Method for configuring and sizing a nuclear reactor cogeneration plant and system(s) for exploiting heat and electricity produced by the reactor.

Abstract

Method for configuring and sizing a nuclear power cogeneration plant with a nuclear reactor and system(s) for exploiting the heat and electricity produced by the reactor. The invention essentially consists of a reactor, in particular for the thermochemical conversion of carbonaceous material, with a rotating part forming a rotor within a cylindrical vessel forming a stator element. The rotor is in the form of a hollow cylinder, each of the inner and outer walls of which is threaded to form a worm screw, the inner worm screw being in a direction opposite to the outer one, the cylinder being mounted coaxial with the stator vessel and around a central cylindrical wall which forms another stator element. Figure for the abstract: fig.4

Description

Title of the invention: Method for configuring and sizing a nuclear reactor electronuclear cogeneration installation and system(s) for exploiting heat and electricity produced by the reactor. Technical field

[0001] The present invention relates to the field of nuclear reactors, including light water reactors (REL), in particular pressurized water reactors (PWR), but can also be applied to all types of nuclear reactors producing heat, in particular fast neutron reactors (RNR) and molten salt reactors (MSR).

[0002] More particularly, the invention relates to cogeneration installations comprising such nuclear reactors. By "cogeneration" is meant here and within the scope of the invention, the simultaneous and flexible production of electricity and useful heat.

[0003] The invention aims to adapt the entire heat produced to the circuit primary of a nuclear reactor to the needs of a given operating system and, consequently, to limit or even eliminate any environmental impact of the reactor (withdrawals and discharges of liquid water into the environment necessary for the evacuation of fatal heat from the energy conversion cycle).

[0004] Although described with reference to a pressurized water nuclear reactor with a Rankine cycle, the invention applies to any nuclear reactor of the family of so-called second, third, fourth generation (GEN IV) reactors with a thermodynamic energy conversion cycle which may in particular be a Rankine, Brayton, or supercritical CO2 cycle.

[0005] It applies in particular to fast neutron nuclear reactors cooled with liquid metal, in particular liquid sodium known as RNR-Na or SFR (English acronym for “Sodium Fast Reactor”) and which is part of the GEN IV reactor family, with a Brayton cycle. Prior art

[0006] In a context of climate and energy transition, the nuclear industry must meet several challenges for the future. Indeed, to meet the energy and societal challenges of tomorrow, it will be appropriate to design nuclear reactors that allow:

[0007] - to limit the need for so-called “environmental” liquid cold sources (rivers, rivers, sea) and associated discharges into the environment;

[0008] - to maximize the energy efficiency of nuclear reactors by not considering exclusively their electrogenic role but by considering an integrated approach to the use of electricity and heat in the service of the energy transition,

[0009] - to be more flexible and therefore more complementary to other so-called renewable energies renewable energy sources (ENR), to meet fluctuating electricity demand and the intermittency of ENR;

[0010] - to decarbonize processes by providing heat to consumer industries matrices (desalination, heat networks, hydrogen, etc.) while increasing energy efficiency;

[0011] - to capture atmospheric CO2 to limit the effects of global warming climate and contribute to closing the carbon cycle as a carbon source for industrial processes;

[0012] and this, without degrading the profitability of the installation, either by economically benefiting from the new services provided, or by significantly increasing the quantity of electricity produced during the day.

[0013] A pressurized water nuclear reactor (PWR) typically comprises three cycles (fluid circuits) whose general principle of normal operation is explained below with reference to [Fig.l]. The temperatures and efficiency are indicated for illustrative purposes.

[0014] The primary circuit 1 is a closed-loop fluid circuit mainly comprising the core of the reactor 2, at least one steam generator (SSG), as an exchanger called primary exchanger 3 and a hydraulic pump 4 for circulating the heat transfer fluid which is water maintained in the liquid state in the operating temperature range of the reactor, typically around 320°C-330°C in normal operation. Other equipment, such as a pressurizer and all the devices making it possible to ensure operation under the required safety conditions, are not described here.

[0015] Thus, the high-pressure water in the primary circuit extracts the energy supplied, in the form of heat, by the fission of the uranium nuclei, in the core of reactor 1.

[0016] Then, this water under high pressure and high temperature, typically 155 bars and 320°C-330°C, enters the intermediate exchanger 3 and transmits its energy to a secondary circuit 5, also using pressurized water as a heat transfer fluid in a closed loop.

[0017] This secondary circuit 5 comprises the intermediate exchanger 3, a turbine 6 comprising a high pressure body 60 and a low pressure body 61, a condenser 7 and a hydraulic pump 8 for circulating the water in the form of steam as a heat transfer fluid.

[0018] Thus, in this secondary circuit 5, the water in the form of steam, at high pressure, ty peak at approximately 70 bars, is expanded in the high pressure body of the turbine, then superheated before continuing its expansion in the low pressure bodies 61. The turbine drives an alternator 9 which produces electricity.

[0019] The water in the secondary circuit is then condensed via the condenser 7 in a third cycle, the cooling cycle 10, as a so-called "cold" source. For nuclear power plants on the banks of rivers or streams, this cycle 10 mainly comprises humid air cooling towers 11, which are towers in which a current of air is created, naturally by natural convection or forcedly, entering at the bottom and exiting at the top.

