The present invention relates to a device for subjecting probes to irradiation in the core of a heavy water nuclear reactor, in particular of a CANDU reactor, a diverter, an installation for producing activated probes in the core of the heavy water reactor and a heavy water reactor.

Heavy water type nuclear power plants, specifically CANDU pressurized heavy water reactors, have a very high thermal neutron flux and a high level epithermal neutron flux over a wide range of resonance that is capable of activating non-uranium based targets with neutron capture. Such neutron capture considerably reduces the waste created to obtain the radioisotopes as well has the capability to produce significant amounts of radioisotopes such as Mo-99 or Lu-177 to replace production from aging research reactors as they are retired.

Several studies have been done looking at modifying CANDU fuel elements contained in the pressure tubes of the primary coolant loop to include irradiation targets allowing production of isotopes. This involves using the on-line fueling machines to insert and retrieve the modified fuel elements, which creates on operational risk to the reactor as the fueling functions place restrictions on the operating units as well may increase the risk of a reactor trip due to inadvertent events. The use of modified fuel elements also requires substantial changes in the plant design to address the modified fuel element and getting the fuel element out of the Spent Fuel Bay for isotope extraction purposes.

WO 2016/207054 A1 describes a device for inserting and retrieving targets into a heavy water type nuclear power plant comprising a guide tube introduced through a free access port allowing access to the core of the nuclear reactor, for example a view port, the access port being located in the reactivity mechanism deck of the nuclear reactor. The guide tube extends into the moderator of the nuclear reactor, and contains a plurality of pressure boundary tubes, intended for receiving the targets in view of their irradiation in the core of the nuclear reactor.

This device is, however, not entirely satisfactory. In particular, due in particular to the Y-shaped geometry of the distributor, which includes the inlet/outlet for the targets on one branch of the Y and the inlet for the gas for pushing the targets out of the device on the other branch of the Y, this device only allows for relatively small bending radii or target geometries. It is therefore only adapted for receiving spherical targets of relatively small diameter. Considering the tight space constraints in this location of the CANDU reactor, it is unlikely that such a design could be used for cylindrical targets having a larger diameter, since this would result in considerably larger dimensions of the device. In addition, the device described in this document cannot be easily lifted out of the port of the reactivity mechanism deck in one piece.

One purpose of the invention is to provide a device which allows for inserting and retrieving a larger variety of probes into and from the core of a heavy water reactor which is easy to handle and is further compact.

For this purpose, the invention relates to a device for subjecting probes to irradiation in the core of a heavy water nuclear reactor, comprising:

- a plurality of probe receiving fingers, each probe receiving finger defining a longitudinal axis, and extending into the core of the nuclear reactor, each probe receiving finger being configured for receiving a plurality of probes in view of their irradiation in the core of the nuclear reactor, and each probe receiving finger having a double walled structure comprising an inner tube and an outer tube, defining an annular space there-between, the inner tube delimiting an inner passage for the circulation of the probes; and

- a pneumatic transport system, configured for supplying a flow of pressurized gas through the inner tube in a first direction for pushing the probes into the probe receiving finger and in a second direction, opposite the first direction, for pushing the probes out of the probe receiving finger, wherein the device further comprises a head, to which the probe receiving fingers are attached, the head comprising a body defining, for each of the probe receiving fingers, a gas conduit for receiving a flow of pressurized gas from the pneumatic transport system, each gas conduit having a first end opening into the annular space between the inner tube and the outer tube of the respective probe receiving finger and a second end connected to a gas supply port for connection to a supply of pressurized gas, the gas conduits of the different probe receiving fingers being separated from each other fluidically.

The device according to the invention is advantageous. Indeed, since the probe receiving fingers are isolated from each other from a fluidic point of view, and further each have their own inlet for pressurized gas, it is possible to insert and remove probes from these different fingers independently, which allows producing different types of isotopes, with different activation times, or to produce the same isotopes sequentially in time in the different probe receiving fingers, such that there are always activated isotopes available. The device therefore results in an improved flexibility with respect to the manufacturing of activated isotopes. In addition, the design of the device is particularly compact and robust. It is therefore particularly adapted for being used in the core of a heavy water reactor, in particular a CANDU reactor, as described above, where the space available is relatively small. In particular, since the device may for example include six probe receiving fingers, a relatively high number of probes may be irradiated simultaneously, thus resulting in an improved productivity.

Furthermore, the device according to the invention allows the insertion of much larger probes than was possible with prior art installations, and in particular of cylindrical probes having a diameter up to 12 mm. Therefore, this device results in an improved productivity, since a greater amount of isotopes may be produced in the device within a given time.

The fact that both spherical and cylindrical probes may be used also increases the flexibility of use of the device.

The compact and stiff design of the device is also advantageous compared to prior art devices, as it results in an increased resistance to earthquakes.

The device may further comprise one or more of the following features, taken alone, or according to any technically possible combination:

- The outer tube is attached to the head through clamping.

- The body comprises an upper part and a lower part, attached to each other, in particular by means of screws, and the outer tube comprises a radial annular flange which is clamped between the upper part and the lower part.

- The device further comprises first seals for pressure-tight sealing of the inner passage of each inner tube and/or second seals for pressure-tight sealing of the annular space between the inner tube and the outer tube.

- The gas supply port is inserted into the gas conduit in a pressure-tight manner.

- The gas conduit comprises a first conduit portion extending perpendicular to the longitudinal axis of the respective probe receiving finger from the first end of the conduit.

- The gas conduit further comprises a second conduit portion extending perpendicular to the first conduit portion, the second conduit portion comprising a first end opening into the first conduit portion and a second end forming the second end of the conduit, the second end of the conduit being located at a top surface of the head.

- The body comprises an upper part and a lower part, attached to each other, in particular by means of screws, the gas conduits being formed in the upper part.

- The device further comprises, for each probe receiving finger, a connection port for connection of the probe receiving finger to a probe handling system for transporting the probes into and/or out of the probe receiving finger, the connection port forming a pressure- tight connection with the probe receiving finger. - The device further comprises a lifting handle, attached to the body of the head, for lifting the device in one piece.

- The pneumatic transport system comprises a dedicated gas supply line for each gas conduit, each gas supply line being connected to the gas supply port of the corresponding gas conduit.

According to another aspect, the invention relates to a diverter for selectively connecting one of a plurality of inlet tubes, each inlet tube being intended to be connected to a respective probe receiving finger intended for receiving probes for their irradiation in the core of a nuclear reactor to one single outlet tube intended to be connected to a probe handling system, said diverter comprising:

- n inlet ports, n being an integer greater than or equal to three, each inlet port comprising an inlet tube fitting, the inlet tube fitting comprising an inlet end connected to a corresponding inlet tube;

- one single outlet port comprising an outlet tube fitting, the outlet tube fitting comprising an outlet end connected to the outlet tube,

- a connection tube comprising an inlet end, connected to an outlet end of one of the inlet tube fittings and an outlet end, connected to an inlet end of the outlet tube fitting, the inlet port to which the connection tube is connected being an active inlet port and the remaining inlet ports being inactive inlet ports; wherein the inlet end of the inlet tube fitting is configured to form a pressure-tight connection with the inlet tube and the outlet end of the inlet tube fitting is configured to form a pressure- tight connection with the inlet end of the connection tube ; and the inlet tube fittings are arranged on at least a portion of a circle, the outlet tube fitting being arranged in the alignment of the center of the circle, taken along a longitudinal direction of the diverter extending perpendicular to the plane of the circle.

