Eskom defends Koeberg safety after four contamination events

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JEREMY MAGGS: Four radioactive contamination events at Koeberg in just over two weeks are raising fresh questions about safety at South Africa’s only nuclear power station.

Eskom and the nuclear regulator insisting that no radioactive material escaped into the environment, that nearby communities were never at risk. But repeated failures during maintenance, I think, does demand closer scrutiny.

In that respect, I’m going to talk now to Velaphi Ntuli, who is Eskom’s chief nuclear officer. Velaphi, a very warm welcome to you. So four contamination events in little more than two weeks, why should South Africans believe that Koeberg is safe?

VELAPHI NTULI: In an outage, we perform over 20 000 activities and a limited number of those result in a localised airborne radioactivity. So it is expected. It is not something that is not expected.

Such activities, we plan for them appropriately, and we have diverse mitigations that we put in place to ensure that we manage the airborne radioactivity properly. To ensure the safety of our workers, public and environment.

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I would like to assure you and assure the South African public that there was never an instance when the airborne radioactivity material was released to the environment, as our containment is purposefully built to keep all the material inside containment because it’s under negative pressure.

There are slightly elevated levels of radiation that we have seen and I’m happy to [speak about] each one of them. But broadly, the slightly elevated and localised level of radiation that we have seen.

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Only four workers were exposed between 11 and 20 microsieverts, and you contrast that to 20 000 microsieverts, which is our annual limit.

It’s about 100 microsievert that you would get if you have an X-ray and about 400 microsieverts if you have a mammogram.

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So what am I trying to say? I’m not trying to minimise that we did have an elevated or slightly elevated radioactivity, but it was well within what the limits are, and it is [in] the course of business. So I don’t want to leave a perception out there that is alarming.

JEREMY MAGGS: Could I ask this, and you’ll correct me if I’m misinterpreting it, but the repetition, does it point to a deeper failure in maintenance, planning or safety controls?

VELAPHI NTULI: There was no repetition. If you can allow me, then I can go through the incidents. The first incident on 30 June that’s been spoken about as an incident, it was not an airborne radioactive incident.

When we work in containment, we are issued with what we call electronic personnel dosimeters (EPDs). Those are programmed for two things – the intensity of radiation and the amount of those that you get in containment.

So one of our workers, and we know that there are hotspots within containment where if you get closer to that hotspot, you pick up a higher radiation dose, then you have to move away. So that was the alarm that happened. So that incident really has nothing to do with airborne.

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The second incident is the one that has to do with airborne where one of our portable ventilation systems became defective, the power cord became bent. Therefore, there was a slightly elevated airborne incident. There were 31 workers in containment at that point, which we withdrew, and we tested them and their levels were low.

Then the third incident that I’d also like to mention. Well before, we have monitors that are monitoring, and well before we saw an increasing trend, the workers were withdrawn.

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And why is that happening?

Because we know that we expect this, the activity that we are doing, we know that it induces this and therefore we stop work and withdraw [workers].

Then the last incident, exactly the same. You can’t say when you stop driving your car while the oil life of the car is still 40% and you say the oil has failed. So because we knew that this was coming, the levels are getting high, we stopped the activity, they subside, and then we continue working. So it’s not a failure or any incident at all.

JEREMY MAGGS: I do understand; it does clarify it. In spite of the mitigation that you’ve outlined to me, though, do these events raise any questions, in your opinion, about granting Koeberg another 20 years of operation?

VELAPHI NTULI: No, it does not. The reason that I would say that is the activity that has led to these increased levels, as I said, is expected. It is done when we do our steam generated Eddy Current Testing. That is a worldwide activity that nuclear power plants like ours do. These measures that we put in place are exactly the same.

So maybe you might ask the developer what is different, we never had this two years ago.

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What is different in this case is that we have just put in these new steam generators and the work that it takes for you to put in these steam generators, it has shown that the cycle after you have put in the steam generators, you have a bit more activity in your primary system than normally.

So after a few cycles from now onwards, our primary system will be more and more cleaner, for the lack of a better word, and these levels of activity will then subside.

JEREMY MAGGS: Could you explain to me how this entire series of events is being investigated? Because it would raise the question about whether Eskom itself can objectively investigate its own safety performance?

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VELAPHI NTULI: Absolutely. Maybe just to give you a view as to how we work at Koeberg. Any event that happens, we raise what we call a condition report. The regulator has access to all of these things that we raise, and they then independently do their view.

If they want more material, they will come to us and say they need this, but they have access to where all this information is documented. So they will continue to investigate and do their investigation.

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Internally we have independent organisations that will then have a look, independent of the main groups that are involved, do an internal independent investigation.

Then lastly, we belong to an organisation that is called World Association of Nuclear Operators. We report on this, they will ask for reports, and they will do an independent review.

Then any nuclear incident is rated on an Ines (International Nuclear Event Scale). So that’s a scale that we use for any incident from Fukushima, from Three Mile Island, to what we have to say, where is it [on the scale]? This registers as zero, meaning that it is non-consequential. It’s minor.

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I’m sure that everyone, that once they’ve looked at this, they will come back to the same conclusion. So we are very transparent and open for that scrutiny.

JEREMY MAGGS: Thank you very much indeed. That is Velaphi Ntuli, who is Eskom’s chief nuclear officer.

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