THE EPR OF FLAMANVILLE

Transcription

1 NUCLEAR PHYSIC INSTITUT OF ASCR THE EPR OF FLAMANVILLE EPR report Geoffroy Samour

2 Table des matières Introduction... 3 The EPR compared to his potential rivals... 4 The E.P.R (European Pressurized Reactor),... 6 I- Main objectives Global objectives Standards of safety... 6 II- Overview of the Flamanville 3 EPR Reactor type Core and working conditions Primary and secondary circuit Main auxiliaries systems GUI and control command Accident The construction of the EPR in Flamanville The EPR and the public view EDF and the authority of safety The civil engineering problems Conclusion Page 2

3 Introduction The environmental issues, as greenhouse effect become a vital concern of the public view. The nuclear energy could be an answer of this concern. However, the Chernobyl accident has changed the mentality with the approach of nuclear. Beside the good results in safety field obtained by the western nuclear power plants, the public want to have more secure plants. So, it is necessary to improve the design of the nuclear power plants and adding the knowledge of the core melting in order to prevent better from accidents. It was also important to reduce the impact on the environment in case of accident. This global atmosphere leads the electricity producers to think about the future of nuclear reactors. Indeed, the nuclear is a good solution: economic and environmentally friendly for the electricity producers. That is why all the European electricity producers developed a common needed requirement: the EUR (European Utility Requirements). The EPR (European Pressurized Reactor), developed by the French and German had to respect the EUR and the both authority of safety requirements. So the EPR results from German and French studies about French N 4 reactor and German Konvoi reactor, two reactors from generation II. It involves different European industrial firms (AREVA and SIEMENS), electricity producers (EDF, E.on, EnB, RWE) and nuclear regulatory commission (DSIN and BMV). Nowdays, the EPR is the only third generation reactor, which is under construction in Europe. It is an important step for the nuclear industry. Indeed, for a few years, we have eared about a nuclear revival. The number of nuclear power plant could double. So, it is important to know the advantages of each third generation power plant put forward by the different designer. That is why this study is about the choice of the EPR in Flamanville (FRANCE). First, we will compare the EPR and the other nuclear power plant to understand the choice of the EPR. Then, we will focus on the technology of the EPR. And to conclude, we will undertaken to have an overview of the building site of Flamanville. Page 3

4 The EPR compared to his potential rivals The work shows below is draw one s inspiration from Réflexion sur l économie de l EPR, C.Pierre Zaleski, Sophie Meritet. This study was compared to different other study from USA, UK, Finland and France and the results seems more accurate because: This study compares different other study It has the latest actualization (2004) The study was made by independent people The study is made to compare for different Market: o USA o China o Europe So, in the study, the EPR is compared to: AP 1000 (1175 MWe, Westinghouse) ESBWR (1500 MWe, General Electric) ABWR ( MWe, General Electric) AES 92 ( 1050MWe, Atomstroyexport) The other reactor as PBMR or ACR 700 were not compared because they are not enough accurate data for the markets studied. To compare the different power plant, it is better in a first time to show the overnight cost of construction. Indeed, the financial conditions are independent of the type of the central: Capital cost Tax system Interest However, it could influence by the construction duration but it should be almost the same for the different competitors: EPR ESBWR AP 1000 ABWR AES 92 5 years 5 years 3-4 years 4 years 5 years But, this is just an assessment because today just the EPR is under construction and it is almost 6 years in Flamanville. For the ABWR, it was also building in 4 years in Japan. However for the other plant; we don t have any experience. So for the AP 1000, we can be pessimistic in the abilities to build it in 4 years. To add, they had some difficulties and a lot of delay to build their last power plant in US. Furthermore there Westinghouse hasn t built a plant for many decades. Page 4

5 On one hand, it is difficult to decide between the competitors with the availability of the plant and with the exploitation cost. EPR ESBWR AP 1000 ABWR AES 92 Availability 91% 92% 93% Exploitation costs 12,4 /MWh $11,5 /MWh The discrepancy between the exploitation cost of the EPR and the AP 1000 seems important. However, we could explain it by the different approach. Indeed, for the EPR, EDF uses a reprocess fuel cycle, whereas Westinghouse uses a once through fuel cycle. That is why in fact the exploitation costs are almost the same. Secondly, the availability and the exploitation cost depends more on the company, which manage the plant than the model of plant. (For instance, the availability of Duke Energy is 95% and TVO 90%, while EDF 85%). To finish, for the Russian plant, the costs are unknown. However, it seems that the features are less efficient. So, on the economical approach, it seems that the cost of construction could be the better way to compare the EPR to his competitors: EPR ESBWR AP 1000 ABWR AES In order to compare the cost in Euros and in Dollars, it is necessary to choose a realistic exchange rate, which is not easy. So, an interval from 1 =$1, 15 to 1 =$1,339 has been choose. from 2004 The data from the AP 1000 and the ABWR are older (2002), so an updating has been done in $ The data from the EPR are for sure more accurate than for the other plant because: o The cost are updating during the experience in Finland and in Flamanville o The technology used is close to the N4 and Konvoi: Not a lot of changes in the technology. So it is easier to respect the predictions. The ESBWR and AP 1000 are using an innovating technology passive safety. And this kind of plant has never been built. So it is more difficult to follow the budget because of the non experience about this technology. The data of the AES 92 are older than for the other plant. To add, the technology and the safety is considered as less secure as the western plant. However it is a technology used in different country. The data given for the EPR are for a plant of 1750 MWe, while the other competitors give for an inferior power. So the higher power of the EPR could be an advantage for the market. Don t forget that in this table, the cost of first plant is excluding. Indeed, in some case and more for the AP 1000 and the ESBWR, the cost of the first plant could be very important. So, it is better to compare the cost of first plant separately. Page 5

