Page 28 - Dynamics and Control of Nuclear Reactors

3.2 Delayed neutrons 19

Table 3.1 Delayed neutron data for U-235 (thermal fission).
Group Decay constant, λ i (s 21 ) Delayed neutron fraction (β i )
1 0.0126 0.000224
2 0.0337 0.000777
3 0.139 0.000655
4 0.325 0.000723
5 1.13 0.000133
6 3.50 0.000088
Total delayed neutron fraction: 0.0067.

Table 3.2 Delayed neutron data for U-233 (thermal fission).
Group Decay constant, λ i (s 21 ) Delayed neutron fraction (β i )
1 0.0126 0.000224
2 0.0337 0.000777
3 0.139 0.000655
4 0.325 0.000723
5 1.13 0.000133
6 3.50 0.000088
Total delayed neutron fraction: 0.0026.

Table 3.3 Delayed neutron data for Pu-239 (thermal fission).
Group Decay constant, λ i (s 21 ) Delayed neutron fraction (β i )
1 0.0128 0.000077
2 0.0301 0.000656
3 0.124 0.000464
4 0.325 0.000717
5 1.12 0.000189
6 2.69 0.000097
Total delayed neutron fraction: 0.0022.

Table 3.4 Delayed neutron data for U-238 (fast fission).
Group Decay constant, λ i (s 21 ) Delayed neutron fraction (β i )
1 0.0132 0.000213
2 0.0321 0.002247
3 0.139 0.002657
4 0.358 0.006363
5 1.41 0.003690
6 4.02 0.001230
Total delayed neutron fraction: 0.0164.