Submerged motor pump and nuclear reactor including such a pump

Abstract

A submerged motor pump and a nuclear reactor comprising such a pump. The submerged motor pump comprises: - a bowl (3) with a fluid inlet (5) and a fluid outlet (7); - a pump impeller (9), arranged inside the bowl (3); - a motor casing (11), integral with the bowl (3) and internally delimiting a chamber (13) in fluidic communication with the bowl (3); - a motor (15) comprising a rotor (17) and a stator (19), arranged inside the chamber (13); - a shaft (21) on which the pump impeller (9) is fixed, the shaft (21) being driven in rotation about an axis of rotation by the rotor (17); - a heat exchanger (41) arranged inside the chamber (13), with a first side (43) in which the fluid circulates and a second side (45) in which a heat transfer fluid circulates;- an engine cooling circuit (47) with the fluid, with a cooling passage (49) along which the fluid flows in thermal contact with the engine (15), the first side (43) of the heat exchanger (41) forming part of the cooling circuit (47) and being arranged downstream of the cooling passage (49). Figure for the abbreviation: 1;

Description

Title of the invention: Submerged motor pump and nuclear reactor comprising such a pump

[0001] The invention relates generally to pumps with a submerged motor.

[0002] A nuclear reactor of the SMR (Small Modular Reactor) type Modular) can be equipped with a primary pump with a submerged motor, intended to circulate the primary fluid in the reactor vessel.

[0003] When such a primary pump is arranged in the lower part of the nuclear reactor, specific constraints must be respected regarding the maximum flow rate allowed in the event of a leak.

[0004] In particular, for the primary fluid circulation conduits, there must not be any breakable conduits with a diameter greater than 4 mm in the pump.

[0005] In a primary pump with a submerged motor, the heat released by the electric motor and the mechanical losses due to the rotating parts in the water are dissipated by circulating the primary fluid within the outer casing in which the motor is housed. This primary fluid must itself be cooled by circulation in a heat exchanger. In the heat exchanger, the heated primary fluid is brought into contact with a heat transfer fluid.

[0006] In such a primary pump, it is possible to arrange the heat exchanger around the outer casing. In this case, the primary fluid circulation side of the heat exchanger is connected to the outer casing by conduits having an internal diameter of approximately 20 mm. These conduits are welded to the pump's outer casing and are therefore classified as breakable elements.

[0007] Such an arrangement therefore does not comply with the safety constraints to be respected for primary pumps located in the lower part of the nuclear reactor.

[0008] In this context, the invention aims to provide a pump that does not have the above-mentioned defect.

[0009] To this end, the invention relates to a pump with a submerged motor for a fluid, comprising: - a bowl with a fluid inlet and a fluid outlet;

[0010] - a pump wheel, arranged inside the bowl;

[0011] - an engine casing, integral with the bowl and internally delimiting a chamber in fluidic communication with the bowl;

[0012] - a motor comprising a rotor and a stator, arranged inside the chamber; - a shaft on which the pump wheel is fixed, the shaft being driven in rotation around an axis of rotation by the rotor;

[0013] - a heat exchanger arranged inside the chamber, with a first side one side through which the fluid circulates and a second side through which a heat transfer fluid circulates; - an engine cooling circuit using fluid, with a cooling passage along which the fluid circulates in thermal contact with the engine, the first side of the heat exchanger being part of the cooling circuit and being arranged downstream of the cooling passage.

[0014] Because the heat exchanger is arranged inside the chamber delimited by the engine casing, there is no duct outside the engine casing for fluid circulation between the exchanger and said chamber. Fluid circulation for engine cooling occurs entirely within the engine casing. This casing is a non-breakable element. This therefore allows the requirement for maximum leakage rate to be met.

[0015] The pump with a submerged motor may further have one or more of the following characteristics, considered individually or according to all technically possible combinations:

[0016] - the engine casing includes a ferrule placed around the engine, the heat exchanger heat being arranged radially between the motor and the ferrule;

[0017] - the heat exchanger comprises a cylindrical membrane having axially towards the pump wheel one proximal end and axially opposite the pump wheel one distal end, the cylindrical membrane having an external passage for the heat transfer fluid on a radially external face and an internal passage for the fluid on a radially internal face;

[0018] - the external passage includes at least one external helical groove cut into the radially external face, and / or the internal passage includes at least one internal helical groove cut into the radially internal face;

[0019] - the proximal end and the distal end of the cylindrical membrane are welded to an internal surface of the engine casing to fluidly isolate the external passage from the internal passage;

[0020] - the pump comprises a stator frame, with a metal jacket lindrique interposed radially between the radially internal face of the cylindrical membrane and the stator, and closing the internal passage on a radially internal side;

[0021] - the stator frame comprises a proximal support ring and a ring distal support arranged axially on either side of the motor, rigidly fixed to two opposite ends of the metal casing, one slice of the proximal support ring and one slice of the distal support ring being pressed against the radially internal face of the cylindrical membrane respectively at the proximal end and the distal end;

