Patent Description:
Radioactive nuclides are used in various fields of technology and science, as well as for medical purposes. These radionuclides are produced in research reactors or cyclotrons. However, since the number of facilities for commercial production of radionuclides is limited already and expected to decrease, it is desired to provide alternative production sites.

The neutron flux density in the core of a commercial nuclear reactor is measured, inter alia, by introducing solid spherical probes into instrumentation tubes passing through the reactor core. It was therefore suggested that instrumentation tubes of commercial nuclear reactors shall be used for producing radionuclides when the reactor is in power generating operation. In particular, one or more instrumentation tubes of an aero-ball measuring system of a commercial nuclear reactor can be used, and existing components of the ball measuring system can be modified and/or supplemented to enable an effective production of radionuclides during reactor operation.

In this context, <CIT> or <CIT> describe installations and methods for producing radionuclides in an instrumentation tube system of a nuclear reactor.

These installations are, however, not entirely satisfactory.

Indeed, the delivery intervals for the radionuclides requested by the clients are generally shorter than the time required for the generation of the radionuclides through exposure to neutron flux in the core of the nuclear reactor. Since only few instrumentation tubes are available for producing the radionuclides, it is not possible, using the radionuclide production installations described above, to reduce the production interval and provide radionuclides with the frequency requested by the clients.

In addition, the activation of the irradiation targets in the core of the nuclear reactor results in the production of the desired radionuclides, but also of short-lived highly radioactive isotopes as by-products. For example, the production of Lutetium-<NUM> in the core of a nuclear reactor results in the generation of a highly radioactive isotope of Ytterbium as a by-product. In addition, highly radioactive isotopes of aluminum are formed as by-products in the case where the irradiation targets comprise an envelope containing aluminum.

Due to their high radioactivity, these by-product isotopes should not be handled by the conventional radionuclide discharge systems described in the above-mentioned patent applications, since this would result in an unacceptably high radiation transmission to the environment, as these discharge systems are designed for the less-radioactive radionuclides which are to be produced by the installation, and not for these by-product isotopes.

One solution for discharging the activated irradiation targets, containing both the desired radionuclide(s) and the short-lived by-products, into conventional storage containers is to add a hot cell for receiving the activated irradiation targets prior to discharging them into the storage containers. However, the construction of such a hot cell is very expensive and the hot cell further occupies a high amount of space, which makes it difficult to provide such a hot cell in the case of commercial nuclear reactors, where the available space is limited.

Therefore, one purpose of the invention is to provide a system which allows delivering radionuclides with a delivery interval which is shorter than the activation time needed for producing the radionuclides in the core of the nuclear reactor, and which further makes it possible to discharge the activated irradiation targets from a structure of a core of a nuclear reactor in a cost effective and compact manner, while minimizing the risk for the environment.

For this purpose, use can be made of a decay station configured for receiving irradiation targets from a structure of a core of a nuclear reactor in a predetermined linear order, comprising a housing comprising a radiation shielding, configured for shielding the environment of the decay station from the radiation emitted by the irradiation targets contained in the decay station,
the housing delimiting a decay conduit intended for containing the irradiation targets in the predetermined linear order, the decay conduit comprising:.

The decay station allows for a transfer of a specific amount of irradiation targets into the decay station, either for temporary storage of partially activated irradiation targets or for allowing for a decay of the short-lived radioisotopes of the activated irradiation targets to an acceptable level prior to their discharge into storage containers.

The possibility of transferring a specific amount of irradiation targets contained in the decay station back into the core of the nuclear reactor by means of the inlet distributor and associated counter makes it possible to produce batches of radioisotopes with a delivery interval which is shorter than the activation time required for the production of the radioisotopes in the core within one same instrumentation finger. For example, it is possible to produce batches of radioisotopes with a delivery interval corresponding to half the activation time required for the production of the radioisotopes in the core.

In particular, the decay station may receive, in this linear order, from the inlet to the outlet of the decay station, a batch of partly activated irradiation targets, having spent only a fraction of the required activation time in the core and a batch of fully activated irradiation targets, having spent the required activation time in the core. The inlet distributor then allows selectively transferring only the partly activated irradiation targets back into the core, after having introduced a number of non-activated irradiation targets into the core, while retaining the fully activated irradiation targets in the decay station for further decay of the short-lived by-product isotopes, prior to the discharge of the fully activated irradiation targets into storage containers through an adapted discharge system.

This decay station therefore also allows discharging the fully activated irradiation targets into conventional storage containers without need for a hot cell or for manipulators by allowing an intermediate storage of the fully activated irradiation targets within the discharge circuit of the system for a duration sufficient for the activity of the short-lived radioisotopes to decrease to an acceptable level. Once the radioactivity level has decreased below a predetermined threshold, the activated irradiation targets may automatically be transferred out of the decay station and into the discharge system of the installation for producing activated irradiation targets.

The transfer into and out of the decay station may occur automatically, without any manual handling, as would be required, for example, in the case of a hot cell.

In addition, the decay station may be integrated directly into existing radionuclide generation installations with little additional effort, while allowing for a safe decay of the short-lived highly radioactive by-product isotopes. In this respect, the decay station may be inserted at any location on the path of the irradiation targets from the core of the nuclear reactor to the discharge system, thus allowing for a high flexibility.

The decay station according to the invention therefore constitutes a cost effective and compact solution for discharging the activated irradiation targets from the core of the nuclear reactor, while minimizing the risk for the environment.

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

The invention relates to a diverter for an installation for producing activated irradiation targets in a nuclear reactor according to claim <NUM>.

This diverter is advantageous, since it is compact, and allows selectively transferring the targets to different destinations directly, i.e. without need for additional intermediate transfer operations.

The diverter may further comprise one or more of the features of claims <NUM> to <NUM>, taken alone or according to any technically possible combination.

The invention also relates to an installation for producing activated irradiation targets according to claim <NUM> or claim <NUM>.

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:.

The invention contemplates that a commercial nuclear reactor can be used for producing artificial radioisotopes or radionuclides, during reactor operation. In particular, conventional aero-ball measuring systems or other systems comprising tubes, for example instrumentation tubes, extending into and/or through the reactor core of the commercial reactor can be modified and/or supplemented to enable an effective and efficient production of radionuclides, when the reactor is in an energy generating mode.

Some of the guide tubes for example of a commercial aero-ball measuring system or Traversing Incore Probe (TIP) system are used to guide the irradiation targets containing the precursor of the desired radionuclide into an instrumentation tube in the reactor core and to lead the activated irradiation targets out of the reactor core.

<FIG> illustrates an installation <NUM> for producing activated irradiation targets <NUM> within a commercial nuclear power plant <NUM>. As opposed to a research reactor, the purpose of a commercial nuclear reactor is the production of electrical power. Commercial nuclear reactors typically have a power rating of <NUM>+ Megawatt electric.

The basis of the installation <NUM> for producing activated irradiation targets <NUM> described in the example embodiments is derived from a conventional Aero-ball Measuring System (AMS) used to measure the neutron flux density in the core10 of the nuclear reactor.

The aero-ball measuring system includes a pneumatically operated drive system configured to insert the aero-balls into an instrumentation finger and to remove the aero-balls from the respective instrumentation finger after activation. Typically, the instrumentation fingers extend into and pass the core <NUM> through its entire axial length. A plurality of aero-balls are arranged in a linear order in an instrumentation finger, thereby forming an aero-ball column. The aero-balls are substantially spherical or round probes but can have other forms such as ellipsoids or cylinders, as long as they are capable of moving through the conduits of the instrumentation tube system.

Referring to <FIG>, a commercial nuclear reactor comprises an instrumentation tube system <NUM> including at least one instrumentation finger <NUM> passing through the reactor core <NUM> of the nuclear reactor. The instrumentation tube system <NUM> is configured to permit insertion and removal of irradiation targets <NUM> into the instrumentation fingers <NUM>.

The irradiation targets <NUM> comprise 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.

The envelope encapsulates the core in a hermetic manner. It is for example made of a material which is not activated neutron flux, for example of a material comprising polyether ether ketone (PEEK). The envelope may preferably comprise a portion made of a metallic material so as to allow for an improved detection, for example using an inductive sensor.

The core in particular comprises the precursor material in powder form.

More preferably, the irradiation targets <NUM> consist of the precursor material, which converts to a desired radionuclide upon activating by exposure to neutron flux present in the reactor core <NUM> of an operating commercial nuclear reactor. Useful precursor materials are Mo-<NUM>, Yb-<NUM> and Lu-<NUM>, which are converted to Mo-<NUM> and Lu-<NUM>, respectively. It is understood, however, that the invention is not limited to the use of a specific precursor material.

Conduits <NUM> of the instrumentation tube system <NUM> penetrate an access barrier <NUM> of the reactor and are coupled to one or more instrumentation fingers <NUM>. Preferably, the instrumentation fingers <NUM> penetrate the pressure vessel cover of the nuclear reactor, with the instrumentation fingers <NUM> extending from the top to the bottom over substantially the entire axial length of the reactor core <NUM>. A respective lower end of the instrumentation fingers <NUM> at the bottom of the reactor core <NUM> is closed and/or provided with a stop so that the irradiation targets <NUM> inserted into the instrumentation finger <NUM> form a column wherein each target <NUM> is at a predefined axial position.

The activation of the targets <NUM> is preferably optimized by positioning the irradiation targets <NUM> in predetermined areas of the reactor core having a neutron flux sufficient for converting a parent material in the irradiation targets <NUM> completely into the desired radionuclide.

The proper positioning of the irradiation targets <NUM> may be achieved by means of dummy targets <NUM> made of an inert material, preferably a magnetic material, and sequencing the dummy targets <NUM> and the irradiation targets <NUM> in the instrumentation tube system <NUM> so as to form a column of the targets <NUM>, <NUM> within the instrumentation finger <NUM>. In fact, the irradiation targets <NUM> are at pre-calculated optimum axial positions in the reactor core <NUM> and the other positions are occupied by the inert dummy targets <NUM> or remain empty. However, it is preferred to use as many positions within the instrumentation fingers <NUM> for irradiation targets <NUM> instead of dummy targets <NUM> to produce as many radionuclides as possible.

The optional dummy targets <NUM> are made of an inert material, which is not substantially activated under the conditions in the reactor core <NUM> of an operating nuclear reactor. Preferably, the dummy targets <NUM> can be made of inexpensive inert materials and can be re-used after a short decay time so that the amount of radioactive waste is further reduced. More preferably, the dummy targets are magnetic.

The installation <NUM> is adapted to handle irradiation targets <NUM> and dummy targets <NUM> having a round, cylindrical, elliptical or spherical shape and having a diameter corresponding to the clearance of the instrumentation finger <NUM> of the aero ball measuring system.

The targets <NUM>, <NUM> preferably a round shape, preferably a spherical or cylindrical shape, so that the targets <NUM>, <NUM> may slide smoothly through and can be easily guided in the instrumentation tube system <NUM> by pressurized gas, such as air or nitrogen, and/or under the action of gravity.

Preferably, the diameter of the targets <NUM>, <NUM> is in the range of between <NUM> to <NUM>, preferably about <NUM>.

