Preliminary results for a Russian designed explosive resistant container

The Russian Federal Nuclear Center Institute of Experimental Physics has completed a contract with Sandia National Laboratories to explore conceptual development of a family of containers capable of withstanding an internal explosion. The goal was containment of both the explosive force and hazardous by-products of a generic conventional explosive device. The Institute studied two designs, one for 2 kg and one for 50 kg of explosive. The designs were based on numerical calculations to extrapolate prior Russian design and experimental work to encompass these two cases. The Institute`s analyses indicate that they achieved excellent results for both a spherical and a cylindrical container made from a stainless steel/fiberglass composite construction. Both designs incorporate unique design features for door closures, internal shrapnel resistance, and shock attenuation. The project identified testing requirements, potential design feature improvements, as well as a sensitivity to the mass of packaging material around the explosive. We are pursuing these issues in a follow-on contract that is being negotiated

Biodiversité comparée des ripisylves du Rhône et de ses affluents (Cèze, Ouvèze, Durance) dans la région méditerranéenne.

Les forêts alluviales du Rhône méditerranéen, du Bas-Rhône à la Camargue, ont été affectées, durant le XIXe siècle, par les endiguements et la canalisation, qui ont provoqué un abaissement des niveaux moyens de nappe et une diminution des surfaces inondables. Ces forêts, intensivement exploitées durant des siècles, souffrent actuellement de grignotages pour l'agriculture ou les loisirs, et d'assèchement en raison des travaux hydrauliques. Cette étude tente de quantifier les pertes en habitats et en espèces végétales à la suite des travaux hydrauliques et des défrichements, par une comparaison entre les forêts alluviales du Bas-Rhône et celles de certains affluents mieux préservés (Ouvèze, Durance, Cèze). Des mesures de restauration sont proposées pour ces forêts remarquables

Quel système de référence pour la restauration des systèmes alluviaux rhénans ?

Floodplain ecosystems consist of a mosaic of shifting interactive habitats (forests, river channels and alluvial aquifers). Flood pulse, hydrological connectivity and geomorphological dynamics are key factors for high species diversity and productivity, complexity in successional trajectories and importance of ecotones between terrestrial and aquatic ecosystems. Most rivers in Europe have been drastically altered by dams and reservoirs, canalisation, reduction of the welland area, eutrophication and various other land-use developments. After a very long period of destruction of ftoodplain integrity, the need for protecting and restoring alluvial ecosystems slowly emerged over the last three decades. Restoration needs to define reference conditions, present conditions and restoration objective states, according to the principle of naturalness. This principle includes hydrological functionality (taking into account the flood pulse), the spatio-temporal diversity of habitat types and species, such as alluvial forest succession and connection of lateral arms to the active channel. We take examples in the upper Rhine valley to support the naturalness concept and to propose sorne principles on this basis for a restoration programme. The preservation of the hydrological functioning (i.e. flooding) ensures an efficient purifying capacity of the soil root system, with regard to phosphate and nitrate. As a consequence, groundwater nitrate and phosphate concentrations are very low under alluvial forests. Moreover the ftooding regime maintains a certain heterogeneity of aquatic and terrestrial habitats. The hydrological network, i.e. the former lateral arms, is supplied by different types of water (ground and/or surface water) and water quality differs according to their degree of conneclion to the active channel. The connected arms, is eutrophie whereas the disconnected arms evolve towards an oligotrophic state. The aquatic macrophytes communities reftect the change in water quality. The spatio- temporal variability of habitats is higher in the ftooded sectors than in the unftooded ones. As a consequence the ftooded sectors include more aquatic macrophytes communities (3 to 5 according to the hydrological year vs 2) and each community has greater species richness. A similar relationship exists for terrestrial habitats and forest communities. Hard wood forests tend to dominate the unftooded sectors whereas the flooded areas present a very rich spatio-tempoal mosaïc of forests units including all steps of the alluvial succession. The comparison of forest architecture between ftooded and unftooded sites shows that disconnection results in an increase of the ligneous density, a decrease of the tree height, the absence of treefall and a decrease of lianas (for example ivy).The Rhinau island, a still flooded sector in the Rhine floodplain can be used as a basis for the naturalness concept, due to the preservation of a certain functionnality, even if flooding duration is lower than before the Rhine canalisation (2 days versus 15 days). The two other sites, with differing durations of isolation (30 and 130 years), show different levels of change in floristic composition and structure of forests, and aquatic macrophyte communities . Accordingly, the restoration programme needs to engage more direct interventions. A key factor to emphasize should be the restoration of natural hydrological functioning. On the basis of the concept of naturalness, we therefore propose a four- step restoration programme : 1) restoration of free flow of water in the former lateral arms by connecting them to the river, 2) restoration of natural floods based on Rhine discharges, 3) development of a specific programme for the by-passed sections, 4) finally, development of the inter-connection of the restored areas along the riverLes zones alluviales, traversées par des flux d'eau et d'énergie fournis par un cours d'eau, sont organisées en ensembles fonctionnels interactifs associant des systèmes terrestres forestiers et/ou prairiaux et des systèmes aquatiques. Le fonctionnement par pulsations (« flood pulse »), la connectivité hydrologique et la dynamique géomorphologique sont les facteurs-clés de la diversité et de la productivité biologiques. Les aménagements hydrauliques des grands fleuves ont fortement réduit la surface du lit majeur et perturbé, voire supprimé, les fonctions d'écrêtement des crues, de recharge de la nappe, d'épuration des eaux et de diversité du complexe alluvial. Il est proposé de restaurer des zones inondables et de recréer ainsi des conditions favorables à la restitution de leurs fonctions. La restauration et la gestion de ces zones passent par la détermination de différents états, état de référence (celui du fleuve « sauvage » ), état actuel et état objectif sur la base du principe de naturalité. Ce principe inclut la fonctionnalité hydrologique (maintien d'un fonctionnement par pulsations), la diversité spatio-temporelle des habitats (conservation de la succession alluviale forestière, connexion des bras latéraux au fleuve) et des espèces. Au travers des exemples pris parmi les sites rhénans, présentant des degrés variables de naturalité, nous définissons les grands principes de mise en place d'un programme de restauration du Rhin supérieu