The diverter according to the invention is particularly advantageous. Indeed, it allows increasing the irradiation capacities, due to the fact that several probe receiving fingers, and for example six probe receiving fingers, located in the core of the nuclear reactor may be used without having to increase the number of system components for handling the probes located outside of the core of the nuclear reactor. In addition, thanks to the pressuretightness of the connections, in particular on the inlet side, the diverter is integrated into the containment boundary, which makes it possible to avoid the use of containment penetration valves. Indeed, normally, containment penetration valves are located at the containment boundary to prevent primary fluid from exiting the containment in case of a leakage. With the diverter according to the invention, since the connections of the diverter are pressure- tight, there is no risk of primary fluid exiting the containment at the diverter.

The diverter may further comprise one or more of the following features, taken alone, or according to any technically possible combination:

- The diverter further comprises a plurality of closure plugs inserted into the outlet ends of the inlet tube fittings of the inactive inlet ports so as to close these inlet tube fittings in a pressure-tight manner.

This feature contributes to making the diverter part of the containment enclosure. Indeed, since all inactive inlet ports are closed in a pressure-tight manner, there is no risk of primary fluid exiting the containment through these inactive inlet ports in case of a leakage.

- The inlet end of the outlet tube fitting is configured to form a pressure-tight connection with the outlet end of the connection tube and the outlet end of the outlet tube fitting is configured to form a pressure-tight connection with the outlet tube.

- The connection tube is displaceable between n positions, each position corresponding to the connection of the inlet end of the connection tube to the outlet end of one of the n inlet tube fittings and of the outlet end of the connection tube to the inlet end of the outlet tube fitting, wherein, in each position, the inlet port to which the connection tube is connected is an active inlet port and the remaining inlet ports are inactive inlet ports.

- The connection tube is configured to be manually displaceable between the n positions.

- The outlet tube fitting is supported by an outlet support structure, said outlet support structure being displaceable in translation along the longitudinal direction of the diverter.

- The diverter further comprises a detector configured to detect which one of the inlet ports is the active inlet port.

- The detector comprises an inlet plug and socket system comprising:

- an inlet socket for each inlet port, the inlet socket being arranged at the inlet tube fitting of the inlet port, and

- an inlet plug, attached to the inlet end of the connection tube, the detector being configured in such a manner that, when the inlet plug is plugged into the inlet socket of one of the inlet ports, a signal indicative of the fact that the corresponding inlet port is the active inlet port is generated.

- The plug and socket system is configured in such a manner that the inlet plug can only be plugged into the inlet socket of the inlet port to which the inlet end of the connection tube is connected. - The inlet plug is attached to the connection tube through a flexible connection link, for example a chain or a cord, the length of the flexible connection link being chosen in such a manner that the inlet plug can only be plugged into the inlet socket of the inlet port to which the inlet end of the connection tube is connected.

- The plugging of the inlet plug into the inlet socket is configured to close an electric circuit, the closing of the electric circuit resulting in the generation of the signal indicative of the fact that the inlet port at which the inlet socket is located is the active inlet port.

- The detector is further configured for detecting a breakage in a wire of an electric cable arriving at the inlet socket.

- The diverter further comprises an outlet plug and socket system comprising:

- an outlet socket arranged at the outlet tube fitting of the outlet port, and

- an outlet plug, attached to the outlet end of the connection tube, the outlet plug being intended to be plugged into the outlet socket.

- The outlet tube is connected to one or both of a decay station for receiving the probes after their irradiation in the core of the nuclear reactor, in particular in the probe receiving fingers, and a probe supply unit.

- The nuclear reactor is a heavy water reactor, in particular a CANDU reactor.

The invention also relates to an installation for producing activated probes in the core of a heavy water nuclear reactor, in particular a CANDU reactor, comprising:

- a device for subjecting probes to irradiation in the core of a nuclear reactor as described above, extending into the core of the nuclear reactor and intended for receiving probes in view of their irradiation in the core of the nuclear reactor;

- a probe supply system, configured for supplying non-activated probes to the device for subjecting probes to irradiation in the core of a nuclear reactor,

- a decay station configured for receiving the probes irradiated in the core of the nuclear reactor from the device for subjecting probes to irradiation in the core of a nuclear reactor,

- a probe discharge system for discharging the probes from the installation, an inlet of the probe discharge system being connected to the decay station; and

- a probe drive system, configured for transporting the probes through the installation, the probe drive system being preferably a pneumatic system.

The invention also relates to an installation for producing activated probes in the core of a heavy water nuclear reactor, in particular a CANDU reactor, comprising:

- a device for subjecting probes to irradiation in the core of the nuclear reactor, extending into the core of the nuclear reactor and intended for receiving probes in view of their irradiation in the core of the nuclear reactor; - a probe supply system, configured for supplying non-activated probes to the device for subjecting probes to irradiation in the core of the nuclear reactor;

- a decay station configured for receiving the probes irradiated in the core of the nuclear reactor from the device for subjecting probes to irradiation in the core of a nuclear reactor,

- a probe discharge system for discharging the probes from the installation, an inlet of the probe discharge system being connected to the decay station;

- a diverter as described above, each inlet port of the diverter being connected to a probe receiving finger of the device for subjecting probes to irradiation in the core of the nuclear reactor and the outlet port of the diverter being connected to one or both of the decay station and the probe supply system; and

- a probe drive system, configured for transporting the probes through the installation, the probe drive system being preferably a pneumatic system.

According to a particular embodiments of the installation, the device for subjecting probes to irradiation in the core of the nuclear reactor is a device as described above.

The invention also relates to a heavy water reactor, comprising:

- a calandria housing a plurality of calandria tubes, each calandria tube containing a fuel element, a heavy water moderator flowing through the calandria;

- a reactivity mechanism deck, located above the calandria, and comprising at least one port, for example a view port, and

- an installation as described above.

According to particular embodiments of the heavy water reactor:

- The device for subjecting probes to irradiation in the core of the nuclear reactor is a device as described above, and the probe receiving fingers of the device for subjecting probes to irradiation in the core of the nuclear reactor extend vertically downwards into the calandria through the port of the reactivity mechanism deck.

- The heavy water reactor further comprises a guide tube, inserted into the port of the reactivity mechanism deck, the probe receiving fingers of the device being inserted into the guide tube and the head of the device bearing on a top surface of the guide tube.

- The heavy water reactor is a CANDU type reactor.

The invention will be better understood upon reading the following description, given only by way of example with reference to the appended drawings, in which:

- Figure 1 shows a typical CANDU reactor assembly;

- Figure 2 shows a partial cross-sectional side view of the heavy water reactor calandria shown in Figure 1 ; - Figure 3 shows a top view of the heavy water reactor shown in Figure 1 , showing view port locations, schematically illustrating the locations of reactivity control units in a reactivity mechanism deck positioned above the calandria;

- Figure 4 shows an end view of the heavy water reactor shown in Fig. 1 ;

- Figure 5 shows a reactivity mechanism deck of the heavy water reactor shown in Fig. 1 , showing the view port location;

- Figure 6 shows a side view of the heavy water reactor shown in Fig. 1 , showing the view port location with a device for subjecting probes to irradiation in the core of a nuclear reactor in accordance with an embodiment of the present invention in place;

- Figure 7 is a cross-sectional schematic view of the device according to the invention;

- Figure 8 is an enlarged view of the top part of Figure 7;

- Figure 9 is a schematic side view of a diverter according to another aspect of the invention;

- Figure 10 is a schematic side view of a diverter according to another aspect of the invention;

- Figure 1 1 is a schematic view of a detail of the diverter of figure 9; and

- Figure 12 is a schematic view of an installation for producing activated probes in the core of a nuclear reactor.

