92-U-231

Reaction 0.0253-eV Maxwellian
Average
g-factor Resonance
Integral
14-MeV Fiss. Spec.
Average
total 282.1 (b) 304.4 (b) 1.079 5.861 (b) 7.718 (b)
elastic 11.73 (b) 13.24 (b) 1.130 2.806 (b) 4.344 (b)
inelastic ( E-thr = 40.17 keV ) 403.3 (mb) 1.073 (b)
(n,2n) ( E-thr = 5.904 MeV ) 175.3 (mb) 2.079 (mb)
(n,3n) ( E-thr = 13.60 MeV ) 282.1 (nb) 85.41 (nb)
fission 250.1 (b) 267.2 (b) 1.068 1.053 (kb) 2.475 (b) 2.194 (b)
(n,fission) 250.1 (b) 267.2 (b) 1.068 1.053 (kb) 1.678 (b) 2.182 (b)
(n,n,fiss) ( E-thr = 2.000 MeV ) 644.9 (mb) 11.81 (mb)
(n,2n,fiss) ( E-thr = 7.500 MeV ) 151.4 (mb) 25.59 (μb)
(n,3nfiss) ( E-thr = 16.00 MeV ) 2.077e-12 (b)
capture 20.01 (b) 22.72 (b) 1.136 160.7 (b) 693.9 (μb) 103.5 (mb)
 
νp 2.442 3.926
νd 3.457e-3 2.397e-3

These cross sections are calculated from JENDL-4.0 at 300K.
The background color of each cell noted a cross section means the order of the cross-section value.
The unit of cross section, (b), means barns, and SI prefixes are used as following.
(kb) → 103(b),   (mb) → 10−3(b),  (μb) → 10−6(b),  (nb) → 10−9(b).

Maxwellian Average :
σmacs(T) =
2
 
 
π
EU
 
EL
σ(E,T) ⋅ E ⋅ exp (
E
  
kBT
) dE
 
EU
 
EL
E ⋅ exp (
E
  
kBT
) dE
,
where T denotes the temperature, and kB the Boltzmann constant. The upper and lower limits of integration, EL and EU are set to 10−5 eV and 10 eV, respectively.
Resonance Integral :
σri(T) =
EU
 
EL
σ(E,T) ⋅
1
 
E
dE ,
with  EL = 0.5 eV  and  EU = 10 MeV.
U-235 Thermal Fission-Neutron Spectrum Average (Fiss. Spec. Average) :
σfacs(T) =
EU
 
EL
σ(E,T) ⋅
 
4
 
πa3b
⋅ exp (
ab E
     
4 a
) ⋅ sinh
 
bE
dE
 
EU
 
EL
 
4
 
πa3b
⋅ exp (
ab E
     
4 a
) ⋅ sinh
 
bE
dE
,
with  EL = 10−5 eV  and  EU = 20 MeV. The parameters a and b are 0.988 MeV and 2.249 MeV−1, respectively.
Westcott g-factor :
g(T) =
σmacs(T)
 
σ(0.0253 eV,T)
 .


νp, νd : numbers of prompt and delayed neutrons per fission.