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Iran's Nuclear Activities
Dr. Frank Barnaby, November 2004

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The major powers - particularly, Europe, Japan, Russia and the USA - suspect that Iran is clandestinely developing nuclear weapons. Firm evidence for this suspicion comes mainly from the International Atomic Energy Agency (IAEA). Nuclear-weapon activities in Iran are not new - in fact, they date back to the days of the Shah who had ambitions to acquire a nuclear force. But today's Iranian government insists that its nuclear activities are solely related to its civil nuclear programme and that it is not developing nuclear weapons.

The IAEA has announced that Iran is building two plants at Natanz to enrich uranium and is constructing a heavy-water reactor in Arak. The Iranian government has acknowledged the existence of these two previously secret facilities but claims they are part of its civil nuclear programme and not part of a military nuclear-weapon programme. The Iranian government, however, admitted to these activities only after the National Council of Resistance, an Iranian opposition group, announced that they were underway.

Both of the uranium enrichment and the heavy water production plants raise concerns. A heavy-water reactor is a particularly efficient way of producing plutonium for use in nuclear weapons. A uranium enrichment plant can produce the highly enriched uranium needed for nuclear weapons.

Many argue that because Iran has enormous reserves of oil and gas it does not need nuclear energy and that its nuclear programme demonstrates ambitions to produce nuclear weapons. Iran claims that it needs to export as much of its oil as possible to earn much needed foreign currency, that its oil reserves are finite and that nuclear power is a sensible investment for the future.

Iranian Nuclear Activities

Apart from the heavy water and uranium enrichment plants, there are other Iranian nuclear activities that raise suspicions. These include:

  • the development of uranium mines;

  • the construction of a uranium conversion facility at the Esfahan Nuclear Technology Centre (ENTC) to convert uranium ore (yellow cake) into uranium hexafluoride gas, suitable for use in gas centrifuges for the enrichment of uranium; and

  • the operation of a laser enrichment facility.

The IAEA has also discovered that Iran has in the past:

  • imported uranium hexafluoride gas to test gas centrifuges at the Kalaye Electric Company, thereby producing some enriched uranium;

  • imported uranium metal for use in laser enrichment;

  • produced uranium dioxide, uranium hexafluoride, and a number of other uranium compounds using imported uranium dioxide; and

  • produced uranium dioxide targets at ENTC and irradiated them in the Tehran Research Reactor (TRR). The targets were then processed in hot cells to separate the plutonium.

Iran violated its Safeguards Agreement with the IAEA, required by the Non-Proliferation Treaty (NPT), by failing to report many of these activities to the Agency as the Safeguards Agreement requires. Disclosures by Iran of its nuclear programme show that it had concealed many of its nuclear activities, and consequently violated its obligations under the Safeguards Agreement and the NPT.

Iran has signed an Additional Protocol to its Safeguards Agreement with the IAEA but the Iranian parliament (the Majlis) has not yet ratified it. The Additional Protocol permits the IAEA improved access to Iran's nuclear facilities, including the collection of environmental samples.

These violations are the basis of the international suspicions that Iran is secretly developing nuclear weapons. None of these activities are in themselves illegal; it is the failure to report them to the IAEA that is illegal.

Because of its long experience in nuclear physics and engineering and because it has been operating nuclear research reactors for decades, Iran has a cadre of trained personnel that could be switched to a nuclear-weapon programme. If it produces the fissile material - highly-enriched uranium or plutonium - needed for nuclear weapons it could fabricate them in a relatively short time.

Iran's Current Nuclear Activities

It is common knowledge that Iran has a civilian nuclear-power reactor under construction. The Russians are building the 1,000 megawatt-electrical light-water reactor at Bushehr. It will use low enriched (about 3.5 percent in uranium-235) as fuel. Under the contract Iran has with Russia, Russia will provide the fuel for the lifetime of the reactor and will take back to Russia the spent fuel for storage and possibly reprocessing.

This power reactor is, according to Iran, the first of a series of power reactors planned to generate 6,000 megawatts of electricity. Iran explains that it is interested in establishing a capability to produce low-enriched uranium so that it has an indigenous supply of nuclear reactor fuel.

Iran operates four research reactors, three at the Estahan Nuclear Technology Centre and one at the Nuclear Research Centre in Teheran. Two, at Estahan, are sub-critical assemblies used for training nuclear physicists and technicians; they have both been operating since 1992. The third at Estahan is a 30-kilowatt research reactor used for research purposes; it has been operating since 1994. The fourth is a 5 megawatt-thermal reactor also used for research; it has been operating since 1967, an indication of the length of time during which Iran has been interested in nuclear technology.

The two facilities suspected of being part of a nuclear-weapon programme are: a plant to produce heavy water, located near the town of Arak, about 250 kilometres from Teheran; and two gas centrifuge plants under construction at Natanz, 40 kilometres from Kashan. One is a Pilot Fuel Enrichment Plant (PFEP) and the other is a large commercial-scale Fuel Enrichment Plant (FEP). Iran has acknowledged that components for gas centrifuges have been produced in the workshop of the Kalaye Electric Company in Tehran.

