Two of the nine massive 440-ton parts used for the ITER fusion reactor are defective according to French nuclear regulator. The regulator has refused to accept the project director's proposed workaround. The parts are not returnable and did not come with a warranty. $65 billion and the future of the world's largest fusion reactor is at stake.

I’m surprised the segments were designed so they cannot be removed and replaced in future.

they must be welded together with mm precision to achieve the required radiation protection.