According to a preferred embodiment, the commercial nuclear reactor is a pressurized water reactor. More preferably, the instrumentation tube system <NUM> is derived from a conventional aero-ball measuring system of a pressurized water reactor (PWR) such as an EPR™ or Siemens™ PWR nuclear reactor.

The person skilled in the art will however recognize that the invention is not limited to use of an aero-ball measuring system of a PWR reactor. Rather, it is also possible to use the instrumentation tubes of the Traversing Incore Probe (TIP) system of a boiling water reactor (BWR), the view ports of a CANDU reactor and temperature measurement and/or neutron flux channels in a heavy water reactor.

As shown in <FIG>, the installation <NUM> comprises an irradiation target feed system <NUM> configured for providing non-activated irradiation targets <NUM> to the instrumentation tube system <NUM>.

The irradiation target feed system <NUM> comprises a feed tube <NUM> comprising an outlet end intended to be connected to the instrumentation tube system <NUM>. The irradiation target feed system <NUM> further comprises a supply unit <NUM> configured for supplying irradiation targets <NUM>, and optionally dummy targets <NUM> to the installation <NUM>. The supply unit <NUM> is configured to be connected to an inlet end of the feed tube <NUM>. The supply unit <NUM> for example comprises a container, a funnel or a cartridge containing non-activated irradiation targets <NUM> and/or dummy targets <NUM>.

In the example shown in <FIG>, the irradiation target feed system <NUM> further comprises a stopper <NUM> configured for blocking movement of the irradiation targets <NUM> and optional dummy targets <NUM> through the feed tube <NUM>. This stopper <NUM> may be a magnetically or pneumatically operated pin.

The irradiation targets <NUM> provided by the irradiation target feed system <NUM> are non-activated irradiation targets <NUM>, i.e. irradiation targets <NUM> which have not been subjected to any irradiation in the core <NUM> of the nuclear reactor, and which do not contain any radioactive isotopes.

As shown in <FIG>, the installation <NUM> further comprises a target drive system <NUM> configured to transport the irradiation targets <NUM> and optional dummy targets <NUM> through the installation <NUM>.

The target drive system <NUM> is in particular configured to drive the targets <NUM>, <NUM> from the feed system <NUM> into the instrumentation fingers <NUM> in a predetermined linear order and to force the irradiation targets <NUM> and dummy targets <NUM> out of the instrumentation finger <NUM> thereby retaining the linear order of the targets <NUM>, <NUM>.

Preferably, the target drive system <NUM> is pneumatically operated using pressurized gas such as nitrogen or air. Such a system allows for a fast processing of the irradiation targets <NUM> and optionally the dummy targets <NUM>.

More preferably, the target drive system <NUM> comprises one or more pneumatically operated valve batteries (not shown) for separate control of the insertion and transport of the irradiation targets <NUM> and optionally dummy targets <NUM> in the instrumentation tube system <NUM>. The valve batteries of the target drive system <NUM> may be implemented as a further subsystem in addition to the valve batteries of the conventional aero-ball measuring system, or a separate target drive system <NUM> is installed.

Within the feed system <NUM>, the transfer of the irradiation targets <NUM> and optional dummy targets <NUM> from the supply unit <NUM> into the feed tube <NUM> may occur under the effect of gravity or may be driven by the target drive system <NUM>.

The installation <NUM> further comprises an irradiation target discharge system <NUM> configured to receive irradiation targets <NUM> from the instrumentation tube system <NUM> and to discharge these irradiation targets <NUM> into a shielded storage container <NUM>. The irradiation target discharge system <NUM> will be described in greater detail below, with reference to <FIG>.

The installation <NUM> according to the invention additionally comprises a decay station <NUM>, connected between the instrumentation tube system <NUM> and the irradiation target discharge system <NUM>.

The decay station <NUM> is configured for receiving partially or fully activated irradiation targets <NUM> from a structure of a core of a nuclear reactor, and in particular driven out of the instrumentation tube system <NUM>.

The decay station <NUM> is in particular intended for holding fully activated irradiation targets <NUM> for a predetermined time so as to allow for a predetermined decay of the activity of these fully activated irradiation targets <NUM> prior to discharging these irradiation targets <NUM> into the storage container <NUM> by means of the irradiation target discharge system <NUM>.

Preferably, the decay station <NUM> is located outside the reactor core <NUM>, but preferably within accessible areas inside the reactor containment. The decay station <NUM> will be described in more detail below with reference to <FIG> and <FIG>.

In the embodiment shown in <FIG>, the installation <NUM> comprises a diverter <NUM> configured for alternatively creating a path for the displacement of the irradiation targets <NUM> and optional dummy targets <NUM>, between the irradiation target feed system <NUM> and the instrumentation tube system <NUM> or between the instrumentation tube system <NUM> and the decay station <NUM>. More particularly, the diverter <NUM> has a first configuration, in which it defines a path for the displacement of the irradiation targets <NUM> and optional dummy targets <NUM> from the instrumentation tube system <NUM> to the decay station <NUM> and a second configuration, in which it defines a path for the displacement of the irradiation targets <NUM> and optional dummy targets <NUM> from the irradiation target feed system <NUM> to the instrumentation tube system <NUM>.

The displacement of the irradiation targets <NUM> and optional dummy targets through the diverter <NUM> is driven by the target drive system <NUM>.

The installation <NUM> further comprises a switching unit <NUM>, configured for placing the diverter <NUM> into the first configuration or the second configuration depending on the needs.

The diverter <NUM> will be described in more detail below with reference to <FIG> and <FIG>.

With reference to <FIG>, the installation <NUM> further comprises an instrumentation and control unit (ICU) <NUM> connected to the irradiation target feed system <NUM>, the instrumentation tube system <NUM>, the target drive system <NUM>, the switching unit <NUM>, the decay station <NUM> and the irradiation target discharge system <NUM>.

Preferably, the ICU <NUM> is also connected to a fault monitoring system <NUM> of the aero-ball measuring system for reporting any errors. The fault monitoring system <NUM> may also be designed without connection to the existing aero-ball measuring system, but be connected directly to a main control room.

In addition, the installation <NUM> comprises an online core monitoring system <NUM> for controlling activation of the irradiation targets <NUM>.

According to an embodiment, the core monitoring system <NUM> and the instrumentation and control unit <NUM> are configured such that the activation process for converting the irradiation targets <NUM> to the desired radionuclide is optimized by considering the actual state of the reactor, especially the current neutron flux, fuel burn-up, reactor power and/or loading. Thus, an optimum axial irradiation position and irradiation time can be calculated for optimum results. It is however not important whether the actual calculation is performed in the ICU <NUM> or by the core monitoring system <NUM> of the aero-ball measuring system.

The decay station <NUM> according to a first example will now be described in more detail with reference to <FIG>.

The decay station <NUM> according to the first example is preferably configured for receiving cylindrical irradiation targets <NUM>, preferably having a circular basis. As described above, the irradiation targets <NUM> preferably have a diameter comprised between <NUM> and <NUM>, and preferably equal to about <NUM>.

The length of each cylindrical irradiation target <NUM> is preferably greater than or equal to twice the diameter of the irradiation targets <NUM>. The upper limit of the length of the cylindrical irradiation targets <NUM> is in particular defined by the radius of curvature of the conduits of the installation <NUM>. The length of each cylindrical irradiation target <NUM> is for example comprised between <NUM> and <NUM>, and more particularly equal to about <NUM>.

The decay station <NUM> comprises a housing <NUM> delimiting a decay conduit <NUM> intended for containing irradiation targets <NUM>, and more particularly partially or fully activated irradiation targets.

The linear order of the irradiation targets <NUM> in the instrumentation tube system <NUM> is retained in the decay station <NUM>.

The installation <NUM> may comprise a separating device <NUM> (shown in <FIG>) located along the path of the targets <NUM>, <NUM> from the instrumentation tube system <NUM> to the decay station <NUM> for removing the optional dummy targets <NUM> such that only irradiation targets <NUM> are transferred into the decay station <NUM>. Preferably, the dummy targets <NUM> are magnetic and the irradiation targets <NUM> are non-magnetic, and the separating device <NUM> comprises an optional magnetic device, for example comprising an electromagnet, arranged along the path of the targets <NUM>, <NUM> from the instrumentation tube system <NUM> to the decay station <NUM> and configured for retaining only the dummy targets <NUM>. In this respect, when present, the dummy targets <NUM> are generally arranged below the irradiation targets <NUM> in the instrumentation finger <NUM> such that the irradiation targets <NUM> are located in front of the dummy targets <NUM> when the targets <NUM>, <NUM> are driven from the instrumentation tube system <NUM> towards the decay station <NUM>. The dummy targets <NUM> and the separating device <NUM> are optional.

The decay conduit <NUM> preferably has a circular cross-section. The inner diameter of the decay conduit <NUM> substantially corresponds to the outer diameter of the irradiation targets <NUM>.

The housing <NUM> comprises a radiation shielding <NUM>, configured for shielding the environment of the decay station <NUM> from the radiation emitted by the partially or fully activated irradiation targets <NUM> contained in the decay station <NUM>, and in particular for limiting the amount of radiation radiating from the inside of the decay station <NUM> into the environment thereof.

The radiation shielding <NUM> is made of a material adapted for absorbing or reflecting radiation, and in particular alpha, gamma and/or beta radiation. According to one example, the radiation shielding <NUM> is made of lead or tungsten or combinations thereof.

The thickness of the radiation shielding <NUM> is chosen in particular depending on the nature of the radionuclides that are to be received in the decay station <NUM>, and in particular depending on the amount of radiation emitted. Preferably, the thickness of the radiation shielding <NUM> is chosen so as to be able to obtain a dose in the environment outside of the decay station <NUM> smaller than or equal to a predetermined threshold. The predetermined threshold is for example equal to <NUM>µSv/h at a distance of <NUM> from the decay station <NUM>.

The radiation shielding <NUM> preferably extends over the entire circumferential outer surface of the housing <NUM>. In particular, the radiation shielding <NUM> forms the wall of the housing <NUM> delimiting the decay conduit <NUM>.

The decay conduit inlet <NUM> forms the inlet of the decay station <NUM>, while the decay conduit outlet <NUM> forms the outlet of the decay station <NUM>.

The decay conduit inlet <NUM> is more particularly intended to be connected to the instrumentation tube system <NUM> in the first configuration of the diverter <NUM>.

Preferably, the length of the decay conduit <NUM> between the inlet <NUM> and the outlet <NUM> thereof is equal to or greater than the length of the activation zone of the instrumentation tube system <NUM> such that all the irradiation targets <NUM> activated in the instrumentation tube system <NUM> fit into the decay conduit <NUM>. The activation zone corresponds to the zone of the instrumentation tube system <NUM> intended to receive the irradiation targets <NUM> for their activation in the core. In particular, the length of the decay conduit <NUM> between the inlet <NUM> and the outlet <NUM> thereof is greater than or equal to the length of the instrumentation finger <NUM>.

In the first example, shown in <FIG>, the decay conduit <NUM> extends in a rectilinear manner from the decay conduit inlet <NUM> to the decay conduit outlet <NUM>.

