Overview of coupled plasma-neutronics integrated modelling for D-T, D, and He plasmas in JET and ITER

Accurate measurements and computational predictions of fusion power are essential for developing and sustaining burning plasma conditions in magnetically confined devices. This contribution is an overview of a decade's worth of work on developing integrated modelling workflows for coupled plasma-neutronics simulations, enhancing the fidelity of fusion yield measurements and extrapolations for future fusion reactors, such as ITER, DEMO, and SPARC. The international collaborative effort utilizes state-of-the-art plasma transport (TRANSP, JINTRAC), orbit tracking (NUBEAM, LOCUST GPU), kinematics (DRESS), and neutronics codes (MCNP) to produce first-of-a-kind high-fidelity neutron and gamma source models. These are based on interpretive and predictive plasma simulations, with bespoke neutron sources computed and validated for individual plasma discharges. The source models are used in support of in-situ P_fus calibration procedures, synthetic diagnostics codes, neutron and photon transport shielding and radiation safety studies, and surrogate models for fusion performance estimates. We detail the application and validation of coupled plasma-neutronics workflows on JET D plasmas with MeV-range fast ions driving large neutron spectrum anisotropies, recent JET D-T plasmas that produced record fusion yields, JET He plasmas with neutron emission dominanted by fusion between energetic protons and metallic beryllium impurities, and ITER's baseline 15 MA/5.3 T D-T scenario based on core-SOL-divertor coupled JINTRAC simulations demonstrating Qfus ≈ 10.