Table 11. Thermal Neutron Constants (cross sections and average total neutron yield) for fissile actinides for neutrons with energy 0.0253 eV. 
The 0.4 % unrecognized systematic uncertainty is included in the uncertainties of the total neutron yields (nu-bar).  

                      U-233        U-235        Pu-239      Pu-241

Fission CS, barn     533.0+-2.2   587.3+-1.4   752.4+-2.2  1023.6+-10.8

Capture CS, barn     44.9+-0.9    99.5+-1.3    269.8+-2.5  362.3+-6.1

Scattering CS, barn  12.2+-0.7    14.09+-0.22  7.8+-1.0    11.9+-2.6

Nu-bar, Total average
neutron yield 
per 1 fission        2.487+-0.011 2.425+-0.011 2.878+-0.013 2.940+-0.013

Total average neutron yield per 1 fission in Cf-252(sf) 3.764+-0.016