Iran has unveiled two developments in its nuclear programme. Tehran says it has used domestically-made nuclear fuel in a reactor for the first time and now also has more efficient enrichment centrifuges.
State television showed President Mahmoud Ahmadinejad inspecting the rods as they were loaded into a reactor on Wednesday.
The government unveiled a "new generation" of faster, more efficient uranium enrichment centrifuges at the Natanz facility in the centre of the country.
Atomic Energy Organisation head Fereydoon Abbasi Davani said they were three times more efficient than their existing capacity.
President Ahmadinejad said last week that Iran would never halt its programme to enrich uranium.
A BBC correspondent says Iran is determined to show that it can master nuclear technology on its own, and that international sanctions against its nuclear programme will make no difference.
The moves are likely to increase fears in the United States and Israel that Iran is working on a nuclear weapons programme, which Iran denies.
In January the International Atomic Energy Agency confirmed that Iran had started the production of uranium enriched up to 20% at its Qom plant.
The United States downplayed the announcement.
The State Department said on Wednesday the statements don't amount to much.