This report presents a review of sensors and technologies that are capable of detecting and monitoring volatile organic compounds. The scope of this review was limited to those sensors that have the potential to be used in geologic environments for long-term monitoring applications. Four general categories of sensor technologies were reviewed: (1) chromatography and spectrometry; (2) electrochemical sensors; (3) mass sensors; and (4) optical sensors. Based on the review criteria set forth in this report, the most viable sensors for in-situ chemical sensing appear to be electrochemical sensors (specifically conductometric sensors), fiber-optic sensors, and surface-acoustic-wave sensors. However, very few chemical sensors have been successfully demonstrated in realtime, continuous, in-situ applications.iv Acknowledgments

The FEBEX (Full-scale Engineered Barriers Experiment in Crystalline Host Rock) ''in situ'' test was installed at the Grimsel Test Site underground laboratory (Switzerland) and is a near-to-real scale simulation of the Spanish reference concept of deep geological storage in crystalline host rock. A modelling exercise, aimed at predicting field behaviour, was divided in three parts. In Part A, predictions for both the total water inflow to the tunnel as well as the water pressure changes induced by the boring of the tunnel were required. In Part B, predictions for local field variables, such as temperature, relative humidity, stresses and displacements at selected points in the bentonite barrier, and global variables, such as the total input power to the heaters were required. In Part C, predictions for temperature, stresses, water pressures and displacements in selected points of the host rock were required. Ten Modelling Teams from Europe, North America and Japan were involved in the analysis of the test. Differences among approaches may be found in the constitutive models used, in the simplifications made to the balance equations and in the geometric symmetries considered. Several aspects are addressed in the paper: the basic THM physical phenomena which dominate the test response are ARTICLE IN PRESS www.elsevier.com/locate/ijrmms 1365-1609/$ -see front matter r

--The objective of this heat transfer and fluid flow study is to assess the ability of a computational fluid dynamics (CFD) code to reproduce the experimental results, numerical simulation results, and heat transfer correlation equations developed in the literature for natural convection heat transfer within the annulus of horizontal concentric cylinders. In the literature, a variety of heat transfer expressions have been developed to compute average equivalent thermal conductivities. However, the expressions have been primarily developed for very small inner and outer cylinder radii and gap-widths. In this comparative study, interest is primarily focused on large gap widths (on the order of half meter or greater) and large radius ratios. From the steady-state CFD analysis it is found that the concentric cylinder models for the larger geometries compare favorably to the results of the Kuehn and Goldstein correlations in the Rayleigh number range of about 1 O5 to 10' (a range that encompasses the laminar to turbulent transition). For Rayleigh numbers greater than 1 Os, both numerical simulations and experimental data (from the literature) are consistent and result in slightly lower equivalent thermal conductivities than those obtained from the Kuehn and Goldstein correlations.

Natural convection heat and mass transfer under post-closure conditions has been calculated for Yucca Mountain drifts using the computational fluid dynamics (CFD) code FLUENT. Calculations have been performed for 300, 1000, 3000, and 10,000 years after repository closure. Effective dispersion coefficients that can be used to calculate mass transfer in the drift have been evaluated as a function of time and boundary temperature tilt.

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