Optimization of the Neutron Diffraction Stress Measurement Parameters of Beryllium

The parameters of neutron diffraction stress measurement of beryllium on a steady-state reactor have been optimized using a welded beryllium ring. The results show that under the condition of the neutron beam wavelength of 0.1587 nm and neutron flux rate of 2x10(6) n.cm(-2).s(-1), the neutron stress measurement for beryllium can use Be (110) plane, with the diffraction angle 88.2 degrees and the gauge volume 2 mm x2 mm x2 mm. In the first test, the measuring time is 120 s. After 4 runs test at a fixed location, the diffraction curve has an obvious intensity fluctuation and the maximum strain error is about 300 Afterwards, the measuring time extends to 6000 s, revealing the diffraction curve is smooth and has good repeatability. The maximum strain error decreases to less than 50 mu epsilon, and the corresponding stress error for beryllium is 15 MPa. The hoop strain in beryllium ring near the weld line has been measured using the optimized parameters. It indicates the hoop strain trend is basically identical to the literature. This study can establish a basis for the stress measurement of beryllium by neutron diffraction.