JP2010078459A - Device and method for detecting breakage of heat exchanger tube of heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect existence of a breakage and a breakage spot of a heat exchanger tube highly accurately in a short period of time. <P>SOLUTION: This device has: a gas leak first detector 16 and a gas leak second detector 18 for detecting leak of He gas flowing through an aperture between an outer tube and an inner tube of the heat exchanger tube from a breakage spot of the heat exchanger tube in order to confirm existence of a breakage of the heat exchanger tube 11 in a steam generator 10; and a neutron generation device 33 and a neutron detection image sensor 34 arranged oppositely across the heat exchanger tube 11 in order to specify the breakage spot of the heat exchanger tube. Neutrons emitted from the neutron generation device 33 are absorbed by He3 gas flowing through the aperture between the outer tube and the inner tube and leaking from the breakage spot, and a neutron shadow at that time is detected as a two-dimensional image by the neutron detection image sensor 34. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a heat exchanger tube breakage detecting apparatus and method for a heat exchanger, and more particularly to a heat exchanger tube breakage detecting apparatus and method suitable for a steam generator functioning as a heat exchanger in a fast breeder reactor. About.

  Conventionally, in order to detect breakage of a heat transfer tube in a heat exchanger, an eddy current flaw detection (also referred to as eddy current flaw detection) inspection method, an interpolated ultrasonic flaw detection method, and the like have been studied. These methods can only inspect up to 600 heat transfer tubes having a length of 5 m per day even if the amount of treatment is large. If the number of heat transfer tubes increases and the length becomes longer, it takes a longer time to identify a broken portion such as a crack.

  In an actual eddy current flaw inspection method, an operator must disassemble the heat exchanger and carefully inspect the heat transfer tubes one by one, which requires a considerable amount of time. In current petroleum refining, petrochemical, and general chemical plans, sampling inspection methods are widely applied as a method for predicting the life of heat transfer tubes of general heat exchangers. However, in this sampling inspection method, since the inspection is not actually performed for the portions that are not subject to sampling, there is a risk of abnormalities during operation after reassembling the heat exchanger. In addition, disassembling and inspecting the heat exchanger in this way is difficult to apply in a fast breeder reactor steam generator using liquid metal sodium and steam because the metal sodium is liquid. Conceivable.

  As a nondestructive inspection method other than the eddy current flaw detection method, there are a transmission test method using X-rays and γ-rays and a CT method described in Patent Document 1. In the CT method, heat transfer tube groups are imaged by CT (computer tomography) processing using radiation to detect defects in the heat transfer tubes. When a large number of heat transfer tubes exist, these heat transfer tubes overlap, so it is difficult to determine the damaged part from the image by the transmission test method, and the method of detecting an abnormal part from the cross section by the CT method is suitable. It is thought that.

Moreover, in the steam generator of the fast breeder reactor that performs heat exchange between the current liquid metal sodium and steam, as described in Patent Document 2, the heat transfer tube of the steam generator is used for handling the liquid metal sodium. When a double heat transfer tube is used and He gas is allowed to flow through the gap between the outer tube and the inner tube at a positive pressure and the outer tube is damaged, the He gas moves to the liquid metal sodium side. The outer tube is damaged by detecting the concentration. In addition, when the inner pipe is damaged, the steam inside the inner pipe flows into the He gas flowing in the gap between the outer pipe and the inner pipe, so that the moisture concentration in the He gas is detected. Check for damage to the inner tube.
JP 2005-140791 A JP 2000-130965 A

  However, in the CT method disclosed in Patent Document 1, even if radiation is used in a system in which the entire heat exchanger has a diameter of 5 m or more, the amount of change in a defect portion such as a crack with respect to the amount of transmitted radiation is small. It is difficult to detect. Moreover, if the resolution of the cross section of the heat transfer tube to be sliced is set high, the measurement time becomes enormous, and it must be determined that the combination with the current sensor technology is not practical.

  Further, in the heat transfer tube breakage detection method in the steam generator described in Patent Document 2, when a minute leak occurs from the heat transfer tube of the steam generator, for example, when the flow rate of liquid metal sodium is high, the amount of He gas to be sampled is It becomes extremely small amount, and the heat detection accuracy of the heat transfer tube is lowered. Therefore, it takes a long time to detect He gas after the heat transfer tube is defective. Moreover, even if the presence or absence of breakage of the heat transfer tube can be confirmed, it is difficult to identify the breakage point.

  The object of the present invention has been made in consideration of the above-mentioned circumstances, and provides a heat exchanger tube breakage detection device and method for a heat exchanger that can detect the presence or absence and breakage of a heat exchanger tube with high accuracy and in a short time. There is to do.

  The heat exchanger tube breakage detection device for a heat exchanger according to the present invention is a double heat transfer tube in which each of a plurality of heat transfer tubes is composed of an outer tube and an inner tube, the first fluid flowing outside the outer tube, A heat exchanger for exchanging heat with a second fluid flowing inside the inner pipe, wherein the first pipe flowing through the gap between the outer pipe and the inner pipe in order to confirm whether the heat transfer pipe is damaged or not. A gas leakage detector for detecting that the detection gas leaked from the damaged portion of the heat transfer tube; and a neutron generator arranged opposite to the heat transfer tube to identify the damaged portion of the heat transfer tube; A neutron detection image sensor, and neutrons emitted from the neutron generator are absorbed by a second detection gas leaked from the damaged portion through the gap between the outer tube and the inner tube, and the neutrons at that time The shadow of the neutron detection image sensor is 2 It is characterized in that the detection as the original image.

  Moreover, the heat exchanger tube breakage detection method for a heat exchanger according to the present invention is a double heat transfer tube in which each of a plurality of heat transfer tubes is composed of an outer tube and an inner tube, and a first fluid flowing outside the outer tube, A heat exchanger for exchanging heat with the second fluid flowing inside the inner pipe, wherein the first detection gas flowing through the gap between the outer pipe and the inner pipe is from a damaged portion of the heat transfer pipe. The gas leak detector detects that the leak has occurred, and confirms whether or not the heat transfer tube is damaged. When the heat transfer tube is damaged, the neutrons emitted from the neutron generator are Neutron detection image sensor that is absorbed by the second detection gas leaked from the damaged portion through the gap between the neutron generator and the heat transfer tube, and is opposed to the neutron generator and the heat transfer tube Detects the heat transfer as a two-dimensional image. Is characterized in that the identifying the damage.

