Reduction Agency (DTRA), requested that the National Research Council examine and assess the TOPAZ International Program that the DNA was then conducting. The DNA asked for an assessment of the following:

  • The status of the program at the time;

  • The value of continuing the ongoing activities as they related to developing operational space nuclear power systems;

  • The possible effects of discontinuing certain elements of the program;

  • The state of the TOPAZ reactor technology in relation to the equivalent U.S. technology;

  • The value of establishing revised goals for the program; and

  • Steps DNA could take to serve the national interest more effectively, including continuing, modifying, expanding, or discontinuing the program.

Representatives of various organizations in DoD, DOE, and NASA, together with Russian interests, U.S. industrial companies, and private individuals, participated in the 1996 deliberations on the TOPAZ International Program. Since the TOPAZ International Program was devoted to thermionic system advancement, the 1996 report’s assessment is relevant in many respects to the current examination requested by DTRA. Although no work has been conducted in the United States related to the TOPAZ International Program since the program was discontinued in 1996 and the TOPAZ hardware was returned to Russia, many of the factors considered by the previous committee and the conclusions it reached are still valid. The conclusions of the 1996 report, and the current committee’s observations, are summarized below.

  • Support of high power, long lifetime nuclear systems. The 1996 TOPAZ committee stated that one objective of a U.S. thermionics program should be to advance critical technologies that could support potential future high power, long lifetime space nuclear reactor systems. However, at that time the program did not have sufficient funds to advance the critical technologies required for such a nuclear system. Those funds are still not available.

  • User applications. The 1996 TOPAZ committee emphasized throughout its report that there were no dedicated users or then-current applications for thermionic or nuclear technology. The 1996 committee also found that there were no planned or confirmed mission-directed activities within the TOPAZ International Program. While the Solar Orbital Transfer Vehicle program may address this issue with respect to solar thermionic systems, there is still no confirmed mission for a nuclear thermionic system.

  • Knowledge capture. The 1996 TOPAZ committee found that the TOPAZ International Program had no formal mechanisms to record and archive the technical knowledge gained from the space power nuclear reactor technology efforts so that it would be accessible for future efforts. There is still no formal archival method being used today in the DTRA thermionics program.

  • Collaboration. The TOPAZ committee found that an integrated and collaborative interagency approach that existed in earlier nuclear power development programs, such as SP-100, had broken down.

  • Role of government. The 1996 TOPAZ committee found that there is a role for the government in research and development for thermionics because U.S. companies often do not have sufficient economic motivation to maintain the scientific and engineering staffs or facilities to support continued work on high risk, long-term projects such as thermionics. The situation has not changed since 1996.

All of the points made by the TOPAZ committee in 1996 are relevant to the current situation in the DTRA thermionics program. In contrast to the previous committee, the current committee, as already stated, recommends that emphasis be placed on solar thermionics research as a near-term goal and that nuclear thermionics research, as advocated by the 1996 NRC committee, be viewed as a long-term goal.

The current funding situation is analogous to the funding that existed for the TOPAZ International Program in 1995 and 1996: that is, year-to-year funding mandated by Congress limits the efforts. The conclusions listed above should help guide future thermionics work aimed at space nuclear power.

The 1996 TOPAZ committee considered six program options that ranged from terminating the TOPAZ program to revisiting the possibility of conducting a flight test and revamping the overall program. The TOPAZ International Program was canceled shortly after the committee’s report was released, and no further work has been conducted.

The following is a paraphrased account of some of the recommendations from the 1996 report that would be relevant to a future nuclear thermionics program in the United States:

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