Ultra-high-fidelity reactor pressure vessel monitoring using SERF magnetometer arrays

Continuous surveillance of Reactor Pressure Vessels (RPVs) in Pressurized Water Reactors (PWRs) is critical for Long-Term Operation (LTO), yet conventional inspection techniques typically require reactor shutdowns or direct access to high-radiation environments. This study proposes a physics-based Digital Twin framework for remote, non-intrusive monitoring of RPVs using Spin-Exchange Relaxation-Free (SERF) magnetometers. The Digital Twin is formulated as a physics-informed computational surrogate coupling first-principles neutron transport with magnetostatic field modeling and validated constitutive material laws to infer irradiation-induced embrittlement without breaching the pressure boundary. Because full-scale experimentation in operating PWRs is constrained by radiological conditions, the framework is validated using benchmark methodologies employed in safety-critical nuclear analysis, including comparison with International Atomic Energy Agency (IAEA) Coordinated Research Project reference data and reported post-irradiation magnetic measurements. Simulations indicate that an eight-sensor gradiometric SERF array placed on the biological shield wall at approximately 2.5m provides adequate shielding for alkali-vapor cell operation while maintaining sensitivity to permeability perturbations within the RPV wall. The configuration achieves a detection margin of 3.3×10⁸ relative to background magnetic noise, with constitutive validation yielding a Mean Absolute Error of 2.7%.