The United States is confident that Iran has filled the Arak nuclear reactor's core part calandria with concrete to decommission it, US Department of State spokesperson John Kirby told reporters on Thursday, Sputnik reported.
"I know that they have taken those steps with respect to shutting it down and that includes the pouring of concrete," Kirby said. "So, yes, we, believe that concrete has been poured and applied."
On Wednesday, US Secretary of State John Kerry announced Iran had informed the United States it removed the calandria and was going to fill it with concrete in the coming hours.
In July, Iran and the P5+1 group of countries comprising the United States, Russia, China, France and the United Kingdom plus Germany, signed an agreement that guarantees the peaceful nature of Iran's nuclear program in exchange for sanctions' relief.
Under the agreement, Iran is obliged to reduce its stockpile of low-enriched uranium by 98 percent to 300 kilograms (660 pounds), among other measures.
The United States has promised to provide technical support during the Arak reconfiguration project as well as to evaluate and monitor the applied fuel and safety standards.
The United Kingdom, France and Germany will inspect the work and safety standards, and will supply the necessary equipment. Russia will provide advice, and, if necessary, will inspect the modernized rector.