South Africa will consider adding nuclear power capacity in an affordable way as part of its long-term plans, Mineral Resources and Energy Minister Gwede Mantashe said on Tuesday.

President Cyril Ramaphosa put on hold plans by his predecessor Jacob Zuma for a massive nuclear project last year because of fears it could collapse the economy, but senior officials have since indicated that plans for new nuclear haven't been shelved entirely.

Mantashe, a former trade unionist, took over a merged energy and mineral resources ministry in May and told parliament last month that South Africa should start planning for new nuclear to come online after 2045.

South Africa operates Africa's only one nuclear power plant near Cape Town and is working to extend its life by 20 years to 2044.

Investors have tended to worry when South African officials express support for nuclear because of the country's severe fiscal constraints, which endanger its last investment-grade credit rating. Energy experts say adding new nuclear is more expensive than other power options.

"It comes back to a resolution we took as a government: not going big bang into nuclear, but going at a pace and price that the country can afford," Mantashe told reporters. "The fact that we suspected corruption (in the Russia deal) doesn't mean that nuclear is irrelevant for the country in 2019."

Mantashe would not give a timeframe for any nuclear new build, saying the government's energy plan needed to be approved first.

That plan, called the Integrated Resource Plan (IRP), has been held up by negotiations with business and labour, but the minister said he hoped the IRP would be taken to cabinet in the next two to three weeks.

Mantashe added that the IRP contained provisions for "modular nuclear technology", implying government would contemplate adding nuclear reactors on a smaller scale than in the past.

Johannesburg-based independent energy analyst Chris Yelland said South Africa was still a long way from procuring new nuclear reactors.

"Just because it's in the IRP doesn't mean it's going to happen," Yelland said.

After the IRP is published, which could take months, the energy regulator will be consulted before the National Treasury does an assessment of what's affordable, he added.

POWER CONSTRAINTS
South Africa wants to supplement its power capacity because of faults at state utility Eskom's fleet of creaking coal-fired power plants, some of which will be decommissioned over the next two decades.

Eskom, which is reliant on state bailouts to survive, implemented some of the worst power cuts in several years in the first quarter, denting economic output.

Mantashe said his ministry wasn't a lobbyist for any power source and that nuclear would have to compete for a place in the energy mix.

He said coal, which South Africa burns to generate most of its power, was still a "huge asset" and that officials needed to carefully manage a transition to using cleaner power sources such as solar and wind.

"You can't just jump from one extreme to the next one," Mantashe said. "If you switch off all coal-fired power stations in the hope that you will have renewables you will plunge the country into darkness."