Correctional Services said that “matters are under control” at Johannesburg’s Sun City Prison on Wed.
The Nuclear Energy Corporation of South Africa (Necsa) has fired three of its security staff because guards were sleeping on duty while two bands of armed men broke into Pelindaba last year.
One manager resigned, and a manager and supervisor responsible for the guards received lighter sanctions.
Pelindaba, near Hartbeespoort Dam, the site of the small Safari-1 reactor, is the vast fenced-off headquarters of Necsa and nerve centre of the country's nuclear industry.
This is where the apartheid regime used to develop its nuclear weapons and uranium refinery, and remains one of the most heavily guarded national key points.
But shortly after midnight on November 8 last year, two armed bands tried to breach the facility's security fence. One group was driven off after a shootout with a guard.
The other cut through the 30- strand 10000-volt electrified fence, disabled other sophisticated security systems and broke into the emergency control centre.
There they attacked station commander Anton Gerber and shot him through a lung. He summoned help and they fled.
Necsa immediately suspended the security staff who were on duty that night and their managers to determine how the country's most sophisticated security system was breached.
Exhaustive investigations led to a series of disciplinary hearings, which determined that the attackers were caught on closed-circuit television, but that the two guards monitoring the system were fast asleep.
They were fired along with their shift coordinator. The shift supervisor was suspended without pay for eight shifts.
The manager of security services resigned rather than face a disciplinary hearing and his general manager was demoted to a non-executive position.
Gerber spent weeks in intensive care, but returned to work at the beginning of the year.
The International Atomic Energy Agency recently sent a team of specialists to probe security at Pelindaba. They gave the facility a clean bill of health and plan to introduce features of its systems at other nuclear plants around the world.