The steam is used to drive the turbines which produce electricity (as in most fossil fuel plants). Comment * Related Questions on Power Plant Engineering. Infact there is a range of energy within which they can cause fission. As you must have understood above, a moderator is a medium which is used to absorb a portion of the kinetic energy of fast neutrons so that they come in the category of thermal neutrons which help to sustain a controlled chain reaction. 2. Reactors for propulsion applications use. D. Cause collision with the fast moving neutrons to reduce their speed. The principles for using nuclear power to produce electricity are the same for most types of reactor. Which element is used as moderator in nuclear reactor? PLEASE COMMENT BELOW WITH CORRECT ANSWER AND ITS DETAIL EXPLANATION. Accelerate the neutrons Water as a moderator. A. Existing nuclear power plants use mature technologies with a long experience of domestic expertise in operations, oversight, and regulation. B. C. Any form of uranium. Moderator in nuclear plants is used to. A nuclear reactor is a system used to initiate and contain a nuclear chain reaction, and they have many useful applications.These nuclear reactions produce thermal energy through either nuclear fission (in practice) or nuclear fusion (in development). A moderator slows down the neutrons, because slower moving neutrons are better at causing fission to occur. The problem lies in the fact that whenever a thermal neutron causes fission it also leads to the release of fast neutrons. The Nuclear Fuel Cycle Describes the Entire Process of Burning Fuel in the Shape of Nuclear Fuel Rods, Reflector Material in a Nuclear Power Plant Reflects Neutrons Back Into the Core Reactor To Prevent Escaped Energy. The only flipside of using light-water is that the fuel has to be enriched to use with water, Deuterium - also known as heavy water in common terminology, Deuterium is costly to manufacture as compared to light water but gives the option of using un-enriched fuel in the reactor which is a big advantage, Miscellaneous - Several materials such as Graphite, Beryllium, Lithium are used in different types of reactors as moderators. Radioactivity tracers are commonly used in the medical field and also in the study of plants and animals. In nuclear fission, atoms are split apart to form smaller atoms, releasing energy. Often, the liquid serves as a coolant, which is also a moderator. Answer: Option D . The main function of the moderator in a nuclear reactor is to slow down the neutrons from high energy levels as well as high velocities. C. Graphite and air. This makes the target unstable and makes it split into two parts accompanied with the release of energy which is utilized to generate electricity. C. Control the reaction. These neutrons fly randomly in all directions and are usually in the region of fast moving energy neutrons. A moderator is usually water; however, graphite and heavy water can also be used. A moderator is used in nuclear reactor in order to ? Ans: d. 8. The Experimental Breeder Reactor I (EBR-I) outside of Arco, Idaho had used nuclear … Here are some of the important components of the Nuclear Power Plants. © Copyright 2016-2020 - www.PakMcqs.com/. Nuclear power plants use heat produced during nuclear fission to heat water. Now these fast neutrons have to be slowed down and brought to lower energy levels if they have to cause successful fission in turn. B. It uses a graphite moderator and standard assay low-enriched uranium fuel with the same level of enrichment (less than 5% U-235) as in conventional nuclear plants. The heat from the reactor creates steam, which runs through turbines to power electrical generators. Just to give you a relative idea a fast moving neutron travels with a speed which is nearly in the region of 10% of the speed of light, while a thermal neutron travels with a speed which is typically of the order of a few kilometers per second. The function of the moderator is to reduce the speed of neutrons in nuclear fission reactions. This is in comparison to 0.19 jobs in coal, 0.05 jobs in gas-fired plants, and 0.05 in wind power. D. Decrease the number of electrons In a gas cooled rector(GCR).....is used as moderator and coolant respectively. Although moderators are necessary in most nuclear reactors this does not mean to say that all reactors require moderators. Everyday Science Mcqs Everyday Science Mcqs. The fast neutrons are absorbed or slowed by the nuclei of a graphite moderator, which allows just enough slow neutrons to continue the fission chain reaction at a constant rate. Slow down the speed of the neutrons C. Increase the number of elections D. Decrease the number of electrons E. None of these. Reduce temperature. Typically-used moderator materials include heavy water, light water, and graphite. As it happens, fuel atoms (like uranium) are more likely to absorb a neutron whizzing by if it’s going slow (see Figure 1). A. A moderator is one of the important components of nuclear power plant helping to maintain neutron population in the thermal energy range. 