Radioactive waste management policies in seven industrialized democracies*

This paper provides an inventory of radioactive waste management policies in seven industrialized democracies: the U.S., France, Japan, West Germany, Canada, the U.K. and Sweden. Collectively, these countries account for almost 75% of the world's installed nuclear power capacity and over 61% of its spentfuel production. Special emphasis is given to siting procedures for both high- and low-/intermediate-level waste repositories. Although several low-level repositories are operating or under construction, only West Germany has selected a site for high-level waste disposal, at Gorleben. It is expected that siting decisions will be highly conflict-laden in each country except for pro-nuclear France. The procedures for resolving potential siting conflicts are briefly reviewed. Sweden's strategy of siting its low-level repository near Forsmark offshore beneath the Baltic seabed minimizes conflict and may become attractive to other nations. Also, transnational agreements may eventually be sought as radioactive waste disposal is an international problem. This paper concludes with a comparative discussion of siting policies and their potential impacts.     

Limitations of ‘Rock-Eval’ pyrolysis for typing organic matter

Laboratory experimentation on whole-rock ‘Rock-Eval’ pyrolysis has shown that the characterization of organic matter through the use of a modified van Krevelen diagram, in which the hydrogen and oxygen indices are substituted for the atomic H/C and O/C ratios, produces questionable results. The hydrogen and oxygen indices have been found to be strongly affected by both matrix mineralogy and level of organic enrichment. It appears, therefore, that although the modified van Krevelen diagram maybe useful for tracing evolutionary pathways as organic matter matures, it can be very misleading when used to assess kerogen type.     

Geothermal and other effects on amino acid racemization in selected Deep-Sea Drilling Project cores

Kinetic parameters for the epimerization of isoleucine in multispecific foraminiferal asemblages were used to establish the effects of burial depth and the geothermal gradient on the extent of reaction. It was observed that with a little as thirty meters of burial in a normal thermal regime there were differences between the extent of epimerization measured and that which would have been predicted for thermal equilibrium with bottom water temperatures. As would be expected, these differences are greatest when the heat flow (the geothermal gradient) and/or the sedimentation rates are highest. These effects were observed in most of the DSDP samples studied, and have been used to estimate the average heat flux since the time of sample deposition. Occasional anomalous effects were observed which could not be related to past or present heat flux. These were determined to be due to such geologic occurrences as slumping and reworking or to recent sample contamination. Other problems emerged related to bottom water temperatures including changes over geologic time which are unknown and could not be deduced. Thus, the presence of epimerization anomalies in DSDP cores as noted above limits the effectiveness of amino acid geochronology in such cores, unless these anomalies can be recognized as ab initio.     

Cladding influence on dynamics response of tall buildings

Precast concrete panels form attractive facades for steel frame buildings and are generally regarded as non-structural by structural engineers. However, panels have been found to add lateral stiffness until their capacity or that of their connections is exceeded. Consequently, the computed dynamic response based on a model of the structural framing alone may be quite different from that experienced by the actual structure. As a case study, the influence of precast concrete panels on lateral and torsional stiffness of a 25-storey building was investigated. The effect of cladding on dynamic properties and linear seismic response was explored by varying panel stiffness. Cladding stiffness was added to the bare frame model until analytical frequency values matched vibration test results. Then, using the cladding stiffness values obtained, an accidental eccentricity between centres of mass and rigidity at each floor level was imposed and linear seismic response computed. Torsional response effects were increased substantially. Finally, a modified cladding panel connection was developed based on previously-reported studies for panelized construction. The influence of the proposed connection on overall structural response was determined for different ground motion inputs.     

A comparison of cloud motion and ship wind observations over the Indian Ocean for the year of FGGE

Cloud motions over the Indian Ocean were compared to ship observations for the FGGE year. The statistics of this comparison show seasonal changes in the cloud-ship relationship as well as geographical and wind-pattern-dependent fetch history changes. Most of these changes follow simple boundary-layer relationships governed by friction and temperature advection. The most significant result is the improvement of the cloud-ship directional shear with wind speed. The mean veering angle between cloud and ship measurements decreased at higher wind speeds along with scatter of the shearing angle. This implies that the ability of cloud motion measurements to indicate the wind stress on the ocean improves for the important situations when the winds are strong.     

Frost action and hydration as rock weathering mechanisms on schist: A laboratory study

Recently it has been proposed that stress generated by the adsorption of water to clay surfaces in argillaceous rocks may be an important agent of mechanical weathering in polar and alpine environments, implying that long-held views on the status of frost action in these areas may be in need of revision. This study documents the response, under controlled experimental conditions, of aggregates of fresh and partlyweathered schist and fresh pre-cut schist blocks to 500 accelerated (12 hour) freeze-thaw and hydration-dehydration cycles. Aggregate samples subjected to freezing cycles produced the largest amounts of material in the less than 2 mm size range (an average of 8 per cent and 16 per cent for the fresh and partly-weathered aggregates respectively), whereas humidity cycles above and below freezing yielded lesser amounts (3 per cent and 4 per cent respectively). The fresh schist blocks were found to be highly resistant to both mechanisms; only those experiencing freeze-thaw oscillations produced measurable amounts of detritus. Although hydration effects were not as effective as frost action in causing particle size reduction in aggregates, the two mechanisms may well reinforce one another in periglacial environments, enhancing the ability of these areas to serve as source regions for loess.     

