With growing concern about the stability of the climate, there are compelling reasons to support an expansion of nuclear capacity. Historically, public support for nuclear power has been tentative, and recent events in Fukushima have not helped the image of nuclear as a fuel option for the future. The threat of industrial accidents and terrorism are not the only concerns that paint nuclear energy with a palette of dark and imposing hues. The inevitable by-product of nuclear processes is the production of radioactive waste. Nuclear fuel sources continue to pose a risk to human and ecosystem health, long after energy is extracted or weapons are developed. Experts hope that disposal deep underground will eventually mitigate these risks. Development of geologic disposal is challenged by many factors, including the threat of tectonic activity, gas buildup, rock permeability, and uncertain performance of engineered systems over many thousands of years.
A recent study was prepared with backing from the National Ground Water Association and published in Environmental Science and Technology. The authors explore questions regarding methods of storage and disposal of radioactive materials with respect to short, medium, and long-term management with respect to the real challenges and pressing need for an integrated nuclear waste management strategy.
The world is home to 435 nuclear reactors in 31 countries. The nuclear infrastructure present in the United States is aging, and almost all American nuclear facilities will have reached the end of their expected lifetimes by the middle of the century. The world currently has no long-term storage facilities, and all of the spent nuclear material is being stored at the facility where it was generated in the absence of waste storage—on the surface, in metal casks, or open pools. For decades, national and international bodies have known that this is a problem in need of solving. Throughout that time, the debate raged over precisely how and where to store this material in perpetuity.
Experts agree the end goal is remote and secure disposal in a long-term deep geologic repository. There are a number of geologic formations that might be used, including volcanic tuff, granite, salt and shale. Evaluation of potential sites must also consider social factors. A proper assessment looks far into the future and takes decades to complete. Given this reality, the feasibility and desirability of establishing consolidated interim storage facilities is part of the debate.
Interim storage is a bridge between short- and long-term options, and is an appealing option because on-site storage facilities are reaching capacity. The fact that many of these facilities are reaching the end of their productive lifespan is another driving factor. Storage of radioactive waste has limited marginal costs while the facilities are open for business, but that benefit disappears following closure. This supports the development of a centralized facility with higher security and staffing budgets than would be possible if numerous smaller facilities are maintained. An alarming factor to consider is that as the radioactivity of the spent fuel diminishes, the non-proliferation protection that this provides to the plutonium also disappears. Non-proliferation protection is an interesting phenomenon, where difficult-to-control forms of radioactivity prevent material from being handled and perhaps misused. Interim storage is not without its drawbacks, however. Significant transport of the material would be required. And while local communities, which stand to benefit from the employment opportunities, stepped forward, there is significant opposition to facility siting at the state level where those benefits are far more disbursed.
Similar concerns block the development of long-term geologic disposal solutions. On top of these issues is the significant increase in uncertainty that accompanies the long time periods that engineers, risk assessment professionals, and government officials are compelled to contend. The natural risks include tectonic activity and gas buildup. The performance of engineered barriers to mobilization of the nuclear material is similarly uncertain. Complex mathematical models are used to assess the performance of different options, but the long time-scales which must be considered, stretch the capacity of scientific understanding.
Given the magnitude of concerns surrounding long-term on-site storage, the authors suggest the pursuit of an interim storage option. They stress the importance of forthright communication of the uncertainties to communities that stand to be affected by these decisions. The authors comment that when examined in isolation, none of these options may at first appear desirable. We must realize, however, that to take no action is a decision in itself with consequences.