The “safety case” approach has been developed to address the issue of evaluating the performance of a geologic repository in the face of the large uncertainty that results for evaluations that extend over hundreds of thousands of years. This paper reviews the concept of the safety case as it has been defined by the international community. We contrast the safety case approach with that presently used in the U.S. repository program. Especially, we focus on the role of uncertainty quantification.
The final disposal of nuclear waste is at the interface between the technologies of the nuclear fuel cycle that produce the waste and the natural hydrologic and geochemical cycles of geologic repositories. Despite this broad interdisciplinary scope, nuclear waste management, as practiced, remains “balkanized” among the relevant disciplines.
The U.S. government has worked for decades and spent tens of billions of dollars in search of a permanent resting place for the Nation’s nuclear waste. Some 80,000 tons of highly radioactive spent fuel from commercial nuclear power plants and millions of gallons of high-level nuclear waste from defense programs are stored in pools, dry casks and large tanks throughout the country at more than 75 sites in 39 states.
Abstract: We present a new perspective on geological disposal systems for nuclear waste. Geological disposal systems encompass all the processes required for the permanent isolation of highly-radioactive materials from humans and the biosphere. Radioactive materials requiring geological disposal are created by commercial nuclear power plants, research reactors, and defense-related nuclear activities, such as spent nuclear fuel from commercial reactors and high-level waste from reprocessing to reclaim fissile material for weapons.
Highly radioactive cesium-rich microparticles (CsMPs) were released from the Fukushima Daiichi nuclear power plant (FDNPP) to the surrounding environment at an early stage of the nuclear disaster in March of 2011; however, the quantity of released CsMPs remains undetermined.
For the past 15 years, the Waste Isolation Pilot Plant (WIPP) has stored transuranic waste from the US nuclear-defense programme. The facility, located 650 meters below ground in the bedded salt deposits of southeastern New Mexico, is run by the US Department of Energy (DOE) and will be permanently sealed in 2033. Yet an arms-control agreement made with Russia in 2000 requires the United States to dispose of 34 tonnes of weapons plutonium, which a recent DOE panel recommended should be stored at WIPP.
In a commentary on the long-term storage of SNF in the March 2015 issue of Nature Materials, Professor Rod Ewing writes that, "to design reliable and safe geological repositories it is critical to understand how the characteristics of spent nuclear fuel evolve with time, and how this affects the storage environment.
CISAC Affiliate Rodney Ewing, Chairman of the U.S. Nuclear Waste Technical Review Board and Professor at the University of Michigan, testified before the Subcommittee on Energy and Water Development of the U.S. House of Representatives.
In this testimony, he discusses the approval process for disposal of nuclear waste, what can be learned from the failure of the Yucca Mountian Project and other nuclear waste projects globally.
The primary waste form resulting from nuclear energy production is spent nuclear fuel (SNF). There are a number of different types of fuel, but they are predominantly uranium based, mainly UO2 or, in some cases, metallic U. The UO2 in SNF is a redox-sensitive semiconductor consisting of a fine-grained (5–10 μm), polycrystalline aggregate containing fission-product and transuranium elements in concentrations of 4 to 6 atomic percent. The challenge is to predict the long-term behavior of UO2 under a range of redox conditions.