Source Enhancement Measurement to Determine vσ_ƒ of Uranium-238 for Californium-252 Spontaneous Fission Neutrons

The increase in intensity of a ²⁵²Cf neutron source surrounded by uranium depleted in the ²³⁵U isotope has been measured, and the results of this experiment were used to determine of²³⁸U for ²⁵²Cf spontaneous-fission neutrons. The measurement was performed in the TRIGA Mark III reactor, using the multiplication property of a subcritical TRIGA core. A Monte Carlo calculation was performed, which employed ENDF/B-III data, to provide analytical results for comparison with the measurements. The source enhancement obtained using a depleted uranium cylinder surrounding the ²⁵²Cf source was measured to be (7.35 ± 0.20)% compared with a calculated value of (7.11 ± 0.15)%. The calculated results, using ENDF/B-III data, agree with the measurement within the uncertainty of the evaluated values of v and σ_ƒ.