• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a self-powered neutron detector (200) of a pressurized-water nuclear reactor comprising a tank and a lid (100), said lid having at least one penetration (110) for the passage of a spray lance. instrumentation (120) comprising a sealing device (300), said detector being intended to be introduced inside the core by said instrumentation lance (120) itself passing through said cover (100) of said reactor, said detector (200) being characterized in that it comprises a hollow outer conduit (210) surrounding a single coaxial cable (240) forming neutron detecting means, the outer diameter of said hollow outer conduit (210) being dimensioned to be introduced through said sealing device located in the instrumentation lance (120) passing through said cover (100) of said nuclear reactor.
    公开号:FR3019932A1
    申请号:FR1453311
    申请日:2014-04-14
    公开日:2015-10-16
    发明作者:Jean Lucien Mourlevat
    申请人:Areva NP SAS；
    IPC主号:
    专利说明:

    [0001] BACKGROUND OF THE INVENTION [0001] The invention relates to the field of self-powered neutron detectors present in a pressurized water reactor (PWR). The invention relates more particularly to self-powered neutron detectors introduced by the upper part (i.e. the lid) of a pressurized water reactor. The invention relates more particularly to self-powered neutron detectors slow response but is also applicable to self-powered neutron detectors fast response. STATE OF THE PRIOR ART [0004] Self-powered neutron detectors, also known as "collectrons", have been developed to enable precise and fixed measurement of the power distributions in the core of the reactors. This type of detector is used in pressurized water reactors, as well as in experimental reactors. [0005] Collectrons have a simple structure and operation. They are in the form of a coaxial cable of small diameter (i.e. of the order of 1 to 2 mm). The central core of the coaxial cable (ie the collectron) is composed of two cables and an insulator surrounding said two cables: i) a first cable, a first part sensitive to the neutron flux, called transmitter, is constituted by a isotope generating electrons by means of a neutron / material reaction and a second part is constituted by a metal cable mechanically and electrically connected to the emitter (ie the first part); ii) a second metal cable identical in nature and diameter to the first cable, not connected to the transmitter, called "compensation cable". iii) the two cables are surrounded by an insulator, usually alumina. The whole, that is to say the central core, is surrounded by a metal sheath to form a coaxial cable. The collectrons are placed and maintained inside the reactor core permanently during the operation of the reactor. Most PWR reactors in service are equipped with an instrumentation system of the heart penetrating into the tank from below, through penetrations, called bottom of tank. There are, however, PWR type reactors in which the collectrons are introduced from the top of the tank via penetrations in the tank lid. In this latter category of reactors, self-powered neutron detectors travel in mechanical elements forming the "upper internals" of the reactor located under the tank cover and above the core. The collectrons are classified into two categories: - slow-response collectrons (usually rhodium) for which the neutron / material reaction will give rise to emission by the transmitter, electrons by radioactivity 13-; in this case, the establishment of a stable current is a function of the period of radioactive decay of the isotopes formed; - Fast response collectrons (usually cobalt) for which the neutron / matter reaction will give rise to electron emission by Compton or photoelectric effects following the radiative absorption of neutrons by the transmitter; the response time is less than 30ms but the signal-to-noise ratio is much lower than for slow collectrons. As illustrated figurel, depending on the design of the upper internals, self-powered sensors introduced by the cover 20 of the nuclear reactor 10 are caused to be bent in order to marry better the links located on the one hand between the vertical mechanical assemblies formed by the instrumentation lances 31 ("instrumentation lances" in English), and the horizontal mechanical assemblies 32 (ie the instrumentation arms ("yoke" in English) and secondly between the instrumentation arms 32 (horizontal assemblies) and the vertical instrumentation fingers 33 ("instrumentation finger" in English) plunging into a specific tube called an instrumentation tube within the fuel elements. one of the guide tubes making up the mechanical skeleton of the fuel element or the central tube. [0010] The radii of curvature which derive from these connections, some of which can be at right angles can be very short, of the order of a few centimeters. The number of self-powered rhodium detectors present in the fuel elements is generally six to eight arranged at