Fukushima I and II
Among the radioactive materials found at nuclear power plants you will find enriched uranium, low-level waste, and spent nuclear fuel.
Enriched uranium, in the form of a pellet roughly one-inch-long, serves as the fuel for nuclear power plants; there may be over 100 tons of fuel pellets present in a single reactor. One pellet can generate approximately the same amount of electricity as one ton of coal. Uranium fuel is only mildly radioactive and can be handled safely without shielding, unlike spent fuel, which is extremely radioactive.
Low-level radioactive waste includes items that have become contaminated with radioactive material. This waste typically consists of contaminated protective shoe covers and clothing, wiping rags, mops, filters, reactor water treatment residues, and equipment and tools. Low-level waste is stored at the nuclear power plant until either the radioactivity in the waste decays away, allowing it to be disposed of as ordinary trash, or there is enough waste for shipment to a low-level waste disposal site.
Spent nuclear fuel includes many highly radioactive byproducts of the fission process. The fuel is stored at the nuclear power plant site in specially designed pools resembling large swimming pools or in specially designed dry storage containers. In the pools the water cools the fuel and acts as a radiation shield. The storage containers can also cool the fuel and contain the radiation emitted by the used fuel.
Local and state governments, federal agencies, and the electric utilities have emergency response plans in the event of a nuclear power plant incident. The plans define two “emergency planning zones.” One zone covers an area within a 10-mile radius of the plant, where it is possible that people could be harmed by direct radiation exposure. The second zone covers a broader area, usually up to a 50-mile radius from the plant, where radioactive materials could contaminate water supplies, food crops, and livestock.
The potential danger from an accident at a nuclear power plant is exposure to radiation. This exposure could come from the release of radioactive material from the plant into the environment, usually characterized by a plume (cloud-like formation) of radioactive gases and particles. The major hazards to people in the vicinity of the plume are radiation exposure to the body from the cloud and particles deposited on the ground, inhalation of radioactive materials, and ingestion of radioactive materials.
High-level radioactive wastes are the highly radioactive materials produced as a byproduct of the reactions that occur inside nuclear reactors. High-level wastes take one of two forms:
• Spent (used) reactor fuel when it is accepted for disposal
• Waste materials remaining after spent fuel is reprocessed
Spent nuclear fuel is used fuel from a reactor that is no longer efficient in creating electricity, because its fission process has slowed. However, it is still thermally hot, highly radioactive, and potentially harmful. Until a permanent disposal repository for spent nuclear fuel is built, licensees must safely store this fuel at their reactors.
Spent Fuel Pools
The water-pool option involves storing spent fuel rods under at least 20 feet of water, which provides adequate shielding from the radiation for anyone near the pool. The rods are moved into the water pools from the reactor along the bottom of water canals, so that the spent fuel is always shielded to protect workers.
About one-fourth to one-third of the total fuel load from the pools is spent and removed from the reactor every 12 to 18 months and replaced with fresh fuel.
Life cycle
The nuclear fuel cycle begins when uranium is mined, enriched, and manufactured into nuclear fuel, (1) which is delivered to a nuclear power plant. After usage in the power plant, the spent fuel is delivered to a reprocessing plant (2) or to a final repository (3) for geological disposition. In reprocessing 95% of spent fuel can be recycled to be returned to usage in a power plant (4).Main article: Nuclear fuel cycle
A nuclear reactor is only part of the life-cycle for nuclear power. The process starts with mining (see Uranium mining). Uranium mines are underground, open-pit, or in-situ leach mines. In any case, the uranium ore is extracted, usually converted into a stable and compact form such as yellowcake, and then transported to a processing facility. Here, the yellowcake is converted to uranium hexafluoride, which is then enriched using various techniques. At this point, the enriched uranium, containing more than the natural 0.7% U-235, is used to make rods of the proper composition and geometry for the particular reactor that the fuel is destined for. The fuel rods will spend about 3 operational cycles (typically 6 years total now) inside the reactor, generally until about 3% of their uranium has been fissioned, then they will be moved to a spent fuel pool where the short lived isotopes generated by fission can decay away. After about 5 years in a spent fuel pool the spent fuel is radioactively and thermally cool enough to handle and it can be moved to dry storage casks or reprocessed.