As shown in <FIG>, the decay conduit <NUM> is preferably inclined downwards from the decay conduit inlet <NUM> to the decay conduit outlet <NUM>. This inclination prevents the irradiation targets <NUM> from moving towards the decay conduit inlet <NUM> in the absence of an additional force directed towards the decay conduit inlet <NUM>.

According to an alternative (not shown), the decay conduit <NUM> extends substantially horizontally.

The housing <NUM> is for example substantially cylindrical.

The decay station <NUM> additionally comprises:.

The first and second pressurized gas supplies <NUM>, <NUM> are shown only schematically in <FIG>.

The first and second pressurized gas supplies <NUM>, <NUM> are in particular part of the irradiation target drive system <NUM>. For example, the first and second pressurized gas supplies <NUM>, <NUM> are connected to a common pressurized gas supply source <NUM> of the irradiation target drive system <NUM>.

As shown in <FIG>, the decay station <NUM> additionally comprises an inlet distributor <NUM>, located at the decay conduit inlet <NUM>, and configured for releasing only a predetermined amount of irradiation targets <NUM> at a time from the decay station <NUM> towards the instrumentation tube system <NUM>, while retaining at least some irradiation targets <NUM>, and in particular the remaining number of irradiation targets <NUM>, in the decay station <NUM>. The inlet distributor <NUM> is configured for releasing the irradiation targets <NUM> closest to the decay conduit inlet <NUM>.

The inlet distributor <NUM> is configured for clamping an irradiation target <NUM> in the decay conduit <NUM> so as to retain it against a flow of pressurized gas circulating through the decay conduit <NUM>.

The predetermined amount of irradiation targets <NUM> is smaller than the total number of irradiation targets <NUM> that may be received in the decay station <NUM>.

The inlet distributor <NUM> is preferably configured for releasing only the predetermined amount of irradiation targets <NUM> at a time from the decay station <NUM> towards the instrumentation tube system <NUM> and to retain at least some irradiation targets <NUM>, and in particular the remaining number of irradiation targets <NUM>, in the decay station <NUM>, regardless of the magnetic properties of the irradiation targets <NUM>, and in particular through mechanical operation.

More particularly, the inlet distributor <NUM> successively comprises, in a direction from the decay conduit inlet <NUM> toward the decay conduit outlet <NUM>:.

The inlet distributor <NUM> further comprises:.

The lock element <NUM> and the retainer <NUM> are configured for allowing gas flow there-through in the locking, respectively extended, positions thereof.

The lock element <NUM> for example comprises a lock pin <NUM>, configured to extend radially across the decay conduit <NUM> in the locking position so as to block the passage of the irradiation targets <NUM>. More particularly, the lock pin comprises an actuation end, connected to the first actuator <NUM> and a free end, opposite the actuation end. In the extended position, the free end of the lock pin <NUM> abuts against an inner surface of the decay conduit <NUM>. In the extended position, the lock pin <NUM> extends from one side of the decay conduit <NUM> to an opposite side thereof, along a diameter of the decay conduit <NUM>. In particular, the length of the lock pin <NUM> is greater than or equal to the diameter of the decay conduit <NUM>.

In the release position, the lock element <NUM> is preferably retracted into the housing <NUM>, and does not protrude into the decay conduit <NUM>.

The first actuator <NUM> is for example a pneumatic, magnetic or hydraulic actuator.

In the extended position, the retainer <NUM> clamps the irradiation targets <NUM> against which it abuts against the inner wall of the decay conduit <NUM>. The retainer <NUM> is configured for exerting a force, in particular a radial force, onto the irradiation target <NUM> against which it abuts in the extended position which is sufficient for retaining this irradiation target <NUM> against the force exerted by the flow of pressurized gas flowing through the decay conduit <NUM>.

The second actuator <NUM> is for example a pneumatic, magnetic or hydraulic actuator.

The retainer <NUM> for example comprises a retainer pin <NUM> configured to extend radially into the decay conduit <NUM> in the extended position and a spring element (not shown), connected to the retainer pin <NUM>. The spring element reduces the risk of damaging the irradiation target <NUM> against which the retainer pin <NUM> abuts when the retainer <NUM> moves into its extended position. According to a particular example, the second actuator <NUM> is configured for carrying out a linear movement, which is transmitted to the spring, whose force acts on the irradiation target <NUM>. The second actuator <NUM> further comprises a stop, which limits the range of the linear movement of the second actuator <NUM> to a predetermined range. The force exerted on the irradiation target <NUM> by the retainer pin <NUM> is therefore limited by the stiffness of the spring, as well as by the predetermined movement range of the second actuator <NUM>. It is in particular independent of the force exerted by the second actuator <NUM>.

The distance between the lock element <NUM> and the retainer <NUM> is chosen in such a manner that only the predetermined amount of irradiation targets <NUM> may be accommodated between the lock element <NUM> and the retainer <NUM>. More particularly, the distance between the lock element <NUM> and the retainer <NUM> is strictly greater than the cumulated length of the predetermined amount of irradiation targets <NUM> and strictly smaller than the cumulated length of predetermined amount of irradiation targets <NUM> increased by one irradiation target <NUM>. In this case, when the lock element <NUM> is in its locking position and the retainer <NUM> is in its extended position, the predetermined amount of irradiation targets <NUM> may be accommodated in the portion of the decay conduit <NUM> located between the lock element <NUM> and the retainer <NUM>, and the retainer <NUM> abuts against the irradiation target <NUM> located immediately next to the irradiation target <NUM> of the predetermined amount of irradiation targets <NUM> located farthest away from the decay conduit inlet <NUM>.

According to a preferred embodiment, the predetermined amount of irradiation targets <NUM> distributed by the inlet distributor <NUM> is equal to one. In this case, the inlet distributor <NUM> is configured for releasing the irradiation targets <NUM> one by one from the decay station <NUM> towards the instrumentation tube system <NUM>. In addition, the distance between the lock element <NUM> and the retainer <NUM> is preferably chosen in such a manner that only one irradiation target <NUM> may be accommodated between the lock element <NUM> and the retainer <NUM>. More particularly, the distance between the lock element <NUM> and the retainer <NUM> is strictly greater than the length of one irradiation target <NUM> and strictly smaller than the length of two irradiation targets <NUM>. In this case, when the lock element <NUM> is in its locking position and the retainer <NUM> is in its extended position, only one irradiation target <NUM> may be accommodated in the portion of the decay conduit <NUM> located between the lock element <NUM> and the retainer <NUM>, and the retainer <NUM> abuts against the irradiation target <NUM> immediately adjacent to this irradiation target <NUM>. For example, the distance between the lock element <NUM> and the retainer <NUM> is equal to about <NUM> times the length of the irradiation target <NUM>.

The decay station <NUM> further comprises a controller <NUM> (see <FIG>), configured to control the release of the predetermined amount of irradiation targets <NUM> by the inlet distributor <NUM> by controlling a release sequence comprising the following succession of steps:.

The above release sequence results in the release of only the predetermined amount of irradiation targets <NUM> from the decay station <NUM> through the decay conduit inlet <NUM>, while the remaining irradiation targets <NUM> are retained in the decay station <NUM>.

According to a particular example, the controller <NUM> is configured for repeating the release sequence a number of times depending on the total amount of irradiation targets <NUM> that are to be released from the decay station <NUM> through the decay conduit inlet <NUM>.

For example, in the preferred example where the predetermined amount of irradiation targets <NUM> is equal to one, if a number of irradiation targets <NUM> equal to N is to be released from the decay station <NUM> through the inlet distributor <NUM>, the controller <NUM> is configured for repeating the above sequence of steps N times, where N is different from one.

The controller <NUM> may in particular be part of the ICU <NUM> described above.

For introducing the irradiation targets <NUM> into the decay station <NUM> from the instrumentation tube system <NUM>, the lock element <NUM> and the retainer <NUM> are positioned in their release, respectively retracted positions.

The decay station <NUM> further comprises an inlet counter <NUM>, located at the decay conduit inlet <NUM>, and configured for counting the number of irradiation targets <NUM> passing by the inlet counter <NUM>. The inlet counter <NUM> is thus configured for counting the number of irradiation targets <NUM> entering or exiting the decay conduit <NUM> through the decay conduit inlet <NUM>.

The inlet counter <NUM> is a device capable of detecting the passage of an irradiation target <NUM> in front of the inlet counter <NUM>. It is in particular chosen among an inductive sensor, capable of measuring the change of the inductive or dielectric field of a passing irradiation target <NUM>, a pressure sensor, capable of measuring a pressure difference occurring at the passage of an irradiation target <NUM>, an optical sensor, capable of optically detecting the passage of an irradiation target <NUM>, for example a laser sensor or a contrast sensor, a dielectric sensor or a radiation sensor, capable of detecting a difference in radiation intensity occurring at the passage of an irradiation target <NUM>.

The number of irradiation targets <NUM> counted by the inlet counter <NUM> is preferably compared to a preset value so as to ensure that the desired number of irradiation targets <NUM> have entered or exited the decay station <NUM> through the decay conduit inlet <NUM>.

In the example shown in <FIG>, the decay station <NUM> further comprises an outlet stopper <NUM>, located at an outlet end thereof, and configured for blocking movement of the irradiation targets <NUM> out of the decay station <NUM> through the decay conduit outlet <NUM>. The outlet stopper <NUM> contributes to ensuring that the irradiation targets <NUM> contained in the decay conduit <NUM> remain in a predetermined position within the decay conduit <NUM> in the absence of a force directed toward the decay conduit inlet <NUM> exerted on the irradiation targets <NUM>, in particular in the absence of a flow of pressurized gas in the direction from the decay conduit outlet <NUM> toward the decay conduit inlet <NUM>.

In the first example, in which the decay conduit <NUM> is inclined downwards from its inlet <NUM> toward its outlet <NUM>, the irradiation targets <NUM> abut against the outlet stopper <NUM> under the effect of gravity, which also contributes to a well-defined positioning of the irradiation targets <NUM> in the decay conduit <NUM>.

The outlet stopper <NUM> is displaceable between a stop position, in which it blocks movement of the irradiation targets <NUM> out of the decay station <NUM> through the decay conduit outlet <NUM> and a release position, in which it allows movement of the irradiation targets <NUM> out of the decay station <NUM> through the decay conduit outlet <NUM>.

In the stop position, the outlet stopper <NUM> preferably allows gas flow there-through.

The outlet stopper <NUM> has a structure which is similar to that of the lock element <NUM> of the inlet distributor <NUM>. For example, it comprises a stop pin <NUM>, configured to extend radially through the decay conduit <NUM> in the stop position of the outlet stopper <NUM> so as to block the passage of the irradiation targets <NUM> and a stop pin actuator <NUM>, configured for displacing the stop pin <NUM> between the stop position and the release position.

More particularly, the stop pin <NUM> comprises an actuation end, connected to the stop pin actuator <NUM> and a free end, opposite the actuation end. In the extended position of the stopper <NUM>, the free end of the stop pin <NUM> abuts against an inner surface of the decay conduit <NUM>. In the extended position, the stop pin <NUM> extends from one side of the decay conduit <NUM> to an opposite side, along a diameter of the decay conduit <NUM>. In particular, the length of the stop pin <NUM> is greater than or equal to the diameter of the decay conduit <NUM>.

