THE DOE'S CARLSBAD AREA OFFICE INTERNATIONAL
COOPERATIVE SCIENTIFIC STUDIES
Mark Matthews
U.S. Department of Energy
Carlsbad Area Office, P.O. Box 3090
Carlsbad, New Mexico, 88221, USA
505 234 7467; matthem@wipp.carlsbad.nm.us
Kurt Larson
Sandia National Laboratories
P.O. Box 5800
Albuquerque, New Mexico, 87185-1335, USA
505 848 0862; kwlarso@sandia.gov
Wendell Weart
Sandia National Laboratories
P.O. Box 5800
Albuquerque, New Mexico, 87185-1337, USA
505 848 0788; wdweart@sandia.gov
ABSTRACT
The U.S. Department of Energy (DOE) expects to receive a Certification of Compliance for the Waste Isolation Pilot Plant (WIPP) from the Environmental Protection Agency (EPA) in the Spring of 1998 and commence disposal operations shortly thereafter. During the disposal phase, continued investigations into certain scientific issues will allow DOE's Carlsbad Area Office (CAO) to develop more detailed knowledge which could enhance WIPP operations and performance. This is true of activities which will be conducted over the life of the operation (e.g., backfill, and waste characterization and emplacement) or implemented late in the operational life (seals). Also, improved knowledge of fluid flows in geologic media and the applicability of flow models to predict that flow could allow a reduction in the conservative approximations, now utilized in performance assessment, when the required five-year recertifications are conducted. An important element of continued CAO scientific studies is the participation in joint international studies which are concerned with the issues of direct relevance to WIPP. As part of the international research and development (IR&D) program, the CAO is involved in seals experiments in Canada and is exchanging information on backfill and seals with Germany. CAO is also participating in other collaborative efforts, such as the Phase V experiments at the Grimsel test site in Switzerland. CAO's involvement is in modeling two-phase flow, tracer studies in fractured media, colloid and radionuclide speciation studies, and analyses and evaluation of earlier studies in the fractured disturbed rock zone. The WlPP flow laboratory capabilities may be applied to laboratory-size samples. The CAO may engage in joint activities with other nations, such as Sweden, the United Kingdom, and Japan. The CAO also participates in Organization for Economic Cooperation and Development (OECD)/Nuclear Energy Agency (NEA) working groups. Continued involvement with the international waste management community and the related test programs is resulting in mutually beneficial scientific experimental projects.
INTRODUCTION
The CAO administers the WIPP site, which hosts a deep geologic repository for safe disposal of U.S. defense-related TRU waste located 42 kilometers (km) east of Carlsbad, New Mexico (Figure 1), and manages the National Transuranic Waste Program (NTP), which oversees TRU waste management from generation to disposal. Upon completion of the current regulatory licensing phase, the WIPP is scheduled to begin receiving waste by June 1998.
Figure 1. Locations of the 10 Major TRU Radioactive-waste Generation Sites and the WIPP Repository.
The CAO's main programmatic responsibility during the pending disposal phase is to operate a safe, efficient TRU waste repository at the WIPP, to operate an effective system for management of TRU waste from generation to disposal, and to comply with applicable laws, regulations, DOE Orders, and permits. This responsibility requires maintenance and upgrades to the current technologies for TRU waste operations, monitoring, and transportation. This responsibility also requires the maintenance of scientific capabilities for evaluating the performance of the WIPP repository. This includes supporting probabilistic performance assessments with credible evidence of the nature and consequences of events and processes that may occur in the repository and the surrounding geological setting during the 10,000-year regulatory period. The CAO anticipates that international cooperative efforts will assist in the maintenance and advancement of the technological and scientific basis for the WIPP.
