Titanium-Water Heat Pipe Radiator for Spacecraft Fission Power, Phase II

The immediate NASA application is for space fission nuclear reactors that utilize Stirling converters or thermoelectrics for power conversion. NASA Glenn Research Center is currently developing a 1kWe Fission Power System with a 15 year design life that could be available for a 2020. An electrically heated test of the complete reactor/energy conversion system (except for the titanium/water heat pipes) is planned for in the next few years test. This test will use an electrically heated depleted uranium core, and will help validate the overall system design. The next step will be to life test the complete system, from the electrically heated uranium core to the titanium/water heat pipes. ACT will design, fabricate, and test the titanium/water heat pipes for the Kilopower life test on the proposed program. At the end of the Phase II program, these heat pipes will be delivered to NASA Glenn Research Center. Assuming that the Phase II program is successful, ACT then plans to assist in the Kilopower life test on a Phase III program. One application is for satellite thermal control for military and commercial customers. As satellite powers continue to increase, the required radiator panel size and mass must also increase. Since the radiator size scales with T^4, switching from ammonia to water heat pipes would increase the allowable temperature, and significantly reduce the radiator size. In addition to large (communications) satellites, SmallSats and CubeSats could also benefit from scaled down heat pipes developed on the proposed program. CubeSats are made up of 10 cm x 10 cm x 10 cm units, and titanium/water heat pipes can simplify ground testing. There are three disadvantages of CCHPs for CubeSats: (1) They are relatively expensive, (2) They are relatively massive, and designed to carry heat over several meters, (3) Orientations during Thermal Vacuum testing are constrained by the heat pipes. In contrast, the titanium water heat pipes developed on the current program can be scaled down so that they are small, low mass, and relatively cheap. They can also be tested in any orientation, and can be embedded in High Conductivity (HiK™) aluminum plates, to give a high conductivity baseplate that is extremely inexpensive compared to pyrolytic graphite. More »