Is nuclear energy banned in Australia?

Answer

Yes.

It's more complicated than that though. 

Firstly, it is important to understand that there is not a single ban on nuclear energy but MANY at both a federal and state/territory level which in addition to prohibiting the construction of civil nuclear power reactors also encompass other stages of the nuclear fuel cycle. 

Federal bans

Despite energy being a state (not federal) responsibility, in the late 1990's two separate prohibitions on nuclear energy were passed in parliament both under the Howard Government.

1) Radiation Protection Act

  • When was it brought into law?

    • 5th February 1999
  • What does it ban?

    • The Act prohibits the construction or operation of nuclear facilities including a nuclear power plant. There are more explicit restrictions in 'Part 5 Division 1—Prohibitions' (READ HERE) in the Act. 
2) Environment Protection and Biodiversity Act 

  • When was it brought into law?

    • TBC
  • What does it ban?

    • The Act prohibits the approval of the construction or development of nuclear installations including a nuclear power plant. 

State & Territory bans

  ACT
TBC
  New South Wales 

Uranium Mining and Nuclear Facilities (Prohibitions) Act 1986 No 194:

The Act prohibits the mining of uranium, construction of a nuclear facility (including a nuclear reactor and storage facility) and the operation of nuclear reactors to generate electricity. 

  Northern Territory 

Nuclear Waste Transport, Storage and Disposal (Prohibition) Act 2004:

The Act prohibits the construction and operation of a nuclear waste storage facility and the transportation of nuclear waste into the territory. 

  Queensland 

Nuclear Facilities Prohibition Act 2007:

The Act prohibits the construction and operation of a nuclear facility and connection of a generating power plant to supply the electricity network. 

  South Australia

Nuclear Waste Storage Facility (Prohibition) Act 2000:

The Act prohibits the construction or operation of a nuclear waste storage facility and the transportation of nuclear waste in the state. In addition it stipulates that no public money should be used to encourage or finance nuclear waste storage facilities and that public inquiries must be conducted if the Commonwealth approves a nuclear waste storage facility in South Australia. 

  Tasmania 
TBC
  Victoria 

Nuclear Activities (Prohibitions) Act 1983:

The Act prohibits the exploration of uranium or thorium, mining of uranium or thorium, radiometric surveys, constructing or operating a nuclear reactor, storage facility and various other nuclear fuel cycle related facilities and possessing nuclear material.

  Western Australia 
TBC

What other countries have bans on nuclear energy?

Australia is the only member of the G20 with a ban on nuclear energy.

Sources:

ARPANSA, Legislation.gov.au, Legislation.sa, Legislation.vic, Legislation.qld, Legislation.nsw, Legislation.nt,