Thermohydromechanical simulations of the natural cooling stage of the Tunnel Sealing Experiment

The Tunnel Sealing Experiment (TSX), located on the 420 Level of the Underground Research Laboratory (URL) of Atomic Energy of Canada Limited (AECL), was used to study the behaviour of two bulkheads installed in situ: one composed of highly compacted bentonite-sand blocks, the other composed of low-heat high-performance concrete. Permeable sand was placed in an 11.2-m-long chamber between the bulkheads. The chamber was first pressurized with water to 4 MPa to simulate the conditions likely to develop in the period following installation of seals in an actual repository. A stage of circulating hot water in the chamber began on 2002 September 24. The maximum design temperature of 85 °C at the interior face of the bulkheads could not be achieved in the time available. The actual maximum temperature was 65 °C. The purpose of heating was to investigate the thermohydromechanical responses in the bulkheads and surrounding rock to increased temperature. A passive cooling stage followed the heating stage. To help understand the influence of natural cooling on the thermohydromechanical response, a series of coupled thermohydromechanical modelling exercises was carried out using the finite element program, Model Of Transport In Fractured/porous media (MOTIF), and the results were compared with measured data. The thermal response in the rock and the bulkheads was successfully simulated. The influence of hydraulic conductivity on the hydraulic response in the clay bulkhead was analyzed.     

A study of the compaction properties of potential clay—sand buffer mixtures for use in nuclear fuel waste disposal

In-situ emplacement of clay-based buffers in a nuclear fuel waste disposal vault limits the maximum attainable buffer density. This will vary with the composition of the buffer. A study of the maximum attainable densities of candidate Na bentonite/sand and illite/sand buffers is described. The addition of sand significantly increases the achievable compacted density. This increase may be obtained without any decrease in the swelling pressures developed by Na bentonite buffers. Sand decreases the shrinkage potential of the buffer and may also decrease the mass diffusion coefficient. A mixture of 50% sand and 50% clay by mass appears to optimise the physical properties of the buffer.     

A modest all-sky search for narrowband radio radiation near the 21-cm hydrogen line

Since 1973 an all-sky, full-time search for narrowband radio radiation (presumably of intelligent origin) near 21 cm has been underway at the Ohio State University Radio Observatory. The search concentrates on a band 380 kHz wide centered on the hydrogen line, corrected to the Galactic Standard of Rest. The search is limited by lack of funding and personnel. It has been found that beam switching is an important technique for reducing terrestrial interference, and that galactic hydrogen emission does not cause significant extraterrestrial interference. A number of small-diameter cold hydrogen clouds have been discovered. No confirmed narrowband extraterrestrial signals have been found between +48° and +14° in declination above the detection limit of 1.5 × 10^?21 W/m².     

Near–surface ground temperature regime variability in selected microenvironments, Kärkevagge, Swedish Lapland

The importance of topographic microvariability in influencing shallow (10–50 cm depths) soil temperature regimes in arctic–alpine Kärkevagge, northern Sweden, from August 1999 to July 2000 is demonstrated using six sites. The ground microclimate on the tops of very large boulders forming an extensive boulder field in the central valley bottom is more comparable to that at an alpine ridge–crest site 300 m higher than it is to the microclimate at the base of one of the boulders. The boulder crests also differ substantially from the more generalized valley–bottom conditions outside the boulder field. Assuming that chemical processes may be active at temperatures at or above 0°C, sites in the valley experience favorable conditions from 159 to 324 days of the year. Aside from the annual cycle, freeze–thaw cycles are infrequent within Kärkevagge.     

Near–surface ground temperature regime variability in selected microenvironments, Kärkevagge, Swedish Lapland

The importance of topographic microvariability in influencing shallow (10–50 cm depths) soil temperature regimes in arctic–alpine Kärkevagge, northern Sweden, from August 1999 to July 2000 is demonstrated using six sites. The ground microclimate on the tops of very large boulders forming an extensive boulder field in the central valley bottom is more comparable to that at an alpine ridge–crest site 300 m higher than it is to the microclimate at the base of one of the boulders. The boulder crests also differ substantially from the more generalized valley–bottom conditions outside the boulder field. Assuming that chemical processes may be active at temperatures at or above 0°C, sites in the valley experience favorable conditions from 159 to 324 days of the year. Aside from the annual cycle, freeze–thaw cycles are infrequent within Kärkevagge.     

The Use of Close Range Photogrammetry for Studying Ice Accretion on Aerofoil Sections

This paper describes the use of photogrammetry to measure and quantify ice accretion on an aerofoil section. A series of stereoscopic photographs was taken during the ice accretion on the section in an icing tunnel. From measurements made on these photographs with a Kern (Leica) DSR 14 analytical photogrammetric plotter, a series of three dimensional models of the ice surfaces was constructed. The results of the project are discussed and possible improvements in the methodology are suggested.