[0020] In passing, this air current takes the heat contained in the water of the cooling circuit by increasing its relative humidity until saturation and disperses it in the atmosphere in the form of a cloud of water vapor.

[0021] The operation is reproduced continuously in which the water is distributed into fine droplets, which allows on the one hand a good exchange between the water and the air and therefore brings the water to a temperature close to that of the ambient air, and on the other hand saturates with water vapor the air flow circulating from bottom to top in the tower. Part of the water flow evaporates in the tower 11, the rest falls as rain, having given up its calories for the evaporation of the rest of the flow, in the basin located below the tower where it is pumped and returns to cool the condenser 7.

[0022] The evaporated water is replaced by tertiary water called "environmental" pumped upstream from a river or stream. In order to deconcentrate the waters of the basin in salts and minerals, due to evaporation, a fraction of the flows is discharged downstream of the site into the river or stream. The environmental impact of these withdrawals and discharges is assessed as part of the preliminary studies aimed at authorizing the creation and operation of the site, but global warming leads to periods during which the flow and temperature conditions of the river or stream cause the operator of the nuclear installation to reduce their power level, or even to have to shut down the reactor.

[0023] In the classic REP sector, existing or planned reactors can be classified by major families of uses according to the role they can play in terms of low-carbon energy source:

[0024] - so-called electrogenic reactors which are dedicated solely to production of electricity;

[0025] - so-called calogenic reactors which are dedicated solely to the production of heat;

[0026] - so-called cogeneration reactors, dedicated to both the production of electricity and heat, simultaneously or not.

[0027] The electrogenic REP reactors have been designed to produce exclusively, and therefore in an optimized manner, electricity: the most thermodynamic conversion cycle The most widespread is that of Rankine.

[0028] The following graph T / S (Temperature / Entropy) of a Rankine thermodynamic cycle as illustrated in [Fig.2] highlights the operating configuration of such a cycle for a reactor 1 illustrated in [Fig.l], for exclusively electrogenic purposes.

[0029] The conversion cycle is designed so that the work sent to turbine 6 (Wturbine between points 3 and 4 of the graph in [Fig.2]) is maximum.

[0030] To do this, the system is designed so that the gap between the two isotherms (lines 2'-3 and 1-4 parallel to the abscissa axis in [Fig.2]) is maximum.

[0031] A nuclear installation aiming at optimizing only electrical production is therefore designed to have the hottest possible hot source (high isotherm) and the coldest possible cold source (low isotherm). Maximizing electrical production results in an overall thermodynamic efficiency of approximately 33% (variable depending in particular on the meteorological conditions at the installation site).

[0032] On the graph of [Fig.2], the quantities represented are characteristic of a Rankine cycle on a PWR reactor with a hot source of the order of 280°C (the core outlet temperature is of the order of 320°C) and a cold source of the order of 30°C.

[0033] The "lost" heat or fatal heat (Qlost on the graph of [Fig.2], at the low isotherm) represents the quantity of energy that must be dissipated by means of an external cold source.

[0034] In [Fig.l], this cold source is cycle 10 at the terminals of condenser 7.

[0035] The Rankine cycle can then be characterized by an efficiency, expressed in %, which reflects the share of electrical power actually produced in relation to the thermal power injected.

[0036] As mentioned above, the production efficiency is primarily linked to the temperature of the hot source and the temperature of the cold source at the cycle terminals.

[0037] This efficiency is defined by equation 1, as follows:

[0038] [Equation 1]

[0039] „ _ electricity produced K-cvcle ~p~ ~~ 1 reacteii-r

[0040] By the principle of conservation of energy, we get equation 2:

[0041] [Thermal equation reactor P fatal thermal P electrical produced

[0042] in which: - Thermal reactor ■ thermal power of the core expressed in units [MWth], - Electric power produced ■ electric power produced expressed in unit [MWe], - Rcycie ■ the thermodynamic efficiency of the cycle expressed in %, - Pthermiquefataie ■ fatal thermal power expressed in unit [MWth].

[0043] While the fission reactions within the nuclear fuel produce much more heat, the temperature of the water leaving the core is around 300°C and constitutes the hot source of the thermodynamic cycle.

[0044] This temperature level is the result of a technical and economic compromise linked to the control of the pressurization of the water in the primary circuit to maintain it in liquid water. In the case of a PWR, as indicated previously, the pressure within the primary circuit 1 is maintained around 155 bars to ensure that the water remains liquid at all points in the circuit. Indeed, the installation is designed, including the associated safety demonstration, to remain exclusively in liquid water. To this end, to ensure pressure maintenance and guarantee the absence of steam, the primary circuit incorporates a pressurizer.

[0045] Thus, as illustrated in [Fig.3], from publication [1], the primary circuit 2 is made up of the following main components:

[0046] - a reactor vessel 20,

[0047] - primary loops 21, preferably four loops 21, each comprising a primary pump 22 and a steam generator 23,

[0048] - a single pressurizer 24.

[0049] Furthermore, in this [Fig.3], the control rod mechanisms of the reactor core and control clusters 25 can be seen.

