Pakistan's uranium enrichment capacity is generally believed to be centered at the A.Q. Khan Research Laboratory (KRL) located a bit outside the dusty city of Kahuta in north-eastern Pakistan. The centre was founded and directed by the nuclear black-marketeer Abdul Qadeer Khan in the 1970s. The industrial park was created in direct support of the Pakistani weapons program. And, according to A.Q. Khan himself, Pakistan got the capability to detonate a nuclear device (and thus had enriched enough uranium) by the end of 1984. It is widely assumed that Pakistan upheld a moratorium on the production of fissile materials for weapons purposes during the 1990s (although this was never verified). It is likewise assumed that production started again after India's second round of nuclear testing in 1998. It is not known if the plant escaped damage after the 8 October 2005 earthquake that shook the region. Pakistani officials claim that it escaped unharmed.
But what is the capability of this plant today? Well, figures are both unreliable and, in addition, some sixteen years out of date. It is sometimes assumed in the literature that the facility has some 3,000 centrifuges operating at any given moment, and that the capacity of the plant is somewhere between 9,000 and 15,000 separative work units. These figures rely on open source information compiled and assessed by the Stockholm International Peace Research Institute. (Albright, et al., 1997). The authors of the study readily admit that "the number of operating machines at any one time is highly uncertain. Part of the confusion is that Pakistan has installed considerably more machines than it has successfully operated. In 1986, it was reported that Kahuta had 14,000 centrifuges." (See p. 275). Yet, the claim that the plant is capable of a meager 15,000 SWU's resurface time and time again. Over the last couple of weeks, I have been compiling a Google Earth placemark of the A.Q. Khan Research Laboratory, cross-checking with public imagery analysis to get a complete picture of the facility. Almost immediately, I suspected that the 15,000 SWU figure might be grossly misleading.
For instance, in 2005, the United States presented an image of the Kahuta Labs, and two structures were highlighted as centrifuge cascade halls. I am not sure why these two were selected by the United States' skilled analysts, and not other similarly sized buildings in the complex. Also, the US briefing (which in all fairness was about Iran, not Pakistan) did not touch upon the structures located in what's known as the "southern production area". This is a better image of what's known as the "northern production area", captured from Google Earth.
One useful tool in Google Earth is the measuring device, which allows the user to accurately measure distances on the ground. Using that tool, it is possible to ascertain the total floor space of the two buildings, which the U.S. has designated as cascade halls.
Building | Length | Width | Square meters |
Western (lower) building | 125 | 60 | 7,500 |
Eastern (upper) building | 115 | 85 | 9,775 |
Total | 17,275 |
Using a popular rule of thumb, that one centrifuge requires one square meter of floor space, the facility's dimensions easily swallows over 17,000 centrifuges. Indeed, these two buildings alone could house more capacity if centrifuges are stacked vertically. While it is highly unlikely that all floor space have been used up, the size of the buildings strongly suggests that more than 3,000 centrifuges are installed in this area. If one assumes that one third of each building is offices, staff facilities, control rooms, workshops, empty space etc, and, moreover, that only half the centrifuge hall is utilized, it seems more likely that 10,000 to 14,000 centrifuges are installed. This figure is mentioned in Albright et al, but does not seem to have gotten much traction in other literature.
So what is the capacity of the plant today? Well, it is assumed that the facility was renovated in the 1990s and that the P-2 centrifuges installed at that time has been replaced by more effective machinery.
