Jeffrey LewisPak Bomb Factory

David Albright and Paul Brannan of the Institute for Science and International Security (ISIS) released commercially available satellite images of a new Pakistani plutonium production reactor under construction.

(Here is a GoogleEarth placemark.)

This is really great work. Precisely the kind of open source analysis that I admire. The revelation made the front page of the Washington Post (Joby Warrick, “Pakistan Expanding Nuclear Program Plant Underway Could Generate Plutonium for 40 to 50 Bombs a Year, Analysts Say,” Washington Post, July 24, 2006, A1).

There is just one thing—I spent a few days trying to redo the calculation. I don’t think the satellite images provide enough data to do it.

I think they had some help.


Albright and Brannan claim the new plant would be capable of operating “in excess of 1,000 megawatts-thermal.”

I asked around and, apparently, the core power density (thermal megawatts per cubic meter) is roughly constant for a given type of reactor (e.g., PWR, BWR, HWR, GCR, etc.).

Given a constant core power density (say my friends) the new reactor vessel would be not quite three times as large as the current one. (50 MWth x 27, or 33, equals 1400).

A 1400 MWth reactor is capable of producing about 1.4 kg of plutonium a day, or 500 kg of Pu a year, or 60 bombs a year. So, the reactor has to be a wee bit smaller. And, yes, Virginia, there is a lot of rounding in that calculation.

Yet, to estimate that the new reactor is almost three times as large, one would need the volume of both the old and new reactor vessels. Yet the satellite image contains only the diameter of the new vessel—one has to assume that the length is proportional to the diameter.

The real question is: where did ISIS get the volume of the existing reactor vessel, shrouded in a containment dome?

I haven’t seen specifications for the Khushab reactor floating around? Have you, dear readers? If one could get the volume of the existing reactor vessel, then one can do the calculation, roughly.

Assuming they are the same reactor design.


One motive for someone inside to help ISIS is clear: The Administration is pushing the US-India nuclear deal through Congress. Not surprisingly, Joby Warrick at the Washington Post reports, the Administration decided not to share the intelligence with Congress, intelligence which might have undermined the deal.

So, what better way to stick it to the deal than point out the Administration has been hiding a gi-normous bomb factory under construction in Pakistan?


  1. John Field (History)

    A guess…

    The fuel rods hang vertically, water flow is therefore also vertical for low drag. Holding the operating temperature and pressure the same, the amount of heat that the water can take up is also the same. Therefore, height shouldn’t scale. Keep in mind as well that neutron economy changes due to water density changes at temperature.

    It seems like in practice, there would be an optimization that would space the rods slightly farther while also making the vessel taller, but not quite proportionately. A bigger reactor should have less surface area neutron loss and this could compensate for slightly larger rod spacing providing space for more water. So, I might suggest a power law scaling(less than 1) in height versus diameter.

    So, I think someone ‘skilled in the art’ of weapons grade plutonium production probably could estimate from the satellite image. Don’t know if that was done by Albright or others.

  2. Lakshmi Krishnan (History)

    Let us see. If it is a secret project without safeguards, Pakistan is more likely to build a heavy water reactor. Because there is a lot of experience with that type. Also, indigenous production of heavy water and natural uranium point to it. There is no need for complex calculation of power density, heat transfer etc to determine the reactor type or size.
    A typical 250 MW electrical reactor would have about 900 MW thermal capacity. But, it is a reactor with fuel placed horizontally. It does not hang vertically as some think. The calandria or reactor vessel is a cylinder of about 5 m dia. But, it lies on its side, not on its end. Viewed from above it would appear as a rectangle, not as a circle. How then was the diameter estimated?

  3. J (History)

    Regarding your last point on why an Administration insider would provide this information to ISIS, it is no secret that the nonproliferation bureaucracy at State is aghast at the India deal. Perfectly plausible that one of these experts, perhaps the same “experts” referenced in the Warrick article, was the source of information for the ISIS report. Albright in particular has a very strong reputation within the community.

  4. John (History)

    This being so and other nations (Iran, NK) likely to get and grow their nuclear arsenals, what sense does it make to move operations out of NORADs current locale into “the open”? We ought to be carving out more mountain fortresses, not shuttering them.

  5. s. gulika (History)

    why did this revelation come as a surprise to everyone? was there some agreement in the US intelligence community unil now that Pakistan is NOT building up its weapons capabilities? Or that its policies had changed for the better since 1998 (way back before the deal was even a glimmer in the eyes of the Bushies)?