[0050] Depending on the power of the reactor, the number of loops can be three for a 900 MWe reactor ([Fig.3]) or four for a 1300 MWe reactor and above.

[0051] The pressure versus temperature graph in [Fig.4] shows the water vaporization curve between 0°C and the melting point at 374°C. As can be seen, pressurizing the primary circuit to approximately 150 bars, in this case 155 bars for a conventional PWR, makes it possible to maintain temperature values ​​of around 300°C in the liquid water range.

[0052] This pressurization constraint leads to: - sizing of the entire primary circuit which must guarantee mechanical resistance at such pressure levels, in particular significant structural thicknesses with related safety provisions, - the implementation of safety devices and provisions to guarantee the risks and consequences associated with a failure in the primary circuit.

[0053] For example, safety analyses of a PWR reactor lead to taking into account the scenario of rupture of a fluid line of the primary circuit, which generates a significant energy release due to the expansion by vaporization of the pressurized water of the primary circuit when it is released into the atmosphere.

[0054] This scenario is the origin of significant mechanical loading requirements on the reactor building which constitutes the third containment barrier in the case of a PWR reactor.

[0055] In other words, maximizing the electrical production of an existing nuclear installation leads to oversizing within it and therefore additional investment costs.

[0056] To illustrate oversizing, reference may be made to the design rules retained for a primary circuit and more particularly those on the thickness of the primary tank 20 and the pipes forming the fluid lines of the loops 21 of the primary circuit.

[0057] The minimum thickness of a component of the primary circuit is defined by the design collection applicable in the French reference system, designated under RCC-MRx RB3332.1.

[0058] This thickness is calculated according to equation 3:

[0059] [Equation 3]

[0060] . = ^mini 2x<7axZ+P

[0061] with: - emini: the minimum thickness [m] - P: the internal pressure of the component [MPa] - Outside ■ the outside diameter of the component (tank or pipe) [m] - : the admissible stress [MPa] - Z: the welding coefficient [unitless].

[0062] Thus for a primary circuit component, the admissible stress values ​​retained according to materials are summarized in table 1.

[0063] [Tables 1] Constituent material of the component ^(MPa) T° range steel 16MND5 184 Between 20 and 350°C steel 316L(N) 112 325°C

[0064] For the value of the welding coefficient, the RCC-MRx design collection recommends a value of 1 because the welds have a greater resistance than the constituent material (steel), and assuming that the control coefficients are equal to 1.

[0065] In application of the aforementioned equation 3, the minimum thicknesses for the components of the primary circuit are given in the following table 2. The actual thicknesses are greater in particular for safety reasons leading to taking dimensioning margins.

[0066] [Tables2] Primary circuit component Outer diameter Constituent material ^mini Reactor vessel 20 5 steel 16MND5 20 cm Loop pipe 21 0.75 steel 316L(N) 5 cm

[0067] Furthermore, on the side of the cold source 10, the temperature level depends on the value of the temperature of the cooling water at the terminals of the condenser 7. Here too, for reasons of maximizing electrical production, the design focuses on cold sources, with the lowest possible intrinsic temperatures.

[0068] There are three main cooling configurations for REP nuclear installations:

[0069] - so-called direct cooling by transmission of sensible heat where the cold source is made up of either river water or sea water,

[0070] - so-called indirect cooling by transmission of latent heat. In this case, the The cold source used is humid air, by means of cooling towers, such as towers 11 illustrated in [Fig. 1]. A water make-up is required to maintain the water inventory, due to evaporation, and to ensure purges, due to the increasing concentration of residual salt and minerals in the non-evaporated liquid water inventory and due to the evaporated fraction.

[0071] Depending on the desired location area for the nuclear installation, it is the geography and particularly the hydrographic conditions which will determine the temperature conditions of the cold source.

[0072] In France, taking into account the meteorological conditions, as shown in [Fig.l], for example, the thermodynamic efficiency of a PWR type reactor is of the order of 33 to 34%, the water temperature is of the order of 20°C at the inlet of the condenser 7 and 35°C at its outlet.

[0073] In other words, maximizing the electrical production of an existing nuclear installation leads to installation constraints and an environmental impact linked to the withdrawal and discharge of cooling water. Typically, the desired cold source temperature is between 15°C and 25°C depending on the nature of the cold source (river water, sea water) and the meteorological and hydrographic conditions of the installation site.

[0074] As detailed in [2], the principle of cogeneration from a nuclear reactor consists of modifying the design of the energy conversion cycle so that the heat is released at the cold source at a temperature which allows a valo- rization.

[0075] A known configuration of a nuclear cogeneration installation is illustrated in [Fig.5]: it comprises, in addition to the usual components of an installation with a usual PWR reactor, a heat exploitation system 20 connected in a closed loop to the condenser of the secondary circuit 7 of the reactor, with a cooling system 22 as a bypass.

[0076] By way of example, the system 22 may be a system for capturing atmospheric or concentrated CO2 or a seawater desalination system or a system for directly recovering the heat produced, with cooling as a by-pass such as a dry air cooling tower 20. Any other system that requires electrical energy and heat may be envisaged.

[0077] With the alternator 9 connected to an electrical network 21, the installation of [Fig.5] can therefore achieve cogeneration of heat and electricity.

