Studying And Optimization for The Neutron Diffraction Stress Measurement Parameters of Beryllium

Abstract:

The parameters of neutron diffraction stress measurement of beryllium on a steady-state reactor have been studied and optimized using a welded beryllium ring. The results show that under the condition of the neutron beam wavelength of 1.587? and neutron flux rate of 2?106ncm-2s-1, the neutron stress measurement for beryllium can use Be (110) plane, which the diffraction angle is 88.2o. The gauge volume is 2?2?2mm3. In the first test, the measuring time is 120s. After 4 runs test at a fixed location, it is found the diffraction curve has an obvious intensity fluctuation and the maximum strain error is about 300??. Afterwards, the measuring time extends to 6000s, the diffraction curve is smooth and has good repetitive. The maximum starin error decreases less than 50??, which the stress error for beryllium 15 MPa. The hoop strain in beryllium ring near the weld line has been measured using the optimized parameters, which 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.

Key words:Beryllium; neutron diffraction; stress meaurement