1 Radiator1.1 Introduction1.1.1 Goals1.1.2 Design Requirements1.1.3 Scope1.2 Radiator Options1.2.1 Helium-Fed Radiator1.2.2 SNAP-21.2.3 SNAP-10A1.2.4 Liquid Droplet Radiator1.2.5 Liquid Sheet Radiator1.2.6 SAFE-4001.2.7 SP-1001.3 Concept Choice1.3.1 Litmus Tests1.3.2 Extent-to-Which Tests1.3.3 Choice Analysis1.3.4 Decision1.4 Radiator Design1.4.1 Design Parameters1.4.2 Design Constraints1.4.3 Design1.4.4 Summary of Parameters1.5 Design Analysis1.5.1 Size and Mass Analysis1.5.2 Design Comparison1.5.3 Accident analysis1.6 Future Work1.6.1 Extensions1.6.2 Transient Analysis1.6.3 Future Projects1.7 Conclusions1.7.1 ReferencesMSR - Radiator1 Radiator1.1 IntroductionThe power conversion system dealt with transforming the reactor’s thermal energy intoelectricity. This electricity is the purpose of the entire reactor system, but because thepower conversion system is not one hundred percent efficient, the reactor will need togenerate excess thermal power. Therefore, goal of the radiator subgroup was to design aradiator that would dissipate the excess power from a fission reactor located on thesurface of the Moon or Mars. This section will step through the process of choosing the radiator design and detail howthat design functions. First, there is an overview of the specific requirements, based onour proposed mission and the objectives agreed upon by the entire design team. Next isan examination of the different radiator concepts that the group considered, with analysisof the important facets of each. The radiator subgroup used decision methodology todetermine the concepts that it would use in the design; the third section breaks down thisdecision making process and explains the results. Based on the conclusions of the conceptanalysis, the fourth section describes the design the subgroup chose and explores itsimportant aspects. The following section contains a summary of the analyses andcalculations that the group performed in order to select and verify various parameters ofthe design. Finally, the sixth section will discuss ideas for future work. 1.1.1 GoalsThe radiator design must take into account the five main programmatic goals for thisdesign project: 100 kWe, 5 EFPY, safe operation, meets environmental regulations, andworks on the Moon and Mars. All of these criteria have implications for the radiator’sdesign parameters, and the radiator subgroup has embodied this in the decisions madethroughout the design. First, the 100 kWe requirement, combined with the efficiency anddesign of the power conversion system, dictates the amount of waste heat that the reactorwill generate, and in what form that energy arrives at the radiator system. Next, thedesign team had to ensure that the design was robust enough to sustain five years ofcontinuous operation. The safety and environmental protection guidelines required thegroup evaluate carefully the impact of the radiator’s operation on the environment duringboth routine and abnormal conditions. Finally, any design the group considers must beable to function on the Moon and Mars, which requires a constant consideration of theproperties of both environments. 1.1.2 Design RequirementsFrom the overall design goals, the radiator subgroup created a set of more specificrequirements. These requirements pertain to how the radiator interacts with the othersystems and the environment. From the systems side, consider how the radiator fits into- 1 -MSR - Radiatorthe sequence of events from launch to surface operation; first, it must fit into the launchvehicle along with the other reactor components. This means that not only must there besufficient contiguous volume, but also the weight of the radiator must not exceed theavailable launch capacity. This requirement necessitates give and take between thevarious design subgroups to arrive at the optimal parameters. Second, the radiator mustbe able to withstand the large g-forces and vibrations associated with launch and landingwithout damaging itself or neighboring components. Third, the radiator must be in aconfiguration where it operates correctly after landing. Whether or not there is unpackingrequired after the lander positions the reactor, the radiator must be able to mate with theother systems and operate when the startup command is given. This dictates considerationof the linkages between the radiator and the other components and its role in the reactorstartup procedure.Using the same sequence of events, the design team generated the environmentalrequirements. It is likely the radiator will contact the Earth’s atmosphere when it is firstconstructed and packaged into the rocket. The design must ensure that the highatmospheric pressure (compared to its destinations) does not damage any components,and chemicals present in the air do not corrode or contaminated its surfaces. Next, duringthe rocket’s transit from Earth to either the Moon or Mars, the radiator will experience amicrogravity environment and temperatures around zero Kelvin. Once the radiator landson the surface of the Moon or Mars, the design team again must take into considerationgravity and chemical reactions with the atmosphere and soil. In addition, since theradiator will begin to operate, it is important to asses how operation interacts with theplanetary environment.1.1.3 ScopeWith only the design goals and constraints given above, this is still a very open designquestion. In order to make the radiator design team’s work efficient, the range ofconsiderations was limited, and it is important to understand what aspects the teamconsidered, and which merit further analysis. The primary considerations were that thedesign met the five goals outlined above, and fulfilled the other design requirements asfully as possible. In addition, several other primary considerations drove the radiatorsubgroup’s reasoning. The integration of the radiator with the other systems is critical in the creation of anoverall tenable design for the MSR. To this end, the radiator subgroup worked closelywith the power conversion subgroup to ensure that the two systems interfacedappropriately, and to verify that the choices made by the radiator team met both groups’requirements. Communication with the other groups was important