No abstract available

[en] Waste Management Area 'A' (WMA 'A'), located in the outer area of the Chalk River Laboratories (CRL) was in use as a waste burial site from 1946 to 1955. Waste management structures include debris-filled trenches, concrete bunkers and miscellaneous contaminated solid materials, and ditches and pits used for liquid dispersal. In order to update historical records, it was proposed to conduct detailed ground geophysical surveys to define the locations of waste management structures in WMA 'A', assist in planning of the drilling and sampling program to provide ground truth for the geophysics investigation and to predict the nature and locations of unknown/undefined shallow structures. A detailed ground geophysical survey grid was established with a total of 127 grid lines, oriented NNE and spaced one metre apart. The geophysical surveys were carried out during August and September, 1996. The combination of geophysical tools used included the Geonics EM61 metal detector, the GSM-19 magnetometer/gradiometer and a RAMAC high frequency ground penetrating radar system. The geophysical surveys were successful in identifying waste management structures and in characterizing to some extent, the composition of the waste. The geophysical surveys are able to determine the presence of most of the known waste management structures, especially in the western and central portions of the grid which contain the majority of the metallic waste. The eastern portion of the grid has a completely different geophysical character. While historical records show that trenches were dug, they are far less evident in the geophysical record. There is clear evidence for a trench running between lines 30E and 63E at 70 m. There are indications from the radar survey of other trench-like structures in the eastern portion. EM61 data clearly show that there is far less metallic debris in the eastern portion. The geophysical surveys were also successful in identifying previously unknown locations of waste management structures within WMA 'K'. (author)

[en] The soft X-ray reflectivity characterization of Mo/Si multilayer deposited by electron beam evaporation is discussed. The measurements are performed on Indus-1 synchrotron storage ring. The interdiffusion of two-layer materials in multilayer leads to the formation of interlayers. To understand the influence of interlayers and interfacial roughness on soft X-ray reflectivity profile, simulation studies are performed. The roughness parameter leads to reduction in peak reflectivity whereas the interlayers significantly change the reflectivity profile. For fitting the angle-dependent soft X-ray reflectivity profile, a four-layer model accounts for the interlayers formed at the interfaces. Asymmetry at the two interfaces, viz. Si-on-Mo and Mo-on-Si needs to be considered for a good model fitting of the soft X-ray reflected profile. The mechanism, which could lead to the formation of interlayers in Mo/Si multilayer is discussed

[en] An IBM-PC/XT based data acquisition system for nuclear spectroscopic work has been designed to accept data simultaneously from multiple multi channel analysers. The data transfer is implemented using a low cost commercially available I/O add-on card for the IBM-PC/XT. All handshaking signals are generated by software. The input data can be accepted in serial and/or parallel mode. For processing the data thus aquired, a software package SPECTRUM has been developed. (author). 4 figs

[en] Most concepts for the deep geological disposal of spent nuclear fuel involve the permanent emplacement of containers of conditioned fuel in a geological repository, with no expectation of retrieval. A geological repository will consist of a large number of disposal rooms excavated at depths of a few hundred metres to more than one thousand metres within a suitable geological formation like crystalline rock, salt, shale, clay or tuff. The Atomic Energy Control Board (AECB), on behalf of Canada, is assisting the International Atomic Energy Agency (IAEA) in developing monitoring techniques for safeguards for spent fuel in geological repositories (SAGOR). AECL, in co-operation with the AECB, has conducted a study of existing and potential geophysical techniques that might be applicable to the safeguards monitoring of spent fuel containers in geologic repositories. Electromagnetic, magnetic, radiometric and ground penetrating radar surveys from the floor of the rooms containing back-filled emplacement boreholes can assist in monitoring the continued presence of the containers of spent fuel during the operation of repositories. The high frequency seismic reflection technique and digital ground penetrating radar technique tested for mapping fracture zones within a 50 m exclusion distance for the Canadian disposal concept provides encouragement for monitoring the presence of undeclared diversion tunnels or rooms. Acoustic Emission/Micro-seismic monitoring technique with suitably deployed sensors can provide advance warning of any active undeclared excavations. Recent improvements in instrumentation, collection of multiple sensor data by remotely controlled vehicles and fast data processing techniques have advanced the feasibility of using these techniques during the day-to-day operations of repositories. The techniques discussed with the limited exception of AE/MS, borehole radar, surface radar and seismic reflection are not yet directly tested in experimental/real repository environments. The continued follow up of the developments of multiple sensor platforms and developing case history examples from experimental repository environments will provide confidence in the application of geophysical techniques for repository safeguards. Assuring the continued presence of spent fuel after repository closure by monitoring unauthorized excavations presents additional challenges. (author)