6 The E.P.R (European Pressurized Reactor), I- Main objectives 1.1 Global objectives The design of the EPR should be able to respect the three main objectives below: a) Compliance with the standards of French and German nuclear regulatory commission b) Producing electricity with competitive cost compared to other energy sources c) Performing the different needs of French and German electricity producers To perform these objectives, it was necessary to find the best technical solutions optimize on the economical field. It enables to have a good competitiveness of the EPR. So the different choices enable: a) The benefit of a serial standardization b) The guaranties of important availability and a low cost of fuel cycle, whereas having an high electrical power 1.2 Standards of safety The standards of safety have been an essential point for the development of the project; particularly for technical choices. According to the French and German nuclear regulatory commissions, the strategy is divided in two parts: a) First time, improving the measures to prevent from accidents b) Second time, limiting radioactive emissions from an eventual accident. It means: - For accident without core melting, the aim is: no population withdraw and no population sheltered from the accident - For accident with core damage, measure of population protection should be brief in terms of duration and space. That is why, the design of the plant use the usual concept of deep defense. So the final solutions were reviewed and completed in using risk reduction measure determinate with probabilistic calculus. The main probabilistic objectives are: - Core melting P<10-5 per reactor and per year. - Core melting due to internal accident (reactor powering) P<10-6 per reactor and per year. - Core melting due to internal accident (reactor shut down) P<10-6 per reactor and per year. - Core melting with earlier water tightness loses of containment P<10-7 per reactor per year. These objectives, extremely inferior as results obtained on the most recent plants functioning across the world forces to consider multiple problem and total loses of redundant system. That is why, it is necessary to take meticulous measures during the design but also during the construction in order to prevent from incident. The protection against external event had also been improved. For example, the EPR resists against the fall of plane. Page 6

7 In the next part of this study, we will show the choices made by EDF for the EPR of Flamanville. To keep in mind the evolution of the EPR, we tried to make the comparisons with the most recent reactors used across the world: the German reactor Konvoi and the French reactor N4. II- Overview of the Flamanville 3 EPR 2.1 reactor type There were a consensus between the authority of safety and the other firms involved in the EPR project in order to consider that the EPR should be an evolution of pressurized water reactor. It means that it directly comes from the last generation of reactor using in France and Germany. This is the only choice to take benefit from a well known technical, while adding the learning of the use since 40 years. In order to build some identical plant on different sites, some general conditions were specified: GENERAL CONDITIONS Common site: - Climate type.. - Seismically level. - External aggression. - Adaptation of needs of the network.. Nuclear steam supply and nuclear island: - Life duration.. - Collective annual dose. - recharging duration. Temperate Acceleration 0,25g, all soil Explosion, fall of commercial plane Charge following, huge flexibility 60 years 0,35/person/dose(Sv/year) 16 days just fuel recharging 11days with maintenance operations So, after reading these features, it is important to highlight the extremely demanding specification of the collective annual dose. This objective could be reach in making choices on the materials and access conditions for maintenance and control. The average availability is fixed at 91% on a duration life of 60 years. It forces to reduce the recharging time. So some disposals for preventive maintenance actions were thinking during the conception in order to limit the recharging time. This purpose was important for the choice of different saving system organized in four redundant trains. 2.2 Core and working conditions The requirement of competitiveness forced to have a high power. It is really adapt to developed country, which have strong interconnected network. The fuel costs are minimized by an important using rate combined with a weakest power density. The reactor has been designed to be flexible for different cycle length (from 12 to 24 months between to recharging shut down). The fuel could be mixed from 50% to 100% of MOX fuel. Page 7

