Nuclear Power Plant Design Analysis Essay
The objective of the design is to provide for the safe and effective operation of the nuclear power plant, minimising the likelihood of accidents and ensuring that their consequences can be reliably mitigated.
The primary means to achieve this is the ‘defence in depth’ approach, consisting in the implementation of consecutive and independent levels of protection. In relation to design, the safety provisions of the ‘defence in depth’ approach include: an adequate design for the site characteristics, multiple physical barriers to the release of radioactivity, and the application of strong safety requirements and proven engineering practices to ensure adequate safety margins and a high reliability of design features that preserve the integrity of these barriers.
This is achieved mainly by the use of technology and materials of high quality, control, surveillance and protection systems, and an appropriate combination of inherent safety features and engineered safety systems. These items must also meet stringent requirements for withstanding internal and external hazards, redundancy and diversity, as appropriate. The ‘defence in depth’ approach also relies on effective management systems.
The safety of the plant needs to be demonstrated throughout all stages of its lifetime, in particular before the loading of the nuclear fuel and the beginning of operation. A comprehensive safety assessment, including a deterministic and probabilistic safety analysis, needs to be carried out to ensure that all safety requirements established for the design are met and are in accordance with relevant national and international codes and standards, laws and regulations.
A Member State’s regulatory framework should also include an independent review and assessment of the design. Mechanisms such as a periodic safety review are necessary to ensure the safety of a plant through its operational life, accounting for design changes and modernisation.
The object of this investigation is to assess the effect of a large commercial airplane crashing perpendicularly on to the surface of a spherical reactor building dome. This investigation is related to a project currently in execution. Practical solutions of the postulated case, which vary in the degree of engineering effort used, are shown. Based on safety consideration the various solutions are discussed from the viewpoint of penetration, cracking and collapse modes of failure, where, primarily, the carrying capacity of the structure under an equivalent statical load is considered. The performed investigations include:
(a) Calculation of the failure load following the yield line theory;
(b) Calculation of the sectional forces using the linear-elastic shell theory and subsequent design by the ultimate strength method;
(c) Calculation of the failure load, establishing of the failure mechanism and distribution of sectional forces using the plastic shell theory;
(d) Calculation using a three-dimensional FEM program with plastic capabilities; this includes the collapse load, the failure mechanism and the distribution of sectional forces.
A discussion of the resultant forces and the configutation of the critical section is given for the various methods used. The evaluation of the carrying capacity of the structure with respect to load is based on energy considerations. It is attempted to compare such results, to evaluate possible simplifications in the used solutions, and to give some recommendations for the practical design and for the development of structural details.