Application of acoustic emission techniques to thermal ratcheting tests of LMFBR primary coolant piping

For the practical application of acoustic emission (AE) to the structural integrity monitor for the primary coolant piping of the liquid-metal fast breeder reactor, it is necessary to investigate AE characteristics of the piping components under complicated loading of mechanical and thermal stress in the presence of the background flow noise. This paper presents the cooperative work by the Power Reactor and Nuclear Fuel Development Corporation (PNC) and Central Research Institute of Electric Power Industry (CRIEPI) on the AE application to thermal ratcheting tests of 304 stainless-steel pipes in the liquid-Sodium Loop. The main objectives of this work are as follows: - (1) Signal acquisition under the liquid-sodium flow condition similar to the practical plant. (2) AE characteristics during the thermal ratcheting test. (3) Changes of AE characteristics due to various types of piping failure. Three test have been performed under different test conditions, and demonstrated the effectiveness of the AE technique as a monitoring tool. Future works to be done have been pointed out as follows. (1) Clarification of physical meanings of AE characteristics acquired. (2) Investigation of the quantitative correlation between some AE parameters and the degrees of structural failure. (author)