A Hybrid Transport Point-Kinetic method for simulating source transients in subcritical systems

► The paper presents a novel kinetic approximation, tailored to model source-driven transients. ► HTPK is a hybrid technique between rigorous Boltzmann equation and approximate PK. ► HTPK describes the first few neutron generations by means of collisionless transport theory. ► Higher order generations are collectively accounted for with a lumped parameter model. ► HTPK remarkably increases the PK accuracy with a limited additional computational cost.