2
Conclusions Regarding the Current DTRA Program

THE MISSION OF THE DEFENSE THREAT REDUCTION AGENCY

Thermionics, as a technical entity, is in danger of disappearing. The infrastructure and technology base will disappear unless continued support is provided. Both applied research and basic research are required to maintain the technical infrastructure and attract competent researchers.

The biggest challenge to maintaining a strong thermionics technology program is finding an interested user. The only potential users for thermionics-based technology that the committee has identified are described in Chapter 3. In addition, there seems to be little interest in or enthusiasm for thermionics within the Defense Threat Reduction Agency (DTRA) itself. This is understandable, because the goals of a thermionics research and development program do not coincide with the stated mission of the DTRA.

The Defense Threat Reduction Agency safeguards the United States and its friends from weapons of mass destruction (chemical, biological, radiological, nuclear and high explosives) by reducing the present threat and preparing for the future threat. DTRA’s work covers a broad spectrum of activities—shaping the international environment to prevent the spread of weapons of mass destruction [WMD], responding to requirements to deter the use and reduce the impact of such weapons, and preparing for the future as WMD threats emerge and evolve.1

Thermionics technology and devices have traditionally been closely tied to nuclear power applications. As a result, early on there was an indirect link between thermionics and the DTRA mission statement in that research in thermionics was able to employ Russian nuclear specialists. However, in recent years, thermionics technology has been increasingly applied to other, non-nuclear applications. As a result, the goals of the thermionics research and technology effort are no longer compatible with the DTRA mission statement.

Finding: The thermionics research and development effort does not fit within DTRA’s current mission.

In discussions with the committee, representatives from the Air Force Research Laboratory (AFRL) indicated an interest in expanding their role in thermionic research and development. In fact, they are currently working in thermionics with the solar orbital transfer vehicle (SOTV) and the high-power, advanced, low-mass (HPALM) concepts as discussed in Chapter 4. This interest in thermionics is logical since the AFRL has the mandate to develop future power supplies for the Air Force, and thermionics could potentially play a role.

The committee believes that it is prudent for the AFRL to assume all responsibilities for thermionic research and development on behalf of the federal government for the following reasons:

  • The AFRL has the mandate to work with power conversion technologies, one of which is thermionics.

  • The responsible parties at AFRL have expressed an interest in developing thermionic technology.

  • The AFRL is already supporting thermionic efforts at a low level.

Recommendation 1. The United States Congress and the Administration should transfer responsibil-

1  

The DTRA mission statement is available online at <http://www.dtra.mil>.



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Thermionics Quo Vadis?: An Assessment of the DTRA’s Advanced Thermionics Research and Development Program 2 Conclusions Regarding the Current DTRA Program THE MISSION OF THE DEFENSE THREAT REDUCTION AGENCY Thermionics, as a technical entity, is in danger of disappearing. The infrastructure and technology base will disappear unless continued support is provided. Both applied research and basic research are required to maintain the technical infrastructure and attract competent researchers. The biggest challenge to maintaining a strong thermionics technology program is finding an interested user. The only potential users for thermionics-based technology that the committee has identified are described in Chapter 3. In addition, there seems to be little interest in or enthusiasm for thermionics within the Defense Threat Reduction Agency (DTRA) itself. This is understandable, because the goals of a thermionics research and development program do not coincide with the stated mission of the DTRA. The Defense Threat Reduction Agency safeguards the United States and its friends from weapons of mass destruction (chemical, biological, radiological, nuclear and high explosives) by reducing the present threat and preparing for the future threat. DTRA’s work covers a broad spectrum of activities—shaping the international environment to prevent the spread of weapons of mass destruction [WMD], responding to requirements to deter the use and reduce the impact of such weapons, and preparing for the future as WMD threats emerge and evolve.1 Thermionics technology and devices have traditionally been closely tied to nuclear power applications. As a result, early on there was an indirect link between thermionics and the DTRA mission statement in that research in thermionics was able to employ Russian nuclear specialists. However, in recent years, thermionics technology has been increasingly applied to other, non-nuclear applications. As a result, the goals of the thermionics research and technology effort are no longer compatible with the DTRA mission statement. Finding: The thermionics research and development effort does not fit within DTRA’s current mission. In discussions with the committee, representatives from the Air Force Research Laboratory (AFRL) indicated an interest in expanding their role in thermionic research and development. In fact, they are currently working in thermionics with the solar orbital transfer vehicle (SOTV) and the high-power, advanced, low-mass (HPALM) concepts as discussed in Chapter 4. This interest in thermionics is logical since the AFRL has the mandate to develop future power supplies for the Air Force, and thermionics could potentially play a role. The committee believes that it is prudent for the AFRL to assume all responsibilities for thermionic research and development on behalf of the federal government for the following reasons: The AFRL has the mandate to work with power conversion technologies, one of which is thermionics. The responsible parties at AFRL have expressed an interest in developing thermionic technology. The AFRL is already supporting thermionic efforts at a low level. Recommendation 1. The United States Congress and the Administration should transfer responsibil- 1   The DTRA mission statement is available online at <http://www.dtra.mil>.

