Consider the following statements regarding uranium enrichment: 

1. Centrifuges enrich uranium by spinning uranium gas at high speeds, increasing the proportion of the fissile isotope U-235.

2. Highly Enriched Uranium (HEU) is used in nuclear reactors, while Low Enriched Uranium (LEU) is primarily used for nuclear weapons.

3. Advanced centrifuges can enrich uranium more efficiently, requiring fewer machines compared to older designs.

How many of the statements given above is/are correct?