The Hanford Site (also known as the Hanford Reservation) occupies approximately 1,450 km2 (560 square miles) along the Columbia River in south-central Washington, north of the city of Richland. The site was established by the federal government in 1943 to produce plutonium for nuclear weapons. Currently, the mission of the site, under the responsibility of the U.S. Department of Energy (DOE), is management of wastes generated by the weapons program and remediation of the environment contaminated by that waste. As part of that mission, DOE and the State of Washington Department of Ecology prepared the Hanford Site Tank Waste Remediation System Draft Environmental Impact Statement (DEIS). The Hanford Tanks is a general review of the DEIS. Its findings and recommendations are the subject of this report. Selection of a disposition plan for these wastes is a decision of national importance, involving potential environmental and health risks, technical challenges, and costs of tens to hundreds of billions of dollars. The last comprehensive analysis of these issues was completed 10 years ago, and several major changes in plans have occurred since. Therefore, the current reevaluation is timely and prudent. This report endorses the decision to prepare this new environmental impact statement, and in particular the decision to evaluate a wide range of alternatives not restricted to those encouraged by current regulatory policies.

DOE Tank Waste: How clean is clean enough? The U.S. Congress asked the National Academies to evaluate the Department of Energy's (DOE's) plans for cleaning up defense-related radioactive wastes stored in underground tanks at three sites: the Hanford Site in Washington State, the Savannah River Site in South Carolina, and the Idaho National Laboratory. DOE plans to remove the waste from the tanks, separate out high-level radioactive waste to be shipped to an off-site geological repository, and dispose of the remaining lower-activity waste onsite. The report concludes that DOE's overall plan is workable, but some important challenges must be overcomeâ€"including the removal of residual waste from some tanks, especially at Hanford and Savannah River. The report recommends that DOE pursue a more risk-informed, consistent, participatory, and transparent for making decisions about how much waste to retrieve from tanks and how much to dispose of onsite. The report offers several other detailed recommendations to improve the technical soundness of DOE's tank cleanup plans.

A major issue in the cleanup of this country's nuclear weapons complex is how to dispose of the radioactive waste resulting primarily from the chemical processing operations for the recovery of plutonium and other defense strategic nuclear materials. The wastes are stored in hundreds of large underground tanks at four U.S. Department of Energy (DOE) sites throughout the United States. The tanks contain hundreds of thousands of cubic meters of radioactive and hazardous waste. Most of it is high-level waste (HLW), some of it is transuranic (TRU) or low- level waste (LLW), and essentially all containing significant amounts of chemicals deemed hazardous. Of the 278 tanks involved, about 70 are known or assumed to have leaked some of their contents to the environment. The remediation of the tanks and their contents requires the development of new technologies to enable cleanup and minimize costs while meeting various health, safety, and environmental objectives. While DOE has a process based on stakeholder participation for screening and formulating technology needs, it lacks transparency (in terms of being apparent to all concerned decision makers and other interested parties) and a systematic basis (in terms of identifying end states for the contaminants and developing pathways to these states from the present conditions). An End State Methodology for Identifying Technology Needs for Environmental Management, with an Example from the Hanford Site Tanks describes an approach for identifying technology development needs that is both systematic and transparent to enhance the cleanup and remediation of the tank contents and their sites. The authoring committee believes that the recommended end state based approach can be applied to DOE waste management in general, not just to waste in tanks. The approach is illustrated through an example based on the tanks at the DOE Hanford Site in southeastern Washington state, the location of some 60 percent by volume of the tank waste residues.