Currently, the destructive puncture manometry method is used to measure helium pressure inside fuel rods. However, this method is expensive and does not guarantee 100% coverage. Hence the non-destructive testing (NDT) equipment is introduced for non-destructive measurement of helium pressure inside fuel rods.

This study aims to analyze the reliability of NDT testing method for the measurement of helium pressure inside fuel rods.

Three standard rods with helium pressure values of 0.98 MPa, 1.76 MPa, 2.45 MPa, respectively, were selected for experimental test. The experimental fuel rods were first used to obtain the results comparison of heat transfer method and puncture manometry, then the control variates were employed to control the fuel rod temperature, the time interval of a single measurement, and the ambient temperature respectively, so as to determine influencing factors in the NDT method. Finally, reliability analysis of NDT method was performed according to experimental results.

The results of the NDT method are consistent with that of the puncture manometry method at a temperature range of 24~30 oC with less than 0.05 MPa deviation. Minimum repeat measurement time interval for NDT measuring helium pressure of the same standard rod or fuel rod is 2 min.

The NDT method for measuring the helium pressure of fuel rods is reliable, and the measurement results are stable in different environmental conditions.