Did you read your link? Honest question.

Here is a quote:

    A concrete dome containing radioactive waste on the
    Marshall Islands is cracking open, The Washington 
    Post reported Monday.

    The U.S. conducted 67 nuclear tests in the Marshall
    Islands in the 1940s and 1950. The dome was built decades     later to cover remaining fallout debris

To put it in perspective, that's like closing solar power plant, because a star went supernova in another galaxy.