In the following description, the invention is described in the context of a CANDU heavy water reactor. However, the invention may also be used in any other type of heavy water reactor.

Fig. 1 shows a typical CANDU reactor assembly. The typical CANDU reactor assembly has separate pressure boundaries categorized as:

- the primary cooling loop where the fuel is contained,

- the moderator system, the function of the moderator being to slow the neutrons; and

- the end shield which provides radiation shielding and supports the primary cooling loop fuel channels.

The moderator system is a separate system, isolated from the primary cooling loop.

In the example shown in Figure 1 , the primary cooling loop components comprise fuel channel end fittings 10 and feeder pipes 1 1 . The moderator system components comprise the calandria 1 , calandria shell 2, calandria tubes 3, inlet-outlet strainer 8, moderator outlet 12, moderator inlet pipe 13, pipe to moderator expansion head tank 18, moderator discharge pipes 20, rupture disc 21 , calandria nozzles for reactivity control units 22 and calandria tubesheet 29. The end shield includes the endshield embedment ring 4, fuelling tubesheet 5, endshield lattice tube 6, endshield cooling pipes 7, and steel ball shielding 9. The ports that penetrate the moderator system include ports for horizontal flux detectors units and liquid injection units 14, ion chambers 15, view port 23, shutoff unit 24, adjustor unit 25, control absorber unit 26, liquid zone control unit 27 and vertical flux detector unit

28. The assembly is housed in a concrete reactor vault wall 17, with curtain shielding slabs 19, and the overall assembly is protected against seismic events with earthquake restraints 16.

The reactor core enclosure shown in Fig. 1 is in the form of a calandria 1 , which is delimited by a horizontal cylindrical shell 2. A plurality of calandria tubes 3 are housed inside of calandria shell 2. The heavy water moderator flows into and out of the volume inside calandria 1 via piping 12,13 delimited between the inner surface of calandria shell 2, the outer surfaces of calandria tubes 3 and calandria tubesheet 29. The primary coolant loop, which contains the fuel elements, is physically separate and flows from the feeder pipes 1 1 , through the fuel channel end fitting 10, and down the pressure tube (a.k.a. fuel channel containing the fuel element) and out the opposite fuel channel end fitting 10 and into the opposite feeder pipe 1 1 . As schematically shown in the partial cross- sectional view of Fig. 2, heavy water moderator is contained inside the volume delimited between the inner surface of calandria shell 2, the outer surfaces of calandria tubes 3 and calandria tubesheet

29. Each calandria tube 3 surrounds a pressure tube (a.k.a. fuel channel) 44 housing a plurality of fuel elements 51 therein. Calandria tubes 3, along with a gas filled annular space 48 maintained by garter spring spacers 46, provide a buffer between pressure tubes 44 and the moderator heavy water so heated heavy water primary coolant in pressure tubes 44 does not boil the heavy water moderator. Primary coolant flows into pressure tubes 44 from a cold leg of a primary coolant loop from a feeder pipe 1 1 into an end fitting 10 and flows to receive heat from fuel elements 51 , then flows out of pressures tubes 44 at the opposite end fitting 10 and out a feeder pipe 1 1 to a hot leg of the primary coolant loop for flowing through a steam generator located downstream in the hot leg. Closure plugs 52 are on each end fitting 10 to allow for on-line fueling.

Figure 1 further shows moderator inlet pipes 13 for providing cooled water from a moderator main circuit, moderator outlet pipes 12 for providing heated moderator water back to moderator main circuit for cooling and pressure discharge pipes 20 for relieving pressure inside calandria shell 2. A plurality of horizontally extending neutron flux detector units 14 extend horizontally through calandria 1 to monitor the neutron flux in calandria 1 during the operation of reactor. Extending vertically through core are a plurality of reactivity control units therein.

Figure 3 shows a top plan view schematically illustrating the locations of reactivity control units in a reactivity mechanism deck 45 positioned above the calandria 1 . Reactivity mechanism deck holds all the reactivity control units that extend below reactivity mechanism deck and penetrate calandria 1 from above. From Figure 1 , the reactivity control units include vertically extending neutron flux detector units 28, liquid zone control units 27, adjuster units 25, control absorber units 26 and reactor shutoff units 24, which are all need to be available and capable of operating during the operation. In addition to the reactivity control units, reactivity mechanism deck 45 also includes two view ports 23 extending therethrough. A first view port 49, i.e., a high flux inspection port, is aligned with a high flux region of the reactor core and a second view port 50, i.e., a low flux inspection port, is aligned with a low flux region of the reactor core. View ports 49, 50 are used during the periodic inspection to monitor corrosion and wear of the reactor at two regions exposed to different levels of neutron flux.

Figure 4 shows a cross-sectional side view, which illustrates the positioning of reactivity mechanism deck 45 above calandria 1 with the view port 23 location. An existing thimble 53 is in place in the view port to allow insertion of a guide tube to monitor neutron flux during the initial startup of reactor when brand new fuel is provided into the reactor. An aluminum guide tube is typically provided with barium fluoride detectors having a very high sensitivity to neutron flux. Once the reactor is started up and neutron flux is detected by the barium fluoride detector, the aluminum guide tube is removed. Leaving the aluminum guide tube during normal operation would lead to permanent damage. After initial startup, view ports are available to have radioisotope production guide tubes inserted.

Figure 5 shows the reactivity mechanism deck 45 with the view port 23 location as well as relative location with respect to, shut off unit 24, adjustor unit 25, control absorber unit 26, liquid zone control unit 27 and vertical flux detector units 28.

The device 55 for subjecting probes to irradiation in the core of the nuclear reactor according to the invention is intended to be inserted into a port of the reactivity mechanism deck 45 of the nuclear reactor, more particularly into a spare port of the reactivity mechanism deck 45. The device 55 is advantageously intended to be inserted into the view port 23 of the reactivity mechanism deck 45.

As shown in Figure 6, the device 55 is preferably inserted into a guide tube 56, which is itself inserted into the port of the reactivity mechanism deck 45, in particular the view port 23. The guide tube 56 extends into the calandria 1 of the heavy water reactor, and therefore into the heavy water moderator. The guide tube 56 is preferably filled with helium. In this embodiment, the device 55 is therefore not directly in contact with the heavy water moderator contained in the calandria 1 .

According to an alternative, the device 55 is inserted into the port of the reactivity mechanism deck, in particular the view port 23, and is in direct contact with the heavy water moderator contained in the calandria 1 . This embodiment has, however, a lower stability than the embodiment in which the device 55 is inserted into a guide tube 56 described above.

The device 55 will now be described in detail with reference to Figures 6, 7 and 8.

The device 55 comprises:

- a plurality of probe receiving fingers 60;

- a head 62, to which the probe receiving fingers 60 are attached; and

- a pneumatic transport system 64, configured for transporting the probes into and out of the probe receiving fingers 60.

Each probe receiving finger 60 is configured for receiving a plurality of probes in view of their irradiation in the core of the nuclear reactor.

