K. K. S. Pillay is the Project Leader for Waste Management, NMT-DO.
The recommendations in this editorial are mine; they do not represent the opinion of Los Alamos National Laboratory, the University of California, the Department of Energy, or the U.S. Government.
The U.S. Department of Energy (DOE) has significantly downsized its nuclear weapons complex (facilities, infrastructure, and work force) over the past several years, and the process is continuing with the eventual goal of maintaining a small, environmentally benign, efficient operation. As part of this ideal goal, the DOE is embarked on a number of programs to dispose of nuclear materials presently considered excess to national security needs. Although several government agencies as well as private industries and universities have potential uses for these materials, disposition strategies for all excess nuclear materials are being evaluated solely by the DOE's nuclear material integration (NMI) program. Since DOE's current mission is to clean up the environmental legacies of the past, excess materials are considered a liability.
The purpose of this article is to voice my concern and to alert the scientific community of an opportunity to participate in a thoughtful process of planning to preserve some of the valuable materials within the DOE complex for the future. A number of these materials may be considered excess to national security, but they are extremely valuable resources for the future of nuclear science and technology. Unfortunately, some of these unique materials have already been dumped into high-level waste tanks in the name of "mortgage reduction," (reducing legacy waste) and are not replaceable in the near future. The U.S. weapons complex at one time had the only facilities and resources in the free world to produce some of the uncommon and uniquely valuable nuclear materials. Those facilities are being eliminated altogether in the name of "mortgage reduction." Since there is no chance that such facilities will be rebuilt in the foreseeable future, we should at least consider saving, (as "national treasures" for the future) some of the unique resources they produced.
A number of man-made elements and radioactive isotopes are unique and should be saved from being discarded as waste or declared excess to national security needs. Unfortunately, the definition of "national security needs" is too narrow to include future needs of science and technology. Therefore, the ongoing discussions about nuclear material disposition do not include a strategy to save some of these rare gems for future generations. Pleas made by many distinguished scientists, including Dr. Glenn Seaborg, as early as 1994, have yet to produce any tangible results. As a result, future generations will be learning about the golden days of nuclear technology in the U.S. as we are presently learning about the dinosaurs.
The origins of many of the presently known applied nuclear technologies world-wide can be traced to U.S. research. However, the past two decades have shown a serious deterioration of the role of our nuclear sciences as evidenced by the closing of academic programs and nuclear facilities in universities and elimination of national support for such programs. In the frenzy to reduce nuclear weapons and pursue the ideal goal of eliminating all weapons of mass destruction, we have involuntarily succumbed to the abandonment of all beneficial uses of nuclear technologies. Since we know that today's technology innovations are based on yesterday's research, it is hard to fathom where tomorrow's technologies are going to come from under these conditions. Somehow, we have lost the initiatives and leadership in this area as the rest of world is moving forward and reaping the benefits of past nuclear research to better their lives.
The uniqueness of some of the incidentally gathered material resources of the DOE complex can be illustrated using their potential value to nuclear medicine. According to the Institute of Medicine of the National Academy of Sciences, in the U.S., isotopes are used daily in more than 36,000 diagnostic imaging procedures and in close to 100 million laboratory tests annually.
These isotopes also play a major role in treatment. The continuing growth in radioimmunotherapy and the rapid developments in the new field of brachy-therapy for localized cancer treatment are areas that require special attention during the NMI process because most of the active ingredients used here are short-lived alpha-emitters. These, in turn, are derived from a variety of long-lived heavy isotopes of unique characteristics, not available outside the DOE complex.
Typical examples include 229Th, 227Ac, and 225Ac, which are intermediates separated and purified from various DOE source materials (namely 233U, 235U, and 232Th). These intermediates are used primarily for the production of their daughters, 231Bi, 223Ra, and 212Bi, which are the short-lived alpha emitters used in therapy. Although it is theoretically possible to use a high-flux reactor to produce 229Th and 227Ac from 226Ra, we are limited by the insufficient availability of high-flux neutron sources within the U.S. Even if we decided to use foreign facilities for irradiation, the starting materials 233U, 235U, 232Th, and 226Ra) would have to be preserved from the current inventories within the DOE complex.
At one time, the DOE complex was the sole source of transuranic elements used by universities and research to study the beneficial applications of such elements and to use them to increase our knowledge of the world around us. One unique example is that of the isotope 252Cf, a spontaneous fission source and efficient source of neutrons. In addition to its many beneficial uses in medicine, 252Cf has been used in industry for neutron radiography and activation analyses, and by the weapons complex for testing the safety of nuclear weapons. Since this is an isotope with a relatively short (2.65 years) half-life, it is important to preserve the parent nuclides such as 243Am, and 244Cm to produce this material in the future. Rare isotopes are also necessary in our search for the island of stability in the periodic table beyond presently known elements. Limited quantities of Am, Cm, Bk, and Cf now available within the DOE complex are likely to end up in high-level waste tanks if a deliberate effort is not made to salvage them.
As a practical matter we also need 238Pu as a reliable source of thermoelectric power for extended space missions and a variety of terrestrial applications. Presently, the supply of 238Pu in the U.S. is the lowest ever. At the same time, we are told that there is now a wish list of 40 NASA missions requiring 238Pu radioactive thermoelectric generators for power. This problem can be solved by creatively using two other isotopes available within the DOE complex-237Np and 241Am-that are considered excess to national security. Both these isotopes can be readily converted into 238Pu via neutron irradiation. Such an approach would address the problems of these three isotopes at the same time.
So-called "excess materials" now within the DOE complex are invaluable resources that should be preserved for the future of medicine, research, and space exploration. The investments required to stabilize and store these valuable resources are minuscule compared to investments already made by U.S. taxpayers to create them. The DOE NMI progam must recognize that proper management of these resources is absolutely essential to the future of science and technology and to the future of the nation.
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