Pewee-1 was a nuclear reactor, designed and built as part of the Rover program, specifically to investigate the performance characteristics of a small reactor for nuclear propulsion in space. Peewee used both NbC- (niobium carbide) and ZrC- (zirconium carbide) coated fuel elements, and it was found that the ZrC-coated elements resisted corrosion by hydrogen more effectively than the NbC coating. Strutural integrity remained a problem as it had been with some other reactors in the Rover program. Pewee was tested in the autumn of 1968, achieving 514 megawatts of power for 2,400 seconds.

 

Other reactors developed during the Rover program were KIWI, Phoebus, and Nuclear Furnace 1.

 

Pewee-1 performance parameters
reactor power (MW)	514
flow rate (kg/s)	18.6
fuel exit temp (K)	2,556
chamber temp (K)	1,837
chamber pressure (MPa)	4.28
core inlet temp (K)	128
core inlet pressure (MPa)	5.56
reflector inlet temp (K)	79
reflector inlet pressure (MPa)	5.79
periphery & structural flow (kg/s)	6.48