The outer steel dome of the nuclear island containment building of unit ... The Sanmen and Haiyang plants are already home to two AP1000 units each. Unit 1 of the Haiyang plant entered commercial ...

Adding steel rings will help support the dome -- but it will cost a fortune! Tension rings made of steel act like hoops on a barrel and prevent the arches in a dome from thrusting outward.

If you build a very tall, solid steel dome, the heavy weight of the structure will push the walls outward, creating a force called tension. This may cause the dome to crack and collapse!