The probes for example have a cylindrical or a spherical shape. In the case of a spherical probe, the diameter of the probe is preferably lower than or equal to 12 mm. In the case of a cylindrical probe, the diameter of the probe is lower than or equal to 12 mm, and the height of the probe is lower than or equal to 100 mm.

The probe is preferably an irradiation target.

The irradiation target comprises an envelope encapsulating a core made of non-fissile material and comprising a suitable precursor material for generating radionuclides, which are to be used for medical and/or other purposes. More preferably, the precursor material converts to a desired radionuclide upon activating by exposure to neutron flux present in the reactor core. Useful precursor materials are Mo-98 and Yb-176, which are converted to Mo-99 and Lu-177, respectively. It is understood, however, that the invention is not limited to the use of a specific precursor material.

The envelope encapsulates the core in a hermetic manner. It is for example made of a metallic material. The core in particular comprises the precursor material in powder form.

According to an alternative, the probe is a neutron flux measurement probe, which is used for measuring the neutron flux in the core.

Each probe receiving finger 60 defines a longitudinal axis L. When the device 55 is inserted into the corresponding port of the reactivity mechanism deck 45, each probe receiving finger 60 extends vertically downwards into the core of the nuclear reactor, and more particularly into the calandria 1 of the nuclear reactor, the longitudinal axis L thus extending vertically downwards.

In the following description, the terms lower, upper, bottom and top are used with respect to the normal orientation of the device 55 in the use configuration, i.e. when inserted into the corresponding port of the reactivity mechanism deck 45. The number of probe receiving fingers 60 is preferably greater than or equal to two, for example greater than or equal to three, and more particularly equal to six. The probe receiving fingers 60 are for example arranged on the head 62 in a circle.

Each probe receiving finger 60 has a double walled structure comprising an inner tube 68 and an outer tube 70, defining an annular space 72 there-between. The annular space 72 is intended for receiving a circulation of pressurized gas from a pressurized gas supply system of the pneumatic transport system 64.

The inner tube 68 and the outer tube 70 extend coaxially and are centered on the longitudinal axis L of the probe receiving finger 60. The inner tube 68 delimits an inner passage 69 for the circulation of the probes. The inner tube 68 is intended for receiving the probes in view of their irradiation in the core of the nuclear reactor.

The inner tube 68 and the outer tube 70 are preferably made of a metallic material, and for example of zirconium or stainless steel.

As shown in Figure 7, the outer tube 70 is closed at its bottom end 76. The bottom end 76 for example has a conical shape. However, other shapes may also be used for the bottom end 76.

The inner tube 68 has a bottom end 78 which extends at a distance, taken along the longitudinal direction L, of the bottom end 76 of the outer tube 70, and more particularly at a distance above the bottom end 76, such that the annular space 72 communicates, at a bottom end 79 of the probe receiving finger 60, with the inner passage 69 of the inner tube 68. Therefore, pressurized gas flowing downwards through the annular space 72 is able to enter the inner tube 68 at the bottom end 78 thereof, and then to flow upwards through the inner passage 69 of the inner tube 68, pushing probes contained in the inner tube 68 upwards and out of the probe receiving finger 60.

The device 55 further comprises, for each probe receiving finger 60, a connection port 80 for connection of the probe receiving finger 60 to a tube of a probe handling system for transporting the probes into and/or out of the probe receiving finger 60.

The connection port 80 is located at an upper end 82 of the probe receiving finger 60.

More particularly, the probe receiving finger 60 is intended to be connected, through the connector 80, to a decay station of a probe handling system and/or to a probe supply system configured for supplying non-activated probes to the device 55 for subjecting probes to irradiation in the core of a nuclear reactor.

The connection port 80 forms a pressure-tight connection with the probe receiving finger 60. More particularly, the connection port 80 is screwed into the upper end 82 of the probe receiving finger 60 in a pressure-tight manner. The connection port 80 is further configured for connection to a tube of a probe handling system in a pressure-tight manner, for example by screwing to a corresponding connector of the tube of the probe handling system.

In the context of this invention, “pressure-tight” is in particular used with reference to the pressure prevailing in the guide tube 56 in case the guide tube 56 is damaged. This pressure is in particular defined based on the same design criteria as for the containment penetration valves. In other words, a “pressure-tight” connection or part is in particular capable of withstanding the pressure existing in the guide tube 56 in case the guide tube 56 is damaged, in order to avoid leakage through these connections or parts.

In the example shown in Figures 7 and 8, the inner tube 68 extends through a through- hole delimited in the head 62. The upper end 86 of the inner tube 68 is located above the head 62.

The inner tube 68 is connected to the head 62, preferably by screwing. In particular, the inner tube 68 comprises a cylindrical lateral wall 87 outwardly delimiting the inner passage 69 of the inner tube 68 and a radial annular flange 88 which extends outwardly from the lateral wall 87 and bears on an upper surface 1 10 of the head 62. As shown in Figure 8, this radial annular flange 88 is screwed to the head 62 by means of one or more screws 89.

Preferably, the probe receiving finger 60 further comprises a sleeve 90 extending between the upper end 86 of the inner tube 68 and the connection port 80. The sleeve 90 has a tubular shape. It extends coaxially to the inner tube 68, and delimits an inner passage 91 for the passage of the probes.

An upper section 94 of the sleeve 90 comprises a seat 96 for the connection port 80. More particularly, the upper section 94 of the sleeve 90 forms the upper end 82 of the probe receiving finger 60. The connection port 80 is in particular screwed into the seat 96 in a pressure-tight manner.

A lower end 92 of the sleeve 90 is connected to the upper end 86 of the inner tube 68, and more particularly fitted over the upper end 86 of the inner tube 68. In the example shown in the figures, the sleeve 90 has an interior wall comprising a shoulder 93, which bears on an upper annular surface 97 of the inner tube 68. The portion of the sleeve 90 located below this shoulder 93 extends over the inner tube 68. The portion of the sleeve 90 located below the shoulder 93 has an inner diameter which is greater than the inner diameter of the portion of the sleeve 90 located above the shoulder 93 by the wall thickness of the inner tube 68.

More particularly, the sleeve 90 comprises a central cylindrical section 100, a radial annular flange 102 at the lower end of the cylindrical section 100 forming the lower end of the sleeve 90 and the upper section 94 comprising the seat 96 at the upper end of the cylindrical section 100 and forming an upper end of the sleeve 90. The radial annular flange 102 bears on the upper surface 110 of the head 62. In the example shown in Figures 7 and 8, the radial annular flange 102 bears on the upper surface 110 indirectly through the radial annular flange 88 of the inner tube 68. The diameters of the radial annular flange 102 and of the radial annular flange 88 are in particular substantially equal.

The sleeve 90 is connected to the head 62, in particular through screwing.

In the example shown in Figures 7 and 8, the radial annular flange 102 bears on the upper surface 1 10 indirectly through the radial annular flange 88 of the inner tube 68 and screws 89 are inserted through corresponding through holes formed in the superimposed radial annular flanges 88 and 102 and then screwed into a threaded hole formed in the head 62, thus attaching both the inner tube 68 and the sleeve 90 to the head 62.

The radial annular flange 102 has an outer diameter which is greater than that of the central cylindrical section 100. It therefore extends outwards compared to the central cylindrical section 100.

In the example shown in the Figures, a recess 1 12 is formed in the upper surface 110 of the head 62, the recess 1 12 receiving the radial annular flanges 88 and 102. The diameter of the recess 112 is for example substantially equal to the diameter of the radial annular flanges 88 and 102.

