In the early days of civilian nuclear power, there have been a number of small accidents in different countries, but usually there was little release of radiation. Workers were exposed to it, and four died, one in Yugoslavia, one in Argentina, and two in Japan.83 This does not include deaths in Russia. The two well-known, large accidents are Three Mile Island and Chernobyl.

At Three Mile Island in Pennsylvania, USA, the 1-GW Unit 2, a PWR, had a problem in March 1979. A mechanical failure was compounded by operator error. A pump for the cooling water stopped, and the water got hot, increasing the pres­sure. Automatically, a relief valve opened to let the steam out into the containment building, and control rods dropped in to stop the chain reaction. The relief valve was supposed to close at a certain pressure, but it got stuck open. The hot fuel rods continued to produce steam, and most of the water was lost out the open valve. The operators misinterpreted the signals and thought that there was too much water, so they shut down the pumps, making things worse. Only the bottom of the fuel elements was covered with water. The tops got so hot that the cladding electrolyzed steam into hydrogen, and a hydrogen bubble was formed, preventing water from entering for days. The fuel melted, and 700,000 gallons of radioactive water covered the floors of the buildings [41]. Although the people in surrounding areas were scared and were evacuated, only a small amount of radioactive material escaped. There were no deaths. Statistically, the amount of radiation could have caused three deaths in 20 years, but none has been reported.

The Three Mile Island accident turned a lot of Americans against nuclear power, but compare its safety with that of other energy sources. In 2010 alone, we have had the methane explosion in a West Virginia mine which killed 25 miners, followed by the Deepwater Horizon disaster in the Gulf of Mexico, which killed 11 workers. In each case, families waited and waited for good news about their loved ones, but in vain. The grief is repeated hundreds of times all over the world. The oil leak fol­lowing the fiery destruction of the Deepwater drilling platform was far larger than the Exxon Valdez spill in Alaska and covered hundreds of square miles of the Gulf. Both aquatic wildlife and migrating birds suffered from the environmental damage. Compared to the fossil-fuel industry, a well-regulated nuclear industry is a far safer way to get energy.

The Chernobyl accident is another matter. The dire consequences of the accident were caused by the organization of the Soviet Union.84 Failures were covered by lies. Tight secrecy kept workers from learning from the experiences of others. Those in command made policies without caring about the actual situations they covered. The chief engineer disregarded the protocols anyway. Workers were not well trained to know about the dangers, and they disregarded orders. One of the four reactors at Chernobyl in the Ukraine was being shut down for maintenance. The chief engineer decided to test whether power could still be produced while shutting down. He did not consult the safety personnel or the set rules. The workers turned off safety devices. The control rods were withdrawn to get power while the chain reaction was slowing down due to xenon poisoning. A decrease in cooling water caused the fuel rods to heat up, increasing the power output. The reactor had not been designed to shut down automatically when this happens. There was a runaway reaction and a power surge that ruptured fuel tubes. The hot fuel reacted with water to cause a steam explosion which blew off the 1,000-ton top of the reactor. This broke all the fuel tubes, and a second explosion sent most of the reactor core into the air.

The explosion was like the volcano in Iceland that erupted in 2010, stopping all air traffic in Europe. This time, a radioactive cloud went as high as 10,000 m (30,000 feet), carrying 50 tons of nuclear fuel. The surrounding area was sparsely populated; a nearby village was in great danger. Nonetheless, the man in charge, arriving from Moscow, gave orders not to evacuate because it would create panic. It was a plasma physicist, Evgeny Velikhov, who finally convinced him that people had to get away. Meanwhile a large crew (200,000 in the first year) was trying to clean up the mess. They were walking directly on radioactive material, receiving a lethal dose within minutes. Winds carried the radioactivity all over Europe, but where it landed was random, depending on rain. Most of the volatiles were iodine-131 and cesium-137. The iodine fortunately has a half-life of only eight days, but the cesium lasts for 30 years. The Cs137 carried 500 times more radioactivity than created by the bombs on Hiroshima and Nagasaki.

Statistically, health experts calculate that this accident would cause 30,000 deaths in 20 years. However, this is still a small number compared with other types of accidents. It amounts to a probability of 0.6 deaths per 100,000 people per year. For a well-regulated industry with accidents like that at Three Mile Island, the figure is 0.00007 per 100,000 per year. This is to be compared with 16 for motor vehicle accidents, 0.41 for airplanes, and 5.15 for falls [41]. Falls were considered earlier in the Solar Energy section. Chernobyl was a lesson in bad management, but it will never happen again. Nuclear power poses less risk than almost anything we do.