[en] This paper discusses the growth in the seismic industry as a result of the recent increases in the foreign market. With the decline of communism and the opening of Latin America to exploration, seismic teams have moved out into these areas in support of the oil and gas industry. The paper goes on to discuss the improved technology available for seismic resolution and the subsequent use of computers to field-proof the data while the seismic team is still on-site. It also discusses the effects of new computer technology on reducing the amount of support staff that is required to both conduct and interpret seismic information

[en] Observations are made on nuclear reactor risks, on the basis of safety studies by or for U.S., U.K. and Swedish official organisations. It is argued that the risks have been under-estimated and that some aspects have been neglected. (U.K.)

[en] The Cementitious Barriers Partnership (CBP) was created to develop predictive capabilities for the aging of cementitious barriers over long timeframes. The CBP is a multi-agency, multi-national consortium working under a U.S. Department of Energy (DOE) Environmental Management (EM-21) funded Cooperative Research and Development Agreement (CRADA) with the Savannah River National Laboratory (SRNL) as the lead laboratory. Members of the CBP are SRNL, Vanderbilt University, the U.S. Nuclear Regulatory Commission (USNRC), National Institute of Standards and Technology (NIST), SIMCO Technologies, Inc. (Canada), and the Energy Research Centre of the Netherlands (ECN). A first step in developing advanced tools is to determine the current state-of-the-art. A review has been undertaken to assess the treatment of cementitious barriers in Performance Assessments (PA). Representatives of US DOE sites which have PAs for their low level waste disposal facilities were contacted. These sites are the Idaho National Laboratory, Oak Ridge National Laboratory, Los Alamos National Laboratory, Nevada Test Site, and Hanford. Several of the more arid sites did not employ cementitious barriers. Of those sites which do employ cementitious barriers, a wide range of treatment of the barriers in a PA was present. Some sites used conservative, simplistic models that even though conservative still showed compliance with disposal limits. Other sites used much more detailed models to demonstrate compliance. These more detailed models tend to be correlation-based rather than mechanistically-based. With the US DOE's Low Level Waste Disposal Federal Review Group (LFRG) moving towards embracing a risk-based, best estimate with an uncertainties type of analysis, the conservative treatment of the cementitious barriers seems to be obviated. The CBP is creating a tool that adheres to the LFRG chairman's paradigm of continuous improvement

[en] Since operating nuclear power plants age like any other type of industrial facility and most will expire in the early 21st century, some utilities are beginning to examine the possibility of extending plant life. A description of actions taken to extend the life of four units covers the programs at Fort Calhoun at Omaha, ANO-1 in Arkansas, San Onofre-1 in Southern California, and Commonwealth Edison's Dresden-2 and -3 units. Programs at each unit stress maintenance, component replacement instead of repair, and materials aging

[en] The aim of this work was to provide information which could be used to improve the efficiency and cost effectiveness with which regular calibrations and checks of area survey instruments and personal dosemeters are carried out. To this end the variation in fractional scatter component with distance from the neutron source has been determined using calculation, spectrometry and by reviewing the results of calibrations carried out since 1989, together with studies performed at NPL in 1982 and 1988. Scatter fraction relationships have been produced for ²⁴¹Am-Be and ²⁵²Cf sources, in terms of neutron fluence, ambient dose equivalent and instrument responses. (author)

[en] The primary aim of the study was to quantify the effects of photosynthetically-active radiation (PAR) on extension of leaves of silver birch (Betula pendula Roth.) and sycamore (Acer pseudoplatanus L.). Plants grown at 250 μ mol m^-2 s^-1 were exposed to a range of fluence rates (0-680 μ mol m^-2 s^-1) whilst enclosed in Perspex chambers in which temperature, vapour pressure deficit and photoenvironment were all controlled. Measurements of leaf extension, water relations, and cell wall extensibility (WEX) were made at the end of a 3 h exposure period. For leaves of birch, reducing the fluence rate resulted in reduced leaf extension and a lowering of WEX. Exposure of sycamore seedlings for 3 h to different values of PAR had little effect on the growth of leaves and WEX remained constant. The characteristics of net photosynthesis also differed for the two species and photosynthesis and wall loosening may be linked. Since natural woodland shadelight, in addition to reduced PAR, also has a reduced R/FR ratio, a second group of seedlings were placed in a photoenvironment which simulated shadelight (low PAR, R/FR) for 28 d. This treatment reduced extension rate and final leaf size for both species. Measurements of extension, water relations and WEX made when seedlings were exposed to shadelight whilst held in the Perspex chambers revealed differences in the control of leaf growth for the two species. It is confirmed that leaves of birch are highly responsive to changes in PAR with cell wall loosening the most likely process controlling this response

