Can French nuclear reactors function past 60 years? To seek out out, the tricolor nuclear policeman intends to presumably draw inspiration from American strategies. ” We want to enrich ourselves with experiences overseas and particularly with People “, stated Monday, January 23 Bernard Doroszczuk, the president of the Nuclear Security Authority (ASN), in the course of the presentation of needs to the press.
The response have to be supplied as shortly as attainable to offer visibility to the sector and supply key components for the definition of French vitality coverage. ” Some vitality situations [notamment le scénario N03 établi par le gestionnaire du réseau de transports d’électricité RTE dans le cadre du rapport Futurs énergétiques 2050, ndlr] contemplate the continuation of the reactors as much as 60 years, and even past. Nonetheless, these situations solely make sense if they’re accessible. In any other case they are going to get us in bother “, factors out Julien Collet, deputy director common of the ASN. “We should estimate the related calendar deadlines in order that the vitality coverage is in step with the protection limits”he provides.
The nuclear policeman desires EDF to look significantly on the situation to be able to present an in depth file by the tip of 2024. “We wish to see this deadline included within the subsequent PPE [programmation pluriannuelle de l’énergie, ndlr] “, specified the president of the authority of management. ASN then intends to look at this detailed file with the assist of IRSN, its technical arm, to undertake a place by the tip of 2026 on the newest.
A Break in Doctrine
Presently, French nuclear reactors are usually not related to any lifetime. Nonetheless, the protection calculations on the elements have been carried out for 40 years. Subsequently, the extension of their operation past this deadline is topic to a management evaluation, which takes place each ten years: the well-known ten-year inspection. In concrete phrases, this evaluation has two elements. The primary consists primarily of guaranteeing compliance and management of ageing phenomena. The second, to extend the extent of security by approaching as a lot as attainable the protection goals of the EPR, which is a 3rd technology reactor. As soon as the examination has been handed, the reactor is thus licensed to function for one more ten years.
However in parallel with this doctrine rooted within the ten-yearly outages, ASN now needs to develop a extra forward-looking strategy, to be able to decide how far it will be attainable to proceed working the reactors. An ideal first within the philosophy of the nuclear policeman.
” The ten-year interval just isn’t appropriate for anticipating with adequate deadlines”, defined Bernard Doroszczuk. ” We’re enterprise in-depth work on the prospects for going past 60 years “. This work will probably be carried out initially with the calculation strategies at the moment in power in France, however the nuclear policeman additionally desires EDF to look into the usage of different strategies, particularly some utilized in america.
“Relying on the boundaries that we’ll encounter, we may ask ourselves the attainable query of fixing the strategies of justification [comprendre des méthodes de calcul, ndlr] that we use to know whether it is attainable to transcend. For this, we’ll draw inspiration from the strategies used overseas and particularly in america, which have a sure lead on this topic over France. A totally regular advance for the reason that American nuclear fleet was constructed 10 to fifteen years forward of the French fleet,” defined the President of ASN.
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In the direction of extra flexibility in calculation strategies
The query of the event of strategies arises particularly for estimating the lifetime of the vessel, which is an irreplaceable factor and which subsequently determines the lifetime of a reactor.
“The tank turns into fragile below the impact of irradiation. The properties of the steel degrade over time till the mechanical properties are too degraded to permit continued operation,” explains Julien Collet.
Within the mechanical calculations applied for this estimate, France requires that the best defect be taken into consideration on the most penalizing location. An strategy described as standard. The People favor a probabilistic strategy: they calculate a chance of distribution of defects within the supplies.
The bodily phenomena used within the calculations are additionally not the identical on both facet of the Atlantic. Presently, France doesn’t embody doubtlessly favorable phenomena in its calculations. For instance, if a crack seems inside the fabric of the tank, it might propagate to the outer pores and skin. It then turns into by means of. However, because the crack propagates, it can encounter hotter and subsequently softer materials, which may doubtlessly cease the crack. “It’s a acknowledged speculation in sure calculation strategies in america, however not in France”factors out Julien Collet.
