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The advantage of heavy water as coolant over light water in pressurized reactors?
In the CANDU reactor heavy water is used as the moderator. It is a much better moderator than light water because it does not absorb neutrons so strongly, and enables non-enriched uranium to be used. The heavy water moderator is enclosed in a tank with fuel channel tubes, called technically a calandria. The coolant is also heavy water which flows through the tubes and hence past the fuel elements, and then transfers its heat to a light water secondary circuit. In a PWR or BWR light water is used both as moderator and coolant, which is obviously much cheaper and less complicated, but does require uranium enriched in U-235.
Why is heavy water used for heat transfer in nuclear reactor?
Heavy water has the same heat transfer properties as ordinary water, at least in practical terms. It is used in some reactors as the moderator since it is much more efficient at slowing fast neutrons than ordinary water, thus enabling unenriched uranium to be used as the fuel. It is not used to transfer heat to the power producing part of the plant, only as a static tank (called a calandria) full of heavy water as moderator. (See CANDU)
How is fuel in a nuclear reactor obtained?
It is either mined or synthesized, though usually mined, as this is much less expensive. Some reactors (such as the CANDU) can even use the waste from other reactors, without any refinement at all.
Why do American nuclear plants use light water instead of heavy water in the reactors?
Mainly I believe because the light water PWR was developed for submarines and as compact a reactor as possible was required. Since then of course it (and BWR's) have been up-sized very successfully. Enriched fuel can now be made much more easily and cheaply by centrifuges than by the diffusion method, so to obtain low enriched fuel is more economical. There is also MOX available, though I don't think the US uses this. See the discussion page as well
How does a heavy water nuclear reactor work?
Uranium and Plutonium atoms require nuetrons moving at a certain speed, with a certain amount of kenetic force, to fission properly and often, and to achieve this speed, a neutron moderator is placed between the neutron source and the fuel, which slows the neutrons down by causing them to hit its molecules. Water is often used, since the energy transfer is much more efficient, as hydrogen atoms are almost identical in size to neutrons, possesing only one proton (like two billiard balls striking each other), but hydrogen atoms sometimes absorb neutrons, meaning less get through to cause fissions, and once the concentration of fissionable material drops blow a certain percentage (usualy somewhere around 5%) fission is no longer maintainable. Heavy water posses hydrogen atoms with one extra neutron, so althought the energy transfer is slightly less efficient than with hydrogen atoms, there is much less chance of the atoms abosorbing neutrons, and so many more neutrons get through, allowing the reactor to run on fuel with much lower concetrations of fisionable material (even as low as 0.7%, the natural level of U-235 in Uranium ore). Thus somereacotrs using heavy warer as a neutron moderator (such as the CANDU) can even run on the waste from other, "light water moderated" reactors (light water is just another name for normal water, as opposed to heavy water).
Why Pressurized Water Reactor nuclear reactor is the most commonly used reactor?
I guess because it is the one with the fewest operational problems and the longest operational life. BWR's introduce the problems of a contaminated turbine. Gas cooled graphite reactors are efficient but there are life limitations on the graphite. Heavy water reactors have the benefit of using natural uranium but the heavy water is very expensive to produce. So the choice is between enriching uranium as for the PWR, or producing heavy water as for the CANDU. Most countries are now opting the PWR way as enriching uranium by centrifuge has become much less expensive than the old gaseous diffusion method.
The advantage of heavy water as coolant over light water in pressurized reactors?
In the CANDU reactor heavy water is used as the moderator. It is a much better moderator than light water because it does not absorb neutrons so strongly, and enables non-enriched uranium to be used. The heavy water moderator is enclosed in a tank with fuel channel tubes, called technically a calandria. The coolant is also heavy water which flows through the tubes and hence past the fuel elements, and then transfers its heat to a light water secondary circuit. In a PWR or BWR light water is used both as moderator and coolant, which is obviously much cheaper and less complicated, but does require uranium enriched in U-235.
How much uranium 235 is used in a nuclear reactor?
Depending on the type and the power of the nuclear reactor. An example; a CANDU type reactor of 700 MW need 700 kg uranium-235 and only ca. 500 kg are "burned".
