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Light-Weight Radioisotope Heater Unit

Description: DOE is developing a new generation of radioisotope-fueled 1-watt heaters, for initial use on NASA's upcoming Galileo and International Solar-Polar Missions. Each heater must contain passive safety provisions to ensure fuel retention under all credible accident conditions. Initial design reviews raised some concern about the accuracy of the predicted peak reenetry temperature, and about the adequacy of the safety margin under certain unlikely - but not impossible-reentry modes. Of particular concern was the possile release of the accumulated helium inventory from the fuel during the reentry heat pulse, and the potential effect of enhanced heat conduction due to helium buildup in gaps. The latter problem had not been addressed in previous studies. Fairchild carried out a large number of reentry thermal analyses to resolve the analytical uncertainties, and proposed design changes to reduce the thermal coupling between the aeroshell and the fuel capsule. For the computed reentry temperature history of the modified design, the rate of helium buildup in the gaps was analyzed. The analysis accounted for temperature-dependent helium diffusion through the fuel pellet and for leakage to space through the permeable aeroshell. It showed that most of the helium inventory leaves the fuel during reentry, but that it never reaches a continuum pressure in the gaps, and therefore has no significant thermal effect. Under these conditions, the Fairchild-modified design provides ample safety margin against clad failure, even for very unlikely reenty trajectories. The modified design was successfully vibration-tested and was subsequently adopted by the project. Cross Reference CID #8517. There are two copies in the file.
Date: April 1, 1981
Creator: Schock, Alfred
Partner: UNT Libraries Government Documents Department

Mars Rover RTG Study

Description: This report summarizes the results of a Radioisotope Thermoelectric Generator (RTG) design study conducted by Fairchild Space Company at the direction of the U.S. Department of Energy's Office of SpecialApplications, in suppport of the Mars Rover and Sample Return mission under investigation at NASA's Jet Propulsion Laboratory. The report is a rearranged, updated, and significantly expanded amalgam of three interrelated papers presented at the 24th Intersocity Energy Conversion Engineering Conference (IECEC) at Arlington, Virginia, on August 10, 1989.
Date: August 25, 1989
Creator: Schock, Alfred
Partner: UNT Libraries Government Documents Department

Mars Rover RTG Study

Description: This report summarizes the results of a Radioisotope Thermoelectric Generator (RTG) design study conducted by Fairchild Space Company at the direction of the U.S. Department of Energy's Office of Special Applications, in support of the Mars Rover and Sample Return mission under investigation at NASA's Jet Propulsion Laboratory. Presented at the 40th Congress of the IAF, Oct. 7-13, 1989 in Torremolinos, Malaga-Spain. The paper describes the design and analysis of Radioisotope Thermoelectric Generators (RTGs) for powering the Mars Rover vehicle, which is a critical element of the unmanned Mars Rover and Sample Return mission (MRSR). The RTG design study was conducted by Fairchild Space for the U.S. DOE in support of the JPL MRSR Project. The paper briefly describes a reference mission scenario, an illustrative Rover design and activity pattern on Mars, and its power system requirements and environmental constraints, including the RTG cooling requirements during transit to Mars. It summarizes the baseline RTG's mass breakdown, and presents a detailed description of its thermal, thermoelectric, and electrical analysis. The results presented show the RTG performance achievable with current technology, and the performance improvements that would be achievable with various technology developments. It provides a basis for selecting the optimum strategy for meeting the Mars Rover design goals with minimal programmatic risk and cost. Cross Reference CID #7135 dated 10/1989. There is a duplicate copy. This document is not relevant to the OSTI Library. Do not send.
Date: November 27, 1989
Creator: Schock, Alfred
Partner: UNT Libraries Government Documents Department

Mars Rover RTG Study

Description: Presented at the 40th Congress of the IAF, Oct. 7-13, 1989 in Torremolinos, Malaga-Spain. The paper describes the design and analysis of Radioisotope Thermoelectric Generators (RTGs) for powering the Mars Rover vehicle, which is a critical element of the unmanned Mars Rover and Sample Return mission (MRSR). The RTG design study was conducted by Fairchild Space for the U.S. DOE in support of the JPL MRSR Project. The paper briefly describes a reference mission scenario, an illustrative Rover design and activity pattern on Mars, and its power system requirements and environmental constraints, including the RTG cooling requirements during transit to Mars. It summarizes the baseline RTG's mass breakdown, and presents a detailed description of its thermal, thermoelectric, and electrical analysis. The results presented show the RTG performance achievable with current technology, and the performance improvements that would be achievable with various technology developments. It provides a basis for selecting the optimum strategy for meeting the Mars Rover design goals with minimal programmatic risk and cost. There is a duplicate copy and three copies in the file.
Date: October 1, 1989
Creator: Schock, Alfred
Partner: UNT Libraries Government Documents Department