High-level radioactive waste
After about 5% of a nuclear fuel rod has reacted inside a nuclear reactor that rod is no longer able to be used as fuel (due to the build-up of fission products). Today, scientists are experimenting on how to recycle these rods so as to reduce waste and use the remaining actinides as fuel (large-scale reprocessing is being used in a number of countries).
A typical 1000-MWe nuclear reactor produces approximately 20 cubic meters (about 27 tonnes) of spent nuclear fuel each year (but only 3 cubic meters of vitrified volume if reprocessed).[82][83] All the spent fuel produced to date by all commercial nuclear power plants in the US would cover a football field to the depth of about one meter.[84]
Spent nuclear fuel is initially very highly radioactive and so must be handled with great care and forethought. However, it will decrease with time. After 40 years, the radiation flux is 99.9% lower than it was the moment the spent fuel was removed from operation. Still, this 0,1% is dangerously radioactive.[76] After 10,000 years of radioactive decay, according to United States Environmental Protection Agency standards, the spent nuclear fuel will no longer pose a threat to public health and safety.[citation needed]
When first extracted, spent fuel rods are stored in shielded basins of water (spent fuel pools), usually located on-site. The water provides both cooling for the still-decaying fission products, and shielding from the continuing radioactivity. After a period of time (generally five years for US plants), the now cooler, less radioactive fuel is typically moved to a dry-storage facility or dry cask storage, where the fuel is stored in steel and concrete containers. Most U.S. waste is currently stored at the nuclear site where it is generated, while suitable permanent disposal methods are discussed.
Fukushima Dai-ichi (dai-ichi means "number one"), is a disabled nuclear power plant located on a 3,500,000-square-metre (860-acre) site[1] in the towns of Okuma and Futaba in the Futaba District of Fukushima Prefecture, Japan. First commissioned in 1971, the plant consists of six boiling water reactors (BWR). These light water reactors[2] drove electrical generators with a combined power of 4.7 GWe, making Fukushima I one of the 15 largest nuclear power stations in the world.
Reactor data
Unit Type[17]
First criticality[18]
Electric power (MW)
Since Criticality (years) Annual Waste (tonnes) Waste Since Criticality
Fukushima I – 1 BWR-3
10-Oct-70 460 3/11/2011 40.44 12.42 502.31
Fukushima I – 2 BWR-4 10-May-73 784 3/11/2011 37.86 21.17 801.43
Fukushima I – 3 BWR-4 6-Sep-74 784 3/11/2011 36.53 21.17 773.36
Fukushima I – 4 BWR-4 28-Jan-78 784 3/11/2011 33.14 21.17 701.44
Fukushima I – 5 BWR-4 26-Aug-77 784 3/11/2011 33.56 21.17 710.43
Fukushima I – 6 BWR-5 9-Mar-79 1,100 3/11/2011 32.03 29.70 951.21
Complex total 4696 MW 4440.19
Fukushima Dai-ni (dai-ni means "number two"), is a nuclear power plant located on a 1,500,000-square-metre (370-acre) site[1] in the town of Naraha and Tomioka in the Futaba District of Fukushima Prefecture, Japan. The Tokyo Electric Power Company (TEPCO) runs the plant. All reactors in the Fukushima II Nuclear Power Plant are BWR-5 type[3] with electric power of 1,100 MW each (net output: 1,067 MW each).