However at present, the nuclear policeman says he is able to raise “a sure variety of conservatisms”. The target is to establish “what flexibility could possibly be obtained within the mechanical calculations of the tanks with out calling into query the extent of security”, assures the deputy common supervisor.
With this in thoughts, ASN groups lately traveled to america to satisfy their counterparts from the Nuclear Regulatory Fee (NRC) in addition to members of the Electrical Energy Analysis Institute (EPRI), a analysis institute specializing in electrical manufacturing from america.
“What stands out very clearly is that there’s a lot of convergence between France and america on essentially the most delicate topics and the best way to strategy them,” argued Bernard Doroszczuk.
US energy vegetation are ageing much less shortly
Nonetheless, an vital factor have to be taken into consideration: the American energy stations don’t age fairly on the similar charge as their tricolor counterparts. As a result of in america, atomic vitality works “in base”. In different phrases, the reactors produce electrical energy constantly, with out giant variations in energy.
” It is extremely completely different from France, the place nuclear manufacturing fluctuates enormously. When demand may be very low, particularly at evening, or when the wind generators partly take over as a result of there may be wind, EDF reduces the sail space “, explains to The gallery Tristan Kamin, nuclear security engineer.
And this phenomenon, known as “modulation”, just isn’t with out penalties. Like a ” automotive motor ” who “ desire to all the time run on the similar pace “, reactors subjected to robust temperature variations” are extra burdened mechanically “, we clarify to the ASN. This inevitably results in fatigue, and, subsequently, quicker put on of sure elements. On Monday, Bernard Doroszczuk himself talked about this downside: With the cessation of controllable manufacturing of fossil origin, […] fluctuations in electrical energy demand must be absorbed by the nuclear fleet. The query is: does this result in specific results when it comes to extending the fleet? “, he launched.
Modulation limits security margins
Particularly for the reason that topic just isn’t restricted to the wear and tear of elements and their attainable substitute. Certainly, these fluctuations additionally cut back the protection margins that apply in France. Concretely, a sudden improve within the energy of a reactor causes very excessive neutron fluxes in its major circuit. Nonetheless, if an accident happens at this essential second, the influence on the tank will doubtlessly be very vital “, Underlines an EDF engineer who requested anonymity.
End result: ASN should calibrate its security guidelines to this state of affairs. of worse which additional will increase the necessities for the extension of the fleet. ” Whereas People should not adapt to it! They subsequently have far fewer variables to take note of when deciding on the lifetime of a plant. “, insists the EDF engineer.
On the topic, the British have additionally taken the identical path as throughout the Atlantic:
“When EDF offered its EPR in England, the corporate additionally proposed its mode of management, that’s to say the potential for commonly various the ability of the reactor. However the English stated they did not wish to use it that manner, in order to not cut back their security margins, ”he continues.
Get impressed by taking disparities into consideration
Below these situations, ought to we additionally restrict the modulation of the fleet in France, to be able to protect the tricolor energy stations as a lot as attainable, and this, at a decrease value? ” The query actually arises », Considers the EDF security engineer. For instance, by modifying the order wherein the technique of manufacturing are known as up available on the market, which now prioritizes intermittent wind energy over controllable nuclear energy. And even by stopping variations within the energy of a few of EDF’s reactors, he imagines.
” This just isn’t attainable in France “, we object to the ASN. ” The facility of the park exceeds consumption, so we’re pressured to modulate the ability by a number of hundred megawatts, particularly at evening. “says Julien Collet. It have to be stated that throughout the Atlantic, the vitality combine is additionally very completely different from ours: whereas nuclear energy theoretically covers practically 75% of France’s electrical energy demand, this determine doesn’t exceed not the 30% in america. In brief, it can subsequently be a query of taking inspiration, partly, from American strategies, with out nevertheless forgetting these vital disparities.
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