The wastes in Hanford’s 177 underground tanks are a by-product of more than 50 years of nuclear weapons production. (Fig. 1 shows a typical tank farm under construction.) Storing, managing, and cleaning up these wastes pose many challenges. Some tanks, for example, contain flammable gas or potentially combustible organic compounds. Injected into the tanks as liquids, the wastes have assumed a variety of forms as they have settled and recombined over the years. These forms include sludge and a hard “saltcake” that may have to be pulverized before it can be removed from the tanks. Wastes in at least 67 single-shell tanks have leaked or are assumed to have leaked into the ground as the concrete-and-steel structures have deteriorated. DOE’s program for addressing these wastes, called the Tank Waste Remediation System, calls for a series of actions to chemically characterize the waste in the tanks, remove it from the tanks, and prepare it for permanent disposal during the several hundred thousand years in which some of it will remain dangerously radioactive. This program is expected to cost $36 billion over its life-cycle. Waste characterization is the first major action. Since fiscal year 1989, the first year for which reliable cost data exist, DOE has spent about $260 million on characterization. The purpose of characterization is to provide sufficient information for safe storage of the waste in the tanks while awaiting the development of processes for remediating it, as well as for designing the steps of the remediation process itself. These steps include removing the wastes (retrieval), separating them into low-level and high-level portions (pretreatment), treating them (vitrification), and preparing them for permanent disposal. DOE began characterizing the waste in Hanford’s tanks in 1985. Since then, its efforts have repeatedly fallen behind schedule. DOE’s March 1994 schedule resulted from the renegotiation of an agreement originally signed in 1989. This Tri-Party Agreement with Washington State’s Department of Ecology (Ecology) and EPA initially called for completing the characterization of single-shell tanks by 1998. DOE subsequently found itself unable to comply with the characterization deadline and renegotiated the agreement. The revised Tri-Party Agreement calls for characterizing all 177 tanks for retrieval, pretreatment, treatment, and disposal by September 1999. In a separate agreement to address concerns raised by the Defense Nuclear Facilities Safety Board, an independent executive-branch oversight body, DOE agreed to another set of characterization requirements related primarily to the safe storage of the waste. Under this agreement, DOE was to characterize the 54 “watchlist” tanks—those with known or suspected safety problems, such as potential flammability—by October 1995 and to sample and assess safety conditions associated with all 177 tanks by October 1996. DOE and Westinghouse have made limited progress in meeting the agreed-upon deadlines for characterization. Despite some recent improvements in sampling capability, Westinghouse remains behind schedule in taking samples from the tanks. Its responses to reporting requirements have consisted mainly of summarizing previously known information about the tanks’ contents. In September 1995, DOE acknowledged that the Tri-Party Agreement and Safety Board characterization deadlines could not be met and proposed a two-phased approach for characterizing tank wastes that would extend characterization activities well beyond 1999. As of the time we completed our work, however, DOE had not formally notified Ecology that it could not meet the Tri-Party Agreement deadlines. DOE and Westinghouse have made limited progress in meeting the Safety Board and Tri-Party agreement deadlines (see fig. 2). The Safety Board agreement called for taking and analyzing about 216 of 408 core samplesby September 30, 1995. As of that date, Westinghouse had completed 42. The Safety Board agreement also called for taking core samples from all 54 watchlist tanks by October 1995; by that date, Westinghouse had obtained core samples from 10 watchlist tanks. At Westinghouse’s current estimated sampling pace, all 408 core samples will not be done until 2002—more than 5 years after the agreement’s October 1996 deadline. Similarly, while the revised Tri-Party Agreement calls for full characterization of tank wastes by September 1999, DOE’s recent planning documents show that at the current sampling pace, DOE does not expect to meet this requirement until September 2004. Westinghouse has shown some improvement in its ability to take core samples. In fiscal year 1994, Westinghouse completed only 3 of 13 planned core samples, but in fiscal year 1995, it completed 39—the same number it had estimated it would be able to take. However, the 39 were concentrated in fewer tanks than Westinghouse had planned. Westinghouse currently estimates that it will be able to take about four core samples per month through March 1996 and five per month thereafter. During fiscal years 1994 through 1995, Westinghouse also used other types of samples besides core samples to augment its understanding of tank wastes, completing 177 of 210 planned samples. These other methods yield results that are generally considered less comprehensive than core samples, because they usually do not involve a top-to-bottom