The WIPP site has been investigated and developed since 1974. Located within the WIPP site's 42-km2 set-aside area are surface and subsurface facilities designed to facilitate the safe handling and disposal of TRU waste. Approximately one-tenth of the underground waste disposal area has already been mined in a bedded salt formation at a depth of 650 meters (m) (Figure 2). Approximately 176,000 m3 of TRU waste containing about 12,000 kilograms of plutonium and other actinides will be emplaced in disposal rooms 4 m high, 10 m wide, and 91 m long. Magnesium oxide (MgO) backfill will be emplaced with the waste to control the actinide solubility and mobility in the disposal areas. Properties of the repository horizon have been investigated in an underground test facility excavated north of the waste disposal area, in which seals, rock mechanics, hydrology, and simulated waste emplacement tests were conducted. Geologic and hydrologic characterization of strata on the site have been conducted by surface-based boreholes and observations from the existing excavation.
Figure 2. Schematic Illustration of the WIPP Repository and the Geologic Stratigraphy at the Site.
The CAO is focusing on programs and activities specifically addressing the needs of the Disposal Phase Experimental Program (DPEP). In fulfilling some of the needs of the DPEP through international activities, the CAO receives and contributes significant added benefit to the general field of nuclear waste management. The DPEP supports required five-year regulatory recertifications and improvements to WIPP and national TRU system operations. The DPEP outlines the experimental program to be conducted by the CAO during the first five-year recertification period. The DPEP also forms the basis for longer term CAO activities to be carried out during the 35-year disposal phase. The main objectives of the DPEP (Figure 3) are to support:
Figure 3. Objectives of the Disposal Phase Experimental Program.
OBJECTIVES OF THE CAO INTERNATIONAL RESEARCH AND DEVELOPMENT PROGRAM
The primary CAO objectives of international collaboration are
In some areas of broad international interest, the CAO has developed a leading expertise through its 23-year WIPP repository and TRU waste characterization activities. In addition to participating in relevant and beneficial experiments, the CAO will provide the international community convenient access to this information by sponsoring and hosting symposia and workshops on relevant topics and by participation in international waste management organizations and topical meetings.
To advance its overall objectives, the CAO will seek partnerships in the following types of international exchanges and collaborations:
1. Activities providing specific information important to the CAO's mission, such as:
2. Activities in advancing scientific disciplines that are important to assessing the future behavior of the WIPP repository, such as:
3. Activities transferring information and technology developed by the CAO to the international community, such as:
The CAO will develop and facilitate international collaborations with its domestic contractors Westinghouse Waste Isolation Division and Sandia National Laboratories. In addition, the CAO encourages international collaboration with the Carlsbad Environmental Monitoring and Research Center (CEMRC). The CEMRC has a world-class laboratory with technical staff expertise in radiochemistry, environmental chemistry, mechanical engineering, atmospheric science, health physics, and dose assessments. It is currently pursuing international collaborations with the International Atomic Energy Agency (IAEA) in radiochemistry projects.
CRITERIA FOR INITIATING AND SUPPORTING INTERNATIONAL COOPERATIVE ACTIVITIES
The CAO has established specific criteria by which potential international activities will be evaluated. The CAO's criteria and their benefits are listed below:
To promote maximum exchange of information in collaborations among programs whose specific requirements differ, the CAO proposes a stringent policy that all technical work performed in international collaborations be subject to independent peer review. Independent peer review of technical work would be accomplished through:
CURRENT AND POTENTIAL INTERNATIONAL EXCHANGE ACTIVITIES
The CAO has developed and is continuing to develop collaborative efforts with other nations in the areas of seals/rock mechanics, hydrology/transport, and chemistry. The CAO is also engaging in cooperative activities with international organizations. A description of these current and potential activities is provided below in each of these major topical areas.
