System and method for in situ testing of the leak-tightness of a tubular

Abstract

System and method for in situ testing of the leak-tightness of a tubular member, which tubular member may be a nuclear steam generator heat transfer tube. The system includes a mandrel insertable into the tube, the mandrel having a pair of spaced-apart expandable bladders surrounding the mandrel. A first channel extends through the mandrel and is in communication with the bladders. A fluid supply circuit is in fluid communication with the first channel for supplying pressurized liquid to the bladders so that the bladders radially expand into sealing engagement with the inner diameter of the tube. As the bladders expand into sealing engagement with the tube, a sealed annular chamber is defined therebetween bounded by the bladders and the inner diameter of the tube. A second channel also extends through the mandrel, the second channel being in fluid communication with the fluid supply circuit at one end thereof and in communication with the chamber at the other and thereof in order to pressurize the chamber with the liquid. A controller is connected to the fluid supply circuit for measuring the flow rate of the liquid flowing through the fluid supply circuit to the chamber. Any crack in the tube wall adjacent the chamber will allow the liquid to escape therefrom at a characteristic flow rate corresponding to the size of the crack. However, the fluid supply circuit maintains the liquid pressure in the chamber so that the pressure and thus the liquid inventory in the chamber remains constant as the liquid leaks through the crack. The controller, which is connected to the flow meter, measures the flow rate and pressure of the liquid flowing through the fluid supply circuit. In view of the fact that the liquid (i.e., water) is incompressible, the flow rate through the crack and the pressure in the chamber are provided by measuring the flow rate and pressure of the liquid flowing through the fluid supply circuit.