In the retracted position, the stop pin <NUM> is preferably retracted into the housing <NUM>, and does not protrude into the decay conduit <NUM>.

The stop pin actuator <NUM> is for example a pneumatic, magnetic or hydraulic actuator.

Optionally, the decay station <NUM> also comprises an inlet stopper <NUM>, located at the decay conduit inlet <NUM>, upstream of the inlet distributor <NUM>, when considering a flow of irradiation targets <NUM> from the inlet toward the outlet. The inlet stopper <NUM> is configured for blocking movement of the irradiation targets <NUM> out of the decay station <NUM> through the decay conduit inlet <NUM>, and in particular back into the instrumentation tube system <NUM>.

The inlet stopper <NUM> has the same structure as the outlet stopper <NUM>, the only difference being that, in the stop position, it blocks movement of the irradiation targets <NUM> out of the decay conduit <NUM> through the inlet thereof.

Optionally, the decay station <NUM> further comprises an outlet distributor <NUM>, located at the decay conduit outlet <NUM>, and configured for releasing only a predetermined amount of irradiation targets <NUM> at a time from the decay station <NUM> through the decay conduit outlet <NUM> and for retaining the remaining irradiation targets <NUM> in the decay conduit <NUM>.

The outlet distributor <NUM> is shown only schematically in <FIG> and is not illustrated in <FIG>. It has the same structure as the inlet distributor <NUM>, except for the fact that the lock element and the retainer of the outlet distributor <NUM> are arranged successively in a direction from the decay conduit outlet <NUM> toward the decay conduit inlet <NUM>. In addition, in the case of the outlet distributor <NUM>, the roles of the inlet and of the outlet are inverted compared to the inlet distributor <NUM>, and the first pressurized gas supply <NUM> is replaced with the second pressurized gas supply <NUM>, the controller <NUM> being configured for activating the second pressurized gas supply <NUM> so as to obtain a flow of pressurized gas through the decay conduit <NUM> from an inlet end thereof.

Optionally, the decay station <NUM> further comprises an outlet counter <NUM>, located at the decay conduit outlet <NUM>, and configured for counting the number of irradiation targets <NUM> passing by it, i.e. in particular exiting the decay conduit <NUM> through the decay conduit outlet <NUM>. The outlet counter <NUM> is a device capable of detecting the passage of an irradiation target <NUM> in front of the outlet counter <NUM>. It has the same structure as the inlet counter <NUM>.

Further optionally, the decay station <NUM> comprises at least one, and for example a plurality of intermediate irradiation target counters <NUM>, arranged along the decay conduit <NUM> between the decay conduit inlet <NUM> and the decay conduit outlet <NUM>, and configured for counting the number of irradiation targets <NUM> present in the decay conduit <NUM> at a given time.

The intermediate irradiation target counter(s) <NUM> are in particular chosen among a temperature sensor and a gamma radiation measurement sensor.

In particular, due to their activation in the core, the irradiation targets <NUM> have a particular temperature, and the presence of an irradiation target <NUM> in the decay conduit <NUM> can therefore be detected based on a temperature measurement. In particular, an irradiation target <NUM> is detected in the core if the temperature measured by the temperature sensor is greater than or equal to a predetermined threshold depending in particular on the features of the radionuclides contained in the irradiation targets <NUM>.

Alternatively, the presence of an irradiation target <NUM> in the decay conduit <NUM> can be detected based on a gamma radiation measurement, each irradiation target <NUM> present in the decay conduit <NUM> emitting a specific amount of gamma radiation depending in particular on the features of the radionuclides contained in the irradiation target <NUM> and of the envelope of the irradiation target <NUM>.

According to one example, and as shown schematically in <FIG>, the decay station <NUM> comprises one intermediate irradiation target counter <NUM> facing each irradiation target <NUM> in the decay conduit <NUM>. In particular, the adjacent intermediate irradiation target counters <NUM> are spaced from each other along the length of the decay conduit <NUM> by a distance corresponding to the length of an irradiation target <NUM> intended to be contained in the decay conduit <NUM>. For example, the adjacent intermediate irradiation target counters <NUM> are spaced by a distance comprised between <NUM> and <NUM>, and for example equal to about <NUM>.

According to an alternative, the number of intermediate irradiation target counters <NUM> may be less than the total number of irradiation targets <NUM> in the decay conduit <NUM>, in particular in the case where a homogeneous material is activated in all the irradiation targets <NUM>. Indeed, in the case where a homogeneous material is activated in the irradiation targets <NUM>, the values measured by the intermediate irradiation target counters <NUM> for some of the irradiation targets <NUM> may be extrapolated for the other irradiation targets <NUM>.

The intermediate irradiation target counter(s) <NUM> are used as a means of confirming the count performed by the inlet counter <NUM> and/or the optional outlet counter <NUM>. They differ from the inlet counter <NUM> and optional outlet counter <NUM> in that the inlet and outlet counters <NUM>, <NUM> are configured for counting targets in movement, whereas the intermediate counters <NUM> are configured for counting stationary targets contained in the decay conduit <NUM>.

In the example shown in <FIG>, the decay station <NUM> further comprises an outlet radiation detector <NUM>, configured for measuring the radiation emitted by the irradiation target <NUM> located in the decay conduit <NUM> at the decay conduit outlet <NUM>, and for example abutting against the outlet stopper <NUM>.

The outlet radiation detector <NUM> may be located in the wall of the housing <NUM> or outside of the housing <NUM> of the decay station <NUM>, in particular above or below the housing <NUM>.

The outlet radiation detector <NUM> is located at a distance from the outlet stopper <NUM>, taken along the length of the decay conduit <NUM>, smaller than or equal to the length of one irradiation target <NUM>.

In the example shown in <FIG>, the outlet radiation detector <NUM> is located at a fixed position at the decay conduit outlet <NUM>.

Optionally, the decay station <NUM> further comprises at least one, and for example a plurality of, intermediate radiation detectors <NUM>, configured for measuring the radiation emitted by the irradiation targets <NUM> at different locations along the length of the decay conduit <NUM> between the inlet <NUM> and the outlet thereof <NUM>.

For example, the decay station <NUM> comprises one radiation detector <NUM>, <NUM> facing each irradiation target <NUM> in the decay conduit <NUM>. In this case, the adjacent intermediate radiation detectors <NUM>, <NUM> are in particular spaced from each other by a distance corresponding to the length of an irradiation target <NUM> intended to be contained in the decay conduit <NUM>. For example, the adjacent radiation detectors <NUM>, <NUM> are spaced apart by a distance comprised between <NUM> and <NUM>, and for example equal to about <NUM>.

The optional intermediate radiation detectors <NUM> are preferably located in the wall of the housing <NUM> or outside of the housing <NUM> of the decay station <NUM>, in particular above or below the housing <NUM>.

The radiation detectors <NUM>, <NUM> may in particular be used for confirming that the radiation, and for example the dose rate, has decreased below a predetermined threshold, thus allowing safe transfer of the activated irradiation targets <NUM> out of the decay station <NUM> into the irradiation target discharge system <NUM>, which is less shielded than the decay station <NUM>.

Using one radiation detector <NUM>, <NUM> per irradiation target <NUM> allows observing single activation deviations of the irradiation targets <NUM>, compared to an embodiment comprising less radiation detectors <NUM>, <NUM>.

According to an alternative, the total number of radiation detectors <NUM> may be less than the total number of irradiation targets <NUM> in the decay conduit <NUM>, in particular in the case where a homogeneous material is activated in all the irradiation targets <NUM>. Indeed, in the case where a homogeneous material is activated in the irradiation targets <NUM>, the values measured by the radiation detectors <NUM>, <NUM> for some of the irradiation targets <NUM> may be extrapolated for the other irradiation targets <NUM>.

The outlet radiation detector and/or the intermediate radiation detectors <NUM> may be a gamma radiation measurement sensor.

The intermediate radiation detectors <NUM> may be used as intermediate irradiation target counters <NUM>. In particular, the intermediate radiation detectors <NUM> may be gamma radiation measurement sensors, which may be used both for measuring the radiation emitted by an irradiation target <NUM> and for detecting the presence thereof.

According to an alternative (not shown), the outlet radiation detector <NUM> is displaceable along the decay conduit <NUM> between the decay conduit inlet <NUM> and the decay conduit outlet <NUM> so as to be able to measure the radiation emitted by the irradiation targets <NUM> at different locations along the length of the decay conduit <NUM>. The outlet radiation detector <NUM> is in particular displaceable into a position at the decay conduit outlet <NUM> so as to be able to measure the radiation emitted by the irradiation target <NUM> located in the decay conduit <NUM> at the decay conduit outlet <NUM>, and in particular abutting the outlet stopper <NUM>.

The radiation detectors <NUM>, <NUM> are configured for monitoring the decay of the irradiation targets <NUM> contained in the decay station <NUM>. They allow discharging from the decay station only the irradiation targets <NUM> which have sufficiently decayed such that the radiation that they emit is below a predetermined threshold.

The radiation detectors <NUM>, <NUM> are in particular configured for measuring the dose rate emitted by the irradiation targets <NUM>.

The controller <NUM> is preferably configured for controlling a displacement of the outlet stopper <NUM> from the stop position into the release position depending on the results of the measurements of the outlet radiation detector <NUM>, the outlet stopper <NUM> being for example displaced into its release position when the measured radiation is equal to or lower than a predetermined threshold.

One possible purpose of the decay station <NUM> being to allow for a decay of the radioactivity of the irradiation targets <NUM> prior to transferring the irradiation targets <NUM> into a less shielded area of the installation <NUM>, such as the irradiation target discharge system <NUM>, this feature allows discharging the irradiation targets <NUM> out of the decay station <NUM> only when the radiation emitted by the irradiation targets <NUM>, and in particular their dose rate, has decreased to a predefined level.

A decay station <NUM>' according to a second example is shown in <FIG>. This decay station <NUM>' has the same features as described above with respect to the first example, the only difference being the shape of the decay station <NUM>'.

As can be seen in <FIG>, in this example, the decay conduit <NUM> is not rectilinear as in the first example. In the second example, the decay conduit <NUM> is U-shaped. It comprises a first decay conduit section <NUM>, a second decay conduit section <NUM> and a bottom <NUM> formed at the conjunction between the first and second decay conduit sections <NUM>, <NUM>. The first and second decay conduit sections <NUM>, <NUM> extend upwards from the bottom <NUM>.

In this second example, the housing <NUM> of the decay station <NUM>' is U-shaped, the walls of the housing <NUM> delimiting the decay conduit <NUM> being in particular formed by the radiation shielding <NUM>. The U-shape of the decay conduit <NUM> ensures a safe storage of the irradiation targets <NUM> in the decay conduit <NUM>.

The decay station <NUM>' according to the second example is preferably configured for receiving spherical irradiation targets <NUM>. The spherical irradiation targets <NUM> in particular have a diameter comprised between <NUM> and <NUM>, and preferably equal to about <NUM>.