PFEP will apparently contain about 1,000 centrifuges and may already be completed. Iran plans to install more than 50,000 centrifuges at the commercial scale FEP; installation of centrifuges is scheduled to start in early 2005.

Uranium hexafluoride gas was introduced into the first centrifuge at PFEP in June 2003 to test a single centrifuge. In August 2003, Iran began testing a ten-centrifuge cascade with uranium hexafluoride gas.

Heavy water production

Heavy water (water in which the hydrogen is the deuterium isotope) is an excellent moderator and coolant for a reactor fuelled with natural uranium. Such a reactor is excellent for the production of plutonium of a grade suitable for use in very effective nuclear weapons (so-called weapon-grade plutonium). The Dimona reactor used by Israel to produce plutonium for its nuclear weapons is a heavy water-natural uranium reactor, as is the Cirus reactor used by India produce plutonium for its nuclear weapons.

Heavy water and enriched uranium can both be used in a civil nuclear-energy programme; they are dual-purpose materials. For example, the Candu-type nuclear-power reactor developed and used by Canada uses heavy water and a gas-centrifuge plant can produce the low-enriched uranium needed to fuel civil nuclear power reactors.

Iran claims that it wants to replace the aged (35-year old) Tehran Research Reactor and plans to do so by building a new heavy water reactor, called the IR-40, at Arak. The IR-40 will be a 40-megawatt (thermal) reactor cooled with heavy water. According to the IAEA, Iran plans to manufacture the fuel (uranium dioxide) elements for the IR-40 in the Fuel Manufacturing Plant (FMP) to be built at the Esfahan establishment. Iran says that the purpose of the IR-40 reactor is the production of radioactive isotopes for medical and industrial uses.

Iran says that about 85 tonnes of heavy water will be initially required for IR-40 and less than 1 tonne will be need annually. Iran is constructing a heavy water plant at Khondab near Arak with an initial capacity of 8 tonnes of heavy water per year. Apparently, a second production with a similar production capacity is under construction.

Uranium enrichment using gas centrifuges

The production of heavy water on a reasonable scale is a much easier task than producing significant amounts of highly enriched uranium in a gas centrifuge plant. The capacity of a gas centrifuge is measures in separative work units (SWUs). A reasonable estimate is that each centrifuge of the type that Iran is likely to produce (most likely made from carbon fibre) would have a capacity of about 2.5 SWU per year. That this is likely is indicated by the example of Iraq. In 1991, Iraq had a prototype centrifuge with a carbon-fibre rotor spun at up to 60,000 rpm (a wall speed of roughly 450 meters per second). The enrichment capacity during the best test run reached 1.9 SWU per year. IAEA inspectors estimated that an output of 2.7 SWU per year could have eventually been achieved.

An Iranian facility containing, say, 3,000 centrifuges could produce 7,500 SWU per year or about 40 kilograms of highly enriched uranium per year. It would take this facility at least 5 years to produce enough highly enriched uranium for the nuclear force of six nuclear weapons. With sufficient expertise in HEU-based nuclear weapons, 40kg per year could provide two nuclear weapons.

Assuming that about 60 per cent of the centrifuges have to be rejected as sub-standard, a reasonable assumption, Iran would need to produce about 5,000 centrifuges for the facility. Moreover, gas centrifuges break down frequently because of the mechanical stresses they are under. A steady supply of replacement machines must, therefore, be produced.

A facility operating a cascade of 3,000 centrifuges would use as much energy, electrical power, as a largish city - approximately 200 kilowatt-hours per SWU or roughly 1,000 kilowatt-hours per gram of highly enriched uranium. It would, therefore, be impossible to operate such a facility clandestinely. Building and operating effectively a gas centrifuge facility of a useful size is not a trivial task - it is an industrial undertaking. It would probably take Iran at least four or five years to build such a facility and begin producing significant amounts of highly enriched uranium.

For use as the fissile material in nuclear weapons, uranium must be enriched to more than 90 percent in the isotope uranium-235. Iran claims that its needs uranium enriched to between about 3 and 5 per cent for use in its civil nuclear power programme. But most of the energy needed to achieve enrichments of more than 90 per cent in uranium-235 is used to reach an enrichment of up to about 5 per cent. It is, therefore, very advantageous to use low-enriched uranium as the feed material to produce weapon-grade uranium. The low enriched uranium would simply be passed a few times through the enrichment plant.

Laser isotope separation (LIS)

Uranium can be enriched using a laser method called laser isotope separation (LIS). LIS separates uranium isotopes more efficiently than gas centrifuges because it is based on the fact that each isotope of an element has a unique set of electronic energy states. Consequently, electrons of atoms of each isotope will absorb light of a specific colour (i.e., of a specific energy level). If illuminated by a laser beam containing light of this precise colour, electrons of atoms of the selected isotope will absorb photons and become excited. An atom may give up its excited electron, and become a positively charged ion. The atoms of the other isotopes will not absorb photons, because they do not have the 'right' energy, and will not be ionised. The ionised atoms can be separated from the neutral ones by an electromagnetic field.

