Let us return to the armscontrolwonk post on the reactor core size at Al Kibar and deconstruct it given that shocker from ASPI.
According to the information provided by Team Bush the number of fuel channels in the Al Kibar reactor fuel assembly is 52 arranged in a 4-6-8-8-8-8-6-4 arrangement. At North Korea’s Yongbyon we have 5-7-9-11-11-11-11-11-9-7-5 which gives us 97.
The upshot here is that these numbers can be arranged graphically which enables us to develop a comparative calculation of their energy outputs on the basis that the volume of the reactor core, taken to be a sphere, models its energy capacity. The equation for the volume of a sphere is
V(s)= 4/3Pr^3
Where P is pie and r^3 is the radius cubed. You can see from the above configurations that it is apt to conclude that the capacity of Al Kibar is about 15% that of Yongbyon on grounds that the original calculation was done using 56/97 ratio not 52/97 ratio. The 56/97 ratio gives 20% of the Yongbyon energy output.
However, it might well be the case that the appropriate configuration here is a not a sphere but a cylinder
V(c)= 4Pr^2h
Where h is height.
Until there is compelling reason to think otherwise I think it would be apt to stick with the sphere on grounds that a figure for h is all rather uncertain. For Forden you still scale by r^3 as can be seen in the comments section of the above post which means that the sphere calculation is as good as it gets.
Yongbyon has a 5MWe capacity. To calculate plutonium production it is better to convert this into megawatts thermal and the rule of thumb is that MWt is 3 times the size of MWe. So, for Yongbyon we have 15MWt.
A thermal nuclear reactor operating at 1MWt produces 1.23 grams of U-235 per day or 449.26 grams per year. Such a reactor would produce Pu-239 according to the following formula
449.26×0.806x(239/235)
Or 368.27 grams per year.
For 15MWt (although 25-30MWt is the figure cited for Yongbyon) we get 5524.05 grams of Pu-239 for Yongbyon. Going on the 1/5 calculation of the volume of the Al Kibar reactor core we get a power output for Al Kibar of 3MWt which gives us 1104.81 grams of Pu-239 a year. Going on 15% gives us 828.6 grams of Pu-239 a year. Notice even if we have 15MWt we don’t have an SQ for one Fat Man Pu based bomb (6kg Pu-239) let alone 2 a year as claimed. The US estimate makes sense on the basis of Pu fissile core bombs of more technical design than Fat Man but that implies boosting or composite cores…nobody is saying that Syria can do this.
You can see however you do the calculation you still get a reactor core volume for Al Kibar less than Yongbyon.
As pointed out below that is pretty inefficient for Pu production for weapons purposes.
Update. Most Magnox reactors built in the UK used spherical pressure vessels. The Calder Hall reactors, which the Yongbyon 5MWe is based upon, used a closed circuit cooling system. The pressurised closed circuit system enables more efficient Pu production. The higher the pressure the more costly and the less safe is the system. At Calder Hall the CO2 gas was maintained at 8 atmospheres or about 120psi (like a Tour de France road bike). How high was the pressure designed for Al Kibar?
