Detection of neutron irradiaton induced degradation of reactor steel by magnetic method

G Vértesy,A Gasparics,F Gillemot,I Szenthe,I Uytdenhouwen,R Chaouadi

doi:10.1088/1757-899x/903/1/012011

Abstract

A novel nondestructive method, based on step by step measurement of minor magnetic hysteresis loops was used to determine the neutron irradiation induced degradation of nuclear reactor pressure vessel steel material. This method is called Magnetic Adaptive Testing (MAT), and two types of reactor steel material were investigated: base material type 22NiMoCr37 and weld material type 18MND5. Charpy geometry samples were irradiated by neutrons at the BR2 in SCK•CEN. The neutron irradiation generated structural changes in the material. As a result of our measurement, it was shown that this degradation could be detected by MAT measurements. Charpy impact tests were also done on the investigated samples and the results of these measurement were compared with the nondestructively determined magnetic quantities. It was shown that a closely linear correlation existed between the ductile-to-brittle transition temperature (DBTT) and MAT parameters.

Highlights

Pressurized water reactors are applied in majority the nuclear power plants
Magnetic Adaptive Testing (MAT) measurements were performed on two series of the above described reactor steel samples before and after neutron irradiation
Optimal means that these descriptor has the largest sensitivity with respect to the independent parameter, which characterizes the material degradation, and at the same time they are reliable and well reproducible The exact description on how these optimal descriptors are determined is given in Ref. [13]

Summary

Introduction

Pressurized water reactors are applied in majority the nuclear power plants. The reactor pressure vessel (RPV) is the most important part from point of view of safety. A novel nondestructive method, based on step by step measurement of minor magnetic hysteresis loops was used to determine the neutron irradiation induced degradation of nuclear reactor pressure vessel steel material. Charpy impact tests were done on the investigated samples and the results of these measurement were compared with the nondestructively determined magnetic quantities.

Results

Conclusion