Study of the magnetization work of RPV steel in dependence on neutron irradiation

Abstract

The reactor pressure vessel (RPV) steel exposed to neutron radiation during operation of nuclear power plant has to suffer the neutron irradiation degradation. For monitoring the radiation damage, especially using non-destructive evaluation methods, the magnetization work W of RPV steel subjected to different neutron radiation fluences Φ has been calculated from magnetization curves. It was found out that the W increases exponentially in relation to Φ in dpa, i.e., W = A + K[exp(Φ/Φ0) − 1]. In this equation, the item A denotes the magnetization work of the non-irradiated RPV steel, the parameter Φ0 is the eigenvalue of the neutron radiation fluence, and the parameter K reflects the sensitivity of the magnetization work to the neutron radiation. The magnetization work W, which can be calculated precisely from the magnetization curves without doing the demagnetizing correction, is highly sensitive to the radiation fluence Φ. So that, the neutron radiation fluence Φ in dpa can be quantitatively determined by measuring the magnetization curves of RPV steels.