Desig. | Derivation | Rotor | Velocity (m/s) | Length | SWU |
P-1 | SNOR/CNOR | Aluminum | 350 | 1-2 | 1-3 |
P-2 | G2 | Maraging Steel | 500 | 1 | 5 |
P-3 | URENCO 4M | Maraging Steel | 485 | 2 | 11.6 |
P-4 | SLM/Unknown | Maraging Steel | 508 | 3.2 | 21 |
Adapted from <http://www.armscontrolwonk.com/1399/p3-and-p4-centrifuge-data>
Data on the capacity of Pakistan's centrifuges have been published by Nuclear Fuels (and has been reproduced by the Arms Control Wonk for the benefit of the poorer community). It is also assumed (at least here, here and here) that Pakistan's conversion facility at Dera Ghazi Khan is capable of producing 200 tons of uranium hexafluoride gas per year. If one assumes that Pakistan has installed 10,000 centrifuges and is enriching its product to the U.S. weapons grade level, and that they are setting their tails assay fairly high (to 0.4 per cent), the required feed perfectly matches (by a fraction) the annual production capacity of Dera Ghazi Khan. In other words, the rest of Pakistan's nuclear infrastructure fits around a centrifuge program centered on 10,000 centrifuges.
Centrifuges | Type | SWU | UF6 Feed (tons) | Product (kg) |
10,000 | P-2 | 50,000 | 200 | 283 |
Product | 93% | |||
Tails | 0.4% |
However, if one assumes that Pakistan upgraded their facility in the mid 1990s, the picture is more worrying. Kahuta then has an enrichment capacity almost ten times higher than what is usually assumed. With so many centrifuges in operation, the Kahuta director will have to lower the tails assay to a more normal 0.3 per cent, or stretch the conversion facility beyond its capacity.
Centrifuges | Type | SWU | UF6 Feed (tons) | Product (kg) |
10,000 | P-3 | 116,000 | 194 | 580 |
Product | 93% | |||
Tails | 0.3% |
Finally, if one assumes that Pakistan has upgraded to their latest model (which David Albright may refer to in this article, where he talks of "10,000 uranium enrichment centrifuges, which rotate at supersonic speeds on high-tech magnetic bearings"), the production capacity of Kahuta becomes huge. It is not very likely that Pakistan has this much capacity installed at the facility. Rather, the management is likely to have a combination of centrifuges installed, from first to later generations, much like the setup at Urenco (Capenhurst) in the United Kingdom.
Centrifuges | Type | SWU | UF6 Feed (tons) | Product (kg) |
10,000 | P-4 | 210,000 | 196 | 799 |
Product | 93% | |||
Tails | 0.15% |
A very high SWU capacity does not fit the assumed production capability of the uranium conversion facility. The tails must be set ridiculously low, which does not make sense from a production standpoint. This could mean three things. Pakistan has more uranium conversion capability than is previously thought, the facility is not running all the time, or Pakistan has adjusted their SWU capacity to fit their conversion capabilities. To enrich the uranium contained in 200 tons of uranium hexafluoride gas (to 93 per cent uranium-235 with tails set to 0.3 per cent), Pakistan would need to invest something like 120 000 SWU. This figure fits neatly with the P-3 setup detailed above.
There is definitely electrical power available to run the plant. At least six high voltage transmission lines feed Kahuta Research Laboratories (this is assuming that a Pakistani pylon carries six lines). If one assumes that one Pakistani centrifuge requires 130 kWh per separative work unit, a 15,000 SWU plant would require some 1.95 GWhe per year. According to an electrical engineer I spoke to, there seem to be considerable overcapacity in power transmission, if the dedicated power line is supplying a 3,000 centrifuge cascade and associated buildings. However, a plant capable of 120k SWU will require something like 15,5 GWhe of electricity for the centrifuges to spin throughout the year. The electricity feed, and the size of the step-down transformer station, fits that kind of energy consumption level quite neatly.
These transmission lines will be highlighted in my forthcoming placemark. If you don't want to wait for my placemark, you can find the step-down transformer station and its auxiliary buildings at 33°37'4.54"N 73°22'52.40"E. Then trace the pylons (and sometimes the power lines) going southwest.
Works cited
Albright, David, Berkhout, Frans and Walker, William. 1997.
Plutonium and highly enriched uranium 1996: World inventories, capabilities and policies. s.l. : SIPRI/Oxford University Press, 1997.















