| Popis: |
Thimble tubes in a nuclear power plant are used to insert detectors to measure the distribution of neutron fluence rate of the nuclear reactor core. It is important to inspect the thimble tubes’ damage timely to avoid accidents and economic losses. However, as the diameter of the tube is only 5mm, it is challenging to develop such a small array probe that suits thimble tubes. This paper presents a new probe with array tunnel magnetoresistance (TMR) sensors and elliptical excitation coil for thimble tube inspection. The probe consists of 8 TMR sensors, which are wire bonded on an elliptical circuit board together with a bare die operational amplifier chip. A magnetic field image is generated by the probe in a scan, which is sensitive to both circumferential and axial defects due to the elliptical excitation. A prototype probe has been developed and tested. |