Unit Type[17]
First criticality[18]
Electric power (MW)
Since Criticality (years) Annual Waste (tonnes) Waste Since Criticality
Fukushima II – 1 BWR-5 31-Jul-81 1,100 3/11/2011 29.63 29.70 880.02
Fukushima II – 2 BWR-5 23-Jun-83 1,100 3/11/2011 27.73 29.70 823.71
Fukushima II – 3 BWR-5 14-Dec-84 1,100 3/11/2011 26.25 29.70 779.77
Fukushima II – 4 BWR-5 17-Dec-86 1,100 3/11/2011 24.25 29.70 720.12
3203.61
Fukushima 1’s estimated nuclear waste equates to 4.4 kilotons of material and Fukushima 2 equates to 3.2 kilotons.
Hiroshima and Nagasaki
Hiroshima became the target of the first weapon at 08.15 on 6 August 1945. The all-clear had in fact sounded from an initial alert when the bomb was dropped. It was carried by a B-29 Superfortress called Enola Gay, and exploded about 602 yards (550 meters) over the city producing the equivalent of 15 kilotons of energy. Eyewitnesses reported seeing a parachute falling followed by a blast of intense heat. Between 130, 000 and 200, 000 people died, were injured, or disappeared. The Japanese government attempted to play down the impact and significance of this ominous development, which was followed a few days later by a second atomic bombing. This weapon had been destined for Kokura on the southern Japanese island of Kyushu, but cloud cover forced the crew to attack their secondary target of the shipyards of Nagasaki. The Nagasaki bomb was of about 20 kilotons but did less damage because of the local topography. It exploded above Urakami to the north of the port.
Read more: http://www.answers.com/topic/bombings-of-hiroshima-and-nagasaki#ixzz1IT948I3P
Yield (megatons) .0044 (4.4 kilotons)
Calculated Values
Thermal radiation radius (3rd degree burns) 1.3 kilometres
Air blast radius (widespread destruction) 1.2 kilometres
Air blast radius (near-total fatalities) 457 metres
Ionizing radiation radius (500 rem) 1.1 kilometres
Fireball duration
Fireball radius (minimum) 50 metres
Fireball radius (airburst) 60 metres
Fireball radius (ground-contact airburst) 80 metres
Enriched uranium, in the form of a pellet roughly one-inch-long, serves as the fuel for nuclear power plants; there may be over 100 tons of fuel pellets present in a single reactor. One pellet can generate approximately the same amount of electricity as one ton of coal. Uranium fuel is only mildly radioactive and can be handled safely without shielding, unlike spent fuel, which is extremely radioactive.
Low-level radioactive waste includes items that have become contaminated with radioactive material. This waste typically consists of contaminated protective shoe covers and clothing, wiping rags, mops, filters, reactor water treatment residues, and equipment and tools. Low-level waste is stored at the nuclear power plant until either the radioactivity in the waste decays away, allowing it to be disposed of as ordinary trash, or there is enough waste for shipment to a low-level waste disposal site.
Spent nuclear fuel includes many highly radioactive byproducts of the fission process. The fuel is stored at the nuclear power plant site in specially designed pools resembling large swimming pools or in specially designed dry storage containers. In the pools the water cools the fuel and acts as a radiation shield. The storage containers can also cool the fuel and contain the radiation emitted by the used fuel.
Local and state governments, federal agencies, and the electric utilities have emergency response plans in the event of a nuclear power plant incident. The plans define two “emergency planning zones.” One zone covers an area within a 10-mile radius of the plant, where it is possible that people could be harmed by direct radiation exposure. The second zone covers a broader area, usually up to a 50-mile radius from the plant, where radioactive materials could contaminate water supplies, food crops, and livestock.
The potential danger from an accident at a nuclear power plant is exposure to radiation. This exposure could come from the release of radioactive material from the plant into the environment, usually characterized by a plume (cloud-like formation) of radioactive gases and particles. The major hazards to people in the vicinity of the plume are radiation exposure to the body from the cloud and particles deposited on the ground, inhalation of radioactive materials, and ingestion of radioactive materials.