  According to the heat exchanger tube breakage detecting device and method for a heat exchanger according to the present invention, a gas leak detector detects that the first detection gas flowing through the gap between the outer tube and the inner tube of the heat exchanger tube has leaked from the breakage point of the heat exchanger tube. By detecting whether the heat transfer tube is damaged or not, the neutron from the neutron generator is absorbed by the second detection gas leaked from the damaged portion through the gap between the outer tube and the inner tube, Since the neutron detection image sensor detects the shadow of the neutron, the damaged portion of the heat transfer tube is specified, so the presence or absence of the heat transfer tube and the damaged portion can be detected with high accuracy and in a short time.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, the present invention is not limited to these embodiments.

[A] First embodiment (FIGS. 1 to 8)
FIG. 1 is a schematic configuration diagram showing a heat transfer tube breakage detection device in a steam generator of a fast breeder reactor to which the first embodiment of the heat transfer tube breakage detection device of a heat exchanger according to the present invention is applied. FIG. 2 is a view taken in the direction of arrow II in FIG. FIG. 5 is a pipeline diagram showing a gas supply line for supplying a detection gas for detecting breakage of the heat transfer tubes to the multiple heat transfer tubes in FIG. FIG. 7 is a perspective view showing the heat transfer tube breakage detecting device of FIG.

  The steam generator 10 of the fast breeder reactor shown in FIG. 1 functions as a heat exchanger, and has a large number of helical heat transfer tubes 11 as shown in FIGS. As shown in FIG. 4, each heat transfer tube 11 is a double heat transfer tube including an outer tube 12 and an inner tube 13. In the steam generator 10, heat exchange is performed between the liquid metal sodium Na as the first fluid flowing outside the outer tube 12 and the water or steam W as the second fluid flowing inside the inner tube 13. The water W in the inner pipe 13 becomes steam due to the heat of the liquid metal sodium Na, and this steam W is guided to the steam turbine for power generation.

  In order to confirm whether or not the heat transfer tube 11 is damaged, the He gas as the first detection gas flows at a positive pressure in the gap 14 between the outer tube 12 and the inner tube 13 of the heat transfer tube 11. That is, when the outer tube 12 is broken, the He gas leaks into the liquid metal sodium Na flowing in a large amount at a high speed. Since this He gas is lighter than liquid metal sodium Na, it rises as bubbles in this liquid metal sodium Na. However, because the flow rate of liquid metal sodium Na is high, the bubbles of He gas also flow with the liquid metal sodium Na. . As shown in FIG. 1, the gas leak first detector 16 provided in the outflow pipe 15 of the liquid metal sodium Na in the steam generator 10 detects the concentration of He in the sampled liquid metal sodium Na, Leakage of He gas into the liquid metal sodium Na is detected, and thereby the breakage of the outer tube 12 of the heat transfer tube 11 is confirmed.

  Further, when the inner tube 13 of the heat transfer tube 11 is damaged, the He gas leaks into the water or steam W flowing through the inner tube 13. In the steam generator 10, the gas leak second detector 18 provided in the outflow pipe 17 of the steam W detects the He concentration in the sampled steam W, thereby detecting the leak of He gas to the steam W, Thereby, the damage of the inner pipe 13 is confirmed.

  The second gas leak detector 18 detects the pressure of the He gas flowing through the gap 14 between the outer tube 12 and the inner tube 13 and detects the leakage of the He gas due to the decrease in the pressure. It may be one that confirms breakage, or by detecting the concentration of water or steam (moisture concentration) in the inner pipe 13 that flows into the He gas in the gap 14 of the heat transfer pipe 14, It may be one that confirms damage.

  When the gas leak first detector 16 or the gas leak second detector 18 confirms that the outer tube 12 or the inner tube 13 of the heat transfer tube 11 is broken as described above, the operation of the fast breeder reactor is safely stopped. Is done. However, it is impossible to specify which part of which heat transfer tube 11 is damaged only by the above-described configuration. Therefore, first, a configuration for searching which heat transfer tube 11 is damaged among the multiple heat transfer tubes 11 in the steam generator 10 will be described.

  Supply He gas or He3 gas (described later) as the second detection gas to the gaps 14 between the outer tube 12 and the inner tube 13 in the multiple heat transfer tubes 11 in the steam generator 10 shown in FIGS. As shown in FIG. 5, the gas supply line 20 is connected to a first header 25 communicated with a gas cylinder 21 of He gas and a gas cylinder 22 of He3 gas via switching valves 23 and 24, respectively. A plurality of first gas supply pipes 26 provided with regulating valves 26A and a plurality of second headers 27 connected to the respective first gas supply pipes 26, each having a plurality of flow regulating valves 28A. A plurality of third gas supply pipes 30 connected to the second gas supply pipes 28 and third headers 29 communicated with the respective second gas supply pipes 28 and each having a flow rate adjusting valve 30A, and the following. As well Although not shown, a plurality of nth gas supply pipes connected to an nth (n: natural number) header communicated with the (n-1) th gas supply pipe, each having a flow rate adjusting valve, and a heat transfer pipe 11 and the terminal gas supply pipe 31 connected to the gap 14 between the outer pipe 12 and the inner pipe 13. Thus, the 1st gas supply pipe 26, the 2nd gas supply pipe 28, the 3rd gas supply pipe 30, ... nth gas supply pipe, ... terminal gas supply pipe 31 is constituted by tree structure.

