The Iran Nuclear Deal: The Forest and the Trees

, physicist & co-director, Global Security | August 5, 2015, 11:45 am EDT
Bookmark and Share

We’ve all seen the stories about the Iran nuclear deal, which was concluded on July 14 between Iran, Britain, China, France, Russia, Germany, the United States and the European Union. What does it really mean for U.S. and global security?

First, the forest:

The Iran nuclear deal is a good thing. The Joint Comprehensive Plan of Action (JCPOA), as it is officially titled, will make it more difficult for Iran to produce the fissile material needed to make a nuclear weapon, should it decide to do so.

And if Iran did decide to pursue a nuclear weapon, the deal will make it more likely that the world will have warning and the warning time will be longer than it would without a deal, providing more time for the  international community to respond.

Thus, the deal is an important step forward in curbing Iran’s ability to produce a nuclear weapon.

(Source: US Dept of State)

(Source: US Dept of State)

Nuclear power and nuclear weapons

Let’s take a step further back. At the core of this issue is a problem inherent to nuclear power: some types of civil nuclear facilities can also be used to produce fissile material for nuclear weapons. In particular, almost all power reactors worldwide use uranium fuel that has been “enriched” to increase the concentration of the isotope U-235 above that in uranium found in nature. Natural uranium ore contains less than 1% U-235, and reactor fuel typically contains 3 to 5% U-235. Nuclear weapons typically use uranium that has been enriched to 90% or greater, but enrichment facilities producing low-enriched uranium (LEU) for fuel can be operated to produce weapons-grade highly enriched uranium (HEU) instead.

Reactors fueled with uranium produce plutonium as they use the fuel. Some countries have reprocessing facilities that extract the plutonium from spent fuel, and this plutonium can be used to build nuclear weapons as well as to fuel reactors.

The Nuclear Non-Proliferation Treaty (NPT) gives its signatories the right to develop nuclear power, including enrichment and reprocessing facilities. The International Atomic Energy Agency (IAEA) is charged with both facilitating nuclear power programs in these countries and carrying out inspections to verify that their facilities are not used to produce fissile material for weapons.

However, any country that possesses enrichment or reprocessing facilities will have the latent ability to produce fissile material for nuclear weapons. In other words, a country could throw out the IAEA inspectors and use these facilities for weapons purposes. The time needed to produce enough material for a nuclear weapon—the “breakout time”—will depend on the type and size of the facilities. But ultimately, the real barrier to a weapons program is not technical, but political.

The history of Iran’s nuclear program

The United States provided Iran with its first research reactor in 1967 as part of its “Atoms for Peace” program. The Shah had plans to build some two dozen nuclear power plants, and a German company was building Iran’s first two reactors at Bushehr when construction was halted by the Iranian revolution in 1979. One of the reactors was later completed by a Russian contractor, and began operating in 2011. Russia has a contract to provide fuel for the Bushehr reactor, and Iran will return the spent fuel to Russia.

Iran signed the NPT on the day it opened for signature in 1968, obligating it to not produce or acquire nuclear weapons. Accordingly, the IAEA applies “safeguards” to Iran’s nuclear facilities to verify that they are not being used for nuclear weapons purposes.

In 1997, the IAEA developed an “Additional Protocol” that NPT signatories can voluntarily adopt. The protocol requires the signatory state to provide additional information about its nuclear activities to the IAEA and allows the agency to conduct inspections at any facilities or sites that it suspects may be engaged in undeclared nuclear activities. The majority of NPT states have adopted the Additional Protocol, but Iran has not.

In 2002, an Iranian dissident group publicly revealed that Iran had two nuclear facilities under construction that it had not informed the IAEA about: a uranium enrichment facility in Natanz and a heavy water production facility in Arak. The latter would provide heavy water for the planned research reactor in Arak. U.S. and other intelligence agencies almost certainly knew about these facilities before their existence was made public.

At the time Iran was only required to inform the IAEA about these facilities six months before nuclear material was introduced into them, which had not yet happened, so it was still in compliance with its safeguards obligations. Nonetheless, these revelations put into motion a series of negotiations between Iran, the IAEA, and various European nations. As a result, in 2003 Iran agreed to inform the IAEA of any nuclear facilities as soon as it decided to build them. Iran also signed the Additional Protocol. However, it did not ratify the agreement, and suspended it in 2006, although it has continued to allow the IAEA to conduct its regular safeguards inspections.

The IAEA found that Iran had failed to report numerous nuclear-related activities, and in 2006 reported to the UN Security Council that Iran was not in compliance with its safeguards agreement. Shortly thereafter, the Security Council demanded that Iran suspend all enrichment activities and then imposed sanctions on Iran after it refused to do so.

In 2011, the IAEA also reported that it had evidence that Iran had conducted non-nuclear experiments relevant to designing nuclear weapons until 2003. In particular, the agency believes that Iran had conducted research on the high explosives needed to kick off a nuclear explosion at its Parchin military base.

