Presentation to the Atomic Energy Commission and the Air Force, June 14, 1962

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This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

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Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

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This document i s a proposal prepared by the General Electric Company. The material is to be used only for evaluation to determine whether an award should be made, subject to the negotiation of a contract. The General Electric Company, therefore: A. Makes no warranty or representation, express or implied, with respect to any application, except for evaluation, of the information contained in this proposal, or that the use of any information, apparatus, material, method, or process disclosed in this proposal may not infringe privately owned rights; and B. Assumes no liabilities with respect to the use of, or for damages resulting from the use of any information, apparatus, material, method, or process disclosed in this

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Mo Ro Hayes - Div.. of Reactor Development, AEC Eo E. Jukkola - ASD, Materials Central, USAF Do Ho Lennox - Argonne National Laboratory Jo Fo Marchaterre - Argonne National Laboratory Ro A. Noland - Argonne National Laboratory R. Go Oehl •= Div. of Reactor Development, AEC Eo Ao Aitken Ho Co Brass field R. Wo Brisk en Vo Po Calkins Co Lo Chase Eo Bo Delson Wo Ho Long Go Wo Pomeroy (2)

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TABLE OF CONTENTS 2. Current Technical Program ................................9 4. 2 Phase I Effort to be Accomplished in Fiscal Year 1963 . . . . 60 4. 3 Test Reactor Design and Development......o............. 73 4. 4 Reactor Test Program ....,,..o...oo.....o............. 74

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This volume contains the charts and backup material presented to the Atomic Energy Commission and Air Force on June 14, 1962, General Electric's Nuclear Materials and Propulsion Operation (formerly the Aircraft Nuclear Propulsion Department), during its work on the development of a nuclear power plant for manned aircraft, has made highly significant contributions and has developed outstanding capabilities in the following areas: These technological capabilities are uniquely applicable to the development of compact, high-performance nuclear power plants.

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The R-1 reactor was designed for the P - l power plant (first power plant studied for nuclear flight). This was to be a water-moderated reactor utilizing metallic fuel elements. The shield for this reactor was primarily water, supplemented by a lead and steel gamma shield at the forward end. When the P-1 program was discontinued, the reactor and propulsion components were under final design and development; fuel element development was proceeding satisfactorily; exploratory critical experiments had been p e r - formed; and a full-scale shield mockup had been constructed. In the absence of a specific power plant objective (after the P-1 cancellation), it was decided that the most effective way to provide direction to component development would be to perform a series of nuclear experiments using reactor types with potential application to aircraft propulsion systems These experiments were designated Heat Transfer Reactor The first experiments! reactor, HTRE No. 1, was an air-cooled water-moderated reactor using nickel chromium concentric ring fuel elements containing uranium dioxide dispersed in nickel chrome. This reactor was first operated at full nuclear power in 1956, in the Core Test Facility (CTF) at the Idaho Test Station, The original test objective was 100 hours operation at full power; the actual operation time was 150 hours at full nuclear power. During operation, fuel element temperatures reached ISOO'^F and reactor discharge air temperatures were approximately 1400°F. During this experiment, the first known operation of a high-temperature, gas turbine engine from a nuclear heat source was The second experiment, HTRE No. 2, was conducted to test a variety of metallic and ceramic reactor componentSo For this experiment, the HTRE No. 1 reactor was modified to accommodate large test specimens.