  The first gas supply pipe 26 is a first gas supply pipe, and a plurality of heat transfer pipes 11 in the steam generator 10 are grouped into a plurality of first groups to supply He gas or He3 gas. . That is, when all the heat transfer tubes 11 in the steam generator 10 of FIG. 6A are partitioned into a plurality of (for example, four) first groups A1 to A4, a plurality of (for example, four) first gases. Each of the supply pipes 26 supplies He gas or He3 gas to the gap 14 of the heat transfer pipe 11 belonging to each of these groups A1 to A4.

  The second gas supply pipe 28 shown in FIG. 5 is a second gas supply pipe, and the multiple heat transfer tubes 11 in the first groups A1 to A4 are grouped into a plurality of second groups. He gas or He3 gas is supplied. That is, when the heat transfer tubes 11 of, for example, the group A1 in each of the first groups A1 to A4 in FIG. 6A are divided into a plurality of (for example, four) second groups B1 to B4, a plurality (for example, Each of the four second gas supply pipes 28 supplies He gas or He3 gas to the gap 14 of the heat transfer pipe 11 belonging to each of the groups B1 to B4. Similarly, the plurality of (for example, four) second groups B5 to B8, B9 to B12, and B13 to B16 (both not shown) also belong to each of the first other groups A2 to A4. Each of the plurality of second gas supply pipes 28 supplies He gas or He3 gas to the gap 14 of the heat transfer pipe 11 belonging to each of these groups B5 to B16.

  The third gas supply pipe 30 shown in FIG. 5 is a third gas supply pipe, and the multiple heat transfer tubes 11 in the second groups B1 to B16 are grouped into a plurality of third groups. He gas or He3 gas is supplied. That is, when the heat transfer tubes 11 of, for example, the group B1 in the second groups B1 to B16 of FIG. 6B are divided into a plurality of (for example, two) third groups C1 and C2, a plurality (for example, Each of the two third gas supply pipes 30 supplies He gas or He3 gas to the heat transfer pipes 11 belonging to the groups C1 and C2. Similarly, the heat transfer tubes 11 belonging to each of the second other groups B2 to B16 are divided into a plurality of (for example, two) third groups C3 to C32 (not shown), and a plurality of third groups. Each of the gas supply pipes 30 supplies He gas or He3 gas to the heat transfer pipes 11 belonging to each of these groups C3 to C32.

  An n-th gas supply pipe (not shown) is an n-th gas supply pipe, and a large number of heat transfer tubes 11 in each of the (n−1) -th groups are combined into a plurality of n-th groups to form He gas. Alternatively, He3 gas is supplied.

  In the present embodiment, when searching for which heat transfer tube 11 is damaged, as shown in FIG. 5, the first gas supply tube 26 and the second gas supply tube described above configured in a tree structure are used. 28, the third gas supply pipe 30,... The nth gas supply pipe, etc., are connected to the signals from the gas leak first detector 16 and the gas leak second detector 18, respectively. Then, the control device 32 is remotely operated.

  That is, the control device 32 first opens the switching valve 23 and closes the switching valve 24 in the same manner as during the operation of the fast breeder reactor, and the first gas supply pipe 26, the second gas supply pipe 28, and the like. The He gas in the gas cylinder 21 is supplied to the gaps 14 between the outer tube 12 and the inner tube 13 of the heat transfer tubes 11 belonging to all the first groups A1 to A4 through the third gas supply tube 30 and the like.

  Next, in the first group A1 to A4, the control device 32 detects the first group in which leakage is detected by the gas leakage first detector 16 or the gas leakage second detector 18 (for example, FIG. ) To the second lower group (for example, the groups B1 to B4 in FIG. 6B) connected to the group A1), and gas leakage from these second groups B1 to B4. He gas is supplied to the lower third group (for example, groups C1 and C2 in FIG. 6C) connected to the group (for example, group B1) in which leakage is detected by the first detector 16 or the gas leakage second detector 18. The heat transfer tube 11 in which the He gas is leaked due to supply and repeated is searched for.

  Specifically, when all the flow rate adjustment valves 26 are opened and the He gas is supplied to the gaps 14 of all the heat transfer tubes 11 of the first group A1 to A4, the gas leakage first detector. 16 or when the gas leakage second detector 18 detects the leakage of He gas, the control device 32 sequentially opens any one of the flow rate adjustment valves 26A to select one of the first groups A1 to A4. Gas leakage first detector 16 or gas leakage second detector when He gas is supplied to the gap 14 between any one group of heat transfer tubes 11 and He gas is supplied to any group of heat transfer tubes 11 It is determined whether 18 has detected a leak of He gas.

  If it is determined that the gas leakage first detector 16 or the gas leakage second detector 18 has detected the leakage of He gas when He gas is being supplied to the gap 14 of the heat transfer tube 11 of the group A1, the control is performed. Next, the device 32 sequentially opens any one of the flow rate regulating valves 28A corresponding to the lower groups B1 to B4 connected to the first group A1 among the second groups B1 to B16, He gas is supplied to the gap 14 between the heat transfer tubes 11 of any one of the second groups B1 to B4. And when the control apparatus 32 is supplying He gas to the heat exchanger tube 11 of any group of group B1-B4, the gas leak 1st detector 16 or the gas leak 2nd detector 18 will leak He gas. Determine if it was detected.

  If it is determined that the gas leak first detector 16 or the gas leak second detector 18 has detected the He gas leak when the He gas is being supplied to the gap 14 of the heat transfer tube 11 of the group B1, The control device 32 sequentially opens any one of the flow rate regulating valves 30A corresponding to the lower groups C1 and C2 connected to the second group B1 among the third groups C1 to C32, He gas is supplied to the gap 14 between the heat transfer tubes 11 of any one of the third groups C1 and C2. And the control apparatus 32 is the gas leak 1st detector 16 or the gas leak 2nd detector 18 when He gas is supplied to the heat exchanger tube 11 of any group of the groups C1 and C2. Determine if it was detected.

  By repeating the above operation, the control device 32 searches for the heat transfer tube 11 in which the outer tube 12 or the inner tube 13 is broken and the He gas leaks out. At this time, even when there are a plurality of damaged heat transfer tubes at the same time, it is possible to search for a plurality of damaged heat transfer tubes 11 by executing a plurality of narrowing routes.