No abstract available

[en] A measurement of the response function for a neutron personal dosemeter normally involves a very extensive series of measurements with accelerator-produced monoenergetic neutrons. These are. expensive, and are often impractical for dosimetry services wishing to investigate their dosemeters, particularly if they are attempting to improve the dosemeter response and wish to investigate the effects of various changes in design or processing. A technique is described whereby the variation of the neutron energy with angle for neutron producing reactions such as ⁷Li(p,n)⁷Be and T(p,n)³He is utilized to irradiate a number of dosemeters to a range of energies in a single experiment. This report describes the characteristics, in particular the angular distribution of the fluence, of three fields covering the energy ranges, 101 to 250 keV, 336 to 565 keV, and 561 to 1200 keV, which between them cover the important energy region where fast-neutron personal dosemeters have a threshold in their detection sensitivity, and where detailed information about the response function is particularly important. Note: all uncertainties quoted in this report are estimates of standard (1σ) uncertainties representing a confidence level of approximately 67%. (author)

[en] An investigation was conducted to compare and evaluate contaminant transport results of two model codes, GoldSim and Porflow, using a simple 1-D string of elements in each code. Model domains were constructed to be identical with respect to cell numbers and dimensions, matrix material, flow boundary and saturation conditions. One of the codes, GoldSim, does not simulate advective movement of water; therefore the water flux term was specified as a boundary condition. In the other code, Porflow, a steady-state flow field was computed and contaminant transport was simulated within that flow-field. The comparisons were made solely in terms of the ability of each code to perform contaminant transport. The purpose of the investigation was to establish a basis for, and to validate follow-on work that was conducted in which a 1-D GoldSim model developed by abstracting information from Porflow 2-D and 3-D unsaturated and saturated zone models and then benchmarked to produce equivalent contaminant transport results. A handful of contaminants were selected for the code-to-code comparison simulations, including a non-sorbing tracer and several long- and short-lived radionuclides exhibiting both non-sorbing to strongly-sorbing characteristics with respect to the matrix material, including several requiring the simulation of in-growth of daughter radionuclides. The same diffusion and partitioning coefficients associated with each contaminant and the half-lives associated with each radionuclide were incorporated into each model. A string of 10-elements, having identical spatial dimensions and properties, were constructed within each code. GoldSim's basic contaminant transport elements, Mixing cells, were utilized in this construction. Sand was established as the matrix material and was assigned identical properties (e.g. bulk density, porosity, saturated hydraulic conductivity) in both codes. Boundary conditions applied included an influx of water at the rate of 40 cm/yr at one end of the string and no-flow lateral flow boundaries. A unit quantity of each contaminant was introduced at the influx boundaries and the rate of outflux at the opposite end of the 10-element string was recorded to make the comparisons. Saturated conditions were assumed in this evaluation. Under these carefully controlled conditions the two codes produced essentially identical results, demonstrating that both codes appear to be accurately implementing the contaminant transport mechanisms. The conclusion is that a satisfactory basis was established to justify the exercise in which 1-D GoldSim model was benchmarked against the 2-D unsaturated zone and 3-D saturated zone Porflow models used at the Savannah River Site (SRS).

[en] Neutrinos have intrigues physicists for over 60 years, yet it still is not determined if they possess a mass. Spontaneous oscillations between the various types of neutrinos, in analogy with the observed flavour oscillations between quarks, would be irrefutable evidence for non-zero neutrino mass. A group of experimental physicists from Australia has joined a new experiment to search for neutrino oscillations and this article reviews the importance of searching for such phenomena. 4 refs., 4 figs