| 摘要 |
This paper describes a method for measuring the diametral expansion of the pressure tubes at Gentilly-2 nuclear generating station. The aim is to describe the solution, the calibration tools, and the analytical methods developed for the project. To measure the diametral expansion of the pressure tubes, Hydro-Québec modified the SLARette device and integrated a new module called MED. The measurement syst em is made up of three parts: 1. An inspection head, the MED (Hydro-Québec) module, which has five ultrasonic probes that determine the distance between the inspections head and pressure tube. Measurements are always done under water and they are used to determine t he diameter and thickness of the pressure tubes. 2. A Tomoscan III acquisition system by R/D Tech to scan the five probes and save the data in an A-scan file. 3. An Analytical software: LogaMED (Hydro-Québec). The advanced delivery machine (ADM) equipped with a SLARette device is primarily an axial inspection syste m. The ADM and SLARette device are not capable of performing an axial/rotation al inspection and have no centering system. However, measuring the diametral creep requires spiral scanning and a centered tool. A method that would allow the walls of the tubes to be measured in an uncentered way and to recalculate the diamete rs as if the device were centered has been designed. An automatic analytical software program (LogaMED) was designed to perform the calculation. LogaMED reads A-scan file data and provides the user with information on diameter and thickness. Two methods can be used to determine the diameter. The first consists in moving lengthwise through the tube. Several passes can be done at different angles and the results compiled in LogaMED. The second method is used to measure the diamet er at every angle with an angular displacement (360.degree. rotation). Two of the main problems that had to be resolved were the calibration of the calculation parameters and the determination of measurement uncertainties. We were able to measure the diameters under different conditions such as temperature variations and changes in the aqueous environment (light water and heavy water). In fact, a model was used to develop the calculations for recentering the diameter. Keywords: ultrasonic testing, fuel channel inspection, fuel channel diameter creeping.
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