4 Effective Delayed Neutron Fraction
117
As shown in Tables 4.16, 4.17, 4.18 and 4.19, numerical results (eigenvalue calculations) by MCNP6.1 with JENDL-4.0 demonstrated good agreement with the experimental data of reactivity in the critical cores. JENDL-4.0 was taken as a reference
library by comparing it with ENDF/B-VII.1.
4.4.2.2 Experimental Analyses of β eff /
Kinetics parameters β eff , and Rossi-α, and k eff values were obtained by the MCNP
eigenvalue calculations and compared with those of JENDL-4.0 and ENDF/B-VII.1,
for critical and near-critical states, as shown in Tables 4.20, 4.21, and 4.22. For the
two critical cores shown in Figs. A4.1 and A4.4, JENDL-4.0 demonstrated a small
difference between the super-critical (Table 4.20) and the critical (Table 4.21) states,
Table 4.20 Comparison between kinetic parameters by MCNP6.1 with JENDL-4.0 and ENDF/BVII.1 (# of HEU plates: 3016 in Fig. A4.1) (Ref. [23])
Parameter
JENDL-4.0
ENDF/B-VII.1
Super-critical core (clean core)
β eff [pcm]
813 ± 10
801 ± 10
[μs]
31.67 ± 0.07
31.26 ± 0.07
Rossi-α [s −1 ] 256.89 ± 3.11 256.18 ± 3.11
Critical core (partial insertion of C3 rod) β eff [pcm]
818 ± 10
800 ± 10
[μs]
30.91 ± 0.07
30.69 ± 0.07
Rossi-α [s −1 ] 264.55 ± 3.23 260.66 ± 3.17
Table 4.21 Comparison between kinetic parameters by MCNP6.1 with JENDL-4.0 and ENDF/BVII.1 (# of HEU plates: 3008 in Fig. A4.4) (Ref. [23])
Parameter
JENDL-4.0
ENDF/B-VII.1
Super-critical core (clean core)
β eff [pcm]
812 ± 10
802 ± 10
[μs]
31.57 ± 0.07
31.30 ± 0.07
Rossi-α [s −1 ] 257.22 ± 3.11 256.35 ± 3.11
Critical core (partial insertion of C2 rod) β eff [pcm]
821 ± 10
801 ± 10
[μs]
31.33 ± 0.07
30.03 ± 0.07
Rossi-α [s −1 ] 262.22 ± 3.17 258.09 ± 3.15
Table 4.22 Comparison between kinetic parameters by MCNP6.1 with JENDL-4.0 and ENDF/BVII.1 (# of HEU plates: 3000; subcritical core in Figs. A4.3a and A4.6a) (Ref. [23])
Parameter
JENDL-4.0
ENDF/B-VII.1
Subcritical core (clean core)
β eff [pcm]
806 ± 10
796 ± 10
[μs]
31.71 ± 0.07
31.42 ± 0.07
Rossi-α [s −1 ]
254.05 ± 3.07
253.35 ± 3.09
117
As shown in Tables 4.16, 4.17, 4.18 and 4.19, numerical results (eigenvalue calculations) by MCNP6.1 with JENDL-4.0 demonstrated good agreement with the experimental data of reactivity in the critical cores. JENDL-4.0 was taken as a reference
library by comparing it with ENDF/B-VII.1.
4.4.2.2 Experimental Analyses of β eff /
Kinetics parameters β eff , and Rossi-α, and k eff values were obtained by the MCNP
eigenvalue calculations and compared with those of JENDL-4.0 and ENDF/B-VII.1,
for critical and near-critical states, as shown in Tables 4.20, 4.21, and 4.22. For the
two critical cores shown in Figs. A4.1 and A4.4, JENDL-4.0 demonstrated a small
difference between the super-critical (Table 4.20) and the critical (Table 4.21) states,
Table 4.20 Comparison between kinetic parameters by MCNP6.1 with JENDL-4.0 and ENDF/BVII.1 (# of HEU plates: 3016 in Fig. A4.1) (Ref. [23])
Parameter
JENDL-4.0
ENDF/B-VII.1
Super-critical core (clean core)
β eff [pcm]
813 ± 10
801 ± 10
[μs]
31.67 ± 0.07
31.26 ± 0.07
Rossi-α [s −1 ] 256.89 ± 3.11 256.18 ± 3.11
Critical core (partial insertion of C3 rod) β eff [pcm]
818 ± 10
800 ± 10
[μs]
30.91 ± 0.07
30.69 ± 0.07
Rossi-α [s −1 ] 264.55 ± 3.23 260.66 ± 3.17
Table 4.21 Comparison between kinetic parameters by MCNP6.1 with JENDL-4.0 and ENDF/BVII.1 (# of HEU plates: 3008 in Fig. A4.4) (Ref. [23])
Parameter
JENDL-4.0
ENDF/B-VII.1
Super-critical core (clean core)
β eff [pcm]
812 ± 10
802 ± 10
[μs]
31.57 ± 0.07
31.30 ± 0.07
Rossi-α [s −1 ] 257.22 ± 3.11 256.35 ± 3.11
Critical core (partial insertion of C2 rod) β eff [pcm]
821 ± 10
801 ± 10
[μs]
31.33 ± 0.07
30.03 ± 0.07
Rossi-α [s −1 ] 262.22 ± 3.17 258.09 ± 3.15
Table 4.22 Comparison between kinetic parameters by MCNP6.1 with JENDL-4.0 and ENDF/BVII.1 (# of HEU plates: 3000; subcritical core in Figs. A4.3a and A4.6a) (Ref. [23])
Parameter
JENDL-4.0
ENDF/B-VII.1
Subcritical core (clean core)
β eff [pcm]
806 ± 10
796 ± 10
[μs]
31.71 ± 0.07
31.42 ± 0.07
Rossi-α [s −1 ]
254.05 ± 3.07
253.35 ± 3.09