Inspection of Reactor Steel Degradation by Magnetic Adaptive Testing.

Gábor Vértesy,Inge Uytdenhouwen,Ildikó Szenthe,Antal Gasparics,Ferenc Gillemot

doi:10.3390/ma12060963

Abstract

Degradation of nuclear pressure vessel steel materials, 15Kh2NMFA type and A508 Cl2 type (definition is given in the text) were investigated by a novel magnetic nondestructive testing method, so-called Magnetic Adaptive Testing (MAT), which is based on systematic measurement and evaluation of minor magnetic hysteresis loops. The measured samples were thermally treated by a special step cooling procedure, which generated structural changes in the material. It was found that this type of degradation can be easily followed by magnetic measurements. Charpy impact test were also performed and the results were compared with the magnetic parameters. In case of 15Kh2NMFA steel, a good, reliable and closely linear correlation was found between magnetic descriptors and transition temperature.

Highlights

Pressurized water reactors are typical in most of the currently operating nuclear power plants.The reactor pressure vessel (RPV) is one of the most important safety related part of these plants, and determines the lifetime of them
It was shown that the method of Magnetic Adaptive Testing was found to be a sensitive and reliable way to characterize the structural changes in reactor pressure vessel material
The modification of the transition temperature due to this thermal treatment can be followed by this nondestructive method, and a closely linear correlation was found between Magnetic Adaptive Testing (MAT) descriptors and Charpy 41 Joule transition temperature

Summary

Introduction

The reactor pressure vessel (RPV) is one of the most important safety related part of these plants, and determines the lifetime of them. It is operated at elevated temperature, high pressure, neutron radiation, thermal ageing and low cycle fatigue, which are the main environmental effects that degrade the RPV material properties during service. When a nuclear reactor starts to operate, its pressure vessel steel is still not degraded. The RPV walls are low alloyed ferromagnetic CrNiMo or CrMoV steels. Their critical parts are the forged rings and their welds at the core level

Results

Discussion

Conclusion