The seat section 104 has an outer diameter which is greater than that of the central cylindrical section 100. In the example shown in the Figures, the outer diameter of the seat section 104 is the same as the outer diameter of the radial annular flange 102.

The probe receiving finger 60 delimits a cylindrical interior passage for the passage of the probes. This cylindrical interior passage extends downwards from the upper end 82 of the probe receiving finger 60. In the example shown in Figures 7 and 8, the cylindrical interior passage is successively delimited, from the top to the bottom of the probe receiving finger 60, by the sleeve 90 and the inner tube 68 of the probe receiving finger 60. The inner passage 91 of the sleeve 90 has substantially the same diameter as the inner passage 69 of the inner tube 68. Therefore, the inner wall of the cylindrical interior passage of the probe receiving finger 60 has a smooth surface at the junction between the sleeve 90 and the inner tube 68, thus facilitating the passage of the probes through the cylindrical interior passage.

At the bottom end of the cylindrical interior passage, the probe receiving finger 60 includes a probe stop, which is configured for stopping the probes from moving further downwards. The probe stop is in particular formed in the bottom end 76 of the outer tube 70. In the example shown in the Figures, the head 62 comprises a body 80 comprising an upper part 81 and a lower part 83, connected to each other. The upper and lower parts 81 , 83 are preferably connected by screws (not shown). However, they may also be connected through other adapted connection means. The body 80 for example has a substantially cylindrical outer contour.

The outer tube 70 is clamped to the head 62 at its top end 74. More particularly, the outer tube 70 comprises a cylindrical lateral wall 75 outwardly delimiting the annular space 72 between the inner tube 68 and the outer tube 70 and a radial annular flange 77, located at the top end 74 of the outer tube 70, the radial annular flange 77 extending radially outwards from the cylindrical lateral wall 75. As shown in Figure 8, the radial annular flange 77 is clamped between the upper and lower parts 81 , 83 of the body 80 of the head 62.

The fact that the outer tube 70 is clamped to the body 80 of the head 62 rather than being screwed thereto individually is advantageous, since it makes it possible to arrange the probe receiving fingers 60 closer to each other, and therefore improves the compactness of the device 55.

The body 80 defines, for each probe receiving finger 60, a gas conduit 113 for receiving a flow of pressurized gas from the pneumatic transport system 64. In addition, the device 55 comprises a gas supply port 1 19 for connection to a pressurized gas supply line 120 of the pneumatic transport system 64 for supply of pressurized gas.

More particularly, the gas conduit 113 is formed by a bore formed in the body 80. In the example shown in Figures 7 and 8, the gas conduits 113 are formed in the upper part 81 of the head 62. Each gas conduit 113 has a first end 115 opening into the annular space 72 between the inner tube 68 and the outer tube 70 of the respective probe receiving finger 60 and a second end 1 17 connected to the gas supply port 119.

The gas conduits 1 13 of the different probe receiving fingers 60 are separated from each other fluidically.

The gas supply port 1 19 is connected to the conduit gas 113 in a pressure-tight manner. More particularly, it is screwed to the body 80 in a pressure-tight manner. Each gas supply port 119 is connected to its own pressurized gas supply line 120.

The conduit 113, the annular space 72, the inner tube 68 and the outer tube 70 are configured in such a manner that pressurized gas supplied at the gas supply port 119 of a considered probe receiving finger 60 flows through the conduit 113 into the annular space 72, and then flows down the annular space 72 until reaching the bottom of the probe receiving finger 60, and then flows upwards through the inner passage 69 of the inner tube 68 so as to push the probes upwards out of the inner tube 68. In the example shown in Figures 7 and 8, each gas conduit 1 13 comprises a first conduit portion 121 extending perpendicular to the longitudinal axis L of the respective probe receiving finger 60 from the first end 115 of the conduit 1 13 and a second conduit portion 123 extending upwards and perpendicular to the first conduit portion 121. The second conduit portion 123 comprises a first end opening into the first conduit portion 121 and a second end forming the second end 1 17 of the conduit 113, and connected to the gas supply port 1 19. In this example, the first conduit portion 121 comprises, at the junction with the second conduit portion 123, a cylindrical conduit section and, at its first end, an annular chamber 127 extending around the inner tube 68, above the annular space 72 and communicating fluidically with the annular space 72. In the example shown on the Figures, the first conduit portion 115 opens out through a lateral opening 129 into a lateral surface 130 of the body 80 due to manufacturing constraints. This lateral opening 129 is closed in a pressure-tight manner using an adapted plug 131 , which is, for example, screwed into the first conduit portion 1 15 in a pressure-tight manner.

According to an alternative (not shown in the drawings), the gas conduit 1 13 only comprises the first conduit portion 115 and the gas supply port 1 19 is connected to the lateral opening 131 of the first conduit portion 115. This alternative can, however, only be used if there is sufficient space for a connection of a pressurized gas supply line 120 on the side of the body 80.

The device 55 further comprises first seals 140 for pressure-tight sealing of the inner passage 69 of each inner tube 68. The first seals 140 are in particular inserted between the radial annular flange 88 of each inner tube 68 and the radial annular flange 102 of the sleeve 90. They are in particular formed by annular rings inserted into a corresponding recess of the radial annular flange 88 or of the radial annular flange 102. The first seals 140 prevent fluid from outside the probe receiving finger 60, in particular the helium contained in the guide tube 56 or the moderator in the case where there is no guide tube, from entering the inner passage 69 of the inner tube 68.

The device 55 further comprises second seals 145 for pressure-tight sealing of the annular space 72 between the inner tube 68 and the outer tube 70. The second seals 145 are in particular inserted between the radial annular flange 88 of each inner tube 68 and the upper part 81 of the body 80 and/or between the radial annular flange 77 of each outer tube 70 and the upper part 83 of the body. They are in particular formed by annular rings inserted into corresponding recesses of the upper part 81 of the body 80, respectively the lower body portion or of the radial annular flange 88 or of the radial annular flange 77. The second seals 145 ensure that the different probe receiving fingers 60 are independent of each other, by preventing a fluidic communication between the fingers 60 through the space between the upper and the lower parts 81 , 83 of the body 80.

In the embodiment shown in the Figures, the device 55 also comprises third seals 148 for preventing the helium present in the guide tube 56 from escaping from the guide tube 56 through the device 55. These third seals 148 are located between the bottom of the radial annular flange 77 of the outer tube 80 and the lower part 83 of the body 80.

The device 55 is constructed in a pressure-tight manner.

The device 55 is further constructed in such a manner that the flow of gas through each probe receiving finger 60 can be controlled independently.

The pneumatic transport system 64 is configured for supplying a flow of pressurized gas through the inner tube 68 in a first direction for pushing the probes into the probe receiving finger 60 and in a second direction, opposite the first direction, for pushing the probes out of the probe receiving finger 60.

More particularly, for introducing the probes into the probe receiving finger 60, the pneumatic transport system 64 is configured for activating a flow of gas which enters the probe receiving finger 60 at the connection port 80 and flows downwards through the inner tube 68, thus pushing the probes into the probe receiving finger 60. The device 55 is further configured such that the pressurized gas introduced into the inner passage 69 of the inner tube 68 then flows from the bottom end 78 of the inner tube 68 into the annular space 72, and then flows upwards through the annular space 72 and through the gas conduit 82 and is then evacuated through the gas supply port 1 19.

