Effects of liquid and vapor cesium on structural materials

Literature survey on corrosive effects of liquid and vapor cesium on structural materials, and compatibility of cesium as working fluid for Rankine cycle space power plan

Demographics of a Geographically-Isolated Population of Threatened Salamander (Caudata: Ambystomatidae) in Central Illinois

Amphibian populations that use small isolated wetlands are often small in size, susceptible to stochastic extinction processes, and have little to no contact with other populations. One can ascertain the persistence of such populations only by obtaining data that allow the prediction of future changes in population’s size, and propensity to achieve a sustainable number of individuals. The number of metamorphosing larvae leaving a pond predicts the viability of a salamander population, and thus, the number recruited into the terrestrial adult population. The Jefferson Salamander, Ambystoma jeffersonianum, is a listed threatened species in Illinois, occurring at fewer than 15 ponds statewide. In 2004 and 2005, individuals at an isolated breeding pond in Lincoln Trail State Recreation Area (LTSRA) were captured using a drift fence-pitfall trap array. Once captured, we determined sex, measured snout-vent length, and using a unique combination of toe clips, marked the salamanders. We also determined the number of egg masses, average percentage of successfully hatched eggs, and number of juveniles leaving the pond. We incorporated this information into a matrix for a stage-based population model. Model simulations predicted that on average, the population at the LTSRA pond would persist for four more years, with survivorship from larvae to juvenile being the most important parameter. Increasing survivorship during the larval period increased abundance as well as average persistence time. Active management at the breeding pond to increase the time available for successful metamorphosis might facilitate persistence of the salamander at this site

Demographics of a Geographically-Isolated Population of Threatened Salamander (Caudata: Ambystomatidae) in Central Illinois

Amphibian populations that use small isolated wetlands are often small in size, susceptible to stochastic extinction processes, and have little to no contact with other populations. One can ascertain the persistence of such populations only by obtaining data that allow the prediction of future changes in population’s size, and propensity to achieve a sustainable number of individuals. The number of metamorphosing larvae leaving a pond predicts the viability of a salamander population, and thus, the number recruited into the terrestrial adult population. The Jefferson Salamander, Ambystoma jeffersonianum, is a listed threatened species in Illinois, occurring at fewer than 15 ponds statewide. In 2004 and 2005, individuals at an isolated breeding pond in Lincoln Trail State Recreation Area (LTSRA) were captured using a drift fence-pitfall trap array. Once captured, we determined sex, measured snout-vent length, and using a unique combination of toe clips, marked the salamanders. We also determined the number of egg masses, average percentage of successfully hatched eggs, and number of juveniles leaving the pond. We incorporated this information into a matrix for a stage-based population model. Model simulations predicted that on average, the population at the LTSRA pond would persist for four more years, with survivorship from larvae to juvenile being the most important parameter. Increasing survivorship during the larval period increased abundance as well as average persistence time. Active management at the breeding pond to increase the time available for successful metamorphosis might facilitate persistence of the salamander at this site

Demographics of a Geographically-Isolated Population of Threatened Salamander (Caudata: Ambystomatidae) in Central Illinois

Amphibian populations that use small isolated wetlands are often small in size, susceptible to stochastic extinction processes, and have little to no contact with other populations. One can ascertain the persistence of such populations only by obtaining data that allow the prediction of future changes in population’s size, and propensity to achieve a sustainable number of individuals. The number of metamorphosing larvae leaving a pond predicts the viability of a salamander population, and thus, the number recruited into the terrestrial adult population. The Jefferson Salamander, Ambystoma jeffersonianum, is a listed threatened species in Illinois, occurring at fewer than 15 ponds statewide. In 2004 and 2005, individuals at an isolated breeding pond in Lincoln Trail State Recreation Area (LTSRA) were captured using a drift fence-pitfall trap array. Once captured, we determined sex, measured snout-vent length, and using a unique combination of toe clips, marked the salamanders. We also determined the number of egg masses, average percentage of successfully hatched eggs, and number of juveniles leaving the pond. We incorporated this information into a matrix for a stage-based population model. Model simulations predicted that on average, the population at the LTSRA pond would persist for four more years, with survivorship from larvae to juvenile being the most important parameter. Increasing survivorship during the larval period increased abundance as well as average persistence time. Active management at the breeding pond to increase the time available for successful metamorphosis might facilitate persistence of the salamander at this site

Thermoregulation of Male Elaphe Spiloides in an Agriculturally-Fragmented Forest in Illinois

Anthropogenic forest fragmentation increases the amount of edge habitat. Although edges are harsh environments for many native species, ratsnakes often prefer this habitat. We examined thermoregulatory effectiveness of Central Ratsnakes (Elaphe spiloides) using forest edges preferentially to determine if edge preference is driven by increased thermoregulatory efficiencies. Six male subjects were located every 1-2 days using radio-telemetry and temperature sensitive transmitters. Subjects did not thermoregulate more efficiently in edges than in forest. Snakes were thermoconformers in both habitat types suggesting edge preference might be driven by other factors

Irradiation damage of ferritic/martensitic steels: Fusion program data applied to a spallation neutron source

Ferritic/martensitic steels were chosen as candidates for future fusion power plants because of their superior swelling resistance and better thermal properties than austenitic stainless steels. For the same reasons, these steels are being considered for the target structure of a spallation neutron source, where the structural materials will experience even more extreme irradiation conditions than expected in a fusion power plant first wall (i.e., high-energy neutrons that produce large amounts of displacement damage and transmutation helium). Extensive studies on the effects of neutron irradiation on the mechanical properties of ferritic/martensitic steels indicate that the major problem involves the effect of irradiation on fracture, as determined by a Charpy impact test. There are indications that helium can affect the impact behavior. Even more helium will be produced in a spallation neutron target material than in the first wall of a fusion power plant, making helium effects a prime concern for both applications. 39 refs., 10 figs

Elevated-Temperature Ferritic and Martensitic Steels and Their Application to Future Nuclear Reactors

In the 1970s, high-chromium (9-12% Cr) ferritic/martensitic steels became candidates for elevated-temperature applications in the core of fast reactors. Steels developed for conventional power plants, such as Sandvik HT9, a nominally Fe-12Cr-1Mo-0.5W-0.5Ni-0.25V-0.2C steel (composition in wt %), were considered in the United States, Europe, and Japan. Now, a new generation of fission reactors is in the planning stage, and ferritic, bainitic, and martensitic steels are again candidates for in-core and out-of-core applications. Since the 1970s, advances have been made in developing steels with 2-12% Cr for conventional power plants that are significant improvements over steels originally considered. This paper will review the development of the new steels to illustrate the advantages they offer for the new reactor concepts. Elevated-temperature mechanical properties will be emphasized. Effects of alloying additions on long-time thermal exposure with and without stress (creep) will be examined. Information on neutron radiation effects will be discussed as it applies to ferritic and martensitic steels