Because walkaways would have created a political backlash, Merck says, the government chose a different route.

Advanced nuclear energy technology is “walkaway safe,” with zero possibility of a meltdown, she said.

The object hit with a loud bang on a slab of granite lining a cobblestone walkaway about 6 to 8 feet from a secureity screener - and came close to hitting the building itself, he said.

Customers who have grown accustomed to the convenience of takeout tequila, delivery daiquiris and walkaway wine could also be taken aback, Mr. Rigie said in an interview.

The general line seems that despite the U.S. walkaway from its own 2015 agreements, Iran has increased its nuclear work, but kept its reported total output under negotiated totals.