[en] Gold concentration in Indus river sediments have been estimated using energy dispersive X-ray fluorescence (EDXRF) spectrometry. To get the best possible detection sensitivity, optimisation of sample preparation procedure and exciting radiation was done. Physical preconcentration procedure of panning of heavy minerals has been employed. Samples were dissolved in acqua regia to homogenize the distribution of gold. For obtaining an optimum excitation sensitivity, radioisotope sources of various energies as well as a low power laboratory built transmission type Mo X-ray tube have been used. L shell X-rays of gold have been used for qualitative analysis. For quantitative estimation, a combination of single element fundamental parameter method and scattered radiation standardisation method was used. The sensitivity of EXDRF spectrometer for gold was around 50 ppm. (author). 6 figs., 2 tables

[en] Optical design of a soft and deep x-ray lithography beamline to be installed on Indus-2 is reported. The beamline consisting of a plane and toroidal mirror will provide wide lithographic window (1 keV-18 keV). It can also be operated in no optics mode. Spot diagrams of beam image at mask-wafer stage, effect of mirror movements, power density and spatial resolution are analyzed using ray-tracing. (author)

[en] Multilayer period thickness changes for various thickness ratios, Γ (ratio of W layer thickness to period thickness) as a function of annealing temperatures were studied by grazing incidence X-ray reflectivity (GIXRR), and grazing incidence X-ray diffraction (GIXRD). Both period thickness expansion and compression were observed depending upon Γ and annealing temperatures. Multilayer with the W layer thickness close to the B_4C layer has undergone less period thickness changes. Successive appearance and disappearance of multilayer Bragg maxima in GIXRR were observed. Such behavior suggested that redistribution of atomic density within bilayer, the displacement of interface and the multilayer period thickness change as annealing proceeds. GIXRD measurements performed using synchrotron radiation suggested the formation of phases corresponding to tungsten boride and carbide. - Highlights: • We reported the influence of the layer thickness on thermal stability of W/B_4C multilayers. • Depending on the layer thickness ratio, the period variation can be positive or negative. • Diffusion induced structural changes can be minimized by optimizing layers thickness ratio. • Tungsten carbide and boride phases observed at elevated temperatures

[en] Helium gas was injected at constant pressure into an inclined fracture zone through an access borehole at a depth of about 40 m, in the Lac du Bonnet granite, southeastern Manitoba. The gas flow rate, arrival time and pattern of distribution of gas at the surface were monitored by soil gas surveys. The field results were compared with predictions of a simple analytical model derived from Thunvik and Braester (1987). Good agreement was found when the influence of vertical fracturing in the bedrock and a low-permeability overburden were included in the model. The model was then used to determined the hydraulic conductivity of individual gas flow paths in the fractured rock. (author). 23 refs., 5 tabs., 37 figs

[en] Development of multilayer coating is playing an important role in the exploitation of soft x-ray/extreme ultra violet (XUV) region of the electromagnetic spectrum. Multilayers are being developed by us, with an objective to develop optical elements for synchrotron radiation applications. XUV multilayers are fabricated using an ultra high vacuum electron beam deposition system. Interface characterizations are done using grazing incidence x-ray reflectivity, x-ray scattering and cross sectional transmission electron microscopy measurements. Normal incidence XUV reflectivity performance is done on Indus-1 reflectometry beamline. (author)