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Thermionics Quo Vadis?: An Assessment of the DTRA’s Advanced Thermionics Research and Development Program ity for the technical management of the Defense Threat Reduction Agency’s thermionics program to the Air Force Research Laboratory. Doing so would enhance the technical continuity for the technology and place the program in an agency responsible for developing power systems and conversion technologies. As the focal point for thermionic research, the Air Force Research Laboratory should attempt to establish cooperative activities with other government agencies, such as the Department of Energy, the Naval Research Laboratory, NASA, and the Air Force Office of Scientific Research. By transferring thermionics research and development to the AFRL, the federal government would establish one thermionics focal point, for the AFRL could then become the thermionics community coordinator and employ the existing Space Technology Alliance (STA) and the Interagency Advanced Power Group (IAPG) to coordinate efforts and disseminate information. The STA is a U.S. government forum for increasing collaboration across government, industry, and academia. The alliance comprises eight government organizations: the departments of the Air Force, Army, and Navy; the Ballistic Missile Defense Organization; the Defense Advanced Research Projects Agency; the Department of Energy (DOE); the National Aeronautics and Space Administration (NASA); and the National Reconnaissance Office. IAPG is a U.S. government forum whose goal is to increase collaboration in power technology research and development activities across the government. The IAPG operates the Power Information Center, which distributes summaries of current and past projects in power technology to member organizations. To achieve this aim, the AFRL, or other sponsoring agency, could establish interagency collaborations on thermionics with NASA, the DOE, the Naval Research Laboratory, and the Air Force Office of Scientific Research.2 WORK CONDUCTED UNDER THE DTRA PROGRAM In general, the committee found that most of the research and development sponsored by the DTRA has been good. The benefits in the materials regime are especially apparent as discussed in Chapter 7. The DTRA has accomplished what appears to be solid results in the single-crystal research area, largely by sponsoring research conducted by Russian research institutes. Finding: DTRA-sponsored efforts in thermionics have yielded respectable technical results at a relatively modest funding level. However, in general the DTRA thermionics research and development program is attempting to accomplish too many things given the modest levels of funding that are available. The committee appreciates the efforts of the DTRA management team to date and understands that DTRA is attempting to create a technology base of useful elements that other programs or initiatives might use in the future (see Table 2.1). The committee believes, however, that other system programs or mission initiatives will not consider using thermionic power system technology since the technology is largely undemonstrated at the level of a complete power system. Also, future needs for any power conversion technology will be driven by the potential requirements of future mission systems. Since the farterm continuation of a thermionics program is contingent upon the technology actually being used, the committee strongly believes that future thermionics research and development should be localized around a potential sponsor effort. The committee has kept this philosophy in mind when constructing the recommendations in this report. Finding: The present DTRA program is spread among too many different areas to allow a large impact in any one area. The DTRA thermionics technology program has been affected by the method of funding and by the manner in which the program has been administered. Since the program has been funded by so-called congressional plus-up funds, there is no long-range funding plan. As a result, no long-range plan for technology has been put in place and pursued that would result in the technology being available on a system level in the foreseeable future. The committee found that there is a general lack of continuity and coordination of funding for the current thermionics research program. The current program tends to focus on component technology and performance enhancement as the easi- 2   The term “sponsoring agency” is used to reflect the recommendation that the program be transferred from the DTRA to the AFRL.

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Thermionics Quo Vadis?: An Assessment of the DTRA’s Advanced Thermionics Research and Development Program TABLE 2.1 Major Elements of the DTRA Thermionics Program Major Thermionic Program Element Subelement Subtask Responsible Research Group Nuclear power in-core Conductively coupled/multi-cell thermionic fuel element (TFE) Trilayer insulation design, development, and device testing General Atomics in collaboration with Russian research facilities   Oxygenated thermionic converters Oxygenated electrode testing General Atomics in collaboration with Russian research facilities   Oxygen mass transport Russian research facilities High-creep strength fuel clad development Single-crystal alloy domestic fabrication and creep testing; closed chemical vapor deposition process Auburn University in collaboration with Russian research facilities Advanced thermionic converter: close-spaced converter Device development and testing Russian research facilities Advanced thermionic converter: low emissivity converter development Design and proof of concept Russian research facilities Microminiature thermionic converter (MTC) Proof of performance and theory validation Low work function coating development device testing Sandia National Laboratories with New Mexico Engineering Research Institute test support Thermionic theory and model validation Thermionic space reactor system mass model RSMASS-T system model upgrade DTRA staff   Thermionic theory and theory validation Vacuum converter theory development and surface effects modeling DTRA staff and consultants est way to structure a program with limited resources and little assurance of continued funding. However, a system oriented approach would be useful in identifying the major technology needs and tradeoffs early on. For example, the operating temperature regime of solar thermionic converters may be determined by factors such as the characteristics of the solar concentrator rather than by the limitations of the converter per se. Similarly, additional lifetime issues may be determined by factors such as thermal stresses caused by sunlight or eclipse transitions in orbit. The system oriented approach is particularly important for the case of advanced solar concentrator thermionic systems, which may present challenges that are significantly different from those presented by their nuclear counterparts. Combining this system oriented approach with improved record retention and knowledge capture, which are discussed below, will mean that other nonthermionics related work could take advantage of the advances made to date even if program funding were eliminated in the future. Recommendation 2. The sponsoring agency should generate a long-term plan to focus activities related to both solar and nuclear applications for thermionic technology.

