[en] Although Gentilly-2 reactor was planned to last for 30 years, its life could be significantly shorter if nothing were done, whereas retubing and refurbishment after, say, 25 years should result in an extension of service life to 45-50 years. In the long run, dimensional changes rather than hydriding may prove to be the pressure tubes' life limiting factor. Hydro Quebec, New Brunswick Power and AECL have an agreement to cooperate in developing a life management program for CANDU-6 reactors. The author expresses the opinion that cost-benefit criteria should be introduced in regulatory decision making. 6 refs., 9 figs

[en] Although Gentilly-2 reactor was planned to last for 30 years, its life could be significantly shorter if nothing were done, whereas retubing and refurbishment after, say, 25 years should result in an extension of service life to 45-50 years. In the long run, dimensional changes rather than hydriding may prove to be the pressure tubes' life limiting factor. Hydro Quebec, New Brunswick Power and AECL have an agreement to cooperate in developing a life management program for CANDU-6 reactors. 6 refs., 2 figs

[en] The station's maintenance policy aims at ensuring equipment availability through a management process seeking to balance resources and requirements. This policy has led to the implementation of a comprehensive preventive maintenance program. To improve overall performance to an annual availability factor of 90%, planned outages must be limited to 21 days a year, and the preventive maintenance program must be upgraded

[en] Comprehensive preventive maintenance programs at Gentilly-2 Nuclear Generating Station are based on a policy that seeks to balance requirements against resources. A commitment to total quality aims at performance improvement and total customer satisfaction. To improve overall performance to an annual availability factor of 90%, planned outages must be limited to 21 days per year, and the preventive maintenance program must be upgraded. A quality improvement team is involved in supporting this initiative. This team will seek to bring a new balance to the program, and eventually optimize it, using reliability-centred maintenance techniques. 24 figs

[en] Two low temperature metalorganic chemical vapor deposition growth techniques, the pre-cracking method and the plasma enhanced method, is discussed. The pre-cracking technique enables one to grow high quality epitaxial Hg_1-xCd_xTe on CdTe or CdZnTe substrates at temperatures around 200-250⁰C. HgTe-CdTe superlattices with sharp interfaces have also been fabricated. Furthermore, for the first time, the authors have demonstrated that ternary Hg_1-xCd_xTe compounds and HgTe-CdTe superlattices can be successfully grown by the plasma enhanced process at temperatures as low as 135 to 150⁰C. Material properties such as surface morphology, infrared transmission, Hall mobility, and interface sharpness are presented

[en] Vehicles typically deteriorate with accumulating mileage and emit more tailpipe air pollutants per mile. Although incentive programs for scrapping old, high-emitting vehicles have been implemented to reduce urban air pollutants and greenhouse gases, these policies may create additional sales of new vehicles as well. From a life cycle perspective, the emissions from both the additional vehicle production and scrapping need to be addressed when evaluating the benefits of scrapping older vehicles. This study explores an optimal fleet conversion policy based on mid-sized internal combustion engine vehicles in the US, defined as one that minimizes total life cycle emissions from the entire fleet of new and used vehicles. To describe vehicles' lifetime emission profiles as functions of accumulated mileage, a series of life cycle inventories characterizing environmental performance for vehicle production, use, and retirement was developed for each model year between 1981 and 2020. A simulation program is developed to investigate ideal and practical fleet conversion policies separately for three regulated pollutants (CO, NMHC, and NO_x) and for CO₂. According to the simulation results, accelerated scrapping policies are generally recommended to reduce regulated emissions, but they may increase greenhouse gases. Multi- objective analysis based on economic valuation methods was used to investigate trade-offs among emissions of different pollutants for optimal fleet conversion policies. (author)

[en] Dynamic susceptibility contrast magnetic resonance imaging (DSC MRI) provides a noninvasive means to create high resolution maps of the regional distribution of cerebral blood volume (CBV). Most DSC MRI studies conducted to date have focused on the evaluation of patients with cerebral neoplasms, ischemia or infarction, and epilepsy. However, preliminary work suggests that DSC MRI may also provide clinically important information for the evaluation of patients with neuropsychiatric disorders, especially dementia and schizophrenia. Additionally, with appropriate modification, DSC MRI may be used to reliably evaluate the effects of pharmacological challenges on cerebral hemodynamics. As pharmacotherapy is an important component in the treatment of a range of psychiatric disorders, the dynamic assessment of changes in cerebral perfusion associated with drug administration may ultimately lead to the development of ''brain function tests'' for a wide range of disorders. (orig.)