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Nuclear: ASN able to evaluation its strategies to increase reactor life

Posted Jan 23, 2023, 10:45 AMUp to date on Jan 23, 2023 at 10:54 am

EDF has by no means produced so little nuclear electrical energy. Why was it important to close down so many reactors in 2022?

Typically, within the spring and till the start of autumn, there may be a lot of reactors that are shut down for routine upkeep operations, that is a part of the traditional operation of the commercial instrument of EDF. Added to this had been the consequences of the foremost refit operations determined by EDF to cope with the passage to 40 years of the French nuclear fleet. These operations are a lot heavier than standard upkeep operations and can proceed for an additional 15 years. There was additionally the delay impact in upkeep operations generated by the Covid interval. These operations had been rescheduled over the next three to 5 years. Added to this was the fully sudden phenomenon of stress corrosion on the protection injection circuits. Corrosion is commonly put ahead however that doesn’t clarify the truth that half of the reactors had been shut down a number of months in the past.

This occasion nonetheless participated within the exhibition of electrical energy payments in France and Europe. Wasn’t France too choosy about these “microcracks”?

Stress corrosion cracking develops over time. We might be on the very starting of the phenomenon, with a micro-tissue, or far more superior, with extra vital cracking that’s spreading. What we found had been actual cracks that might attain a 3rd of the thickness of the pipes. The sizes of those faults had been generally on the restrict of the extent which might result in a sudden rupture of the pipes within the occasion of tripping of this circuit.

The sizes of those faults had been generally on the restrict of the extent which might result in a sudden rupture of the pipes.

This circuit permits the reactor core to be cooled within the occasion of a breach within the main circuit, so we might have discovered ourselves in a state of affairs the place the protection injection circuit would have been triggered and, due to the scale, cracks would have damaged. . On this case, we might have been confronted with a nuclear accident with the potential for releasing radioactive materials into the surroundings. The reactor would in all probability have been misplaced. It’s subsequently a severe topic by way of security which has been handled significantly by EDF by way of accountable selections to close down sure reactors to be able to perceive the phenomenon, decide its extent and outline an motion plan.

With the development of applied sciences, is there not a danger of discovering an increasing number of faults in our nuclear energy stations?

Don’t be mistaken, it’s not as a result of one is extra demanding that one has discovered stress corrosion. The management applied sciences which enabled EDF to suspect an unprecedented phenomenon had been the identical as these applied beforehand.

After we see the reason given by EDF on the preponderant reason for the event of this phenomenon, we notice that it’s particular to France since these are reactors with altering pipe geometries in comparison with the preliminary Westinghouse design. , which favors this phenomenon. Furthermore, in France, the 900 MWe reactors, the oldest, conforming to this preliminary design, are usually not or are little or no affected by the phenomenon. If the Individuals don’t discover stress corrosion it’s not as a result of their management authority is much less demanding or as a result of their management strategies are much less refined, it might be as a result of their pressurized water reactors have a unique design. .

Emmanuel Macron pleads to increase the lifetime of French reactors past 50 years. RTE’s eventualities even define an extension past 60 years. Is it practical?

We completely want to look at this topic in depth, with out taboos, with at the very least ten to fifteen years upfront. It’s vital to have the ability to query the potential working lifetime of reactors with regard to questions of safety, given the justification strategies which can be at the moment accepted in France. It’s vital to take a look at the delicate parts on which there’s doubt as a result of they aren’t replaceable. That is the case for the tank and the enclosure. There are additionally parts which can be very tough to exchange, given the chance of publicity to radioactivity of the operators to take action, that is the case of the molded elbows that are mounted to the reactor vessel. For these parts, there could possibly be a constraint within the continuation of operation, even perhaps earlier than 50 years. It’s subsequently essential to ask the query upfront so as to have the ability to act accordingly.

When will you be capable to submit an opinion on this matter?