The Iranians have experimented with an Atomic Vapor Laser Isotope Separation (ALVIS) system that consists of two main units - a separator and a laser. When used to separate uranium isotopes, natural uranium metal is vaporised in the separator, using an intense electron beam that creates a uranium vapour stream in a vacuum chamber that rapidly moves away from the uranium metal. The vapour contains atoms of U-235 and U-238.

The laser unit uses powerful copper-vapour lasers that emit beams of green-yellow light. This light energizes (excites) 'dye' lasers that emit beams of red-orange light of precisely the right colour (i.e., frequency) to photoionise preferentially U-235 atoms. The red-orange beams are passed through the vapour of uranium atoms.

U-235 atoms absorb photons of the red-orange light whereas U-238 atoms do not. The excited U-235 atoms eject the excited electrons, becoming ionised; the U-238 atoms remain untouched. An electromagnetic field moves the positively charged U-235 atoms to a collecting plate where they condense. The enriched U-235 can then be removed. The remaining uranium vapour, containing a much greater proportion of U-238 than natural uranium, flows on through the separator chamber and is removed.

The ALVIS photoionisation process has an atomic selectivity of more than 10,000 - only one ion of U-238 is produced for every 10,000 ions of U-235. This high enrichment efficiency, combined with the fact that relatively little energy is needed to operate the separator and laser systems, makes the operating and capital costs of the ALVIS process relatively low. This makes laser-isotope separation appear more attractive than other enrichment technologies.

Iranian laser enrichment research and development and the manufacture of copper vapour lasers have been undertaken in a laboratory located at Lashkar Ab'ad. A pilot plant for laser enrichment was established at Lashkar Ab'ad in 2000 and, the Iranians claim, dismantled in 2003.

Plutonium production

The Iranian government has acknowledged to the IAEA that it has irradiated uranium dioxide targets with neutrons in the Tehran Research Reactor and subsequently chemically separated the plutonium produced in the targets. According to the Iranians, only a small amount of plutonium was separated.

If the heavy water reactor being constructed at Arak is used to produce plutonium for use in nuclear weapons, it will be necessary to chemically separate the plutonium from the irradiated reactor fuel elements. The experiments performed by the Iranians in plutonium separation are, therefore, significant.


Iran is developing a number of nuclear technologies that are duel purpose - they could be used for civil or nuclear activities or in nuclear weapon programmes. These technologies are associated, firstly, with the enrichment of uranium and, secondly, with the construction of a heavy water reactor. The enrichment activity may lead to the production of low enriched nuclear fuel suitable for use as nuclear fuel in the civil nuclear-power reactors that Iran intends to operate and/or the production of highly enriched uranium for use as the fissile material in nuclear weapons.

The IR-40 heavy water reactor being constructed by Iran will, it says, produce radioactive isotopes for medical and industrial uses. But the reactor could also be used to produce effectively plutonium that could be used to fabricate nuclear weapons. IR-40 could produce about 8 kilograms of plutonium a year, enough to produce two nuclear weapons a year.

Iran has been involved in nuclear technology for a long time - 40 years or so. It therefore has a strong cadre of nuclear physicists and engineers that could be diverted to design, develop and fabricate nuclear weapons if Iran's political leaders took the decision to do so. What Iran does not have today is significant amounts of fissile material - highly enriched uranium or plutonium - needed to produce nuclear weapons.

The activities now underway in Iran could, however, eventually provide Iran with such fissile material. Iran would then be able to deploy rapidly a nuclear weapons force if it takes the political decision to do so. Iran has ballistic missiles that could deliver nuclear warheads. Hence, the international concern about Iran's current nuclear activities.

Are these activities explicable as part of a civil nuclear programme to generate electricity and produce isotopes for peaceful purposes? The only other explanation is that they are part of a nuclear-weapon programme.

It should, however, be emphasised that there is no firm evidence that Iran intends to fabricate nuclear weapons. As reported in the International Herald Tribune on 6th November 2004, Mohamed El Baradei, Director General of the IAEA, said: "We haven't seen any concrete evidence that points to a fact that Iran has a nuclear weapons program" although he went on to say: "We have seen Iran experimenting with all aspects of the [nuclear] fuel cycle".

Three European major powers - Britain, France and Germany - are currently trying to persuade Iran to give up some of those dual nuclear activities that they suspect may be being used by Iran in a nuclear-weapon programme. In particular, they seek suspension of all Iranian activities related to uranium enrichment until a long-term agreement is negotiated on Iran's nuclear programme as a whole. Iran wants any suspension to be limited to six months and for some enrichment activities to be exempted from suspension.

In return for a suspension of its whole enrichment programme, the European countries are, in the latest negotiating move, offering Iran some civil nuclear technology and materials, including a (light-water) research reactor and a supply of nuclear fuel, as well as increased trade and assistance with reductions of Iran's regional security concerns. The Bush Administration would prefer that the nuclear activities in Iran be referred to the UN Security Council for discussion. Time will tell whether or not the negotiations succeed.

Frank Barnaby is the Nuclear Consultant to Oxford Research Group and a freelance defence analyst.

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