Details of the Iran nuclear deal

Now for the trees:

Under the terms of the nuclear deal, Iran will accept significant constraints on its nuclear program for the next 10 to 15 years (recall that the NPT places no restraints on the peaceful nuclear programs of its signatories). It will sign and implement the Additional Protocol, the provisions of which will extend indefinitely. It will also allow IAEA monitoring and inspections beyond those required by the protocol for the next 15 to 25 years.

There are several potential pathways for Iran to produce the fissile material needed for a bomb—it could enrich uranium using known facilities, produce plutonium using known facilities, or operate covert facilities. The deal constrains those pathways for the next 10 to 15 years.

Iran has uranium enrichment facilities at Fordow and Natanz, with a total of some 19,000 centrifuges. Under the deal, Iran will disassemble and store roughly 13,000 centrifuges. It will not enrich uranium at Fordow, but will maintain 1,000 centrifuges at that facility, some of which will be used to produce stable isotopes for research or commercial purposes with the remaining kept idle. It will continue to enrich uranium at Natanz, but only using about 5,000 of its first-generation IR-1 centrifuges, and only to an enrichment level of 3.67 percent.

But perhaps most significantly, Iran will reduce its current stockpile of about 10,000 kg of low-enriched uranium (LEU) to 300 kg of 3.67 percent LEU for 15 years. It is much easier to produce weapon-grade uranium if you start with 3.67 percent LEU rather than natural uranium—by about a factor of three. By essentially eliminating Iran’s stockpile of LEU, the deal extends the time it would take Iran to produce enough material for a weapon.

How long would it take for Iran to acquire enough HEU to build a bomb, if it decided to leave the NPT and threw the inspectors out?

There is no precise answer to this question, because it depends on a host of factors that are not precisely known—such as the amount of HEU required for Iran’s bomb design, the performance of its centrifuges, and how quickly Iran could reinstall the centrifuges that will be disassembled and in storage under the terms of the deal. The administration states that currently, it would take Iran 2-3 months, and that under the agreement the “breakout time” would increase to a year. A breakout time of roughly a year is consistent with the following reasonable assumptions: (1) a nuclear weapon would require roughly 28 kg of weapons-grade HEU (90% enriched), which is the standard IAEA assumption; (2) the average capacity of Iran’s IR-1 centrifuges is about 0.75 SWU/year, as indicated by the latest data from Iran’s May 2105 report to the IAEA; and (3) Iran would use all 6,000 installed IR-1 centrifuges at Natanz and Fordow, but could not reinstall the 13,000 disassembled centrifuges within a year.

While the breakout time would vary somewhat depending on the details, it will be significantly longer under the deal than it is today.

What if Iran decided to instead follow a plutonium route to a bomb? Iran could produce plutonium at its Arak research reactor, now under construction. While all reactors fueled with uranium produce plutonium, some types of reactors produce it at a higher rate than others. As initially configured, the Arak reactor would produce enough plutonium in its spent fuel for roughly one nuclear weapon each year. However, the spent fuel would need to be reprocessed to extract the plutonium, and Iran has no reprocessing facility.

Under the agreement, Iran will destroy the existing reactor core, and replace it with one of a new design, which would require ten years to produce enough plutonium for one nuclear weapon. Iran will ship all spent fuel out of the country for the lifetime of the reactor.

Moreover, under the deal Iran has agreed to not reprocess or engage in reprocessing R&D for 15 years, and states that it does not intend to do so after that.

Finally, what if Iran tried to build a covert enrichment or reprocessing facility? Under the agreement, the IAEA will monitor all uranium ore mined in Iran or imported, cutting off Iran’s ability to supply uranium to any covert enrichment facility. In addition, Iran would not be able to surreptitiously acquire spent fuel to reprocess since its reactors will be monitored.

Moreover, under the agreement, the IAEA has the right to inspect any site where it suspects Iran is engaged in prohibited activities. An inspection must take place within 24 days from the time of the request, and any work with fissile material would leave a detectable trace.

Where to go from here?

The agreement puts strong, verifiable restrictions on Iran’s nuclear program, and the U.S. Congress should endorse it.

In addition, the United States and other countries can do more to widen the gap between nuclear power and nuclear weapons—in Iran and elsewhere.

The United States does not reprocess its spent fuel, and this policy has helped constrain reprocessing by other countries. The United States should continue to work to persuade other nations to forgo reprocessing.

As several researchers at Princeton—Alexander Glaser, Zia Mian and Frank von Hippel—advocate in an article in Science, the parties to the Iran agreement should invest in Iran’s enrichment facility so that it becomes multinational. And the United States should abandon its plan for a new national enrichment facility, instead continuing to rely on Urenco, a company owned by Britain, Germany and the Netherlands. A U.S. commitment to multinational enrichment would help create a regime in which all enrichment facilities were multinational and, as the Princeton group put it, “in which nuclear power rules apply equally to all states.”

Posted in: Nuclear Weapons Tags: , , ,

Support from UCS members make work like this possible. Will you join us? Help UCS advance independent science for a healthy environment and a safer world.

Show Comments

Comment Policy

UCS welcomes comments that foster civil conversation and debate. To help maintain a healthy, respectful discussion, please focus comments on the issues, topics, and facts at hand, and refrain from personal attacks. Posts that are commercial, self-promotional, obscene, rude, or disruptive will be removed.