Water uptake by trees in a riparian hardwood forest (Rhine floodplain, France)

Water flow in the soil–root–stem system was studied in a flooded riparian hardwood forest in the upper Rhine floodplain. The study was undertaken to identify the vertical distribution of water uptake by trees in a system where the groundwater is at a depth of less than 1 m. The three dominant ligneous species (Quercus robur, Fraxinus excelsior and Populus alba) were investigated for root structure (vertical extension of root systems), leaf and soil water potential (m), isotopic signal (18O) of soil water and xylem sap. The root density of oak and poplar was maximal at a depth of 20 to 60 cm, whereas the roots of the ash explored the surface horizon between 0 and 30 cm, which suggests a complementary tree root distribution in the hardwood forest. The flow density of oak and poplar was much lower than that of the ash. However, in the three cases the depth of soil explored by the roots reached 1Ð2 m, i.e. just above a bed of gravel. The oak roots had a large lateral distribution up to a distance of 15 m from the trunk. The water potential of the soil measured at 1 m from the trunk showed a zone of strong water potential between 20 and 60 cm deep. The vertical profile of soil water content varied from 0Ð40 to 0Ð50 cm3 cm3 close to the water table, and 0Ð20 to 0Ð30 cm3 cm3 in the rooting zone. The isotopic signal of stem water was constant over the whole 24-h cycle, which suggested that the uptake of water by trees occurred at a relatively constant depth. By comparing the isotopic composition of water between soil and plant, it was concluded that the water uptake occurred at a depth of 20 to 60 cm, which was in good agreement with the root and soil water potential distributions. The riparian forest therefore did not take water directly from the water table but from the unsaturated zone through the effect of capillarit

Relations entre topographie, nature sédimentaire des dépôts et phytocénose dans le lit alluvial majeur sous forêt du Rhin dans le fossé rhénan : forêt de la Sommerley (commune d'Erstein)

