GK
NUCLEAR SCIENCE
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
1100
|
|
|
2200
|
|
|
3300
|
|
|
4400
|
Detailed explanation-1: -Explanation: The velocity of thermal (slow) neutrons triggering nuclear fission reaction (having energy equal to 0.025 eV) is about 2200 m/sec.
Detailed explanation-2: -When a slow neutron is captured by a 23592U nucleus, a fission energy released is 200 MeV. If power of nuclear reactor is 100 W then rate of nuclear fission is: A. 3.6×106s−1.
Detailed explanation-3: -From this, the number of collisions needed to bring a neutron from an initial energy E0 to a given energy E, is given by (1/x)ln(E0 / E). Thus the number of collisions required to slow down a 2 MeV neutron to 0.025 eV is given by ln(2´106/0.025) / x.
Detailed explanation-4: -For uranium-235 (total mean fission energy 202.79 MeV), typically 169 MeV appears as the kinetic energy of the daughter nuclei, which fly apart at about 3% of the speed of light, due to Coulomb repulsion. Also, an average of 2.5 neutrons are emitted, with a mean kinetic energy per neutron of 2 MeV (total of 4.8 MeV).