Uploaded by 888Quetzalcoatl888 on Mar 14, 2011
So much conflicting information is coming out of Japan that all we can confirm is that Mox Fuel is in reactor #3. At the same time certain news outlets are saying the situation is nearing an end and that radiation in the U.S. is unlikely. YEAH RIGHT....DERRR???
What is Mox fuel and how much stronger is it then normal uranium? According to World Nuclear News, in August 2010 Japan loaded Mox fuel into the Fukushima #3 reactor.
"Tokyo Electric Power Company's (Tepco's) Fukushima I unit 3 is set to become the third Japanese nuclear reactor to load mixed oxide (MOX) fuel after receiving approval from the governor of Fukushima Prefecture, Yukei Sato."
How is Mox fuel different then uranium? The BBC has also confirmed that Mox Fuel has been used in reactor #3!
In the meantime, there have been suggestions that an incident at reactor 3 would inherently be more dangerous than at reactors 1 and 2 because it burns "mixed oxide fuel" (MOX) containing plutonium.
TECHNICAL ASPECTS OF MOX FUEL IN LIGHT WATER
REACTORS (LWR)/ THE REACTOR OPTION
1. How Does It Work? Major Differences From Conventional LWRs
Proponents of burning plutonium in mixed-oxide(MOX) fuel in LWRs often say that since plutonium already exists in the burned
uranium fuel and is still burning, there will not be a big
difference by increasing the amount of plutonium a little bit. The fact is that great effort is put to make it "not a big
difference." In conventional LWRs, the uranium fuel has about 3% fissile uranium-235 and the rest is non-fissile uranium-238. When fissile uranium absorbs a neutron, it starts fissioning and
releases energy, emitting several neutrons. One neutron will likely start another fission, creating a chain reaction, but the other neutrons must be controlled so that it will not make a
massive reaction which will induce an uncontrolled chain
reaction. Control rods are designed to absorb the extra neutrons.
But some neutrons are also absorbed by the non-fissile
uranium-238 and this decays into fissile plutonium-239.
In the beginning, the plutonium content is zero and the fissileuranium is about 3%. The fissile uranium decreases as they burn, creating plutonium at the same time. At the end of one reactor cycle, the content of fissile uranium is about 0.7%-0.8%,
approximately equal to the content of fissile plutonium-239 that is created.(1)
In the case of MOX fuel used in one-third of a LWR core, the plutonium content is roughly 4% from the beginning, which is approximately 5 times more than that in the end of one cycle of a uranium fuel. This is a significant difference in terms of
core nuclear physics.(2)
In a fast reactor, plutonium content of MOX fuel can be up to 50%. In the option to burn plutonium in CANDU reactors, the MOX fuel content could be 100% core.(3) But this has not been
tested, nor is there any experience at all of burning plutonium fuel in CANDU reactors.
All light water reactors are designed to burn uranium fuel.
Thus the nuclear physics of MOX fuels must be adapted to be as similar as possible to that of uranium fuel. The MOX fuel
assemblies should be able to be operated as uranium assemblies without any restriction to the level of power, performance or
safety. Plutonium is produced during nuclear fission, so is present in all reactor cores -- the longer the fuel has been there, the more plutonium will be present, up to about 1%.
In some countries, spent fuel rods are re-processed and the plutonium set to one side.
However, Japan -- in an attempt to be more frugal with a valuable resource -- has a programme that mixes the plutonium coming out of the re-processing facility back into new fuel rods that also contain uranium. This is MOX fuel. The Guardian
Shaun Burnie, an independent nuclear energy consultant and former head of nuclear campaigns at Greenpeace, said the presence of a percentage of fuel core loaded with plutonium Mox fuel in the No 3 reactor posed a grave threat to the surrounding area.
"Plutonium Mox fuel increases the risk of nuclear accident due the neutronic effects of plutonium on the reactor," Burnie told the Guardian. "In the event of an accident -- in particular loss of coolant -- the reactor core is more difficult to control due to both neutronics and higher risk of fuel cladding failure. In the event of the fuel melting and the release of plutonium fuel into the environment, the health hazards are greater, including higher levels of latent cancer."
