The former admiral overseeing South Australia's nuclear inquiry says he is trying to be as straight as possible on what can be a divisive issue, but some concerns about the nuclear industry go too far.

Kevin Scarce, who was appointed by South Australian Premier Jay Weatherill this year to investigate if South Australia should go into nuclear enrichment, storage of waste and power generation, says he is on target to deliver preliminary findings by February before a final report by May.

He says he is focused on objective evidence and tapping into global expertise, and accepts that many people have passionate views about the nuclear industry.

A US expert told the nuclear inquiry a recycling plant for spent nuclear fuel could cost around $6 billion. Glenn Campbell

"Some of those concerns are overheated," he told AFR Weekend. "I think it's really important that we investigate all the issues and rely on fact-based evidence."

Mr Scarce, who was governor of South Australia for seven years until mid-2014, has taken evidence from more than 60 witnesses. The latest on Friday was Eric Loewen, the chief consulting engineer at United States firm GE Hitachi Nuclear Energy.