The US Department of Energys̀ (DOE) Office of Civilian Radioactive Waste Management (OCRWM), created with the enactment of the Nuclear Waste Policy Act of 1982 (NWPA), is tasked to accept and dispose of the nations̀ high-level radioactive waste and spent nuclear fuel in a deep geologic repository (high-level radioactive waste program). The report summarizes significant site characterization activities during the period from April 1, 1997 through September 30, 1997, in the evaluation of Yucca Mountain as a potential site for the geologic disposal of spent nuclear fuel and high-level radioactive wastes. The progress report also cites technical reports and research products that provide the detailed information on these activities. Chapter 2 outlines technical and regulatory issues that must be addressed by the Project and planned work toward achieving future objectives concerning the viability assessment, the environmental impact statement, the site recommendation, and the license application. Chapter 3 describes technical progress in preclosure radiological safety analysis, postclosure performance assessment, and performance confirmation activities. Chapter 4 describes various aspects of repository and waste package design and construction. It also discusses the Exploration Studies Facility cross drift. Chapter 5 describes site characterization activities, and Chapter 6 contains a complete list of references.

The report is the sixteenth in a series issued approximately every six months to report progress and results of site characterization activities being conducted to evaluate Yucca Mountain as a possible geologic repository for the disposal of spent nuclear fuel and high-level radioactive waste. This report highlights work started, in progress, and completed during the reporting period. In addition, this report documents and discusses changes to the Office of Civilian Radioactive Waste Management (OCRWM) Site Characterization Program (Program) resulting from the ongoing collection and evaluation of site information, systems analyses, development of repository and waste package designs, and results of performance assessment activities. Details on the activities summarized can be found in the numerous technical reports cited throughout the progress report. Yucca Mountain Site Characterization Project (Project) activities this period focused on implementing the near-term objectives of the revised Program Plan issued last period. Near-term objectives of the revised Program Plan include updating the US Department of Energys̀ (DOE) repository siting guidelines to be consistent with a more focused performance-driven program; supporting an assessment in 1998 of the viability of continuing with actions leading to the licensing of a repository; and if the site is suitable, submittal of a Secretarial site recommendation to the President in 2001 and license application the US Nuclear Regulatory Commission (NRC) in 2002. During this reporting period, the Project developed and baselined its long-range plan in December 1996. That revision reflected the detailed fiscal year (FY) 1997 work scope and funding plan previously baselined at the end of FY 1996. Site characterization activities have been focused to answer the major open technical issues and to support the viability assessment.

During the second half of fiscal year 1996, activities at the Yucca Mountain Site Characterization Project (Project) supported the objectives of the revised Program Plan released this period by the Office of Civilian Radioactive Waste Management of the US Department of Energy (Department). Outlined in the revised plan is a focused, integrated program of site characterization, design, engineering, environmental, and performance assessment activities that will achieve key Program and statutory objectives. The plan will result in the development of a license application for repository construction at Yucca Mountain, if the site is found suitable. Activities this period focused on two of the three near-term objectives of the revised plan: updating in 1997 the regulatory framework for determining the suitability of the site for the proposed repository concept and providing information for a 1998 viability assessment of continuing toward the licensing of a repository. The Project has also developed a new design approach that uses the advanced conceptual design published during the last reporting period as a base for developing a design that will support the viability assessment. The initial construction phase of the Thermal Testing Facility was completed and the first phase of the in situ heater tests began on schedule. In addition, phase-one construction was completed for the first of two alcoves that will provide access to the Ghost Dance fault.

In accordance with requirements of Section 113(b)(3) of the Nuclear Waste Policy Act of 1982, as amended, and 10 CFR 60.18(g), the U.S. Department of Energy has prepared this report on the progress of site characterization activities at Yucca Mountain, Nevada, for the period April 1, 1993, through September 30, 1993. This report is the ninth in a series issued at intervals of approximately six months during site characterization of Yucca Mountain as a possible site for a geologic repository for the permanent disposal of high-level radioactive waste. Also included in this report are activities such as public outreach and international programs that are not formally part of the site characterization process. Information on these activities is provided to report on all aspects of the Yucca Mountain studies.