Complex geometry element of researach reactor

Dear Experts,

I am currently modeling a research reactor, VVR-SM, and have completed most of the work. However, I am facing a challenge in accurately modeling the support element located above the fuel assembly. This element is 1 cm thick and is positioned directly on top of the fuel assembly.

To clarify the issue, I have attached a comparison image showing my current model and how the support element should look in the final design. I would greatly appreciate your guidance and hints on how to improve this part of the model.

Thank you for your time and assistance!