In 2005 Iranian officials told the IAEA of Pakistan‘s scientist A.Q. Khan‘s 1987 offer of centrifuge enrichment technology. If Iran received the same nuclear weapon design that A.Q. Khan gave Libya then we are looking at the P1and P2 centrifuges. The P1 centrifuges are based on the original 1970‘s URENCO design in the Netherlands that Khan acquired knowledge of while employed at the plant. Pakistan started with this technology to produce HEU for nuclear weapons.
advanced designs could double Iran‘s enrichment capabilities, shortening the time taken for the production of HEU for a bomb. An important advantage of the gas centrifuge over the gaseous technique of enrichment is that it is much less energy intensive, and has proven to be better performance and more reliable and have a larger unit enrichment capacity.
Fissile Material Needed to Build an Atomic Bomb
a.The amount of HEU needed to make a nuclear weapon varies with the degree of enrichment and sophistication of the weapon design.
b. In general, the higher the enrichment level, the less HEU is needed to make a bomb.
c. For a HEU-based nuclear weapon, there are two basic design options:
- Gun-type weapons are far simpler in design, whereas the implosion weapon is more difficult technically but requires less HEU
- Plutonium based nuclear weapons only work as implosion weapons, with more sophisticated weapons using less plutonium.
- Gun-type weapon and Implosion weapon.
The Fuel Enrichment Plant FEP
Iran plans eventually to install about 50,000 machines and to install the centrifuges in modules of 3,000 machines that would be designed to produce low enriched uranium for power reactors. In a case where just 1,500 of these centrifuges were installed and optimized to produce HEU, these centrifuges could produce enough highly enriched uranium for about one nuclear weapon per year.
When completed, the FEP could be used to produce roughly 500 kilograms of weapon-grade uranium annually. At 15-20 kilograms per weapon, that would be enough for 25-30 nuclear weapons per year.
Each of Iran‘s centrifuges has an output between 2-3 SWU/year (Seperative Work Unit per Year). Iran
Is planning a full scale FEP at Natanz which will eventually house 50,000 centrifuges, giving the plant a capacity of 150,000 SWU/year—enough for annual reloads of LEU for the Bushehr reactor or, if configured
differently, 25-30 nuclear weapons worth of HEU per year.
One centrifuge could produce some 30 grams of HEU per year which is equivalent to 5 SWU. As a general
rule of thumb, a cascade of 850 to 1000 centrifuge, each around 1.5 meters long operating at 400 m/sec would be able to produce about 20 to 25 kg of HEU per year, enough for one HEU bomb.
An implosion weapon using U235 would require about 20 kg of 90% U235. Roughly 176 kg of natural uranium would be required per kg of HEU product, and about 230 SWU per kg of HEU, thus requiring a total of about 4,600 SWU per weapon. To enrich natural uranium for one gun-type uranium bomb requires roughly 14,000 SWUs. Thus, producing one HEU weapon in a year would require between 1,100 to perhaps 3,500 centrifuges.