For making a PA, USNRC regulations place emphasis on siting criteria, and, in particular, recognize the importance of ground water flow as a contaminant transport mechanism (10CFR61, Subpart D). USNRC regulations state that "site characteristics should be considered in terms of the indefinite future and evaluated for at least a 500-year time frame" (10CFR61.7). Recent USNRC documents suggest that a 10,000-year horizon may be an appropriate end point for PA studies covering the disposal system for low-level mixed waste (USNRC, 1997). As will be discussed in Chapters 5 and 6, there are no available tests that can reasonably predict the very long-term performance of waste forms. As a result, performance assessments often take little credit for retention of long-lived radionuclides by the waste form.

In compliance with the FFCA, DOE regulates cleanup and waste disposal at its sites through implementation of internal orders based on its authority under the AEA. These orders include the following:

• DOE Order 5400, General Environmental Protection (DOE, 1998a); and
• DOE Order 5820, Radioactive Waste Management.

DOE is required to manage its mixed wastes in a manner that assures the health and safety of site operating personnel and the public, and protection of the environment. Waste treatment must minimize the generation of secondary wastes and comply with all applicable federal, state, and local environmental, health, and safety laws and regulations.

DOE Order 5400.5 sets radiation exposure standards for the public and on-site personnel. These standards permit a total of 100 millirem per year (mrem/yr) exposure to an individual member of the public. Of this total, only 10 mrem/yr can result from inhalation of airborne particles, and exposure from ingesting radionuclides in drinking water is limited to 4 mrem/yr¹³ Any disposed radioactive or mixed waste

Front Matter (R1-R10)

Executive Summary (1-5)

1. Introduction (6-12)

2. Inventory and Characteristics of DOE Mixed Waste (13-21)

3. Mixed Waste Regulations (22-40)

4. Waste Treatment and Stabilization (41-69)

5. Characterization of Mixed Waste Forms (70-82)

6. Role of the Waste Form in Performance Assessment (83-96)

7. Findings and Recommendations (97-105)

References (106-112)

Appendix A: Statement of Task (113-113)

Appendix B: Information Used by the Committee During Its Review (114-117)

Appendix C: Technology Needs Identified by the MWFA (118-122)

Appendix D: Biographical Sketches of Committee Members (123-126)

Apendix E: Acronyms and Definitions (127-129)