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Thirteen different inserts were tested in the HTRE No. 2 reactor for a total of over 1300 hours. The majority of these insert tests were of ceramic fuel element assemblies in which fuel element temperatures reached 3000°F with an exit air temperature of 2200OF. HTRE No. 2 operation verified the use of hydrided zirconium as a metallic reactor material. During the ceramic insert tests, the integrity of clad materials to prevent water vapor corrosion was verified. Valuable data was collected on fission fragment release, deposition on ducting and other components, filtration, and atmospheric diffusion. The third experiment, HTRE No. 3, differed from the fiBst two r e a c - tors m three basic wayss (1) it had a solid moderator, (2) the reactor was horizontal, and (3) the aingle reactor supplied heat for two turbojet engines operating simultaneously. The use of lightweight hydrided z i r - conium as a moderator in place of water, reduced the complexity of the reactor. The HTRE NOo 3 experiment was conducted to provide the technical information needed for the design of a ground test prototype power plant and to evaluate and further develop materialSo The HTRE No. 3 reactor was successfully operated for 150 hours with fuel element temperatures of ISOO^F and exit air temperatures near Duimg GE-ANP operations, approximately 700 metallic fuel car= tridges were fabricated. These fuel cartridges were tested for a total of approximately 20. 000 hours. Approximately 1,000,000 ceramic fuel elements were fabricated. Elements of this tl^ were tested at temperatures to greater than 2400°F for a total of approximatelj 17,000 hours in-pile, and about 70,000 hours L 3 NMPO TECHNICAL PERSONNEL At the present time, there a r e approximately 480 people at Evendale. Of these 160 a r e technical personnel, including 18 PhD's. They have an average of 15 y e a r s experience each and an average of 7 to 8 years each on the project. Approximately 80 a r e in fundamental materials and 80 in systems, design, and application work. At the Idaho Test Station there a r e 33 technical personnel, of which 4 hold PhD's, out of a total employment of 127.

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2. CURRENT TECHNICAL PROGRAM This section describes the nature of the work under the High Temperature Materials Program sponsored by the Atomic Energy Commission. This program is divided into two sections, metallurgy and ceramics. For this presentation it will be regrouped into specific categories rather than discuss each of the 18 separate jobs. Progress reports pertaining to this program are issued monthly and annually in the GEMP s e r i e s . The objective of this job is to determine the effects of irradiation on BeO as a function of composition, density, and grain size of the composite body. The determination of the mechanism of growth and subsequent recovery on annealing are also being studied in the program. The most notable observation to date is the influence of preferred orientation on the radiation behavior. Certain compositions can be fabricated with a high degree of preferred orientation and exhibit less damage. Heat Resistant Alloys The objectives of this work are to study the nature and causes of the loss in life-time properties of the precipitation-hardened alloys, such as Inconel-X and A-286. A very marked reduction in the stress rupture life of these alloys has been observed in all of the precipitationhardened alloys studied so far. Solid solution alloys, such as Haslelloy-X, do not show a loss in the s t r e s s rupture life. The mechanism of damage is not completely understood; however, it seems to be concentrated in the grain boundary region. The damage, at least in part, is caused by thermal neutrons. METALLIC FUEL ELEMENTS FOR OXIDIZING ATMOSPHERES The objective of this work is to study the properties of various oxidation-resistant alloys for fuel element application. This includes the Fe-Cr-Al-Y family of alloys and their compatibility with UO2. The reaction between aluminum in the alloy and UO2 to produce uranium metal which migrates to the surface has been largely eliminated by small additions of chromium oxide to the UO2 to form a barrier and prevent reactiouo This Job also includes a study of the noble metals and their comThe objective of this work is to provide high temperature control rod materials for various nuclear applications. Earlier studies concentrated on extending the high temperature properties of EU2O3 by using alloys other than Nichrome. However, the reaction of the Eu^jO^ with

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yttrium in the Fe-Cr-Y alloy has prevented its use with the Fe-Cr s y s - tem in the higher temperature regions. More recent work has included a more detailed study of the Eu-O phase diagram and the compatibility of EuOx with refractory metals, such as tungsten, columbium, and The early portion of this work consisted of determining the effects of Irradiation on the shield materials that were developed under the GE-ANPD Program, beryllium plus boron and beryllium oxide plus boron carbide. More recent work has included characterization and evaluation of various hydrides containing small quantities of boron. Materials Properties for Direct Conversion The objective of this work is to determine properties of materials used in direct conversion devices, such as thermal emf, electrical conductivity, thermal conductivity, and thermal expansion. The main feature of this program is to measure tJiese properties in the higher temperature regions where we have unique capability, i o e , , 2000° to 3000°C. The objective of this work is to develop specialized components that provide greater reactor safety and environmental sensing capability at higher temperatures. Some of this work is applicable to nuclear rockets and nuclear space applications as well as civilian applications. Specific components which are being developed a r e : (1) electromagnetic drive mechanism for control rods; (2) static switching devices for reactor safely; (3) capacitance temperature sensing elements; and (4) high temperature nuclear sensors, such as an a-c ionization chamber which is readily adaptable to telemetering from space. CERAMIC FUEL ELEMENT TECHNOLOGY This work includes six items dealing with the development of ceramic fuel elements that are dispersions of stabilized fuels in a BeO matrix. It is an extension of work started in the GE-ANPD Program and now is applicable to the PLUTO Program and the long range programs in the civilian power field. The high thermal conductivity and the good moderating properties make BeO matrix Is being used by the PLUTO Program and in a number of gas-cooled reactors for civilian applications.

