On the Effective Capture Cross Section of Pu-240 for Reactor Neutrons

Effective reactor capture cross section values for Pu²⁴⁰ were calculated both from experimental plutonium isotopic ratios and from the resonance parameters for the 1 ev resonance. Both methods gave values of about 1200 barns for highly dilute Pu as contrasted to values of about 500 barns which have been reported for reirradiated Pu samples. The 1200 barn figure is consistent with a 2200 meter per second cross section of about 340 barns and a resonance integral of about 8300 barns.