[0078] The energy requirements of a nuclear cogeneration facility that produces heat and electricity are characterized by the following three physical quantities:

[0079] - Pthermiquecogénération: thermal power required by the cogeneration installation, expressed in unit [power] / [quantity produced], for example in kWth / kg for a CO2 capture system or in kWth / m3 of desalinated water for a desalination system,

[0080]

[0081]

[0082]

[0083]

[0084]

[0085] - Cogeneration system: electrical power required by the cogeneration installation, expressed in units [power] / [quantity produced], for example in kWe / kg for a CO2 capture system or in kWe / m3 of desalinated water for a desalination system, - Cogeneration temperature: temperature required by the cogeneration installation, expressed in °C or °K. From these data, the cogeneration ratio can be evaluated according to equation 4: [Equation 4] P, Tj * electric co^enercitiw t^coegeneration ~p~, ~ ” •' 1 thermal cogeneration Table 3 below summarizes the energy requirements for a cogeneration installation considered as orders of magnitude from the open literature, in which the system for exploiting the heat produced is respectively a seawater desalination system and an atmospheric CO2 capture system by direct capture in the air, known under the Anglo-Saxon terminology "Direct Air Capture" (DAC):

[0086] [Tables3] Heat exploitation system Energy requirements Electricity Heat Quantity Unit Quantity Unit Seawater desalination 2 kWe / m3 40 kWth / m3 90 Atmospheric CO2 capture (DAC) 0.4 Mwe / tonne co2 1.6 Mth / tonne CO2 90

[0087] For each of these two systems, the needs are therefore distributed over both electricity and heat. For example, electricity is needed to operate pumps (build up pressure, create a vacuum) or fans, via electric motors. Heat is required to respectively vaporize seawater or regenerate substrates or solvents that have captured atmospheric CO2.

[0088] Whatever the configurations of the nuclear cogeneration installations which have been envisaged to date, and the energy needs required by the systems for exploiting the heat generated by the nuclear reactor(s) of the installation, the latter as well as their thermodynamic conversion cycles remain fundamentally designed from the paradigm of exclusive production of electricity, as presented above.

[0089] And from this paradigm arises, in addition to oversizing within an installation and therefore additional investment costs, the need to have a cold source with the corollary of geographical positioning constraints for this cooling function and an environmental impact due to the withdrawals and discharges of cooling water.

[0090] There is therefore a need to improve the designs of nuclear cogeneration installations, in order to make the best use of both the electricity produced and all of the heat produced in the primary circuit of the reactor(s) to avoid the need for a cold source.

[0091] The aim of the invention is to at least partially meet this need. Statement of the invention

[0092] To do this, the invention relates, in one of its aspects, to a method for configuring and dimensioning an electronuclear cogeneration installation comprising:

[0093] - at least one nuclear reactor, comprising:

[0094] a first fluidic circuit, called primary circuit, comprising at least one tank of reactor and an intermediate heat exchanger connected in a closed loop to the reactor vessel;

[0095] a second fluid circuit, called secondary circuit, adapted to exploit a thermodynamic energy conversion cycle, comprising at least one turbine connected to the intermediate heat exchanger, a condenser connected to the turbine and to the intermediate heat exchanger, to cool the steam coming from the turbine and transform it back into water and return it to the intermediate heat exchanger;

[0096] an alternator mechanically coupled to the turbine,

[0097] - at least one fluidically connected heat and electricity operating system in closed loop to the condenser of the secondary circuit of the reactor and electrically connected to the alternator;

[0098] the method comprising the following steps:

[0099] a / characterization of the energy needs of the heat and electricity operating system, including the thermal and electrical powers, the inlet temperature (T2) required by the system, and the temperature difference at the terminals of the operating system(s),

[0100] b / calculation of the cogeneration ratio of heat and electricity by the installation, based on the characterization of the needs according to step a / ,

[0101] c / calculation of the efficiency of the thermodynamic cycle of the secondary circuit, from the calculation of the cogeneration ratio according to step b / ,

[0102] d / determination of the thermodynamic cycle adapted to obtain the efficiency calculated according to step c / , with the temperature level required for the heat supply of the operating system(s) at the terminals of the condenser,

[0103] e / from the outlet temperature (Tl) of the system, from the thermodynamic cycle determined according to step d / and from its efficiency calculated according to step c / , configuration and sizing of the secondary circuit and determination of the temperature of the fluid at the inlet of the intermediate exchanger,

[0104] f / from the temperature of the fluid at the inlet of the intermediate exchanger determined according to step d, configuration and sizing of the primary circuit.

[0105] By “configuration and dimensioning” is meant here and within the framework of the invention, the determination of all the components, the arrangement between them and the determination of their physical characteristics, in particular their dimensions.

[0106] According to an advantageous embodiment variant, step b / is carried out by considering that the thermal and electrical powers required by the system are respectively equal to the thermal power at the terminals of the condenser, supplied by the secondary circuit and the electrical power delivered by the alternator.

[0107] According to a first application, the nuclear reactor is pressurized water (PWR) and the thermodynamic cycle of the secondary circuit is a Rankine cycle.

