RD-0410 (РД-0410, GRAU index: 11B91) was a Soviet nuclear thermal rocket engine developed by the Chemical Automatics Design Bureau[1] in Voronezh from 1965 through the 1980s using liquid hydrogen propellant.
[2] The engine was ground-tested at the Semipalatinsk Test Site,[3] and its use was incorporated in the Kurchatov Mars 1994 crewed mission proposal.
The design of the reactor core included thermal insulation between uranium carbide/tungsten carbide fuel and the zirconium hydride moderator.
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.
[4] The hydrogen boost turbopump was designed by KBKhA in Voronezh.