Greece will beef up ports, airports and border crossings with dozens of U.S.-supplied portable radiation detectors as part of security preparations for this summer’s Athens Olympics, officials said on Tuesday. Greece is hosting the first summer Games since the Sept. 11, 2001, attacks in the United States and has put together the largest security plan in Olympic history, costing some $1.21 billion. A series of minor bombing attacks over the past weeks, which the Greek government called “isolated domestic events,” has raised security concerns for the hosts and countries planning to send their teams to the Games. Full Story