Question

Consider the following statements: 

In a nuclear reactor, self-sustained chain reaction is possible, because: 

1. more neutrons are released in each of the fission reactions. 

2. the neutrons immediately take part in the fission process. 

3. the fast neutrons are slowed down by graphite. 

4. every neutron released in the fission reaction initiates further fission. 

Which of these statements are correct? 

(a) 1, 2 and 3 (b) 1 and 3 (c) 2 and 4 (d) 2, 3 and 4

Answer 1

(a) A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. The most common use of nuclear reactors is for the generation of electrical power and for the power in some ships. In every fission reaction in which uranium nuclei splits up to give smaller nuclei three more neutrons are produced which further results into splitting of heavy uranium nuclei and more number of neutrons will be produced. Thus, statement, 1 and 2 are correct. In nuclear reactor all the neutrons produced can not take part in fission reaction, else reaction can turn out extremely violent. Thus, graphite rods are used as a control rods to slow down the speed of fast moving neutrons. Thus, statement 3 is also correct.