Radioactive Waste Disposal And Geology

The perception of radioactive waste as a major problem for the industrial world has developed only recently. Four decades ago the disposal of such waste was regarded as a relatively minor matter. Those were the heady days when nuclear fission seemed the answer to the world's energy needs: the two wartime bombs had demonstrated its awesome power, and now it was to be harnessed for the production of electricity, the excavation of canals, even the running of cars and airplanes. In all applications of fission some waste containing radioactive elements would be generated of course, but it seemed only a trivial annoyance, a problem whose solution could be deferred until the more exciting challenges of constructing reactors and devising more efficient weapons had been mastered. So waste accumulated, some in tanks and some buried in shallow trenches. These were recognized as only temporary, makeshift measures, because it was known that the debris would be hazardous to its surroundings for many thousands of years and hence that more permanent disposal would someday be needed. The difficulty of accomplishing this more lasting disposal only gradually became apparent. The difficulty has been compounded by uncertainty about the physiological effects oflow-Ievel radiation, by the inadequacy of detailed knowledge about the behavior of engineered and geologic materials over long periods under unusual conditions, and by the sensitization of popular fears about radiation in all its forms following widely publicized reactor accidents and leaks from waste storage sites.

The perception of radioactive waste as a major problem for the industrial world has developed only recently. Four decades ago the disposal of such waste was regarded as a relatively minor matter. Those were the heady days when nuclear fission seemed the answer to the world's energy needs: the two wartime bombs had demonstrated its awesome power, and now it was to be harnessed for the production of electricity, the excavation of canals, even the running of cars and airplanes. In all applications of fission some waste containing radioactive elements would be generated of course, but it seemed only a trivial annoyance, a problem whose solution could be deferred until the more exciting challenges of constructing reactors and devising more efficient weapons had been mastered. So waste accumulated, some in tanks and some buried in shallow trenches. These were recognized as only temporary, makeshift measures, because it was known that the debris would be hazardous to its surroundings for many thousands of years and hence that more permanent disposal would someday be needed. The difficulty of accomplishing this more lasting disposal only gradually became apparent. The difficulty has been compounded by uncertainty about the physiological effects oflow-Ievel radiation, by the inadequacy of detailed knowledge about the behavior of engineered and geologic materials over long periods under unusual conditions, and by the sensitization of popular fears about radiation in all its forms following widely publicized reactor accidents and leaks from waste storage sites.

Focused attention by world leaders is needed to address the substantial challenges posed by disposal of spent nuclear fuel from reactors and high-level radioactive waste from processing such fuel. The biggest challenges in achieving safe and secure storage and permanent waste disposal are societal, although technical challenges remain. Disposition of radioactive wastes in a deep geological repository is a sound approach as long as it progresses through a stepwise decision-making process that takes advantage of technical advances, public participation, and international cooperation. Written for concerned citizens as well as policymakers, this book was sponsored by the U.S. Department of Energy, U.S. Nuclear Regulatory Commission, and waste management organizations in eight other countries.

The perception of radioactive waste as a major problem for the industrial world has developed only recently. Four decades ago the disposal of such waste was regarded as a relatively minor matter. Those were the heady days when nuclear fission seemed the answer to the world's energy needs: the two wartime bombs had demonstrated its awesome power, and now it was to be harnessed for the production of electricity, the excavation of canals, even the running of cars and airplanes. In all applications of fission some waste containing radioactive elements would be generated of course, but it seemed only a trivial annoyance, a problem whose solution could be deferred until the more exciting challenges of constructing reactors and devising more efficient weapons had been mastered. So waste accumulated, some in tanks and some buried in shallow trenches. These were recognized as only temporary, makeshift measures, because it was known that the debris would be hazardous to its surroundings for many thousands of years and hence that more permanent disposal would someday be needed. The difficulty of accomplishing this more lasting disposal only gradually became apparent. The difficulty has been compounded by uncertainty about the physiological effects oflow-Ievel radiation, by the inadequacy of detailed knowledge about the behavior of engineered and geologic materials over long periods under unusual conditions, and by the sensitization of popular fears about radiation in all its forms following widely publicized reactor accidents and leaks from waste storage sites.

During the next several years, decisions are expected to be made in several countries on the further development and implementation of the geological disposition option. The Board on Radioactive Waste Management (BRWM) of the U.S. National Academies believes that informed and reasoned discussion of relevant scientific, engineering and social issues can-and should-play a constructive role in the decision process by providing information to decision makers on relevant technical and policy issues. A BRWM-initiated project including a workshop at Irvine, California on November 4-5, 1999, and subsequent National Academies' report to be published in spring, 2000, are intended to provide such information to national policy makers both in the U.S. and abroad. To inform national policies, it is essential that experts from the physical, geological, and engineering sciences, and experts from the policy and social science communities work together. Some national programs have involved social science and policy experts from the beginning, while other programs have only recently recognized the importance of this collaboration. An important goal of the November workshop is to facilitate dialogue between these communities, as well as to encourage the sharing of experiences from many national programs. The workshop steering committee has prepared this discussion for participants at the workshop. It should elicit critical comments and help identify topics requiring in-depth discussion at the workshop. It is not intended as a statement of findings, conclusions, or recommendations. It is rather intended as a vehicle for stimulating dialogue among the workshop participants. Out of that dialogue will emerge the findings, conclusions, and recommendations of the National Academies' report.

Many countries are currently exploring the option to dispose of highly radioactive solid wastes deep underground in purpose built, engineered repositories. A number of surface and shallow repositories for less radioactive wastes are already in operation. One of the challenges facing the nuclear industry is to demonstrate confidently that a repository will contain wastes for so long that any releases that might take place in the future will pose no significant health or environmental risk. One method for building confidence in the long-term future safety of a repository is to look at the physical and chemical processes which operate in natural and archaeological systems, and to draw appropriate parallels with the repository. For example, to understand why some uranium orebodies have remained isolated underground for billions of years. Such studies are called 'natural analogues'. This book investigates the concept of geological disposal and examines the wide range of natural analogues which have been studied. Lessons learnt from studies of archaeological and natural systems can be used to improve our capabilities for assessing the future safety of a radioactive waste repository.

There is an extremely voluminous literature on radioactive waste and its disposal, much in the form of government-sponsored research reports. To wade through this mountain of literature is indeed a tedious task, and it is safe to speculate that very few, if any, individuals have the time to examine each report that has been issued during the preceding ten years. This book attempts to summarize much of this literature. Further, many workers in the geosciences have not received training in the nuclear sciences, and many nuclear scientists could be better versed in geology. In this book an attempt is made to cover some background material on radioactive wastes and geotoxicity that may not be an integral part of a geologist's training, and background material on geology and geochemistry for the nuclear scientist. The geochemical material is designed for both the geoscientist and the nuclear scientist. There is no specific level for this book. Certainly, it should be useful to advanced undergraduates and graduates studying geology and nuclear science. It does not pretend to cover a tremendous amount of detail in all subjects, yet the references cited provide the necessary source materials for follow-up study. It is my intention that the reader of this book will have a better, broader understanding of the geochemical aspects of radioactive waste disposal than is otherwise available in anyone source.