[0022] - the one or each external helical groove has a first external depth in an axially central portion of the cylindrical membrane and a second external depth lower than the first external depth at the proximal and distal ends of the cylindrical membrane; and / or

[0023] the or each internal helical groove has a first internal depth in an axially central portion of the cylindrical membrane and a second internal depth lower than the first internal depth at the level of the proximal end and at the level of the distal end of the cylindrical membrane;

[0024] - a distal volume is delimited between the distal support ring and a distal bottom of the motor casing, the distal support ring comprising at its periphery a plurality of orifices fluidly connecting the distal volume with the internal passage;

[0025] - the pump includes a fluid circulation device along the circuit of engine cooling, integral with the shaft and housed in the distal volume;

[0026] - the pump includes:

[0027] * a proximal bearing with a fixed proximal ring mounted on the support ring proximal and a proximal rotating ring fixed to the shaft;

[0028] * a distal bearing with a fixed distal ring mounted on the distal support ring and a distal rotating ring fixed to the shaft,

[0029] the cooling passage comprising a proximal volume located axially between the proximal support ring and a proximal bottom of the motor casing, a proximal intermediate volume located axially between the proximal bearing and the rotor, an air gap between the rotor and the stator, a distal intermediate volume located between the rotor and the distal bearing, and the distal volume;

[0030] - the proximal fixed ring and / or the proximal rotating ring include passages for the circulation of fluid from the proximal volume to the proximal intermediate volume, the distal fixed ring and / or the distal rotating ring including passages for the circulation of fluid from the distal intermediate volume to the distal volume;

[0031] - the pump includes a heat transfer fluid inlet and a heat transfer fluid outlet fluid transfer fluids connected to the second side of the heat exchanger, the heat transfer fluid inlet being intended to be connected to a heat transfer fluid supply line, the heat transfer fluid outlet being intended to be connected to a heat transfer fluid discharge line, the pump comprising an inlet shut-off device configured to selectively isolate or connect the heat transfer fluid inlet and the heat transfer fluid supply line and / or an outlet shut-off device configured to selectively isolate or connect the heat transfer fluid outlet and the heat transfer fluid discharge line.

[0032] According to a second aspect, the invention relates to a nuclear reactor comprising:

[0033] - a core, comprising nuclear fuel assemblies;

[0034] - a pressure vessel containing the core, the pressure vessel being filled by a primary heat transfer fluid up to a nominal level;

[0035] - at least one primary pump having the above characteristics, arranged to circulate the primary heat transfer fluid in the core, raised to a level less than or equal to said nominal level.

[0036] The nuclear reactor may also have one or more of the following characteristics, considered individually or in all technically possible combinations:

[0037] - the primary pump is mounted on the pressure vessel, the shell being placed at the outside of the pressure vessel, the pump wheel being placed inside the pressure vessel.

[0038] Other features and advantages of the invention will become apparent from the detailed description given below, by way of example and not limitation, with reference to the accompanying figures, among which: - [Fig. 1] The [Fig. 1] is an axial cross-sectional view of the pump with a submerged motor of the invention; - [Fig.2][Fig.3] Figures 2 and 3 are enlarged views of two details II and III of the [Fig.l]; - [Fig. 4] Fig. 4 is an exploded, perspective view of the motor pump drowned in [Fig. 1]; and - [Fig.5] [Fig.5] is a schematic representation, in axial section, of a nuclear reactor equipped with primary pumps according to figures 1 to 4.

[0039] The pump with a submerged motor in [Fig.1] is intended to set a fluid in motion.

[0040] In one embodiment, the pump with a submerged motor is intended to circulate the primary fluid of an SMR type nuclear reactor.

[0041] The primary fluid is circulated by the submerged motor pump 1 inside the pressure vessel, which contains the core of the nuclear reactor. The primary fluid flows through the core of the nuclear reactor, then passes through a steam generator, and then reaches the suction inlet of the submerged motor pump 1. The submerged motor pump 1 delivers the primary fluid back into the pressure vessel of the nuclear reactor.

[0042] The submerged motor pump is, for example, located in the lower part of the nuclear reactor, i.e., at the same level as the reactor pressure vessel or at a lower level. For example, it is mounted below the nominal primary fluid level of the pressure vessel.

[0043] The alternatively submerged motor pump is used to circulate a fluid that is not not the primary fluid of the nuclear reactor. According to another variant, it is used in a nuclear reactor of a different type than SMR reactors, or is used in any other industrial installation that is not a nuclear reactor.

[0044] As seen in [Fig.1], the submerged motor pump 1 comprises a bowl 3 with a fluid inlet 5 and a fluid outlet 7, and a pump impeller 9 arranged inside the bowl 3. The fluid inlet constitutes the suction of the pump and the fluid outlet 7 corresponds to the discharge of the pump.