For discharging the probes from the probe receiving finger 60 after their irradiation in the core of the nuclear reactor, the pneumatic transport system 64 is configured for activating, for each probe receiving finger 60, a flow of gas through the pressurized gas supply line 120 of the considered probe receiving finger 60, through the gas supply port 119, through the gas conduit 113 and into the annular space 72, then down to the bottom of the annular space 72 and up the inner passage 69 of the inner tube 68 so as to push the probes contained in the probe receiving finger 60 upwards. The pressurized gas is then evacuated through the connector 80 located at the upper end 82 of the probe receiving finger 60 together with the probes.

As described previously, the pneumatic transport system 64 comprises one pressurized gas supply line 120 for each gas supply port 1 19, each pressurized gas supply line 120 being connected to a corresponding gas supply port 1 19. The pressurized gas supply lines are connected to a common gas supply source. Each pressurized gas supply line 120 comprises a valve configured for selectively opening or closing the pressurized gas supply line 120 such that the supply of pressurized gas to each probe receiving finger 60 may be controlled independently by the pneumatic transport system 64. Therefore, the pneumatic transport system 64 is further configured for controlling pressurized gas supply to each probe receiving finger 60 independently. The probes contained in the probe receiving fingers 60 may therefore be discharged from each probe receiving finger 60 independently of the other probe receiving fingers 60.

The device 55 further comprises a lifting handle 150 for lifting the device 55 as a whole, for example for lifting the device 55 out of the port 23 of the reactivity mechanism deck 45. The lifting handle 150 is for example formed by an annulus attached to the body 80, and more particularly on the upper surface 110 of the upper part 81 of the body 80.

The device 55 according to the invention is advantageous. Indeed, since the probe receiving fingers 60 are isolated from each other from a fluidic point of view, and since the supply of pressurized gas to each probe receiving finger 60 may further be controlled independently for each probe receiving finger 60 through the corresponding connector 80 or gas supply port 1 19, it is possible to insert and remove probes from the different probe receiving fingers 60 independently. This allows producing different types of isotopes, with different activation times, or producing the same isotopes sequentially in time in the different probe receiving fingers 60, such that there are always activated isotopes available. The device 55 therefore results in an improved flexibility with respect to the manufacturing of activated isotopes.

In addition, the design of the device 55 is particularly compact and robust. It is therefore particularly adapted for being used in the core of a heavy water reactor, in particular a CANDU reactor, as described above, where the space available is relatively small. In particular, since the device 55 may for example include six tubes, a relatively high number of probes may be irradiated simultaneously, thus resulting in an improved productivity.

Furthermore, the device 55 according to the invention allows the insertion of much larger probes than was possible with prior art installations, and in particular of cylindrical probes having a diameter up to 12 mm. Therefore, this device 55 results in an improved productivity, since a greater amount of isotopes may be produced in the device within a given time.

The fact that both spherical and cylindrical probes may be used also increases the flexibility of use of the device 55.

The compact and stiff design of the device 55 is also advantageous compared to prior art devices, as it results in an increased resistance to earthquakes.

According to another aspect, the invention also relates to a diverter 200 for selectively connecting one of a plurality of inlet tubes 208 to one single outlet tube 216. Each inlet tube 208 is intended to be connected to a respective probe receiving finger intended for receiving probes for their irradiation in the core of the nuclear reactor.

The outlet tube 216 is intended to be connected to a probe handling system, and for example to one or both of a decay station for receiving the probes after their irradiation in the probe receiving fingers and a probe supply system for supplying non-activated probes.

The decay station is intended for temporary storage of the probes which were discharged from the probe receiving fingers after irradiation in the core of the nuclear reactor, so as to allow for a decay of the activity of these probes, prior to their transfer to a discharge system.

In the present patent application, the terms “inlet” and “outlet” are used with respect to a situation in which the probes circulate from the inlet tube 208 to the outlet tube 216. This situation corresponds to the discharge of activated probes from the core of the nuclear reactor. Of course, the diverter 200 may also be used in a situation in which the probes circulate from the outlet tube 216 to the inlet tube 208, for example when non-activated probes are transported from the probe supply system connected to the outlet tube 216 into the core of the nuclear reactor. The direction of displacement of the probes through the diverter is in particular determined by the direction of flow of the pressurized gas.

The diverter 200 is located outside of the core of the nuclear reactor.

The diverter 200 will now be described in detail with reference to Figures 9 to 11 .

The diverter 200 comprises n inlet ports 202, n being an integer greater than or equal to three. The number of inlet ports 202 is for example equal to 6.

This diverter 200 is in particular adapted for being connected, on its inlet side, to the device 55 for subjecting probes to irradiation in the core of the nuclear reactor described above with reference to Figures 6 to 8. In this case, the diverter 200 has as many inlet ports 202 as there are probe receiving fingers 60 in the device 55 for subjecting probes to irradiation in the core of the nuclear reactor.

Each inlet port 202 comprises an inlet tube fitting 204. The inlet tube fitting 204 comprises an inlet end 206 connected to an inlet tube 208. For example, for each inlet port 202, the inlet tube 208 is a tube having an inlet end connected to one of the probe receiving fingers 60, and in particular to the connecting port 80 of one of the probe receiving fingers 60.

As can be seen in Figure 10, the inlet ports 202 are arranged on at least a portion of a circle, the circle defining a circle plane P. In the example shown in Figure 10, the inlet ports 202 are arranged on a circle, the circle defining the circle plane P. However, the inlet ports 202 may, according to an alternative, be arranged only on a portion of a circle, the circle defining the circle plane P. According to one example, the angular spacing between adjacent inlet ports 202 is regular. It is for example identical between any pair of adjacent inlet ports 202. For example, in the example shown in Figure 10, in which the diverter 200 comprises exactly six inlet ports 202, the inlet ports 202 form a circle with an angular spacing equal to about 360/6 degrees between adjacent inlet ports 202.

According to an alternative, the angular spacing between adjacent inlet ports 202 is not regular or the angular spacing between adjacent inlet ports 202 is not identical between all pairs of adjacent inlet ports 202. For example, the angular spacing between adjacent inlets ports 202 is identical, except for the two inlet ports 202 located at the ends of the circle portion.

In the example shown in Figures 9 to 11 , the inlet ports 202 are fixed to an inlet support structure 210. The inlet support structure 210 extends in the circle plane P. The inlet support structure 210 is fixed in position, which means that it is not movable. The inlet support structure 210 is for example plate-shaped.

The diverter 200 further comprises one single outlet port 211 , comprising an outlet tube fitting 212. The outlet tube fitting 212 comprises an outlet end 214 configured to be connected to an outlet tube 216.

The outlet tube fitting 212 is arranged in the alignment of the center C of the circle, taken along a longitudinal direction A of the diverter 200. The longitudinal direction A is a direction extending perpendicular to the plane P of the circle. The outlet tube fitting 212 has been drawn schematically in broken lines on Figure 10, the broken lines indicating that the outlet tube fitting 212 is located in a plane parallel to the plane of Figure 10, the plane of Figure 10 being the plane P of the circle.

In the example shown in Figure 9, the outlet tube fitting 212 is fixed to an outlet support structure 218. The outlet support structure 218 is for example plate-shaped.

