Abstract
The neutron irradiation embrittlement of four different types of nuclear pressure vessel materials (three base metals and one weld material) were investigated by a magnetic nondestructive testing method, magnetic adaptive testing (MAT). The method is based on the measurement of minor magnetic hysteresis loops on Charpy specimens irradiated by neutrons in the BR2 reactor. Due to the neutron irradiation, the structure of the material was modified. The Charpy impact method is suitable for destructive characterization of material embrittlement. The results of Charpy impact test measurements at SCK CEN Belgian Nuclear Research Centre were compared with the nondestructively measured magnetic parameters. A definite correlation was found between magnetic descriptors and the ductile-to-brittle transition temperature (DBTT), regardless of the type of material or irradiation condition. The results suggest that this “calibration curve“ can be used to estimate the DBTT from non-destructive measurements.
Highlights
Many nuclear power plants having pressurized water vessels operating all over the world were allowed to operate for longer periods than initially foreseen, typically with an additional20 years of operation
The pressure vessels are exposed to harsh operation conditions, which degrade the properties of pressure vessel materials
Discussion materials were measured by the magnetic adaptive testing (MAT) method before and after neutron irradiation
Summary
Many nuclear power plants having pressurized water vessels operating all over the world were allowed to operate for longer periods than initially foreseen, typically with an additional. Metals 2020, 10, 642 specimen with a 10 × 10 mm cross-section, a 45◦ and 2 mm deep V-notch and a length of 55 mm is broken with a swinging hammer and the absorbed energy determined This energy is measured as a function of test temperature, which allows the deriving of the transition curve. One of them is the method based on the Seebeck effect It was found [2,3] that by very precise measurement of the Seebeck coefficient, the non-destructive inspection of the neutron irradiation generated embrittlement of RPV steels was possible. A relatively novel and promising method of non-destructive evaluation, based on magnetic hysteresis measurements, is the so-called magnetic adaptive testing (MAT) [21]. Applicability of MAT is presented in this work for four different RPV steel materials by comparing the destructively measured transition temperature (DBTT) values with the non-destructively determined magnetic descriptors
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