8 In the same time, the pressure and temperature conditions in the primary and secondary circuit are similar to the conditions usually used in the actual reactor. These conditions are compatible with the materials used. It enables to have a reasonable size of components, while providing a sufficient yield. The EPR should be adding in a network, in which the nuclear energy is important. That is why these features should provide a following of electrical supply. It forces to be able to have fast variation of electrical supply. 2.3 primary and secondary circuit The design of the primary circuit, the configuration of loops and the conception of the main components are similar to the plants using in France and Germany. However there are some evolutions. The volumes of water in the primary circuit (vessel+ pressurizer) and in the secondary circuit have been seriously increased. It enables to raise the heat inertia of the nuclear steam supply, in case of perturbation. Steam generators include an axial economizer as on the N4. However, it is possible to the client to choose the materials of the tube. 2.4 Main auxiliaries systems All the usual systems used in PWR are present in the EPR. So, we tried to show you the main evolutions. The supply systems and saving systems (security injection, cooling system, etc ) are organized in 4independant trains, share out in 4savings building. (See the picture) The 4 trains of the safety injection system are supplied by a reservoir placed inside the containment building. It is the opposite of the usual plant, in which the reservoir is situated outside. Thanks to heat exchanger built-in the low pressure injection system, the evacuation of the residual power out of the containment building is done without using an aspiration system (the case in the French plant). However, there is a low pressure injection system; but it is used for serious accident. The reservoir, which is used to supply the security injection, is always assessing to fill the reactor pool in case of fuel charging. The reservoir has been placed inside because: a) Avoid the switch of the injection from the direct mode to recirculation mode, when the reservoir is outside b) Provide the necessary water in order to cool the corium in case of core melting with drill of the vessel Page 8

9 Note: the cooling shut down reactor is done by the low pressure injection system as German reactor. The supply water rescue system of the steam generator has also 4 separate and independent trains. Each one settles in one of the 4 savings building and having its own water reservoir. The trains are linked by cylinder equipped by isolating valve usually bolt. However, they could be open by an operator. The supply rescue pumps are started by electrical motors, which could also started by oil generator. For the start and shut down phases, there is another water supply system to provide the necessary water to the steam generator. This system contributes to the global reliability of the power extraction of the secondary circuit. Indeed, this system reduces the use of the rescue supply system. To add, a diesel generator on each trains of saving is here in case of an external electricity loss. In order to have a better prevention of a total loss, 2 other diesel generator are added. These 2 other generator are directly debiting in low tension board. To summarize, the choice and the organization of the saving system respond to two principles: a) Simplicity: each system is designed for one main function b) Mutual rescue: each main function could be done by a second system (or group of system).if the first failed, nevertheless the intern redundancy. That is why; this conception enables to satisfy the first objective of the safety authority: Improve the prevention of accident. 2.5 GUI and control command The Human factor is one of the most important factors in the quality the exploitation of a nuclear plant. Indeed, human are present in each field of a current use (driving, maintenance, periodical tests, etc ) or in accidental functioning. The solution to avoid problems occurs by the human factor is not the systematic automation. Indeed, the user needs reliable and clear information and action tools. It needs a global design, which offers the possibility to have enough time to make the good decision. The time for the EPR is at least 30 minutes for driving actions launch from the principal command room. This period is more important for intervention, which needs complex operations to 3 days if heavy materials should be used. In the technical point of view, the EPR use the orientation of the landing N4. It is completely computerized, using the most recent technology of microchip. It is the same for the principal control room. It is composed of operator and supervisor position, equipped by screen giving all the information needed. Page 9

10 2.6 Accident To be in compliance with the French and German nuclear authority objectives, the approach of the accident is described below: Impossible situation: Elimination of the situation providing consequences on the environment Eventual situation: containment building should resist and limit the spread to the environment By limit, the safety authority mean: No emergency evacuation up to the first neighborhood No permanent rehousing No limitation in the consumption and selling of the food. The assessment of the consequences is done by using the French law. So, the design of the EPR involves a simplification of emergency plan. That is why, such constraints have some effects on the containment tools conception. So to summarize, the disposition took during the conception are: A system of unload the primary circuit working in case of total loss of the cooling of the secondary circuit. It enables to eliminate a huge accident with a primary circuit. Some passive autocatalytic recombine of hydrogen. In order to eliminate risks of explosions The hypothesis that the corium could drill the vessel, there is a system of recuperation and cooling of this corium. A system of heat exchanger in the containment building with the long term possibility to cooling the water and lower the containment building pressure to atmospherically pressure. Two-layer concrete with total thickness 2.6 meters, designed to withstand impact by airplanes and internal overpressure. It enables to keep all eventual leak (see the graph below); the internal layer is made of water tightness metal, in which the water tightness rate is inferior as 0,5% of the containment building volume. In case of leak, the fluid is evacuated by the ventilation system of the annular area. Page 10

