Soviet Union, nuclear reactors

Chernobyl, Soviet Union Nuclear reactor accident 325 300... 

Although the Chernobyl accident was very serious, the defects in design and operating procedures that led to it were so egregious that the accident has tittle relevance to current reactors outside the former Soviet Union. However, it serves as a reminder of the need for rigorous care in the design, construction, and operation of nuclear power plants. 

Two accidents of vastly differing severity have occurred at nuclear power plants. On 28 March 1979, an accident occurred in the nuclear power plant at Three Mile Island, Pennsylvania, USA. The radiation was contained and the small amount released had negligible effects on the health of individuals at the plant. On 26 April 1986 an accident occurred in the nuclear power plant 10 miles from the city of Chernobyl, then part of the Soviet Union. The chain reaction in the radioactive core of one of the four reactors became uncontrolled. Steam pressure rose to dangerous levels there were several explosions and a subsequent fire took several hours to extinguish. Large amounts of radioactive material were scattered over a wide area and into the atmosphere (later descending in a dilute form in rain all over the world). 

In a typical fast breeder nuclear reactor, most of the fuel is 238U (90 to 93%). The remainder of the fuel is in the form of fissile isotopes, which sustain the fission process. The majority of these fissile isotopes are in the form of 239Pu and 241Pu, although a small portion of 235U can also be present. Because the fast breeder converts die fertile isotope 238 U into the fissile isotope 239Pu, no enrichment plant is necessary. The fast breeder serves as its own enrichment plant. The need for electricity for supplemental uses in the fuel cycle process is thus reduced. Several of the early hquid-metal-cooled fast reactors used plutonium fuels. The reactor Clementine, first operated in the Unired States in 1949. utilized plutonium metal, as did the BR-1 and BR.-2 reactors in the former Soviet Union in 1955 and 1956, respectively. The BR-5 in the former Soviet Union, put into operation in 1959. utilized plutonium oxide and carbide. The reactor Rapsodie first operated in France in 1967 utilized uranium and plutonium oxides. 

The worst nuclear accident was occurred in Chernobyl nuclear reactor near Kiev Soviet Union and caused nearly 30,000 cancer-related deaths over a 50 year period.. ... 

Russia turned up at Geneva that same year of 1955 with more than hollow promises. Alongside our full-scale 4 swimming-poor nuclear reactor which we had flown to the Conference for exhibition, the young Russian scientists presented a model of her first "commercial power reactor which, they said, had been in operation for more than a year. Not far from Moscow it had fed 5000 kilowatts of electrical energy into farms, factories and homes on a modest experimental scale. The new Soviet Five Year Plan calls for the completion by 1960 of several atomic energy plants with a total capacity equal to that of the United States and England combined. These are to be built mainly in the European part of the Soviet Union where coal and other fuel are in short supply. 

Actinides in the environment can be classified into two groups (i) the uranium and thorium series of radionuclides in the natural environment and (ii) neptunium, plutonium, americium and curium which are formed in a nuclear reactor during the neutron bombardment of uranium through a series of neutron capture and radioactive decay reactions. Transuranics thus produced have been spread widely in the atmosphere, geosphere and aquatic environment on the earth, as a result of nuclear bomb tests in the atmosphere, and accidental release from nuclear facilities (Sakanoue, 1987). Most of these radionuclide inventories have deposited in the northern hemisphere following the tests conducted by the United States and the Soviet Union. 

On 26 April 1986 at 0123 hours local time an accident occurred at the fourth unit of the Chernobyl nuclear power station. The accident destroyed the reactor core and part of the building in which the core was housed. The radioactive materials released were carried away in the form of gases and dust particles by air currents. In this manner, they were widely dispersed over the territory of the Soviet Union, over many other (mostly European) countries and, in trace amounts, throughout the northern hemisphere. 

The risks associated with the operation of nuclear reactors are small but not negligible, as the failnre of the Three Mile Island reactor in the United States in 1979 and the disaster at Chernobyl in the former Soviet Union in 1987 demonstrated. If a reactor has to be shnt down quickly, there is danger of a meltdown, in which the heat from the continning fission processes melts the uranium fuel. Coolant mnst be circulated until heat from the decay of short-lived isotopes has... 

On April 26, 1986, one of four nuclear reactors exploded more at the Chernobyl power station in Ukraine, a country that used to be a part of the old Soviet Union. The explosion burned for nine days, proving to be the worst nuclear accident in history. The disaster released at least 100 times more radiation than the atom bombs dropped in Nagasaki and Hiroshima. Much of the fallout fell close to Chernobyl,... 

Both the United States and the former Soviet Union have sent nuclear reactors into space to power satellites. However, another giant nuclear reactor was there first—the sun, our local star. In the giant nuclear furnace of a star, nuclei react with one another and release enormous amounts of energy. You count on this energy to warm your air and water and to power your home, calculators, and other devices that run on solar power. Without this energy, life on Earth as you know it would not be possible. Is it possible to copy the reaction that takes place in stars and make a powerful generator that will provide electricity ... 

Both human and mechanical errors led to overheating of the reaction chamber at the Chernobyl nuclear plant in the former Soviet Union in 1986. Water used to cool the chamber decomposed into hydrogen and oxygen gas, which exploded and blew the roof off the building that housed the reactor. A large amount of radioactive debris was released and traveled as far away as Scandinavia and England. Even now, almost 1000 square miles around the plant are considered too radioactive for permanent habitation. 

In 1986, a disastrous accident occurred at the Chernobyl nuclear power plant in the former Soviet Union releasing radiation in the surrounding area. Public opposition to nuclear power grew and in the U.S., 117 nuclear reactors were canceled. These cancellations outnumbered the country s 103 operating reactors. One or two plants came online in the mid-1990s and no others were scheduled. 

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. 

---