different levels in the core. Thus, there is a bundle of eight coaxial cables at most, which travels in the upper internals. There can also be a thermocouple so that the number of cables is at most nine. Given the very small geometries and radii of curvature of the collectrons imposed by the upper internals and unlike the PWR type nuclear reactors equipped with an instrumentation system of the heart penetrating into the tank from below, it is impossible to protect this beam through an external conduit that would protect all coaxial cables from direct contact with the water of the primary circuit and therefore from a corrosion phenomenon that could lead to an irreversible loss of electrical insulation and an inability to measure the flow of neutrons. Indeed, the assembly thus formed would be too rigid and could not be bent with the required radii of curvature. In addition, the passage diameters of the neutron detectors at the level of the sealing systems of the instrumentation lances 31 with the cover 20 are historically defined for the passage of fast response collectrons (ie of the order of 2 mm in diameter), making it impossible to fit an outer duct around the collectron beam. Thus, the collectron beam travels naked in the upper internals without external protective conduit, causing direct contact with the water of the primary circuit. SUMMARY OF THE INVENTION [0013] In this context, the invention aims to improve this situation by providing a self-powered neutron detector adapted to be introduced through the lid of a pressurized water nuclear reactor to reduce the risk of corrosion of the reactor. coaxial cable constituting the collectron and thus reduce the risk of loss of the neutron detection function. To this end, the invention relates to a self-powered neutron detector of a pressurized water nuclear reactor comprising a tank and a lid, said lid having at least one penetration for the passage of an instrumentation lance comprising a sealing device, said detector being intended to be introduced inside the core by the instrumentation lance itself passing through the cover of said reactor, said detector being characterized in that it comprises a hollow outer conduit which surrounds a single coaxial cable forming neutron detecting means, the outer diameter of said hollow outer conduit being dimensioned to be introduced through said sealing device located in the instrumentation lance passing through said cover of said nuclear reactor. Thus, the invention provides a self-powered neutron detector introduced through the lid of the tank of a pressurized water nuclear reactor operating in a dry environment, thereby reducing the risk of corrosion under stress of a cable. of the collectron, avoiding the direct contact of the coaxial cable with primary liquid of the reactor, while respecting the geometrical constraints of a neutron detector (whose lengths and diameters of each part of the detector are fixed by the sensitivity of the detector), and the formal requirements imposed by the implantation of an internal neutron instrumentation of the core based on collectrons positioned at fixed locations in a PWR type reactor with respect to the sealing system between the outer conduit and the instrumentation lances at the penetrations of the lid. [0016] Advantageously, the detector according to the invention is a slow-response neutron detector. The invention is particularly adapted to internal instrumentations formed by the combination of slow response neutron detector and fast response neutron detector. Advantageously, the invention proposes a neutron detector, typically of slow response, isolated from the primary coolant of a PWR type reactor by an individual outer pipe whose outside diameter, at the level of the penetration of the lid, is less than or equal to 2mm so that it can be easily installed in the passages of the sealing devices located in the instrumentation lances. Thus, the invention proposes to individually protect each self-powered detector, and particularly rhodium collectron type detectors, in an outer conduit of reduced diameter, and not the entire beam grouping together all the detectors placed in a fuel assembly so that the assembly can be bent according to the radii of curvature required by the implantation of the internal instrumentation in the reactor core and the routing of the cables in the so-called upper internal mechanical elements of the tank. The self-powered neutron detector according to the invention may also have one or more of the following characteristics, considered individually or in any technically possible combination: the external diameter of the hollow outer conduit is less than or equal to 2 millimeters on the along his path in the tank; - The outer diameter of said hollow outer conduit is equal to 1.9 mm at the penetration of the lid; the neutron detector is a slow-response detector comprising a rhodium or vanadium emitter; the neutron detector is a fast response detector