High-level radioactive wastes are the highly radioactive materials produced as a byproduct of the reactions that occur inside nuclear reactors. High-level wastes take one of two forms:
• Spent (used) reactor fuel when it is accepted for disposal
• Waste materials remaining after spent fuel is reprocessed
Spent nuclear fuel is used fuel from a reactor that is no longer efficient in creating electricity, because its fission process has slowed. However, it is still thermally hot, highly radioactive, and potentially harmful. Until a permanent disposal repository for spent nuclear fuel is built, licensees must safely store this fuel at their reactors.
Spent Fuel Pools
The water-pool option involves storing spent fuel rods under at least 20 feet of water, which provides adequate shielding from the radiation for anyone near the pool. The rods are moved into the water pools from the reactor along the bottom of water canals, so that the spent fuel is always shielded to protect workers.
About one-fourth to one-third of the total fuel load from the pools is spent and removed from the reactor every 12 to 18 months and replaced with fresh fuel.
Life cycle
The nuclear fuel cycle begins when uranium is mined, enriched, and manufactured into nuclear fuel, (1) which is delivered to a nuclear power plant. After usage in the power plant, the spent fuel is delivered to a reprocessing plant (2) or to a final repository (3) for geological disposition. In reprocessing 95% of spent fuel can be recycled to be returned to usage in a power plant (4).Main article: Nuclear fuel cycle
A nuclear reactor is only part of the life-cycle for nuclear power. The process starts with mining (see Uranium mining). Uranium mines are underground, open-pit, or in-situ leach mines. In any case, the uranium ore is extracted, usually converted into a stable and compact form such as yellowcake, and then transported to a processing facility. Here, the yellowcake is converted to uranium hexafluoride, which is then enriched using various techniques. At this point, the enriched uranium, containing more than the natural 0.7% U-235, is used to make rods of the proper composition and geometry for the particular reactor that the fuel is destined for. The fuel rods will spend about 3 operational cycles (typically 6 years total now) inside the reactor, generally until about 3% of their uranium has been fissioned, then they will be moved to a spent fuel pool where the short lived isotopes generated by fission can decay away. After about 5 years in a spent fuel pool the spent fuel is radioactively and thermally cool enough to handle and it can be moved to dry storage casks or reprocessed.
High-level radioactive waste
After about 5% of a nuclear fuel rod has reacted inside a nuclear reactor that rod is no longer able to be used as fuel (due to the build-up of fission products). Today, scientists are experimenting on how to recycle these rods so as to reduce waste and use the remaining actinides as fuel (large-scale reprocessing is being used in a number of countries).
A typical 1000-MWe nuclear reactor produces approximately 20 cubic meters (about 27 tonnes) of spent nuclear fuel each year (but only 3 cubic meters of vitrified volume if reprocessed).[82][83] All the spent fuel produced to date by all commercial nuclear power plants in the US would cover a football field to the depth of about one meter.[84]
Spent nuclear fuel is initially very highly radioactive and so must be handled with great care and forethought. However, it will decrease with time. After 40 years, the radiation flux is 99.9% lower than it was the moment the spent fuel was removed from operation. Still, this 0,1% is dangerously radioactive.[76] After 10,000 years of radioactive decay, according to United States Environmental Protection Agency standards, the spent nuclear fuel will no longer pose a threat to public health and safety.[citation needed]
When first extracted, spent fuel rods are stored in shielded basins of water (spent fuel pools), usually located on-site. The water provides both cooling for the still-decaying fission products, and shielding from the continuing radioactivity. After a period of time (generally five years for US plants), the now cooler, less radioactive fuel is typically moved to a dry-storage facility or dry cask storage, where the fuel is stored in steel and concrete containers. Most U.S. waste is currently stored at the nuclear site where it is generated, while suitable permanent disposal methods are discussed.
