A team of experts from the International Atomic Energy Agency (IAEA) left South Africa on Thursday after examining security at South Africa's nuclear plants.
Their visit followed the incident on November 8 when two armed groups tried to break into the Pelindaba nuclear facility near Hartbeespoort Dam.
One group exchanged gunfire with a security patrol but was driven off. Another group of at least four breached the complex's security fences, disabled a multitude of security measures and stormed the plant's emergency control centre.
There they stole a computer and tried to reach the control room, where they shot and injured station commander Anton Gerber.
Abdul Minty, South Africa's representative on the IAEA, invited the team to South Africa "to exchange views on the lessons learnt" from the incident.
Sources at the IAEA said the experts would thoroughly investigate security measures at South Africa's nuclear plants. But they appear to have left satisfied.
Necsa spokesman Chantal Janneker said the team found that the facility was "taking appropriate actions which they could not add to; that no nuclear installation was [ever] under threat; that Necsa provides adequate protection for its nuclear installations; that Necsa has good practices in respect of its security system that should be shared with [other IAEA members]".
But the national nuclear regulator has recommended that Necsa increase patrols, rotate staff in the control room and clear vegetation at the site to improve visibility.
"The NNR remains concerned about the situation and has . directed Necsa to implement additional security measures and undertake a comprehensive review of all current security provisions," said spokesman Phil Nkwashu.
"The NNR will work jointly with the National Key Points Authority and SAPS to periodically assess the adequacy of the Necsa security upgrades.
"Furthermore, similar oversight measures will be undertaken at other South African nuclear facilities where it is deemed necessary."
Nkwashu said the evidence his agency had examined "points to negligence on the part of some of the Necsa security personnel".
Immediately after the attacks Necsa suspended a group of security personnel, including the manager, until it had completed an investigation.
"Necsa has initiated disciplinary action against the staff members concerned," Nkwashu said.