comprising a cobalt or platinum or hafnium emitter; the hollow outer conduit is a metal conduit that is not sensitive to stress corrosion phenomena in the primary water of the reactor; the hollow outer conduit is made of stainless steel; the outer conduit is a one-piece and continuous piece; the outer conduit has a plug welded at its end. Advantageously, the internal instrumentation system of a pressurized water nuclear reactor comprises at least one self-powered slow response neutron detector according to the invention and / or at least one self-powered rapid response neutron detector. [0022] Advantageously, the internal instrumentation system of a pressurized water nuclear reactor comprises at least one thermocouple. The invention also relates to a pressurized water nuclear reactor comprising a lid, a tank, a fixed internal instrumentation system according to the invention. BRIEF DESCRIPTION OF THE FIGURES [0024] Other features and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures. FIG. 1 already described in the preamble illustrates an overall view of a nuclear water reactor comprising neutron detectors of the collectron type positioned at fixed locations according to the state of the art. FIG. 2 illustrates a schematic view of a self-powered slow response neutron detector according to the invention. Figures 3 to 6 are different sectional views of the neutron detector according to the invention made according to the reference numerals illustrated in Figure 2. In all the figures, the common elements bear the same references unless otherwise specified. . DETAILED DESCRIPTION OF AN EMBODIMENT [0029] FIG. 2 illustrates a schematic view of a self-powered slow response neutron detector 200 according to the invention in position in a vessel (not shown) of a water nuclear reactor. pressurized, and introduced into the tank through a penetration 110 arranged in the cover 100. Figures 3 to 6 show different cross-sectional views of the neutron detector with the outer conduit according to the invention at different levels in the nuclear reactor. FIG. 3 illustrates a sectional view of the neutron detector 200 according to the invention at the level of the instrumentation lance 120 of a pressurized water nuclear reactor. Figure 4 illustrates a sectional view of the neutron detector 200 according to the invention at the instrumentation arm of a pressurized water nuclear reactor. FIG. 5 illustrates a sectional view of the neutron detector 200 according to the invention at the level of the upper internals of a pressurized water nuclear reactor. FIG. 6 illustrates a sectional view of the neutron detector 200 according to the invention at the level of the reactor core. The slow-response neutron detector 200 according to the invention is a rhodium neutron detector formed by a coaxial cable 240 comprising a central core constituted by: a signal wire 250, for example made of Inconel®, connected to it at its lower end to a rhodium emitter 220, a transmitter 220, for example rhodium or vanadium, electrically and mechanically connected to the signal wire 250, of a length of about ten centimeters, capable of absorbing neutrons then to emit electrons which will be transported by the signal wire, - a compensating wire 230, for example made of Inconel®, - an electrical insulator 270, generally alumina, surrounding the metal wires 250, 230. [0035] The central core is surrounded by a sheath 245, for example Inconel 600 ® thus protecting the two son, signal 250 and compensation 230. [0036] The neutron detector 200 according to the invention also comprises a external wave 210 surrounding the collectron 240 cable along its length, and at least over the entire portion of the cable located inside the reactor vessel. The dimensions of the external duct 210 are imposed in the upper part (at the level of the penetration of the lid) by the dimension of the penetration 110 of the lid 100 as well as by the dimensions of the instrumentation lance 120 and the sealing system 300, and in the lower part by the dimensions of the collectron cable sheath at the neutron-sensitive emitter 220. Indeed, the outer diameter of the coaxial cable 240 at the level of the neutron-sensitive portion, corresponding to the diameter of the rhodium emitter 220 and the diameter of the rhodium emitter 220, are fixed dimensions specific to the detectors. collectron type because their sensitivities as well as their measurement accuracies depend on it. Thus, in a conventional manner, the self-powered rhodium detectors comprise a coaxial cable 240 having an external diameter Del (ca) greater at the level of the neutron sensitive part, symbolized by the reference Z1 in FIG. outer diameter De2 (ca), De3 (ca) of the non-neutron sensitive part. Recall that the external diameter De2 (ca) corresponds to the external diameter of the coaxial cable 240 at the upper internals illustrated in section in Figure 5 and at the horizontal instrumentation arm illustrated in section in