RD-0410 (РД-0410, GRAU index: 11B91) was a Soviet nuclear thermal rocket engine developed from 1965 through the 1980s using liquid hydrogen propellant. The engine was ground-tested at the Semipalatinsk Test Site, and its use was incorporated in the Kurchatov Mars 1994 crewed mission proposal.
This engine had slightly higher performance (exhaust temperature and specific impulse) over NERVA (the U.S. nuclear thermal rocket engine project). The design of the reactor core included thermal insulation between uranium carbide/tungsten carbide fuel and the zirconium hydride moderator. This solution allowed for a very compact reactor core design. Hydrogen flow cooled the moderator first allowing to keep very low neutron energy and high fission cross-section, then it was heated by the direct contact to the fuel rods. To prevent the chemical reaction between carbide and hydrogen, about 1 percent of heptane was added to the hydrogen after the moderator passage.
TEM, an evolved design, is under development as of 2018[update].