A "breakthrough understanding" to fling open India's nuclear power sector to U.S. firms reached during President Barack Obama's visit to New Delhi last month could be finalized this year, Indian officials have said.

The Jan. 25 announcement by Obama and Indian Prime Minister Narendra Modi followed six weeks of intensive talks, but few details were released beyond a framework based on India's acceptance of the principle that plant operators should bear primary liability in the event of a nuclear disaster.

Significant work remains on the fine print of a deal aimed at unlocking projects worth tens of billions of dollars. India wants to nearly treble its installed nuclear capacity, a move that would make it the world's second biggest market after China.