The cost of Pebble Bed Modular Reactor's (PBMR's) demonstration plant and pilot fuel plant had almost doubled to R31-billion as a result of inflation and higher materials costs, company chief executive Jaco Kriek said last week.
Kriek said the demonstration reactor, which would generate 200 megawatts of heat and 80MW of electricity, was now expected to be commissioned by 2018 - four years later than previously expected.
The plant has yet to receive environmental clearance.
Lynette Milne, PBMR's chief financial officer, said the cost of the demonstration plant had risen to R27bn and the pilot fuel plant could cost R4bn. It was envisaged that 80 percent of the R27bn could be sourced from the local market, she added.
Kriek said that funding was PBMR's "biggest constraint especially as government income has dropped".
The pebble bed modular nuclear reactor project, which was started in 1999, has spent R8bn of its R9bn budget, which runs to March next year.
Public Enterprises Minister Barbara Hogan said PBMR's funding was being looked at.
PBMR would help create a "strong nuclear base" in the country, she added.
Eskom and the Industrial Development Corporation hold an 85 percent stake in PBMR and the remainder is held by US-based Westinghouse.
The design of the reactor is set to be completed by the middle of 2011 and the funding for the demonstration plant will be organised after that.
Milne said a third of the R27bn could be funded by major users of energy. PBMR had spoken to PetroSA, Sasol and ArcelorMittal South Africa in this regard.
Nothemba Noruwana, a Sasol spokeswoman, said: "Sasol is in contact with PBMR Sasol does not, however, currently have any formal relationship with the pebble bed project."
Neither Thabo Mabaso, a PetroSA spokesman, nor Sven Lunsche, an ArcelorMittal South Africa spokesman, were able to comment.
Another third of the funding could come from foreign interests and the last third would be raised by debt funding.
Kriek said the credit crunch had caused PBMR to revise its business model. The company could largely give up its role as a nuclear technology developer and instead become "Eskom's nuclear division" to avoid losing the nuclear skills it had built up.
PBMR has about 920 staff and has annual expenses totalling R1bn.