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The use of stabilized fuels as dispersions in BeO has been studied in GE-ANPD since 1955. The PLUTO Program has recently adopted this concept of fuel stabilization. Fuel stabilization enables one to add a UOo solid solution in air without appreciable volatilization of the UO2 as UO3 gas, and prevents a large volume change that occurs on oxidation of UOA to U30g which virtually destroys a BeO matrix containing a dispersion of UO2. The critical factor in stabilizing UO2 is to add significant quantities of Y2O3 in solution so that the net oxygen-to-metal ratio is less than 2, When the fluorite solid solution is less than 2, it becomes oxygen deficient which apparently improves the stability with regard to volatilization. The earliest stabilized fuels used only Y2O3 and UO2 in solid solution; however, these compositions lead to the formation of the eutectic with BeO at 2870°F and, therefore, are limited to temperatures below the eutectic. Late in the GE-ANPD Program it was found that adding small additions of zirconia to the urania-yttria solid solution produced even better fuel retention and no eutectic reaction was observed at 2870°F. Our present work is aimed at characterizing this latter composition in BeO for use at temperatures of 3000°F and higher. Coated Particles, Ceramic Coatings on Ceramics, Fission Product These three items are corollary programs to study the fission product transport in dispersed oxide systems and to develop suitable techniques of preventing fission product escape. One method being investigated to prevent fission product release is to coat the dispersed fuel particle itself, and another is by vapor deposition of the dense ceramic coatings on the fuel element surface. The latter Items is an outgrowth from the studies on the BeO fuel element where it was found that the specific compoundof the composition of U03* 3Y2O3 was extremely stable with respect to volatilization in air to temperatures as high as 2000°C. Furthermore, it was found that dense bodies of this material could be cycled between oxidizing and reducing atmospheres without loss of fuel or strength of the body. This property is unusual in high-temperature fuel element materials and offers unique application in the aerospace field where both atmospheres may be encountered. This composition would be used in fast reactor applications. Its properties and fabrication techniques are being studied in detail.

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GRAPHITE FUEL ELEMENT TECHNOLOGY This work is being performed in co-ordination with the Los Alamos Laboratory and includes the studies of fabrication techniques and hightemperature properties of graphitic systems. Principal studies to date have included the evaluation of urania-zlrconia-carbide dispersions in graphite and a detailed study of the curing and sintering process in which furfuryl alcohol has been used as a binder. The alcohol polymerizes and carbonizes without an unusually high release of permanent gases. Detailed studies are being carried out on the rheological properties of the furfuryl alcohol system on heating to high temperatures to achieve the optimum conditions for carbonization.

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The objective of advanced concept work during the last several years has been to find a reactor system that would be best qualified for various applications to propulsion and mobile power generating equipment. In addition to the usual requirements for high efficiency and low weight, these systems were to have long life, multiple r e s t a r t and part loading appears to offer the best potential for meeting the requirements of all systems studied and known to date. Moderated and unmoderated reactors utilizing materials having metallic and others having basically ceramic characteristics were

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Advantages of the fast-spectrum, refractory-metal reactor result from both the use of the fast-neutron spectrum and the use of metallic materials as listed in the chart. NMPO and its parent organization for several years. Three reports summarizing the essential results have been issued: GE-NMP 61-13 - "Proposal for the Study of the Application of Small Nuclear Rockets to Maneuverable Orbital Vehicles" Reactors for Propulsion and Power Generation" GE-NMP 62-14 - "Proposal for the Preliminary Systems Design of a Nuclear Rocket Engine for Application in Maneuverable A major effort was made to supply answers to all questions raised during …