[🇵🇰] The Uranium Route to the Bomb:

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The Uranium Route to the Bomb: PAEC's role in Uranium Enrichment

Pakistan from the outset of the Multan conference was exploring both the Plutonium and Uranium routes to the bomb. During 1974-76, uranium enrichment was probably seen as a backup or at most a co-equal programme for fissile material production. Having two different technologies for production would make Pakistan more resistant to efforts to restrain its programme, and producing both U-235 and plutonium would give Pakistan greater flexibility in weapon design. Dr. Bashiruddin Mahmud was only one of dozens of scientists and engineers (besides) AQ Khan who were working in Europe, Canada and the US in late sixties and early seventies that later became “Consortium Companies” to supply enriched uranium to European nuclear power plants. PAEC brought back dozens of scientists from Belgium to start this programme under Dr Bashiruddin long before

AQ Khan came on board.

Moreover, the PAEC was already considering the centrifuge problem, and there was one experiment in Lahore in the early 1970s involving centrifuges. Two pilot centrifuge plants were set up in Golra and Sihala before the actual uranium enrichment facility was established at Kahuta. Munir Ahmad Khan completed the site selection for the Kahuta enrichment plant, initial procurement of vital equipment, construction of its civil works, and recruitment of staff for it by 1976. The Kahuta Enrichment Project was called Project-706 of the PAEC, and as with the plutonium programme, it was under the overall control and supervision of Chairman Munir Khan. A.Q. Khan came to Pakistan and produced gas centrifuge designs and drawings from URENCO. He initially worked under Project Director Sultan Bashiruddin Mahmud. Much of the buying for Kahuta of necessary materials and equipment before and after A.Q. Khan's arrival was done by a brilliant PAEC physicist-turned diplomat, S.A. Butt, who was also looking after the plutonium programmes' requirements. The best PAEC scientists and engineers staffed Kahuta. It must be remembered that the Plutonium contract with France had not been cancelled by the French government when the Enrichment Plant was being set up at Kahuta.

When Canada in 1976 suspended the supply of heavy water fuel and spare parts for KANUPP, the PAEC under Munir Khan took up the challenge and using indigenous resources produced the feed for KANUPP. As a result the Muslim World's first nuclear reactor was not closed even for a single day for want of spare parts, fuel, and heavy water.

The technology Qadeer brought would have eventually been acquired. The work had been started by Bashir-ud-din on Nuclear Fuel cycle to make fuel for KANUPP and future nuclear plants two years prior to Qadeer's arrival in Pakistan. Dr. A.Q. Khan did not bring a magic wand from URENCO but still it was a vital link to the bomb. Under Munir Ahmed Khan, PAEC started an ambitious programme to master the technology of complete nuclear fuel cycle in which “ Heavy Water” was one of the most important components. Heavy Water which was so (prohibitively) expensive which Canada was charging Pakistan $27/lb (in early/mid-seventies), Pakistan's only nuclear power plant would die and our whole nuclear programme would come crashing in late 1970. Qadeer's contribution cannot be denied but should not be overblown. Centrifuge essentially a highly specialized mechanical component was a link in the long chain of enrichment technology. As Qadeer and his team stumbled on many occasions, he received vital technical support from PINSTECH and PAEC infrastructure and scientists. Dr N Ikram out of many (Punjab University, Institute Of Solid State Physics) was a rare specialist in this field and international authority who came to his rescue.

Qadeer's blueprints were based on first generation enrichment technology originally developed by the URENCO in late sixties and early seventies whose SWU (unit of the measurement to separate U-238 and U-235 in natural uranium in order to create final product that is richer in U-235 (atoms) was so low that thousands of centrifuge machines would have to be deployed for thousands of hours at performance levels much inferior to then installed centrifuges at URENCO. PAEC (under Mr. Munir Ahmad Khan) challenged its economic viability and presented a programme that will deploy the most efficient technology by setting up an infrastructure for advanced machine design for the next generation centrifuges and in the two decades that followed spent more than $3 billion on centrifuge technology and its support infrastructure. PAEC used “proven technology” with heavy emphasis on R&D (not copy or stealing as US and western media says) with much higher SWU while reducing costs and improving efficiency through the use of state-of-the-art materials, control systems and manufacturing processes.

By late 90s, KRL had conducted centrifuge development work costing hundreds of millions of dollars. PAEC enabled KRL to take advantage of commercial advances in construction materials (thanks to PAEC/PINSTECH's Scientists) and advanced manufacturing methods to develop a centrifuge machines that achieved several times SWU performance previously demonstrated by early KRL machines, but at substantially reduced cost. Today PAEC has a workhorse technology that capably serves Pakistan defence needs and since New Labs setup, much of the fuel needs of the future nuclear plants in Pakistan.

