Engineering For Success

Courtesy of LANL/NCERC
Courtesy of LANL/NCERC
Courtesy of LANL/NCERC

SpaceNukes power systems are designed to provide high confidence in meeting performance and lifetime specifications. We use our expertise to balance the desire for low mass with the realities associated with successfully engineering, launching, and operating a power system in space. We ensure that the system can be constructed and launched within cost and schedule, and that is can operate reliably once it is deployed. Our confidence is derived from the technical and programmatic success of the KRUSTY project, as well as the attributes listed below.

Simple Operation and Control: The most innovative and unique feature of SpaceNukes power systems is simplicity in dynamic operation and control, which is extremely important for operation in space. Other than KRUSTY, all fission power systems that have ever operated (worldwide and in previously space) required at least two real-time, autonomous reactor control systems: one for reactivity control and another for coolant flow control. SpaceNukes reactors do not require either! We tailor our concepts to use nuclear and thermal physics in a way that provides reactor self regulation, as was demonstrated in the KRUSTY nuclear system test. The reactor inherently adjusts to provide the thermal power draw of  the power conversion system, without any reactor control; including the ability to survive a total loss of heat removal without overheatingIn addition to ensuring robust and reliable operation in space, the lack of autonomous reactor control greatly reduces system cost and complexity. It eliminates the need for the development and integration of numerous instrumentation, control, and software components. The ability to provide reliable reactor diagnostics in space, for years with no maintenance, is unproven - thus SpaceNukes reactors are designed not to rely upon them. Simple and predictable dynamics also simplifies regulatory approvals, and more so minimizes (and potentially eliminates) the need for nuclear system testing.

Robust and Reliable: SpaceNukes power systems are designed for high  reliability via simplicity and redundancy. Failure mechanisms are limited due to the relatively few reactor components: no pumps, valves, filters, coolant freeze/thaw systems, autonomous control components, systems, and software, etc. In addition, SpaceNukes reactors are designed to keep fuel burn-up low enough (via high fuel fraction and low power peaking)that typical reactor issues like fission gas release and fuel swelling are insignificant. The other aspect of high reliability is redundancy. SpaceNukes power systems can provide full power even with the failure of multiple Stirling “strings”; a string includes the heat pipe, coupling hardware, the converter, and the controller. Note that the inclusion of this redundancy reduces the rated power of the system by ~33%, although the system could potentially be operated at higher power until a failure was diagnosed. Most importantly, robust operation and tolerance to worst case system failures/ upsets was demonstrated during the KRUSTY nuclear system test.

Simplified Launch Approval and ATLO: All SpaceNukes reactors are radiologically benign prior to launch and are designed to remain inherently subcritical during all possible launch accidents (e.g. flooded with water, surrounded by sand, etc.). Assembly, Test, Launch Operations (ATLO) are also simplified by the robust criticality safety features, and as well as the small number of system components and the ability to electrically test the flight unit.