An excellent summary of how the agreement works:
http://www.slate.com/articles/news_...ce_constrain_the_islamic_republic.single.html
"The timing of sanctions-relief is addressed in Annex V of the document, and it’s very clear that nothing gets lifted right away. This is a step-by-step process.
The first step is “Adoption Day,” which occurs 90 days after the deal is endorsed by the U.N. Security Council. On that day, the United States and the European Union start taking legal steps to lift certain sanctions—while Iran must pass the Additional Protocol of the Nuclear Non-Proliferation Treaty (which allows for onsite inspection by the International Atomic Energy Agency) and issue a statement on “Past and Present Issues of Concern,” acknowledging or explaining military aspects of its nuclear program in the past. (Many critics were certain that Iran would never own up to this obligation.)
The second step is “Implementation Day.” This is when the West really starts to lift sanctions, but only “upon the IAEA-verified implementation by Iran of the nuclear-related measures”—that is, only after international inspectors are satisfied that Iran has fulfilled its main responsibilities in freezing and reducing elements of its nuclear program. Section 15 of Annex V lists 11 specific requirements that Iran must have fulfilled, including converting the Arak heavy-water research reactor, so it can no longer produce plutonium; reducing the number of centrifuges and halting production of advanced centrifuges; slashing its uranium stocks; and completing all “transparency measures” to let the inspectors do their job.
The third step is “Transition Day,” when more sanctions are dropped. This happens eight years after Adoption Day, and even then only after the IAEA Board of Governors issues a report, concluding “that all nuclear material in Iran remains in peaceful activities.”
Finally, there is “UNSCR [U.N. Security Council Resolution] Termination Day,” when the Security Council drops all of its remaining nuclear-related sanctions. This happens 10 years after Adoption Day.
In other words, sanctions are not lifted upon the signing of the deal or anytime at all soon—and when they are lifted, it’s only after inspectors signify that Iran is abiding by the terms of the deal, not simply that a certain date on the calendar has passed.
But how will the inspectors know this? The Advanced Protocol of the Non-Proliferation Treaty, which Iran must sign and ratify soon, allows international inspectors inside known nuclear sites. But what about covert sites? This has always been a knotty issue in arms control talks. No country would sign an accord that lets outsiders inspect any military site of their choosing simply because they “suspect” covert nuclear activity might be going on there. And yet covert nuclear activity might be going on somewhere. How to reconcile this genuine dilemma?
The deal’s section on “Access,” beginning with Article 74, lays out the protocols. If the inspectors suspect that nuclear activities are going on at undeclared sites, they will request access, laying out the reasons for their concerns. If access is denied, the matter can be turned over to a joint commission, consisting of delegates from the countries that negotiated the deal, which would have to rule on the request—either by consensus or majority vote—within seven days.
This may seem legalistic to some, but what are the alternatives? Meanwhile, under other articles of the deal, the inspectors will have access to the complete “supply chain” of Iran’s nuclear materials—from the production of centrifuges to the stockpile of uranium to such esoterica as all work on neutrons, uranium metallurgy, and multipoint detonation optics. For instance, centrifuge rotor tubes and bellows will be kept under surveillance for 20 years.
The point is, cheating—pursuing an atomic weapon covertly—requires a number of steps, at a number of complexes, some of which are very likely to be detected, given the IAEA’s rights of surveillance. If Iran suddenly denies IAEA those rights, if it ignores a decision by the joint commission, the United States and the European Union can pull out of the deal and reinstate the sanctions."