Preparation for YMP backfill activities
Yucca Mountain activities for FY 1999 are anticipated to require specific information on the chemical and physical properties of the candidate getter materials and other backfill components necessary for defensible modeling of the source term, and possible controlling of the source term. There should be three tasks to this activity: at the end of this report is a draft test plan reflecting the present funding anticipated, the other tasks may be added as funding becomes available. (Task 1) The immobilization capacity of the getter materials for specific radionuclides. This task will primarily include column sorption tests of getter materials with solutions spiked with radionuclides. The getter materials will include Apatite II, MgO (with NaPO{sub 4} plus Ba,SrCO{sub 3} and soluble sulfate, with and without Apatite II), Gibbsite/Boehmite, and Hematite. Radionuclides will include Pu, U, Np, Am, Ra, Tc, and Th. Experiments will be performed under various anticipated repository conditions and with anticipated solution compositions. Occasional batch tests will be used to obtain specific K{sub d}s and other thermodynamic data. Solid and liquid analyses will be needed for characterization of the effluent concentrations from the columns to assess performance and for use in geochemical modeling. (Task 2) Intrinsic stability of the getter materials under repository conditions. The use of any candidate getter material will depend upon its anticipated lifetime in the backfill environment. Literature search for any existing data will be performed and augmented by solubility experiments on the getter materials. This is especially important for the reactive materials such as MgO and the soluble sulfates and phosphates that may be a limited lifetime in the backfill. It is also necessary to decide how much getter material to emplace. (Task 3) Diffusion of radionuclides across a Richards Barrier. The Richards Barrier, if emplaced, will act as a hydraulic diversion barrier for the diversion of water around the waste package, and sand and gravel may be used beneath the packages for various reasons. It has been postulated that these materials will also act as diffusion barriers to radionuclide migration across them, especially under unsaturated conditions. Macroscale experiments in LANL's hot facility will be used to measure radionuclide migration across the interface of these barriers which will be constructed using crushed YM tuff and Overton Sand from Nevada. Tritium will be used as a conservative tracer. These experiments will provide the data necessary to evaluate the retardation properties of the backfill materials and to determine whether precipitation or adsorption dominates in each material, and whether the repository environment is favorable for its performance. The scope of work may change as information develops from this activity and from other activities, as close interactions will occur between these activities. In anticipation of these activities, the authors are performing several calculations and experiments. First, they are compiling information on the properties of the candidate backfill and invert materials for use in decision-making, for modeling purposes and for identifying data gaps. Table 1 provides the first draft of information on the possible backfill materials and Table 2 provides information on the possible invert materials.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 758822
- Report Number(s):
- LA-SUB-99-5; LANL-Subcontract-No.215BA0016-3Y; LANL Subcontract No. 215BA0016-3Y; TRN: US0004123
- Resource Relation:
- Other Information: Subcontract Report, UFA Ventures, Inc.; PBD: 23 Dec 1998
- Country of Publication:
- United States
- Language:
- English
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