Please note that comments are open for two weeks following each blog post. UCS respects your privacy and will not display, lend, or sell your email address for any reason.

  • Joe Cleetus

    Dear Dr. Gronlund,

    Thank you for this article.

    I see you and David Wright of the UCS have signed the letter by 29 scientists to President Obama, dated Aug 8, 2015. Top nuclear weapons consultants and Nobel prize winners in Physics, among others, have laid out the cogent reasons why this deal is indeed a good accord that can form the basis of a peaceful long-term resolution of the nuclear question with Iran, with adequate safeguards.

    In his American U speech President Obama concluded by saying

    “Contact your representatives in Congress”

    Here’s an easy way, using a method provided by the Council for a Livable World, founded by Leo Szilard, the scientist who urged Einstein to write that fateful letter to Pres Roosevelt. If you enter your zip code a support letter for the Iran agreement will automatically go as e-mail to the two senators and congressperson who represents your district, or you can call on the phone:

    Call your member of Congress on the phone:


    Send an e-mail to your member of Congress:

  • Alene S. Ammond, Former NJ Sta

    re: Iran’s hate of Israel. Their ultimate goal is to bomb Israel off the face of the earth.
    That has been stated many times. And has anyone forgotten how they treat their
    women? Not confined to Iran, but the issue of how women are treated is a major
    problem in many radical Muslim countries. Last year in Middletown, N.J. I was
    asked to attend and speak at a meeting related to the Middletown, Planning Board
    public hearing about enlargement of a Mosque. About 700 Middletown citizens
    attended. The wives of the Muslim men were not permitted to speak or sit with them.
    All American public hearings on any issue are specifically set for the public to speak
    out on various issues/laws, etc. When I attempted to speak the Imam and his Atty
    refused to relinquish the table on which the microphone was attached. I was forced
    to insist that they get up so that I could speak. They did, but further protested my
    right to speak.

    The United States has always been the country taking refugees from other nations
    who came here to find freedom, jobs and religious freedom. Radical Muslim behavior
    does not tolerate female independence, I am referring to “radical” behavior.

    At another meeting in Jersey City, NJ young Palestinians took over a meeting
    there putting up Hamas signs, etc.

    Anyone believing they can have faith in Iran’s ability not to attack their perceived
    enemies, i.e. Israel over the longer haul is living in a dream world. Just as our
    President destroyed our economy, he will also weaken our strategic defenses.
    I will address the deliberate weakening of our armed forces in another article.
    Alene S. Ammond, Frmr NJ State Senator

  • Alene S. Ammond, Former NJ Sta

    A treaty with Iran is a fools errand. Iran will never fully adhere to any conditions
    placing their nuclear ambitions on “hold.” While it is true that our efforts to contain
    them have placed Iranian leaders in a tough spot fiscally, that part of U.S. efforts
    worked. However, Iran’s leaders have no intention of ultimately abiding by
    any restrictions on their nuclear ambitions. They shall seek a way to broaden
    their nuclear capabilities in other ways. President Obama is using this Treaty
    to bolster his anti war image. However, over the long term, Iran will not abide
    by such restrictions. As soon as their economy is improved they will pursue
    their most cherished goal…..”to bomb Israel off the face of the earth.”

    Given President Obama’s mishandling of our economy among other issues,
    this Treaty will prove dangerous to the United States as well as our Allies
    and most of all Israel. Alene S. Ammond, Frmr NJ State Senator

    • janipurr

      Have you always had the gift of prophecy? FFS, if what you say is true, why doesn’t Iran have a functional nuclear weapon *already*? They have certainly had the time and ability to make one.

    • Alene S. Ammond, Former NJ Sta

      Actually, they did not. have the ability to create a nuclear weapon. That is a
      critical process which demands essential elements to make one. The History
      of Iran’s behavior over the years has not been a good one. They were
      responsible for the bomb that killed 19 U.S.Airmen, wounding 505 servicemen
      and women, including Saudi civilians at Dhahran, Saudi Arabia. I know
      their history. President Obama wants to end his Presidency with what he
      sees as a huge win. However, he has a bad record when it comes to
      understanding the Middle East/ did not help Israel’s Netanyahu and
      treated him like the enemy; That was a first in U.S. History. Iran
      cannot be trusted and will ultimately use this time to bld. their
      weapon. Then watch out Israel and the United States. Obama’s
      mishandling of our economy has tanked it and now he is mishandling
      the most serious problem of all: Iran.

      • Brian Powers

        Also Does anyone really think Iran is suicidal and that they will risk the incineration annihilation of their people and society?
        JUST ONE U.S. Navy ballistic missile submarine carries 24 × Trident II D5 SLBM with up to 12 MIRVed W76 or W88 (300–475 ktTNT) nuclear warheads each, range 6,100 nmi (11,300 km; 7,000 mi)
        So that’s 288 warheads with burst temperatures over 50,000° – From an Indian Ocean launch to detonation over Iran approximately 12 minutes.. And we have 24 of the submarines. And 10,000 other warheads deliverable via other platforms.