We wish to take a place by the top of 2026 on the potential continued operation of French reactors past 60 years. We’re preserving the ten-year evaluation course of however on the identical time, we’re going to venture ourselves past this on a restricted variety of parts for which we wish to ask ourselves how far is it fairly attainable to proceed operation. We’re taking a step forward as a result of the same old ten-year interval shouldn’t be tailored to the wants of anticipating the attainable penalties of the top of lifetime of a reactor. That is what the Individuals are doing. They issued working licenses as much as 40 years, then 40 to 60 years and now for some reactors they go as much as 80 years.

How do they handle to have far more productive and far more sturdy reactors than these put in in France?

There are numerous variations however primarily the strategies of justification utilized in the US to outline the lifetime of a reactor are usually not the identical as these we use. The Individuals use probabilistic approaches whereas we’ve got deterministic approaches to justifying security. The Individuals settle for very low likelihood default eventualities. This isn’t our case.

Bernard Doroszczuk, president of the Nuclear Security Authority.DSC

Might we imitate them?

I went to the US lately to debate this topic with my counterpart (the NRC) in addition to with EPRI – the joint analysis group of American nuclear operators. We determined to have technical exchanges with them to see what strategies of justification are utilized in the US to be able to see in the event that they could possibly be accepted in France.

However earlier than we get to that time, we’ve got to come back to a zero level: that’s to say, decide the foreseeable working lifetime of the reactors beneath secure circumstances in view of the present justification strategies, then outline the ideas of the brand new strategies of justification which might, if vital, be applied. EDF must present us with a substantiated file on this topic by the top of 2024 for an ASN place assertion by the top of 2026.

Along with the extension of current reactors, the chief is relying on the revival of nuclear energy. To what extent is that this credible given the very robust pressure that already weighs on assets within the sector?

The query of assets is the primary subject. This system that’s envisaged is out of the bizarre in comparison with what has been executed over the previous twenty years. This, at a time when there was a lack of abilities within the sector and a lack of expertise within the conduct of main tasks. For 20 years, not one of the main nuclear tasks has gone as deliberate. Whether or not it is the EPR, the CEA’s RJH venture, or the ITER venture. That is one thing that we discover in all Western nations which have skilled the identical lack of expertise as a result of absence of nuclear tasks.

EDF has once more simply postponed the start-up of the Flamanville EPR in order that the alternative of the reactor vessel head that you’ve prescribed will happen barely a number of months after its start-up… Should not this tools be modified earlier than to start out up ?

On the finish of December, we acquired a request from Framatome to postpone the alternative date for this cowl. Initially scheduled earlier than the top of 2024, Framatome is asking us to postpone this obligation till the top of a primary full working cycle, i.e. round mid-2025. We’ll examine this request.

The senators who’ve simply adopted the nuclear acceleration invoice are fearful in regards to the results of world warming on our energy stations. What’s it actually?

We now have determined to combine the topic of world warming into the reflection that we’ve got launched on the extension of the working life past 60 years. At this time we’re taking a look at this topic in 10-year increments, on the event of the critiques. We’ll ask EDF to plan for the long term, utilizing IPCC information to find out the weak factors and combine the buildup of potential impacts on a territorial scale, for the fleet in service and the brand new installations envisaged.

What are the important factors?

There are questions of safety and problems with influence on the pure surroundings. When it comes to security, the licensee should be sure that the air temperature within the premises doesn’t exceed the utmost allowable temperature of the tools important to security, and that the reactors have always enough water to chill fuels. Since these phenomena are comparatively sluggish and predictable, the operator can handle them by decreasing the ability of the reactors or by shutting them down.

When it comes to influence on the pure surroundings, the drop within the circulate of the watercourse may have an effect on the dispersion of effluents from the reactors and might result in an increase within the temperature of the water above the licensed thresholds, after discharge. cooling waters. Which means EDF has to extend its on-site effluent storage capacities.

As occurred this summer time for the primary time since 2003, within the occasion of a necessity for electrical security and an crucial of public necessity in distinctive circumstances, one-off exemptions could also be granted by ASN. Lastly, as water warming phenomena are prone to improve, this might suggest the necessity to set up much less water-intensive cooling techniques. However right here once more it takes time and it requires anticipation.

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