Nuclear Rocket Technologies

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This page is intended to provide technical papers and pictures about nuclear rockets. Solid core Nuclear Rockets (SNCR) such as those developed at Los Alamos during the ROVER/Nerva program (16K) in the 1960s will be depicted. In addition, results from previous and current research on Gas-Core Nuclear Rockets (GCNR) will be shown.


Nuclear rockets utilize fission energy to heat a reactor core to very high temperatures. Hydrogen gas flowing through the core then becomes superheated and exits the engine at very high exhaust velocities. Click here (54K) for a schematic of the engine. The combination of temperature and the low molecular weight of hydrogen will produce an engine with specific impulses above 900 seconds. This is almost twice the performance of the LOX/hydrogen space shuttle engines. Nuclear rocket engines were designed, built and tested in the 1960s but were never implemented into the space program.

Solid Core Nuclear Rockets--Rover/NERVA

The US government began the Rover program in 1956 at the Los Alamos Scientific Laboratory to develop a nuclear reactor suitable for operation as a nuclear rocket. In 1963, the Nuclear Engine for Rocket Vehicle Applications, NERVA, program was started to take the graphite based reactor built at Los Alamos and create a functioning rocket engine. The programs ran in parallel and involved Los Alamos, Westinghouse, Aerojet, and other industrial partners. The final engine tested used a core made of graphite rods 54 inches long, hexagonal in cross section with 0.75 inches across the flats, and with 19 holes running the full length of the rod. Click here (110K) for a schematic of a fuel element. The rod was a mixture of uranium/zirconium/carbide in a graphite matrix. Each flow hole was independently orificed to match the heat generation levels.

During the years from 1956 to termination in 1971, the programs accomplished the following records:

1) Highest power - 4500 megawatts thermal power

2) 5500 degress Fahrenheit exhaust temperature

3) 250,000 pounds thrust

4) 850 seconds of specific impulse

5) 90 minutes of burn time

6) thrust to weight ratios of 3 to 4

In all, 23 tests were conducted at the Nevada Test Site at the Nuclear Rocket Development Station, NRDS.

Here is an artist's concept of a nuclear powered Mars ship (15K)

Gas Core Nuclear Rocket -- GCNR

The GCNR is a concept which was also experimentally investigated in the 1960s during the Rover program. The idea is to use a gaseous nuclear fuel instead of the solid graphite core used in NERVA. A gaseous fuel could attain tempertures of several tens of thousands of degrees which would allow specific impulses of 3000 to 5000 seconds to be considered. Such an engine would allow manned missions to Mars to be accomplished in a few months each way. Currently, research into the GCNR concept is underway at the Los Alamos National Laboratory under a program from the NASA Marshall Space Flight Center. Some of the research problems that are being studied are:

1) Can a stable vortex of hot (5 eV) uranium plasma be created and maintained?

2) How is the uranium injected into the hot plasmoid during operation to make-up losses?

3) How can we reduce the heat load on the wall of the chamber? Current goals are to withstand 100 megawatts per square meter.

4) Is hydrogen the best propellant?

Here are 3 schematics (33K) showing how a Gas Core Nuclear Rocket might work.

The results of computational modeling during 1997 indicate the the counterflow toroid concept, #3 in the figures, has the best chance for stability and performance. Research is continuing.

Here is a newly published paper Reducing the Risk to Mars: the Gas Core Nuclear Rocket that shows more details of the mission comparisons with the NASA design reference mission. This is in html format to read here. The latest engine geometry look slike this:



Technical Papers

Some technical papers (requires Acrobat reader) on nuclear rocket technology can be found here:

Nuclear Thermal Rocket for a Manned Mars Mission is a paper on using solid core nuclear rocket, ala Rover/NERVA, for a Mars Mission-- ship masses, delta Vs, etc.

Reducing the Risk to Mars: the Gas Core Nuclear Rocketa paper on the counter flow toroidal concept for a gas core rocket.

SAFE Testing Nuclear Rockets Economically Novel technique to test a nuclear rocket in today's environment at full power and full duration for less than $20 M

High Energy Density Propulsion: Reducing the Risk to Humans in Planetary Propulsion - a look at what is technically possible in the next decade using nuclear propulsion

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