Seals and Rock Mechanics
As part of the Canadian Nuclear Fuel Waste Management Programme and in cooperation with other foreign waste management organizations, a major tunnel-sealing experiment is to be completed over the next several years. The tunnel-sealing experiment's objectives are (1) to develop and study clay- and concrete-sealing technologies and (2) to evaluate the performance of a sealing system using these technologies. WIPP technologies to be used in the experiment may include clay block-making expertise and machinery, cementitious grouting experience, fluid-flow modeling, and seal-design experience. The CAO is collaborating with the German program at Morsleben and a private waste disposal effort at Salzefürth to investigate sealing technologies for drifts and disturbed rock zone performance in salt. Laboratory and field tests have been performed, and mechanical and hydrological behaviors have been investigated. The goal of these collaborations is enable reduction in the cost of WIPP seals through simplification as performance is demonstrated. At the Grimsel site in Switzerland, the CAO is participating as a reviewer in the documentation of the conclusions of the 10-year long Tunnel Near-Field program.
Hydrology/Transport
The CAO is actively searching for international collaborations to provide additional data about multi-rate transport that will be relevant to multi-rate transport models applied to the Culebra Dolomite, which is fractured and has heterogeneous pore structures. The CAO desires two collaborative efforts: one in fractured low porosity rock (crystalline or indurated sedimentary) and a second in fractured high porosity rock (sedimentary/argillaceous). These two conditions cover the range of porosity heterogeneity present in the Culebra Dolomite. The crystalline rock at the Grimsel site is appropriate for obtaining data and samples pertaining to fractured low-porosity rock. As part of the hyperalkaline plume in fractured rocks (HPF) experiment currently being planned, the CAO may conduct multi-rate transport experiments. The CAO has identified the crystalline rock present in Sweden's Äspö Hard Rock Laboratory as relevant to this type of experiment. Although a specific partner for collaboration in multi-rate transport in fractured high-porosity rocks has not been identified, the CAO understands that the Mont Terri facility in Switzerland may have an appropriate rock type (the Opalinas Clay) for this type of experiment, and access may be available in a few years. The CAO is planning to host a technical workshop or symposium on multi-rate transport in the upcoming year. The CAO will participate in the gas migration/two-phase flow experiment being conducted at Grimsel to investigate the two-phase flow behavior of rock in the vicinity of underground excavations.
Chemistry
The CAO is participating in the Grimsel HPF experiment, which investigates chemical precipitation reactions that may occur during transport of a hyperalkaline plume through fractured crystalline rock. Depending on plume chemistry and rock mineralogy and fabrics, these reactions may affect the diffusion and sorption properties of the rock. The CAO is interested in the HPF experiment because it will assist in the evaluation of the potential for such reactions to occur in the Culebra Dolomite, and the benefits (actinide co-precipitation) and detriments (reduced matrix diffusion) of such reactions on predictions of actinide transport in the Culebra Dolomite. The CAO is also active in the Grimsel colloid far-field retardation (CFR) experiment, in which simplified approaches to modeling colloid transport will be developed. Anticipated activities include microbial transport column experiments, actinide bioaccumulation approaches, microbe-contaminant association/dissociation experiments, and approaches for humic actinide complexation. The CAO is also active in the Grimsel in-situ speciation of redox-sensitive radionuclides (SRR) experiment, which is relevant to alkaline conditions present at WIPP. In May 1998, the CAO and the Environment Agency of England and Wales will co-host in Carlsbad an invitation-only technical workshop on the uses of cementitious backfill materials in repositories.
Collaborations Sponsored by International Organizations
The CAO is an ongoing partner in many collaborations sponsored by international organizations. Past collaborations, such as the 1997 joint Organization for Economic Cooperation and Development (OECD)/Nuclear Energy Agency (NEA) and the International Atomic Energy Agency (IAEA) International Peer Review of the 1996 WIPP performance assessment, and ongoing collaborations such as the Performance Assessment Advisory Group (PAAG) and the Integrated Performance Assessment Group (IPAG), have had a strong, positive impact on the credibility of the CAO's experimental programs and interpretations as well as on systems-level modeling. The CAO is also currently involved in the OECD/NEA forum on sorption modeling in performance assessment, the OECD/NEA Site Evaluation and Design of Experiments (SEDE) group, and the OECD/NEA Geological Transport of Radionuclides Predictions (GEOTRAP) Forum. The CAO anticipates continued collaboration in current and new activities that may be sponsored by a variety of organizations, such as the IAEA, the OECD/NEA, and the European Commission. (EC).
