Behavioral studies of surge protection components

In our daily life, almost all the items we used, being a computer, television, lift or vehicle we drive consist of some kind of electrical or electronics component inside. The operation of these devices could be severely affected by lightning activity or electrical switching events, as there are more than 2000 thunderstorms in progress at any time resulting in 100 lightning flashes to ground per second. In practice, any device using electricity will subject to surge damages induced from the lightning or switching of heavy load. Surge protection device (SPD) is added at the power distribution panel and critical process loop to prevent damage subsequently cause plant shutdown. There are many questions raised on the SPD. How can this small device protect the equipment from large energy release by the lightning? What is inside the device? How does it work? This paper provides comprehensive detail in revealing the science and engineering behind the SPD, its individual component characteristic and how does it work. The technical information presented is limited to surge protection on equipment; surge protection for building structure will not be discussed here.

Single Point Vulnerabilities Management Strategy of Qinshan Nuclear Power Plant

A SPV (Single Point Vulnerability) analysis consists of a list of trains, components or tag IDs, any which could result in a plant shutdown or significant load reduction were the affected equipment be unable to perform its function in supporting generation. Usually, a SPV related components or tag IDs that are identified as a part of an AP-913 based component criticality analysis. But how can we build a solid SPV component management strategy is a key issue for a heathy equipment reliability process. This paper developed a good practices to integrated SPV which related to the generation risk management into the equipment reliability process.

HEAVY METAL POLLUTION OF RIVER WATERS AND COASTAL SOILS ADJACENT TO THE TAILING STORAGE FACILITY TERRITORY

Introduction. The operation of the Teghut copper-molybdenum enterprise resulted in the man-made load on the environments in terms of concentrations of some heavy metals (autumn 2016), the migration of which continued even after the plant shutdown (autumn 2018). Methods. The authors studied changes in the concentrations of Mo, Zn, and Cu in samples of Shnogh River water and coastal soils near the tailing storage facility territory. Results. During enterprise operation, in water sampling points 1 and 2, a decrease in the concentrations of these heavy metals after the plant shutdown was noted. According to the analysis of coastal soil samples, in points 1 and 2, after the plant shutdown, the Zn concentration decreased by 75% and the Cu concentration decreased by 84% compared with the analysis of samples during enterprise operation. In samples of coastal soils from sampling points 3 and 4, a concentration reverse was observed. Conclusion. The calculation of the geo-accumulation coefficient for the studied heavy metals in soil sampling points 1 and 2 compared to sampling points 3 and 4 indicates a decrease in the man-made load on the environment, caused by plant operation.

Modeling Solar Converters for Harmonic and Resonance Studies

Solar and renewable plants are increasingly being added to national grids. One technical drawback of renewable generators is that they tend to cause a significant harmonic distortion of the current and voltage waveforms. The harmonic distortions are amplified when the natural resonances of the grid interact with the injected harmonics from the power electronic based PV generation. A sustained harmonic distortion can lead to equipment failure, reduced plant output or a complete plant shutdown. Therefore, it is important to study harmonic interactions and resonance issues using fully detailed EMT models before the commissioning of a renewable plant. This paper outlines important features of modelling solar converters for the use of harmonic and resonance studies.

The extended living probabilistic safety assessment

The term living probabilistic safety assessment was defined soon after the initial probabilistic safety assessments were implemented. The objective of this article is to present the extended living probabilistic safety assessment and its applications considering realistic nuclear power plant models, including the low power and shutdown plant operating states. One of the key objectives is to compare the suitability of conventional and additional risk measures, core damage frequency and conditional core damage frequency, respectively. The methods are presented considering all states of the plant from the full power operation to the low power and shutdown states. The example models of the nuclear power plants and the results of the living probabilistic safety assessment of the plant operating states are discussed. The results show that the risk of low power and shutdown states is generally smaller than the risk of full power operation, but the low power and shutdown plant operating states differ significantly among each other regarding the risk level. The deficiency of living probabilistic safety assessment applied to the plant shutdown states is connected with significantly increased human effort for the analyses, with a significantly greater amount of results and with increased uncertainty of some parameters due to the larger dynamics of actions in the plant shutdown versus the full power operation states. The benefit of the living probabilistic safety assessment applied to the plant low power and shutdown states lays in consideration of all states and potential identification of risk significant states and directions for possible safety improvements.

Quality improvement through ergonomics intervention at chemical plant

Purpose This paper aims to focus on ergonomics intervention and quality implementation at a chemical manufacturing plant in Saudi Arabia that is prone to increased number of quality defects and shutdowns. Design/methodology/approach The paper applies the quality improvement through ergonomics (QUITE) methodology as a solution to improve the level of plants quality and reliability. The QUITE implementation relies on a great amount of human participation and constant check of quality results. The study is conducted to solve two main problems in the plant under study, namely, degradation in the products quality and unsolved frequent shutdowns in the production line Findings The study findings suggested to automate the inspection process through “User Alert” system to stimulate the operator attention who triggers a corrective action to avoid any possible process upset of plant shutdown. The implementation increased productivity from 280 to 310 ton; quality conformance from 91.7 to 96.80 per cent; and reduced shutdown from 1.26 days to almost zero downtime. Originality/value The work shed the light on the effect of ergonomics on the quality of finished products. Usually, ergonomics is related to the work environment. However, ergonomics initiatives can spearhead improvement in production quality.