The irradiation target discharge system <NUM> will now be described in more detail with reference to <FIG>.

As can be seen in <FIG>, the irradiation target discharge system <NUM> comprises a discharge conduit <NUM> comprising an inlet end connected to the decay conduit outlet <NUM> of the decay station <NUM> and a target exit port <NUM> configured to be coupled to the target storage container <NUM>.

The linear order of the irradiation targets <NUM> discharged from the decay station <NUM> is retained in the discharge conduit <NUM>.

Preferably, the discharge conduit <NUM> is located outside of the reactor core <NUM>, but preferably within accessible areas inside the reactor containment.

The exit port <NUM> is located at a free end of the discharge conduit <NUM>. In the example shown in <FIG>, it comprises a stop valve <NUM> for pressure tight sealing of the discharge conduit <NUM>.

The exit port <NUM> can be positioned above the storage container <NUM> to be filled, or can be coupled and/or removably connected to the assigned storage container <NUM>. The at least one storage container <NUM> preferably has a shielding to minimize an operator's exposure to radiation from the activated irradiation targets <NUM>.

The irradiation target discharge system <NUM> further comprises a discharge stopper <NUM> configured for blocking movement of the irradiation targets <NUM> to the storage container <NUM>. The discharge stopper <NUM> is displaceable between a stop position, in which it blocks movement of the irradiation targets <NUM> to the storage container <NUM> and a release position, in which it allows movement of the irradiation targets <NUM> into the storage container <NUM>. The discharge stopper <NUM> is for example a magnetically or mechanically operated restriction element, preferably a pin crossing the discharge conduit <NUM>.

The irradiation target discharge system <NUM> may comprise, instead or upstream of the discharge stop <NUM>, a discharge distributor (not shown), located at the exit port <NUM>, and configured for releasing only a predetermined amount of irradiation targets <NUM> at a time into the storage container <NUM>, the discharge distributor being configured for releasing the irradiation targets <NUM> closest to the exit port <NUM>, and for retaining the remaining targets in the discharge conduit <NUM>. Preferably, the predetermined amount of irradiation targets <NUM> is equal to one target such that the discharge distributor is configured for releasing only one irradiation target <NUM> at a time from the discharge conduit <NUM>. The structure of the optional discharge distributor is the same as that of the inlet distributor <NUM> of the decay station <NUM>, and will therefore not be described in detail here.

The discharge conduit <NUM> is, in the embodiment shown in <FIG>, substantially rectilinear. In this embodiment, the inclination of the discharge conduit <NUM> is chosen such that the irradiation targets <NUM> are discharged out of the discharge conduit <NUM> under the effect of gravity when the discharge stopper <NUM> is in the release position.

According to an alternative (not shown), the discharge conduit <NUM> is shaped in the shape of an inverse U and comprises a first discharge conduit section, a second discharge conduit section and an apex formed at a conjunction of the first and second discharge conduit sections. The apex is the highest point of the discharge conduit <NUM>, and the first and second discharge tube sections are directed downwardly from the apex. Such a U-shaped discharge tube is for example described in <CIT> filed by the Applicant.

Other profiles of the discharge conduit <NUM> are also possible.

The irradiation target discharge system <NUM> additionally comprises at least one pressurized gas inlet opening <NUM> formed in the wall of the discharge conduit <NUM>. In the embodiment shown in <FIG>, the pressurized gas inlet opening <NUM> is located between the stop valve <NUM> and the discharge stopper <NUM>. It is connected to a pressurized gas supply, for example to pressurized gas source <NUM>, and forms a part of the irradiation target drive system <NUM> of the installation <NUM>.

Optionally, the irradiation target discharge system <NUM> further comprises a radiation detector <NUM> configured for measuring the radiation emitted by the irradiation targets <NUM> contained in the discharge conduit <NUM>, and in particular the radiation dose rate emitted by the irradiation targets <NUM> contained in the discharge conduit <NUM>.

Optionally, the irradiation target discharge system <NUM> may comprise a discharge counter <NUM> configured for counting the number of irradiation targets <NUM> moving into the discharge conduit from the decay station <NUM>. The discharge counter <NUM> is configured for counting the number of irradiation targets <NUM> passing by the discharge counter <NUM>. The discharge counter <NUM> is a device capable of detecting the passage of an irradiation target <NUM> in front of the discharge counter <NUM>. The discharge counter <NUM> has the same structure as the inlet counter <NUM> described above.

Optionally, the installation <NUM> further comprises an instrumentation tube system target counter <NUM>, arranged at the inlet of the instrumentation tube system <NUM> downstream of the diverter <NUM> with respect to the direction of displacement of the targets <NUM>, <NUM> into the instrumentation tube system <NUM>, and configured for counting the number of irradiation targets <NUM> or dummy targets <NUM> moving into or out of the instrumentation tube system <NUM>. The instrumentation tube system target counter <NUM> is in particular a device capable of detecting the passage of a magnetic target in front of the counter <NUM>, for example of a dummy target <NUM>.

Preferably, the instrumentation tube system target counter <NUM> is positioned upstream of an isolation valve of the instrumentation tube system <NUM>, this isolation valve being configured for pressure tight sealing of the instrumentation tube system <NUM>.

Optionally, the irradiation target feed system <NUM> may also comprise such a target counter (not shown), disposed upstream of the diverter <NUM> relative to the direction of displacement of the targets <NUM>, <NUM> into the instrumentation tube system <NUM>.

In the above description, the decay station <NUM> was described as being connected to an instrumentation tube system <NUM> of a core of a nuclear reactor. However, this decay station <NUM> might be connected to other structures of the core of a nuclear reactor than the instrumentation tube system <NUM>, depending on the needs, with the same advantages.

A diverter <NUM> according to a first embodiment will now be described with reference to <FIG>.

As shown in <FIG>, the diverter <NUM> according to the first embodiment comprises:.

More particularly, each connector <NUM>, <NUM>, <NUM> is intended to be connected to a respective conduit for the displacement of the targets <NUM>, <NUM>. For example, the first connector <NUM> is intended to be connected to the decay conduit <NUM> of the decay station <NUM>, the second connector <NUM> is intended to be connected to the feed tube <NUM> of the irradiation target feed system <NUM> and the third connector <NUM> is intended to be connected to a conduit <NUM> of the instrumentation tube system <NUM>.

The first connector <NUM> may be connected to the irradiation target discharge system <NUM> either directly, i.e. without interposition of intermediate systems between the irradiation target discharge system <NUM> and the diverter <NUM> or indirectly, for example by being connected to the decay station <NUM>, as shown for example in <FIG>.

The third connector <NUM> is spaced apart from the first connector <NUM> and the second connector <NUM> along the horizontal direction. In addition, in the example shown in <FIG>, the first connector <NUM> and the second connector <NUM> are substantially aligned along the vertical direction. The third connector <NUM> is for example located at a height intermediate between the heights of the first and second connectors <NUM>, <NUM>.

The displacement of the targets <NUM>, <NUM> through the diverter <NUM> is driven by the target drive system <NUM> described above.

The diverter <NUM> comprises at least one diverter conduit <NUM> which is movable between a first position, in which it connects one of the first connector <NUM> and the second connector <NUM> to the third connector <NUM> so as to define a path for the targets <NUM>, <NUM> from the one of the first connector <NUM> and the second connector <NUM> to the third connector <NUM>, and a second position, in which it does not connect the one of the first connector <NUM> and the second connector <NUM> to the third connector <NUM>.

More particularly, in the example shown in <FIG>, the diverter <NUM> comprises a first diverter conduit 156A and a second diverter conduit 156B.

The geometry of the diverter conduits 156A, 156B is chosen in such a manner that it minimizes the size of the diverter <NUM>. In particular, each diverter conduit 156A, 156B is shaped in such a manner that it induces, along its length, two changes of direction of the targets <NUM>, <NUM> intended to circulate therein. This particular shape of the diverter conduits 156A, 156B provides for a more compact diverter <NUM>, than, for example, an embodiment in which the diverter conduits 156A, 156B are straight along their entire length. Such a compact shape is important, since the space available for the diverter <NUM> within the nuclear reactor is limited.

Each change of direction occurs at a distance from the longitudinal ends of the diverter conduits 156A, 156B.

More particularly, each diverter conduit 156A, 156B comprises a substantially straight end section <NUM>, <NUM> at each end of the diverter conduit 156A, 156B and an intermediate section <NUM>, extending between the end sections <NUM>, <NUM>. The ends sections <NUM>, <NUM> are preferably parallel to each other, and in particular extend substantially horizontally. For example, the central axes of the end sections <NUM>, <NUM> are offset from each other along a direction perpendicular to their longitudinal direction, and in particular along the vertical direction. The offset x is strictly greater than zero, and for example comprised between <NUM> and <NUM>.

In the embodiment shown in <FIG>, the intermediate section <NUM> is curved. Preferably, for each diverter conduit 156A, 156B, the transition between the curved intermediate section <NUM> and each of the substantially straight end sections <NUM>, <NUM> is continuous, i.e. without angles. Preferably, in this embodiment, the central axis of the diverter conduit 156A, <NUM> forms a continuous line. In the example shown in <FIG>, the intermediate section <NUM> bends continuously between its two ends. This continuous bending of the diverter conduit 156A, 156B and the absence of angles along its length allows for a particular smooth displacement of the targets <NUM>, <NUM> through the diverter conduits 156A, 156B, despite the changes of direction.

In the example shown in <FIG>, the intermediate section <NUM> preferably 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 <NUM>, measured along the central axis of the intermediate section <NUM>.

The radius of curvature of each diverter conduit 156A, 156B and the diameter thereof are chosen depending on the length and diameter of the targets <NUM>, <NUM> so as to result in a smooth displacement of the targets <NUM>, <NUM> through the conduits 156A, 156B.

Preferably, the radius of curvature of each diverter conduit 156A, 156B at the junction between each of the end sections <NUM> and the intermediate section <NUM> is comprised between <NUM> and <NUM>. Tests performed by the inventors show that this particular radius of curvature results in a particularly small size of the diverter <NUM> combined with a substantially resistance-free displacement of the targets <NUM>, <NUM> through the diverter conduits 156A, 156B. This geometry is in particular advantageous in the case of cylindrical targets <NUM>, <NUM> with a circular base having a diameter comprised between <NUM> and <NUM> and a length comprised between <NUM> and <NUM>.

According to an alternative embodiment (not shown), the intermediate section <NUM> is straight, rather than curved as shown in <FIG> and described above. This embodiment has the advantage of being easier to manufacture compared to the embodiment with the curved intermediate section <NUM>.

For each diverter conduit 156A, 156B, the absolute value of an angle between the direction of the end sections <NUM>, <NUM> and the central axis of the intermediate section <NUM> and the diameter of the diverter conduit 156A, 156B are chosen depending on the length and diameter of the targets <NUM>, <NUM> so as to result in a smooth displacement of the targets <NUM>, <NUM> through the conduits 156A, 156B.

