Once the bulk of the radioactive waste is removed from tanks at the Savannah River Site, DOE plans to fill the tanks with grout to close most of them permanently. But given that the small amount of residual waste left in the tanks has a much lower likelihood of causing significant radioactive contamination of the environment, the department need not rush to grout all the tanks -- a step that is practically irreversible. Instead, the committee urged DOE and South Carolina to decouple the schedules for cleaning the tanks and sealing them, timelines that appear to be linked under a Federal Facility Agreement. Doing so will allow DOE to use emerging technologies to enhance tank cleanup, improve how the residual waste is immobilized, and better prevent water from seeping into closed tanks.
On the other hand, tank closure does not have to be delayed if there is very little residual waste or if special circumstances warrant closure, the committee said. It added that revising the closure schedule for tanks with insoluble wastes does not need to affect previously agreed-upon milestones for final closing of the tanks. In fact, if new technologies become available, they may speed up tank cleanup and closure, possibly leaving less waste behind.
The Savannah River Site also faces what DOE calls a crisis in the amount of compliant tank space available to store waste from ongoing operations at the site, including tank cleanup itself. Tanks are considered compliant if they have a secondary containment system, so that they are essentially tanks within tanks; noncompliant tanks have no second wall or only a partial one. A certain amount of compliant space also must be reserved for an emergency, such as a tank leak.
The committee agreed that the lack of compliant space is a major problem, but questioned DOE's plans for freeing up space in existing tanks. DOE plans to use a physical separation process to remove radioactivity from some salt wastes, and then grout and permanently store those wastes in on-site vaults. But the committee noted that while waste from this process represents only 8 percent of the volume of radioactive waste to be generated during salt-waste processing, the waste contains 80 percent to 90 percent of the radioactivity projected to be in the vaults. Chemical processes that can remove more radioactivity from salt wastes are scheduled to begin in 2007 and 2009. Until then, DOE should consider other options for preserving or better utilizing its limited compliant tank space, such as setting aside carefully selected nonleaking, noncompliant tanks for emergency storage, or reducing waste streams to compliant tanks.
In a follow-up report expected early next year, the committee will further evaluate environmental risks at the Savannah River Site and examine DOE's plans for managing radioactive tank wastes at sites in Idaho and Washington state.
The study was sponsored by the U.S. Department of Energy. The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering. It is a private, nonprofit institution that provides science and technology advice under a congressional charter. A committee roster follows.
Copies of TANK WASTES PLANNED FOR ONSITE DISPOSAL AT THREE DEPARTMENT OF ENERGY SITES: THE SAVANNAH RIVER SITE will be available from the National Academies Press; tel. 202-334-3313 or 1-800-624-6242 or on the Internet at HTTP:/
[ This news release and report are available at HTTP:/
NATIONAL RESEARCH COUNCIL
Division on Earth and Life Studies
Board on Radioactive Waste Management
COMMITTEE ON THE MANAGEMENT OF CERTAIN RADIOACTIVE WASTE STREAMS
STORED IN TANKS AT THREE DEPARTMENT OF ENERGY SITE
FRANK L. PARKER* (CHAIR)
Distinguished Professor of Civil and Environmental Engineering
HADI A. ABU-AKEEL*
JOHN S. APPLEGATE
Associate Dean for Academic Affairs and Walter W. Foskett Professor of Law
Indiana University School of Law
Associate Professor of Mechanical Engineering and Robotics
Department of Mechanical Engineering
Carnegie Mellon University
PAUL P. CRAIG
Emeritus Professor of Engineering
University of California
ALLEN G. CROFF
Senior Technical Staff Member
Oak Ridge National Laboratory (retired)
Oak Ridge, Tenn.
PATRICIA J. CULLIGAN
Associate Professor of Civil Engineering and Engineering Mechanics
New York City
Radiochemistry Ph.D. Program, and
Department of Chemistry
University of Nevada
RACHAEL J. DETWILER
Braun Intertec Corp.
EDWIN E. HERRICKS
Professor of Environmental Biology
Department of Civil and Environmental Engineering
University of Illinois
TISSA H. ILLANGASEKARE
AMAX Distinguished Chair of Environmental Sciences and Engineering;
Professor of Civil Engineering; and
Center for the Experimental Study of Subsurface Environmental Processes
Colorado School of Mines
Menlo Park, Calif.
PAUL A. LOCKE
Environmental Health Sciences
Center for Alternatives to Animal Testing, and Risk Sciences and Public Policy Institute
Bloomberg School of Public Health
Johns Hopkins University
DIANNE R. NIELSON
Utah Department of Environmental Quality
Salt Lake City
KALATHIL E. PHILIPOSE
Decommissioning and Waste Management Business Unit
Chalk River Nuclear Laboratories
Atomic Energy of Canada Ltd.
Deep River, Ontario
ALFRED P. SATTELBERGER
Research Fellow and Former Director
Office of Science Programs, and
Science and Technology Base Program Office
Los Alamos National Laboratory
Los Alamos, N.M.
ANNE E. SMITH
Charles River Associates
J. LESLIE SMITH
Cominco Chair in Minerals and the Environment
University of British Columbia
DONALD W. STEEPLES
Dean A. McGee Distinguished Professor of Applied Geophysics
Department of Geology
University of Kansas
RESEARCH COUNCIL STAFF
* Member, National Academy of Engineering