[0045] The pump with a submerged motor 1 is advantageously of the centrifugal type, the fluid inlet 5 being axial and the fluid outlet 7 being radial.

[0046] The pump 1 further comprises a motor casing 11, integral with the bowl 3 and internally delimiting a chamber 13 in fluidic communication with the bowl 3.

[0047] The pump with a submerged motor 1 further comprises a motor 15 with a rotor 17 and a stator 19, arranged inside the chamber 13.

[0048] The pump with a submerged motor 1 also includes a shaft 21 on which the pump wheel 9 is fixed, the shaft 21 being driven in rotation around an axis of rotation X by the rotor 17.

[0049] The pump wheel 9 is rigidly fixed to a proximal end 23 of the shaft 21.

[0050] The proximal end 23 protrudes axially outside the motor housing 11, and is housed inside the bowl 3.

[0051] The rotor 17 is directly fixed on the shaft 21.

[0052] The stator 19 is arranged around the rotor 17, with an air gap 25 separating the stator from the rotor.

[0053] The rotor 17 and the stator 19 are cylindrical in shape, and are coaxial with the axis of rotation X.

[0054] The motor housing 11 has a ferrule 27 placed around the motor 15. The ferrule is cylindrical, coaxial with the X axis.

[0055] The motor housing 11 further includes a distal bottom 29, sealing a distal end of the ferrule 27 in a fluid-tight manner. The distal end corresponds to the end located axially opposite the pump wheel 9.

[0056] The motor housing 11 has an extension 31, extending the ferrule 27 axially towards the pump wheel 9. The extension 31 has a flange 33 for fixing to the proximal end of the ferrule 27. The extension 31 is tubular, coaxial with the X axis.

[0057] The motor housing 11 also includes a proximal bottom 35 closing the extension 31 axially towards the pump wheel 9.

[0058] The bowl 3 is integral with the proximal bottom 35. The shaft 21 exits the chamber 13 through an opening 37 provided in the center of the proximal bottom 35. The chamber 13 is in fluidic communication with the bowl 3 through the opening 37. The fluid can flow along the shaft 21 between the inside of the bowl 3 and the inside of the chamber 13.

[0059] The pressures inside the bowl 3 and inside the chamber 13 are substantially equal.

[0060] A thermal barrier 39 is arranged in the chamber 13 along the shaft section 21 adjoining the opening 37. The thermal barrier 39 occupies one end of the extension 31.

[0061] The pump with a submerged motor 1 further includes a heat exchanger 41 arranged inside the chamber 13, with a first side 43 in which the fluid circulates and a second side 45 in which a heat transfer fluid circulates.

[0062] The fluid circulating on the first side 43 and the heat transfer fluid circulating on the second side 45 are in thermal contact with each other through the wall of the heat exchanger 4L

[0063] The pump with a submerged motor 1 also includes a motor cooling circuit 47 with the fluid, with a cooling passage 49 along which the fluid circulates in thermal contact with the motor 15.

[0064] The first side 43 of the heat exchanger is part of the engine cooling circuit 47, and is arranged downstream of the cooling passage 49.

[0065] The heat exchanger 41 is arranged radially between the motor 15 and the ferrule 27.

[0066] More specifically, the heat exchanger 41 comprises a cylindrical membrane 51 having an external passage for the heat transfer fluid on a radially external face 53, and an internal passage for the fluid on a radially internal face 55.

[0067] The cylindrical membrane 51 is coaxial with the X axis. It is made of a metal that conducts heat well, for example stainless steel.

[0068] It has a proximal end 57 turned axially towards the pump wheel 9, and a distal end 59 axially opposite the pump wheel 9.

[0069] The internal passage constitutes the first side 43 of the heat exchanger. The external passage constitutes the second side 45 of the heat exchanger.

[0070] The external passage includes at least one external helical groove 61 cut into the radially external face 53 of the cylindrical membrane.

[0071] Typically, it comprises a plurality of external helical grooves 61 arranged parallel to each other in the radially external face 53. In the example shown, the external passage comprises twelve external helical grooves 61.

[0072] The external helical groove or grooves 61 wrap around the axis X, and extend over the entire axial length of the cylindrical membrane 51, from the proximal end 57 to the distal end 59.

[0073] Similarly, the internal passage includes at least one internal helical groove 63 cut into the radially internal face 55.

[0074] Preferably, the internal passage comprises a plurality of helical grooves internal 63, arranged parallel to each other. In the example shown, the internal passage has twelve internal helical grooves 63.

[0075] The internal helical groove or groove 63 wraps around the axis X, and extends along the entire axial length of the cylindrical membrane 51, from the proximal end 57 to the distal end 59.

[0076] The external helical groove or each external helical groove 61 has a first external depth in an axially central portion of the cylindrical membrane 51, and a second external depth lower than the first external depth at the proximal end 57 and at the distal end 59.

