Chernobyl Unit 4 reactor causes

Lithuania is more dependent on nuclear power than any other country in the world. Its two 1500-megawatt reactors produce more than 80 percent of the country s electricity. The reactors, however, are the same design as the unit that caused the Chernobyl disaster. With both reactors working, Lithuania can produce almost twice as much energy as its domestic demand, allowing the country to sell the excess to other nations. If one unit were shut down, however, the country... 

Nuclear power has achieved an excellent safety record. Exceptions are the accidents at Three Mile Island in 1979 and at Chernobyl in 1986. In the United States, safety can be attributed in part to the strict regulation provided by the Nuclear Regulatory Commission, which reviews proposed reactor designs, processes appHcations forUcenses to constmct and operate plants, and provides surveillance of all safety-related activities of a utiUty. The utiUties seek continued improvement in capabiUty, use procedures extensively, and analy2e any plant incidents for their root causes. Similar programs intended to ensure reactor safety are in place in other countries. 

While we recognize the major concern attendant on widespread use of nuclear power in particular reactor malfunction, we note that no reactor accident that harmed any member of the public has occurred in any facility meeting international safety standards (Chernobyl did not meet the standards). Eossilfuel pollution from power plants is estimated to cause 40,000 to 70,000 deaths per year in the United States alone. 

Everyone s worst fears about nuclear power became a reality in tlie later part of April 1986. A large Soviet reactor - unit number 4 at Chernobyl, 80 utiles nortli of Kiev, and only 3 years old blew out and burned, spewing radioactive debris over much of Europe. Radiation levels increased from Sweden to Britain, tlirough Poland, and as far soutli as Italy. The damage caused to tlie environment far surpassed tlial due to tlie accident at Tliree Mile Island. 

Only two earlier reactor accidents caused significant releases or radionuclides the one at Windscale (United Kingdom) in October 1957 and the other at Three Mile Island (United States) in March 1979 (UNSCEAR-1982). While it is very difficult to estimate the fraction of the Windscale radionuclide core inventory that was released to the atmosphere, it has been estimated that the accident released twice the amount of noble gases that was released at Chernobyl, but 2,000 times less and Cs (DOE-1987). The Three Mile Island accident released approximately 2% as much noble gases and 0.00002% as much l as the Chernobyl accident. 

There have been two major accidents (Three Mile Island in the United States and Chernobyl in the former Soviet Union) in which control was lost in nuclear power plants, with subsequent rapid increases in fission rates that resulted in steam explosions and releases of radioactivity. The protective shield of reinforced concrete, which surrounded the Three Mile Island Reactor, prevented release of any radioactivity into the environment. In the Russian accident there had been no containment shield, and, when the steam explosion occurred, fission products plus uranium were released to the environment—in the immediate vicinity and then carried over the Northern Hemisphere, in particular over large areas of Eastern Europe. Much was learned from these accidents and the new generations of reactors are being built to be passive safe. In such passive reactors, when the power level increases toward an unsafe level, the reactor turns off automatically to prevent the high-energy release that would cause the explosive release of radioactivity. Such a design is assumed to remove a major factor of safety concern in reactor operation, see also Bohr, Niels Fermi, Enrico AIan-HATTAN Project Plutonium Radioactivity Uranium. 

The partial meltdown of the 1000 MW reactor at Chernobyl, Ukraine, on April 26, 1986 released large amounts of radiocesium and other radionuclides into the environment (Table 27.3), causing widespread radioactive contamination of Europe and the former Soviet Union. Among the reactors operating in the former Soviet Union are 13 identical to the one in Chernobyl, Ukraine, including units in Chernobyl, Leningrad, Kursk, and Smolensk. 

At 01.23 hours on 26 April 1986, Unit No. 4 of the Chernobyl Nuclear Power Station was operating at low power prior to a scheduled shutdown when a sudden, very rapid and uncontrolled power increase occurred. This resulted in the destruction of the reactor core and severe damage to the reactor building. There was a release of radioactive material from the core over the subsequent 9 days. The accident is now known to have occurred as a result of a test which was being carried out by the operators. The manner in which the test was conducted, including the disabling of all the safety systems provided to protect the plant, was the immediate cause of the accident. However, aspects of the reactor design resulted in the adverse response of the reactor which caused its destruction. 

Consider the damage in the last few decades due to the use of nuclear reactors, divided by the amount of available energy produced. Two well-known examples of such damage are at Three Mile Island in the United States in 1979, and even more at Chernobyl in the Soviet Union in 1986. Both of these were caused by human error. At Three Mile Island, the economic damage was great, but there was hardly any effect on health. In Chernobyl, the effect on human health was considerable, but still small compared to the publicity it generated. 

The safety record of the nuclear industry has continued to be generally very good, despite the 1987 accident with a nuclear reactor at Chernobyl, in the Ukraine, which killed a number of workers, caused the abandonment of adjacent communities and farmland, and resulted in radioactive fallout in neighboring countries. It should be noted that these were the first nuclear fatalities since the beginning of the nuclear power industry. It is generally agreed that this unfortunate occurrence was caused by serious design flaws, and that power reactors in use elsewhere are not subject to similar occurrences. Indeed, a somewhat similar yet also very different accident occurred in the United States in 1979 (Three Mile... 

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