Figure 4, and that the diameter external De3 (ca) corresponds to the external diameter of the coaxial cable 240 passing through the penetration 110 of the cover 100 illustrated in Figure 3. [0039] It is therefore at the level of the second part, that is to say at the level of the non-neutron sensitive portion, coaxial cable 240, which has an outer diameter equal to De2 (ac) and which travels in the upper internals at the right-angled junctions located on the one hand between the vertical mechanical assemblies represented by the instrumentation lance 120 and horizontal (instrumentation arm) and on the other hand between the instrumentation arms (horizontal) and the vertical instrumentation fingers, which must be bent according to rayo imposed curvature. Advantageously, the coaxial cable 240 thus formed by the central core and the sheath 245 has a diameter of about 1.1 mm at the non-neutron sensitive portion. In the present invention, the coaxial cable 240 is inserted into an outer conduit 210 having an outer diameter that can be variable. To simplify the description, the outer conduit 210 according to the invention has a constant thickness; however, the present invention is also applicable with an outer conduit 210 having varying thicknesses as the size of the outer conduit meets the various surrounding constraints of the reactor. The thickness of the outer conduit 210 is dimensioned so as to mechanically withstand the pressure of the primary liquid. Thus, in order to meet the constraints of surrounding dimensions, the outer conduit 210 has: - an outer diameter at the level of the instrumentation lance 120 having a value De3 (cd) less than the inside diameter of the lance of instrumentation 120, and typically less than 2 mm; and advantageously of the order of 1.9 mm; an outside diameter of the duct at the level of the instrumentation arm and at the level of the upper internals having a value De2 (cd), advantageously in the embodiment illustrated in FIG. 2, De2 (cd) <De3 (cd) so to facilitate the bending operation of this portion of the outer conduit 210; an outside diameter of the duct at the level of the neutron-sensitive portion having a value Del (cd) less than the inside diameter of the instrumentation lance 120, to possibly allow its passage for the assembly / disassembly operations, and greater than the diameter outside the coaxial cable Del (ca). At the level of the penetration 110 of the cover 100, a sealing system 300 is provided. This sealing system 300 is composed of three levels: a first level of sealing achieved between the cover 100 and the instrumentation lance 120; a second level of sealing achieved between the instrumentation lance 120 and the outer conduit 210 of the detector 200; a third level of sealing achieved between the outer conduit 210 and the coaxial cable 240 of the neutron detector 200, said primary seal; this third level of sealing is individual to each detector 200 composing the beam and is made by a sealing system 30 for example of brazing or "Swagelok" type. Thus, the outer conduit 210 of the detector 200 forms a continuous monobloc sheath, ie without welding except that concerning the plug 215 at its lower end, over its entire length, or at least over the entire portion located inside. of the reactor vessel. By way of example, such a sheath can be manufactured from a hammering process that makes it possible to lengthen the sheath by reducing the diameter of the sheath by hammering. Advantageously, the outer conduit 210 of the detector 200 according to the invention is made of stainless steel. The invention has been particularly described for a self-powered slow-response neutron detector of the collectron rhodium type present in a pressurized water reactor (PWR); however, the invention is also applicable to a fast response auto-reactive neutron detector for example cobalt, platinum or hafnium.
    权利要求:
    Claims (11)
    [0001]
    REVENDICATIONS1. A self-powered neutron detector (200) of a pressurized water nuclear reactor having a vessel and a lid (100), said lid having at least one penetration (110) for passage of an instrumentation lance (120) having a sealing device (300), said detector being intended to be introduced inside the core by said instrumentation lance (120) itself passing through said cover (100) of said reactor, said detector (200) being characterized by it comprises a hollow outer conduit (210) surrounding a single coaxial cable (240) forming neutron detecting means, the outer diameter of said hollow outer conduit (210) being dimensioned to be introduced through said device sealing device located in said instrumentation lance (120) passing through said cover (100) of said nuclear reactor.
    [0002]
    2. Self-powered neutron detector (200) of a pressurized water nuclear reactor according to the preceding claim characterized in that said outer diameter of said hollow outer conduit (210) is less than or equal to 2 millimeters along its path in the tank. .
