After the radioactive leaks from an EPR reactor in China, EDF wants to be reassuring

It was considered, with its twin installed on the same Taishan site, 120 km from Hong Kong in southern China, as the symbol of French nuclear technological success. The construction of these two EPRs started in 2009, well after the start of the Flamanville project (Manche). Their commissioning was carried out in December 2018 (for reactor number 1), and in September 2019 (for number 2), while their French cousin is still not completed. However, this “success story” today seems to have uranium in the wings. A radioactive leak was indeed detected on one of the cooling circuits.

In 2020, the number one EPR reactor at the Taishan power plant was shut down to reload new fuel.

During this manipulation, abnormally high concentrations of certain rare gases, mainly Xenon and Krypton, were detected in the water of the primary circuit, which circulates in the reactor, and is therefore in direct contact with the fuel.

This leak does not represent a direct danger

"Too large a quantity of these gases is the sign of a leak, or even a rupture of one or more rods in which the fuel pellets are stacked", analyzes Yves Marignac, nuclear expert and spokesperson for the negaWatt association.

Directly, this leak does not represent a danger because the primary circuit operates completely closed.

"There has always been radioactivity in the primary circuit," confides an internal source to the nuclear production department at EDF.

In France in the 1970s, we shot up to 500 becquerels per ton (Bq / t) of water.

Which was a lot.

The rods were not waterproof enough to contain all the radioactivity of the fuel they contained.

Today, their design by Framatome, a subsidiary of EDF, has greatly improved and the radioactivity no longer exceeds 100 Bq / t of water.

Beyond that, we systematically shut down the reactor.

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A lot of worry

Why then is the information of such concern? We never replace all of the fuel during a reloading, but only a third. In the case of Taishan 1, damaged ducts were therefore undoubtedly reintroduced, since the leaks continued after the reactor was restarted in October 2020. In China, the maximum threshold for radioactivity in the primary circuit was set at 150 Bq / t water. However, according to our information, the new measurements indicated quantities of between 250 and 300 Bq / t. In order not to interrupt the operation of the reactor, the Chinese safety authorities have therefore decided to increase the threshold to… 324 Bq / t, ie more than three times the French standard!

The concentrations of radioactivity could have been much higher.

But the plant operator, China General Nuclear (CGN) has taken care to release it into the atmosphere.

“The gaseous effluents are effectively collected and then discharged, however after a decrease in radiological activity for several weeks, details EDF.

These releases were carried out in compliance with current Chinese regulations.

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The French EPR once again questioned?

The French electrician is visibly uncomfortable in this story. He had known about the problems for several months. The information was finally revealed by the American channel CNN on Monday. The management does not hesitate to refer those who ask questions that are too embarrassing to its subsidiary Framatome, itself to absent subscribers. If the leak is linked to a design flaw in the pencils, it is indeed she who will have to be directly accountable.

On the other hand, if their tightness has been compromised during operation, by excessively high power, temperatures or pressures, then EDF's entire design of the EPR would be called into question. That of the two Chinese reactors, but also the four others currently under construction: at Flamanville, at Olkiluoto in Finland, as well as at Hinkley Point in Great Britain.