A planned nuclear cooperation deal between the United States and Saudi Arabia won't include the toughest inspection regime the U.N.'s atomic watchdog has to offer, but it's going to come close on the activities that matter most. That's the picture International Atomic Energy Agency chief Rafael Grossi laid out Monday in Vienna, speaking to reporters during the agency's September Board of Governors meeting. Riyadh isn't signing the IAEA's Additional Protocol, the tool that lets inspectors show up unannounced at sites a country hasn't even declared.…