The government plans four large-scale reactors - with installed capacity of about 5000 megawatts - or the equivalent in small modular reactors (SMRs).
Half of that should be on-stream by 2035, according to the government.
"It's a question guaranteeing Swedish jobs, for dealing with climate change and it's a question of Sweden's security," Financial Markets Minster Niklas Wykman said during a debate in parliament on Wednesday.
Electricity demand is expected to double to about 300 terrawatt hours over the next two decades and the government says without nuclear power, key new industries like green steel, bio-fuels and large-scale hydrogen production will go elsewhere.
The government says it supports all fossil-free energy production,but that only nuclear can supply reliable and predictable power.
A white paper published in August last year, which proposed a similar model, said the state could need to lend nuclear developers between 300-600 billion crowns ($A48-$A96 billion).
Price guarantees would stay in place for 40 years.
Critics say nuclear power will be too expensive and too slow to build and would squeeze out cheaper wind and solar which are the only way to meet increased demand in the short term.
"It is an item of religious faith for this government to build nuclear power whatever the price," Birger Lahti of the opposition Left Party said.
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