In this embodiment, for each diverter conduit 156A, 156B, the absolute value of an angle between the direction of the end sections <NUM>, <NUM> and the central axis of the intermediate section <NUM> is comprised between <NUM>° and <NUM>°. Tests performed by the inventors show that this particular angle of inclination of the intermediate section <NUM> results in a particularly small size of the diverter <NUM> combined with a substantially resistance-free displacement of the targets <NUM>, <NUM> through the diverter conduits 156A, 156B. This geometry is in particular advantageous in the case of cylindrical targets <NUM>, <NUM> with a circular base having a diameter comprised between <NUM> and <NUM> and a length comprised between <NUM> and <NUM>.

The first and second diverter conduits 156A, 156B are preferably symmetric relative to a median plane between these two conduits 156A, 156B. The first diverter conduit 156A for example extends downwards from the first connector <NUM> to the third connector <NUM>, while the second diverter conduit 156B extends upwards from the second connector <NUM> to the third connector <NUM>.

The first diverter conduit 156A connects the first connector <NUM> to the third connector <NUM> in its first position so as to define a path for the displacement of the targets <NUM>, <NUM> from the first connector <NUM> to the third connector <NUM>. In this position, in the example shown in <FIG>, the first diverter conduit 156A defines a path for the displacement of the targets <NUM>, <NUM> between the decay station <NUM> and the instrumentation tube system <NUM>. In the configuration of the diverter <NUM> shown in <FIG>, the first diverter conduit 156A is in its first position.

More particularly, in the first position, the ends of the first diverter conduit 156A are aligned respectively with the first connector <NUM> and the third connector <NUM>.

In the second position of the first diverter conduit 156A, the first diverter conduit 156A does not connect the first connector <NUM> to the third connector <NUM>. For example, in the second position, the ends of the first diverter conduit 156A are not aligned with the first connector <NUM> and the third connector <NUM>. Therefore, no displacement of targets <NUM>, <NUM> is possible between the first connector <NUM> and the third connector <NUM>, and therefore, in this particular example, between the decay station <NUM> and the instrumentation tube system <NUM>.

The second diverter conduit 156B connects the second connector <NUM> to the third connector <NUM> in its first position so as to define a path for the displacement of the irradiation targets <NUM>, <NUM> from the second connector <NUM> to the third connector <NUM>. In this position, in the example shown in <FIG>, the second diverter conduit 156B defines a path for the displacement of the targets <NUM>, <NUM> between the irradiation target feed system <NUM> and the instrumentation tube system <NUM>.

More particularly, in the first position, the ends of the second diverter conduit 156B are aligned respectively with the second connector <NUM> and the third connector <NUM>.

In the second position of the second diverter conduit 156B, the second diverter conduit 156B does not connect the second connector <NUM> to the third connector <NUM>. For example, in the second position, the ends of the second diverter conduit 156B are not aligned with the second and the third connector <NUM>, <NUM>. Therefore, no displacement of targets <NUM>, <NUM> is possible between the second connector <NUM> and the third connector <NUM>, and therefore, in this particular example, between the irradiation target feed system <NUM> and the instrumentation tube system <NUM>.

In the configuration shown in <FIG>, the second diverter conduit 156B is in its second position.

The configuration of the diverter <NUM> shown in <FIG> corresponds to the first configuration of the diverter <NUM>. In the configuration shown in <FIG>, the diverter <NUM> defines a path for the displacement of the targets <NUM>, <NUM> from the decay station <NUM> to the instrumentation tube system <NUM>.

The configuration of the diverter <NUM> in which the first diverter conduit 156A is in the second position and the second diverter conduit 156B is in the second position corresponds to the second configuration of the diverter <NUM>. In this configuration, the diverter <NUM> defines a path for the displacement of the targets <NUM>, <NUM> between the irradiation target feed system <NUM> and the instrumentation tube system <NUM>.

Thanks to its structure, in the first configuration of the diverter <NUM>, the diverter <NUM> allows transferring the targets <NUM>, <NUM> directly from the conduit connected to the first connector <NUM>, for example the decay conduit <NUM>, into the conduit connected to the third connector <NUM>, for example the conduit <NUM> of the instrumentation tube system <NUM>, i.e. there is a direct communication between these conduits through the diverter <NUM> in the first configuration of the diverter <NUM>.

In the second configuration of the diverter <NUM>, the diverter <NUM> allows transferring the targets <NUM>, <NUM> directly from the conduit connected to the second connector <NUM>, for example the feed tube <NUM> of the irradiation target feed system <NUM>, into the conduit connected to the third connector <NUM>, for example the conduit <NUM> of the instrumentation tube system <NUM>, i.e. there is a direct communication between these conduits through the diverter <NUM> in the second configuration of the diverter <NUM>.

The diverter <NUM> further comprises an actuator, configured for displacing the least one diverter conduit <NUM> from the second position into the first position and/or from the first position into the second position, for example by rotation or by translation.

In the example shown in <FIG>, the actuator comprises a piston <NUM>. In this example, the piston <NUM> delimits the first and the second diverter conduits 156A, 156B therein.

The piston <NUM> is movable between a first position, shown in <FIG>, in which the first diverter conduit 156A is in its first position and the second diverter conduit 156B in its second position and a second position (not shown) in which the first diverter conduit 156A is in its second position and the second diverter conduit 156B in its first position. The diverter <NUM> is configured such that the first diverter conduit 156A is in its first position when the second diverter conduit 156B is in its second position and vice versa.

The piston <NUM> is preferably a pneumatic piston.

More particularly, in the example shown in <FIG>, the diverter <NUM> comprises a diverter housing <NUM> comprising a first wall <NUM> and a second wall <NUM>, spaced apart from each other, the diverter conduits 156A, 156B extending from the first wall <NUM> to the second wall <NUM>. In the example shown in <FIG>, the first and second walls <NUM>, <NUM> are substantially parallel. The first and second connectors <NUM>, <NUM> are for example provided on the first wall <NUM> and the third connector <NUM> is provided on the second wall <NUM>.

The piston <NUM> is received in the housing <NUM> so as to be able to slide therein along a direction of displacement X relative to the housing <NUM>. The direction of displacement X is, in particular, perpendicular to the axes of the end sections <NUM>, <NUM> of the diverter conduits 156A, 156B, and more particularly vertical.

A first and a second chamber <NUM>, <NUM> are delimited between the piston <NUM> and the housing <NUM>, these chambers <NUM>, <NUM> being located on either side of the piston <NUM> along the direction of displacement X of the piston <NUM>.

The diverter housing <NUM> further comprises an inlet port <NUM>, intended for introducing a pressurized fluid into the first chamber <NUM> so as to displace the piston <NUM> from its first position into its second position and an outlet port <NUM>, intended for allowing removal of air from the second chamber <NUM> during displacement of the piston <NUM>.

The piston <NUM> is configured for returning into its first position in the absence of pressurized fluid in the first chamber <NUM>. In this embodiment, the first position of the piston <NUM> corresponds to a passive safety position, since it connects the instrumentation tube system <NUM> to the decay station <NUM>, and therefore to an area with a strong radiation shielding.

In the example shown in <FIG>, the first diverter conduit 156A is located above the second diverter conduit 156B, and the piston <NUM> is configured for moving upwards from the first position to the second position and downwards from the second position to the first position.

The diverter <NUM> preferably includes sealing means <NUM> configured for sealing a space between the piston <NUM> and the first and second walls <NUM>, <NUM> of the diverter housing <NUM>. The sealing means <NUM> are for example provided in the form of sealing rings extending around the circumference of the piston <NUM>.

The longest dimension of the piston <NUM> in a plane perpendicular to the direction of displacement of the piston <NUM> depends on the offset x between the end sections <NUM>, <NUM> of the conduits 156A, 156B and on the geometry of each of the conduits 156A, 156B, in particular on the angle between the end sections <NUM>, <NUM> and the intermediate section <NUM> or the radius of curvature at the junction between the end sections <NUM>, <NUM> and the intermediate section <NUM>.

The diverter housing <NUM> is, in particular, cylindrical, for example with a circular base. In this case, the first and second connectors <NUM>, <NUM> are for example formed on one base of the cylinder, and the third connector <NUM> is formed on an opposite base of the cylinder. The piston <NUM> has a shape corresponding to that of the diverter housing <NUM>, in particular cylindrical with a circular base, the diameter of the base substantially corresponding to that of the diverter housing <NUM>.

In this embodiment, the actuator also includes the pressurized gas supply for the displacement of the piston <NUM>.

The switching unit <NUM> is configured for controlling the supply of a predetermined amount of pressurized gas to the first chamber <NUM> so as to displace the piston <NUM> from its first position into its second position, and therefore place the diverter <NUM> into its second configuration. Displacement of the piston <NUM> from the second position into the first position is obtained in the absence of injection of pressurized gas into the first chamber <NUM>.

A diverter <NUM>' according to a second embodiment will now be described with reference to <FIG>. On this figure, the elements which are identical to those shown in <FIG> in relation with the diverter <NUM> according to the first embodiment are designated by the same reference numerals.

The diverter <NUM>' according to the second embodiment differs from the diverter <NUM> according to the first embodiment in that there is only one diverter conduit <NUM>. More particularly, the diverter conduit <NUM> connects the first connector <NUM> to the third connector <NUM> in the first position thereof, and the second connector <NUM> to the third connector <NUM> in the second position thereof.

In this embodiment, the diverter conduit <NUM> is rotatable between the first position and the second position.

More particularly, in this embodiment, the diverter <NUM>' comprises a support <NUM>, for example a plate, on which the first and second connectors <NUM>, <NUM> are provided, and a rotatable conduit carrier <NUM>, for example a disc, which is mounted on the support <NUM> so as to be rotatable relative thereto about an axis of rotation R perpendicular to a plane of the support <NUM>.

One end <NUM> of the diverter conduit <NUM> is mounted onto the rotatable conduit carrier <NUM> such that the rotation of the rotatable conduit carrier <NUM> displaces the diverter conduit <NUM> between its first position and its second position. The axis of rotation R is aligned with the axis of the end section <NUM> of the diverter conduit <NUM> located opposite the end of the diverter conduit <NUM> mounted onto the rotatable conduit carrier <NUM>.

Depending on the angular position of the rotatable conduit carrier <NUM>, the end section <NUM> of the diverter conduit <NUM> closest to the support <NUM> is either in alignment with the first connector <NUM> or with the second connector <NUM>, respectively defining a path for the displacement of the targets <NUM>, <NUM> from the first connector <NUM> to the third connector <NUM> or from the second connector <NUM> to the third connector <NUM>.

The position of the end section <NUM> of the diverter conduit <NUM> does not change during the rotation of the rotatable conduit carrier <NUM>.

For example, in the example shown in <FIG>, in which the first connector <NUM> is located above the second connector <NUM> and vertically aligned therewith, a rotation of the diverter conduit <NUM> about the axis of rotation R of <NUM> degrees in a first direction of rotation D brings the diverter conduit <NUM> from its first position into its second position, and a rotation of the diverter conduit <NUM> about the axis of rotation R of <NUM> degrees in a second direction, opposite to the first direction of rotation D brings the diverter conduit <NUM> from its second position into its first position.

