The National Nuclear Regulator has been given permission for the United States' nuclear-powered aircraft carrier Theodore Roosevelt to drop anchor in Table Bay.
The approval was granted over objections from environmental group Earthlife Africa, which has said it plans protests against the vessel.
The 332 metre carrier is expected to arrive in Table Bay on Friday on a courtesy visit, at the invitation of the SA Navy.
A spokesperson for the regulator, Tim Hill, said on Wednesday that the license granted for the visit obliged the applicants - the SA and US navies- to observe safe operating procedures.
It also called for an emergency plan devised by the city of Cape Town to be operational.
Hill said though the license allowed the regulator to monitor the environment around the ship for radiation, it would likely rely only on existing detectors set up to monitor Koeberg nuclear power station, a few kilometres north of the Roosevelt's planned anchorage.
The vessel would lay up in the middle of Table Bay, he said.
The license covered the period Oct 1 to 10.
Hill said liability in case of an accident was governed by the provisions of the National Nuclear Regulator Act.
He believed this would be the first visit to Cape Town by a nuclear-powered vessel since the German cargo ship the Otto Hahn in the 1970s.
Nuclear-powered submarines from the British navy had however visited Simonstown.
The carrier, built in the early 80s, carries a crew of about 3 200, with another 2 480 members of the air wing, plus 85 aircraft.
She first saw active service in the US' 1991 Operation Desert Shield, dropping over 4,8-million pounds of explosives. -Sapa