What is Mox fuel and how much stronger is it then normal uranium? According to World Nuclear News, in August 2010 Japan loaded Mox fuel into the Fukushima #3 reactor.
"Tokyo Electric Power Company's (Tepco's) Fukushima I unit 3 is set to become the third Japanese nuclear reactor to load mixed oxide (MOX) fuel after receiving approval from the governor of Fukushima Prefecture, Yukei Sato."
How is Mox fuel different then uranium? The BBC has also confirmed that Mox Fuel has been used in reactor #3!
In the meantime, there have been suggestions that an incident at reactor 3 would inherently be more dangerous than at reactors 1 and 2 because it burns "mixed oxide fuel" (MOX) containing plutonium.
TECHNICAL ASPECTS OF MOX FUEL IN LIGHT WATER
REACTORS (LWR)/ THE REACTOR OPTION
1. How Does It Work? Major Differences From Conventional LWRs
Proponents of burning plutonium in mixed-oxide(MOX) fuel in LWRs often say that since plutonium already exists in the burned
uranium fuel and is still burning, there will not be a big
difference by increasing the amount of plutonium a little bit. The fact is that great effort is put to make it "not a big
difference." In conventional LWRs, the uranium fuel has about 3% fissile uranium-235 and the rest is non-fissile uranium-238. When fissile uranium absorbs a neutron, it starts fissioning and
releases energy, emitting several neutrons. One neutron will likely start another fission, creating a chain reaction, but the other neutrons must be controlled so that it will not make a
massive reaction which will induce an uncontrolled chain
reaction. Control rods are designed to absorb the extra neutrons.
But some neutrons are also absorbed by the non-fissile
uranium-238 and this decays into fissile plutonium-239.
In the beginning, the plutonium content is zero and the fissileuranium is about 3%. The fissile uranium decreases as they burn, creating plutonium at the same time. At the end of one reactor cycle, the content of fissile uranium is about 0.7%-0.8%,
approximately equal to the content of fissile plutonium-239 that is created.(1)
In the case of MOX fuel used in one-third of a LWR core, the plutonium content is roughly 4% from the beginning, which is approximately 5 times more than that in the end of one cycle of a uranium fuel. This is a significant difference in terms of
core nuclear physics.(2)
In a fast reactor, plutonium content of MOX fuel can be up to 50%. In the option to burn plutonium in CANDU reactors, the MOX fuel content could be 100% core.(3) But this has not been
tested, nor is there any experience at all of burning plutonium fuel in CANDU reactors.
All light water reactors are designed to burn uranium fuel.
Thus the nuclear physics of MOX fuels must be adapted to be as similar as possible to that of uranium fuel. The MOX fuel
assemblies should be able to be operated as uranium assemblies without any restriction to the level of power, performance or
safety. Plutonium is produced during nuclear fission, so is present in all reactor cores -- the longer the fuel has been there, the more plutonium will be present, up to about 1%.
In some countries, spent fuel rods are re-processed and the plutonium set to one side.
However, Japan -- in an attempt to be more frugal with a valuable resource -- has a programme that mixes the plutonium coming out of the re-processing facility back into new fuel rods that also contain uranium. This is MOX fuel. The Guardian
Shaun Burnie, an independent nuclear energy consultant and former head of nuclear campaigns at Greenpeace, said the presence of a percentage of fuel core loaded with plutonium Mox fuel in the No 3 reactor posed a grave threat to the surrounding area.
"Plutonium Mox fuel increases the risk of nuclear accident due the neutronic effects of plutonium on the reactor," Burnie told the Guardian. "In the event of an accident -- in particular loss of coolant -- the reactor core is more difficult to control due to both neutronics and higher risk of fuel cladding failure. In the event of the fuel melting and the release of plutonium fuel into the environment, the health hazards are greater, including higher levels of latent cancer."
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