    [0003]
    3. Self-powered neutron detector (200) of a pressurized water nuclear reactor according to one of the preceding claims characterized in that the outer diameter of said hollow outer conduit (210) is equal to 1.9 mm at the penetration of cover (100).
    [0004]
    4. Self-powered neutron detector (200) of a pressurized water nuclear reactor according to one of the preceding claims, characterized in that said neutron detector is a slow-response neutron detector comprising a rhodium or vanadium emitter (220). .
    [0005]
    5. Self-powered neutron detector (200) of a pressurized water nuclear reactor according to one of the preceding claims, characterized in that said neutron detector is a fast response neutron detector comprising a cobalt or platinum or hafnium emitter
    [0006]
    6. Self-powered neutron detector (200) of a pressurized water nuclear reactor according to one of the preceding claims, characterized in that the hollow outer conduit (210) is a metal conduit that is not sensitive to stress corrosion phenomena in the reactor. primary water reactor.
    [0007]
    7. Self-powered neutron detector (200) of a pressurized water nuclear reactor according to one of the preceding claims, characterized in that the hollow outer conduit (210) is made of stainless steel.
    [0008]
    8. Self-powered neutron detector (200) of a pressurized water nuclear reactor according to one of the preceding claims characterized in that the outer conduit (210) is a single piece and continuous.
    [0009]
    9. Self-powered neutron detector (200) of a pressurized water nuclear reactor according to one of the preceding claims characterized in that the outer conduit comprises a plug (215) welded at its end.
    [0010]
    10. Internal instrumentation system of a pressurized water nuclear reactor characterized in that it comprises at least one self-powered neutron detector according to one of claims 1 to 9.
    [0011]
    11. Internal instrumentation system of a pressurized water nuclear reactor according to the preceding claim characterized in that it comprises at least one thermocouple.
    类似技术:
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    同族专利:
    公开号 | 公开日
    WO2015158523A1|2015-10-22|
    FR3019932B1|2016-05-06|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US3375370A|1965-12-28|1968-03-26|Ca Atomic Energy Ltd|Self-powered neutron detector|
    FR2236192A1|1973-07-05|1975-01-31|Westinghouse Electric Corp|
    FR2430023A1|1978-06-27|1980-01-25|Westinghouse Electric Corp|SELF-SUPPLIED RADIATION DETECTOR|
    US20100091929A1|2007-02-28|2010-04-15|Mitsubishi Heavy Industries, Ltd.|Structure for suppressing flow vibration of instrumentation guide tube|CN104900279A|2015-04-09|2015-09-09|中国核动力研究设计院|Delay elimination method of rhodium detector signal based on Luenberger form H2/H infinity hybrid filtering|
    CN107316665A|2017-06-01|2017-11-03|西安交通大学|A kind of Optimization Design of self-power neutron detector structure|
    CN107300713B|2017-05-23|2019-04-16|西安交通大学|Self-power neutron detector based on deconvolution postpones effect removing method|
    WO2020025115A1|2018-07-31|2020-02-06|Framatome Gmbh|Lance unit and method of producing radionuclides|
    法律状态:
    2015-03-19| PLFP| Fee payment|Year of fee payment: 2 |
    2016-03-23| PLFP| Fee payment|Year of fee payment: 3 |
    2017-03-22| PLFP| Fee payment|Year of fee payment: 4 |
    2018-03-22| PLFP| Fee payment|Year of fee payment: 5 |
    2019-04-29| PLFP| Fee payment|Year of fee payment: 6 |
    2020-04-30| PLFP| Fee payment|Year of fee payment: 7 |
    2021-04-29| PLFP| Fee payment|Year of fee payment: 8 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1453311A|FR3019932B1|2014-04-14|2014-04-14|SELF-DIRECTED NEUTRON DETECTOR OF A PRESSURIZED WATER REACTOR|FR1453311A| FR3019932B1|2014-04-14|2014-04-14|SELF-DIRECTED NEUTRON DETECTOR OF A PRESSURIZED WATER REACTOR|
    PCT/EP2015/056656| WO2015158523A1|2014-04-14|2015-03-26|Self-powered neutron detector of a pressurised-water reactor|
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