear power plant on the Pacific coast, north of Tokyo.
The dual disasters knocked out power needed to maintain safe cooling levels for the plant's multiple nuclear reactors. Despite emergency efforts, temperatures in the reactor cores rose to dangerous levels.
And then, the worst happened. A day after the earthquake and tsunami, the building housing one of Fukushima's reactors exploded. Two days later, another reactor building was shattered by a blast. And, a day after that, yet another explosion tore apart a third reactor building. The end result was the release of dangerous nuclear radiation, which continues at varying levels today.
Japanese officials evacuated a 20-kilometer zone around Fukushima. Nearly a half million people had to leave their homes. At numerous sites near the plant, people were - and still are - screened for radiation, which was also detected in places far from the scene.
And, the radiation levels at Fukushima forced officials to evacuate most plant workers for days.
Officials monitoring the Fukushima disaster are carefully monitoring the concrete and steel structures called "containment vessels" that encase the nuclear reactors. These containment vessels are designed to prevent radiation from escaping. There are concerns that at least one of the vessels at Fukushima may have been breached.
At the International Atomic Energy Agency in Vienna (IAEA), Safety Director Phillipe Jamet said these structures are vitally important.
"The containment vessels are one of the barriers," said Jamet. "We have to protect the environment and people against radioactivity in case of an accident."
The worst nuclear disaster in history took place 25 years ago at the Chernobyl nuclear plant in Ukraine. The Soviet-built plant did not have containment vessels surrounding its obsolete style of reactors.
Early on April 26, 1986, reactor Unit Four at Chernobyl overheated and exploded, tearing off the roof of the building housing it.
Nuclear radiation spewed into the night sky. And, as people slept, it spread throughout the city of Pripyat, just north of Chernobyl.
At reactor four, the nuclear fuel and the graphite surrounding it were on fire. Authorities sent helicopters to fly over the reactor to dump sand and other extinguishing materials, but it burned for days.
The wind carried radioactive particles from the fire over a wide area. Ukraine, Belarus, Russia. Then, Scandanavia, Britain, and other parts of Europe.
Radioactivity forced officials to create a 30-kilometer-wide no-habitation zone around Chernobyl, sealing off Pripyat.
Thousands of people were sent to Chernobyl to clean up debris from the blast. They also built a structure, called a sarcophagus, to cover the shattered reactor and its radioactive fuel.
Pripyat is now a dead city. Homes, schoolrooms, playgrounds, and other places are crumbling as wild nature reclaims the land. Pripyat once had some 50,000 residents. Now they are gone, perhaps forever. Only the artifacts of their lives remain behind, rotting to dust.
The Soviet government said at least 31 fatalities at the Chernobyl plant were directly linked to the reactor explosion. The World Health Organization says another 2,200 deaths can be expected among those who took part in the cleanup. The WHO report added that, in all, Chernobyl could result in 4,000 fatalities from cancer and other radiation-linked causes.
Seven years before Chernobyl, on March 28, 1979, the critical need for reactor containment vessels was proven at the Three Mile Island nuclear power plant in the Eastern U.S. State of Pennsylvania.
A loss of reactor cooling water caused a partial meltdown of the nuclear fuel in the plant's Unit Two. But, the containment vessel remained intact and shielded the environment from the damaged core.
The Three Mile Island incident compelled the U.S. nuclear power industry to significantly toughen safety and operating standards.
"It just caused a re-examination and a need for continuous improvement in our operations - to not get complacent, to have better training, to improve our off-site response capabilities in terms of emergency planning," recalled Tony Pietrangelo Senior Vice President of the trade group, The Nuclear Energy Institute.
Nuclear power operators worldwide say safety tops their priority list, and is constantly reinforced through training and monitoring of plant operations.
The same is being said by the Atomic Energy Organization of Iran, which has completed that country's first commercial power plant at Bushehr, alongside the Persian Gulf.
The reactor building of Bushehr Nuclear Power Plant located outside the southern city of Bushehr, Iran
(August 2009 file photo)
Iran has finished building its first nuclear power plant, at Bushehr, on the coast of the Persian Gulf. It is expected to be operational later this year. In this second segment of our Nuclear Safety series, we look at the design and construction of Bushehr, and how this facility differs from the Japanese nuclear plant at Fukushima that has suffered major damage in the wake of a massive earthquake.
Northern Japan's massive March 11 earthquake and tsunami left the Fukushima nuclear power plant unable to run its cooling pumps and other safety systems. Within days, three buildings housing nuclear reactors suffered major explosions. And, radiation has been released.
Japan is well-known for earthquakes. Its nuclear power industry has said earthquake safety was included in its facility designs. But recent events have shown that the best of plans sometimes cannot overcome the forces of nature.
Half a world away, another country, Iran, is also well known for earthquakes. Over the years, tens of thousands of people there have died in massive tremors.
