MSR Radiator 1 Radiator 1 1 Introduction The reactor generates excess power because of the inefficiencies in converting the core s thermal power into electricity The goal of the radiator group was to design a lightweight radiator that would dissipate the excess power from the MSR operating on either the Lunar or Martian surface This section will step through the process of choosing the radiator design and then present a detailed analysis of the chosen radiator First there is an overview of the specific requirements based on our proposed mission and the objectives agreed upon by the entire design team Next is an examination of the different radiator concepts that the group considered with analysis of the important facets of each The radiator group used decision methodology to determine the concepts that it would use in the design the third section breaks down this decision making process and explains the results Based on the conclusions of the concept analysis the fourth section describes the design the group chose and explores its important aspects The following section contains a summary of the analyses and calculations that the group performed in order to select and verify various parameters of the design Finally the sixth section will discuss ideas for future work 1 1 1 Design Requirements From the overall MSR design goals see Section X X the radiator group created a set of more specific requirements These requirements pertain to how the radiator interacts with the other systems and the environment From the systems side consider how the radiator fits into the sequence of events from launch to surface operation first it must fit into the launch vehicle along with the other reactor components This means that not only must there be sufficient contiguous volume but also the weight of the radiator when added to the weight of the rest of the reactor must not exceed the available launch capacity This requirement necessitates give and take between the various design groups to arrive at the optimal parameters Second the radiator must be able to withstand the large g forces and vibrations associated with launch and landing without damaging itself or neighboring components Third the radiator must be in a configuration where it operates correctly after landing Whether or not there is unpacking required after the lander positions the reactor the radiator must be able to mate with the other systems and operate when the startup command is given This dictates consideration of the linkages between the radiator and the other components and its role in the reactor startup procedure Using the same sequence of events the design team generated the environmental requirements It is likely the radiator will contact the Earth s atmosphere when it is first constructed and packaged into the rocket The design must ensure that the high atmospheric pressure compared to its destinations does not damage any components and chemicals present in the air do not corrode or contaminated its surfaces Next during 1 MSR Radiator the rocket s transit from Earth to either the Moon or Mars the radiator will experience a low gravity environment and be subject to direct radiation from the sun Once the radiator lands on the surface the design must take into consideration the effects of gravity temperatures in the range of 100 400 K and material reactivity with the atmosphere and soil In addition since the radiator will begin to operate it is important to asses how operation interacts with the planetary environment 1 1 2 Scope With only the design goals and constraints given above this is still a very open design question The design team tailored the scope of the radiator design to a manageable set of design considerations Here we will describe what design aspects the team specifically investigated and which merit further analysis Integration of the radiator with the other systems is critical in the creation of an overall tenable design for the MSR To this end the radiator group worked closely with the power conversion group which in turn collaborated with the core group to ensure that the three systems interfaced appropriately and to verify that the choices made by the radiator team met the entire design team s requirements Communication with the other groups was important for balancing mass and size issues and creating a geometry that complimented the rest of the system However since the design of the lander and all the physical requirements of the assembly are beyond the scope of this investigation this group did not consider exact methods of attachment and construction The environment is also a critical factor in our design since the peculiarities of the Martian and Lunar surface conditions control the effectiveness of a radiator The design group brought the major environmental factors into consideration by taking into account the physical conditions on the Lunar and Martian surfaces including meteorological conditions temperature swings and chemical composition of the atmosphere and soil See Appendix X for a detailed discussion of the Martian and Lunar environments In particular the design team evaluated the important chemical interactions that could occur on exposed surfaces Since it is beyond the scope of this project to determine the landing sites for the reactor in general the group used average planetary conditions when doing these analyses In order to gauge the efficacy of our design choices the radiator group performed analyses to calculate the interactions between the radiator and the other systems as well as interactions within the radiator system itself Thermal transfer analyses are important for gauging the operational efficiency of the system and ensuring components perform as predicted In addition the radiator group performed calculations validating the mechanical structure taking into account the physical stresses imposed by the other systems and the environment For this investigation most of these analyses considered steady state thermo physical conditions to reduce the computational load The purpose of this design project is to deliver a physical design but not one exacting enough to permit construction For example it is beyond the scope of the team s analyses 2 MSR Radiator to determine exact methods of assembly selection of parts or electromechanical operation Given that such technology is possible and the design is logical and meets all the other requirements the design team left these finer details