The constraints on the size of Israel's stockpile include several potential variables, several of which are generic to any nuclear weapons program. The Dimona reactor may have operated an average of between 200 and 300 days annually, and produced approximately 0.9 to 1.0 grams of plutonium for each thermal megawatt day. Israel may have use between 4 and 5 kilograms of plutonium per weapon [5 kilograms is a conservative estimate, and Vanunu reported that Israeli weapons used 4 kg].

The key variable that is specific to Israel is the power level of the reactor, which is reported to be at least 75 MWt and possibly as high as 200 MWt. New high-resolution satellite imagery provides important insight this matter. The imagery of the Dimona nuclear reactor was acquired by the Public Eye Project of the Federation of American Scientists from Space Imaging Corporation's IKONOS satellite. The cooling towers associated with the Dimona reactor are clearly visible and identifiable in satellite imagery. Comparison of recently acquired commercial IKONOS imagery with declassified American CORONA reconnaissance satellite imagery indicates that no new cooling towers were constructed in the years between 1971 and 2000. This strongly suggests that the reactor's power level has not been increased significantly during this period. This would suggest an annual production rate of plutonium of about 20 kilograms.

Based on plausible upper and lower bounds of the operating practices at the reactor, Israel could have thus produced enough plutonium for at least 100 nuclear weapons, but probably not significantly more than 200 weapons.

Some type of non-nuclear test, perhaps a zero yield or implosion test, occurred on 2 November 1966 [possibly at Al-Naqab in the Negev]. There is no evidence that Israel has ever carried out a nuclear test, although many observers speculated that a suspected nuclear explosion in the southern Indian Ocean in 1979 was a joint South African-Israeli test.