Beziehungen zwischen Topographie, sedimentären Eigenschaften der Ablagerungen und Phytozönosen im bewaldeten Hochwasserbett des Rheins im Oberrheingraben : Sommerley (Erstein, Elsass). — Die Nachbildung der Sedimentstrukturen eines früheren Hochwasserbettes des heute kanalisierten Rheins bietet grosse Schwierigkeiten. Die traditionelle geomorphologische Anlage beiderseits der Niedrigwasserbetten ist fast systematisch gestört. Die geomorphologischen Taxa überlagern sich in verschiedenen Grössenklassen und die Topographie ist nie bezeichnend. Die genetische Ansprache der Ablagerungen ist unsicher. Der Geomorpholog kann sich jedoch auf den in diesem Milieu ausgezeichneten Anzeigerwert der Pflanzengesellschaften stützen. Einige Beispiele werden gegeben.Relations between topography, sedimentary nature of deposits and phytocenoses in the natural flood plain under forest of the Rhine in the upper Rhine graben. Sommerley Forest (Erstein, France). — In the reconstruction of the sedimentary arrangement of a former flood plain of the Rhine, which is now canalized, much difficulties arise. The classical geomorphological structure on the sides of a former channel is generally disrupted. Geomorphological taxons at différent scales overlap in a confuse manner, topography is rarely indicative. To settle the problem, a great help to geomorphologists is plotting of phyto associations the indicative character of which is particularly useful in this context. Some examples are given.La reconstitution des structures sédimentaires d'un secteur d'ancien lit majeur du Rhin, aujourd'hui canalisé, bute sur un certain nombre de difficultés. Ainsi, l'agencement traditionnel des formes à partir d'un chenal de lit mineur est presque systématiquement bouleversé : les taxons géomorphologiques s'imbriquent à différentes échelles et la topographie superficielle n'est jamais significative. De même, il est difficile d'attribuer une origine génétique sûre aux sédiments rencontrés. Pour démêler la situation, le géomorphologue peut, par contre, s'aider du relevé des associations végétales dont le rôle indicateur est ici particulièrement manifeste et utile. Quelques exemples en sont présentés.Carbiener P., Carbiener R., Vogt Henri. Relations entre topographie, nature sédimentaire des dépôts et phytocénose dans le lit alluvial majeur sous forêt du Rhin dans le fossé rhénan : forêt de la Sommerley (commune d'Erstein). In: Revue Géographique de l'Est, tome 33, n°4,1993. Vallées fluviales en Europe à l’Holocène. pp. 297-311

Quelques aspects des interactions entre litières forestières et écosystèmes aquatiques ou terrestres

We have examined the processes responsible for the disturbing effects of dead leaves in freshwater environments. The first is a biochemical deoxygenation caused by the polyphenoloxidase-polyphenol system, which remains active in dead leaves. The intensity of this effect considerably varies from species to species. It depends on the quantity and nature of the phenolic substrates, as well as of the phenoloxidase activities, the presence of variable amounts of phenoloxidase inhibitors such as tanins, and the aqueous extractibility of these agents. The deoxygenating effect of dead leaves macerates is immediate and intense for some species, for example Poplar and Ash, but weak for others, such as Oak and Birch. This first process is followed by two others : 1) microbiological deoxygenation and 2) spontaneous precipitation of phytomelanins resulting from their oxidative polycondensation. These phytomelanins have ion exchange and sequestration properties. Nevertheless their disturbing effects on the aquatic environment are poorly understood at the present time. A fourth process is the toxicity of leaf macerates. This toxicity is probably due to their phenolic compounds, their oxidation products, or other compounds such as saponosides. Thus the Birch, in spite of a very weak deoxygenating effects is very toxic for juvenile roaches. We studied these four different processes in ten different species, and we established their respective role in the pollution of freshwater by dead leaves. These roles are discussed in terms of the phylogeny of the tree species studied, as well as of the functionning of temperate forest ecosystems.Trémolières M., Carbiener Roland. Quelques aspects des interactions entre litières forestières et écosystèmes aquatiques ou terrestres. In: Revue d'Écologie (La Terre et La Vie), tome 40, n°4, 1985. pp. 435-449

Results of screening activities in salt states prior to the enactment of the Nationall Waste Policy Act

The identification of potential sites for a nuclear waste repository through screening procedures in the salt states is a well-established, deliberate process. This screening process has made it possible to carry out detailed studies of many of the most promising potential sites, and general studies of all the sites, in anticipation of the siting guidelines specified in the Nuclear Waste Policy Act. The screening work completed prior to the passage of the Act allowed the Secretary of Energy to identify seven salt sites as potentially acceptable under the provisions of Section 116(a) of the Act. These sites were formally identified by letters from Secretary Hodel to the states of Texas, Utah, Mississippi, and Louisiana on February 2, 1983. The potentially acceptable salt sites were in Deaf Smith and Swisher Counties in Texas; Davis and Lavender Canyons in the Gibson Dome location in Utah; Richton and Cypress Creek Domes in Mississippi; and Vacherie Dome in Louisiana. Further screening will include comparison of each potentially acceptable site against disqualification factors and selection of a preferred site in each of the three geohydrologic settings from those remaining, in accordance with the siting guidelines. These steps will be documented in statutory Environmental Assessments prepared for each site to be nominated for detailed characterization. 9 references