MITG Test Plan

Description: The plan presented is for the testing of a prototypical slice of the Modular Isotopic Thermoelectric Generator (MITG). Cross Reference T48-1.
Date: August 1, 1981
Creator: Eck, Marshall B.
Partner: UNT Libraries Government Documents Department

Modular Isotopic Thermoelectric Generator

Description: Advanced RTG concepts utilizing improved thermoelectric materials and converter concepts are under study at Fairchild for DOE. The design described here is based on DOE's newly developed radioisotope heat source, and on an improved silicon-germanium material and a multicouple converter module under development at Syncal. Fairchild's assignment was to combine the above into an attractive power system for use in space, and to assess the specific power and other attributes of that design. The resultant design is highly modular, consisting of standard RTG slices, each producing ~24 watts at the desired output voltage of 28 volt. Thus, the design could be adapted to various space missions over a wide range of power levels, with little or no redesign. Each RTG slice consists of a 250-watt heat source module, eight multicouple thermoelectric modules, and standard sections of insulator, housing, radiator fins, and electrical circuit. The design makes it possible to check each thermoelectric module for electrical performance, thermal contact, leaktightness, and performance stability, after the generator is fully assembled; and to replace any deficient modules without disassembling the generator or perturbing the others. The RTG end sections provide the spring-loaded supports required to hold the free-standing heat source stack together during launch vibration. Details analysis indicates that the design offers a substantial improvement in specific power over the present generator of RTGs, using the same heat source modules. There are three copies in the file.
Date: April 3, 1981
Creator: Schock, Alfred
Partner: UNT Libraries Government Documents Department

Modular Isotopic Thermoelectric Generator

Description: Advanced RTG concepts utilizing improved thermoelectric materials and converter concepts are under study at Fairchild for DOE. The design described here is based on DOE's newly developed radioisotope heat source, and on an improved silicon-germanium material and multicouple converter module under development at Syncal. Fairchild's assignment was to combine the above into an attractive power system for use in space, and to assess the specific power and other attributes of that design.
Date: January 1, 1981
Creator: Schock, Alfred
Partner: UNT Libraries Government Documents Department

Modular Isotopic Thermoelectric Generator (MITG) Design and Development, Part A-E. Original was presented at 1983 Intersociety Energy Conversion Engineering Conference (IECEC)

Description: Advanced RTG concepts utilizing improved thermoelectric materials and converter concepts are under study at Fairchild for DOE. The design described here is based on DOE's newly developed radioisotope heat source, and on an improved silicon-germanium material and a multicouple converter module under development at Syncal. Fairchild's assignment was to combine the above into an attractive power system for use in space, and to assess the specific power and other attributes of that design. The resultant design is highly modular, consisting of standard RTG slices, each producing 24 watts at the desired output voltage of 28 volt. Thus, the design could be adapted to various space missions over a wide range of power levels, with little or no redesign. Each RTG slice consists of a 250-watt heat source module, eight multicouple thermoelectric modules, and standard sections of insulator, housing, radiator fins, and electrical circuit. The design makes it possible to check each thermoelectric module for electrical performance, thermal contact, leaktightness, and performance stability, after the generator is fully assembled; and to replace any deficient modules without disassembling the generator or perturbing the others. The RTG end sections provide the spring-loaded supports required to hold the free-standing heat source stack together during launch vibration. Detailed analysis indicates that the present generation of RTGs, using the same heat source modules. There is a duplicate copy of this document. OSTI has a copy of this paper.
Date: April 29, 1983
Creator: Schock, A.
Partner: UNT Libraries Government Documents Department

