Multi-Physics NTR Safety Analyses

Nuclear Thermal Propulsion (NTP) offers high promise to reduce launch mass, decrease mission costs and increase mission effectiveness, particularly for crewed missions to the planets. However, NTP has been plagued with high uncertainties in cost, schedule and safety, particularly launch safety. To reduce programmatic uncertainty, an unambiguous approach to documenting NTP safety prior to, during and after launch needs to be made. Until recently, the multi-physics models and computing power were not available to perform compelling analyses, and testing is prohibitively expensive, and unrevealing in many cases. This proposal directly addresses programmatic uncertainty by providing benchmarked, definitive product capable of documenting the safety of a NTP system during all launch phases. The proposal takes work performed by the SBC under IR&D which has performed detailed hydrocode modeling of a NTP impacting an unyielding surface from heights of 50 and 150 meters. To initiate the effort, it is important to start with simple compaction model, which was accomplished in Phase I with the Taylor impact simulation. Instead of a single neutronics code, LPS demonstrated viability with three codes to better insure reliable results. Phase II will extend this work. It will continue to update the SCCTE-2 NTR design and include any design modifications by NASA contractors. The NTR model will be updated to include important peripherals suchs as turbooo pump assemblies, thrust vector control hardware, plumbing and a propellant tank. These are essential items for a more realistic impact scenario. Further, during Phase I, LPS determined there are a number of materials whose mechanical database is insufficient for unambiguous hydrocode simulations. LPS will deliver a comprhensive test program plan, costs and schedule to resolve these deficiencies. The technical readiness will be improved so End to End Software elements are implemented and interfaced with existing system concepts.