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Idaho National Laboratory and the Universities Space Research Association created the Center for Space Nuclear Research (CSNR) in 2005 to foster collaboration with university scientists. CSNR scientists and engineers research and develop advanced space nuclear systems, including power systems, nuclear thermal propulsion, and radioisotopic generators. The CSNR is located at the Center for Advanced Energy Studies (CAES) building in Idaho Falls, Idaho.

  CAES (Center for Advanced Energy Studies)                         INL (Idaho National Laboratory)  

Nuclear Thermal Propulsion

The United States first explored the use of nuclear power in space in the 1950s. Between 1955 and 1972, the U.S. built and tested more than 20 nuclear-propelled rocket engines in the Rover/NERVA program.

Researchers are revisiting the concept, which is viewed as one of the most promising technologies for powering a manned mission to Mars.

CSNR researchers are developing a tungsten-based fuel for use in a nuclear thermal rocket that shares many of the benefits of the graphite fuels developed in the NERVA program -- a lot of energy in a small mass. But unlike graphite fuels, CSNR's tungsten fuel emits a clean, nonradioactive exhaust, a major environmental concern associated with the NERVA project.

The nuclear thermal rocket (NTR) is a "game changing" technology that could be developed, tested, and deployed in the next few decades.

Developing an NTR requires fuel to be fabricated and characterized, a full-scale, surrogate-loaded tungsten fuel element to be demonstrated, and the microstructure and material behavior to be quantified.


Iridium Alloy Modeling

The PuO2 pellets in a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) are contained in an iridium alloy clad to prevent the spread of contamination in the event of a launch or reentry accident.  Thorium is contained in the alloy to prevent grain growth at high temperatures, but thorium can be trapped at the cladding surface as ThO2 if O2 is available.  Oxygen is released or absorbed by changes in the stoichiometry of the plutonia pellets during processing.  This project modeled oxygen release and movement within the MMRTG and explore changes in processing.


Pu-238 Production in ATR

Plutonium-238 production for use in Radioisotope Thermoelectric Generators (RTGs) is becoming increasingly important in the United States but domestic production ceased in late 1980s. Since then, the USA has relied on the stockpiles, some of which were purchased from Russia at the end of the cold war. The plutonium stockpile has steadily decreased due to utilization in RTGs and also due to the decay of Pu-238 with its 88-year halflife. Summer Fellows at CSNR have worked on a series of studies of the feasibility for irradiating Np-237 in the Advanced Test Reactor (ATR) at the INL and the High Flux Isotope Reactor (HFIR) at ORNL.  The studies have evaluated the use of various irradiation positions in the ATR, configurations of target rods, irradiation scenarios and methods for reducing the production of gamma-emitting isotopes, such as Pu-236.