  After searching for the heat transfer tube 11 that has been damaged as described above and the He gas has leaked out, a configuration for identifying the damaged portion of the damaged heat transfer tube 11 will be described.

  As shown in FIG. 1 to FIG. 3 and FIG. 7, in this configuration, a plurality of heat transfer tubes 11 in the steam generator 10 are specified in order to identify a damaged portion of the heat transfer tube 11 that is damaged or highly likely to be damaged. The neutron generator 33 and the neutron detection image sensor 34 are arranged to face each other, the switching valve 24 in FIG. 5 is opened, the switching valve 23 is closed, and the He 3 gas in the gas cylinder 22 is opened. However, the gas passes through the first gas supply pipe 26, the second gas supply pipe 28, the third gas supply pipe 30, and the like into the gap 14 between the outer pipe 12 and the inner pipe 13 in the multiple heat transfer pipes 11 of the steam generator 10. Supplied.

  The neutron generator 33 emits neutrons. He3 is an isotope of He and has characteristics of absorbing neutrons and emitting β rays. Neutrons emitted from the neutron generator 33 are absorbed by the He3 gas that has flowed through the gap 14 of the heat transfer tube 11 and leaked from the damaged portion into bubbles. The neutron detection image sensor 34 produces a two-dimensional image of the shadow of neutrons absorbed by the He3 gas flowing through the gap 14 of the heat transfer tube 11 and the He3 gas leaked into bubbles together with neutrons that have passed through the liquid metal sodium Na. To detect.

Normally, He has an absorption coefficient almost zero for neutrons, but He3 has an absorption cross section of 1 × 10 ⁴ burns for thermal neutrons and absorbs a large amount of neutrons. On the other hand, liquid metal sodium Na has an absorption cross section of about 3 burns with respect to thermal neutrons, has little neutron absorption, and neutrons penetrate liquid metal sodium Na. Therefore, by flowing He3 gas through the gap 14 between the outer tube 12 and the inner tube 13 of the heat transfer tube 11, the flowed portion of He3 gas absorbs neutrons and becomes a shadow, and leaks from the damaged portion of the heat transfer tube 11. The He3 gas that has become bubbles is also detected by the neutron detection image sensor 34 as a shadow by absorbing neutrons.

  In the actual two-dimensional image of the neutron detection image sensor 34, as shown in FIG. 8A, the shadow of the structure such as the heat transfer tube 11 that absorbs neutrons is also photographed at the same time. Therefore, the control device 32 that captures a two-dimensional image from the neutron detection image sensor 34 uses the neutron detection image sensor 34 obtained before flowing the He3 gas into the gap 14 between the outer tube 12 and the inner tube 13 of the heat transfer tube 11. A two-dimensional image (FIG. 8B) obtained by a neutron detection image sensor 34 obtained when He3 gas is allowed to flow through the gap 14 between the outer tube 12 and the inner tube 13 of the heat transfer tube 11 with the two-dimensional image (FIG. 8B) as a reference image. 8 (A)) is subjected to difference processing with the reference image to obtain an image (FIG. 8C) displaying only changes when He3 gas is flowed.

  In FIG. 8C, the shadow 35 of the heat transfer tube 11 shown in FIG. 8B is eliminated, and the shadow 36 of the He3 gas flowing in the gap 14 of the heat transfer tube 11 and the damaged portion of the heat transfer tube 11 are removed. Only the shadow 37 of He3 gas leaked as a bubble is displayed. From the position, size, flow direction, and the like of the He3 gas bubble shadow 37, it is possible to detect the position, size, property, and the like of the damaged portion of the heat transfer tube 11.

  Here, the neutron detection image sensor 34 shown in FIGS. 1 to 3 and 7 is preferably an image intensifier for neutron detection with high sensitivity and short imaging time. Since the imaging range of the neutron detection image sensor 34 is generally smaller than the side view region of the steam generator 10, the neutron generator 33 and the neutron detection are used in order to detect a damaged portion in the heat transfer tube 11 in the steam generator 10. It is necessary to move the image sensor 34 in a paired state, and a drive device 38 is provided for this purpose.

  When detecting the damaged part of the heat transfer tube 11, the flow rate of the liquid metal sodium Na is made higher than that during normal operation of the fast breeder reactor so that the bubbles of He3 gas leaked into the liquid metal sodium Na flow vertically upward. Also slow down. Further, in order to efficiently detect the He3 gas leaked into the inner tube 13 of the heat transfer tube 11, water or steam that absorbs neutrons is removed from the inner tube 13, and neutrons pass through the inner tube 13. Keep it easy.

  As shown in FIG. 7 in particular, the drive device 38 includes a rotatable turntable 39 provided around the bottom of the steam generator 10 and a plurality of, for example, four support columns provided upright on the turntable 39. 40, an elevating slider 41 provided on these columns 40 so as to be elevable, a rail 42 spanned between the pair of elevating sliders 41, and a slider 43 movable in the horizontal direction with respect to each rail 42. The neutron generator 33 is installed on one side of the slider 43 and the neutron detection image sensor 34 is installed on the other side. The neutron generator 33 and the neutron detection image sensor 34 are rotated in the horizontal direction of the steam generator 10 by the slider 43, in the vertical direction of the steam generator 10 by the elevating slider 41, and rotated in the horizontal section of the steam generator 10 by the turntable 39. Each of the steam generators 10 is provided so as to be movable, and is positioned close to a position corresponding to the damaged portion of the heat transfer tube 11 in the steam generator 10.