[0108] According to a first application, the nuclear reactor is a fast neutron reactor (RNR) and the thermodynamic cycle of the secondary circuit is a Brayton cycle.

[0109] Advantageously, step f / comprises the dimensioning of the reactor vessel and the fluid line of the primary circuit.

[0110] Advantageously, the heat and electricity exploitation system is a system for capturing atmospheric carbon dioxide CO2 and / or desalination of sea water according to a so-called multiple-effect process (MED) or a so-called staged expansion distillation process (MSF).

[0111] Advantageously, the operating system can implement any other process operating in cogeneration that one would seek to couple with a nuclear reactor and whose required heat temperature level would be compatible with a supply at the terminals of the condenser of the thermodynamic cycle.

[0112] The invention also relates to a cogeneration installation configured and sized according to the method as described above, which is free from a cold source of environmental water.

[0113] The invention essentially consists of a method which makes it possible to configure and size a nuclear cogeneration installation, no longer according to the state-of-the-art design paradigm which was focused on optimizing the gross electrical output of a nuclear reactor, but by considering the maximum energy efficiency of the entire installation, namely the nuclear reactor and its cycles as well as the system for exploiting the heat and electricity produced by the reactor.

[0114] In other words, the invention aims to design nuclear reactors to optimize the energy coupling, both of the heat and the electricity produced, with a system which is intended to exploit them, preferably to the point of eliminating the need for a cold source of environmental water while having total energy efficiency.

[0115] This adaptation makes it possible to relax the design criteria imposed on an electric nuclear reactor connected to an electrical network, as according to the state of the art and which arise on the one hand from the constraints linked to flexibility with regard to the electrical control of the network and on the other hand from the optimization of the desired electric efficiency, which consists of having the highest possible temperature at the outlet of the reactor core.

[0116] This alleviates the constraints of sizing structures and accelerated aging.

[0117] Once the energy requirements of the operating and heat system have been determined, and therefore the thermal and electrical powers as well as the temperature required by the system have been defined, the configuration and sizing according to the invention involve an adaptation of the thermodynamic conversion cycle of the nuclear reactor.

[0118] In particular, for a Rankine cycle, this amounts to modifying the entropy-temperature diagram.

[0119] Thus, as shown in [Fig.7], this modification consists of: - increase the low isotherm (bottom dotted line in [Fig.7]) to the temperature level T2 at the terminals of the Rankine cycle condenser, which is required for the heat supply of the operating system, - lower the upper isotherm (top dotted line in [Fig.7]) so as to obtain the electrical efficiency of the Rankine cycle required for the power supply of the operating system.

[0120] This rapprochement of the isotherms will lead to a reduction in the thermodynamic efficiency of the Rankine cycle, and therefore simplify the latter, which until now has been optimized to maximize electricity production in power-generating PWR reactors according to the state of the art. Furthermore, it will lead to a hot temperature at the outlet of the reactor core and therefore make it possible to reduce the pressure of the primary circuit. This is illustrated by the arrow in [Fig.8].

[0121] Ultimately, a nuclear cogeneration installation according to the invention has many major advantages, among which we can cite:

[0122] - optimized energy efficiency because all the nuclear energy produced by the core is used. Thus, all of the heat produced by the core and the electricity converted by the thermodynamic cycle is exploited by the coupled system;

[0123] - a simplification of the components of the part of the installation carrying out the conversion of heat into electricity, including the possible elimination of certain turbine bodies;

[0124] - a simplification of the nuclear reactor, for example the reduction of thicknesses pressurized structures resulting in reduced manufacturing costs;

[0125] - an improvement in safety by reducing the pressure in the primary circuit of the reactor;

[0126] - an increase in the lifetime of the structures of a reactor which does not load tracking, and operates at a lower temperature;

[0127] - the possible elimination of a cold source in environmental water (sea, river or river) to evacuate the fatal heat because all the nuclear heat is used by the operating system which is coupled to the condenser;

[0128] - due to the elimination of a cold source, the absence of cooling water discharges development and therefore a limited impact on the environment and on global warming. For example, we can consider operating the installation during periods of heatwave or low river water levels;

[0129] - as a corollary of the absence of the need to have a significant cold source, a complete freedom in the choice of geographical location of the installation, which gives interesting perspectives for CO2 capture systems or seawater desalination for example. In particular, one can consider an installation in countries with a hot and dry climate, not benefiting from a river, stream or sea in their geography and / or on sites which are potentially landlocked, where land is less expensive;

[0130] - a significant simplification of the design of the nuclear island and the cycle of thermodynamic conversion of the installation and consequently a reduction in the associated CAPEX;

[0131] - a simplification of reactor safety demonstrations, mainly by the reduction of pressure in the primary circuit of the reactor;

[0132] - a significant lengthening of operating cycle times compared to those of a conventional PWR reactor because the nuclear fuel is less in demand, which increases the availability rate of the installation (no shutdown to replace the fuel).

[0133] The inventors overcame a technical prejudice which was based on considering that the maximization of electrical production to make a nuclear power plant profitable always required designing the latter with the lowest possible temperature level of the cold source and the highest possible temperature level of the hot source.

