Measurements of Delayed Neutron Decay Constants and Fission Yields from ²³⁵U, ²³⁷Np, ²⁴¹Am, and ²⁴³Am

Delayed neutron yields and decay constants for ²³⁵U, ²³⁷Np, ²⁴¹Am, and ²⁴³Am were measured at the Texas A&M University TRIG A reactor using a fast pneumatic transfer system. The detection system consisted of an array of BF₃ proportional counters embedded in a polyethylene cylinder. The measured values of the total delayed neutron yield per 100 fissions from thermal neutron-induced fission of ²³⁵U, ²³⁷Np, ²⁴¹Am, and ²⁴³Am were determined to be 1.59 ± 0.04, 1.29 ± 0.04, 0.49 ± 0.02, and 0.84 ± 0.04, respectively. The newly measured values of delayed neutron group parameters and total yields were compared with other values recommended by Keepin; Waldo, Karam, and Meyer; and Tuttle. Very good agreement was obtained, especially for ²³⁵U.