The decision will trigger a major battle with Left-wing Labour MPs and environmental campaigners.
The Prime Minister indicated in his New Year message to the country that the Government was prepared to take the "difficult decision" of upgrading nuclear power plants.
He believes nuclear power is an effective way of helping Britain meet its energy needs - amid concerns over oil and gas supplies from Russia and the Middle East - while tackling climate change.
The announcement will follow a five-month public consultation which has already been branded a farce by opponents.
They are preparing a legal challenge to any pro-nuclear findings.
Senior sources in the Department for Business and Enterprise insisted: "Dozens of individuals and organisations have contributed to the consultation and we have taken account of everything they said.
"Given the circumstances we will be facing, it is inconceivable that we should prevent nuclear from being part of our energy mix."
In a bid to head off criticism, Business Secretary John Hutton will avoid announcing how many reactors the Government believes should be built or where they will go. He will say it is up to the industry to come forward with proposals.
But any new plants would be built in a band across the South - most likely on the sites of old power stations due to be decommissioned in the next few years. The favourites are Hinkley Point in Somerset, Bradwell in Essex, Sizewell in Suffolk and Dungeness in Kent.
The Government is certain to have a rocky ride. Last February a High Court judge ruled that an earlier consultation had been "seriously flawed" and no decision could be based on it. Green groups have already written to the Treasury Solicitor with claims that the new process had been blighted by similar flaws.
Liberal Democrat environment spokesman Steve Webb said: "Nobody believes this second consultation was any more genuine. It is obvious the Government has already made its decision - ministers could barely be bothered to moderate their pro-nuclear language."
Ministers are confident that their case is watertight, but they are resigned to a fresh legal battle.
In another blow for Mr Brown, Britain's top nuclear energy economist has undermined his case.
Professor Gordon MacKerron of Sussex University, who recently headed a government advisory committee on radioactive waste, admitted he had "serious misgivings about the legitimacy of the consultation process" and called Ministers' position on the economics of nuclear power Â“overly optimisticÂ”.
Many Labour MPs are fiercely opposed to renewing atomic stations, believing they are an environmental hazard, a burden on the taxpayer and a poor substitute for renewable energy such as wind and wave power. The Government may need to rely on the Tories in a Commons vote.