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Why is moderator not required in modern fast reactors?
AbhilashKashyap
a moderator would slow the neutrons, hindering breeding
Wiki User
∙ 11y ago
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Why moderator is not used in case of fast breeder reactor?
Moderator is not used in case of fast breeder reactor because there is no need to slow down neutron energy. Nuclear fission takes place at high energy of neutrons.
Why is the moderator important in a nuclear reactor?
The moderator is used to slow down the neutrons present in the core of the reactor. Normally the neutrons produced as the nuclear fuel (e.g. uranium) is fissioned are travelling too fast to produce a sustained chain reaction. Some examples of moderators are cadmium, heavy water and graphite.
Is moderation of neutrons always used to slow nuclear fission?
No, moderation of neutrons is not always used to slow nuclear fission. In some types of nuclear reactors, such as fast breeder reactors, fast neutrons are intentionally not moderated to slow down the fission process. These reactors operate using fast neutrons to sustain a chain reaction. However, in most commercial nuclear reactors, moderation of neutrons is employed to slow down the fission process and maintain a controlled chain reaction.
A moderator is used in nuclear reactor in order to?
The moderator is there to slow down the neutrons produced by fission. These are produced with high energy, that is they move fast, but Uranium235 has a capture cross section much greater for slow neutrons, so they need to be slowed down to make the chain reaction more efficient. Graphite and heavy water are good moderators, and don't absorb too many neutrons, so they can be used even with natural (non-enriched) uranium. Normal water is not so good but it is ok if the uranium is enriched to about 4 percent U235.
Different kinds of powerplant?
The main types of nuclear power plant in use in the world, and exclusively in the US are PWR (Pressurised Water Reactor) and BWR (Boiling Water Reactor) types. These use normal water as moderator and enriched uranium fuel. In Canada a heavy water moderated type of reactor has been successfully used and exported to several countries. In the UK gas cooled reactors have mainly been used, firstly the magnox type and latterly the AGR. Both use carbon dioxide cooling and graphite moderator. In Russia the RBMK type was developed which combined graphite moderating with water cooling. This type has been largely discontinued after Chernobyl. High temperature helium cooled reactors and fast reactors liquid metal cooled have been tried as prototypes but not commercially.
Why moderator is not required in fast reactors?
a moderator would slow the neutrons, hindering breeding
Does a breeder nuclear reactor use moderator?
Thermal Breeder Reactors use moderators but Fast Breeder Reactors don't use moderator.
Can a reactor without moderator is present?
Yes, they are fast nuclear reactors
Are there more fast breeder or thermal nuclear reactors?
Most nuclear reactors are thermal-neutron reactors. A few fast breeder reactors have been built, but not many.
What is a moderator when it concerns nuclear energy?
A moderator is a material that slows fast neutrons.
How much temperature can be controlled by liquid sodium in nuclear reactors?
Liquid sodium has been used as a coolant in fast reactors, because it does not slow down and absorb fast neutrons. It does not control the nuclear reaction directly, for that variable neutron absorbers are required.
What is the moderator in US nuclear power plants?
Neutrons released from the fissioning, or splitting, of Uranium or Plutonium atoms collide with the molecules of the moderator, losing some of their energy in the process. This slows the neutrons down (slow neutrons are referred to as "thermal" neutrons") so that they are more likely to cause fission when colliding with another Uranium or Plutonium atom. In the most common types of reactors the moderator used is ordinary distilled water which is also used as the coolant for the reactor. Graphite and heavy water can also be used, and there are types of reactors which use no moderator at all - they operate on "fast" neutrons alone.
What has the author Karl Wirtz written?
Karl Wirtz has written: 'Lectures on fast reactors' -- subject(s): Fast reactors
What is the coolant used in kalpakkam power station in India?
Kalpakkam has both Thermal reactor (Madras Atomic Power Station) and Fast Breeder Reactor -FBTR and PFBR (Under construction). In MAPS (thermal reactor) it is Heavy Water (D2O) Which acts as a coolant as well as moderator, where as in Fast Breeder Test Reactor (FBTR) and Prototype Fast Breeder Reactor (PFBR) Sodium (Na) is used as coolant. Since there should not any moderators for fast reactors D2O will not be used as coolant in fast reactors.
Is power reactor a thermal reactor?
All power reactors are thermal reactors except few ones that are fast nuclear reactors.
What metal do power stations use as a liquid cooler?
Most current nuclear power plants just use ordinary wateras coolant.However experimental reactors have been built using:MercuryNaK - Sodium Potassium alloyLeadSolder - Tin Lead alloyOil (which also acts as moderator to slow neutrons)etc.NaK was the most common in fast breeder power reactors.
What is the pecentage of Uranium-235 in fuel rods?
In new rods it is generally between 4 and 5 percent (this is for PWR and BWR) In new rods it is generally between 20 and 90 percent (this is for breeder reactors and other liquid metal cooled unmoderated fast reactors). Yes, this is in the weapons grade range, but that's what you need to get a fission chain reaction without moderator.
