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Analysis of transient history of underground excavations for radioactive waste isolation

Description: The constraints and phenomena which must be modeled in realizing a rational prediction of temperature history in a radioactive waste repository are presented. The effects of conductive and radiative heat transfer between the waste package and host rock are presented. Results of numerical investigations are utilized to present specific situations wherein analytical approximations to the waste canister geometry may be utilized. The paper also presents the results of approximations to the mean underground repository temperatures. The reliability of both methods of predicting temperatures is assessed through the comparison of predicted temperatures with measured temperatures from the Project Salt Vault field experiment. The design of experiments for model verification is discussed and a specific heater experiment which has been proposed is presented.
Date: August 1, 1977
Creator: Ratigan, J. & Van Sambeek, L.
Partner: UNT Libraries Government Documents Department

Simulation of the thermomechanical response of Project Salt Vault. Final report

Description: The feasibility of economically and accurately applying Lagrangian explicit finite-difference (EFD) techniques to the analysis of the thermomechanical response of radioactive wastes placed in salt repositories is demonstrated. Three numerical simulations of the Project Salt Vault (PSV) experiment were carried out, using STEALTH 2D, a two-dimensional EFD code. One calculation did not include a model for creep, while the other two calculations used a general model in which creep was included. As expected, when creep was included, it resulted in significantly more pillar shortening and room convergence than when it was not included. The first of the creep simulations (as well as the non-creep simulation) was designed to demonstrate the applicability of the EFD method.The second creep simulation was performed to evaluate the sensitivity of certain numerical parameters, such as zone size and boundary nearness. Numerical data are presented that compare the results of the three simulations to the results of the Project Salt Vault experiment. In the simulations which included creep, the room closure data are in excellent agreement with the shape and magnitude of the experimentally measured floor and roof closures. Temperature histories were also compared at several locations and these data were also in agreement with the experimental values.
Date: February 1, 1977
Creator: Wahi, K.K.; Maxwell, D.E. & Hofmann, R.
Partner: UNT Libraries Government Documents Department

Review of proposed formats for safety analysis reports for radioactive waste repositories in deep geologic formations. Final report

Description: Two proposed Safety Analysis Report format outlines for submission to the Nuclear Regulatory Commission for approval of federal repositories for terminal storage of radioactive wastes were reviewed and comments developed in light of past nuclear licensing experiences and current Regulatory Guides. It was concluded that an SAR format and content guide can be developed within the fundamental framework of Regulatory Guide 3.26 by the incorporation of some additional salient features. Further revision and/or development are needed for ''Site Characteristics,'' ''Facility Description,'' and ''Process Systems.'' Close coordination of the parallel activities contained in the proposed SAR development schedule will be required. Two additional SAR support effects are recommended. (JSR)
Date: September 1, 1977
Partner: UNT Libraries Government Documents Department

Two-dimensional simulation of the thermomechanical response of project salt vault including the excavation sequence. Final report

Description: Based on comparisons of the present four-room sequential excavation calculational results with previous two-room simultaneous excavation results and the experimental results, the following may be concluded: (1) The sequence of excavation plays no role in overall deformation response of rooms and pillars, provided that sufficient time (approx. 6 months) lapse exists between the last excavation and the start of the heat source. (2) The assumption of a symmetry plane between Rooms 2 and 3 is valid in modeling the Project Salt Vault experiment. (3) In a realistic simulation, one should allow the creep deformations to occur on real time scale even during the period when no thermal source is active (e.g., between standard day 540 and standard day 806). In particular, reference is made to the two-room sensitivity calculation which was started at standard day 806. In that calculation the creep stain rates at day 806, and cumulative strains until day 806 were erroneous. However, the overall thermomechanical response was still in fairly good agreement with the experimental data. 7 figures.
Date: March 1, 1978
Creator: Wahi, H.K.; Maxwell, D.E. & Hofmann, R.
Partner: UNT Libraries Government Documents Department

Asse salt mine nuclear waste repository simulation experiments

Description: The field tests underway in Asse, Federal Republic of Germany are dicected toward the development of test plans, techniques and equipment to be used in Exploratory Shafts or At Depth Test Facilities confirmation tests. These simulated repository tests will also provide information which address the following issues: brine migration (liquid and vapor); radiation effects of gamma rays; gas generation caused by radiation and corrosion; accelerated corrosion and leaching; altered properties of salt (the effects of heat, radiation and brine); and the effects of heat and radiation on test assemblies, instruments, and various materials exposed to repository conditions. This paper is a status of the first 82 days of operation of the Asse Brine Migration Tests, which were initiated on May 25, 1983. 6 references.
Date: January 1, 1983
Creator: Coyle, A.J.
Partner: UNT Libraries Government Documents Department

Geologic mapping of the air intake shaft at the Waste Isolation Pilot Plant

Description: The air intake shaft (AS) was geologically mapped from the surface to the Waste Isolation Pilot Plant (WIPP) facility horizon. The entire shaft section including the Mescalero Caliche, Gatuna Formation, Santa Rosa Formation, Dewey Lake Redbeds, Rustler Formation, and Salado Formation was geologically described. The air intake shaft (AS) at the Waste Isolation Pilot Plant (WIPP) site was constructed to provide a pathway for fresh air into the underground repository and maintain the desired pressure balances for proper underground ventilation. It was up-reamed to minimize construction-related damage to the wall rock. The upper portion of the shaft was lined with slip-formed concrete, while the lower part of the shaft, from approximately 903 ft below top of concrete at the surface, was unlined. As part of WIPP site characterization activities, the AS was geologically mapped. The shaft construction method, up-reaming, created a nearly ideal surface for geologic description. Small-scale textures usually best seen on slabbed core were easily distinguished on the shaft wall, while larger scale textures not generally revealed in core were well displayed. During the mapping, newly recognized textures were interpreted in order to refine depositional and post-depositional models of the units mapped. The objectives of the geologic mapping were to: (1) provide confirmation and documentation of strata overlying the WIPP facility horizon; (2) provide detailed information of the geologic conditions in strata critical to repository sealing and operations; (3) provide technical basis for field adjustments and modification of key and aquifer seal design, based upon the observed geology; (4) provide geological data for the selection of instrument borehole locations; (5) and characterize the geology at geomechanical instrument locations to assist in data interpretation. 40 refs., 27 figs., 1 tab.
Date: December 1, 1990
Creator: Holt, R.M. & Powers, D.W. (IT Corporation (USA))
Partner: UNT Libraries Government Documents Department