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Encyclopedia > Control rod

A control rod is a rod made of a chemical element capable of absorbing many neutrons without decaying themselves. They are used in nuclear reactors to control the rate of decay of uranium and plutonium. A chemical element, often called simply element, is a chemical substance that cannot be divided or changed into other chemical substances by any ordinary chemical technique. ... Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 940 MeV/c² (1. ... Core of a nuclear reactor A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate (as opposed to a nuclear explosion, where the chain reaction occurs in a split second). ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Atomic mass 238. ... General Name, Symbol, Number plutonium, Pu, 94 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery white Atomic mass (244) g/mol Electron configuration [Rn] 5f6 7s2 Electrons per shell 2, 8, 18, 32, 24, 8, 2 Physical properties Phase solid Density (near r. ...


A control rod is removed from or inserted into the central core of a nuclear reactor in order to control the neutron flux - increase or decrease the number of neutrons which will split further uranium atoms. This in turn affects the temperature of the reactor, the amount of steam generated, and hence the electricity produced. A Nuclear reactor core is that portion of a nuclear reactor containing the fuel components where the nuclear reactions take place. ... Core of a nuclear reactor A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate (as opposed to a nuclear explosion, where the chain reaction occurs in a split second). ... neutron flux n : the rate of flow of neutrons; the number of neutrons passing through a unit area in unit time via dictionary. ... Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Atomic mass 238. ... In physical chemistry and in engineering, steam refers to vaporized water. ... Electricity is a property of matter that results from the presence of electric charge. ...


Control rods stand vertically within holes through the pile, and are lifted partially out to allow a chain reaction to occur. The number of control rods lifted and the distance by which they are lifted can be varied to control the rate of the reaction. Albert Einsteins letter to President Roosevelt in 1939 about his concern, about (Nuclear chain reactions) Click for closeup of letter A nuclear chain reaction occurs when on average more than one nuclear reaction is caused by another nuclear reaction, thus leading to an exponential increase in the number of...


In most reactor designs, as a safety measure, control rods are attached to the lifting machinery by electromagnets, rather than direct mechanical linkage. This means that automatically in the event of power failure, or if manually invoked due to failure of the lifting machinery, the control rods will fall, under gravity, fully into the pile to stop the reaction. Quickly shutting down a reactor in this way is called scramming the reactor. An electromagnet is a type of magnet in which the magnetic field is produced by a flow of electric current. ... A SCRAM is an emergency shutdown of a nuclear reactor - though the term has been extended to cover shutdowns of other complex operations, such as server farms and even large model railroads (see Tech Model Railroad Club). ...


Originally the control rods hung above the reactor, suspended by a rope. In an emergency a person assigned to the job would take a fire axe and cut the rope, allowing the rods in fall into the reactor and stop the fission. At some point the title of the person assigned this duty was given as SCRAM, or Safety Control Rod Ax Man. This term continues in use today as the phrase "scram" to describe a shutting down of a reactor by dropping the control rods. For other uses, see Axe (disambiguation). ... An induced nuclear fission event. ... A SCRAM is an emergency shutdown of a nuclear reactor - though the term has been extended to cover shutdowns of other complex operations, such as server farms and even large model railroads (see Tech Model Railroad Club). ...


Mismanagement or failure of control rods was a cause or an aggravating factor of many nuclear accidents, including the SL-1 explosion. Pathways from airborne radioactive contamination to man This is a list of notable accidents involving nuclear material. ... The SL-1, the Stationary Low-Power Reactor Number One, was a U.S. experimental military nuclear power reactor. ...


Control rods are commonly composed of silver, indium and cadmium. Other elements that can be used include boron, carbon, cobalt, hafnium, gadolinium and europium. General Name, Symbol, Number silver, Ag, 47 Chemical series transition metals Group, Period, Block 11, 5, d Appearance lustrous white metal Atomic mass 107. ... General Name, Symbol, Number indium, In, 49 Chemical series poor metals Group, Period, Block 13, 5, p Appearance silvery lustrous gray Atomic mass 114. ... General Name, Symbol, Number cadmium, Cd, 48 Chemical series transition metals Group, Period, Block 12, 5, d Appearance silvery gray metallic Atomic mass 112. ... General Name, Symbol, Number boron, B, 5 Chemical series metalloids Group, Period, Block 13, 2, p Appearance black/brown Atomic mass 10. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... General Name, Symbol, Number cobalt, Co, 27 Chemical series transition metals Group, Period, Block 9, 4, d Appearance metallic with gray tinge Atomic mass 58. ... General Name, Symbol, Number hafnium, Hf, 72 Chemical series transition metals Group, Period, Block 4, 6, d Appearance gray steel Atomic mass 178. ... General Name, Symbol, Number gadolinium, Gd, 64 Chemical series lanthanides Group, Period, Block ?, 6, f Appearance silvery white Atomic mass 157. ... General Name, Symbol, Number europium, Eu, 63 Chemical series lanthanides Group, Period, Block ?, 6, f Appearance silvery white Atomic mass 151. ...


 
 

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