RELIABILITY AND MAINTAINABILITY CONCEPTS IN GENERATING STATION DESIGN

This thesis describes the elements of a formal Reliability and Maintainability Program which should be implemented by the electric power industry in the design of future generating stations, in order to improve their reliability and maintainability performance. The severe financial penalties of generating unit unreliability are discussed to emphasize the value of the proposed Program. Elements such as design specifications, target allocation, reliability and maintainability prediction and analysis, and design review are described, and a detailed example of reliability and maintainability target allocation to a 500 MW unit is included. Also presented are several prerequisites for an effective Reliability and Maintainability Program, such as the definition of supplier responsibility, criteria for supplier and equipment selection, data collection, and training of personnel. A reliability modelling and prediction technique known as derated state modelling is investigated. This technique is applied to the design of a typical boiler feed system, to show how a suitable design may be evolved with the use of reliability and maintainability

Characterization and performance evaluation of a helium recovery system designed for cold spraying

This paper describes and evaluates the performance of a Helium Recovery System (HRS) designed for cold spraying. A flexible, automated, full scale Helium Recovery System has been designed and installed in the McGill Aerospace Materials & Alloy Development Center Cold Spray Facility, located at and in collaboration with the National Research Council of Canada. The fully automated Helium Recovery System has been designed to recover helium from the cold spray chamber with sufficient purity (>99%) and flow capacity (5 to 220 Nm\ub3/h), allowing for a cost-effective operation by insuring a recovery rate of above 85%. In addition, a comparison of titanium coating properties obtained by using both He and N\u2082 as propellant gas is presented.Peer reviewed: YesNRC publication: Ye

Late Remodeling Around a Proximally HA-coated Tapered Titanium Femoral Component

Most bone remodeling is thought to occur within the first few years after THA. Loss of bone density later may be associated with stress shielding or normal bone loss of aging. We evaluated remodeling changes over time with a proximally hydroxyapatite-coated tapered titanium stem. We evaluated plain radiographs of 143 hips for cancellous condensation, cortical hypertrophy, cortical porosis, cortical index, and canal fill at early postoperative, 5, 10, and 15 years. Average age was 51 years at THA; 69 patients (77 hips) (53%) were women; and 102 hips (71%) had primary osteoarthrosis. Based on radiographic findings at 15 years, hips were divided into three subgroups: 43 (30%) demonstrated minimal remodeling changes; 53 (37%) demonstrated cortical hypertrophy evident before 5 years; and 47 (33%) demonstrated additional late remodeling and cortical porosis, most often after 10 years. Hips with poorer bone (Dorr Types B or C) and, when including only hips with osteoarthrosis, more female hips had cortical porosis at 15 years. Late radiographic changes in patients with porosis appear more similar to that associated with an extensively rather than proximally coated stem. Whether continued bone adaptation and bone loss of aging will eventually threaten implant stability is unknown, but at 15 years, all 143 implants remained well fixed and clinically asymptomatic