Fracture analysis near the mid-ocean plate boundary, Reykjavik-Hvalfjördur area, Iceland

The geometry and thermal history of fractures have been determined at 59 stations from Reykjavik to Hvalfjördur in southwestern Iceland. The data provide information on crustal stress regimes in the vicinity of mid-ocean ridges.Two major, generalized fracture orientations are present

1. (1) a northeast system, trend 010°–030°, except on Akranes where the orientation is 040°–060°

2. (2) a broad east—west system containing one or more sets with strike between 070°–130°.

Thermal history of the host rock and fractures was determined from secondary minerals in vugs and fractures. The thermal history indicates that the northeast fracture set opened while the area was within the relatively hot axial zone of active volcanism and rifting. Some of the east—west trending fractures also opened at this time but many formed later, after the area had begun to cool and drift from the active zone.The northeast fracture set is essentially parallel to the trend of dikes and normal faults in southwestern Iceland. They have been interpreted as extension fractures (resulting in about 0.4% maximum extension) forming generally from the same stress field associated with normal faulting and dike injection in the active zone. Fracturing in an east-west direction (estimated 0.1% maximum extension), mainly near the edge and outside the active zone, indicates a reorientation of this stress field. The dominant mechanism related to the origin of the east—west fractures may be thermoelastic stresses arising from axial and basal accretion and cooling of lithospheric plates.Both fracture systems are inferred to have formed, in the Griffiths idealization, under nearly biaxial effective compressive loading on the order of 200 bar. The discrepancy between this value and the kilobar-order strengths of short-time laboratory tests reflects such factors as high temperature stress corrosion and fatigue. Fracture propagation is assumed to have been stable, but governed primarily by lateral load-diminishing mechanisms rather than by progressive loading. These relaxation mechanisms may have been episodic (northeast-system fissure swarm activity) or steady-state (thermoelastic contraction) in time.     

Lewisian gneiss geochemistry and Archaean crustal development models

The geochemistry of Lewisian amphibolite-facies gneisses from northwest Scotland is described with particular reference to the rare earth elements (REE) and compared with the geochemistry of Lewisian granulite-facies gneisses. The results show that there are no significant differences between “Laxfordian” amphibolite-facies and “Scourian” granulite-facies gneisses in terms of REE and other immobile trace elements (at equivalent silica levels), although the mobile radioactive heat-producing elements, K, Rb, Th, U, are significantly lower in the granulites. In both types the basic gneisses have moderately fractionated REE patterns while the intermediate and acid gneisses have strongly fractionated REE patterns with low heavy REE abundances and decreasing levels of total REE with increasing SiO₂. The most silicic gneisses develop large positive europium anomalies.These gross chemical similarities between gneisses from intermediate (amphibolite-facies) and lower (granulite-facies) crustal levels constrain models for the evolution of the Archaean crust. The depletion of K, Rb, Cs, Th and U in granulites, but not other incompatible trace elements cannot be explained by magmatic processes. The positive Eu anomaly in the more siliceous gneisses of both facies is a function of the primary processes of crustal generation and not secondary processes such as intracrustal melting or fractional crystallisation. Fractionation of radioactive heat-producing elements from other trace elements is a result of granulite-facies metamorphism with these elements being removed by an active fluid phase. The apparent lack of partial melting in lower crustal granulites suggests a model for Archaean crustal growth largely through underplating by primary tonalitic magmas.     

The effect of sewage sludge on salt-marsh denitrifying bacteria

Sewage sludge was applied biweekly to the soil surface of a shortSpartina alterniflora marsh in order to evaluate the marsh’s ability to assimilate the sludge nitrogen. After nine months there was a significant decrease of the denitrification potential in the first 15cm of the soil profile. In laboratory experiments the sludge was shown to have an immediate inhibitory effect on potential soil denitrification rates indicating that the decreasedin situ potential was probably a result of direct toxicity of the sludge on this bacterial respiratory process.     

Variations of the asymmetry of disk-integrated solar line profiles

Mean line bisector positions were found for the neutral iron line at 5250.2 using disk-integrated sunlight. After correction for the apparent time variation of the instrumental profile, it was found that the mean bisector position was constant during the period from May 1982 to February 1983.The correlation between the total magnetic flux as measured at Mount Wilson and the line asymmetry results of Livingston is not high. In particular, the magnetic flux dropped in 1982, suggesting a large line asymmetry that was not observed. However, the correlation between the 30-day average of the mean magnetic field and Livingston's results is quite high (-0.95), suggesting that the asymmetry of the disk-integrated line profile is related to the old plage regions rather than to the active regions.Now at the Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, U.S.A.