CAO PROGRAMS OF POTENTIAL INTEREST TO THE
INTERNATIONAL COMMUNITY
There are many technical disciplines in which the CAO and other organizations/projects have similar interests and where the CAO has acquired considerable knowledge that could be of value to other programs. The similarity is based on recognition that all sites proposed for geologic disposal must be characterized for basic geologic, geochemical, hydrologic, and construction feasibility properties. All sites intend to use shaft seals and/or engineered barriers. Most sites are evaluated in the context of formal risk assessment or performance assessment. The CAO international research and development (R&D) program provides convenient access to the considerable knowledge CAO has assembled in these topical areas:
The CAO welcomes proposals for information exchange or new mutually beneficial collaborative efforts.
Specific Capabilities of Potential Interest to the International Community
Through its scientific advisor, Sandia National Laboratories, the CAO has access to several specific technical capabilities in specialized facilities that may be of interest to the international community. These facilities include:
The CAO welcomes proposals for collaborative investigations that may utilize these special capabilities.
SUMMARY
The CAO has established an IR&D program to achieve its mission to open and operate the WIPP repository for safe disposal of TRU waste and to cost-effectively integrate the NTP. The objective of the IR&D program is to stimulate mutually beneficial collaborations between the CAO and other radioactive waste management programs and organizations. The CAO desires continued and new international collaboration and partnerships in a variety of programmatic areas where such collaboration will provide mutually beneficial enhancement of public confidence, and scientific and operational improvements which may lead to enhanced demonstration of system safety and cost savings. Types of collaboration may include, for example, experimental or technology development and/or demonstration partnerships or primarily information exchange. A continuing important part of the overall R&D program is participation on committees and in forums hosted by international organizations such as the OECD/NEA, the IAEA, and the EC. To facilitate accelerated information exchange in those areas where CAO is making significant contributions to the state of knowledge (for example, backfill use and multi-rate transport of radionuclides in fractured geologic media), the CAO will sponsor technical workshops targeted to the common needs of the U.S. and the international nuclear waste management community.
FURTHER READING ON WIPP
National Academy of Sciences' Committee on the Waste Isolation Pilot Plan. 1996. The Waste Isolation Pilot Plant: A potential Solution for the Disposal of Transuranic Waste. Washington, D.C.: National Academy Press.
Organization for Economic Co-operation and Development and the International Atomic Energy Agency. 1997. OECD/NEA - IAEA Joint International Review of Waste Isolation Pilot Plant 1996 Performance Assessment.
Public Law 102-579. 1992. The Waste Isolation Pilot Plant Land Withdrawal Act of 1992.
Public Law 104-201. 1996. Amendments to the LWA.
U.S. DOE (Department of Energy). 1997. Carlsbad Area Office Disposal Phase Experimental Program Plan. DOE/CAO 97-1223, Rev. 0. Carlsbad, NM: USDOE.
U.S. DOE (Department of Energy). 1997. Carlsbad Area Office International Research and Development Plan. DOE/CAO 97-1266, Rev. 0. Carlsbad, NM: USDOE.
U.S. EPA (Environmental Protection Agency). 1993. 40 CFR Part 191: Environmental Radiation Protection Standards for the Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes: Final Rule; Federal Register, Vol. 58, No. 242, pp. 66398-66416, December 20, 1993. Office of Radiation and Air. Washington, D.C.: USEPA.
U.S. EPA (Environmental Protection Agency). 1996. Criteria for the Certification and Recertification of the Waste Isolation Pilot Plant's Compliance With the 40 CFR Part 191 Disposal Regulations: Final Rule; Federal Register, Vol. 61, No. 28, pp. 5224-5245, February 9, 1996. Office of Radiation and Indoor Air. Washington, D.C.: USEPA.