Nuclear security summit to focus on dirty bomb scenario

When it comes to nuclear attacks, there is no shortage of nightmare scenarios. Saboteurs could breach a nuclear power station and start a reactor meltdown. A renegade Pakistani general could seize tactical nuclear weapons and blow up a city. Radioactive materials, which are found in many hospitals, could cause dirty bomb mayhem at an airport. Against this backdrop, US President Barack Obama will host world leaders for a Nuclear Security Summit on Thursday, in an international effort to stop possible assailants from using radioactive material to outdo the 9/11 attacks on New York and Washington. The leaders may not be doing enough. Analysts point to big gaps in the global security...