People might ask the significance of higher SWU? Natural uranium, in the form of uranium hexafluoride (natural UF6), is fed into an enrichment process. If (for example), you begin with 50 kilograms of natural uranium, it takes about 30 SWU to produce 5 kilograms of uranium enriched in U-235 to 4. -5%. It takes on the order of (roughly) 100,000 SWU of enriched uranium to fuel a typical 137 megawatt (MW) commercial nuclear reactor for a year. A 137 MW (KANUPP) plant can supply the electricity needs for a city of about 500,000 in a country like Pakistan.

Moreover, the technology brought by A.Q. Khan was based on the URENCO designs of gas centrifuges for enriching uranium to weapon grade, also known as Highly Enriched Uranium (HEU). But again, A.Q. Khan's uranium enrichment was not independent of PAEC, even after having acquired total control and autonomy for KRL. In order to enrich uranium to weapon grade, he needed the crucial Hexafluoride gas, known as UF-6. Concurrent to the plutonium programme and the setting up of Project-706, the PAEC was also setting up a plant to produce Uranium hexafluoride, which is a crucial ingredient for enriching uranium. Here is how UF6 produced and supplied by PAEC to KRL is critical to Enriching Uranium through gas centrifuges and it underlines the importance of this very important 'step' in a series of interconnected steps that lead to a bomb. KRL depends on PAEC for Enriching Uranium as is illustrated here. KRL's role in centrifuges and vacuum technology and material is not being denied here, but PAEC's role is highlighted which is unknown and unacknowledged and unsung and all praise only goes to A.Q. Khan.

 

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The PAEC at its HEX PLANT produces Uranium Hexafluoride (UF6). Here the natural uranium ore concentrate is sent to a conversion plant where it is chemically processed into Uranium Hexafluoride (UF6). At ambient temperature, UF6 is a solid with a low residual vapour pressure. It is then handed over to KRL.

At KRL enrichment plant, a centrifuge comprises an evacuated (vacuum) casing containing a cylindrical rotor, which rotates at very high speeds, in an almost friction free environment. The Uranium is fed into the rotor as gaseous Uranium Hexafluoride (UF6) where it takes up the rotational motion. The centrifugal forces push the heavier U-238 closer to the wall of the rotor than the lighter U-235. The gas closer to the wall becomes depleted in U-235 whereas the gas nearer the rotor axis is enriched in U-235.

The gas flow is produced by a temperature gradient over the length of the centrifuge. UF6 depleted in U-235 flows upwards adjacent to the rotor wall, whilst UF6 enriched in U-235 flows downwards close to the axis. The two gas streams are removed through small pipes.

The enrichment effect of a single centrifuge is small, so centrifuge pumps are linked in-groups known as cascades. Passing through the successive centrifuges of cascades, the U-235 is gradually enriched to the required percentage - usually between 3 and 5% and the depleted uranium is reduced to 0.2 to 0.3% U-235. Enrichment achieved to 5% is non-weapon grade low enriched uranium used in nuclear power plants whereas HEU weapon grade is over 95%.

So Enriching Uranium does not start or end completely at KRL after which the enriched uranium is manufactured into a bomb, which involves very critical steps of developing the bomb design, implosion techniques, triggering mechanism etc. The work on the bomb itself had begun in earnest in the early 1970s by PAEC in a meeting called by Chairman Munir Khan, and attended by Dr. Ishfaq and other senior scientists at about the same time that the Indians exploded their Smiling Buddha. The Hex Plant was built by PAEC under Munir Khan's Chairmanship and it confirms the fact that this plant was built for providing UF6 to KRL, which was Project 706 of PAEC, developed under Bashiruddin Mahmud, before A.Q. Khan came.

There is no doubt that Munir Ahmad Khan was a true visionary, architect of Pakistan's uranium enrichment and plutonium programmes and way ahead of his time at PAEC or PINSTECH. He believed and worked tirelessly in building infrastructure that would fabricate nuclear fuel for Pakistan's nuclear plants and would be a springboard for Qadeer's fame and notoriety. Without getting hands around fuel cycle's first 3 crucial steps - 1) mining (uranium ore mining from mines), 2) milling (uranium ore into yellow cake), 3) conversion (yellow cake into hexafluoride) enrichment would be impossible for which PAEC laid solid ground work very early on. Enrichment, a step in increasing the concentration of U-235 isotopes from its natural level (0.5-.7%) to 5% level (fuel used in nuclear plants) was started by Bashiruddin Mahmud, under Munir Khan's directions. Dr. Bashiruddin did a complete feasibility of the project as early as 1974. Bashirudin was real enrichment (nuclear) expert not a metallurgist. These are two very different disciplines that should not be confused with each other.

