Since plutonium production ended at the Hanford Site in the late 1980s, DOE has focused on cleaning up the radioactive and hazardous waste accumulated at the site. It has established an approach for stabilizing, treating, and disposing of the site’s tank wastes. Its planned cleanup process involves removing, or retrieving, waste from the tanks; treating the waste on site; and ultimately disposing of the lower-activity radioactive waste on site and sending the highly radioactive waste to a geologic repository for permanent disposal. As cleanup has unfolded, however, the schedule has slipped, and the costs have mounted. According to DOE’s latest estimate in June 2008, treatment of the waste is not expected to begin until late 2019 and could continue until 2050 or longer. The following two figures show a tank farm and construction of waste treatment plant facilities at the Hanford Site. Most of the cleanup activities at Hanford, including the emptying of the underground tanks, are carried out under the Hanford Federal Facility Agreement and Consent Order among DOE, Washington State’s Department of Ecology, and the federal Environmental Protection Agency. Commonly called the Tri-Party Agreement, this accord lays out legally binding milestones for completing the major steps of Hanford’s waste treatment and cleanup processes. The agreement was signed in May 1989 and has been amended a number of times since then. A variety of local and regional stakeholders, including county and local governmental agencies, citizen and advisory groups, and Native American tribes, also have long- standing interests in Hanford cleanup issues. Two primary contractors are carrying out these cleanup activities; one is responsible for managing and operating the tank farms, and the other for constructing the facilities to treat the tank waste and prepare it for permanent disposal. During our review, these contractors were CH2M Hill and Bechtel, respectively. Both contracts are cost-reimbursement contracts, which means that DOE pays all allowable costs. In addition, the contractors can also earn a fee, or profit, by meeting specified performance objectives or measures. Applicable DOE orders and regulations are incorporated into these contracts, either as distinct contract clauses or by reference. For example, contractors are required to use an accounting system that provides consistency in how costs are accumulated and reported so that comparable financial transactions are treated alike. Such a system is to include consistent practices for determining how various administrative costs are assessed or how indirect costs for labor are calculated. Contractors also are required to implement an integrated safety management system, a set of standardized practices that allow the contractor to identify hazards associated with a specific scope of work, to establish controls to ensure that work is performed safely, and to provide feedback that supports continuous improvement. The system, which allows contractors to stop work when conditions are unsafe, is intended to instill in everyone working at the site a sense of responsibility for safety. This policy is reinforced by labor agreements between the contractor and its workforce that explicitly allow work stoppages as needed for safety and security reasons. With few exceptions, DOE’s sites and facilities are not regulated by the Nuclear Regulatory Commission or by the Occupational Safety and Health Administration. Instead, DOE provides internal oversight at several different levels. DOE’s Office of River Protection oversees the contractors directly. In addition, the Office of Environmental Management provides funding and program direction. DOE’s Office of Enforcement and other oversight groups within the Office of Health, Safety, and Security oversee contractors’ activities to ensure nuclear and worker safety. Finally, the Defense Nuclear Facilities Safety Board, an independent oversight organization created by Congress in 1988, provides advice and recommendations to the Secretary of Energy to help ensure adequate protection of public health and safety. DOE officials reported that from January 2000 through December 2008, work on the Hanford tank farms and the waste treatment plant temporarily stopped at least 31 times to address various safety or construction concerns. These work stoppages ranged in duration from a few hours to more than 2 years, yet little supporting documentation of these occurrences exists. DOE reported that of the 31 work stoppages, 12 occurred at the tank farms and 19 at the waste treatment plant. Sixteen of the work stoppages reportedly resulted from concerns about safety. A complete listing of these work stoppages is included in appendix II. These work stoppages were initiated to respond directly to an event in which property was damaged or a person injured, or they addressed an unsafe condition with the potential to harm workers in the future. Four of these work stoppages were relatively brief, lasting less than 2 days, and were characterized by DOE and officials as proactive safety “pauses.” For example, in October 2007, after a series of slips, trips, or falls during routine activities, contractor managers stopped work at the waste treatment plant site for 1 hour to refresh workers’ understanding of workplace hazards. The following two examples, for which supporting documentation was available, illustrate the types of work stoppages