Question

In Iran, Uranium is being enriched using centrifuges. In the 1940’s and 1950’s USA Uranium was enriched using mass spectrometry. Why did the Iranians choose not to use mass spectrometry?

Answer 1

This is due to the low cost, in energy, of enrichment per unit  of uranium. It's cheaper to use centrifugal isotope separation than the use of mass spectrometry. However, mass spectrometry produces highly enriched uranium compared to centrifugal. Additionally, mass spectrometry requires a less mass of natural uranium (NU) to produce the desired enriched uranium.