[0134] The heat and electricity exploitation systems which can be advantageously considered are:

[0135] - seawater desalination systems requiring thermal energy, for example example according to a so-called multiple-effect process ("Multi-Effect Distillation" in English with the acronym MED) or so-called multi-stage flash distillation process ("Multi-Stage Flash distillation" in English with the acronym MSF),

[0136] - the capture of atmospheric CO2 to contribute in particular to implementing the closing the carbon cycle and initiating a circular carbon economy.

[0137] Ultimately, this mode with this thermal storage and heat distribution loop brings a good number of additional advantages among which we can cite: - the energy conversion system of the cogeneration installation can operate completely independently of the heat exploitation system(s), both on the hot source side (reactor) and on the cold source side (condenser terminals), thus enabling both total flexibility in the service of the electricity network and a maximum and optimized availability rate, with the consequences that this has on the economy of the nuclear reactor of the installation; - the possibility of positioning in parallel different systems for exploiting the heat from the nuclear reactor not consumed by the energy conversion system into electricity and therefore, of increasing the capacity to address energy markets and services with characteristics and needs profiles different from those of electricity; - the physical decoupling between the nuclear reactor conversion cycle and the operating system(s) by thermal storage tanks which act as buffers, which makes it possible to considerably limit the risk of propagation of an accident / incident induced by one of the sites on which the nuclear reactor is located on the one where one or other of the operating systems is located, and vice versa; - the fact that at a constant daily operating rate and not linked to the operation of the electricity production service, oversizing of the heat exploitation system(s) is no longer necessary. This oversizing is due to the need to evacuate all the thermal power from the reactor core not transformed into electricity over a shorter period of time (the operating time of the energy conversion system into electricity).

[0138] Other advantages and characteristics of the invention will become more apparent upon reading the detailed description of examples of implementation of the invention given by way of illustration and not limitation with reference to the following figures. Brief description of the drawings

[0139] [Fig-1] [Fig.l] schematically illustrates a configuration of a water reactor pressurized (REP) operating solely as a state-of-the-art power reactor.

[0140] [Fig.2] [Fig.2] is the entropy diagram of the Rankine cycle implemented in the secondary circuit of the generator reactor configuration according to [Fig.l].

[0141] [Fig.3] [Fig.3] is a schematic view of the components with the circuit loops primary of a PWR reactor according to the state of the art.

[0142] [Fig.4] [Fig.4] is the diagram of pressure as a function of temperature of a state-of-the-art PWR reactor.

[0143] [Fig.5] [Fig.5] is a schematic view of a cogeneration installation comprising a pressurized water reactor (PWR) with an alternator connected to an electrical network and a heat exploitation system, such as an atmospheric CO2 capture system and an air-cooling device operating with dry air as a bypass of the heat exploitation system, according to the state of the art.

[0144] [Fig.6] [Fig.6] is a schematic view of a cogeneration installation comprising a pressurized water reactor (PWR) and a system for operating both heat and electricity, which is configured and sized according to the method of the invention.

[0145] [Fig.7] [Fig.7] is the entropy diagram of the Rankine cycle of an installation cogeneration according to [Fig.6], determined with the method according to the invention.

[0146] [Fig.8] [Fig.8] is the diagram of pressure as a function of temperature of the primary circuit illustrating the consequence of the evolution of the Rankine cycle in a cogeneration installation configured and sized with the method according to the invention.

[0147] [Fig.9] [Fig.9] illustrates in graphic form the thermodynamic efficiency of the Rankine cycle determined as a function of the cogeneration ratio required by the heat and electricity exploitation system, according to the invention.

[0148] [Fig. 10] [Fig. 10] is the diagram of the pressure as a function of the temperature of the primary circuit in a cogeneration installation configured and dimensioned with the method according to the invention, for a heat and electricity exploitation system consisting either of a seawater desalination system with solid capture, or an atmospheric CO2 capture system (DAC). Detailed description

[0149] Figures 1 to 8 relating to the state of the art and to a cogeneration installation according to the invention have already been detailed in the preamble, they will therefore not be commented on below.

[0150] The inventors have carried out the configuration and dimensioning of the installation according to [Fig.6],

[0151] Among the various possible technologies for the heat 20 and electricity 23 exploitation system, the inventors have retained those whose energy needs are the most relevant for a cogeneration coupling in the configuration of the installation according to [Fig.6], namely a CO2 capture system by solid adsorption (DAC) and a seawater desalination system implementing the multi-effect distillation process (Multi-Effect distillation MED).

[0152] The energy requirements of these systems were characterized from published data, respectively in [3] and [4].

[0153] Table 4 below summarizes the energy requirements of these systems, in average values.

[0154] [Tables4] Heat and power system Energy requirements Electricity Heat Quantity Unit Quantity Unit T2 (°C) Seawater desalination (MED) 2 kWe / m3 50 kWth / m3 90 Atmospheric CO2 capture (DAC) 0.4 Mwe / tonne co2 1.6 Mth / tonne co2 90

[0155] For each of these two systems, the needs are therefore distributed over both electricity and heat.

[0156] The required temperature T2 is therefore known, equal to 90°C. It is therefore sufficient to give the temperature T2 as the boundary condition of the Rankine thermodynamic cycle at the terminals of the condenser 7.

