MEASURING METHOD OF SOUNDNESS OF ZIRCONIUM ALLOY IN NUCLEAR REACTOR

PURPOSE:To measure aging soundness nondestructively and easily, by measuring the thicknesses of the oxide layers produced on the surface of zirconium alloys nondestructively and determining the min. thicknesses of the alloy bases from the max. thicknesses thereof. CONSTITUTION:Test pieces of zirconium alloys having the same material quality as the quality of the zirconium alloys in a nuclear reactor to be measured are placed under accelerated oxidation test conditions, and are removed at every specified time, then the max. thicknesses of the oxide layers produced on the respective surfaces as well as the min. thicknesses of the matrices are measured. The relations between the max. thicknesses of the oxide layers and the min. thicknesses of the matrices of the test pieces are determined by a method of least squares in accordance with the measured values. The max. thickness of the oxide layers in the channel box of the actual reactor is measured by an eddy current method, and the value is substituted in the relations, by which the min. thickness of the matrices is determined. The value is compared with the limit value of the thicknesses of the matrices, whereby soundness is decided.