The state-owned group said it had whittled the choice of six potential suppliers down to Britain's Rolls-Royce SMR and American GE Hitachi Nuclear Energy.

In November 2023, Sweden's government said it wanted to massively ramp up nuclear energy.

It said it wanted to increase production equivalent to two nuclear reactors by 2035, with a "massive expansion" to follow by 2045.

"The next steps will involve detailed analysis of the proposals made by the two shortlisted SMR suppliers," Desiree Comstedt, head of new nuclear power at Vattenfall, said in a statement.

They would then jointly set "a timetable for the option of building small modular reactors to enable new nuclear power generation on the Varo Peninsula," Comstedt said.

Vattenfall has previously said the area can accommodate three to five SMR reactors.

The state-owned utility said it was also continuing to investigate the conditions for building large-scale reactors on the site.

The suppliers included in that evaluation were US group Westinghouse, France's EDF and South Korean firm KHNP.

"We haven't made a choice of reactor technology yet," Comstedt said.

Vattenfall reiterated its ambition to have a first reactor, regardless of type, in operation at Ringhals "in the first half of the 2030s at the earliest".

SMRs are advanced nuclear reactors that have a power capacity of up to 300 megawatts of electricity per unit, or about a third of the generating capacity of a traditional nuclear power reactor.

They are relatively simple to build, which makes them more affordable than large power reactors.

The Scandinavian country voted in a 1980 non-binding referendum to phase out nuclear power.

Since then, Sweden has shut down six of its 12 reactors and the remaining ones, at three nuclear power plants, generate about 30 percent of the electricity used in the country today.

In 2016, a broad political majority agreed to extend nuclear power for the forseeable future, paving the way for new reactors to be built to replace the ageing ones at the end of their lifespans.