UNSC Resolution 1874:

12. Calls upon all Member States to inspect vessels, with the consent of the flag State, on the high seas, if they have information that provides reasonable grounds to believe that the cargo of such vessels contains items the supply, sale, transfer, or export of which is prohibited by paragraph 8 (a), 8 (b), or 8 ( c ) of resolution 1718 (2006) or by paragraph 9 or 10 of this resolution, for the purpose of ensuring strict implementation of those provisions;

With the passage of UNSC resolution 1874 last Saturday, a young techno-wonk’s thoughts immediately turn to the question of how do you have reasonable grounds to stop a ship on the high seas. (I hope to look at the legal questions in a future post, after I finish with these practical details.) We will only consider some of the issues related to nuclear proliferation here. Some rough numbers immediately jump to mind. These include things like: how many centrifuges can you ship in a single cargo container? How many centrifuges fit on a single ship? What is the “background” to detecting such a ship? (Background in the physicist’s sense: is there a lot of shipping going into and leaving North Korea that could “mask” the WMD ship?) Could you detect the loading of a ship using photoreconnaissance satellites? UAV’s? How could you track it? So here goes:

1) How many centrifuges fit in a cargo container? Libya’s centrifuges were packaged in boxes roughly 2m by 0.6 m by 0.3 m. (All these numbers are rough. We just don’t need better accuracy, as you will see.) We know from images released by the US government that two outer casings were shipped in each box. Since you cannot ship the rotors already in the centrifuge (it damages the ball bearing the rotor rests on; P-1 designs are assembled on site), there is probably another box with two rotors in it that was not shown for nonproliferation reasons. If we assume roughly the same size of box, that means that a standard shipping container (which is roughly 14.6 m by 2.5 m by 2.5 m) could carry, on average, 96 complete centrifuges.

2) How many centrifuges onboard a cargo ship? If you look at the port of Rajin, there is a bulk cargo ship at the only Port in North Korea that I have seen (see North Korea Economy Watch ) with port-based cranes whose below-decks storage area measures roughly 112 × 25 × 21 meters so it could fit 630 such cargo containers below decks. That means a grand total of 60,480 centrifuges could be carried onboard a single ship. Since, as Alex Glaser has shown in his wonderful paper Characteristics of the Gas Centrifuge for Uranium Enrichment and their Relevance for Nuclear Weapon Proliferation, Libya’s design for a “cascade interconnect” bomb factory needed only 5800 centrifuges to enrich over three bombs worth of weapons grade uranium from natural in a year. That would fit in about 61 cargo containers. Clearly, a single ship can pose a significant proliferation risk!

Tomorrow, we will consider some of these other questions.

Update (6 pm): The New York Times reports that the US will not board by force any ships sailing out of North Korea. That was clear from the wording of the resolution: “with the consent of the flag State.” I wonder how many, if any, ocean-going carrier vessels North Korea has. Does anyone know of a publicly available list of ship flagging? My guess would be nearly zero ships owned by the DPRK.