Physics NUCLEAR FUSION AND FISSION

Please Wait... While Loading Full Video

NUCLEAR FUSION AND FISSION

Nuclear Fission

The breaking of a heavy nucleus into two or more fragments of comparable mass. with the release of tremendous energy is called as nuclear fission.

The most typical fission reaction occurs when slow moving neutrons strike `text( )_92U^(235)`. The following nuclear reaction takes place.

`text( )_92U^(235) + text( )_0n^1` `->` `text( )_56Ba^(141) + text( )_36Kr^(92) + 3text( )_0n^1 + 200 MeV`

If more than one of the neutrons produced in the above fission reaction are capable of inducing a fission reaction (provided `U^(235)` is available), then the number of fission taking place at successive stages goes increasing at a very brisk rate and this generates a series of fission. This is known as chain reaction. The chain reaction takes place only if the size of the fissionable material (`U^(235)`) is greater than a certain size called the critical size.

If the number of fission in a given interval of time goes on increasing continuously, then a condition of explosion is created. ln such cases, the chain reaction is known as uncontrolled chain reaction. This forms the basis of atomic bomb. In a chain reaction, the fast moving neutrons are absorbed by certain substances known as moderators (like heavy water), then the number of fissions can be controlled and the chain reaction is such cases is known as controlled chain reaction. This forms the basis of a nuclear reactor.

The breaking of a heavy nucleus into two or more fragments of comparable mass. with the release of tremendous energy is called as nuclear fission.

The most typical fission reaction occurs when slow moving neutrons strike `text( )_92U^(235)`. The following nuclear reaction takes place.

`text( )_92U^(235) + text( )_0n^1` `->` `text( )_56Ba^(141) + text( )_36Kr^(92) + 3text( )_0n^1 + 200 MeV`

If more than one of the neutrons produced in the above fission reaction are capable of inducing a fission reaction (provided `U^(235)` is available), then the number of fission taking place at successive stages goes increasing at a very brisk rate and this generates a series of fission. This is known as chain reaction. The chain reaction takes place only if the size of the fissionable material (`U^(235)`) is greater than a certain size called the critical size.

If the number of fission in a given interval of time goes on increasing continuously, then a condition of explosion is created. ln such cases, the chain reaction is known as uncontrolled chain reaction. This forms the basis of atomic bomb. In a chain reaction, the fast moving neutrons are absorbed by certain substances known as moderators (like heavy water), then the number of fissions can be controlled and the chain reaction is such cases is known as controlled chain reaction. This forms the basis of a nuclear reactor.

Nuclear Fusion

The process in which two or more light nuclei are combined into a single nucleus with the release of tremendous amount of energy is called as nuclear fusion. Like a fission reaction, the sum of masses before the fusion (i.e. of bigger nucleus) and this difference appears as the fusion energy. The most typical fusion reaction is the fusion of two deuterium nuclei into helium.

`text( )_1H^2 + text( )_1H^2 -> text( )_2He^4 + 21.6 MeV`

For the fusion reaction to occur, the light nuclei are brought closer to each other (with a distance of `10^(-14) m`). This is possible only at very high temperature to counter the repulsive force between nuclei. Due to this reason, the fusion reaction is very difficult to perform. The inner core of sun is at very high temperature, and is suitable for fusion. Ln fact the source of sun's and other star's energy is the nuclear fusion reaction.

The process in which two or more light nuclei are combined into a single nucleus with the release of tremendous amount of energy is called as nuclear fusion. Like a fission reaction, the sum of masses before the fusion (i.e. of bigger nucleus) and this difference appears as the fusion energy. The most typical fusion reaction is the fusion of two deuterium nuclei into helium.

`text( )_1H^2 + text( )_1H^2 -> text( )_2He^4 + 21.6 MeV`

For the fusion reaction to occur, the light nuclei are brought closer to each other (with a distance of `10^(-14) m`). This is possible only at very high temperature to counter the repulsive force between nuclei. Due to this reason, the fusion reaction is very difficult to perform. The inner core of sun is at very high temperature, and is suitable for fusion. Ln fact the source of sun's and other star's energy is the nuclear fusion reaction.

SiteLock