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 TestSmall Mass and SizeControllabilityLaunchable/Accident SafeHigh Reliability/Limited Maintenance1.3.3 Choice Analysis1.3.4 Decision1.4 Radiator Design1.4.1 Design ParametersConciderations1.4.2 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 Analysis1.7 Conclusions1.7.1 ReferencesMSR - Radiator1 Radiator1.1 IntroductionDue to inefficiencies in the power conversion unit, the reactor must generate extra heat,waste heat, which the radiator system must dissipate to prevent meltdown of the entiresystem. The goal of the radiator group was to design a lightweight radiator that woulddissipate the excess power from the MSR operating on either the Lunar or Martiansurface. This section will step through the process of choosing the radiator design andthen present a detailed analysis of the chosen radiator. First, there is an overview of the specific requirements, based on our proposed missionand the objectives agreed upon by the entire design team. Next is an examination of thedifferent radiator concepts that the group considered, with analysis of the important facetsof each. The radiator group used decision methodology to determine the concepts that itwould use in the design; the third section breaks down this decision making process andexplains the results. Based on the conclusions of the concept analysis, the fourth sectiondescribes the design the group chose and explores its important aspects. The followingsection contains a summary of the analyses and calculations that the group performed inorder to select and verify various parameters of the design. Finally, the sixth section willdiscuss 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 group has embodied this in the decisions madethroughout the design. First, the 100 kWe requirement, combined with the efficiency and design of the powerconversion system, dictates the amount of waste heat that the reactor will generate, and inwhat form that energy arrives at the radiator system. Through much collaboration andcompromise with the power conversion unit, the selected PCU efficiency target was set atten percent. In this particular system, given the 10% PCU efficiency, the radiator mustdissipate 900kWth for a 100kWe system, and Next, the design team had to ensure thatthe design was is robust enough to sustain five years of continuous operation. Next, Tthe safety and environmental protection guidelines required the group evaluatecarefully the impact of the radiator’s operation on the environment during both routineand abnormal conditions. In this case, the major safety and environmental threat is failureof a sufficient percentage of the radiator system to cause a core meltdown. Finally, anydesign the group considers must be able to function on the Moon and Mars, whichrequires a constant consideration of the properties of both environments. - 1 -MSR - Radiator1.1.2 Design RequirementsFrom the overall design goals, the radiator group 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 intothe 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, when added to theweight of the rest of the reactor, must not exceed the available launch capacity. Thisrequirement necessitates give and take between the various design groups to arrive at theoptimal parameters. Second, the radiator must be able to withstand the large g-forces andvibrations associated with launch and landing without damaging itself or neighboringcomponents. Third, the radiator must be in a configuration where it operates correctlyafter landing. Whether or not there is unpacking required after the lander positions thereactor, the radiator must be able to mate with the other systems and operate when thestartup command is given. This dictates consideration of the linkages between theradiator and the other components and its role in the reactor startup 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, temperature (100-400K) and chemical material reactions reactivity with theatmosphere and soil. In addition, since the radiator will begin to operate, it is important toasses how operation interacts with the planetary 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, theThe range designteam tailored the scope of the radiator design to a manageable set of designconsiderations. of considerations was limited, and it is important to Here we will describeunderstand what design aspects the team considered, and which merit further analysis.The primary considerations were that the design met the five