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Lessons on nuclear reactor accidents

Publication Date : 02-07-2013

 

Before the Bangladeshi government puts reactor technology to generate power on a fast track, it would be prudent to consider the history of reactor accidents as a background for judging how likely it may be that similar accidents might occur at the Rooppur Nuclear Power Plant.

Nuclear accidents are rated by the International Atomic Energy Agency according to the International Nuclear Events Scale, ranging from 1 (“anomaly”) to 7 (“major accident”).

From 1954 to now, there have been nearly 100 reactor accidents — some minor and others major — but with only local consequences. There are some that can be placed among the worst disasters we have ever experienced. It is these accidents, with ratings 5 through 7 that will be discussed in this article.

Level 7 (Major accident): The Chernobyl, Ukraine, accident of 1986 is the world’s worst nuclear accident. It was caused by inadequately trained personnel conducting unsafe tests on reactors with a history of safety and design flaws. There was an explosion followed by fire that led to a partial meltdown of a reactor’s core. The aftereffects of the accident were great: 30 on the spot deaths; hazardous radioactive material spread over much of Europe; 350,000 people living in the vicinity of the plant evacuated; and about 3.2 million people affected by radiation from 1986 to 2000. According to the World Health Organization, approximately 4,000 people died from radiation-related sickness while Greenpeace claims that more than 200,000 died. The Nuclear Energy Agency estimates that latent deaths over the 70 years after the accident will total between 9,000 and 33,000.

The ecosystem of a large portion of Europe, particularly Belarus, Ukraine, and the Russian Federation, was severely affected by the release and deposition of large amounts of radionuclides in the atmosphere, soil, and water bodies.

The only other Level 7 accident in history is the Fukushima disaster of 2011. It was caused by an earthquake followed by a tsunami, resulting in a complete meltdown of three reactors. The failure of the emergency systems caused an explosion, releasing radiation that contaminated a large area around the plant. Because of the Japanese government’s efficient handling of the situation there were no deaths, but about 160,000 people living in the surroundings had to be evacuated.

Food grown in the area was contaminated and banned from sale. Last month, elevated levels of toxic radioisotopes, such as strontium-90 and iodine-131, have been detected in the groundwater near the plant. Large amounts of highly radioactive spent fuel rods are still stored in the pools next to the reactors.

Level 6 (Serious accident): The only Level 6 accident occurred in 1957 at the Kyshtym plant at Mayak, Russia. The accident happened when a tank containing radioactive waste exploded because of a sudden rise in temperature. Approximately 10,000 people were evacuated from the area around the plant. The disaster also exposed about 500,000 people to dangerous levels of radiation and hundreds of square miles of land were rendered barren. Because of the secrecy surrounding Soviet accidents, the actual number of fatalities remains uncertain. However, according to the Institute of Biophysics of the former Soviet Union, over 8,000 people died so far from the effects of radiation.

Level 5 (Accident with wider consequences): There have been three Level 5 accidents. They are:

1957 Windscale, Cumbria, UK: Following a fire in a reactor core, there was release of radioactive material to the environment. There were no immediate fatalities, but dozens of people died later from radiation-induced cancer.

1979 Three Mile Island, Pennsylvania, USA: A partial core meltdown due to loss of coolant was caused by the malfunction of some safety features and operator confusion. There were no fatalities but small amounts of radioactive material were released into the environment.

1987 Goiania, Brazil: Due to a lack of adequate accounting and inspection procedures for radioactive sources, more than 240 people were exposed to radiation and 4 died when a junkyard dealer opened an old stolen reactor and removed a highly radioactive cake of cesium chloride.

These accidents, caused by design flaws, human error, lack of oversight, meltdowns, fires, and earthquakes, happened despite the many tiers of safety features that were in place at the plants.

After the Fukushima accident, a research study carried out at the Max Planck Institute for Chemistry in Mainz, Germany, concluded that the global risk of a catastrophic reactor accident now is much higher than previously thought.

If Chernobyl was the fuel, then Fukushima was the catalyst that ignited anti-nuclear sentiment all over the world. Fukushima had a profound effect on the safety criteria and procedures followed for the existing plants. It also led many countries to re-evaluate their nuclear programmes. There were immediate shutdowns, gradual phase-outs, and suspension of approvals for new reactors.

These and other accidents should be a wake-up call to judge whether the precautions that will be in place at the Rooppur plant are sufficient or whether the programme should be pursued more slowly and in a way to make greater degrees of precaution possible.

The government must realise that to protect the citizens from the aftereffects of a nuclear accident, it will have to take precautionary measures of a type and on a scale that has no historical precedent in Bangladesh.

Once a reactor is turned on, processes are set in motion that cannot be reversed for a very long time. Hence, the government should do some serious soul-searching before mortgaging the future of 160 million people to a country with a lousy safety record.

Finally, it is obvious that nuclear accidents do happen and they are capable of doing more than immediate damage. We cannot disguise their potentially lethal effects. They destroy not only the present, but also the future. That is why the fears and angst aroused by nuclear accidents are so much deeper.

The writer is a professor in the Department of Physics and Engineering Physics, Fordham University, New York.

 

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