[0157] We now determine the value of the electrogenic efficiency of the Rankine cycle, the most accurate, that is to say the one which starts from the hypothesis that all the heat and electricity produced are exploited by the system 20, 23, without a cold source of environmental water.

[0158] In other words, we consider that:

[0159] - all the fatal heat at the exit of the Rankine cycle is exploited to respond to the power and temperature requirements of the heat required by the operating system, in order to ensure maximum energy efficiency,

[0160] - the return temperature Tl of the system 20 is compatible with the cooling requirement development of the Rankine cycle, in order to free itself from a cold source of environmental water,

[0161] - the amount of electricity produced by the Rankine thermodynamic cycle is equal to the amount of electricity required by the system 23.

[0162] These hypotheses are translated by the following equations 5 and 6.

[0163] [Equation 5]

[0164] Pthermic cogencratirm P fatal thermal

[0165] [Equation 6]

[0166] Electricity produced by cogeneration

[0167] By injecting into equation 4, as mentioned in the preamble, equations 5 and 6, we obtain equation 7:

[0168] [Equation 7]

[0169]

[0170]

[0171]

[0172]

[0173]

[0174]

[0175]

[0176]

[0177]

[0178]

[0179]

[0180]

[0181]

[0182]

[0183] rj __ Peleciriqué produced ^■Cogeneration p ' 7 ” 0 1 thermal / uuue. With equation 2, we obtain equation 8: [Equation 8] -electricity produced. ^■Cogeneration ~p~. ï " .pï , ° 1 thermal reactor 1 electrical prodw.te By reversing equation 8 we obtain equation 9: [Equation 9] , P . ] __ 1 thermal reactor । RcûgéflémliûH Electricity produced Hence equation 10: [Equation 10] jrj __ Co-management Kcvcle "p “ : | the coqenerattntc A From equation 10, it is therefore possible to evaluate the efficiency of the Rankine conversion cycle from the cogeneration ratio of the system 20, 23 which is thermally and electrically coupled. [Fig.9] thus illustrates the curve of the thermodynamic efficiency of the Rankine cycle as a function of the cogeneration ratio. From this graph it is possible to give a limit in the cogeneration ratio for the chosen system. Table 5 below gives the values ​​of the cogeneration ratio and the efficiency of the Rankine thermodynamic cycle associated with each of the two systems considered. [Tables 5] Heat and power system Cogeneration ratio Rankine cycle thermodynamic efficiency Seawater desalination (SWD) 0.04 5% Atmospheric CO2 capture (ACC) 0.25 20%

[0184] Once the thermodynamic efficiency has been determined, and knowing the cold temperature Tl of the Rankine cycle imposed by the system 20, thermodynamic cycle modeling tools make it possible to evaluate the temperature level required at the steam generator inlet and therefore, to deduce the pressurization level of the primary circuit.

[0185] The inventors carried out the dimensioning of all the components of the cycle from an internal software, used under the name CYCLOP, qualified by the applicant for dimensioning in permanent mode of conversion cycle thermodynamics.

[0186] The use of this software is for example described in [5] or [6]. The dimensioning can also be carried out using other commercial software, in particular that under the name THERMOFLEX®.

[0187] The inventors thus determined the configuration of the cycle and the temperature level required at the steam generator inlet on the hot branch of the primary circuit.

[0188] For an atmospheric CO2 capture (DAC) system, one configuration highlights the simplification of the secondary circuit implementing the Rankine cycle, including simplifications on the usual heaters and dryers.

[0189] The sizing results of the primary circuit associated with each of the two systems considered are presented in Table 6 below:

[0190] [Tableauxô] Heat and power operating system Temperature T3 (°C) Pressure (bar) Seawater desalination (MED) 148 7 Atmospheric CO2 capture (DAC) 249 41

[0191] These data are reported on the diagram in [Fig.10].

[0192] These evaluations highlight that the configuration and dimensioning method according to the invention makes it possible to very considerably reduce the pressure of the primary circuit and therefore makes it possible to very greatly simplify the design of the PWR reactor according to the state of the art as explained in the preamble and illustrated in [Fig.l].

[0193] As an example, it is proposed to highlight the consequence of the drop in pressure of the primary circuit on the thicknesses of the structures on the primary circuit, more particularly on those of the reactor vessel and of a primary circuit pipe.

[0194] In application of the sizing rules of the RCC MRX collection, the resulting minimum thicknesses are evaluated and presented in table 7 below, in comparison with those of a REP reactor according to the state of the art.

[0195] [Tables?] Primary circuit Nuclear reactor REP according to the state of the art Heat and electricity exploitation system according to the invention Seawater desalination (MED) Atmospheric CO2 capture (DAC) Pressure (bar) 155 5 41 Reactor vessel Minimum diameter (m) 5 5 5 Minimum thickness (cm) 21 1 5 Fluid line Minimum diameter (m) 0.75 0.75 0.75 Minimum thickness (cm) 5 0.2 1

[0196] This table 7 therefore highlights the significant reduction in thickness required to ensure the mechanical strength of the structures in the primary circuit of a cogeneration installation reactor for a desalination system or a CO2 capture system coupled as a heat and electricity operating system.

