THE decision about where to build Australia's first nuclear waste dump will be based on science, says Prime Minister Kevin Rudd.

Environment Minister Peter Garrett last week denied the government was going to  "fast track'' the waste facility.

He also said it would stick to its promise to repeal Howard-era legislation, which paved the way for the dump to go ahead in the Northern Territory.

Four sites are under consideration in the Northern Territory including Muckaty Station about 120km north of Tennant Creek, which was nominated by the Northern Land Council.

Three commonwealth defence sites are also in the running - Harts Range and Mt Everard near Alice Springs and Fishers Ridge near Katherine.

Asked in Darwin today if the new government had backflipped on its promise to Territorians, Mr Rudd said science would determine the dump's location.

"There is an independent scientific process underway and we will respond to the science on these questions,'' he told reporters.

"I think it's important again to take the politics out of this and to make sure that any advice to government is based on science.''

Consultants are due to report back to the government by the end of the month and Mr Rudd said the key to their scientific studies was geology.

"One element to that is what is the most geologically stable site but we will wait for the independent process,'' he said.