An issue with nuclear thermal rockets (NTRs) is that they need to be hot. The hotter they are the more efficient they are. The limitation is the reactor chamber which has a melting point. The concept of the gas core nuclear rocket (GCNR) is that the reactor has already melted. This allows very hot temperatures in the reactor. However, the issue is then containing the fissioning material which is not an easy task.
Open cycle GCNRs are very efficient but the fission material is not confined for very long. This causes the fission material to shoot into space at high velocity before it can be all used. This is sub optimal for both financial and environmental reasons. Closed cycle GCNRs barely manage to contain the fission material but lose a lot of exhaust velocity in the process.
Last Updated 15/6/22
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