The outlet support structure 218 is displaceable in translation along the longitudinal direction A of the diverter 200. The direction of displacement is shown by arrow “D” in Figure 9. Translation of the outlet support structure 218 along the longitudinal direction A moves the outlet support structure 218 and therefore also the outlet tube fitting 212, and changes the distance between the outlet tube fitting 212 and the inlet tube fittings 204. Preferably, the outlet support structure 218 is movable in translation along the longitudinal direction A between two positions, in which it may be fixed, a first end position corresponding to the use position of the diverter 200, shown in Figure 9, and a second end position in which the outlet support structure 218 is spaced further away from the inlet support structure 210 than in the first position. The diverter 200 further comprises a connection tube 220 comprising an inlet end 222, connected to an outlet end 224 of one of the n inlet tube fittings 204 and an outlet end 226, connected to an inlet end 228 of the outlet tube fitting 212, thus forming a path for the circulation of the probes from this inlet port 202 to the outlet port 212, and therefore between the inlet tube 208 connected to the inlet port 202 and the outlet tube 216 connected to the outlet port 212.

In the example shown in Figure 9, the connection tube 220 has a curved shape and comprises two substantially straight end sections and a curved intermediate section inbetween. The transition between the curved intermediate section and each of the substantially straight end sections is continuous, i.e. without angles. In the example shown in Figure 9, the intermediate section bends continuously between its two ends. More particularly, the intermediate section includes a concave section and a convex section separated by an inflexion point. In particular, the inflexion point is located in the geometric middle of the central axis of the intermediate section, measured along the central axis of the intermediate section. This continuous bending and the absence of angles along its length allows for a particular smooth displacement of the probes through the connection tube, despite the changes of direction.

The inlet end 206 of each inlet tube fitting 204 is configured for forming a pressure- tight connection with a respective inlet tube 208. The outlet end 224 of each inlet tube fitting 204 is configured for forming a pressure-tight connection with the inlet end 222 of the connection tube 220. For example, the inlet end 206 and the outlet end 224 of the inlet tube fitting 204 form pressure-tight screw connections respectively with the inlet tube 208 and with the inlet end 222 of the connection tube 220.

Optionally, the inlet end 228 of the outlet tube fitting 212 is configured for forming a pressure-tight connection with the outlet end 224 of the connection tube 220, and the outlet end 214 of the outlet tube fitting 212 is configured for forming a pressure-tight connection with the outlet tube 216. For example, the inlet end 228 and the outlet end 214 of the outlet tube fitting 212 and the inlet end 206 and the outlet end 224 of the inlet tube fitting 204 respectively form pressure-tight screw connections with the outlet end 224 of the connection tube 220 and with the outlet tube 216.

The inlet port 202 corresponding to the inlet tube fitting 204 to which the connection tube 220 is connected is an active inlet port and the remaining n-1 inlet ports are inactive inlet ports.

In this context, “active” means that this inlet port 202 is the one through which the probes travel into the connection tube 220, while no probes circulate through the “inactive” inlet ports 202. In the example shown in Figure 9, the active inlet port is the top inlet port 202, while the remaining five inlet ports 202 are inactive. As will be explained later, the active inlet port 202 may be varied by displacing the connection tube 220.

The diverter 200 further comprises a plurality of closure plugs 230, schematically represented in Figure 9.

When the connection tube 220 is connected to the active inlet port 202 and to the outlet port 21 1 , closure plugs 230 are inserted into the outlet ends 224 of the inlet tube fittings 204 of the inactive inlet ports 202. The closure plugs 230 are configured to close these inlet tube fittings 204 in a pressure-tight manner. The closure plugs 230 are in particular formed by screw caps, which are adapted for being screwed into the outlet ends 224 in a pressure-tight manner.

When the connection tube 220 is not connected between an inlet port 202 and the outlet port 21 1 , for example during activation of the probes in the core of the nuclear reactor, closure plugs 230 as described above are inserted into the outlet ends 224 of all the inlet tube fittings 204 and optionally into the inlet end 228 of the outlet tube fitting 212.

The connection tube 220 is displaceable between n positions, each position corresponding to the connection of the inlet end 222 of the connection tube 220 to the outlet end 224 of one of the n inlet tube fittings 204 and of the outlet end 226 of the connection tube 220 to the inlet end 228 of the outlet tube fitting 212. In each position of the connection tube 220, the inlet port 202 to which the connection tube 220 is connected is the active inlet port and the remaining inlet ports 202 are inactive inlet ports. In the example shown in Figures 9 to 1 1 , the connection tube 220 is therefore displaceable between six different positions. In each of the n positions of the connection tube 220, the diverter creates a pathway from one particular inlet tube 208 to the outlet tube 216.

In the case where each of the inlet tubes 208 is connected to a corresponding probe receiving finger 60 of the device 55 described above and the outlet tube 216 to a decay station and/or to a probe supply system, depending on the position of the connection tube 220, and in particular on the inlet port 202 forming the active inlet port, the connection tube 220 allows for the circulation of the probes from the probe receiving finger 60 connected to the active inlet port 202 of the diverter 200 into the decay station or from the probe supply system to the probe receiving finger 60 connected to the active inlet port 202.

The connection tube 202 is configured to be manually displaceable between the n positions through the following sequential steps:

- displacement of the outlet support structure 218 in the longitudinal direction A of the diverter 200, i.e. along arrow D, so as to increase the distance between the inlet tube fitting 204 and the outlet tube fitting 212, i.e. to the right in Figure 9, - removal of the connection tube 202 from the inlet tube fitting 204 and the outlet tube fitting 212,

- positioning of the inlet end 222 and the outlet end 226 of the connection tube 202 in a position respectively facing the inlet tube fitting 204 of the inlet port 202 which is to be the active inlet port 202 and the outlet tube fitting 212; and

- pressure-tight connection of the inlet and outlet ends 222, 226 of the connection tube 220 to the inlet tube fitting 204 and the outlet tube fitting 212 in front of which they are positioned so as to establish a path between this inlet tube fitting 204 and the outlet tube fitting 212.

These steps are carried out by an operator.

The removal step in particular includes a sub-step of displacing the outlet support structure 218 in translation along the longitudinal direction A of the diverter from its first position into its second position.

The connection tube 220 cannot be rotated relative to the inlet support structure 210 and the outlet support structure 218 without prior removal of the connection tube 220 from the inlet tube fitting 204 and the outlet tube fitting 212.

In the first position of the outlet support structure 218, the distance between the inlet support structure 210 and the outlet support structure 218 is such that the connecting tube 220 is connected to one inlet tube fitting 204 on its inlet end 222 and to the outlet tube fitting 212 on its outlet end 226, which means that the distance between the inlet support structure 210 and the outlet support structure 218 is substantially equal to the distance between the inlet end 222 and the outlet end 226 of the connecting tube 220. In the second position of the outlet support structure 218, the distance between the inlet support structure 210 and the outlet support structure 218 is greater than in the first position, and therefore allows disconnecting the inlet end 222 and the outlet end 226 of the connection tube 220 from the inlet tube fitting 204 and the outlet tube fitting 212.

The positioning step is in particular carried out by rotating the connection tube 202 about an axis of rotation parallel to the longitudinal direction D and passing through the center C of the circle.

The connection step preferably includes a sub-step of displacing the outlet support structure 218 in translation along the longitudinal direction A of the diverter from its second position into its first position.

The diverter 200 further comprises a detector 240 configured to detect which one of the inlet ports 202 is the active inlet port. The detector 240 comprises an inlet plug and socket system 242, shown more particularly in Figure 11 , and comprising: - an inlet socket 244 for each inlet port 202, the inlet socket 244 being arranged at the inlet tube fitting 204 of the inlet port 202, and

- an inlet plug 246, attached to the inlet end 222 of the connection tube 220.