Now, Iran is moving into the nuclear age. Its first nuclear power plant, located at Bushehr on the Persian Gulf coast, has been completed. It could begin operating soon.
Construction of Bushehr began in 1974, but was halted by the 1979 Islamic Revolution. The plant was attacked and damaged in the eight year Iran-Iraq war. Construction finally resumed in 1995, with Russia taking over from the German company Siemens.
Engineering Professor Muhammad Sahimi, at the University of Southern California, says the threat of earthquakes was carefully considered when the location was selected.
"The first thing the Atomic Energy Organization of Iran did was extensive studies in terms of the safety of a nuclear reactor from the perspective of earthquakes," noted Sahimi. "Usually, a nuclear reactor is built in an area where the possibility of a major earthquake is very small. As far as I know, there is no major active fault in southern Iran where the Bushehr reactor has been built."
The single Russian VVER-1000 reactor installed at Bushehr, with roughly 1,000 megawatts power output, is comparable to its western counterparts.
Senior nuclear scientist Upendra Rohatgi at the U.S. government's Brookhaven National Laboratory in New York is very familiar with this type of reactor.
"The VVER-1000 is the latest Russian design, which is equal to western designs for pressurized water reactors," noted Rohatgi. "They all have the same safety systems, VVER and the western side [designs], and they all have very good containment systems."
Bushehr's reactor is a completely different design from the much older type that exploded at Chernobyl, Ukraine in 1986. The Iranian reactor, unlike the ones at Chernobyl, is completely encased in a massive concrete and steel containment vessel.
The containment vessel is designed to keep radiation from contaminating the environment should an accident take place. It has multiple layers to provide that protection, as well as strength to stop an impact or explosion from either inside or outside the structure.
Japan's Fukushima nuclear plant has a similar multiple-layer design. But there are fears that despite the design, at least one reactor containment vessel may have been breached. That, observers say, would account for at least some of the radiation that has been released.
The control room of Bushehr Nuclear Power Plant in southern Iran
Iran's Bushehr nuclear power plant has been completed. Russia, which supplied the reactor, is now training Iranians to operate the facility. And the International Atomic Energy Agency, or IAEA, of which Iran is a member, says it is committed to imparting a "culture of nuclear safety" for all member nuclear power operators. As last month's nuclear disaster at Japan's Fukushima power plant shows, such safety considerations can become a life-or-death matter.
Workers at the Fukushima nuclear power plant, north of Tokyo, on the Pacific Ocean coast, have struggled to prevent the spread of radiation following damage incurred by that massive earthquake in March. Their efforts reflect the extensive emergency training they, and other nuclear power workers worldwide, are given. That includes the personnel at Iran's new Bushehr nuclear power plant.
The nuclear power industry will never forget what happened 25 years ago at the Chernobyl facility in Ukraine. There, an experiment with the cooling system - one not provided for in the training regimen - led to a reactor explosion and what became the world's worst nuclear power disaster.
Especially after Chernobyl, the global nuclear power industry has focused on what it calls a "culture of nuclear safety." At The Nuclear Energy Institute - a U.S. trade group, Tony Pietrangelo explains the concept.
"The safety culture exists on a continuum," said Tony Pietrangelo . "You can always work to improve it. It is a questioning attitude. It is professionalism. And again, it is that profound respect for the technology you are dealing with."
One pillar of that safety culture is thorough training for those who will operate nuclear power plants. Russia's state nuclear power entity, ROSATOM, which completed the Bushehr plant after years of delays, is now training the Iranian staff to run it. At the U.S. Broookhaven National Laboratory, senior scientist Upendra Rohatgi describes the training regimen.
"They are providing operator training in terms of classroom [instruction]. Then also, they have full-scope simulators, which are the same as western [in terms of] standards, and then, in-plant training," noted Rohatgi.
Like the aircraft simulators that pilots train on, nuclear power operators can learn how to cope with problems and sudden emergencies without making real-life mistakes that could cause fatalities and devastate the environment.
ROSATOM will remain on-site for the immediate future, as it has done with other client nations such as China and India.
And the International Atomic Energy Agency (IAEA), of which Iran is a member state, will oversee the plant's operation.
The IAEA sends teams of inspectors to nuclear power plants to ensure that best practices are being followed.
"They look at the training programs - how the operators are trained to cope with accidents on simulators, and so on. And, we also look at the qualifications of people to perform maintenance. And also, the preparation of the plant for possible emergencies," explained IAEA Nuclear Installation Safety Director Philippe Jamet.
Iran's Atomic Energy Agency has repeatedly said that as an IAEA member, it will follow that U.N. agency's operational and safety protocols at the Bushehr plant.
But what the disaster at Japan's Fukushima plant makes clear is that the severity of natural events, such as a massive earthquake, can overwhelm even the highest levels of training and attention to safety.
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