Production can resume at NTP Radioisotopes' Pelindaba facilities after receiving the go-ahead from South Africa's National Nuclear Regulator (NNR).

NTP's lutetium lab (Image: NTP)

Preliminary production runs at the NTP processing plant, which the company said had been "effectively" shut down since November 2017 following a series of "safety-related issues", will be followed by full production.

The shutdown was ordered by the NNR after NTP reported the discovery of procedural deviations related to a set of standard operating protocols. The incident did not present any physical risk to either NTP staff or the environment, and no safety limits were exceeded at any time, NTP said. The Safari-1 nuclear reactor was not affected by the shutdown.

Following the shutdown, an interim management and safety team appointed by NTP parent the South African Nuclear Energy Corporation (Necsa) instituted a number of process, procedural, and administrative changes to NTP's operations. Reduced production runs restarted in late February, but the plant was shut down again in May after additional "safety-related incidents".

Subsequent "changes and corrections" to enable the plant to return to production were subject to review and sign-off from numerous internal committees and the NNR, NTP said. South Africa's Minister of Energy, through Deputy Energy Minister Thembisile Majola, in September assumed direct oversight of the NTP Board. This, NTP said, was to "enable more efficient communication" between NTP, Necsa and and the NNR.

NTP produces and distributes molybdenum-99 (Mo-99) and radioisotope-based diagnostic imaging and therapy products including iodine-131 and lutetium-177. The company had previously been one of the four major global suppliers of the short-lived Mo-99, which is the world's most widely used medical isotope, and the shutdown has impacted significantly on the supply of medical radioisotopes both locally and internationally, NTP said.

"Our priority was to facilitate an uncompromised safe return to reliable supply of this active pharmaceutical ingredient from South Africa to the global nuclear medicine fraternity," Majola said on 16 November. While the NNR's processes were sometimes seen as time-consuming, they were essential to the outcome, she added: "The nuclear regulator's primary mandate is to ensure that all safety standards are met, so that we can achieve safe operating conditions."

NTP Group MD Tina Eboka said the extended shutdown was "unfortunate" but also an "extremely valuable lesson" for the group. "Ultimately it has strengthened our working relationship and appreciation of the role of the regulator, and it has without a doubt strengthened our corporate safety culture," she said.

NTP Group describes itself as the largest contributor to South Africa's state nuclear revenues. The company said it must now rebuild customer trust and regain lost business.

"Before the shutdown we were a profitable ZAR1.3-billion (USD93 million) turnover company," Eboka said. "Right now, we need to focus on returning to those levels of success as quickly and as reasonably possible and position NTP for sustained growth over the medium term."