RADIONUCLIDE GENERATION SYSTEM

Abstract

A radionuclide generation system comprises a tube system configured to permit insertion and removal of irradiation targets into an instrumentation finger of a nuclear reactor, and an irradiation target drive system configured to insert the irradiation targets into the instrumentation finger and to remove the irradiation targets from the instrumentation finger. The radionuclide generation system further comprises an instrumentation and control unit which is linked to an online core monitoring system and being configured to calculate an optimum irradiation time for the irradiation targets based on the actual state of the reactor as provided by the online core monitoring system.

Claims

1. A radionuclide generation system, the system comprising: a tube system configured to permit insertion and removal of irradiation targets into an instrumentation finger of a nuclear reactor, an irradiation target drive system configured to insert the irradiation targets into the instrumentation finger and to remove the irradiation targets from the instrumentation finger, and an instrumentation and control unit, the instrumentation and control unit being linked to an online core monitoring system and being configured to calculate an optimum irradiation time for the irradiation targets based on the actual state of the reactor as provided by the online core monitoring system.

2. The radionuclide generation system according to claim 1, wherein information provided by the online core monitoring system to the instrumentation and control unit includes at least one of: neutron flux, activation values from an existing ball measuring system, burn-up, reactor power, loading, rod position(s), flow rate, inlet-temperature, pressure, time synchronization.

3. The radionuclide generation system according to claim 1, wherein further parameters are calculated by the instrumentation and control unit from the information provided by the online core monitoring system.

4. The radionuclide generation system according to claim 1, further comprising at least one sensor for detecting ingress of primary coolant.

5. The radionuclide generation system according to claim 4, wherein the sensor is located at a component of the tube system.

6. The radionuclide generation system according to claim 4, wherein the sensor is a humidity sensor based on a spark plug which is modified for measuring electrical resistance.

7. The radionuclide generation system according to claim 1, wherein the drive system comprises a valve battery as a pneumatic system for separate control of transport of the irradiation targets in the tube system.

8. The radionuclide generation system according to claim 1, wherein the tube system comprises a separation component splitting the tubes at a cable bridge above a reactor pressure vessel head and/or at a connector board of the nuclear reactor.

9. The radionuclide generation system according to claim 1, wherein the drive system comprises a target filling device for inserting the irradiation targets into the instrumentation finger and removing the irradiation targets from the instrumentation finger after irradiation for further transport in the tube system.

10. The radionuclide generation system according to claim 1, wherein the instrumentation and control unit is configured such that operation of valves of the target filling device is at least partly automated.

11. The radionuclide generation system according to claim 1, wherein the drive system comprises a gate device for discharging the irradiation targets into a collecting container after irradiation.

12. The radionuclide generation system according to claim 1, wherein the drive system comprises sensors for monitoring the presence and runtime of the irradiation targets and/or indicator balls passing through the tube system.

13. The radionuclide generation system according to claim 12, wherein the sensors for monitoring the presence and runtime of the irradiation targets and/or indicator balls measure radiation and/or variation of magnetic flux as the irradiation targets and/or indicator balls pass by the sensors.

14. The radionuclide generation system according to claim 1, wherein the instrumentation and control unit is linked to at least one fault monitoring system of the nuclear reactor.

15. The radionuclide generation system according to claim 1, wherein an operator station including a process unit for controlling specific operating parameters of the mechanical components of the drive system.

16. The radionuclide generation system according to claim 1, wherein the instrumentation and control unit is configured to automatically control the pressure in the tube system.

17. The radionuclide generation system according to claim 1, wherein electric power for the components of the radionuclide generation system is managed by a load cabinet of a ball measuring system and/or by a control cabinet.

18. The radionuclide generation system according to claim 3, wherein the further parameters calculated by the instrumentation and control unit from the information provided by the online core monitoring system comprise preferred irradiation locations of the irradiation targets in the instrumentation finger.

19. The radionuclide generation system according to claim 5, wherein the sensor is located outside a pressure vessel of the nuclear reactor.

20. The radionuclide generation system according to claim 14, wherein the instrumentation and control unit is linked to a fault monitoring system of a ball measuring system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Further features and advantages of the invention will become apparent from the following description and from the accompanying drawings to which reference is made. In the drawings:

[0028] FIG. 1 shows a schematic sketch of a radionuclide generation system (MAS) setup according to the invention;

[0029] FIG. 2 shows an example of a MAS I & C integration into a ball measuring system;

[0030] FIG. 3 shows an example of modifications of a MAS I & C in a ball measuring system;

[0031] FIG. 4 shows a schematic diagram providing information on the amount of instrumentation fingers, their equipment with ball measuring detectors and their distribution within the core of the nuclear reactor; and

[0032] FIG. 5 shows an instrumentation finger filled partly with MAS aeroballs and partly with indicator balls.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0033] FIG. 1 illustrates the basic setup of a radionuclide generation system within a commercial nuclear power plant, in particular a power plant with an EPR or Siemens DWR nuclear reactor. The basis of the radionuclide generation system is an existing or otherwise planned ball measuring system, the main purpose of which is to measure the neutron flux density in the core of the nuclear reactor. The ball measuring system includes a drive system configured to insert aeroballs into instrumentation fingers, which extend into the core, and to remove the aeroballs from the instrumentation fingers after irradiation.

[0034] The ball measuring system is adapted to also handle special irradiation targets, which are also formed as aeroballs having a diameter of 1.9 mm but include a suitable parent material for generating radionuclides which are to be used for medical and/or other purposes. For easier reference, hereafter the radionuclide generation system based on the existing or planned ball measurement system will be referred to as MAS (Medical Aeroball System).

