Starting next Friday, reactor 3 at the Oskarshamn nuclear power plant is planned to be shut down for nine days for repairs.

The effect on the electricity price risks being large, says Christian Holtz, electricity market analyst.

- If we look at what the meteorologists are forecasting, severe winter weather is on the way.

When it gets colder and electricity use increases, every megawatt that disappears from production has a greater price effect.

And he gets agreement that the timing is unfortunate from Carl Berglöf, nuclear power expert at Energiföretagen.

- During the period when Oskarshamn 3 is closed for repairs, we will only have one functioning reactor, Ringhals 3, south of Stockholm.

The system becomes fragile when we lose both production and transmission capacity.

Several reactors are idle

Oskarshamn 3, which is now to be repaired, is the largest reactor in Sweden and accounts for about a third of Sweden's nuclear power generation, or just over 8 percent of Sweden's electricity supply, according to the owner company OKG.

The planned shutdown comes at the same time as two other large Nordic reactors are also not delivering electricity.

Ringhals 4 is out of service until January 31 following an incident where the pressure cooker was damaged in a test.

In addition, the new Olkilouto 3 reactor in Finland, which is the Nordic region's largest single electricity producer, was supposed to be put into commercial operation on December 27, but the start has been postponed until January 22 after cracks were discovered in feed pumps in the turbine hall.

Can be "really high prices"

And it is not just the temperature that will now determine electricity prices.

- If there are also weak winds, it will be possible to have really high prices, says Christian Holtz.

How much higher the prices will be is difficult to speculate, according to Holtz.

- It is an already strained situation.

The price effect will be much greater now in December than it was in mid-November, for example.

At the same time, Carl Berglöf at Energiföretagen points out that it is still good to have a planned repair stop.

Otherwise, the risk of an unplanned stop increases, which would be worse.

Now we just have to hope for "good electricity price weather", i.e. mild and windy, so that prices do not rise too sharply during the reactor shutdown.