The inlet plug and socket system 242 is configured in such a manner that the plug 246 can only be plugged into the socket 244 associated with the inlet port 202 to which the inlet end 222 of the connection tube 220 is connected. For example, the inlet plug 246 is attached to the connection tube 220 through a flexible connection link 250, the length of the flexible connection link 250 being chosen in such a manner that the plug 246 can only be plugged into the socket 244 associated with the inlet port 202 to which the inlet end 222 of the connection tube 220 is connected. The flexible connection link 250 is for example a chain or a cord.

More particularly, each inlet socket 244 is fixed to the inlet support structure 210 close to the corresponding inlet tube fitting 204, and for example at a distance chosen depending on the distance between adjacent or opposite inlet tube fittings 204.

In the example shown in Figure 10, the inlet socket 244 is for example aligned with the corresponding inlet tube fitting 204 along a radius of the circle. In this example, the inlet socket 244 is located closer to the center C of the circle than the corresponding inlet tube fitting 204. However, other geometries could also be used.

The detector 240 is configured in such a manner that, when the inlet plug 246 is plugged into one of the inlet sockets 244, a signal indicative of the fact that the corresponding inlet port 202 is the active inlet port 202 is generated. In particular, the detector 240 is configured in such a manner that, for each pair of plug 246 and socket 244, the plugging of the plug 246 into the socket 244 closes an electric circuit, the closing of the electric circuit resulting in the generation of the signal indicative of the fact that the corresponding inlet port 202 is the active inlet port. More particularly, the pins of the plug 246 are short-circuited, such that the insertion of the plug 246 into the socket 244 closes an electrical circuit between the plug 246 and the socket 244 which is detected by the detector 240 and triggers the emission of a corresponding signal.

In the embodiment shown in Figure 1 1 , the electrical circuitry inside the inlet socket 244 includes a two-wire cable 247 arriving at the inlet socket 244 and a resistor 248 connected between the two wires of the cable 247. The two-wire cable 247 is further connected to a control unit of the nuclear reactor. In this embodiment, the detector 240 is configured for measuring the resistance between the two wires of the cable 247 to determine whether a given inlet port 202 is active or not. If the inlet plug 246 is plugged into a given inlet socket 244, the resistance measured between the two wires of the cable 247 is substantially zero due to the short-circuit generated by the inlet plug 246. If the inlet plug 246 is not plugged into the inlet socket 244, the resistance between the two wires of the cable 247 is equal to the resistance of the resistor 248.

The detector 240 is further configured for detecting a breakage of the two wires of the cable 247 arriving to the inlet sockets 244. Indeed, in case one of the two wires of the cable is broken, an infinite resistance is measured between the lines 247.

According to one embodiment, the diverter 200 may include an outlet plug and socket system located at the outlet side of the diverter 200, and comprising:

- an outlet socket arranged at the outlet tube fitting 212 of the outlet port 211 , and

- an outlet plug, attached to the outlet end 226 of the connection tube 220, the outlet plug being intended to be plugged into the outlet socket.

This plug and socket system is analogous to the plug and socket system 242 described above, and will therefore not be described in detail.

The diverter 200 according to the invention is advantageous. Indeed, it allows connecting more than three, and in particular six, inlet tubes 208, for example each connected to a respective probe receiving finger 260, to a probe handling system, and in particular a decay station, in a compact and pressure-tight manner. More particularly, the diverter 200 allows increasing the irradiation capacities due to the fact that several probe receiving fingers, and for example six probe receiving fingers, located in the core of the nuclear reactor may be used without having to increase the number of system components for handling the probes located outside of the core of the nuclear reactor. This is particularly advantageous in the case of a heavy water reactor, such as the CANDU reactor. Indeed, when the probes are removed from the core, they are highly radioactive, and need to spend some time in a decay station, prior to being discharged from the nuclear reactor through a discharge system and to being transported to the client. Due to the fact that only little space is available in the CANDU reactor for the irradiation probe activation system, in the case where several fingers 60 are used for the activation of probes in the core, it is not possible to provide dedicated decay and discharge systems for each probe receiving finger 60. The above-described diverter 200 overcomes this issue by allowing to selectively connect one of the n probe receiving fingers 60 to one single decay station and discharge system depending on the needs. It therefore provides a compact solution for handling the activated probes.

Due to the pressure-tight implementation of the tube connections of the diverter 200, the diverter 200 also has the advantage of integrating the diverter 200 in the containment, which allows renouncing to certain containment penetration valves. Indeed, normally, containment penetration valves are located at the containment boundary to prevent primary fluid from exiting the containment in case of a leakage. In the present case, since all the connections of the diverter 200 are pressure-tight, there is no risk of primary fluid exiting the containment at the diverter 200.

Providing pressure-tight closure caps 230 for the ends of the fittings 204, 212 which are not being used also contributes to the pressure-tightness of the diverter 200, since there is no risk of primary fluid exiting the containment through these fitting ends.

Finally, additional safety is provided by the detector 240, which is able to confirm which inlet port 202 is active, and is further able to detect a breakage in the lines 247 arriving at the inlet sockets 244.

The invention also relates to an installation 290 for producing activated probes in the core of a heavy water nuclear reactor, in particular a CANDU reactor, as shown schematically in Figure 12, comprising:

- a device for subjecting probes to irradiation in the core of a nuclear reactor, extending into the core of the nuclear reactor and intended for receiving probes in view of their irradiation in the core of the nuclear reactor;

- a probe supply system 300, configured for supplying non-activated probes to the device for subjecting probes to irradiation in the core of a nuclear reactor;

- a decay station 330 configured for receiving the probes irradiated in the core of the nuclear reactor from the device for subjecting probes to irradiation in the core of a nuclear reactor,

- a probe discharge system 350 for discharging the probes from the installation 290, the inlet of the probe discharge system 350 being connected to the decay station 330; and

- a probe drive system 370, configured for transporting the probes through the installation 290.

The probe drive system 370 is preferably a pneumatic system.

The probe supply system 300, the probe discharge system 350 and the probe drive system 370 are known and are therefore not described in detail.

The installation 290 may further comprise a diverter 200 as described above, each inlet tube 208 being connected to a respective probe receiving finger 60 of the device 55 for subjecting probes to irradiation in the core of a nuclear reactor and the outlet tube 216 of the diverter 200 being connected to one or both of the decay station 330 and the probe discharge system 350.

In particular, the outlet tube 216 may be connected to a connection part 217 including one inlet port connected to the outlet tube 216 and two outlet ports, one outlet port connected to the decay station 330 and one outlet port connected to the probe supply system 300. Therefore, the diverter 200 may be used both for transporting the activated probes from the device for subjecting probes to irradiation in the core of a nuclear reactor, extending into the core of the nuclear reactor to the decay station 330 and for transporting non-activated probes from the probe supply system 300 to the device for subjecting probes to irradiation in the core of a nuclear reactor, extending into the core of the nuclear reactor. The direction of the transport is determined by the direction of pressurized gas flow through the diverter 200, which is controlled by the probe drive system 370.

Preferably, the device for subjecting probes to irradiation in the core of a nuclear reactor is a device 55 for subjecting probes to irradiation in the core of a nuclear reactor as described above with reference to Figures 6 to 8.