[0077] The first depth is greater than 50% of the thickness of the cylindrical membrane 51, preferably greater than 75% of the thickness of the cylindrical membrane.

[0078] At the proximal and distal ends of the cylindrical membrane, the depth of the external helical groove 61 gradually decreases. Thus, the last turn of the external helical groove 61 is very shallow, the penultimate turn is slightly deeper, etc.

[0079] Similarly, the internal helical groove 63 has a first internal depth in an axially central portion of the cylindrical membrane 51 and a second internal depth lower than the first internal depth at the proximal end 57 and at the distal end 59 of the cylindrical membrane 51.

[0080] As can be seen in Figures 2 and 3, the first internal depth is greater than 50% of the thickness of the cylindrical membrane 51, preferably greater than 75% of the thickness of the cylindrical membrane 51.

[0081] The internal helical groove 63 at the proximal end 57 and at the distal end 59 has a depth that gradually decreases.

[0082] As can be seen in [Fig. 3], at the distal end 59, the last turn of the internal helical groove 63 has a very shallow depth. The penultimate turn has a slightly greater depth, etc.

[0083] At the proximal end 57, the depth of the internal helical groove 63 decreases only slightly, and remains, for example, greater than 50% of the thickness of the cylindrical membrane 51 at the level of the last turn ([Fig.2]).

[0084] Thus, in its central portion, the cylindrical membrane 51, viewed in section in a plane containing the X-axis, has a sinuous shape with a constant wall thickness. Each turn of an internal helical groove 63 is framed by two turns belonging to external helical grooves 61 (see Figures 2 and 3). This makes it possible to obtain excellent heat transfer coefficients in the heat exchanger between the fluid and the heat transfer fluid.

[0085] The proximal end 57 and the distal end 59 of the cylindrical membrane 51 are welded to the internal surface of the motor housing 11 to fluidly isolate the external passage from the internal passage.

[0086] More specifically, and as illustrated in [Fig.2], a lip 65 is formed on the radially external face 53 of the cylindrical membrane 51. This lip 65 is welded by an invisible weld bead to a complementary lip 67, formed on the internal surface of the envelope 11. The two lips 65, 67 are substantially cylindrical, the lip 67 being placed radially around the lip 65.

[0087] At the distal end 59, a lip 69 is formed on a radially internal face 55 of the cylindrical membrane 51. It is welded by a weld bead 71 to a complementary lip 73 formed on the internal surface of the envelope. Lips 69 and 73 are substantially annular. Lip 73 is axially adjacent to lip 69.

[0088] The pump 1 further comprises a stator frame 75, with a cylindrical metal sleeve 77 interposed radially between the radially internal face 55 of the cylindrical diaphragm 51 and the stator 19.

[0089] The metal jacket 77 is made of a material having a good coefficient of heat transfer by conduction, for example stainless steel.

[0090] The central portion of the cylindrical membrane 51 corresponds to the part of the cylindrical membrane 51 pressed against the jacket 77. It covers at least 70% of the axial length of the cylindrical membrane, preferably at least 80% of the axial length of the cylindrical membrane.

[0091] The stator frame 75 further includes a proximal support ring 79 and a distal support ring 81 arranged axially on either side of the motor 15, rigidly fixed to two opposite axial ends of the metal jacket 77.

[0092] A slice of the proximal support ring 79 is pressed against the radially internal face 55 of the cylindrical membrane 51 at the proximal end 57. In the same way, a slice of the distal support ring 81 is pressed against the radially internal face 55 of the cylindrical membrane 51 at the distal end 59.

[0093] Thus, the edges of the support rings 79, 81 are pressed against areas of the radially internal surface 55 in which the internal helical groove(s) 63 are shallower. These areas therefore exhibit higher mechanical resistance than the central portion.

[0094] The stator frame 75 further comprises two closing plates 83, arranged on radially internal edges of the proximal support ring 79 and the distal support ring 81. The plates 83 close on a radially internal side the volume located between the ring 79 and the stator 19 and the volume located between the stator 19 and the ring 81.

[0095] The stator buns 84 are housed in these volumes, and are isolated from the fluid by the closing plates 83, support rings 79, 81, and by the metal sleeve 77.

[0096] As can be seen in particular on [Fig.3], a distal volume 85 is delimited between the distal support ring 81 and the distal bottom 29 of the motor housing 11.

[0097] Figure 4 shows that the distal support ring 81 comprises at its periphery a plurality of orifices 87 fluidly connecting the distal volume 85 with the internal passage.

[0098] The orifices 87 are distributed around the periphery of the distal support ring 81. They are machined on the edge, i.e., on the radially external surface, of the ring 81. They are axially open at one end so as to open into the distal volume 85. They are axially closed at the opposite end. They are radially open outwards so as to communicate with the internal helical groove(s) 63.

[0099] The pump 1 further includes a component 89 for circulating the fluid along the cooling circuit of the engine 47.

