Publications

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The launch of nuclear materials requires special care to minimize the risk of adverse effects to human health and the environment. This paper describes the special sources of risk that are inherent to the launch of radioactive materials and provides insights into the analysis and control of these risks that have been gained through the experience of previous US launches. Historically, launch safety has been achieved by eliminating, to the greatest degree possible, the potential for energetic insults to affect the radioactive material. For those insults that cannot be precluded, designers minimize the likelihood, magnitude and duration of their interaction with the material. Finally, when a radioactive release cannot be precluded, designers limit the magnitude and spatial extent of its dispersal.

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A simplified and bounding methodology for analyzing the pressure buildup and hydrogen concentration within an unvented 2R container was developed (the 2R is a sealed container within a 6M package). The specific case studied was the gas buildup due to alpha radiolysis of water moisture sorbed on small quantities (less than 20 Ci per package) of plutonium oxide. Analytical solutions for gas pressure buildup and hydrogen concentration within the unvented 2R container were developed. Key results indicated that internal pressure buildup would not be significant for a wide range of conditions. Hydrogen concentrations should also be minimal but are difficult to quantify due to a large variation/uncertainty in model parameters. Additional assurance of non-flammability can be obtained by the use of an inert backfill gas in the 2R container.

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In principle, the energy released by a fission can be converted directly into electricity by using the charged fission fragments. The first theoretical treatment of direct energy conversion (DEC) appeared in the literature in 1957. Experiments were conducted over the next ten years, which identified a number of problem areas. Research declined by the late 1960's due to technical challenges that limited performance. Under the Nuclear Energy Research Initiative the authors are determining if these technical challenges can be overcome with todays technology. The authors present the basic principles of DEC reactors, review previous research, discuss problem areas in detail, and identify technological developments of the last 30 years that can overcome these obstacles. As an example, the fission electric cell must be insulated to avoid electrons crossing the cell. This insulation could be provided by a magnetic field as attempted in the early experiments. However, from work on magnetically insulated ion diodes they know how to significantly improve the field geometry. Finally, a prognosis for future development of DEC reactors will be presented .

The Nuclear Material Focus Area (NMFA) is responsible for providing comprehensive needs identification, integration of technology research and development activities, and technology deployment for stabilization, packaging, and interim storage of surplus nuclear materials within the DOE complex. The NMFA was chartered in April 1999 by the Office of Science and Technology (OST), an organizational component of the US Department of Energy's (DOE) Office of Environmental Management (EM). OST manages a national program to conduct basic and applied research, and technology development, demonstration, and deployment assistance that is essential to completing a timely and cost-effective cleanup of the DOE nuclear weapons complex. DOE/EM provides environmental research results, as well as cleanup technologies and systems, to meet high-priority end-user needs, reduce EM's major cost centers and technological risks, and accelerate technology deployments. The NMFA represents the segment of EM that focuses on technological solutions for re-using, transforming, and disposing excess nuclear materials and is jointly managed by the DOE Albuquerque Operations Office and the DOE Idaho Operations Office.

Reactor power supplies offer many attractive characteristics for lunar surface applications. The Topaz II reactor resulted from an extensive development program in the former Soviet Union. Flight quality reactor units remain from this program and are currently under evaluation in the United States. This paper examines the potential for applying the Topaz II, originally developed to provide spacecraft power, as a lunar surface power supply.

Bimodal space reactor systems provide both thermal propulsion for the spacecraft orbital transfer and electrical power to the spacecraft bus once it is on station. These systems have the potential to increase both the available payload in high energy orbits and the available power to that payload. These increased mass and power capabilities can be used to either reduce mission cost by permitting the use of smaller launch vehicles or to provide increased mission performance from the current launch vehicle. A major barrier to the deployment of these bimodal systems has been the cost associated with their development. This paper describes a bimodal spacecraft bus with performance potential to permit more than 70% of the instrumented payload of the Titan IV/Centaur to be launched from the Atlas IIAS. The development cost is minimized by basing the design on existing component technologies.

Bimodal space reactor systems provide both thermal propulsion for the spacecraft orbital transfer and electrical power to the spacecraft bus once it is on station. These systems have the potential to increase both the available payload in high energy orbits and the available power to that payload. These increased mass and power capabilities can be used to either reduce mission cost by permitting the use of smaller launch vehicles or to provide increased mission performance from the current launch vehicle. A major barrier to the deployment of these bimodal systems has been the cost associated with their development. This paper describes a bimodal reactor system with performance potential to permit more than 70% of the instrumented payload of the Titan IV/Centaur to be launched from the Atlas IIAS. The development cost is minimized by basing the design on existing component technologies.

This paper presents an overview of the Nuclear Electric Propulsion Space Test Program (NEPSTP). The program goals, the proposed mission, the spacecraft, and the Topaz II space nuclear power system are described. The subject of flight qualification is examined and the inherent difficulties of qualifying a space reactor are described. The differences between US and Russian flight qualification procedures are explored. A plan is then described that was developed to determine an appropriate flight qualification program for the Topaz II reactor to support a possible NEPSTP launch. Refocusing of the activities of the Ballistic Missile Defense Organization (BMDO), combined with budgetary pressures, forced the cancellation of the NEPSTP at the end of the 1993 fiscal year.