A study on the radiation damage and recovery of neutron irradiated vessel steel using magnetic Barkhausen noise

Abstract

In nuclear power plants, neutron embrittlement of pressure vessel steels has been one of the main concerns. The use of micromagnetic Barkhausen emissions is a promising method to monitor the variations in microstructural and subsurface stress states due to their influence on these emissions. Measurements of these emissions can reveal neutron irradiationdegradation in nuclear power plant components. Samples which were irradiated at differentneutron fluences and annealed at different temperatures were obtained from three reactor surveillance programs. The results of different neutron fluences and annealing procedures showed noticeable fractional changes in the magnetic Barkhausen effect signal parameter, ΔMBE/MBE, and in the mechanical properties of these specimens. For example, increased intensity of neutron fluence decreased the ΔMBE/MBE as well as impact energy and upper-shelf energy, but increased Rockwell hardness and yield strength. Typical changes in this parameter were in the range from −20% to −45% for fluences of up to 25×10 18 n cm −2. A study on the radiation damage and recovery of neutron irradiated vessel steel using magnetic Barkhausen noise In nuclear power plants, neutron embrittlement of pressure vessel steels has been one of the main concerns. The use of micromagnetic Barkhausen emissions is a promising method to monitor the variations in microstructural and subsurface stress states due to their influence on these emissions. Measurements of these emissions can reveal neutron irradiation degradation in nuclear power plant components. Samples which were irradiated at different neutron fluences and annealed at different temperatures were obtained from three reactor surveillance programs. The results of different neutron fluences and annealing procedures showed noticeable fractional changes in the magnetic Barkhausen effect signal parameter, AMBE/MBE, and in the mechanical properties of these specimens. For example, increased intensity of neutron fluence decreased the AMBE/MBE as well as impact energy and upper-shelf energy, but increased Rockwell hardness and yield strength. npical changes in this parameter were in the range from-20% to-45% for fluences of up to 25 X lOI n cmm2.

Materials Degradation and Detection (MD2): Deep Dive Final Report

“…While it has been frequently shown that mechanical changes in steels, such as those resulting from neutron irradiation, have effects on the major loops of magnetization (e.g., Park et al 2004a;Park et al 1997a)), Barkhausen noise (e.g., (Chang et al 2002;Altpeter et al 2001;Park et al 1999d;Park et al 1999b;Sipahi et al 1994)), impedance spectroscopy (Park et al 2004b;Park et al 2004a), and ferromagnetic resonance (Park et al 2004b;Park et al 2003), only one group has looked at the effects of mechanical changes and precipitation on minor hysteresis loops where the magnetic history is not merely between positive and negative saturations Kobayashi et al 2009Kobayashi et al , 2008Takahashi et al 2005). First order reversal curves (FORCs) are similar to minor loops but consist of only part of the loop.…”

“…Others realized that micromagnetics could be used for NDE of both nuclear pressure vessel steels (Hsu and Chang 1996;Blaszkiewicz 1996;Ara et al 1996;Dobmann 1994;Kee-Ok et al 1999;Park et al 1999a;Park et al 1999c;Sukegawa et al 2000;Park et al 2000;Kikuchi et al 2006;Park et al 1999d;Park et al 1999b) and power plant steels (Ginsztler et al 1994). Consequently, these steels were soon being routinely investigated using these methods and correlations were developed for hardening and aging.…”

“…Regardless of the alloy, magnetic Barkhausen noise is almost always decreased with irradiation (Sipahi et al 1994;Park et al 1997b) due to domain wall pinning, and typically coercivity and permeability are increased, though not always (Park et al 1997a;Park et al 1999b). Irradiation processes that produce point defects and small defect clusters can be effectively probed as a function of dose for small doses using these methods and linear responses are found initially.…”

Magnetic Hysteresis and Barkausen Noise in Plastically Deformed Steel Sheets

“…Detection and analysis of the BN have long since been employed for nondestructive sensing of many structural phenomena and physical effects in steels, including austenitic steels, exploiting the dependence of the significant parameters of the noise on specific macroscopic parameters of the material [10][11][12][13][14][15][16][17]. Actually, BN measurements do not provide absolute quantities and one generally looks at the variation of the BN properties with respect to a reference state.…”

Preliminary Phase Field Computational Model Development

“…The goal is to use Barkhausen noise emission as the NDE method. It has been shown many times that mechanical changes in steels, such as those resulting from neutron irradiation, have effects on Barkhausen noise (e.g., Sipahi et al 1994;Park et al 1999a;Park et al 1999b;Altpeter et al 2001;Chang et al 2002) and the major loops of magnetization (e.g., Park et al 1997;Park et al 2003;Park et al 2004). Therefore major hysteresis loops, such as those obtained with a vibrating sample magnetometer (VSM) where magnetization is saturated at positive and negative field values, should be obtained on laboratory specimens.…”