The third connector <NUM> is in particular fixedly received in a fixed support structure (not shown). The fixed support structure is for example formed by a plate, which in particular extends parallel to the plate forming the support <NUM>. The fixed support structure and the support <NUM> may in particular be part of a diverter housing additionally comprising at least one connection wall connecting the fixed support structure to the support <NUM>. The diverter housing may be analogous to that shown in <FIG>.

The end section <NUM> of the diverter conduit <NUM> is connected to the third connector <NUM> through an intermediate connector <NUM>, which allows for a relative rotation of the diverter conduit <NUM> relative to the third connector <NUM>. The intermediate connector <NUM> is for example a quick coupling system comprising two separate parts 185A, 185B, which are rotatable relative to one another, and thus allow for the relative rotation of the diverter conduit <NUM> relative to the third connector <NUM>.

In this embodiment, the actuator for example comprises a motor, configured for rotating the diverter conduit <NUM> in the first or second direction of rotation by a predetermined angle so as to displace it between the first position and the second position. The motor is more particularly connected to the rotatable conduit carrier <NUM> by any adapted means so as to drive the rotation of the rotatable conduit carrier <NUM> in the first or second direction of rotation by a predetermined angle.

The switching unit <NUM> is configured for controlling the motor depending on the needs.

The geometry of the diverter conduit <NUM> is identical to that described for the diverter conduits 156A, 156B.

A method for producing activated irradiation targets <NUM> using the installation <NUM> described above comprises the following steps:.

The method according to a first example will now be described more particularly with reference to <FIG>.

According to the first example, the predetermined irradiation duration d<NUM> being strictly smaller than the minimum activation time required for complete conversion of the precursor material contained in the irradiation targets <NUM> to a desired radionuclide.

Therefore, the first quantity q<NUM> of irradiation targets <NUM> obtained at the end of step <NUM> is a first quantity q<NUM> of partially activated irradiation targets <NUM>. During step <NUM>, this first quantity q<NUM> of partially activated irradiation targets <NUM> is passed from the instrumentation tube system <NUM> into the decay station <NUM>.

The method according to this example further comprises the following successive steps between the steps <NUM> and <NUM>:.

Preferably, during step <NUM>, the irradiation targets <NUM> discharged from the decay station <NUM> into the target storage container <NUM> are fully activated irradiation targets <NUM>.

The "passing" steps mentioned above are carried out by the target drive system <NUM>.

During the step <NUM>, the partially activated irradiation targets <NUM> are transferred out of the decay station <NUM> through the inlet distributor <NUM>, which only lets a predetermined amount A of irradiation targets <NUM> pass at a time, while retaining the remaining irradiation targets <NUM> in the decay station <NUM>.

More particularly, for releasing the predetermined amount A of irradiation targets <NUM>, the following steps are carried out:.

Preferably, the flow of pressurized gas remains activated throughout steps a2 to a4.

More particularly, during step a3, the retainer <NUM> abuts against the irradiation target <NUM> facing the retainer <NUM>, this irradiation target <NUM> extending on either side of the retainer <NUM> along the length of the decay conduit <NUM>.

The quantity q<NUM> is preferably a multiple of the predetermined amount A of irradiation targets such that q<NUM>=m*A, where m is an integer greater than or equal to one, and preferably strictly greater than one.

In the case where m is strictly greater than one, during step <NUM>, the above-sequence of steps a1 to a4 is repeated m times such that the quantity q<NUM> of irradiation targets <NUM> is released from the decay station <NUM>.

In the preferred example where the predetermined amount A of irradiation targets <NUM> is equal to one, the above sequence of steps a1 to a4 is repeated q<NUM> times.

Preferably, during step <NUM>, the inlet counter <NUM> counts the number of irradiation targets <NUM> transferred from the decay station <NUM> into the instrumentation tube system <NUM>, and the above sequence of steps a1 to a4 is repeated until the quantity q<NUM> of irradiation targets <NUM> has been transferred to the instrumentation tube system <NUM>.

During step <NUM>, the quantity q<NUM> of partially activated irradiation targets <NUM> from the decay station <NUM> is transferred into the instrumentation finger <NUM> in which the quantity q<NUM> of irradiation targets <NUM> passed into the instrumentation finger <NUM> during step <NUM> is contained, and occupies positions in this instrumentation finger <NUM> located above the quantity q<NUM> of non-activated irradiation targets <NUM>.

Therefore, at the end of the step <NUM>, the instrumentation finger <NUM> contains, in a direction from the bottom to the top thereof, the quantity q<NUM> of non-activated irradiation targets and the quantity q<NUM> of partially activated irradiation targets <NUM>.

Step <NUM> is a step of discharging the quantity q1 of fully activated irradiation targets <NUM> from the decay station <NUM>.

During this step, the quantity q<NUM> is discharged through the decay station outlet <NUM> of the decay station <NUM> and passed into the discharge system <NUM> by means of the target drive system <NUM>.

According to one example, during step <NUM>, the outlet stopper <NUM> is opened and the irradiation targets <NUM> are carried into the discharge conduit <NUM> by a flow of pressurized gas flowing in a direction from the inlet <NUM> to the outlet <NUM> of the decay conduit <NUM> until they abut against the discharge stopper <NUM>. The discharge stopper <NUM> is then opened such that the irradiation targets <NUM> may be discharged into a corresponding discharge container <NUM>.

In the example in which the decay station <NUM> comprises an outlet distributor <NUM>, the quantity q<NUM> is discharged through the decay station outlet <NUM> in batches corresponding to the predetermined amount by carrying out steps a1 to a4 as described above, where "inlet" is replaced with "outlet" and "outlet" is replaced with "inlet".

Optionally, the radiation, and in particular the dose rate, emitted by the quantity q<NUM> of irradiation targets <NUM> present in the discharge conduit <NUM> is measured by the outlet radiation detector <NUM> and/or by the optional intermediate radiation detectors <NUM>, prior to discharging the irradiation targets <NUM> from the decay station <NUM>, the irradiation targets <NUM> being discharged only if the measured radiation, and in particular dose rate, is below a predetermined threshold.

During step <NUM>, only the quantity q<NUM> of fully activated irradiation targets <NUM> is discharged from the decay station <NUM>. According to a preferred example, only the quantity q<NUM> of irradiation targets <NUM> is present in the decay station <NUM> at the time of discharging the quantity q<NUM> of fully activated irradiation targets <NUM>.

Preferably, the method comprises, between steps <NUM> and <NUM>, a step <NUM> of passing the quantity q<NUM> of fully or partially activated irradiation targets <NUM> and the quantity q<NUM> of partially activated irradiation targets <NUM> into the decay station <NUM>.

Step <NUM> is carried out by the target drive system <NUM>. During step <NUM>, the first and second quantities of irradiation targets <NUM> are preferably driven into the decay station <NUM> by the irradiation target drive system <NUM> until they abut against the outlet stopper <NUM> of the decay station <NUM>, or, if an outlet distributor <NUM> is present, against the lock element of the outlet distributor <NUM>.

The linear order of the irradiation targets <NUM> is retained during this step, such that the quantity q<NUM> of fully or partially activated irradiation targets <NUM> is located closer to the decay conduit outlet <NUM> than the quantity q<NUM> of partially activated irradiation targets <NUM>.

After step <NUM>, a quantity q<NUM> of non-activated irradiation targets <NUM> is passed into the instrumentation tube system <NUM> (step <NUM>) and the quantity q<NUM> of partially activated irradiation targets <NUM> is passed back into the instrumentation tube system <NUM> through implementation of step a1 to a4 described above using the target drive system <NUM> (step <NUM>).

At the end of step <NUM>, the instrumentation finger <NUM> contains, in a direction from the bottom to the top thereof, the quantity q<NUM> of non-activated irradiation targets <NUM> and the quantity q<NUM> of partially activated irradiation targets <NUM>.

After step <NUM>, the method comprises a step <NUM> of exposing the irradiation targets <NUM> contained in the instrumentation finger <NUM> to neutron flux in the core <NUM> of the nuclear reactor for a predetermined irradiation duration d<NUM> so as to obtain a quantity q<NUM> of partially activated irradiation targets <NUM> and a quantity q<NUM> of fully activated irradiation targets.

Steps <NUM>, <NUM>, <NUM> and <NUM> may be repeated a plurality of times, each repetition resulting in a batch of fully activated irradiation targets <NUM> being produced. Each batch of fully activated irradiation targets <NUM> is discharged from the decay station through step <NUM>.

Optionally, the method comprises a step of displacing the diverter <NUM> into the second configuration prior to passing the irradiation targets <NUM> from the irradiation target feed system <NUM> into the instrumentation tube system <NUM> during steps <NUM>, <NUM> and <NUM> and a step of displacing the diverter <NUM> from the second configuration into the first configuration prior to passing the irradiation targets <NUM> from the instrumentation tube system <NUM> into the decay station <NUM> during steps <NUM>, <NUM> and <NUM>.

Preferably, the inlet counter <NUM> counts the number of irradiation targets <NUM> transferred from the instrumentation tube system <NUM> into the decay station <NUM> or from the decay station <NUM> into the instrumentation tube system <NUM> in steps <NUM>, <NUM>, <NUM> and <NUM>.

The quantity q<NUM> is preferably equal to the quantity q<NUM>.

Preferably, all the irradiation durations during which the irradiation targets <NUM> are exposed to neutron flux in the core of the nuclear reactor, for example d<NUM>, d<NUM> and d<NUM>, are identical.

According to one example, each of these irradiation durations is equal to half minimum activation time for complete conversion of the precursor material contained in the irradiation targets <NUM> to a desired radionuclide. In this case, the quantity q<NUM> of irradiation targets <NUM> obtained at the end of step <NUM> and the quantity of irradiation targets <NUM> located at the top of the instrumentation finger <NUM> at the end of step <NUM> are fully activated irradiation targets <NUM>. These fully activated irradiation targets may thus be retrieved from the installation <NUM> with a retrieval period corresponding to half the activation time of the desired radionuclide.

In fact, each of these irradiation durations may correspond to a fraction equal to <NUM>/M of the minimum activation time for complete conversion of the precursor material contained in the irradiation targets <NUM> to a desired radionuclide. The integer M is chosen depending on the relationship between the desired retrieval interval and the minimum activation time for complete conversion of the precursor material contained in the irradiation targets <NUM> to a desired radionuclide. In this case, the instrumentation finger <NUM> comprises may comprise irradiation targets <NUM> in M different stages of activation at the end of step <NUM>, and the irradiation targets <NUM> of each batch have to be exposed M times to neutron flux in the core <NUM> before being fully activated. In such a case, the quantity q<NUM> of irradiation targets <NUM> obtained at the end of step <NUM> is only partially activated, and these irradiation targets <NUM> have to be returned into the instrumentation finger <NUM> for exposure to neutron flux as many times as necessary for achieving the minimum activation time.

Optionally, the method additionally comprises, after step <NUM> and before discharging the fully activated irradiation targets <NUM> in step <NUM>, a step of holding the fully activated irradiation targets <NUM> in the decay station <NUM> for a decay duration d<NUM>.

