What the hell do they need a nuclear power plant for?? How much electrical infrastructure is there in Iran, anyway???
They're cooking weapons grade plutonium, mark my frakkin' words.
As for why do they need it, Iran's budget relies heavily upon their petroleum sales to the rest of the world, the more of it they don't have to burn locally, the more money they save. Add to this their surprisingly low refining capacity (they actually import the majority of their distillate fuels, ie. gasoline) and the cost savings become even higher.
To the plutonium breeding, to the best of my knowledge breeder reactors run off un-enriched (basic Ur-238/235 ratio) Uranium fuel. With how much Iran has already spent in time and money on Uranium enrichment facilities they have obviously chosen to go the HEU route for nuclear devices, rather than Plutonium, which would require both the time and money intensive steps of first breeding it, and then running it through a similar separation and enrichment process like they do with the Uranium (HEU bombs eliminate one of those steps and are thus cheaper and quicker to make).
As it sits, the enrichment centrifuges pose a significantly higher danger, regarding the creation of a nuke, than a reactor that may possibly be a breeder design, and they already have the materials to create dirty bombs if they wished (uranium oxides). In the interest of full disclosure, HEU does have uses in nuclear power, a reactor running off 4% enriched fuel rods for example can run for about 6 months non-stop, a reactor running off 90+% fuel rods, considered weapons grade, can run for about 20 to 30 years before refueling. Guess which kind of rods the Navy uses?