On April 26, 1986, the world’s worst nuclear power plant accident occurred at the Chernobyl nuclear power station. Now, 25 years later, the current crisis in Fukushima is being called the “worst since Chernobyl.” Will we avoid another disaster? And further more, in another 25 years, how will we feel about nuclear energy?
Below a comprehensive article on Chernobyl by Philip R. Pryde, as it appears in The Oxford Companion to Global Change (Ed. David Cuff & Andrew Goudie). For further reading, I suggest looking to the newly published volume Nuclear Energy: What Everyone Needs to Know.
The most catastrophic accident ever to occur at a commercial nuclear power plant took place on April 26 , 1986, in northern Ukraine at Chernobyl (Chornobyl’ in Ukrainian). Intense radioactive fallout covered significant portions of several provinces in Ukraine, Belarus, and the Russian Federation, and lesser amounts fell out with precipitation in numerous other European countries. The resultant health and environmental consequences are ongoing, widespread, and serious.
The Chernobyl power station is one of several such complexes built in Ukraine. At the time, it was believed that nuclear energy would entail negligible damage to the environment. Four other large nuclear power complexes have been constructed and Ukraine has a major uranium-mining complex and numerous research facilities.
The Chernobyl reactors utilize a graphite-moderated type of nuclear reactor (Russian acronym, RBMK), with a normal output of 1,000 megawatts. These units are water-cooled and employ graphite rods to control core temperatures. Each reactor houses 1,661 fuel rods that contain mainly uranium-238 plus much smaller amounts of enriched uranium-235. There are several dangers inherent in the design of RBMK-1000 reactors, including the ability of the operators to disengage safety controls, the lack of a containment dome, and the possibility that, at very low power levels, a rapid and uncontrollable increase in heat can occur in the reactor’s core and may result in a catastrophic explosion ( Haynes and Bojcun , 1988 , pp. 2–4).
This was what happened early in the morning of April 26 , 1986. A series of violations of normal safety procedures, committed during a low-power experiment being run on reactor number 4, resulted in a thermal explosion and fire that destroyed the reactor building, exposed the core, and vented vast amounts of radioactive material into the atmosphere. Pieces of the power plant itself were found up to several kilometers from the site of the explosion.
This radiation continued to be released into the atmosphere over a period of nine days, with the prevailing winds carrying the radioactive material initially in a northwesterly direction over northern Europe. The winds later shifted to the northeast, carrying fallout southwestward into central Europe and the Balkan peninsula. The overall result was significant radioactive fallout (mainly associated with rainfall) in Austria, Czechoslovakia, Finland, Germany (mainly Bavaria), the United Kingdom, Hungary, Italy, Poland, Romania, Sweden, and Switzerland. Lower levels of radioactive deposition were reported in Denmark, France, the Benelux countries, Greece, Ireland, Norway, Yugoslavia, and several other European nations (Medvedev 1990 , chap. 6). The republics of Estonia, Latvia, and Lithuania were also directly in the path of the initial plume.
In the Soviet Union, the regions that received the highest levels of radioactive contamination were in the northern Ki
By Charles D. Ferguson
The ongoing Japanese nuclear crisis underscores yet again the risks inherent in this essential energy source. But it should not divert nations from using or pursuing nuclear power to generate electricity, given the threat from climate change, the health hazards of fossil fuels, and the undeveloped state of renewable energy. Instead, the events at the Fukushima Daiichi Nuclear Power Plant should turn more attention to ensuring that nuclear power plants meet the highest standards of safety and protection against natural disasters.
More than 30 nations have commercial nuclear power plants. A further two dozen are interested in having them, including several in earthquake risk areas such as Indonesia, Malaysia and Turkey.
Some nations are pro-nuclear for energy security; some for prestige. Others, including Iran, have invested in nuclear power because they may want the capability to make nuclear weapons. These nations are seeking to acquire uranium enrichment or reprocessing technologies: useful either for producing fuel for peaceful nuclear reactors or fissile material for nuclear bombs.
Although some national leaders profess to be interested in nuclear energy because operating plants do not emit greenhouse gases, this is usually a secondary motivation. If it were their primary concern, nations would invest far more than they have in measures such as energy efficiency and solar and wind technologies.
The Japanese crisis has affected three important criteria: public opinion, safety and economic costs. Governments and utilities have had to grapple with these for decades. Now they must renew their efforts to finance expensive nuclear projects and ensure that existing and future nuclear plants maintain the highest standards — and must be seen to do so by the public.
