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The effects of temperature, purity, magnetic state, and crystal structure on the thermal conductivity, electrical resistivity, and Seebeck coefficient of iron were obtained from measurements on Armco iron (99.5% pure, ρ300/ρ4.2=11.0) and a high-purity iron (99.95% pure, ρ300/ρ4.2=26.2). The most probable determinate errors of the measurements were thermal conductivity ±1.5%, electrical resistivity ±0.1%, and Seebeck coefficient ±0.9%; and larger absolute errors. Where theory permits, the thermophysical properties of iron are discussed in terms of contributing transport mechanisms. The thermal conductivity of iron can be calculated to ±1.5% between 0° and 910°C from electrical-resistivity measurements and the lattice portion of the thermal conductivity determined in this study.

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The thermal conductivities, h, of single-crystal and polycrystalline UO, were measured from 80" to 420°K. The results indicate no observable difference in h between single-crystal and polycrystalline UO,, and both materials have broad peaks in x a t ~2 2 0°K . The results were used with literature values to determine the effect of closed porosity on A. The thermal conductivity of theoretically dense UO, is described phenomenologically from 80" to 140O0K, where conduction is dominated by the phonon component. The phonon conduction is analyzed by comparison with Tho,. This analysis indicates that the high-temperature x is limited by 3-phonon Umklapp scattering processes. Scattering by the disordered spins associated with the paramagnetic U ions contributes a large temperatureindependent phonon scattering term. This mechanism has a mean free path of about 51 A, which implies that grain boundaries and impurities have a relatively insignificant effect on the phonon conduction far above the antiferromagnetic-paramagnetic transition a t -30°K. This implication agrees with the experimental results.

This paper reports apparent thermal conductivity (k) values from field and laboratory aging tests on a set of industry-produced, experimental polyisocyanurate (PIR) laminated boardstock foamed with hydrochlorofluorocarbons (HCFCs) as alternatives to chlorofluorocarbons (CFCs). The PIR boards were blown with five gases: CFC-11, HCFC-123, HCFC-141b, and 50/50 and 65/35 blends of HCFC-123/ HCFC-141b. The k-values were determined at mean temperatures from 0 to 50°C (30 to 120°F) using techniques that meet ASTM C 1114 (Thin Heater Apparatus) and ASTM C 518 (Heat Flow Meter Apparatus) test methods. Results on laminate boards with facers provide an independent laboratory check on the increase in k observed for field exposure in the ORNL Roof Thermal Research Apparatus (RTRA). The observed laboratory increase in k was between 8% and 11% for all three blowing agent foams for a 240 day field exposure in the RTRA. A thin-specimen aging procedure established the long-term thermal resistance of gas-filled foams. Thin specimens were planed from the industry-produced boardstock foams and aged at 24 and 65°C for up to 300 days. An exponential dependency of k with the quantity (diffusion coefficient X time)½/thickness, provided effective diffusion coefficients for air components into the foams and blowing agent out of the foams. The foams blown with alternative blowing agents exhibited k-values 8 to 16% (average 12.7%) above CFC-11 foams under similar conditions. Field exposures were conducted on specimens under single ply EPDM membranes in the RTRA for over 400 days. Hourly averages of panel temperature and heat flux were analyzed to obtain k as a function of mean temperature on a week by week basis. The k-values derived from the field data provided effective diffusion coefficients for air components in the foam, which were greater than those obtained from the thin-specimen aging procedure at 24°C by 20 to 70%, but were less than the 65°C aging values by 20 to 80%. The relative performance of test specimens of HCFC-141b under a black and under a white membrane is reported. The field data suggests that the percent increase in k over that of the foam blown with CFC-11 is, after one year of aging, 4.3% for HCFC-123 and 10.2% for HCFC-141b. This leads to the same ordering of foams as derived from the thin-specimen analysis.

The detection of moisture movement in the vadose zone beneath hazardous waste disposal sites is important for monitoring and predicting contaminant transport in the subsurface. This study was conducted to determine if moisture movement could be detected from natural water infiltration in a dual porosity, fractured basalt at the Idaho National Engineering and Environmental Laboratory (INEEL). Episodic infiltration events were determined by examining long-term water potential over three and a half years. Water potential measurements were collected from 2 to over 30 m below land surface. Instruments were placed in both fractured and unfractured basalt media. Water potential measurements were within the tensiometric range, from approximately +100 to −250 cm of water. Typically, water potentials within the fractured basalt exhibited a near steady-state unit-gradient downward flux. However, episodic snowmelt infiltration events at land surface produced detectable changes in water potentials at depths to 15.5 m, in some cases within a few days of the infiltration events. Smaller infiltration events were difficult to distinguish due to fluctuations in water potential resulting from changes in barometric pressure. Water potential responses in boreholes varied both temporally and spatially during episodic infiltration events indicating preferential flow pathways through the fractured basalt. The results of this study indicate that water potential measurements can be used to detect and monitor deep infiltration events at waste disposal sites using tensiometers.

This paper analyzes transient radiation and conduction heat transfer through planar porous materials. The transient response considered is caused by a sudden increase of heat generation at the hot boundary. The objective was to establish the effect of radiation on the temperature rise of the hot wall. The problem investigated is relevant to the use of transient methods for measuring the thermal conductivity of porous insulations. It was found that, in cases such as when the porous material is a light-weight fiberglass insulation, neglecting radiation would result in serious errors in predicting the hot wall temperature rise.

A radial heat flow technique was used to measure the thermal conductivity, k, of polycrystalline UO2in the range ‐57° to 1100°C. The technique yielded results with a probable accuracy of ±1.5% and a precision of ±0.1% in the range 50° to 1100°C. Meaningful measurements were limited to 1100°C by Pt‐90 Pt10Rh thermocouple instability, although the apparatus was structurally sound to 1400°C. The thermal conductivity data up to 1000°C could be explained on the basis of heat transport by phonons. The thermal resistance, l/k, exhibits a linear temperature dependence from 200° to 100°C, which is expected for an insulator well above the Debye temperature. The slope of the l/k‐temperature plot is 0.0223 cm w−1 which is independent of impurity content and is associated with three phonon umklapp processes. The intercept is sensitive to impurity content as indicated by the fact that it was decreased by a decrease in the oxygen/uranium ratio. Between 1000° and 1100°C, there is a slight departure of l/k from linearity which may be due to the onset of an electronic contribution. Near room temperature, UO2 has a maximum in k which is apparently caused by the rapid decrease in specific heat below this temperature.