Abstract
<title>Abstract</title> <p>Deep-space missions face a compounded design inefficiency: radiation shielding mass is mandatory yet conventional shields dissipate all absorbed particle energy as heat, returning nothing to a power-constrained system. Here we present RADIANT, a novel six-layer composite addressing both constraints simultaneously, incorporating hydrogen-boron-graphene polyethylene (HBGPE) as the primary radiation stopping and neutron capture layer, cerium-doped scintillation epoxy for radiation-to-photon conversion, and graphene-polycaprolactone for electrical output. Geant4 11.2.2 simulations across 19 beam configurations demonstrated 2.14-fold higher neutron attenuation than equivalent-thickness aluminium (19.90% versus 9.30% at 1 MeV) from a boron-10 component modelled at 95% enrichment (~ 16,700-fold cross-section advantage), with five of 12 configurations achieving complete or near-complete stopping and 7.3-fold attenuation improvement at 60° oblique incidence. Infrared prototype testing demonstrated stable electrical output from 0.69 ± 0.007 (mean ± s.d.) to 131.05 ± 0.47 W·m⁻² under controlled thermal input, while first-principles calculation combining Geant4 energy deposition with established cerium-doped scintillator light yields predicts particle-driven conversion efficiencies of 0.00–1.05%, increasing with oblique incidence angle. The shield maintained output retention above 93.7% to 545°C, withstood 100 N without fracture, and achieved 14.9% lower areal density than equivalent aluminium. These results demonstrate that passive shielding mass can be redesigned to incorporate radiation-to-electrical conversion capability, with the practical magnitude of that contribution under true space radiation requiring direct experimental validation.</p>