[0035] As shown in FIG. 1 the instrumentation and control (I & C) of the MAS is linked to a target filling device (infeed/outfeed mechanism), a mechanical control equipment including a valve battery, an adapted online irradiation control system of the ball measuring system, and a fault monitoring system.

[0036] In the following, the major components of the MAS, which are necessary in addition to those of the existing or planned ball measurement system, or which need to be modified, will be described in accordance with FIGS. 2 and 3. The added or modified components are indicated with bold lines and are written in italics in FIGS. 2 and 3.

[0037] A valve battery is used as an additional pneumatic system for separate control of the MAS targets in the tube system. The valve battery may be implemented as a further subsystem in addition to the valve batteries of the ball measuring system, or a whole new system is installed.

[0038] A separation component splits the tubes at the cable bridge above the reactor pressure vessel head, via which the tubes are led out of the reactor well, and/or at the connector board.

[0039] A target filling device (infeed/outfeed mechanism) inserts the MAS aeroballs into the instrumentation fingers and removes them from the instrumentation fingers after irradiation for further transport in the tube system.

[0040] A gate system including several (electro)-mechanical devices is used to fill the irradiation targets into a tube for transport to the reactor core, and also to discharge the MAS aeroballs into a collecting container after irradiation.

[0041] Several humidity sensors are provided to detect any ingress of primary coolant (or any other liquid) into the MAS system. It has to be understood that the instrumentation tubes used for the MAS are in direct contact with the primary cooling water surrounding the core of the nuclear reactor. The humidity sensors may be based on spark plugs which are modified for measuring electrical resistance.

[0042] Further sensors are provided for monitoring the presence and runtime of the MAS aeroballs passing through the tubes. These sensors are preferably arranged at the instrumentation tubes penetrating the core. The measuring principle may be based on the detection of a variation of the magnetic flux as the MAS aeroballs (or any indicator balls for measuring transport time and completeness indication) pass by.

[0043] Via an interface a MAS I & C control unit is connected with the adapted online core monitoring system software. The control unit is further connected to the mechanical components of the MAS, including the sensors. For an efficient generation of radionuclides optimum irradiation conditions and time for the MAS aeroballs are to be determined. Practically all relevant input data for this calculation are available from the online irradiation control system of the ball measuring system, e. g. the POWERTRAX/S core monitoring software system by Areva. Therefore, the control unit, which is linked to this (adapted) system, can calculate the optimum irradiation time and further parameters, like the amount of MAS aeroballs in an instrumentation finger (defining the actual length of the respective target column and the positions of the individual aeroballs within the target column). Based on the results of these calculations the control unit and/or the operator operate the mechanical MAS components accordingly. The control unit is also connected to an updated fault monitoring system of the ball measuring system for reporting any errors in the MAS.

[0044] The online calculation of the optimum irradiation time and other parameters is not simply based on the assumption of an estimated constant neutron flux, but rather takes the actual state of the reactor into account, especially at least one of the following parameters: neutron flux, activation values from an existing ball measuring system, burn-up, reactor power, loading, rod position(s), flow rate, inlet-temperature, pressure, time synchronization. Not only the real-time values of these parameters, but also their development over time may be considered.

[0045] FIG. 4 schematically depicts a diagram providing information on the amount of instrumentation fingers, their equipment of ball measuring detectors and their distribution within the core of the nuclear reactor. According to the example shown in FIG. 4, four ball measuring positions are taken from the ball measuring system for use in the MAS.

[0046] FIG. 5 shows a simplified illustration of an instrumentation finger 10 which is used for the MAS. With the aid of the online core monitoring system it is possible to determine areas 12 of the instrumentation finger in which the neutron flux is too low for producing radionuclides, and areas 14 where the neutron flux is above the required irradiation target demand and thus suitable for producing the desired radionuclides. An upper area 16 of the instrumentation finger 10 may be empty. Having the indicator balls below the targets in the instrumentation finger the sensors monitors that all balls have left the finger during blow out process, if the indicator balls pass the sensor

[0047] FIG. 5 also symbolically shows a humidity sensor 18 that could theoretically be arranged at the instrumentation finger 10, However, the humidity sensors are usually arranged at components of the tube system outside the reactor pressure vessel.

[0048] Manual operation of the MAS is performed at an operator station via a process unit. The process unit is installed at a separate control cabinet in a control cabinet room (cf. FIGS. 2 and 3). The process unit is equipped with a display and allows, inter alia, the controlling of specific parameters of the MAS valve battery.

[0049] At the operator station the state of the MAS irradiation targets during irradiation and the remaining irradiation time can be monitored. When the calculated irradiation time of a set of targets in an instrumentation finger is exceeded, a message prompts the operator to start the outfeed process with respect to this instrumentation finger. The operation of the various valves of the infeed/outfeed mechanism is partly automated so that repeating actions are performed more safely and more reliably.

[0050] After each infeed with new irradiation targets the pressure in the tube system is checked and regulated in a fully automated manner. The control unit also collects further digital signals representative of certain system conditions. Especially, the signals of the humidity sensors allow a leakage monitoring, i. e. to detect whether any primary coolant has entered the tube system of the MAS.

[0051] The electric power for the MAS components, including the valve battery and the process unit of the MAS cabinet, is realized via the load cabinet of the ball measuring system. To this end, a further power inverter with appropriate fuses is installed in the load cabinet. It is also possible to use an additional 24 volt supply incorporated in the control cabinet room.

[0052] The MAS can also be installed in a nuclear power plant without a ball measuring system. The ball measuring system as described above is only the basis that makes an installation of the desired radionuclide generation system easier as no tubes, fingers etc. need to be installed only for the MAS. A possible reactors for such an application could be a CANDU (CANada Deuterium Uranium) reactor.