Design and Structural Analysis of Mars Rover RTG

Description: The paper describes the design and the structural and mass analysis of a Radioisotope Thermoelectric Generators (RTGs) for powering the MARS Rover vehicle, which is a critical element of the unmanned Mars Rover and Sample Return mission (MRSR). The RTG design study was conducted by Fairchild Space Company for the U.S. Department of Energy, in support of the Jet Propulsion Laboratory's MRSR project.; The paper briefly describes a reference mission scenario, an illustrative Rover design and activity pattern on Mars, and its power system requirements and environmental constraints, including the RTG cooling requirements during transit to Mars. It identifies the key RTG design problem, i.e. venting the helium generated by the fuel's alpha decay without intrusion of the Martian atmosphere into the RTG, and proposes a design approach for solving that problem.; Using that approach, it describes a very conservative baseline RTG design. The design is based on the proven and safety-qualified General Purpose Heat Source module, and employs standard thermoelectric unicouples whose reliability and performance stability has been extensively demonstrated on previous space missions. The heat source of the 250-watt RTG consists of a stack of 18 separate modules that is supported at its ends but not along its length. The paper describes and analyzes the structure that holds the stack together during Earth launch and Mars operations but allows it to come apart in case of an inadvertent reentry.; A companion paper presented at this conference describes the RTG's thermal and electrical analysis, and compares its performance with that of several lighter but less conservative design options.; There is a duplicate copy in the ESD files. This document is not relevent to OSTI Library. Do not send.
Date: September 29, 1989
Creator: Schock, Alfred; Hamrick, T.; Sankarankandath, V. & Shirbacheh, M.
Partner: UNT Libraries Government Documents Department

Design of Isotope Heat Source for Automatic Modular Dispersal During Reentry, and Its Integration with Heat Exchangers of 6-kWe Dynamic Isotope Power System

Description: In late 1986 the Air Force Space Division (AF / SD) had expressed an interest in using a Dynamic Isotope Power System (DIPS) of approximately 6-kWe to power the Boost Surveillance and Tacking System (BSTS) satellites. In support of that objective, the U.S. Department of Energy (DOE) requested Fairchild Space Company to perform a conceptual design study of the DIPS heat source and of its integration with the dynamic power conversion system, with particular emphasis on system safety. This paper describes the results of that study. The study resulted in a design for a single heat source of ~30-kWt, employing the standard 250-W General Purpose Heat Source (GPHS) modules which DOE had previously developed and safety-tested for Radioisotope Thermoelectric Generators (RTS's)
Date: January 1, 1989
Creator: Schock, Alfred
Partner: UNT Libraries Government Documents Department

Structural, Thermal, and Safety Analysis of Isotope Heat Source and Integrated Heat Exchangers for 6-kWe Dynamic Isotope Power System (DIPS)

Description: The design of the 30-kWt isotope heat source integrated with a Rankine boiler and a Brayton gas heater, which was described in the preceding paper in these proceedings, was subjected to structural, thermal, and safety analyses. The present paper describes and discusses the results of these analyses. Detailed structural analyses of the heat source integrated with the boiler and gas heater showed positive safety margins at all locations during the launch. Detailed thermal analyses showed acceptable temperatures at all locations, during assembly, transfer and orbital operations. Reentry thermal analyses showed that the clads have acceptable peak and impact temperatures. Loss-of-cooling analyses indicated the feasibility of a passive safety concept for preventing over temperatures. Static structural analysis showed positive safety margins at all locations, and dynamic analysis showed that there were no low-frequency resources. Continuum-mechanics code analyses of the effects of the impact of Solid Rocket Booster (SRB) fragments on the heat source and of the very unlikely impact of the full heat source on concrete indicated relatively modest fuel clad deformations and little or no fuel release.
Date: January 1, 1989
Creator: Schock, Alfred
Partner: UNT Libraries Government Documents Department

Thermal and Electrical Analysis of MARS Rover RTG, and Performance Comparison of Alternative Design Options.