[0100] This organ 89 is integral with the shaft 21 and is housed in the distal volume 85. Thus, it is driven in rotation with the shaft 21.

[0101] In the example shown, the component 89 is a disc having a plurality of radial bores 90R, opening at the level of a radially external slice of the disc.

[0102] The component 89 also includes a plurality of axial bores 90A, each opening at its two ends at the two large opposite faces of the disc. Each radial bore 90R opens, at an internal end opposite the radially external edge of the disc, into one of the axial bores 90A.

[0103] The component 89 thus performs the function of a pump in the engine cooling circuit. The radial bores generate the pumping effect by imparting kinetic energy to the fluid. The axial bores supply fluid to the radial bores.

[0104] As an alternative and / or in addition, the component 89 includes, for example, blades of the type used for centrifugal pumps in order to improve hydraulic efficiency.

[0105] The circulation device 89 expels the fluid radially outwards, to the orifices 87.

[0106] As can be seen in [Fig. 1], pump 1 further comprises:

[0107] - a proximal bearing 91, with a fixed proximal ring 93 mounted on the ring of proximal support 79 and a proximal rotating ring 95 integral with the shaft 21;

[0108] - a distal bearing 97, with a distal fixed ring 99 mounted on the support ring distal 81 and a distal rotating ring 101 integral with the shaft 21.

[0109] The motor 15 is located axially between the two bearings.

[0110] The cooling passage 49 comprises a proximal volume 103 located axially between the proximal support ring 79 and the proximal bottom 35 of the motor housing 11, a proximal intermediate volume 105 located axially between the proximal bearing 91 and the rotor 17, the air gap 25 between the rotor and the stator, and a distal intermediate volume 107 located between the rotor 17 and the distal bearing 97. The cooling passage 49 further comprises the distal volume 85.

[0111] The proximal volume 103 is axially delimited on one side by the proximal support ring 79 and the proximal bearing 91. It is axially delimited on the opposite side by the thermal barrier 39. It is located inside the extension 31.

[0112] In order to permit circulation between volumes 103 and 105, the proximal fixed ring 93 and / or the proximal rotating ring 95 include passages 109 for the circulation of fluid from the proximal volume 103 to the proximal intermediate volume 105.

[0113] Similarly, the fixed distal ring 99 and / or the rotating distal ring 101 include passages 111 for the circulation of fluid from the distal intermediate volume 107 to the distal volume 85.

[0114] The pump 1 further includes a heat transfer fluid inlet 113 and a heat transfer fluid outlet 115 fluidically connected to the second side 45 of the heat exchanger 4L. The inlet 113 and the outlet 115 are for example provided in the motor casing 11.

[0115] The pump 1 also includes an inlet manifold 117 and an outlet manifold 119 fluidically connected respectively to the inlet 113 and the outlet 115.

[0116] The inlet collector 117 is a groove cut into the inner surface of the ferrule 27. It is located opposite the proximal end 57 of the cylindrical membrane 51. The outlet collector 119 is a groove cut into the inner surface of the ferrule 27. It is located opposite the distal end 59 of the cylindrical membrane 51.

[0117] Alternatively, the inlet collector is on the distal side of the cylindrical membrane, and the outlet collector is on the proximal side.

[0118] The radially external surface 53 of the cylindrical membrane 51 is pressed against the internal surface of the ferrule 27. The external helical groove or grooves 61 at one end therefore open into the inlet groove 117. The external helical groove or grooves 61 at its opposite end open into the outlet groove 119.

[0119] The radially internal surface of the ferrule 27 closes the external passage on a radially external side, except at the grooves 117 and 119.

[0120] The sleeve 77, for its part, closes the internal passage on a radially internal side.

[0121] More specifically, it closes the central part of the internal passage.

[0122] The slices of the proximal and distal support rings 79, 81 partially close the internal passage at the proximal end 57 and at the end distal 59 of the cylindrical membrane. At the proximal end 57, the internal passage communicates with the proximal volume 103, the last turns of the or each internal helical groove 63 extending beyond the proximal support ring 79 and therefore not being covered by the edge of this ring.

[0123] The heat transfer fluid inlet 113 is intended to be connected to a heat transfer fluid supply line 121. The heat transfer fluid outlet 115 is intended to be connected to a heat transfer fluid discharge line 123.

[0124] The pump further includes an inlet shut-off device 125 configured to selectively isolate or connect the heat transfer fluid inlet 113 and the heat transfer fluid supply line 121, and / or an outlet shut-off device 127 configured to selectively isolate or connect the heat transfer fluid outlet 115 and the heat transfer fluid discharge line 123.

[0125] The inlet shut-off element 125 is for example an on / off valve.

[0126] The outlet shut-off device 127 is for example an on / off valve.

[0127] The operation of the pump described above will now be detailed.

[0128] When the pump is running, the chamber 13 delimited by the motor casing is filled with fluid. This fluid is in pressure equilibrium with the internal volume of the bowl 3.