  The neutron generator 33 and the neutron detection image sensor 34 are controlled by the control device 32 so as to move in conjunction with image determination based on the two-dimensional image detected by the neutron detection image sensor 34. That is, since the bubble of He3 gas leaked from the heat transfer tube 11 of the steam generator 10 rises toward the upper part of the steam generator 10, the controller 32 moves the neutron generator 33 and the neutron detection image sensor 34 up and down. The operation of the slider 41 positions the steam generator 10 at, for example, the uppermost position. Next, the control device 32 operates the slider 43 and the turntable 39 to move the neutron generator 33 and the neutron detection image sensor 34 in the horizontal direction, and rotate them in the horizontal section of the steam generator 10, so that the He3 gas Detect bubbles. Further, the control device 32 operates the lift slider 41 from the position to move the neutron generator 33 and the neutron detection image sensor 34 vertically downward, detect the generation location of the He3 gas bubble, and the heat transfer tube 11. Identify the damaged part.

  Since it is configured as described above, the following effects (1) to (4) are achieved according to the present embodiment.

  (1) In the steam generator 10, it is detected that the He gas flowing through the gap 14 between the outer tube 12 and the inner tube 13 of the heat transfer tube 11 has leaked from the damaged portion of the heat transfer tube 11. The detector 18 detects whether or not the heat transfer tube 11 is damaged, and the neutron from the neutron generator 33 flows through the gap 14 between the outer tube 12 and the inner tube 13 and leaks from the damaged portion. When the neutron detection image sensor 34 detects the shadow of the neutron at that time, the damaged portion of the heat transfer tube 11 is specified. From these things, the presence or absence and the damaged part of the heat exchanger tube 11 can be detected with high accuracy and in a short time.

  (2) A large number of heat transfer tubes 11 in the steam generator 10 are grouped into a plurality of first groups A1 to A4 to supply He gas, and a plurality of heat transfer tubes in the first groups A1 to A4 are supplied. 11 is grouped into a plurality of second groups B1 to B16, and He gas is supplied. Similarly, a plurality of heat transfer tubes 11 in each of the (n−1) th groups are connected to a plurality of nth groups. He gas is supplied together for each group, and the gap 14 between the outer tube 12 and the inner tube 13 in the heat transfer tube 11 belonging to the lower group (for example, the groups B1 to B4) connected to the group (for example, the group A1) where leakage is confirmed. By supplying the He gas, the heat transfer tube 11 in which the He gas leaks due to damage is searched. As a result, the efficiency of the search for the damaged heat transfer tube 11 is greatly increased as compared with the case where all the heat transfer tubes 11 of the steam generator 10 are individually checked for damage and searched for the damaged heat transfer tubes 11. Can be improved.

  (3) A two-dimensional image obtained by the neutron detection image sensor 34 obtained before flowing the He3 gas through the gap 14 between the outer tube 12 and the inner tube 13 of the heat transfer tube 11 in the steam generator 10 is used as a reference image, and the heat transfer tube 11 When the He3 gas is caused to flow through the gap 14 between the outer tube 12 and the inner tube 13, a difference process with the reference image is performed on the two-dimensional image obtained by the neutron detection image sensor 34 and the He3 gas is caused to flow. Since only the change can be displayed, the absorption of neutrons by He3 can be detected with high sensitivity, and the damaged portion of the heat transfer tube 11 can be easily identified.

  (4) The driving device 38 including the turntable 39, the lift slider 41, and the slider 43 is controlled by the control device 32, and in conjunction with image determination based on the two-dimensional image detected by the neutron detection image sensor 34, the neutron generator 33 and the neutron detection image sensor 34 are moved. For this reason, this drive device 38 can track the location where the bubbles of He3 gas are generated. Further, the neutron detection image sensor 34 can be brought close to the damaged portion of the heat transfer tube 11, and the damaged portion can be enlarged and photographed by the neutron detection image sensor 34. From these things, the broken part of the heat exchanger tube 11 can be pinpointed efficiently.

[B] Second embodiment (FIGS. 9 and 10)
FIG. 9 shows an example of a gas leakage detector of the heat transfer tube breakage detection device in the steam generator of the fast breeder reactor to which the second embodiment of the heat transfer tube breakage detection device of the heat exchanger according to the present invention is applied. (A) is a block diagram of a gas leak 1st detector, (B) is a block diagram of a gas leak 2nd detector. FIG. 10 shows another example of the gas leakage detector of the heat transfer tube breakage detection device in the steam generator of the fast breeder reactor to which the second embodiment of the heat transfer tube breakage device of the heat exchanger according to the present invention is applied. (A) is a block diagram of a gas leak 1st detector, (B) is a block diagram of a gas leak 2nd detector. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  In the present embodiment, He gas is caused to flow through the gap 14 between the outer tube 12 and the inner tube 13 in the heat transfer tube 11 of the steam generator 10 during the operation of the fast breeder reactor, and the gas leakage first detector 16A and the gas leakage second After the breakage of the heat transfer tube 11 is confirmed using the detector 18A, or the gas leak first detector 16B and the gas leak second detector 18B, and the fast breeder reactor is stopped, the He3 gas enters the gap 14 of the heat transfer tube 11. And using the gas leak first detector 16A and the gas leak second detector 18A, or the gas leak first detector 16B and the gas leak second detector 18B, search for which heat transfer tube 11 is damaged. Is. Here, the gas leak first detector 16A and the gas leak second detector 18A have the radiation detector 45 (FIG. 9) in addition to the He concentration detector (not shown), and the gas leak first detector. 16B and the gas leakage second detector 18B include a neutron source 46 and a neutron detector 47 (FIG. 10) in addition to a He concentration detector (not shown).

  To switch from He gas to He3 gas, the switching valve 24 shown in FIG. 5 is opened and the switching valve 23 is closed so that the He3 gas in the gas cylinder 22 is supplied to the first gas supply pipe 26 and the second gas supply. The gas is supplied to the gap 14 between the outer pipe 12 and the inner pipe 13 in the multiple heat transfer pipes 11 of the steam generator 10 through the pipe 28, the third gas supply pipe 30, and the like.

