Finite Element Model Description

In the analysis of the structure, a three-dimensional non-linear transient fluid-structure shock wave analysis is carried out to assess the structural integrity of the reinforced structure following a postulated handling accident. In Figure 1, the schematic representation of the structure of intent and part of the surrounding structures are shown. Given the localized nature of the drop scenario considered, only part of the water in the adjacent structure is included in the assessment as shown in Figure 1. Since the main storage is not directly connected to the pool, it is modelled using rigid shell elements. To ensure that the main storage contribution to the lateral stability and rigidity of the adjacent pool is minimized, the channel that connects the main storage to the pool is modelled in a manner that will minimize the transfer of load to the pool. The discretised components of the full model are shown Figure 1. The embedded reinforcing bars are explicitly modelled considering their respective diameters. The reinforcing bar topology is shown in Figure 5.

Given the complexity of the model, a variety of element types are used for each of the structural components and are listed in Table 1. In addition to the non-linear structural components, the water transmitting the shock wave within the containing structure is modelled using a hydrodynamic finite element formulation. The fluid-structure interaction is accommodated using a large deformation contact/sliding surface algorithm applied to all fluid-structure boundaries. At the boundary interfaces of the main storage structure and fluid, silent (i. e., non-reflective) viscous elements are utilized. This prevents artificial wave reflections due to modelling constraints by permitting incident waves to travel through the boundary to the portion not included in the model.

Figure 5: Steel Reinforcement in Wet Cask Handling Bay

Table 1 Details of Simulation Model Topology

Model Details

Component

Element Type

Number of Elements

Concrete

3D Continuum

86,408

Rebar

3D Beam

132,422

S. S. Steel Liner

3D Shell

7,138

Inspection Platform

3D Shell

4,648

Inspection Platform

3D Beam

5,712

Water

3D Continuum (Hydrodynamic)

133,456

Container

3D Continuum (Rigid)

252

Bottom of the main storage and pool

3D Shell

2,572

Contact Pairs

Contact

6

Total Number of Elements

372,614

Total Number of Nodal Points

254,576