Fukushima Dai-ichi (dai-ichi means "number one"), is a disabled nuclear power plant located on a 3,500,000-square-metre (860-acre) site[1] in the towns of Okuma and Futaba in the Futaba District of Fukushima Prefecture, Japan. First commissioned in 1971, the plant consists of six boiling water reactors (BWR). These light water reactors[2] drove electrical generators with a combined power of 4.7 GWe, making Fukushima I one of the 15 largest nuclear power stations in the world.
Reactor data
Unit Type[17]
First criticality[18]
Electric power (MW)
Since Criticality (years) Annual Waste (tonnes) Waste Since Criticality
Fukushima I – 1 BWR-3
10-Oct-70 460 3/11/2011 40.44 12.42 502.31
Fukushima I – 2 BWR-4 10-May-73 784 3/11/2011 37.86 21.17 801.43
Fukushima I – 3 BWR-4 6-Sep-74 784 3/11/2011 36.53 21.17 773.36
Fukushima I – 4 BWR-4 28-Jan-78 784 3/11/2011 33.14 21.17 701.44
Fukushima I – 5 BWR-4 26-Aug-77 784 3/11/2011 33.56 21.17 710.43
Fukushima I – 6 BWR-5 9-Mar-79 1,100 3/11/2011 32.03 29.70 951.21
Complex total 4696 MW 4440.19
Fukushima Dai-ni (dai-ni means "number two"), is a nuclear power plant located on a 1,500,000-square-metre (370-acre) site[1] in the town of Naraha and Tomioka in the Futaba District of Fukushima Prefecture, Japan. The Tokyo Electric Power Company (TEPCO) runs the plant. All reactors in the Fukushima II Nuclear Power Plant are BWR-5 type[3] with electric power of 1,100 MW each (net output: 1,067 MW each).
Unit Type[17]
First criticality[18]
Electric power (MW)
Since Criticality (years) Annual Waste (tonnes) Waste Since Criticality
Fukushima II – 1 BWR-5 31-Jul-81 1,100 3/11/2011 29.63 29.70 880.02
Fukushima II – 2 BWR-5 23-Jun-83 1,100 3/11/2011 27.73 29.70 823.71
Fukushima II – 3 BWR-5 14-Dec-84 1,100 3/11/2011 26.25 29.70 779.77
Fukushima II – 4 BWR-5 17-Dec-86 1,100 3/11/2011 24.25 29.70 720.12
3203.61
Fukushima 1’s estimated nuclear waste equates to 4.4 kilotons of material and Fukushima 2 equates to 3.2 kilotons.
Hiroshima and Nagasaki
Hiroshima became the target of the first weapon at 08.15 on 6 August 1945. The all-clear had in fact sounded from an initial alert when the bomb was dropped. It was carried by a B-29 Superfortress called Enola Gay, and exploded about 602 yards (550 meters) over the city producing the equivalent of 15 kilotons of energy. Eyewitnesses reported seeing a parachute falling followed by a blast of intense heat. Between 130, 000 and 200, 000 people died, were injured, or disappeared. The Japanese government attempted to play down the impact and significance of this ominous development, which was followed a few days later by a second atomic bombing. This weapon had been destined for Kokura on the southern Japanese island of Kyushu, but cloud cover forced the crew to attack their secondary target of the shipyards of Nagasaki. The Nagasaki bomb was of about 20 kilotons but did less damage because of the local topography. It exploded above Urakami to the north of the port.
Read more: http://www.answers.com/topic/bombings-of-hiroshima-and-nagasaki#ixzz1IT948I3P
Yield (megatons) .0044 (4.4 kilotons)
Calculated Values
Thermal radiation radius (3rd degree burns) 1.3 kilometres
Air blast radius (widespread destruction) 1.2 kilometres
Air blast radius (near-total fatalities) 457 metres
Ionizing radiation radius (500 rem) 1.1 kilometres
Fireball duration
Fireball radius (minimum) 50 metres
Fireball radius (airburst) 60 metres
Fireball radius (ground-contact airburst) 80 metres
posted by Silver Eagle | 7:27 AM
0 Comments:
Post a Comment
<< Home