Preoperational Tests of the PIRATE Program for Identifying and Assessing the Depth of Defects in Heat Exchangers of Nuclear Power Plants’ Steam Generators

Abstract

The paper presents the results of acceptance and pilot tests developed by the authors of the PIRATE program designed for automatic analysis of eddy current signals during routine monitoring of the metal state of the heat-exchange tubes in steam generators of nuclear power plants with VVER-440 and VVER-1000 reactor plants. As a result of “blind” acceptance tests using certified standard equipment, the detection of realistic defects on specially prepared tube samples with four gradations of the characteristic size (defect depth) and the reliability of the eddy current testing results with a different level of rejection criterion were determined. The obtained values of detectability and depth of defects satisfy the regulatory documents’ requirements. According to the results of acceptance tests, it is possible to use the PIRATE program at nuclear facilities. The purpose of the pilot tests was to compare the results of operational testing obtained during scheduled preventive repairs by regular systems along with the conclusions of experienced expert analysts to the results of the analysis of the same signals by the PIRATE program in automatic mode. Pilot tests were carried out using data from operational monitoring of steam generators for nuclear power plants with both VVER-440 reactors and VVER-1000 reactors. Findings of defects with varying depths also meet the requirements of industry guidance documents. Based on analyzing the criteria for coincidence of the testing data of the heat-exchange tubes generated by the PIRATE program in automatic mode and a regular system, a conclusion was made about the readiness of the program for industrial operation. In addition, it has been shown that the PIRATE program is no less the foreign programs used at domestic nuclear power plants in some functional capabilities.