[0129] When the rotor 17 drives the pump wheel 9 in rotation, the circulation element 89 is also set in rotation. This causes the fluid to circulate inside the chamber 13 along the engine cooling circuit 47.

[0130] The fluid flows in the cooling passage 49 from the proximal volume 103 to the proximal intermediate volume 105, through the passages 109 and also between the rings 93 and 95.

[0131] From the proximal intermediate volume 105, the fluid flows to the distal intermediate volume 107 along the air gap 25. In doing so, it cools the rotor 17 and the stator 19.

[0132] The fluid flows from the distal intermediate volume 107 to the distal volume 85 through the passages 111 and between the rings 99 and 101.

[0133] Within the distal volume 85, the fluid flows into the channels of the circulatory organ 89 and is propelled to the orifices 87.

[0134] The fluid then enters the internal passage of the heat exchanger 41, that is, the first side 43 of the heat exchanger. It flows from the distal end 59 to the proximal end 57 of the cylindrical membrane 51, following the internal helical channel(s) 63.

[0135] Having reached the proximal end 57 of the cylindrical membrane, it returns to the proximal volume 103.

[0136] During its passage through the internal helical channel(s) 63, the fluid is in thermal contact both with the jacket 77 and with the heat transfer fluid flowing from the second side 45 of the heat exchanger 41.

[0137] The heat transfer fluid enters the pump through the inlet 113, and is directed to the inlet groove 117. It flows from the inlet groove 117 into the external passage, and more specifically follows the external helical channel(s) 61. It is collected in the outlet groove 119 and flows from there to the fluid outlet 115.

[0138] The nuclear reactor 129 shown in [Fig. 5] comprises:

[0139] - a core 131, comprising nuclear fuel assemblies;

[0140] - a pressure vessel 133, containing the core 131, the pressure vessel 133 being filled with a primary heat transfer fluid up to a nominal level;

[0141] - at least one primary pump 135, arranged to circulate the heat transfer fluid primary in the heart 131.

[0142] Nuclear reactor 129 is of the integrated type. For example, it is an SMR.

[0143] It includes steam generators 137 housed in the pressure vessel 133.

[0144] The core 131 is placed in the lower part of the pressure vessel 133. The steam generators 137 are housed above the core 131.

[0145] The nuclear reactor 129 also includes a pressurizer 139 delimited inside the vessel head 141.

[0146] The primary pump(s) 135 is arranged to circulate the primary heat transfer fluid inside the pressure vessel 133 in a loop. The primary heat transfer fluid passes through the core 131, then circulates through the steam generators 137, and is then returned by the primary pump(s) 135 to the core 131.

[0147] In the example shown, the nuclear reactor includes several primary pumps 135, for example six primary pumps.

[0148] The primary pump or pumps 135 are a wet motor pump of the type described above.

[0149] The primary pump or pumps 135 are mounted at a level lower than or equal to said nominal level of primary heat transfer fluid of the pressure vessel 133.

[0150] The nominal level of primary heat transfer fluid in the pressure vessel 133 corresponds, for example, substantially to the level of the contact plane between the flange of the pressure vessel and the cover 141.

[0151] The primary pump or pumps 135 are preferably mounted in the vertical direction between the core 131 and the steam generators 137. The vertical direction corresponds substantially to the axis of the pressure vessel 133.

[0152] The primary pump or pumps 135 are mounted on the pressure vessel 133, the ferrule 27 being placed outside the pressure vessel 133, the pump wheel 9 being placed inside the pressure vessel 133.

[0153] The primary pump or pumps 135 are mounted with their axis of rotation horizontal, The axis of rotation is typically radial with respect to the central axis of the pressure vessel.

[0154] A radially external fixing flange 143 is formed at the proximal end of the ferrule 27. It is directly fixed to the pressure vessel 133. The extension 31 is engaged in an opening provided in the pressure vessel 133.

[0155] The pump described above has multiple advantages.

[0156] Arranging the heat exchanger radially between the engine and the engine casing shell allows the heat exchanger to be housed very conveniently within the engine casing. This arrangement provides a large contact area between the fluid and the heat transfer fluid.

[0157] When the heat exchanger comprises a cylindrical membrane having an external passage for the heat transfer fluid on a radially external face and an internal passage for the fluid on a radially internal face, the heat exchange between the fluid and the heat transfer fluid is carried out through the cylindrical membrane. This is particularly convenient for housing the heat exchanger inside the engine casing and organizing fluid circulation, without excessively increasing the pump's size.

[0158] When the external passage includes at least one external helical groove cut into the radially external face and / or the internal passage includes at least one internal helical groove cut into the radially internal face, the external and internal passages are made in a particularly compact manner, with particularly good heat exchange between the two passages.

[0159] Welding the cylindrical membrane to the internal surface of the motor casing at both ends makes it possible to conveniently achieve fluidic isolation between the external passage and the internal passage.

