Peregrine’s Pulsating Heat Pipe (PHP) technology was applied to an Isothermal Radiator (IRT) design to dramatically improve heat transport for space nuclear power systems and other high-power spacecraft applications. By increasing the effective thermal conductivity of radiator structures to well over 1,000 W/mK, the technology distributes heat more uniformly across the radiating surface, creating a near-isothermal condition that significantly enhances waste heat rejection via radiation. Constructed from high-temperature materials, the passive, autonomous design provides a low-cost, highly reliable, and long-life solution for reactor cooling and spacecraft thermal management without requiring mechanical pumps or external power. Thiseffort focused on optimizing the design to reduce mass while further improving thermal performance, expanding the technology’s potential for next-generation space and satellite thermal control systems.