VIENNA, July 14 (Reuters) - Below are the technical cornerstones of the deal that Iran and six world powers announced on Tuesday to curb Tehran's nuclear programme in exchange for sanctions relief.
For the full text of the agreement as posted on the Russian Foreign Ministry's website, please click on: here
In accordance with a framework deal reached in Switzerland in April, Iran agreed to operate around 5,000 IR-1 centrifuges out of 6,100 installed machines for uranium enrichment for 10 years.
This is less than half of its current operating capacity. According to the latest report by the International Atomic Energy Agency (IAEA) from end-May, Iran had around 20,000 installed centrifuges of which it was operating roughly 10,000.
Since an earlier framework deal struck in 2013, Iran has stopped enriching uranium above 5 percent fissile purity - no material of a higher grade than this is normally used in nuclear power plants. It has "downblended" or further processed its 20-percent enriched uranium stockpile.
Western countries see the step from 20-percent to 90-percent purity - the level needed for a bomb - as relatively small.
According to the IAEA's latest report on Iran's nuclear activities, it had a low-enriched uranium (LEU) stockpile of 7,537 kg at end-June. Under the final deal, Iran is required to reduce this stockpile to 300 kg of 3.67-percent fissile purification for 15 years.
The rest of the stockpile will have to be downblended to natural uranium or shipped abroad.
Senior Western diplomats have said that the calculation of breakout times - the amount of time it takes to produce enough nuclear fuel for a single weapon - is flexible. Variables include whether nuclear facilities are assumed to be constantly online and whether the construction of an actual bomb and the conversion of uranium gas into metal are included.
The United States says that with the deal Iran's breakout time will be one year for at least 10 years. French Foreign Minister Laurent Fabius said that after the first decade, breakout time will remain "significant" for the next five years.
According to former IAEA official Olli Heinonen and energy expert Simon Henderson, a nuclear explosive device requires at least 25 kg of 90-percent enriched uranium and an enrichment plant with 5,000 separative work units (SWU) annual capacity. Nuclear experts say the IR-1 centrifuge has a capacity of 0.7-1 SWU per year.
Iran's Supreme Leader Ayatollah Ali Khamenei said last month that freezing Iran's R&D for 10 years was not acceptable.
The deal allows Iran to conduct R&D using its more efficient centrifuge models, such as the IR-4, IR-5, IR-6 and IR-8 for 10 years, without being allowed to accumulate enriched uranium.
Critics of the deal are likely to say that allowing Iran to keep such centrifuges would mean it retains the capacity to speed up its enrichment activities quickly.
For a full list of issues related to PMD see
Although senior diplomats agree that Iran has complied with the 2013 interim deal, it had been stalling for months an investigation - which ran parallel to political talks - by the IAEA into the PMD of its past nuclear activities.
Tehran, which has said the data used in the investigation has been fabricated, made significant concessions on PMD.
Under a roadmap signed with the IAEA alongside the political deal, the agency will issue a final report on PMD by the end of this year. This is one condition for sanctions relief - a point which might be hard to sell in Iran. The head of the IAEA said that such a timeline is realistic if Tehran cooperates.
Iranian officials had publicly rejected international access to military sites. The agency had repeatedly asked for such access to the Parchin military site, where it wants to investigate concerns that Iran has conducted experiments to assess how specific materials react under high pressure as in a nuclear blast.
The so-called snapback mechanism is designed to allay fears that Iran might cease to stick to its part of the deal once sanctions are lifted. Under snapback, punitive sanctions are automatically reintroduced if Iran fails to comply with the deal.
Snapback, however, comes with a delay which can stretch to 65 days under the deal. The mechanism will stay in place for at least 10 years. Opponents of the deal are likely to criticise this time lag.
Heavy water reactors, such as the one Iran had started building at its Arak site, can produce weapons-grade quantities of plutonium. Under the deal, Iran agreed to convert the reactor so that such a "plutonium pathway" to a nuclear bomb is ruled out. The core of the Arak reactor will be filled with concrete so it will cease to be operational.
Iran agreed to implement and then ratify the IAEA's Additional Protocol to its Comprehensive Safeguards Agreement. This will give the agency more intrusive access, but does not allow it to stage inspections anywhere and at anytime as the agency will have to request access in advance.
Iran has also agreed to implement Code 3.1, committing it to telling the IAEA of any plans to build nuclear facilities.
A ban on trade of items that could contribute to Iran's ballistic missile programme will remain for up to eight years. Transfers of certain heavy weapons will be banned for up to five years.
- This factbox was compiled using information from U.S. and French factsheets and the text of the deal posted on the website of the Russian foreign ministry (Compiled by Shadia Nasralla; editing by David Stamp)