  As shown in FIGS. 1 and 9, the first gas leakage detector 16 </ b> A provided in the outflow pipe 15 of the liquid metal sodium Na in the steam generator 10 is liquid metal sodium from the damaged portion of the outer pipe 12 of the heat transfer pipe 11. The radiation detection unit 45 detects β rays emitted by He3 gas leaked into Na. Further, the gas leakage second detector 18A provided in the outflow pipe 17 from which the steam W flows out in the steam generator 10 releases He3 gas leaked into the steam W from the damaged portion of the inner pipe 13 of the heat transfer pipe 11. The radiation detection unit 45 that detects β rays is included. These radiation detection units 45 detect β rays to detect the concentration of He3 leaked into the liquid metal sodium Na or the vapor W.

  As another embodiment, as shown in FIGS. 1 and 10, the gas leakage first detector 16 </ b> B provided in the outflow pipe 15 of the liquid metal sodium Na in the steam generator 10 includes the neutron source 46 and the neutron detection. When the neutrons emitted from the neutron source 46 are absorbed by the He3 gas leaked into the liquid metal sodium Na from the damaged portion of the outer tube 12 of the heat transfer tube 11, the remaining neutrons are detected by the neutron detector 47. Detects the concentration of He3 in the liquid metal sodium Na. The gas leakage second detector 18B provided in the steam W outflow pipe 17 in the steam generator 10 includes a neutron source 46 and a neutron detector 47, and the steam W from the damaged portion of the inner pipe 13 of the heat transfer tube 11 is provided. When neutrons emitted from the neutron source 46 are absorbed by the He3 gas leaked into the neutron detector 47, the neutron detector 47 detects the remaining neutrons, thereby detecting the concentration of He3 in the vapor W.

  Therefore, according to the present embodiment, in addition to the same effects (1) to (4) as in the first embodiment, the following effect (5) is achieved.

  (5) The gas leakage first detector 16A and the gas leakage second detector 18A detect the β-rays emitted from the He3 gas to detect the concentration of He3, and the gas leakage first detector 16B and the gas leakage. The second detector 18B detects the concentration of He3 based on the neutrons absorbed by the He3 gas. For this reason, in this embodiment, compared with the case where the gas leak first detector 16 and the gas leak second detector 18 of the above embodiment detect the He concentration, the detection sensitivity of the He3 concentration detection is improved. Can do. As a result, among the heat transfer tubes 11 in the steam generator 10, the gas leakage first detector 16A and the gas leakage second detector 18A, or the gas leakage first detector 16B and the gas leakage second detector 18B are used. The search for the damaged heat transfer tube 11 can be realized reliably and easily.

[C] Third embodiment (FIG. 11)
FIG. 11 shows an approximate position of a broken portion in the heat transfer tube breakage detecting apparatus in the steam generator of the fast breeder reactor to which the third embodiment of the heat exchanger tube breakage detecting apparatus of the heat exchanger according to the present invention is applied. (A) is a schematic conduit diagram of a heat transfer tube in the steam generator, and (B) is a timing chart at the time of switching to He3 gas and when the concentration of He3 is detected. In the third embodiment, the same parts as those in the first and second embodiments are denoted by the same reference numerals, and the description is simplified or omitted.

  Also in the third embodiment, when searching which heat transfer tube 11 in the steam generator 10 (FIG. 1) is broken, the He into the gap 14 between the outer tube 12 and the inner tube 13 of the heat transfer tube 11 is obtained. He3 gas is supplied instead of the gas, and the concentration of He3 is detected by the gas leakage first detector 16A and the gas leakage second detector 18A provided with the radiation detection unit 45 (FIG. 9), or by the neutron source 46 and the neutron detection. The gas leakage first detector 16B and the gas leakage second detector 18B provided with the detector 47 (FIG. 10) respectively detect the same as in the second embodiment. Further, in the present embodiment, the control device 32 determines the approximate position of the damaged portion of the damaged heat transfer tube 11 searched for from the first gas leakage detectors 16A and 16B or the second gas leakage detector 18A from the time of switching of the He3 gas. , 18B, based on the time until the He3 concentration detection time.

  That is, as shown in FIG. 11, the control device 32 causes the He3 gas in the gas cylinder 22 to pass through the first gas supply pipe 16, the second gas supply pipe 28, and the like in the multiple heat transfer pipes 11 of the steam generator 10. The switching valve 24 is instantaneously opened to the gap 14 between the pipe 12 and the inner pipe 13, and the switching valve 23 is instantaneously closed to switch it in a pulsed manner. A symbol E in FIG. 11B indicates a waveform when the He3 gas flows in a pulse shape, and this time is t0. Next, the control device 32 determines whether the gas leak first detector 16A, 16B or the gas leak second detector 18A, 18B, for example, the gas leak first detector 16A, 16B is He3 in the liquid metal sodium Na of the steam generator 10. The time points t1 and t2 at which the change in density (waveforms F1 and F2 described later) are detected are measured. A symbol F1 in FIG. 11B is a waveform indicating a change in the concentration of He3 detected by the first gas leak detectors 16A and 16B when the downstream portion P of the heat transfer tube 11 is damaged. Reference symbol F2 is a waveform showing a change in the concentration of He3 detected by the first gas leak detectors 16A and 16B when the upstream portion Q of the heat transfer tube 11 is broken.

  In general, in the steam generator 10, the flow rate of the He 3 gas flowing through the gaps 14 between the outer tube 12 and the inner tube 13 of the multiple heat transfer tubes 11 is faster than the flow rate of the liquid metal sodium Na flowing in the steam generator 10. When the downstream portion P of the heat transfer tube 11 in the steam generator 10 is broken, the time T1 from the switching time t0 to He3 gas to the time t1 when the concentration change of He3 is detected by the gas leakage first detectors 16A and 16B. Is a short time. On the other hand, when the upstream portion Q of the heat transfer tube 11 in the steam generator 10 is broken, a change in the concentration of He3 is detected by the gas leakage first detectors 16A and 16B from the switching time t0 to the He3 gas. Time T2 until time t2 is long because the leaked He3 gas rides on the flow of liquid metal sodium Na having a low flow rate.

