The nondestructive testing of tubes and pipes for nuclear application

Abstract

The directive of the Reactor Safety Commission demands for all materials which are provided for the pressure bearing enclosure of the refrigerant a nondestructive testing with sufficient sensibility. The specification 3201.1 for nuclear application as well as company-internal rules of important manufacturers regulate the requirements derived from the above direction for the NDT of tubes and pipes. For an objective and reproducible testing, equipments with defined characteristics are employed. based on internal specifications, testing equipments are fabricated and then checked with a special computerized test system. Moreover probes are controlled with regard to their acoustic and electric properties. The NDT of heat exchanger tubes and of pipes is given here as an example: Heat exchanger tubes: The tests include the inspection of longitudinal and transverse defects, wall thickness, dimension and tightness. In connection with the NDT, defect catalogues are set up. By this means the chosen test sensitivity is verified, and so the high quality of the tubes is assured. Specially developed eddy-current methods prove that such tested tubes are free of corrosion-causing phases. Pipes: The pipes are tested for longitudinal and transverse defects, for laminations and for wall thickness. To fulfil the demand for an objective and reproducible testing, there was developed and installed an automatic, computer-controlled ultrasonic equipment with 40 probes. Development trends: For the NDT of heat exchanger and boiler tubes an electrodynamic excited ultrasonic test system is evolved which is also able to test curved and installed tubes. The sophisticated testing technology is completed by a qualified education and training of NDT personnel.