Noisy protesters are targeting a global nuclear conference in Sydney, saying they want attendees to know they are not welcome.

About 60 people from a group calling itself the Sydney Anti-Nuclear Coalition were on Wednesday demonstrating in front of the Elizabeth Street hotel playing host to the World Nuclear Fuel Cycle conference.

The coalition is mainly made up of environmental, student and trade union groups.

Police dragged several protesters away after they tried to get into the building and ordered the demonstrators to move on, but made no arrests.

The conference is a nuclear fuel industry event, held annually at different locations around the world.

Australian Conservation Foundation spokesman Dave Sweeney played down the scuffles and praised the group for braving the wet weather to turn out.

"It's been a bright and bouncy protest. It's had a bit of passion as it should, because there's high stakes here," he said.

"There are people here from Perth, from Melbourne and the Northern Territory and nationally there is a very deep concern about all things nuclear in Australia."

Mr Sweeney said arguments that nuclear fuel was a green alternative to coal power were not acceptable.

"You can't call an industry that creates a waste that's a carcinogen for 250 million years clean or green," he said.

"It (nuclear energy) is not going to ride over the hill as a white knight and save us, it's not a solution to climate change.

"It's expensive and linked to the worst weapons and the worst waste."

Greens Senator Scott Ludlam said it was important for people to voice their concerns about nuclear energy.

"The nuclear industry needs to know that wherever they set foot in Australia, we'll have a presence," Mr Ludlam said.

"Sometimes it's important to just confront them and let them know they're not welcome here."