Drift Scale Test

Task 2 The Drift Scale Test (DST) in the Exploratory Studies Facility (ESF) at Yucca Mountain, USA... 

MEASURING THERMAL, HYDROLOGICAL, MECHANICAL, AND CHEMICAL RESPONSES IN THE YUCCA MOUNTAIN DRIFT SCALE TEST... 

As shown in Figures 1, a large number of bore holes are drilled from the drifts into the test block to house the heaters, instruments, and sensors. Approximately 3500 sensors of various types are installed in some 3300 meters of bore holes and elsewhere. At the end of four years of heating in January 2002 the volume of rock heated to above 100 C exceeded 20,000 cubic meters. The DST is described in detail in Drift Scale Test Design and Forecast Results (CRWMS M O, 1997). 

CRWMS M O, 1997. Drift Scale Test Design and Forecast Results. Report BABOOOOOO-01717-4600-(KX)07, Rev.Ol, prepared by the Civilian Radioactive Waste Management System Management and Operating Contractor for the U.S. Department of Energy Yucca Mountain Site Characterisation Office, Las Vegas, Nevada, December 1997. 

Millard, A. and J. Rutqvist, 2003. Comparative Analyses of Predicted and Measured Displacements During the Heating Phase of the Yucca Mountain Drift Scale Test. Proceedings (to be published). GeoProc2003, Stockholm, Sweden, October 2003. 

Figure I. Three-dimensional view of the Yucca Mountain Drift Scale Test...

Millard, A. Rutqvist, I. 2003. A comparative analysis of predicted and measured displacements during the heating phase of the yucca mountain drift scale test. Geoproc Conf., Stockholm, Sweden. 

The host rocks for the proposed repository at Yucca Mountain include Topopah Spring Upper Lithophysal (Tptpul), Topopah Spring Middle Nonlithophysal (Tptpmn), Topopah Spring Lower Lithophysal (Tptpll), and Topopah Spring Lower Nonlithophysal (Tptpln) units. The drift-scale heater test facility is located in the Tptpmn unit (CRWMS M O, 1997). The Tptpmn unit is 30-40 m thick at the location of the drift-scale test area. This unit is overlain by the Tptpul and underlain by the Tptpll units. The heater drift is approximately 5 m in diameter and 47.5 m long, and its entrance is closed by a thermal bulkhead. 

CRWMS M O. 1997. Ambient Characterization of the Drift-Scale Test Block. BADDOOOOO-01717-5705-00001. Rev. 01. Las Vegas, Nevada CRWMS M O. 

The in situ DST (Drift Scale Test) consist in a 47.5 m long, 5 m diameter drift heated by 9 heaters simulating waste canisters placed on the floor. Additional heat is supplied by 50 wing heaters inserted into horizontal boreholes drilled into each side wall (Datta, 2002). 

Ambient Characterization of the Drift Scale Test Block, 1977, TRW Environmental Safety Systems Inc. 

Datta, R.N. DECOVALEX m PROJECT, Task 2A, Interim Report (Revised). Thermal-Hydrological Predictive Simulation of the Yucca Mountain Project Drift Scale Test, February 2002. 

Abstract As a part of the DECOVALEX 111 project—model predictions were carried out of thermomechanical (TM) rock-mass responses at the Yucca Mountain drift scale test (DST), Nevada. This paper presents model predictions of TM-induced rock displacements at the DST carried out by two independent research teams using two different approaches and two different numerical models. Displacements predicted by the two independent analyses compare reasonably well to the measured ones, both in trends and average magnitude. The analyses indicate that the rock mass behaviour is essentially elastic and that the in situ rock mass thermal expansion coefficient is well represented a temperature-dependent thermal-expansion derived from laboratory tests on intact rock. 

Dana R., Barr, D, Boyle, W., Jing, L. 2003. Measuring the thermal, hydrologic, mechanical and chemical responses of the Yucca Mountain Drift Scale Test. Geoproc Conf, Stockholm, Sweden... 

The long-term performance of the repository at Yucca Mountain will be affected by the coupling of thermal, hydrological and chemical (THC) processes in the rock around the emplacement drifts. The transport of heat, fluid, and vapor will result in changes in water and gas chemistry, as well as mineral dissolution and precipitation which may lead to permanent changes in porosity, permeability and unsaturated hydrological properties. The purpose of this contribution is to describe the approach used to model reaction-transport processes in the Drift Scale Test (DST) with comparisons of simulation results to measured geochemical data on water, gas, and minerals. 

Birkholzer, J, T. Tsang, Y. W. 1998. Interpretive Analysis of the Thermo-Hydrological Processes of the Drift Scale Test. In Drift Scale Test Progress Report, Chapter 6. Yucca Mountain Project Level 4 Milestone SP2930M4. Berkeley, California Lawrence Berkeley National Laboratory. 

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