Iran has filled a contentious nuclear reactor core with concrete

Iran has removed the core of its Arak heavy water nuclear reactor and filled it with cement, an informed source told the Fars news agency on Monday.

The fate of the reactor in central Iran was one of the toughest sticking points in the long nuclear negotiations that led to a agreement in July.

Removing the core of the heavy water reactor to produce less plutonium is a crucial step before relief from economic sanctions agreed under the deal can start.

Under the terms of deal, Iran accepted the Arak heavy water reactor to be reconfigured so it cannot yield fissile plutonium usable in a nuclear bomb.

China, United States, France, Britain, Russia and Germany have agreed to participate in the redesign and the construction of the modernized reactor.

The Islamic Republic has said that the 40-megawatt, heavy-water plant is aimed at producing isotopes for cancer and other medical treatments, and has denied that any of its nuclear activity is geared at developing weapons.

The removal of core of Arak reactor will be one of the final steps that Iran must take for implementation of the nuclear deal, known as Joint Comprehensive Plan of Action (JCPOA).

Behrouz Kamalvandi, the spokesperson for Iran's atomic energy agency, said in an interview the Iranian Etemad newspaper published on Monday that "Iran has met its commitments under the July nuclear agreement earlier than expected".

"Implementation of JCPOA will finish in the next 7 days," he added.

Iranian President Hassan Rouhani said in a speech broadcast live on state television on Monday: "We are hopeful that the sanctions against Iran would be lifted in the next few days."

US Secretary of State John Kerry has also said that the last steps in the Iran nuclear deal could be "days away" and that sanctions could be lifted before the end of the month. But before the sanctions can be lifted, inspectors need to conclusively determine that Iran has cut off potential routes to it constructing a nuclear weapon.

That means, according to The Hill, that as per the nuclear deal, Iran must dismantle thousands of centrifuges and also drastically reduce its uranium stockpile. Once those conditions are met and Iran has abided by its portion of the nuclear deal, then the US will lift sanctions on the country.

The US would also unfreeze an estimated $100 billion in Iranian oil money that is currently in overseas banks.

Although Iran is seemingly following the outline of the nuclear deal, Democrats and Republicans are calling on the US to place further sanctions on Tehran in response to ballistic missile testing in the fall. The call for sanctions is coming from both supporters and detractors of the nuclear deal and they say that it is crucial for the US to carry out the sanctions so as to maintain credibility.

Iran, The Wall Street Journal notes, is barred from developing ballistic-missile systems under a UN Security Council resolution. The White House, though, has shown no willingness to enforce new additional sanctions again Iran.

(Reuters reporting by Bozorgmehr Sharafedin)