The decay duration d<NUM> corresponds to the time required for the radiation, and in particular the dose rate, emitted by the quantity q<NUM> of fully activated irradiation targets <NUM> to fall below a predetermined threshold. According to one example, the decay duration d<NUM> is predetermined depending on the nature of the material contained in the irradiation targets <NUM>. According to an alternative, the decay duration d<NUM> depends on the measurement of the radiation, and in particular the dose rate, by the outlet radiation detector <NUM> and/or by the optional intermediate radiation detectors <NUM>.

According to this option, step <NUM> is carried out after the quantity of fully activated irradiation targets <NUM> has been held in the decay station <NUM> for the decay duration d<NUM>.

According to one particular example, batches of N irradiation targets are to be delivered at a delivery interval equal to half the minimum activation time for complete conversion of the precursor material contained in the irradiation targets <NUM> to a desired radionuclide, optionally increased by the decay duration d<NUM> necessary for the radiation, and in particular the dose rate, emitted by the quantity q<NUM> of fully activated irradiation targets <NUM> to fall below a predetermined threshold.

In this particular example, all of the predetermined irradiation durations are equal to <NUM>% of the minimum activation time for complete conversion of the precursor material contained in the irradiation targets <NUM> to a desired radionuclide.

In step <NUM> of the method, N non-activated irradiation targets <NUM> are passed into an instrumentation finger <NUM> from the irradiation target feed system <NUM>.

In step <NUM>, these N non-activated irradiation targets <NUM> are subjected to neutron flux in the core of the nuclear reactor for a time equal to half the minimum activation time for complete conversion of the precursor material contained in the irradiation targets <NUM>.

In step <NUM>, these N partially activated irradiation targets <NUM> are transferred into the decay station <NUM>.

In step <NUM>, N non-activated irradiation targets <NUM> are passed into the instrumentation finger <NUM> from the irradiation target feed system <NUM>.

In step <NUM>, the N partially activated irradiation targets <NUM> are passed into the instrumentation finger <NUM> from the decay station <NUM> such that the instrumentation finger contains, from bottom to top, N non-activated irradiation targets <NUM> and N partially-activated irradiation targets <NUM>.

In step <NUM>, the irradiation targets <NUM> contained in the instrumentation finger <NUM> are subjected to neutron flux in the core of the nuclear reactor for a time equal to half the minimum activation time for complete conversion of the precursor material contained in the irradiation targets <NUM> so as to obtain N fully activated irradiation targets <NUM> and N partially activated irradiation targets <NUM>.

In step <NUM>, the N fully activated irradiation targets <NUM> and N partially activated irradiation targets <NUM> are passed from the instrumentation finger <NUM> into the decay station <NUM>, the linear order of the irradiation targets <NUM> being preserved. The N fully activated irradiation targets <NUM> are thus located closer to the outlet of the decay station <NUM> than the N partially activated irradiation targets <NUM>.

The N fully activated irradiation targets <NUM> are then discharged into a discharge container <NUM> in step <NUM>. Optionally, they remain in the decay station <NUM> for the predetermined decay duration d4 prior to their discharge in step <NUM>.

In step <NUM>, the N partially activated irradiation targets <NUM> stored in the decay station <NUM> are passed from the decay station <NUM> into the instrumentation finger <NUM> such that the instrumentation finger contains, from bottom to top, N non-activated irradiation targets <NUM> and N partially-activated irradiation targets <NUM>.

Steps <NUM> to <NUM> may be repeated as often as necessary, each repetition of these steps resulting in the production of a batch of N fully activated irradiation targets <NUM> with a production duration equal to half the minimum activation time for complete conversion of the precursor material contained in the irradiation targets <NUM> to a desired radionuclide. This batch may then be discharged through step <NUM>, after an optional decay duration d<NUM> in the decay station <NUM>.

The installation <NUM> described above preferably comprises a controller <NUM> configured for implementing the above-described method.

In particular, the installation <NUM> for producing activated irradiation targets, and for example the ICU <NUM>, optionally comprises a controller <NUM> configured for controlling the following steps carried out by the installation <NUM>:.

The above-described decay station <NUM> and installation <NUM> are advantageous.

Indeed, the decay station <NUM> allows for a transfer of a predetermined amount of irradiation targets <NUM> into the decay station <NUM>, either for temporary storage of partially activated irradiation targets <NUM> prior to being transferred back into the core <NUM> of the nuclear reactor for further activation by means of the inlet distributor <NUM> or for the decay of the short-lived radioisotopes of the activation to an acceptable level prior to their discharge into storage containers <NUM>.

The possibility of transferring a predetermined amount of irradiation targets <NUM> contained in the decay station <NUM> back into the core <NUM> offered by the decay station <NUM> allows for a production of batches of radioisotopes with a delivery interval which is smaller than the activation time of the radioisotopes in the core within one same instrumentation tube system <NUM>. For example, it is possible to produce batches of radioisotopes with a delivery interval corresponding to half the activation time of the radioisotopes in the core.

In particular, the decay station <NUM> may receive, in this linear order, from the inlet to the outlet of the decay station, a batch of partly activated irradiation targets <NUM>, having spent only a fraction of the required activation time in the core and a batch of fully activated irradiation targets, having spent the required activation time in the core <NUM>. The inlet distributor <NUM> and associated inlet counter <NUM> then allow selectively transferring only the partly activated radioisotopes back into the core <NUM>, while retaining the fully activated irradiation targets <NUM> in the decay station <NUM>.

The decay station <NUM> also allows discharging the fully activated irradiation targets <NUM> into conventional storage containers <NUM> without need for a hot cell or for manipulators by providing for an intermediate storage of the fully activated irradiation targets <NUM> within the discharge circuit of the installation <NUM> for a duration sufficient for the activity of the short-lived radioisotopes to decrease to an acceptable level. Once the radioactivity level has decreased below a predetermined threshold, the activated irradiation targets <NUM> may automatically be transferred out of the decay station <NUM> and into the discharge system <NUM> of the installation <NUM>. In addition, this decay station <NUM> may be integrated directly into existing radionuclide generation systems with little additional effort, while allowing for a safe decay of the short-lived highly radioactive by-product isotopes.

This decay station <NUM> therefore constitutes a cost effective and compact solution for discharging the activated irradiation targets <NUM> from the core <NUM> of the nuclear reactor, while minimizing the risk for the environment.

The method described above allows reducing the delivery interval of the radioisotopes contained in the fully activated irradiation targets <NUM>. Indeed, at each moment in time, the instrumentation finger <NUM> contains at least two batches of irradiation targets <NUM> at different activation stages. The decay station <NUM> serves as an intermediate storage for a partially activated batch, while a new batch of non-activated targets <NUM> is introduced into the instrumentation finger <NUM>. Once the new batch has been introduced into the instrumentation finger <NUM>, the batch of partially activated irradiation targets <NUM> can be transferred back into the instrumentation finger <NUM> for further exposure to neutron flux. The particular structure of the decay station <NUM> with its inlet distributor <NUM> and associated inlet counter <NUM> makes it possible to transfer only one of the two batches of irradiation targets back into the instrumentation finger <NUM>, while the other batch remains in the decay station <NUM> prior to being discharged into a corresponding discharge container, possibly after having been held in the decay station <NUM> for the decay time d3 to allow for sufficient decay of the short-lived highly radiating isotopes.

According to a second example, the method for producing activated irradiation targets <NUM> using the installation <NUM> described above comprises steps of:.

The decay duration corresponds to the time required for the radiation, and in particular the dose rate, emitted by the quantity q<NUM> of fully activated irradiation targets <NUM> to fall below a predetermined threshold. According to one example, the decay duration is predetermined depending on the nature of the material contained in the irradiation targets <NUM>. According to an alternative, the decay duration depends on the measurement of the radiation, and in particular the dose rate, by the outlet radiation detector <NUM> and/or by the optional intermediate radiation detectors <NUM>.

Optionally, the method comprises a step of displacing the diverter <NUM> into the second configuration prior to passing the irradiation targets <NUM> from the irradiation target feed system <NUM> into the instrumentation tube system <NUM> and a step of displacing the diverter <NUM> from the second configuration into the first configuration prior to passing the irradiation targets <NUM> from the instrumentation tube system <NUM> into the decay station <NUM>.

Preferably, the inlet counter <NUM> counts the number of irradiation targets <NUM> transferred from the instrumentation tube system <NUM> into the decay station <NUM>.

The method according to this alternative results in the production of radionuclides with a delivery interval equal to the minimum activation time of the desired radionuclide augmented by the decay duration.

The method according to this alternative is advantageous. Indeed, it improves the safely and reduces radiation contamination to the environment and personnel, since the irradiation targets into the container <NUM> only after decay of the highly radioactive isotope by-products. In addition, it may be carried out automatically, and does not require the use of additional separate installations, such as hot cells. It is therefore easy to implement and requires only little space.

In the above description, the diverter <NUM> was described as part of an installation including a decay station <NUM>. In this case, it is indirectly connected to the irradiation target discharge system <NUM> through the decay station <NUM>. The diverter <NUM> may however also be part of an installation which does not include a decay station <NUM>, and is then connected to the irradiation target discharge system <NUM> directly without a decay station <NUM> interposed there-between.

In addition, the diverter <NUM> has been described as connected to the instrumentation tube system <NUM> of a core of a nuclear reactor. However, the diverter <NUM> may be connected to other structures inside the core of a nuclear reactor than the instrumentation tube system <NUM>, depending on the needs, with the same advantages.

Claim 1:
Diverter (<NUM>) for an installation for producing activated irradiation targets (<NUM>) in a nuclear reactor, the diverter (<NUM>) having a first configuration, in which it defines a path for the displacement of the irradiation targets (<NUM>) between a structure of the core (<NUM>) of the nuclear reactor, in particular an instrumentation tube system (<NUM>), and an irradiation target discharge system (<NUM>) for discharging the activated irradiation targets (<NUM>), and a second configuration, in which it defines a path for the displacement of the irradiation targets (<NUM>) between an irradiation target feed system (<NUM>) and the structure of the core (<NUM>) of the nuclear reactor,
the diverter (<NUM>) comprising :
- a first connector (<NUM>) intended to be connected to the irradiation target discharge system (<NUM>);
- a second connector (<NUM>) intended to be connected to the irradiation target feed system (<NUM>);
- a third connector (<NUM>) intended to be connected to the structure of the core (<NUM>) of the nuclear reactor;
- a first diverter conduit (156A) which is movable between:
- a first position, in which it connects the first connector (<NUM>) to the third connector (<NUM>) so as to define a path for the irradiation targets from the first connector (<NUM>) to the third connector (<NUM>), and
- a second position, in which it does not connect the first connector (<NUM>) to the third connector (<NUM>);
- a second diverter conduit (156B) which is movable between:
- a first position, in which it connects the second connector (<NUM>) to the third connector (<NUM>) so as to define a path for the irradiation targets from the second connector (<NUM>) to the third connector (<NUM>), and
- a second position, in which it does not connect the second connector (<NUM>) to the third connector (<NUM>);
each diverter conduit (156A, 156B) being shaped in such a manner that it induces, along its length, two changes of direction of the irradiation targets intended to circulate therein, and
- an actuator, configured for displacing each diverter conduit (156A, 156B) between its first position and its second position.