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Thermionics Quo Vadis?: An Assessment of the DTRA’s Advanced Thermionics Research and Development Program KNOWLEDGE CAPTURE The committee found that the DTRA thermionics program has no formal mechanisms to ensure that the results of current work will be available to future researchers, including non thermionics researchers who may have interest in specific aspects of the DTRA research program. From experience, the committee knows that even with fairly large program efforts, research results can be lost due to inadequate record keeping and high personnel turnover. The amount of knowledge capture, or the lack thereof, appears to be independent of how complete any one research and development project may be but depends, rather, on the amount of knowledge captured during the process. One way to avoid the loss of hard-earned research results is through publication in peer reviewed journals. The thermionics program can benefit greatly from peer reviewed publications. To establish a true sense of a thermionics community, the sponsoring agency should encourage researchers and commercial developers in thermionics to broaden their sphere of interaction. Technology programs in general are strengthened by peer interaction and especially constructive peer criticism. To date, the researchers working under the DTRA thermionics program have not, with few exceptions, actively engaged in peer review. For example, the committee found it difficult to gather data on the string thermionic assembly research testbed (START) tests, and much of the data was not recorded, only alluded to. Finding: By having papers published under the thermionics research and development program peer reviewed, and by establishing a formal documentation and hardware storage protocol, the future sponsor will help prevent loss of hard-earned research and development knowledge. FUTURE THERMIONIC WORK WITH RUSSIA Collaboration between the U.S. and the former Soviet Union has significantly enhanced the U.S. technology base in the area of high temperature materials and thermionic conversion. Much of this collaboration involves Auburn University and General Atomics in the area of materials research. In addition to materials and thermionic conversion, dialogue in the area of nuclear safety has also developed. This dialogue, though not necessarily pertinent to the performance of thermionic converters, is certainly important and beneficial for the international spacefaring community (Booz-Allen and Hamilton 1993). Similarly, Russian technologists have expressed the desire to collaborate on ways that nuclear technology, and in particular thermionic nuclear technology, can enhance an international human mission to the Moon or even Mars, should such a mission take place (Ponomarev-Stepnoi et al. 1992). American specialists visited nuclear test facilities in Russia and discussed the possibility of collaboration. The conclusion of a report generated from that trip was that there could be beneficial collaborations with the Russians in certain technology areas (DOE 1992). The ability to perform high quality nuclear testing in fast neutron flux is considered to be vital to the development of nuclear thermionic systems or other types of space nuclear power and propulsion systems. Russia may still be able to provide such testing capability today. However, expanded collaboration between the United States and Russia has not occurred since the Space Exploration Initiative was canceled in 1993, and that effort was focused on the human exploration of the Moon and Mars. Despite the potential for positive results from continuing or expanded thermionic research and development collaboration with Russia, the committee has some concerns about the possibility of technology transfer to China. In-core thermionic fuel element testing was carried out by the Institute of Atomic Energy in Beijing in the 1980s (Shengquan 1984). In 2000, a TASS announcement from Moscow indicated that Russia and China had discussed collaborative efforts on nuclear reactors for Chinese satellites (FBIS 2000). Finding: Past involvement with the Russians in thermionic research has been beneficial, particularly in the area of materials research for thermionic electrodes and insulators. Future work with Russia should include testing the effects of radiation on material due to the lack of nuclear radiation test capability in the United States. Finding: The collaboration between General Atomics, Auburn University, and research facilities in Russia has been successful in advancing the U.S. thermionics research program. The involvement of Russia may also be beneficial in the future because of its capabilities for testing thermionics device-related technology in its fast neutron irradiation reactor test facilities.

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Thermionics Quo Vadis?: An Assessment of the DTRA’s Advanced Thermionics Research and Development Program REFERENCES Booz-Allen and Hamilton, Inc. 1993. Topaz International Program—Lessons Learned in Technology Cooperation with Russia. Contract SD1084–93-C-0010. DOE (Department of Energy). 1992. Report of the United States Space Nuclear Power and Propulsion Team: An Examination of the Space Nuclear Power and Propulsion Activities of the Commonwealth of Independent States. DOE, Washington, D.C., October 6. FBIS (Foreign Broadcast International Service). 2000. FBIS-CHI-2000– 0530. May 30. Ponomarev-Stepnoi, N.N., Pavshoock, Vladimir A., and Usov, Veniamin A. 1992. “NPS Options for Lunar Bases Power Supply,” American Institute of Physics Conference Proceedings 246(1):440–445. Shengquan, Cao. 1984. “Thermionic Converter for Space Reactor Description,” Chinese Journal of Nuclear Science and Engineering 4(3):227– 232.