Abstract:
The grid-to-rod fretting wear methodology is developed based on Archard wear equation to calculate the cladding wear depth of CNPP fuel rod during its residence time within the reactor core. This methodology is coupled with FRV, FRPV, FRCB and ANSYS computer codes to determine the input parameters such as residual spacer grid spring force, effective sliding distance, cladding creep down, RMS displacement at dimple location, and initial hold-down force of the spacer grid spring etc. of wear equation. After determining all these parameters, the wear depth of CNPP fuel rod due to FIV (considering the effects of thermal expansion, cladding creep and irradiation induced spring relaxation) is calculated to be about 9.5 μm which is less than the design criterion (i.e., 10 % of the Zircaloy-4 cladding tube wall thickness, 70 μm at the end of life). In case of CNPP, for an initial spring force of 14.5 N the slippage of fuel rod occurs when the spacer grid spring relaxation caused by irradiation reaches to 76%.Based on these results, it is expected that the fretting wear depth of CNPP fuel rod will remain within the acceptable limits during its entire lifetime.
Page(s):
34-45
DOI:
DOI not available
Published:
Journal: Technical Journal, Volume: 17, Issue: 1, Year: 2012