City Research Online

Abstract

Energy needs continue to rise globally, underscoring the importance of reliable and sustainable energy sources such as nuclear energy. A critical aspect of ensuring nuclear reactors meet societal demands is maintaining the structural integrity of Prestressed Concrete Containment Vessels (PCCV). These vessels play a vital role in nuclear safety, particularly in preventing the release of radioactive materials during severe breakdowns. However, the structural health of PCCVs can be compromised by factors like creep, shrinkage, and prestressing system degradation over time.

While previous studies have addressed the seismic response of PCCVs, many have overlooked the long-term effects on material properties, such as concrete shrinkage, creep, and prestress losses. This study addresses this gap by developing a detailed Finite Element model of a conventional PCCV and examining its seismic response at different stages of its design life. By incorporating ageing effects into the analysis, including concrete creep, shrinkage, and prestress losses, this study provides insights into the importance of considering long-term effects in the seismic assessment and design of these critical structures.

The Finite Element model, validated against experimental results reported elsewhere, employs sophisticated constitutive models for concrete and steel, accounting for nonlinear behaviour under seismic loading. Modal analysis techniques were utilized to determine appropriate mesh sizes and evaluate structural response under different boundary conditions, including soil-structure interaction effects.

Furthermore, seismic analyses were conducted using a diverse set of earthquake records, considering both "new" and "aged" PCCVs. Results indicate that ageing effects influence the seismic performance of PCCVs such as leading to increased displacement, drift ratios and higher energy dissipation compared to their new counterparts.

Detailed examinations of stress-strain demand during seismic events reveal the onset of concrete cracking and damage, particularly under tension. However, it's crucial to highlight that despite the observed damage, the containment vessels remained structurally sound, with no occurrence of structural failure or yielding in reinforcements, even in areas where concrete cracking was evident.

Overall, this study highlights the importance of accounting for long-term effects in the seismic design of PCCVs to ensure their structural safety and effectiveness in mitigating the consequences of severe nuclear events. By incorporating ageing effects into numerical models, the structural performance of PCCVs can be better assessed over their design life, and necessary measures to enhance their resilience to extreme events can be implemented.

Publication Type:	Thesis (Doctoral)
Subjects:	G Geography. Anthropology. Recreation > G Geography (General) Q Science > Q Science (General) T Technology > T Technology (General) T Technology > TA Engineering (General). Civil engineering (General)
Departments:	School of Science & Technology > Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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