Systems for Nuclear Auxiliary Power
The SNAP program developed as a result of Project Feedback, a Rand Corporation study of reconnaissance satellites completed in 1954.
The other project used nuclear reactors to generate energy, and was developed by the Atomics International Division of North American Aviation.
[2]: 5 Most of the systems development and reactor testing was conducted at the Santa Susana Field Laboratory, Ventura County, California using a number of specialized facilities.
[citation needed] SNAP-1 was a test platform that was never deployed, using cerium-144 in a Rankine cycle with mercury as the heat transfer fluid.
They had a liquid NaK thermal control system and a movable shutter to dump excess heat.
[13] In general, the SNAP 11 fuel block is a cylindrical multi-material unit which occupies the internal volume of the generator.
Capsule is surrounded by a platinum sphere, approximately 2+1⁄4 inches in diameter, which provides shielding and acts as an energy absorber for impact considerations.
This assembly is enclosed in graphite and beryllium sub-assemblies to provide the proper thermal distribution and ablative protection.
Fueled with plutonium-238, two parallel lead telluride thermocouple generators produced an initial maximum of approximately 30 watts of electricity.
[19] A SNAP-19C was used to power a telemetry array at Nanda Devi in Uttarakhand for a CIA operation to track Chinese missile launches.
The energy source for each device was a rod of plutonium-238 providing a thermal power of approximately 1250 W.[23] This fuel capsule, containing 3.8 kilograms (8.4 lb) of plutonium-238 in oxide form (44,500 Ci or 1.65 PBq), was carried to the Moon in a separate fuel cask attached to the side of the Lunar Module.
The fuel cask from the SNAP-27 unit carried by the Apollo 13 mission currently lies in 20,000 feet (6,100 m) of water at the bottom of the Tonga Trench in the Pacific Ocean.
[25] A series of compact nuclear reactors intended for space use, the even numbered SNAPs were developed for the U.S. government by the Atomics International division of North American Aviation.
The SER used uranium zirconium hydride as the fuel and eutectic sodium-potassium alloy (NaK) as the coolant and operated at approximately 50 kW thermal.
The basic concept was that nuclear power would be a long term source of energy for crewed space capsules.
Cracks in the shield material would be fatal to any space crew or payload depending on it because it would allow radiation to stream through to the crew/payload compartment.
Analysis also revealed that under thermal and radiation gradients, the lithium hydride could disassociate and hydrogen ions could migrate through the shield.
[citation needed] The SNAP-8 reactors were designed, constructed and operated by Atomics International under contract with the National Aeronautics and Space Administration.
The SNAP 8 design included primary and secondary NaK loops to transfer heat to the mercury rankine power conversion system.
[29][30] It was built as a research project for the Air Force, to demonstrate the capability to generate higher power than RTGs.
[citation needed] SNAP-10A was launched into Earth orbit in April 1965, and used to power an Agena-D research satellite, built by Lockheed/Martin.
