| Popis: |
The report describes the initial creepdown tests of Zircaloy fuel cladding in which the surface displacements of the specimens have been measured as a function of time. Such measurements were made with a high accuracy, high precision eddy-current device capable of operation at elevated temperatures and pressures. Tests were conducted at 371/sup 0/C (700/sup 0/F) and external pressures of 14.5 to 17.2 MPa (2100 to 2500 psig) on specimens of reactor grade Zircaloy-4 fuel cladding in the unirradiated, stress relieved condition. Data are reported in several forms--as individual radial displacements of the cladding surface with time; as average diameter and ovality changes with time; in sequential photographs of analogue models; and with a preliminary discussion of mathematically modeled surfaces. It is concluded that the creepdown phenomenon, although complicated to test and describe, may not be as difficult to understand as previously thought. Further testing will refine present knowledge of cladding behavior relative to strain behavior under creep conditions. |
