The feasibility of using X-ray diffraction methods to measure residual stresses in uranium and zirconium (Zircaloy-2) was investigated. A precision method was developed for the determination of diffraction peak positions and the precision associated therewith. The statistical tables of Fisher and Yates were used to determine what order polynomial provided the best least squares fit within the known precision of the observed data. It was found that a second-order polynomial provided an adequate regression. With the aid of a desk calculator less than 5 min calculation time is required to determine the peak position to a precision of ±0.01°.

The stress constant for uranium was determined to be 1308 ± 110 psi/0.01° shift in Δ2θ for copper radiation on the (116) planes at 2θ = 158.3°. The stress constant for Zircaloy-2 was determined to be 430 ± 1 psi/0.01° shift in Δ2θ for chromium radiation on the (10,4) planes at 2θ = 156.4°.