11. The depletion of the non-renewable energy resources forces the scientist of the world to find a new source of energy which can fulfill the requirement of the electricity demand of the world. IF YOU THINK THAT ABOVE POSTED MCQ IS WRONG. It is here that the concept of a moderator comes in the picture. At 1:50 p.m. on December 20, 1951, the world’s first breeder reactor harvested power. Mcq Added by: Farjan Ahmed Soomro. Your email address will not be published. The most common nuclear power plant design uses a Pressurized Water Reactor (PWR). In nuclear reactor: Coolants and moderators A variety of substances, including light water, heavy water, air, carbon dioxide, helium, liquid sodium, liquid sodium-potassium alloy, and hydrocarbons (oils), have been used as coolants. The moderators vary in terms of their moderating abilities, as well as in their costs. Good moderators are free of neutron-absorbing impurities such as boron. Copyright © 2020 Bright Hub PM. Heavy water is still a common moderator in nuclear reactors, most notably in the CANDU reactors and in other pressurized heavy water reactors. (adsbygoogle = window.adsbygoogle || []).push({}); PakMcqs.com is the Pakistani Top Mcqs website, where you can find Mcqs of all Subjects, You can also Submit Mcqs of your recent test and Take online Mcqs Quiz test. B. Submitted by: Farjan Ahmed Soomro. The mechanism of speed control works in such a way that fast moving neutrons strike the nuclei of moderator material which is not efficient at absorbing them but simply slows them down with repeated collisions thus bringing them into the thermal zone. Author has 940 answers and 397.1K answer views In most cases this is true for slow (“thermal”) neutron nuclear reactors where water is used as a coolant. Now these fast neutrons have to be slowed down and brought to lower energy levels if they have to cause successful fission in turn. The problem lies in the fact that whenever a thermal neutron causes fission it also leads to the release of fast neutrons. HVAC: Heating, Ventilation & Air-Conditioning, This post is part of the series: Components of Nuclear Power Plants, Components of Nuclear Power Plant – Reactor Vessel, Components of Nuclear Power Plant – Shielding, Components of Nuclear Power Plant – Control Rods, Components of Nuclear Power Plant – Coolant, Components of Nuclear Power Plant – Reflector, Components of Nuclear Power Plant – Moderator, Components of Nuclear Power Plant – Fuel, Commercial Energy Usage: Learn about Emission Levels of Commercial Buildings, Time to Upgrade Your HVAC? View Answer. Mcq Added by: admin. Control rods can then be inserted into the reactor core to reduce the reaction rate or withdrawn to increase it. Your email address will not be published. In a nuclear power plant, this fission process is controlled in a reactor to generate heat. Radiation is used and produced in nuclear reactors, which controls fission reactions to produce energy and new substances from the fission products. Dense water C. Fresh water D. Heavy water. The moderator helps slow down the neutrons produced by fission to sustain the chain reaction. Heavy water and CO 2. Inside the reactor vessel, the fuel rods are immersed in water which acts as both a coolant and moderator. Radiation is also used … There are also other categories of neutrons based on their energy levels such as slow neutrons, cold neutrons, ultra cold neutrons and so forth. In a nuclear reactor, a moderator is mixed with the uranium fuel to slow down the fast neutrons to the speed of thermal neutrons, which enables fission to occur in a controlled nuclear chain reaction. Enriching uranium made building reactors easier, but required large facilities like those at Oak Ri… The elastic collisions occurring between the fast neutrons and the moderator slow down the neutrons without … A. Ans: d. 8. 3. Solution(By Examveda Team) Neutron moderator. They create 0.5 jobs for every megawatt hour of electricity produced. 24 views. There are several different types of moderating materials, and each have places where they are used more effectively. The boron concentration of the reactor coolant can be changed by the operators by adding boric acid or by diluting with water to manipulate reactor power. If the rate of energy generation is slow, there will be very little electricity generated. There is a certain threshold below which the neutron will not be absorbed by the target nucleus, but that does not mean that above that threshold any neutron can cause fission. The energy released from continuous fission of the atoms of the fuel is harnessed as heat in either a gas or water, and is used to produce steam. Here's What You Need to Know, 4 Most Common HVAC Issues & How to Fix Them, Commercial Applications & Electrical Projects, Fluid Mechanics & How it Relates to Mechanical Engineering, Hobbyist & DIY Electronic Devices & Circuits, Naval Architecture & Ship Design for Marine Engineers, Normal or Light Water is used in majority of the reactors simply because of its cheap and abundant availability. At that time, most graphites were deposited onto boron electrodes, and t… Water is used as both neutron moderator and reactor coolant. A moderator is used in nuclear reactor in order to ? A nuclear power plant is a thermal power station in which the heat source is a nuclear reactor.As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a generator that produces electricity.As of 2018, the International Atomic Energy Agency reported there were 450 nuclear power reactors in operation in 30 countries. Nuclear power plant generates electrical energy using heat energy and Uranium-235 is used as a fuel, to produce that heat. Chain reaction in a nuclear reactor at a critical stateSlow neutrons strike nuclei of uranium-235, causing the nuclei to fission, or split, and release fast neutrons. So, many reactor designs use moderators to make a chain reaction easier to attain. The relative properties of these materials are compared below. The most commonly used moderator in nuclear plants is (a) heavy water (b) concrete and bricks It is located in the reactor core. Yes. The history of heavy water reactors highlights the immense industrial mobilization required by nuclear programs during World War II. The moderator is a component that is part of nuclear reactors. More broadly, a well-functioning domestic civil nuclear “ecosystem” is intertwined with our space and military nuclear capabilities, such as the reactors that power our aircraft carriers and submarines. 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