[0160] When the pump comprises a stator housing with a cylindrical metal jacket interposed radially between the radially inner face of the cylindrical diaphragm and the stator, and closing the internal passage on one radially inner side, the heat dissipated by the stator is transmitted by conduction directly into the fluid flowing in the internal passage. This optimizes the cooling of the stator.

[0161] Because the stator frame has a proximal support ring and a distal support ring arranged axially on either side of the motor, rigidly fixed to two opposite ends of the metal jacket, a slice of the proximal support ring and a slice of the distal support ring being pressed against the radially internal surface of the cylindrical membrane respectively at the proximal end and the distal end, the membrane is held in position by the support rings.

[0162] When the external helical groove has a first external depth in an axially central portion of the cylindrical membrane and a second external depth lower than the first external depth at the proximal end and at the distal end of the cylindrical membrane, the cylindrical membrane is mechanically more resistant at both ends and can withstand the pressure exerted by the support rings.

[0163] Similarly, when the internal helical groove has a first internal depth in an axially central portion of the cylindrical membrane and a second internal depth lower than the first internal depth at the proximal end and at the distal end of the cylindrical membrane, the membrane is mechanically more resistant at both ends and can withstand the pressure exerted by the support rings.

[0164] When the distal support ring has at its periphery a plurality of orifices fluidly connecting the distal volume with the internal passage, the connection of the distal volume with the internal passage is achieved in a simple and convenient manner.

[0165] When the pump includes a fluid circulation element along the cooling circuit attached to the shaft and housed in the distal volume, the circulation of the fluid along the engine cooling circuit is achieved particularly simply.

[0166] When the proximal bearing has a fixed proximal ring and / or a rotating proximal ring with passages for fluid circulation, fluid circulation along the cooling passage is promoted. Similarly, when the distal bearing has a fixed distal ring and / or a rotating distal ring with passages for fluid circulation, fluid circulation is promoted along the cooling passage.

[0167] When the pump includes an inlet shut-off device configured to selectively isolate or connect the heat transfer fluid inlet and the heat transfer fluid supply line, and / or an outlet shut-off device configured to selectively isolate or connect the heat transfer fluid outlet and the heat transfer fluid discharge line, in the event of a heat exchanger rupture, the breach can be isolated from the heat transfer fluid supply line and / or the heat transfer fluid discharge line. The shut-off devices are designed to withstand the pressure of the primary fluid.

[0168] The pump can have multiple variants.

[0169] The pump is not necessarily of the centrifugal type, but can be of any suitable type.

[0170] The fluid inlet into the bowl is not necessarily axial and the fluid outlet is not necessarily radial.

[0171] The bowl could be attached directly to the ferrule of the motor casing, without the interposition of an extension.

[0172] The rotor is not necessarily directly mounted on the shaft, the shaft may for example be driven by the rotor via a reducer.

[0173] The external passage may include non-helical grooves of any other suitable shape: straight, sinuous, etc.

[0174] The external passage can be achieved by means other than one or more grooves cut into the cylindrical membrane. For example, one or more grooves can be cut into the inner surface of the shell. Ribs delimiting fluid circulation channels can be welded to the external surface of the cylindrical membrane.

[0175] Similarly, the internal passage may include non-helical grooves of any other suitable shape: straight, sinuous, etc.

[0176] The internal passage can be achieved by means other than one or more grooves cut into the cylindrical diaphragm. For example, one or more grooves can be cut into the external surface of the stator jacket. Ribs delimiting fluid circulation channels can be welded to the internal surface of the cylindrical diaphragm.

[0177] The heat exchanger can also be made in the form of a thicker cylindrical membrane with axial perforations. The fluid flows through one part of the axial perforations and the heat transfer fluid through another part of the axial perforations.

Claims

Demands

1. A wetted motor pump for a fluid, comprising: - a bowl (3) with a fluid inlet (5) and a fluid outlet (7); - a pump impeller (9), arranged inside the bowl (3); - a motor casing (11), integral with the bowl (3) and internally delimiting a chamber (13) in fluidic communication with the bowl (3); - a motor (15) comprising a rotor (17) and a stator (19), arranged inside the chamber (13); - a shaft (21) on which the pump impeller (9) is fixed, the shaft (21) being driven in rotation about an axis of rotation by the rotor (17); - a heat exchanger (41) arranged inside the chamber (13), with a first side (43) in which the fluid circulates and a second side (45) in which a heat transfer fluid circulates;- an engine cooling circuit (47) by the fluid, with a cooling passage (49) along which the fluid flows in thermal contact with the engine (15), the first side (43) of the heat exchanger (41) forming part of the cooling circuit (47) and being arranged downstream of the cooling passage (49).;

2. Pump according to claim 1, wherein the motor casing (11) comprises a ferrule (27) placed around the motor (15), the heat exchanger (41) being arranged radially between the motor (15) and the ferrule (27).