  Accordingly, the control device 32 detects the first gas leakage from the position of the plurality of breakage points in the heat transfer tube 11 in the steam generator 10 and when the He3 gas leaks from each breakage point from the time of switching to the He3 gas. The relationship with the time to detect the concentration change of He3 by the devices 16A and 16B is measured in advance by a test or the like and stored as a calibration value. Then, the control device 32 actually obtains the times T1 and T2 from the time t0 when switching to He3 gas to the time t1 and t2 when the concentration change of He3 is detected by the gas leakage first detectors 16A and 16B. By comparing T1 and T2 with the calibration values obtained in advance, it is possible to detect the approximate position of the damaged portion of the heat transfer tube 11 from which the He3 gas has leaked.

  In the present embodiment, the case where the gas leakage first detectors 16A and 16B detect a change in the concentration of He3 in the liquid metal sodium Na has been described. However, the gap between the outer tube 12 and the inner tube 13 of the heat transfer tube 11 is described. When He3 gas leaks into water or steam W having a flow rate slower than the flow rate of He3 gas flowing through 14, the concentration change of He3 in the water or steam W flowing inside the inner pipe 13 is detected as a second gas leak. The same applies to the case of detection by the devices 18A and 18B.

  Therefore, according to the present embodiment, in addition to the same effects (1) to (5) as in the first and second embodiments, the following effect (6) is achieved.

  (6) Times T1, T2,... From the time t0 when switching to He3 gas to the time points t1, t2,..., The detection of He3 concentration change by the gas leak first detectors 16A, 16B or the gas leak second detectors 18A, 18B. Since the approximate position of the damaged portion in the heat transfer tube 11 in the steam generator 10 is detected based on the above, the damaged portion of the heat transfer tube 11 to be identified later using the neutron generator 33 and the neutron detection image sensor 34 is identified. Can be implemented quickly and efficiently.

The schematic block diagram which shows the heat exchanger tube breakage detection apparatus in the steam generator of the fast breeder reactor to which 1st Embodiment in the heat exchanger tube breakage detection apparatus of the heat exchanger which concerns on this invention was applied. II arrow line view of FIG. Fig. 3 arrow view of Fig. 2 FIG. 4 is a side view of the heat transfer tube (double heat transfer tube) of FIG. FIG. 3 is a pipeline diagram showing a gas supply line for supplying a detection gas for detecting breakage of the heat transfer tube to the multiple heat transfer tubes in FIG. 2. It is a horizontal cross section of the multiple heat exchanger tubes in FIG. 2, (A) is explanatory drawing which shows each 1st group A1-A4 of a heat exchanger tube, (B) is 2nd each group B1 of heat exchanger tubes. Explanatory drawing which shows B4, (C) is explanatory drawing which shows each 3rd group C1, C2 of a heat exchanger tube, (D) is explanatory drawing which shows the 3rd group C1 of FIG.6 (C). The perspective view which shows the heat exchanger tube breakage detection apparatus of FIG. FIG. 1 shows a photographed image taken by the neutron detection image sensor of FIG. 1, (A) is a photographed image when He3 gas is flowed, (B) is a photographed image before flowing He3 gas, and (C) is a photograph of (A). The image figure when the image of (B) is subtracted from the image. An example of the gas leakage detector of the heat transfer tube breakage detection device in the steam generator of the fast breeder reactor to which the second embodiment of the heat transfer tube breakage detection device of the heat exchanger according to the present invention is applied is shown in (A). Is a block diagram of a gas leak first detector, and (B) is a block diagram of a gas leak second detector. The other example of the gas leak detector of the heat exchanger tube breakage detector in the steam generator of the fast breeder reactor to which the second embodiment of the heat exchanger tube breaker of the heat exchanger according to the present invention is applied is shown in (A ) Is a configuration diagram of a gas leakage first detector, and (B) is a configuration diagram of a gas leakage second detector. Explanatory drawing for calculating | requiring the approximate position of a failure part in the heat exchanger tube breakage detection apparatus in the steam generator of a fast breeder reactor to which the third embodiment of the heat exchanger tube breakage detection apparatus of the heat exchanger according to the present invention is applied (A) is a schematic conduit diagram of a heat transfer tube in the steam generator, and (B) is a timing chart of the switching time to He3 gas and the concentration detection time of He3.

Explanation of symbols

10 Steam generator (heat exchanger)
11 Heat transfer tube 12 Outer tube 13 Inner tube 14 Gap 16, 16A, 16B Gas leakage first detector 18, 18A, 18B Gas leakage second detector 26 First gas supply tube 28 Second gas supply tube 30 Third gas supply Tubes 26A, 28A, 30A Flow rate adjusting valve 32 Control device 33 Neutron generator 34 Neutron detection image sensor 37 Shadow 38 Drive device 45 Radiation detector 46 Neutron source 47 Neutron detector Na Liquid metal sodium (first fluid)
W Water or steam (second fluid)
A1 to A4 First group B1 to B4 Second group C1 and C2 Third group t0 Switching point to He3 gas t1 and t2 He3 concentration change detection time

Claims (15)