occurring at the Hanford Site because of safety concerns: Controlling worker exposure to tank farm vapors. Beginning in 2002, as activities to transfer waste from leak-prone, single-shell tanks to more secure double-shell tanks disturbed tank contents, the number of incidents increased in which workers complained of illnesses, coughing, and skin irritation after exposure to the tank vapors. The Hanford underground storage tanks contain a complex variety of radioactive elements and chemicals that have been extensively mixed and commingled over the years, and DOE is uncertain of the specific proportions of chemicals contained in any one tank. These constituents generate numerous gases, such as ammonia, hydrogen, and volatile organic compounds, which are purposely vented to release pressure on the tanks, although some gases also escape through leaks. During the 1990s, the tank farm contractor evaluated potential hazards and determined that if workers around the tanks used respirators, they would be sufficiently protected from harmful gases. DOE reported in 2004, however, that disturbing the tank waste during transfers had changed the concentration of gases released in the tanks and that no standards for human exposure to some of these chemicals existed. To protect workers’ health, in 2004 the tank farm contractor equipped workers with tanks of air like those used by firefighters. Work at the tank farms stopped intermittently for about 2 weeks as a result, in part because the contractor had to locate and procure sufficient self-contained air and equipment for all workers. Accidental spill of radioactive and chemical wastes at tank S-102. In July 2007, as waste was being pumped out of a single-shell to a double-shell tank, about 85 gallons of waste was spilled. DOE has been gradually emptying waste from Hanford’s single-shell tanks into double-shell tanks in preparation for treatment and permanent disposal, but because the tank waste contains sludge and solids, waste removal has been challenging. Because the tanks were not designed with specific waste retrieval features, waste must be retrieved through openings, called risers, in the tops of the tanks; technicians must insert specially designed pumps into the tanks to pump the waste up about 45 to 60 feet to ground level. DOE has used a variety of technologies to loosen the solids, including sprays of acid or water to help break up the waste and a vacuum-like system to suck up and remove waste through the risers at the top. On July 27, 2007, during retrieval of radioactive mixed waste from a 758,000-gallon single-shell tank, a pump failed, spilling 85 gallons of highly radioactive waste to the ground. At least two workers were exposed to chemical vapors, and later several workers reported health effects they believed to be related to the spill. Retrieval operations for all single-shell tanks were suspended after the accident, and DOE did not resume operations until June 2008, a delay of 1 year, while the contractor cleaned up the spill and DOE and the contractor investigated the accident to evaluate the cause, the contractor’s response, and appropriate corrective action. DOE officials reported that the remaining 15 work stoppages resulted from concerns about construction quality and involved rework to address nuclear safety or technical requirements that had not been fully met, such as defective design, parts fabrication and installation, or faulty construction. For example: Outdated ground-motion studies supporting seismic design of the waste treatment plant. In 2002, the Defense Nuclear Facilities Safety Board began expressing concerns that the seismic standards used to design the waste treatment facilities were not based on the most current ground- motion studies and computer models or on the geologic conditions present directly beneath the construction site. After more than 2 years of analysis and discussion, DOE contracted for an initial seismic analysis, which confirmed the Defense Nuclear Facilities Safety Board’s concerns that the seismic criteria were not sufficiently conservative for the largest treatment facilities—the pretreatment facility and the high-level waste facility. Revising the seismic criteria caused Bechtel to recalculate thousands of engineering estimates and to rework thousands of design drawings to ensure that tanks, piping, cables, and other equipment in these facilities were adequately anchored. Bechtel determined that the portions of the building structures already constructed were sufficiently robust to meet the new seismic requirements. By December 2005, however, Bechtel estimated that engineering rework and other changes to tanks and other equipment resulting from the more conservative seismic requirement would increase project costs substantially and add as much as 26 months to the schedule. Ultimately, work on the two facilities was suspended for 2 years, from August 2005 until August 2007. About 900 workers were laid off as a result. DOE does not routinely collect or formally report information about work stoppages, in part because federal regulations governing contracts do not require contractors to track work stoppages and the reasons for them. While federal acquisition regulations do require that contractors implement a reliable cost-accounting system, the regulations do not require contractors to centrally collect information on the specific circumstances surrounding a work stoppage.