Why is heavy water used for heat transfer in nuclear reactor?
Heavy water has the same heat transfer properties as ordinary water, at least in practical terms. It is used in some reactors as the moderator since it is much more efficient at slowing fast neutrons than ordinary water, thus enabling unenriched uranium to be used as the fuel. It is not used to transfer heat to the power producing part of the plant, only as a static tank (called a calandria) full of heavy water as moderator. (See CANDU)
How is fuel in a nuclear reactor obtained?
It is either mined or synthesized, though usually mined, as this is much less expensive. Some reactors (such as the CANDU) can even use the waste from other reactors, without any refinement at all.
What are two types of reactors used in the US?
There are amny different types of reactors but the most commonly used ones are: PWR-Pressurized Water Reactor, this works by pressurizing the reactor allowing the water to boil at a much higher temperature allowing efficentcy to be higher. BWR-Boiling Water Reactor,this is the most basic type of reactor this reactor just boils water that turns turbines and produces electricity, however water levels and temperature have to be constantly monitored, otherwise a reactor could slip into a dangerous state. AGR-Advanced Gas Reactor, this reactor instead of being cooled by water it is instead cooled by pressurized carbon dioxide. FBR-Fast Breeder Reactor, this reactor instead of limiting fast neutrons to occur it allows fast neutrons in the reactor and in the act of doing it produces nuclear fuel that can be used to fuel the reactor.
How much plutonium is needed to run a reactor?
This depends on the type and power of the reactor; say tens of metric tons for a commercial reactor..
Why do American nuclear plants use light water instead of heavy water in the reactors?
Mainly I believe because the light water PWR was developed for submarines and as compact a reactor as possible was required. Since then of course it (and BWR's) have been up-sized very successfully. Enriched fuel can now be made much more easily and cheaply by centrifuges than by the diffusion method, so to obtain low enriched fuel is more economical. There is also MOX available, though I don't think the US uses this. See the discussion page as well
How much energy is lost during nuclear power producttion?
The efficiency of a PWR or BWR reactor power plant is about 33 percent, so this means that about 67 percent of the reactor's thermal output is rejected to the cooling water
What is the function of graphite in the first atomic reactor?
The graphite acts as a moderator, to slow neutrons down. Most fission reactors work on the basis of slow or thermalised neutrons, though some have been built using fast neutrons. When the neutrons are ejected from the uranium nucleus as it fissions or splits, they come off at high speed, but in order to be captured by another nucleus of U-235 they need to be slowed down. This is simply a physical fact, U-235 captures slow neutrons much more readily than it does fast neutrons. Graphite was used in the first demonstration reactor in 1942 and in subsequent bigger reactors at Hanford Wa. It had to be made specially with very high purity to avoid absorbing too many neutrons. Other moderators used are heavy water, as in CANDU reactors, and light water as in PWR. Light water absorbs more neutrons so the fuel has to be enriched in U-235.
How does a heavy water nuclear reactor work?
Uranium and Plutonium atoms require nuetrons moving at a certain speed, with a certain amount of kenetic force, to fission properly and often, and to achieve this speed, a neutron moderator is placed between the neutron source and the fuel, which slows the neutrons down by causing them to hit its molecules. Water is often used, since the energy transfer is much more efficient, as hydrogen atoms are almost identical in size to neutrons, possesing only one proton (like two billiard balls striking each other), but hydrogen atoms sometimes absorb neutrons, meaning less get through to cause fissions, and once the concentration of fissionable material drops blow a certain percentage (usualy somewhere around 5%) fission is no longer maintainable. Heavy water posses hydrogen atoms with one extra neutron, so althought the energy transfer is slightly less efficient than with hydrogen atoms, there is much less chance of the atoms abosorbing neutrons, and so many more neutrons get through, allowing the reactor to run on fuel with much lower concetrations of fisionable material (even as low as 0.7%, the natural level of U-235 in Uranium ore). Thus somereacotrs using heavy warer as a neutron moderator (such as the CANDU) can even run on the waste from other, "light water moderated" reactors (light water is just another name for normal water, as opposed to heavy water).
How much does a fusion reactor cost?
Nobody knows- they have not yet built a fully working fusion reactor.
