The implementation of a risk based maintenance policy to a power plant

Krishnasamy, Loganathan (2004) The implementation of a risk based maintenance policy to a power plant. Masters thesis, Memorial University of Newfoundland.

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Abstract

The unexpected failures, the down time (outage) associated with such failures, the loss of production of power and, the higher maintenance costs are major problems in operation of thermal power plants. The unexpected failure of an equipments and systems causes economic risk and can be minimized using an effective maintenance strategy. The risk based approach ensures a strategy, which is cost effective. Such an approach uses the information obtained from the study of failure modes and their consequences. -- The purpose of the thesis is to develop and show how to implement a risk based maintenance (RBM) policy to a power plant. This quantitative approach will provide a basis for selection of the best alternative strategy to minimize the risk resulting from breakdowns or failures. -- The proposed methodology is comprised of three modules: risk assessment, risk evaluation, and maintenance planning. This work presents a mechanism for the study of the occurrence of failures and functional failures in equipment and the severity of their consequences, known as risk. Maintenance of equipment is prioritized based on the risk, and the reduction in overall risk of the plant is accomplished by focusing on the maintenance of high-risk items first. To the author's knowledge this quantitative approach has not been developed before. -- The study is conducted for Newfoundland and Labrador Hydro, Holyrood thermal power generation plant. Failure data is collected from the existing power station (Unit 3-150 MW) over a period of twelve years. The data is modeled using Weibull and Exponential distributions to estimate the parameters. A probabilistic risk analysis is performed to quantify the risk at the plant. An acceptable risk criterion is determined and the major systems and subsystems that are found to have a risk higher than acceptable risk are identified. The maintenance interval is calculated by reverse or target probability analysis for reducing the level or risk resulting from the failure of a system. -- To conclude, the risk based maintenance strategy can be employed to prioritize the systems for maintenance planning, and to improve the existing maintenance policies. In addition, this strategy provides cost-effective means for maintenance as well it minimizes the consequences (safety, economic and environment) related to a system failure.

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