Description: The paper describes the thermal, thermoelectric and electrical analysis of Radioisotope Thermoelectric Generators (RTGs) for powering the MARS Rover vehicle, which is a critical element of the unmanned Mars Rover and Sample Return mission (MRSR). The work described was part of an RTG design study conducted by Fairchild Space Company for the U.S. Department of Energy, in support of the Jet Propulsion Laboratory's MRSR Project.; A companion paper presented at this conference described a reference mission scenario, al illustrative Rover design and activity pattern on Mars, its power system requirements and environmental constraints, a design approach enabling RTG operation in the Martian atmosphere, and the design and the structural and mass analysis of a conservative baseline RTG employing safety-qualified heat source modules and reliability-proven thermoelectric converter elements.; The present paper presents a detailed description of the baseline RTG's thermal, thermoelectric, and electrical analysis. It examines the effect of different operating conditions (beginning versus end of mission, water-cooled versus radiation-cooled, summer day versus winter night) on the RTG's performance. Finally, the paper describes and analyzes a number of alternative RTG designs, to determine the effect of different power levels (250W versus 125W), different thermoelectric element designs (standard versus short unicouples versus multicouples) and different thermoelectric figures of merit (0.00058K(superscript -1) to 0.000140K (superscript -1) on the RTG's specific power.; The results presented show the RTG performance achievable with current technology, and the performance improvements that would be achievable with various technology developments. It provides a basis for selecting the optimum strategy for meeting the Mars Rover design goals with minimal programmatic risk and cost.; There is a duplicate copy and also a duplicate copy in the ESD files.
Date: September 29, 1989
Creator: Schock, Alfred; Or, Chuen T & Skrabek, Emanuel A
Partner: UNT Libraries Government Documents Department

On the Nature of the Distortion of a GPHS Fueled Capsule Impacted on Various Media at Various Velocities and Under Various Boundary Conditions; Appendix F: Response of the GPHS Module to LH(Sub-2)-LO(Sub-2) Overpressure in Various Shielded and Unshielded Geometries

Description: This body of work represents the parametric investigation of conditions of impact for a GPHS fueled capsule.
Date: August 25, 1987
Creator: Eck, Marshall B & Mukunda, Meera
Partner: UNT Libraries Government Documents Department

On the Nature of the Response of the General Purpose Heat Source to the Impact of Large Solid Rocket Motor Casing Fragments

Description: After the Challenger (STS-51L)accident new tests were performed to assess the response of the GPHS module to large fragment impacts. The subject of this paper is the analytical process used to perform macro calibrations of the analytical methods and their application to predict the GPHS modules' response to serially increasing levels of test environment complexity. Sensitivity studies were performed to generate a fueled-clad-distortion-response statistical database for use in a Monte Carlo based fuel release analysis. The analyses showed that the iridium fueled clads in the GPHS-RTG have high resistance to distortion induced by the impact of large, high velocity (>200 m/s), SRM casing fragments. It was concluded that the impact of large SRM fragments will cause little clad disruption at early Mission Elapsed Time (MET), and that the effects of these impacts will be less severe than had initially been believe. There are three copies in the file.
Date: January 1, 1989
Creator: Eck, Marshall B. & Mukunda, Meera
Partner: UNT Libraries Government Documents Department

On the Response of the GPHS Fueled Clad to Various Impact Environments

Description: The General Purpose Heat Source (GPHS) was developed by Department of Energy personnel and their contractors to provide a safe and mass efficient method of packaging the radioactive isotope 238Pu02 for use in space power systems. The characteristics of this heat source and its development history are well documented in numerous reports and papers and will not be revisited here. There is a duplicate copy. There is also a copy in the Energy Systems files.
Date: July 1, 1988
Creator: Eck, Marshall B & Mukunda, Meera
Partner: UNT Libraries Government Documents Department

Predicting the Velocity and Azimuth of Fragments Generated by the Range Destruction or Random Failure of Rocket Casings and Tankage

Description: The details of a predictive analytical modeling process as well as the development of normalized relations for momentum partition as a function of SRM burn time and initial geometry are discussed in this paper. Methods for applying similar modeling techniques to liquid-tankage-over-pressure failures are also discussed. These methods have been calibrated against observed SRM ascent failures and on-orbit tankage failures. Casing-quadrant sized fragments with velocities exceeding 100 m/s resulted from Titan 34D-SRM range destruct actions at 10 sec mission elapsed time (MET). Casing-quadrant sized fragments with velocities of approximately 200 m/s resulted from STS-SRM range destruct actions at 110 sec MET. Similar sized fragments for Ariane third stage and Delta second stage tankage were predicted to have maximum velocities of 260 m/s and 480 m/s respectively. Good agreement was found between the predictions and observations for five specific events and it was concluded that the methods developed have good potential for use in predicting the fragmentation process of a number of generically similar casing and tankage systems. There are three copies in the file, one of these is loose.
Date: October 1, 1988
Creator: Eck, Marshall B. & Mukunda, Meera
Partner: UNT Libraries Government Documents Department