The nature of nuclear

Himal Southsian, 21 March 2011

By M V Ramana, A H Nayyar and Zia Mian

The lessons of Fukushima.

A week after the 11 March earthquake and tsunami in Japan, there were already 7000 confirmed deaths with over 10,000 people still missing. This disaster was compounded by the nuclear accidents at four out of the six reactors at the Fukushima-Daiichi plant, in the country’s northeast, and the continuing threat of widespread radioactive contamination. Radiation levels close to the reactors have been above the legal limit, while traces of radiation have arrived on the West Coast of the United States, 5000 miles across the Pacific Ocean. There are many lessons for Southasia from the earthquake and tsunami about the need to be better prepared for natural disasters, to anticipate and take precautions in designing buildings, public infrastructure and communications, to assume that everything that can go wrong will go wrong, and to be organised and transparent. But there are as many lessons regarding the nuclear accident and what it means for Southasia.

This is a critical time for nuclear energy in this region. India has 20 operating nuclear-power reactors, with several more under construction and plans for a vast expansion over the next few decades. Pakistan has two operating nuclear plants, another one under construction, and plans to buy two more as part of a planned eight-fold increase in its reliance on nuclear energy in the next 30 years. Both countries also have military reactors that are part of their nuclear-weapons programmes. Bangladesh and Sri Lanka have plans to build their first nuclear reactors. Today, all should stop and think about what they can learn from the Fukushima accident.

The first lesson is that the nuclear accident happened in Japan, in a country that is technologically very advanced and is a manufacturer of nuclear reactors which it supplies to other countries. Japanese expertise in nuclear technology is second to none. A loss of control over the destroyed nuclear reactor is not due to any technological weakness or lack of skilled operators. Previous serious reactor accidents took place at Chernobyl, in the Soviet Union, in 1986, at Three Mile Island in the US in 1979, at Windscale in the UK in 1957 and at Chalk River in Canada in 1952. All these accidents happened in spite of sound technical expertise. It is in the nature of nuclear technology.

Despite the nuclear industry’s assurances about safety, reactors and other nuclear facilities are susceptible to major accidents. But after each accident, the passage of time dulls the memories and allows advocates of nuclear power again to assert that nuclear energy is a safe source of power.

Small failures

The second lesson is that accidents have occurred in a wide variety of reactor designs and there is no design that can claim to be completely immune to any kind of catastrophic accident. The five most serious accidents before Fukushima were in five different reactor designs.

The Fukushima plants are boiling water reactors, similar in basic design to the Tarapur I and II reactors near Mumbai. As in all plants, even though the reactors were shut down automatically once the earthquake hit, the nuclear fuel in the cores continued to produce heat, albeit a small fraction of that produced when the reactor is operating normally. Pumps must continue to circulate water to remove this heat, or the reactor fuel heats up and will melt. Nuclear-reactor designers put in multiple systems to ensure such cooling. But at Fukushima, all of these safety systems failed. Hot nuclear fuel was exposed to the air, releasing radioactive gases into the atmosphere. The exposed fuel is also a source of hydrogen, which produced the explosions that damaged the four reactor buildings and the inner concrete-and-steel containment at one of the four units.

The third lesson is that small failures can combine to produce disastrous results and this cannot be avoided. At the Fukushima reactors, many safety systems failed simultaneously or serially. For example, on 14 March, the Tokyo Electric Power Company, which operates the Fukushima plants, revealed that some safety valves did not open, for unknown reasons. This made it difficult to pump cooling water into the reactor. To anticipate every such possible eventuality and build in fail-safes would make reactors impossibly complicated. Also, each additional component is something else that can go wrong. Eventually, reactors become too expensive to build.

The fourth lesson is that extreme natural disasters only make nuclear accidents more likely. It is important to remember that neither the Three Mile Island accident or the Chernobyl disaster, nor Windscale nor Chalk River, needed a natural disaster to start them off. Reactor accidents are more likely during earthquakes because they simultaneously affect large parts of the plant, taking out multiple safety systems or create multiple failures. Common failures are also caused by fires. It was a fire that caused the blackout in Narora in 1993, India’s closest brush with a major nuclear accident.

The fifth lesson is that new reactors might not always be safer than old ones. It is true that many of the Fukushima reactors were designed during the 1960s. But what happened was that operators lost the ability to cool the core of the reactors and, as a result, the pressure inside the reactor vessel could only keep building as water boiled away into steam. As the fuel in the core started to melt, it interacted with the water or steam to produce explosions. No currently existing reactor will likely survive all of that any better than the Fukushima reactors.

Measured exit

The sixth lesson is that reactors and people do not mix. Those who have been most affected by the nuclear accidents at Fukushima are, of course, the workers, who have been braving explosions and high levels of radiation exposure to try to maintain control over the reactor and associated facilities. Next to them are the inhabitants of the areas near the plant, nearly 200,000 of whom have been forced to leave their homes. In Southasia, there are some reactors close to major population centres or major rivers that provide vital water for drinking and agriculture.

Take for example Pakistan, which has a nuclear reactor on the Karachi coast and is vulnerable to tsunamis. Built over 40 years ago, the Karachi plant was originally far away from the populated areas of the city. Since then, however, many housing schemes have sprung up within 20 km of the site. A sea breeze blows over the plant towards northern parts of Karachi.

In Japan, the population within 20 km of the Fukushima reactors has been evacuated, and those up to 30 km away have been told to remain confined to their homes to avoid being contaminated by radioactivity. The US has told its citizens in the area to move at least 80 km away from the reactor. It is unthinkable that such arrangements would be possible in Karachi.

Around the world, people are today rethinking nuclear energy. Speaking in the German Parliament this week, the chancellor of Germany, Angela Merkel, someone who has been committed to nuclear energy and had adopted a policy of extending the lifetime of that country’s 17 nuclear power plants, said ‘when … the apparently impossible becomes possible and the absolutely unlikely reality, then the situation changes.’ She announced a new policy of a ‘measured exit’ from reliance on nuclear energy. Southasian leaders would do well to pay heed.

M V Ramana and Zia Mian are physicists at Princeton University’s Program on Science and Global Security, and A H Nayyar is a Visiting Professor of Physics at LUMS, Lahore.