Fuel fabrication (the 4th step) - the process of enriched uranium into uranium dioxide, sealing it into metal fuel rods and bundling into fuel assembly, and the last step - fuel fabrication (fuel into nuclear plants where U-235 starts fission producing heat and running the turbine etc) for power plants was again the work of PAEC.

Technically speaking, KRL never built an atomic device for Pakistan but it did build lots of centrifuges, which is purely a mechanical device. PAEC provided technical assistance and guidance in all-important areas of enrichment (and much more) to KRL, as centrifuge was the “vehicle” to the enrichment process.

Much of the KRL time (as an organization) was spent designing, developing centrifuges, identifying and resolving the most difficult cascading and other problems to the very end of the programme. From the beginning, more than 75% of KRL scientists and engineers were from PAEC, although many more with rare expertise were recruited from a diverse pool of Pakistani scientists and engineers working in the US and Europe. PAEC played an important role from the very beginning, and thus their know-how became increasingly important in the overall programme. Without PAEC involvement, KRL abilities could not have grown beyond an advanced machine design shop.

PAEC knew how to make nuclear fuel for civil applications before KRL was established. Without PAEC /PINSTECH active guidance and participation, KRL centrifuges (in all likelihood) could only have produced low-enriched uranium, not the highly enriched material needed for an atomic weapons. Simply describing, production of low enriched to highly enriched Uranium is not a “linear” process, which means that if you can produce low enrich uranium, you cannot or may not (readily) produce HEU.

After 30 years of research into the uranium enrichment, Pakistan is now one of the 12 major players in the world that has mastered gas centrifuge technology. This technology with its dozens if not hundreds of spin-off hold the key to the security of Pakistan, future nuclear energy and fuel requirements. People would be surprised to know that laser enrichment programme in the US and Europe and Israel recently hit a dead end.

 

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The Indian Atomic Energy Commission and BARC (BARK) have fresh proposals to revive the development of the gas centrifuge technology, which never got off the ground in the first place, whereas Pakistan had a continuous and on-going development programme for three decades. We now have latest generation of machines in operation (Pakistan's sixth generation), which is as good as if not better than any European machine. The strategy and risks behind Pakistan development programme were too many and what PAEC did no organization in the world would have done it in view of the resources allocated and severe restrictions to import dual use technology.

Hence, it is clear that the Pakistani enrichment development was begun in 1974 by Chairman PAEC, Munir Ahmad Khan, under several covert programmes and one based (URENCO early model) on the concept of a lightweight rotor operating on pin bearings and magnetic top bearings got the most publicity in the west. Other parallel programmes Pakistan started were based on better design parametres to achieve super-critical operating speed that would provide PAEC with wide base of advanced engineering (machine design) experience on which they helped KRL develop future generation of centrifuges.

PAEC policy was to run their programmes as economically as possible rather than just focusing on the technical benefits. This approach caused a major friction with KRL but forced KRL to shift its strategy from smuggling machines (not a reliable option) to R&D. KRL envisioned that future generations of machines would be developed from reverse engineering or they would make thousands of first generation machine, clearly a Russian approach wasting precious resources with low chances of success. KRL eventually was forced to undertake a long-term programme to develop significantly faster centrifuges through R&D under PAEC/PINSTECH guidance.

While PAEC programmes were based much more on a series of “smaller projects” aimed at improving specific aspects of the current centrifuge either by manufacturing improvements to reduce the cost of manufacture or by taking advantage of improvements in materials. In either case, all PAEC projects were evaluated from an economic point of view to ensure that lifetime cost improvements actually paid back the money committed to undertake the research and from a technical point of view to ensure that improvements were introduced as early as possible within the manufacturing phase as part of future generation. PAEC was always in favour of step by step approach in developing each centrifuge generation not just importing clandestinely some models and then reverse engineered them so they set out the development programme in three stages 1) R&D 2) Pilot and 3) Production. First step included design studies, testing of new materials, manufacture and very high stress testing of a small number of components and then building typically 20 or 30 centrifuges. The pilot phase was employed to prove that the centrifuges would operate successfully long term under all design parameters.