Field Attractants for Pachnoda interrupta Selected by Means of GC-EAD and Single Sensillum Screening

The sorghum chafer, Pachnoda interrupta Olivier (Coleoptera: Scarabaeidae: Cetoniinae), is a key pest on sorghum, Sorghum bicolor (L.) Moench (Poaceae), in Ethiopia. At present there is a lack of efficient control methods. Trapping shows promise for reduction of the pest population, but would benefit from the development of attractive lures. To find attractants that could be used for control of P. interrupta, either by mass trapping or by monitoring as part of integrated pest management, we screened headspace collections of sorghum and the highly attractive weed Abutilon figarianum Webb (Malvaceae) for antennal activity using gas chromatograph-coupled electroantennographic detection (GC-EAD). Compounds active in GC-EAD were identified by combined gas chromatography and mass spectrometry (GC-MS). Field trapping suggested that attraction is governed by a few influential compounds, rather than specific odor blends. Synthetic sorghum and abutilon odor blends were attractive, but neither blend outperformed the previously tested attractants eugenol and methyl salicylate, of which the latter also was part of the abutilon blend. The strong influence of single compounds led us to search for novel attractive compounds, and to investigate the role of individual olfactory receptor neurons (ORNs) in the perception of kairomones. We screened the response characteristics of ORNs to 82 putative kairomones in single sensillum recordings (SSR), and found a number of key ligand candidates for specific classes of ORNs. Out of these key ligand candidates, six previously untested compounds were selected for field trapping trials: anethole, benzaldehyde, racemic 2,3-butanediol, isoamyl alcohol, methyl benzoate and methyl octanoate. The compounds were selected on the basis that they activated different classes of ORNs, thus allowing us to test potential kairomones that activate large non-overlapping populations of the peripheral olfactory system, while avoiding redundant multiple activations of the same ORN type. Field trapping results revealed that racemic 2,3-butanediol is a powerful novel attractant for P. interrupta

Within-pin 238U-capture distributions: CASMO-4 and MCNP vs. activation foil measurements

The design of modern BWR assemblies is governed by general requirements such as safe and reliable performance, optimal fuel utilization and cycle length, and a high degree of flexibility in reactor operation. These requirements are fulfilled via the use of increased enrichments, high gadolinium loadings and part-length fuel rods, which lead to very heterogeneous assembly designs, causing not only large variations in the power density of individual fuel pins, but also strong radial and azimuthal gradients in reaction rate distributions within the pins themselves. The invasive technique of activation foils (depleted uranium) is applied and the experimental results are compared with calculations performed using the deterministic code CASMO-4 as well as the stochastic code MCN

Radial and azimuthal 235U fission and 238U capture distributions in BWR UO2 pins: CASMO-4 and MCNP4C versus activation foil measurements

In the context of the LWR-PROTEUS program, radial and azimuthal 235U fission (F5) and 238U capture (C8) rate distributions have been calculated for zero-burnup pins of a Westinghouse SVEA-96 Optima2 boiling water reactor fuel assembly using the stochastic MCNP4C and the deterministic CASMO-4 codes. The within-pin F5 distributions predicted by the two codes are in very good agreement; the C8 distributions are more pronounced, and there are significant discrepancies between the codes, both azimuthally and radially. The calculations have been compared with experimental results obtained from activation foil measurements in two pins of the assembly irradiated in the center of the PROTEUS test zone. The measurements confirm that the two codes can accurately predict the radial and azimuthal F5 distributions but that MCNP4C within-pin C8 distributions are much more accurate than those of CASMO-

Advanced foil activation techniques for the measurement of within-pin distributions of the 63Cu(n,)64Cu reaction rate in nuclear fuel

Different foil activation techniques have been used for measuring spatial distributions of the 63Cu(n,)64Cu reaction within two pins of a SVEA-96 Optima2 boiling water reactor fuel assembly, at the critical facility PROTEUS. This reaction is of interest because its 1/v cross-section gives it a good representation of the 235U fission rate. Initially, radial capture rate profiles were measured with mechanically punched copper foils. More detailed profiles were then determined by using a 0.2 mm copper wire spiral (~200 m resolution), as well as 5-, 10-, and 20-ring UV-lithography, electroplating, and molding (UV-LIGA) foils (up to a 100 m resolution). For azimuthal measurements, apart from manually cut activation foils (into 8 sectors), 8- and 12-sector LIGA foils were used. The highly versatile LIGA foils have the additional advantage of being very easily separated into individual pieces after irradiation without the use of punches or other cutting tools. In order to account for the invasive character of the foil activation techniques, corrections to account for sample perturbations and for self-shielding effects were determined via simplified Monte Carlo (MCNP4C) modeling of the experimental setup. The final results from the various measurements of 63Cu(n,)64Cu within-pin distributions have been compared with MCNP computations employing a detailed model of the full SVEA Optima2 fuel assembl