I built my home in the 1990’s and used poured concrete with a welded faraday cage in the concrete as protection cage. Even poured my first floor 12 ft up with rebar, mesh and steel bar joist with 6 inches of concrete. Took me two days just to weld the rebar crossing joints for the Faraday cage. It was my first overhead poor and at 2000 square feet, I could feel it wobble when I ran the power trowel. If it would have collapsed it would have killed me.
The basement walls are 12 inches thick, 12 ft high , in ground, with rebar on the snap ties welded to vertical rebar that is welded to the floor rebar cage.
I had my vision of the coming solar storms in the early 1990’s and built my house on the farm accordingly.
Sound like you have a bunker!
Like we said in basic training, grounded to inspection side.