[0197] The invention is not limited to the examples which have just been described; it is possible in particular to combine characteristics of the examples illustrated within non-illustrated variants.

[0198] Other variants and embodiments may be envisaged without departing from the scope of the invention.

[0199] The two couplings (capture of atmospheric CO2 and desalination of seawater) are given as an example, and the present invention can be applied to any other cogeneration system requiring a heat input compatible with the technology of the REP reactor with Rankine cycle.

[0200] Generally, one or more heat and electricity operating systems can be implemented connected in a closed loop and in parallel to the condenser of the secondary circuit of the reactor, and connected to the alternator, without any cold water source.

[0201] The nuclear cogeneration installation which has just been described in relation to a pressurized water nuclear reactor with a Rankine cycle can be implemented with all nuclear reactors with an indirect thermodynamic cycle, for which the heat production cycle is physically separated from the energy conversion cycle. List of cited references

[0202] [1]: “Heat recovery from nuclear power plants”, H. Safa, International Journal of Electrical Power & Energy Systems, Volume 42, Issue 1, November 2012, Pages 553-559.

[0203] [2]: "Improving energy efficiency by using cogeneration in the electricity production' Jean-Marie Loiseaux, Henri Safa, Bernard Tamain, Save the Climate Network.

[0204] [3]: IEA report of April 2022: https: / / iea.blob.core.windows.net / assets / 78633715-15c0-44el-81df-41123c556d57 / Dir ectAirCapture_Akeytechnologyfometzero.pdf.

[0205] [4]: https: / / www.irena.org / - / media / Files / IRENA / Agency / Publication / 2012 / IRENA-ETSAP -Tech-Brief-I12-Water-Desalination.pdf

[0206] [5]: HD Nguyen, N. Alpy, D. Haubensack. “Insight on electrical and thermal powers mix with a Gen2 PWR: Rankine cycle performances under low to high temperature grade cogeneration.” Energy, Elsevier, 2020, 202, pp. 117518. ff 10.1016 / j.energy.2020.117518ff. ffcea-0256923If.

[0207] [6]: D. Haubensack et al., “The COPERNIC / CYCLOP computer tool: pre-conceptual design of génération 4 nuclear Systems, HTR-2004”, 2nd International Topic Conférence for the HTGR, September 22-24, 2004, Beijing, China, 2004.

Claims

1. Claims Method for configuring and sizing a nuclear cogeneration installation comprising: - at least one nuclear reactor, comprising: a first fluid circuit, called primary circuit (1), comprising at least one reactor vessel (2) and an intermediate heat exchanger (3) connected in a closed loop to the reactor vessel; a second fluid circuit, called secondary circuit, adapted to exploit a thermodynamic energy conversion cycle, (5) comprising at least one turbine (6, 60) connected to the intermediate heat exchanger, a condenser (7) connected to the turbine and to the intermediate heat exchanger, to cool the steam coming from the turbine and transform it back into water and return it to the intermediate heat exchanger; an alternator (9) mechanically coupled to the turbine, - at least one heat (20) and electricity (23) operating system, fluidically connected in a closed loop to the condenser of the secondary circuit of the reactor and electrically connected to the alternator; the method comprising the following steps: a / characterization of the energy needs of the heat and electricity operating system, including the thermal and electrical power, the inlet temperature (T2) required by the system and the temperature difference at the terminals of the operating system(s), b / calculation of the heat and electricity cogeneration ratio by the installation, based on the characterization of the needs according to step a / , c / calculation of the efficiency of the thermodynamic cycle of the secondary circuit, from the calculation of the cogeneration ratio according to step b / , d / determination of the thermodynamic cycle adapted to obtain the efficiency calculated according to step c / , with the temperature level required for the heat supply of the operating system(s) at the terminals of the condenser, e / from the outlet temperature (Tl) of the system, of the thermo- cycle dynamic determined according to step d / and its efficiency calculated according to step c / , configuration and sizing of the secondary circuit and determination of the temperature of the fluid at the inlet of the intermediate exchanger, f / from the temperature of the fluid at the inlet of the intermediate exchanger determined according to step d, configuration and sizing of the primary circuit.

2. Method according to claim 1, step b / being carried out considering that the thermal and electrical powers required by the system are equal respectively to the thermal power at the terminals of the condenser, supplied by the secondary circuit and the electrical power delivered by the alternator.

3. Method according to claim 1 or 2, the nuclear reactor being a pressurized water reactor (PWR) and the thermodynamic cycle of the secondary circuit being a Rankine cycle.

4. Method according to claim 1 or 2, the nuclear reactor being a fast neutron reactor (RNR) and the thermodynamic cycle of the secondary circuit being able to be a Rankine or Brayton cycle.

5. Method according to claim 3 or 4, step f / comprising the dimensioning of the reactor vessel and the fluid line of the primary circuit.

6. Method according to one of the preceding claims, the heat and electricity exploitation system being a system for capturing atmospheric carbon dioxide CO2, and / or desalination of sea water according to a so-called multiple-effect process (MED) or so-called staged expansion distillation process (MSF).

7. Cogeneration installation configured and sized according to the method of one of the preceding claims, free from a cold source of environmental water.

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