Each of the multiple heat transfer tubes is a double heat transfer tube including an outer tube and an inner tube, and heat exchange is performed between the first fluid flowing outside the outer tube and the second fluid flowing inside the inner tube. A heat exchanger for performing
A gas leakage detector for detecting that the first detection gas flowing through the gap between the outer tube and the inner tube leaks from the damaged portion of the heat transfer tube in order to confirm whether or not the heat transfer tube is damaged;
In order to identify the damaged portion of the heat transfer tube, it has a neutron generator and a neutron detection image sensor arranged to face each other across the heat transfer tube,
Neutrons emitted from the neutron generator are absorbed by the second detection gas leaked from the damaged portion through the gap between the outer tube and the inner tube, and the neutron detection image sensor detects the shadow of the neutron at that time. A heat transfer tube breakage detection device for a heat exchanger, wherein the heat transfer tube breakage detection device is detected as a two-dimensional image. A gas supply line that supplies the first or second detection gas to the gaps between the outer tube and the inner tube in the plurality of heat transfer tubes,
A plurality of first heat supply tubes, each of which is grouped into a plurality of first groups, to supply the first or second detection gas, and a plurality of first gas supply tubes each having a flow control valve;
The plurality of heat transfer tubes in each of the first groups are grouped into a plurality of second groups to supply the first or second detection gas, and each of a plurality of second tubes each having a flow control valve. A second gas supply pipe,
Similarly, a plurality of the heat transfer tubes in each of the (n−1) th groups are grouped into a plurality of n (n: natural number) th groups to supply the first or second detection gas, A plurality of nth gas supply pipes each having a flow control valve,
By operating the flow rate adjusting valves of the first to nth gas supply pipes of such a tree structure in conjunction with the signal of the gas leak detector, the lower order connected to the group that has detected the leak The first or second detection gas is supplied to a gap between the outer tube and the inner tube in the group of heat transfer tubes, and the heat transfer tube in which the first or second detection gas leaks due to breakage is searched. The heat exchanger tube breakage detecting device for a heat exchanger according to claim 1, wherein A second detection gas that emits radiation flows in a gap between the outer tube and the inner tube of the heat transfer tube,
The gas leakage detector includes a radiation detection unit that detects radiation from the second detection gas leaked from the damaged portion of the outer tube and the inner tube, and the leakage of the second detection gas leaked by detection of the radiation. The heat exchanger tube breakage detecting device for a heat exchanger according to claim 1, wherein the device is configured to detect a concentration. A second detection gas that absorbs neutrons flows in a gap between the outer tube and the inner tube of the heat transfer tube,
The gas leakage detector includes a neutron source and a neutron detection unit, and the neutron detection unit detects a remaining neutron when the neutron emitted from the neutron source is absorbed by the second detection gas. 2. The heat exchanger tube breakage detecting device for a heat exchanger according to claim 1, wherein the second detection gas concentration is detected. When the second detection gas flows from the first detection gas to the gap between the outer tube and the inner tube of the heat transfer tube in a pulsed manner and the second detection gas is detected by the gas leakage detector from this switching time 5 or 4, wherein the approximate position of the damaged portion of the heat transfer tube where the second detection gas has leaked is obtained by comparing the time until the calibration value obtained in advance. The heat exchanger tube breakage detection device of the described heat exchanger. The heat transfer tube breakage detection device for a heat exchanger according to claim 1, wherein the neutron detection image sensor is an image intensifier for neutron detection with high sensitivity and short imaging time. A two-dimensional image obtained by a neutron detection image sensor obtained before flowing the second detection gas through the gap between the outer tube and the inner tube of the heat transfer tube is used as a reference image, and the second detection is performed in the gap between the outer tube and the inner tube. Difference processing with the reference image is performed on the two-dimensional image obtained by the neutron detection image sensor obtained when the gas is flowed, and only changes when the second detection gas is flowed can be displayed. The heat exchanger tube breakage detecting device for a heat exchanger according to claim 1. The neutron generator and the neutron detection image sensor can be moved by a driving device in at least one of a horizontal direction of the heat exchanger, a vertical direction of the heat exchanger, and a rotation direction in a horizontal section of the heat exchanger. The heat exchanger tube breakage detecting device for a heat exchanger according to claim 1, wherein the heat exchanger tube breakage detecting device for a heat exchanger according to claim 1, wherein the heat exchanger tube breakage detecting device is provided at a position corresponding to a breakage point in the heat exchanger tube of the heat exchanger. 9. The drive device according to claim 8, wherein the drive device is configured to move the neutron generation device and the neutron detection image sensor in conjunction with image determination based on a two-dimensional image detected by a neutron detection image sensor. Heat exchanger tube breakage detector. The first detection gas is He gas, and the second detection gas is an isotope of He gas, and emits beta rays as radiation, and is He3 gas capable of absorbing neutrons. The heat exchanger tube breakage detection device for a heat exchanger according to claim 1. The heat exchanger tube of the heat exchanger according to claim 1, wherein the heat exchanger is a steam generator of a fast breeder reactor, the first fluid is liquid metal sodium, and the second fluid is water. Detection device. Each of the multiple heat transfer tubes is a double heat transfer tube including an outer tube and an inner tube, and heat exchange is performed between the first fluid flowing outside the outer tube and the second fluid flowing inside the inner tube. A heat exchanger for performing
The gas leakage detector detects that the first detection gas flowing through the gap between the outer tube and the inner tube has leaked from the damaged portion of the heat transfer tube, thereby confirming whether the heat transfer tube is damaged,
When the heat transfer tube is damaged, neutrons emitted from the neutron generator are absorbed by the second detection gas leaked from the damaged portion through the gap between the outer tube and the inner tube, The neutron shadow is detected as a two-dimensional image by a neutron detection image sensor arranged opposite to the neutron generator and the heat transfer tube to identify the damaged portion of the heat transfer tube. Heat exchanger tube breakage detection method for heat exchangers. When supplying the first or second detection gas to the gap between the outer tube and the inner tube of the multiple heat transfer tubes,
A plurality of the heat transfer tubes are grouped into a plurality of first groups to supply the first or second detection gas,
A plurality of the heat transfer tubes in the first group, which have been confirmed to leak, are grouped into a plurality of second groups, and the first or second detection gas is supplied,
Similarly, a plurality of the heat transfer tubes in the (n-1) th group whose leakage has been confirmed are grouped into a plurality of n (n: natural number) th groups, and the first or second detection gas is collected. Supply
The first or second detection gas is damaged by supplying the first or second detection gas to the gap between the outer tube and the inner tube in the heat transfer tube of the lower group connected to the group in which leakage has been detected. The heat transfer tube breakage detection method for a heat exchanger according to claim 12, wherein the heat transfer tube from which gas has leaked is searched. 13. The heat exchanger according to claim 12, wherein the first detection gas is He gas, and the second detection gas is He 3 gas that is an isotope of He gas and can absorb neutrons. Heat transfer tube breakage detection method. The heat exchanger tube breakage of the heat exchanger according to claim 12, wherein the heat exchanger is a steam generator of a fast breeder reactor, the first fluid is liquid metal sodium, and the second fluid is water. Detection method.

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