sampling of the waste. However, the results of these samples can supplement what is learned from core samples because they can provide information on tank vapors and liquids that core samples may not provide. Even with these other efforts, to date no tank has yet been sufficiently characterized either to meet the Safety Board’s sampling requirements or to support any of the subsequent steps in the waste treatment process. The Director of DOE’s characterization division said that he was unable to estimate when the characterization of any tank would be completed. DOE and Westinghouse officials believe that characterization difficulties are not affecting the safe storage of tank wastes. According to the assistant manager of DOE’s tank waste remediation program, Westinghouse has placed controls on tank farm operations to reduce the risk of an unintentional release. The controls include using sparkless equipment and avoiding certain types of drilling procedures. However, these controls have made it more difficult for DOE to maintain its desired sampling rate. DOE and Westinghouse characterization managers have acknowledged that they will not meet the Safety Board or Tri-Party Agreement deadlines. They have prepared a draft revision of the original implementation plan agreed to with the Safety Board. This draft, which does not specify a completion date, is discussed in more detail in the next section. DOE and Westinghouse also acknowledged the need to propose changes to the Tri-Party Agreement, but at the time we completed our work, they had not yet submitted a formal proposal to Ecology or EPA. However, Ecology has informed DOE and Westinghouse that in the state’s view, the inability to obtain adequate samples does not provide sufficient grounds for renegotiating the characterization milestones of the Tri-Party Agreement. Ecology expects DOE to formulate a plan to compensate for past inadequacies and to meet commitments under the current Tri-Party Agreement schedule. The revised Tri-Party Agreement requires DOE to submit, for Ecology’s approval, characterization reports on a certain number of tanks each year through 1999. All 23 of the reports submitted through fiscal year 1994 were based mostly on existing “historical” data about the wastes, supplemented with limited sampling results. The 30 reports submitted on September 30, 1995, were also based primarily on historical information, although they contained some results of samples taken since May 1989. Reaction to the value of these reports is mixed. DOE accepted the reports, but Ecology, the body that must approve the reports, has criticized their contents, including Westinghouse’s extensive reliance on historical information. Rather than approve the 23 reports submitted in fiscal years 1993 and 1994, Ecology received them on the condition that Westinghouse develop additional characterization data and resubmit the reports for approval within 2 years. In connection with the fiscal year 1995 reports, Ecology’s characterization team leader said that 25 of the 30 reports were inadequate because they contained mainly historical information, modeling results that had not been verified, and limited analytical results. He considered the results of the analyses of the most recent samples insufficient because they were limited to determining whether tank wastes were being maintained in a safe condition and did not contribute to any remediation step. While many factors have contributed to the slow pace of the characterization effort, the primary reasons for slow progress are that (1) DOE and Westinghouse have not yet determined how to successfully draw reliable samples and characterize the waste and (2) managerial weaknesses with the characterization program and other aspects of the tank farms have exacerbated delays and contributed to operational inefficiencies. DOE and Westinghouse have been unable to develop and implement a characterization approach that has been successful in meeting the requirements of the Tri-Party Agreement or their commitments to the Safety Board. Three different approaches have been attempted since the Tri-Party Agreement was signed in 1989, and in each case, the approach has not been successfully implemented. As a result, DOE and Westinghouse are still having difficulty answering fundamental methodological questions that have existed since the characterization program began: how to take reliable samples, what types of and how much sampling data to gather, and how to reliably predict the waste constituents on the basis of sampling and other data. Limited progress in taking samples has led DOE and Westinghouse to search for another characterization approach that would satisfy the requirements of the Tri-Party Agreement as well as their commitments to the Safety Board. The latest approach, proposed in September 1995, aims to evaluate the program on a continuing basis while taking samples and collecting data, rather than following a fixed schedule. DOE now views sampling as an iterative process in which the total number of samples needed depends on the results of the initial samples taken. This viewpoint is in contrast to DOE’s earlier strategy that required a fixed number of samples. DOE’s latest characterization strategy has two phases: Phase one concentrates primarily on ensuring safe storage while demonstrating the approach’s overall validity.