In service evaluation of the core vessel welds of the experimental reactor EWA

The circumferential welds of the core vessel had been tested radiographically, before the reactor start-up. After twelve years work, the evaluation of the welds state, without the disassemble and removal of the core vessel, has been performed. The tests have been carried out by ultrasonic method, which permitted to do the work remotely under the layer of reactor water. Because it has been difficult to compare and evaluate the results of the tests using different methods, comparative tests on a sample core vessel have been performed. The report presents the procedure of testing, the special equipment for remote work and an attempt of the results interpretation. (author)