3. Pump according to claim 2, wherein the heat exchanger (41) comprises a cylindrical membrane (51) having axially towards the pump wheel (9) a proximal end (57) and axially opposite the pump wheel (9) a distal end (59), the cylindrical membrane (51) having an external passage for the heat transfer fluid on a radially external face (53) and an internal passage for the fluid on a radially internal face (55).

4. Pump according to claim 3, wherein the external passage comprises at least one external helical groove (61) cut into the radially external face (53), and / or the internal passage comprises at least one internal helical groove (63) cut into the radially internal face (55).

5. Pump according to claim 3 or 4, wherein the proximal end (57) and the distal end (59) of the cylindrical diaphragm (51) are welded to an internal surface of the motor casing (11) to fluidly isolate the external passage from the internal passage.

6. Pump according to any one of claims 3 to 5, wherein the pump (1) comprises a stator frame (75), with a cylindrical metal jacket (77) interposed radially between the radially internal face (55) of the cylindrical diaphragm (51) and the stator (19), and closing the internal passage on a radially internal side.

7. Pump according to claim 6, wherein the stator frame (75) comprises a proximal support ring (79) and a distal support ring (81) arranged axially on either side of the motor (15), rigidly fixed to two opposite ends of the metal jacket (77), a slice of the proximal support ring (79) and a slice of the distal support ring (81) being pressed against the radially internal face (55) of the cylindrical membrane (51) respectively at the proximal end (57) and the distal end (59).

8. Pump according to claim 7 combined with claim 4, wherein the external helical groove or each external helical groove (61) has a first external depth in an axially central portion of the cylindrical membrane (51) and a second external depth lower than the first external depth at the proximal end (57) and at the distal end (59) of the cylindrical membrane (51); and / or the internal helical groove or each internal helical groove (63) has a first internal depth in an axially central portion of the cylindrical membrane (51) and a second internal depth lower than the first internal depth at the proximal end (57) and at the distal end (59) of the cylindrical membrane (51).

9. Pump according to claim 7 or 8, in which a distal volume (85) is delimited between the distal support ring (81) and a distal bottom (29) of the motor housing (11), the distal support ring (81) comprising at its periphery a plurality of orifices (87) fluidly communicating the distal volume (81) with the internal passage.

10. Pump according to claim 9, wherein the pump (1) comprises a fluid circulation element (89) along the engine cooling circuit (47), integral with the shaft (21) and housed in the distal volume (85).

11. Pump according to any one of claims 7 to 10, in which

12.

13.

14. The pump (1) includes: - a proximal bearing (91) with a fixed proximal ring (93) mounted on the proximal support ring (79) and a rotating proximal ring (95) integral with the shaft (21); - a distal bearing (97) with a distal fixed ring (99) mounted on the distal support ring (81) and a distal rotating ring (101) integral with the shaft (21), the cooling passage (49) comprising a proximal volume (103) located axially between the proximal support ring (79) and a proximal bottom (35) of the motor casing (9), a proximal intermediate volume (105) located axially between the proximal bearing (91) and the rotor (17), an air gap (25) between the rotor (17) and the stator (19), a distal intermediate volume (107) located between the rotor (17) and the distal bearing (81), and the distal volume (85). Pump according to claim 11, wherein the proximal fixed ring (93) and / or the proximal rotating ring (95) comprise passages (109) for the circulation of fluid from the proximal volume (103) to the proximal intermediate volume (105), the distal fixed ring (99) and / or the distal rotating ring (101) comprising passages (111) for the circulation of fluid from the distal intermediate volume (107) to the distal volume (85).A pump according to any one of claims 1 to 12, wherein the pump comprises a heat transfer fluid inlet (113) and a heat transfer fluid outlet (115) fluidically connected to the second side (45) of the heat exchanger (41), the heat transfer fluid inlet (113) being provided for connection to a heat transfer fluid supply line (121), the heat transfer fluid outlet (115) being provided for connection to a heat transfer fluid discharge line (123), the pump comprising an inlet shut-off device (125) configured to selectively isolate or connect the heat transfer fluid inlet (113) and the heat transfer fluid supply line (121) and / or an outlet shut-off device (127) configured to selectively isolate or connect the heat transfer fluid outlet (115) and the fluid discharge line heat transfer fluid (123). Nuclear reactor (129) comprising: - a core (131), comprising nuclear fuel assemblies; - a pressure vessel (133), containing the core (131), the pressure vessel (133) being filled with a primary heat transfer fluid up to a nominal level; - at least one primary pump (135) according to any one of claims 1 to 13, arranged to circulate the primary heat transfer fluid in the core (1), mounted at a level lower than or equal to said nominal level.

15. Nuclear reactor according to claim 14, in which the primary pump (135) is mounted on the pressure vessel (133), the shell (27) being placed outside the pressure vessel (33), the pump wheel (9) being placed inside the pressure vessel (133).

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