Building nuclear power plants has always been expensive. For a large reactor with a power rating of 1,000 megawatts or greater, the capital cost ranges from US$4 billion to $9 billion depending on reactor design, financing charges, the regulatory process and construction time. The recent nuclear crisis is likely to change all of these, pushing up costs.
Contemporary plant designs — ‘generation III’ — have better safety features than the 1970s-era generation II designs for the Fukushima reactors, making them more expensive. Some, such as the AP1000 designed by the Westinghouse Electric Company, headquartered in Cranberry Township, Pennsylvania, have passive safety features that do not require technicians to activate emergency systems or electrical power to ensure safety after a mishap. Others, such as Paris-based Areva’s EPR, have advanced active safety systems designed to prevent the release of radioactive material to the environment. Further designs, such as the pebble-bed modular reactor, may prevent nuclear fuel from ever experiencing a meltdown. Concerns were raised about the Fukushima designs as early as 1972, the year after reactor unit 1 began operations. But the nuclear industry opposed shutting down such reactors because 32 were in operation worldwide — about 7% of the world’s total. Almost one-quarter of the reactors in the United States are of this type. The remaining plants of this design should undergo a thorough safety review and, as a result, some may need to close. Since the crisis began, several governments, including China, Germany and Switzerland, have called for increased scrutiny of their plants and a moratorium on plant construction until plant safety is assured. Germany has also shut down its seven oldest reactors.
But phasing out nuclear power worldwide would be an overreaction. It provides about 15% of global electricity and even larger percentages in certain countries, such as France (almost 80%) and the United States (about 20%). Eliminating nuclear power would lead to much greater
This article was originally published by Foreign Policy on March 11, 2011.
A Radioactive Situation
By Charles D. Ferguson
Is nuclear power too risky in earthquake-prone countries such as Japan? On March 11, a massive 8.9-magnitude earthquake shook Japan and caused widespread damage especially in the northeastern region of Honshu, the largest Japanese island. Nuclear power plants throughout that region automatically shut down when the plants’ seismometers registered ground accelerations above safety thresholds.
But all the shutdowns did not go perfectly. Reactor unit 1 at the Fukushima Daiichi Nuclear Power Station experienced a mechanical failure in the emergency safety system. In response, officials ordered the evacuation of residents who live within two miles of the plant. Also, people living between two to 10 miles were ordered to stay indoors. The Japanese government described this order as a precautionary measure.
A worst-case accident would release substantial amounts of radioactive materials into the environment. This is unlikely to happen, but is still possible. Modern commercial nuclear power plants like the Fukushima plant use defense-in-depth safety measures. The first line of defense is fuel cladding that provides a barrier to release of highly radioactive fission products. Because these materials generate a substantial amount of heat, coolant is essential. Thus, the next lines of defense are to ensure that enough cooling water is available. The reactor coolant pumps are designed to keep water flowing through the hot core. But loss of electric power to the pumps will stop this flow. Backup electric power sources such as off-site power and on-site emergency diesel generators offer another layer of defense.
Unfortunately, these emergency power sources were knocked out about one hour after the plant shut down. Although it is unclear from the reporting to date, this power outage appears to have occurred at about the same time that a huge tsunami, triggered by the earthquake, hit that part of Japan.
Sustained loss of electric power could result in the core overheating and the fuel melting. However, three other backup systems provide additional layers of defense. First, the plant has batteries to supply power for about four hours. Second, the emergency core cooling system can inject water into the core. Finally, the containment structure, made of strong reinforced concrete, surrounds the reactor and can under even the most severe conditions prevent radioactive materials from entering the environment.
But the earthquake — the largest in the 140 years of recorded history of Japanese earthquakes — might have caused some damage to the containment structure. Japanese authorities announced that they will vent some steam from the containment structure to reduce the pressure buildup. This action may release small amounts of radioactive gas. The authorities do not expect any threat to the public.
Although a meltdown will most likely not occur, this incident will surely result in significant financial harm and potential loss of public confidence. For example, it was less than four years ago, in July 2007, when the Kashiwazaki-Kariwa Nuclear Power Plant, Japan’s largest, suffered shaking beyond its design basis acceleration. The plant’s seven reactors were shut down for 21 months while authorities carefully investigated the extent of the damage. Fortunately, public safety was not harmed and the plant experienced no major damage. However, the government accepted responsibility for approving construction of the first reactor near a geological fault line, which was unknown at the time of construction. The