11 The construction of the EPR in Flamanville This part of the report is to show you the problem occurs during the advancement of the project. First of all, it is important to know that this project is not really popular in France. Indeed, the green associations: Greenpeace Sortir du nucleaire Confederation paysanne Are important and made some action against this project. Some actions forced to stop the advancement of the project. Secondly, there are some difficulties which occur because of the difficulty of this project: Quality management Civil engineering Respect of the schedule And finally, there are problems linked with the authority of safety. So, to try to distinguish and made a highlight of this different problem, this part is divided in three paragraphs, corresponding to the three main categories. 1.1 The EPR and the public view The decision to build a nuclear power plant should become difficult to the government. Indeed, there are many examples of projects, which were stop in the past. For instance, the influence used by the green in Spain. In France, the green lobby becomes more and more powerful; but it is not the only association against the EPR. So; in order to respect the law and to have the agreement of the population, a large opinion survey was launched from the 06/15/2006 to the 07/31/2006. The results were in favor of the EPR project in Flamanville. However, the 10/10/2006, six associations: Greenpeace Confederation paysanne Sortir du nucléaire UFC-Que choisir GRAF CRILAN Page 11

12 They wanted to stop the construction of the preliminary civil engineering work because of the lack of studies on the urbanization impact. This was justified by the French coast urbanization law. After a judgment, the request of stopping the construction was canceled (10/26/2006) and the 3/6/2007; the Safety authority authorized the construction of the EPR. This decision launched a serial of actions to protest (strike, blockade, advertising, etc ), which could have some influence on the advancement of the project. So, from the 6/24/2008 to the 6/26/2008, Greenpeace organized a blockade of the project sandpit. It forced the director of the project to stop it. But the project is not only the target of the anti-nuclear associations. Indeed, during the milk crisis, the building site was blockaded. It enabled to the farmer to get a media coverage of the conflict. This is the two main actions against the project. But there is every day some action against it. So, the influence of the media coverage of the site occur some difficulty and trouble for the companies. 1.2 EDF and the authority of safety Building a nuclear power plant is not easy and need a lot of safety processes. That is why, the Authority of safety control everything on the building site: The concrete Each new component However, these controls are not the only. Indeed, the different companies, which work for the EPR have to follow a quality management process. The EDF, which is the main builder in Flamanville and AREVA, which is the main component dealer are the two leaders on the quality management. So some organizations have been created to follow the safety and the quality. It is good to notice that these two firms are qualified as reliable by the HSE (health and safety executive) in UK. Indeed in their report, they wrote that the two firms follow the national and international quality standards and the management system is based on: ISO 9001 ISO IAEA 50-C-Q But, it could have some problem during the construction. So there are two main problems until now. The first occurs during the building of the base of the reactor. Indeed, the weather was not really appropriate to perform the task and some crack appears. So the authority of safety decided to stop the work and wondered rebuild entirely the base. So, the work had to be stopped for 2 month. The second and last problem occurred with AREVA and some component of the steam generator. The authority of safety didn t approve the tools used to test the resistance of these components. So it expected AREVA to make other controls with other machine. The results are that the components are ok. However these two main problems show that there is some lack in the safety and quality management on the building site. Through all the ASN report, this lack is shown. Each time, ASN expected to improve the safety and the quality. This remark is not to report a problem, but to keep in mind that it is always possible to improve the quality management. Page 12

13 To conclude, the relations between the authority safety and EDF are good. We can remark that there are no big problems and each time the company do what is wondering by the authority of safety. 1.3 The civil engineering problems In January 2009, EDF said that the price of the EPR in Flamanville increased by 20%. This is due to the delayed on the building site. For instance they have the difficulties to dig the evacuation tunnel. So, in order to be in time, EDF choose to use new methods more expensive. That is why; the power plant should be finished in 2012 with 20% of over cost. It is difficult to summarize the problems occurs during the construction because EDF and BOUYGUES haven t communicated about. Indeed, if you want more information about the schedule and the different action on the building site, EDF broadcast it on his own website: Conclusion To conclude this part, it is important to highlight the fact that the project is on time. It reveals no important default and shows the capacities of EDF, AREVA and BOUYGUES to build the EPR. The communication between the authority of safety and the different firms work well. About the communication of the different problems occurs, the authority of safety and EDF offer the possibility to download the official documents on their own website. So, the firms have the capabilities and the experience of such project; they are able to follow the schedule with an over cost. The over cost is due to the fact that the EPR of Flamanville is the first of a serial. So, it is normal to have such over cost for a head. Even, we can say that this over cost is not really important compared to the last over cost for the Westinghouse plant in the USA with more than 60% and 10 years delayed. However, the associations against the nuclear are more and more powerful. That is why; it is more difficult to perform the EPR project in good conditions. So, the public views are against this project and organize different actions. These actions affect the view of the EPR. Indeed, they want to misinform the population in order to have a negative impact of the advancement of the project and of the firm. But the reality is different. Page 13