The company said the power plant had just 15 days of fuel left to run the generators and would be switching part of the plan to a cold state to preserve energy supplies.

Meanwhile, seven ships carrying green have left from Ukraine's Black Sea ports a day after Russia rejoined a scheme to allow its export Moscow pulled out of the deal last week after an attack on its naval base in Crimea.

Well, let's go to keep now.

And our correspondent there, Catherine by hunger and Catherine, lots of development, lots of movements.

But let's begin with the apparition the nuclear power plant first.

Yes, the news that we're getting is that there was heavy shelling around this operation nuclear power plant overnight.

As a result, the main high power voltage lines bringing electricity to the facility were then knocked out.

And this means that the facility is now running on backup generators.

Now this is an extraordinary situation because this is europe's biggest nuclear power plant.

It's six main reactors have had to be shut down because of safety concerns, but it doesn't need constant supply of electricity to make sure that it doesn't go into a nuclear meltdown.

Now it has been knocked off the grid before that has happened and it has been reconnected.

Obviously this this incident does add to the international concerns about the safety of the facility and we've heard from the director general of the international atomic Energy Agency, Rafael Grossi.

He said that this incident underlines extremely precarious nuclear safety and security situation at the facility.

And he renewed calls for a protect protection zone around the nuclear power plant.

As you mentioned there further south at the in Ukraine's Black Sea ports, we've seen seven ships leave carrying nearly 300,000 tons of grain.

They're going to countries like Spain Italy and the Netherlands, Netherlands.

The fact that this grain initiative is continuing is positive news.

And we've seen global prices for food on the global stock markets going down again because of the positive developments in the Black Sea Catherine.

Thank you so much for that update.

I'm joined now by dr ross peel an expert on nuclear power plant security from King's College London.

Thank you dr Peale for joining us here on the program.

Mean, frankly, these nuclear power plants across Ukraine have been at the center of this conflict from the very beginning.

Yes, absolutely.

And thank you very much for having me.

These nuclear power plants have been a key objective, it seems, of the Russian invasion with we are seeing in the early days of the invasion, military forces moving very quickly to secure a variety of nuclear facilities.

And it seems now that the only one they've managed to hold on to is a poor Asia, although that's not it's all a good thing.

Help us understand, help our audiences understand this grid system and once they're turned off, you know, why do they need energy for?

How long do they need energy?

So nuclear fuel in a reactor, even when you shut the reactor down remains very hot and generates even more heat actually than it has at the start over time.

And so you need to continue to remove that heat in order to prevent the temperature rising to the point of being in danger.

Now that situation that heat generation will continue for quite a long period of time, it might initially be very hot and very high generating.

But it remains that way for for for a long time for years and years actually.

And once the grid is changed to say that the Russian system, does that mean that they can actually control which direction it goes in?

It does.

So if they've connected the power plant up to a Russian grid system instead of the Ukrainian grid system, then they will be able to send that power to perhaps not the Russian grid due to the distances involved and some of the infrastructural problems, but certainly to power Crimea and maybe into nearer parts of Russia.

And I suppose also control where it doesn't get it, especially with this kind of cold, harsh winter coming.

Absolutely.

So one of the key elements of this is presumably to prevent the energy being available to Ukraine in order to put pressure on Ukraine to surrender.

The interesting point though is the fact that they've kept the Ukrainian workers on.

Yes.

So the Ukrainian workers are there simply because many experts believe myself included, that Russia would simply not have the thousands of people necessary in order to operate a plant like this ready and waiting with nothing to do apart from go to Ukraine and do so.

Those people are already employed in running power plants in Russia.

And so Russia will certainly want to keep those Ukrainian staff working at the plant and operating it, albeit under new contracts that make them employed by a Russian organization that's been set up specifically for this purpose.

I understand this time around they've date stamped the time, how significant is this?

So this is not a new development.

The date stamping of something like this in public terms is potentially new, but it's always been the case that the diesel supply at the plant for the emergency backup generators is limited in some way.

And I've heard estimates ranging from as little as 10 days to as high as 40 days.

It depends to a certain extent on how, how much of the generation capacity is needed and how fast the fuel is used.

But certainly there is a limitation unless new diesel can be brought in via delivery, which under the conditions of conflict is challenging.

And speaking of the conditions of conflict, I mean, how dangerous can it be if running these systems falls into the wrong hands or the wrong thing happens at these nuclear power plants?

So it can be dangerous.

It can be catastrophic.

In fact, if we see that the nuclear material can no longer be managed safely and kept cool, either within the reactor or in the spent fuel storage areas outside of the plant itself.

Then we might see that fuel getting hotter and hotter and eventually breaking out of its various containment to release nuclear material into the atmosphere where it could travel great distances.

Okay, DR Peale will have to leave it there.

Thank you very much for joining us here on the program.

Thank you.