Seismic Isolation Assemblies for Nuclear Reactor Vessels
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Solution Overview
Problem
Nuclear reactor systems face challenges in managing dynamic and seismic forces, which can lead to stress on connections and potential damage to the reactor core and fuel elements during seismic events, compromising the integrity of the system and risking radioactive material release.
Innovation Solution
The implementation of seismic isolation assemblies with plastically deformable elements and hydraulic damping features that absorb seismic energy through plastic deformation and friction, reducing the transmission of dynamic forces to the reactor module and maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If seismic isolation hardware is positioned between substructure and superstructure to minimize dynamic response, then in-structure accelerations and forces are reduced, but device complexity increases
Solution Approach 1:
The seismic isolation system is divided into multiple independent isolators distributed at various levels (base isolators between foundation and containment building, intermediate isolators between containment building and reactor module). This segmentation allows each isolator to handle specific portions of seismic forces, reducing the complexity burden on any single component while collectively minimizing in-structure accelerations and forces.
2Stability of the object's composition
If multiple intervening structures are used to support the reactor module, then structural stability is improved, but seismic force amplification increases
Solution Approach 1:
Seismic isolators are introduced as intermediary elements between the ground/support surface and the reactor module, and between intermediate structures and the reactor module. These intermediaries decouple the seismic force transmission path, allowing the reactor module to remain stable on multiple supports while preventing force amplification by absorbing and dissipating seismic energy at each isolation level.
3Reliability
If connections are made rigid to maintain integrity during seismic events, then structural integrity is improved, but stress on connections during earthquakes increases
Solution Approach 1:
The connection characteristics are changed from rigid to flexible through the introduction of seismic isolators. These isolators provide the necessary flexibility to accommodate seismic movements while maintaining connection integrity through controlled deformation mechanisms (elastomeric materials, friction dampers, or yielding elements). This parameter change reduces stress on connections during earthquakes while preserving reliability through maintained structural continuity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively attenuates seismic forces, reducing the risk of damage to the reactor core and fuel elements, maintaining system integrity, and minimizing maintenance costs by allowing for non-destructive operation during seismic events.
Implementation Method 1
seismic isolation assemblies with plastically deformable elements and hydraulic damping features that absorb seismic energy through plastic deformation and friction
Implementation Method 2
seismic isolation assemblies with plastically deformable elements and hydraulic damping features that absorb seismic energy through plastic deformation and friction
Data Source
AI summary
A system for attenuating seismic forces includes a reactor pressure vessel containing nuclear fuel and a containment vessel that houses the reactor pressure vessel. Both the reactor pressure vessel and the containment vessel include a bottom head. Additionally, the system includes a base support to contact a support surface on which the containment vessel is positioned in a substantially vertical orientation. An attenuation device is located between the bottom head of the reactor pressure vessel and the bottom head of the containment vessel. Seismic forces that travel from the base support to the reactor pressure vessel via the containment vessel are attenuated by the attenuation device in a direction that is substantially lateral to the vertical orientation of the containment vessel.