JP2008191069A - Reflector control type fast reactor, and neutron detector installation method and operation method for same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly economical reflector control type fast reactor, capable of reducing influence of signal fluctuation in a neutron detector accompanying the movement of a neutron reflector to reduce an detection error, and capable of giving the lowest estimate for a thermal output error to control nuclear reactor power. <P>SOLUTION: In this neutron detector installation method for the reflector control type fast reactor 3 for installing the neutron detectors 31A, 31B in an outside of a reactor vessel 1, in the reflector control type fast reactor 30 for controlling a reactivity of a reactor core 2 by moving the neutron reflector 9 installed outside the reactor core stored in the reactor vessel along an axial direction of the reactor core, and by regulating a leakage of a neutron from the reactor core to control the reactivity of the reactor core, the plurality of neutron detectors is installed along the axial direction of the reactor core, the neutron detector 31A thereof is installed within a moving range X of the neutron reflector 9, and the neutron detector 31B is installed outside the moving range X of the neutron reflector, so as to summed up signals from the neutron detectors installed respectively within the moving range and outside the moving range. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a neutron detector installation method and operation method for a reflector control type fast reactor that controls the reactivity of a core by moving a neutron reflector, and a reflector control type fast reactor.

  For example, the conventional general configuration of the reflector control type fast reactor described in Patent Documents 1 and 2 will be described with reference to FIGS. 10 schematically shows a conventional reflector-controlled fast reactor only in the right half from the center, FIG. 11 shows a diametrical cross section of the fast reactor in FIG. 10, and FIG. 12 shows the fuel assembly in FIG. Show.

  As shown in FIG. 10, a reactor core 2 is located in the center of the reactor vessel 1, and a neutron shield 3 is disposed at a position surrounding the reactor core 2, and a liquid metal such as sodium is used. The coolant 4 is filled.

  As shown in FIG. 11, the core 2 is composed of, for example, 18 hexagonal fuel assemblies 5. At the center, the reactor 2 is used for controlling the reactivity of the core 2. The channel 6 is arranged and surrounded by the core barrel 7.

  A partition wall 8 that divides the flow path of the coolant 4 at a predetermined interval is disposed outside the core barrel 7, and the space provided between the core barrel 7 and the partition wall 8 operates the core 2. A moving region 10 of the neutron reflector 9 used in the above is formed.

  Here, the coolant 4 flows from the lower side to the upper side of the partition wall 8 and enters the core 2 in the middle thereof, and the temperature rises by taking away the heat generated by the fission. The coolant 4 whose temperature has risen flows into the interior of an intermediate heat exchanger (not shown), and after exchanging heat with the secondary coolant, it flows out downward from the intermediate heat exchanger. The cooled coolant 4 after the heat exchange passes through the outside of the partition wall 8 and goes around the lower part of the core 2 and is again introduced into the core 2.

  The neutron shield 3 limits the amount of neutron irradiation of the reactor vessel 1 to a predetermined value or less over the entire life of the reflector control type fast reactor, and is disposed between the reactor vessel 1 and the partition wall 8. A plurality of neutron shielding rods 11 are used.

As a configuration of the neutron shield 3, in addition to a structure made of stainless steel or the like, a pin containing B ₄ C ceramic containing boron having a large neutron absorption capability is arranged, or a metal such as hafnium or tantalum or These compounds can be included.

  Further, the ability of the neutron reflector 9 to control the reactivity of the reactor core 2 can be increased by disposing a neutron absorber or neutron transmitting material inferior to the coolant in the upper region 24 of the neutron reflector 9. (For example, refer to Patent Document 3). Reference numeral 12 denotes a guard vessel surrounding the reactor vessel 1.

  Furthermore, a neutron detector 25 is installed outside the guard vessel 12. The signal of the neutron detector 25, the data of the thermal output measuring device, etc. are processed, and the reflector controlled fast reactor is operated with the output (nuclear output) controlled.

  In the fuel assembly 5, for example, as shown in FIG. 12, a number of fuel pins 14 are regularly arranged inside a stainless steel hexagonal trumpet tube 13, and neutron shielding is provided above and below the trumpet tube 13. It is comprised by arrange | positioning the bodies 15a and 15b.

  In the figure, one of a large number of fuel pins 14 is taken out, and this fuel pin 14 is provided with a fuel portion 14a and a plenum portion 14b for containing a gas component generated by nuclear fission. ing. The fuel pin 14 promotes the mixing of the coolant 4 by wire wrap or a grid (not shown), and is fixed to the trumpet tube 13 at the lower end plug portion. The fuel assembly 5 is inserted into and fixed to the core support 17 through a small-diameter entrance nozzle 16 and is provided with a coolant inlet 18 and a coolant outlet 19.

  In the moving region 10 between the core barrel 7 and the partition wall 8 shown in FIG. 11, a neutron reflector 9 is arranged as shown in FIG. The neutron reflector 9 is suspended and supported at the lower end of the drive rod 20. The drive rod 20 extends upward through a shielding plug 21 that closes the upper end opening of the reactor vessel 1, and the upper surface of the shielding plug 21. Is moved in the vertical direction, that is, in the axial direction of the core 2.

  That is, as the driving device 22 is driven, the neutron reflector 9 passes through the driving rod 20 in the moving region 10 between the core barrel 7 and the bulkhead 8 along the core 2 in the vertical direction (of the core 2 It is configured to move in the axial direction). A space between the liquid level 4a of the coolant 4 and the shielding plug 21 is a cover gas space 23 filled with a cover gas.

  As a result, the neutron reflector 9 is moved in the axial direction of the core 2 via the driving device 22 to adjust the leakage of neutrons from the core 2, thereby controlling the reactivity of the core 2. This reactivity control is performed in order to compensate for the decrease in the core reactivity due to the start-stop of the core and the combustion of fuel.

As an example of the specifications of the core 2 in the reflector-controlled fast reactor, as shown in Table 1, the thermal output is about 120 MWt, the core diameter is about 130 cm, the core height is 200 cm, and the enriched uranium metal alloy U-Zr is used as the fuel. Some cores operate for about 30 years without refueling, and a 200-cm long neutron reflector is pulled up at a constant speed to compensate for changes in reactivity due to fuel combustion.

  FIG. 14 shows the relative value of the neutron count rate detected by the neutron detector 25 installed on the side of the core 2 at this time. In this result, the neutron count rate by the neutron detector 25 installed on the side of the core 2 decreases as the operation of the reactor proceeds, and at the end of combustion after 30 years is about one digit compared with the initial stage of combustion. It tends to be smaller.

  In the reflector controlled fast reactor shown in FIG. 10, the axial movement of the neutron reflector 9 during the operation of the reactor, as shown in FIG. 13, raises the neutron reflector 9 at the initial stage of combustion to make the core 2 critical, After that, the neutron reflector 9 is lowered and operated at a constant output, and the decrease in reactivity due to the combustion of the core 2 is compensated by the rise of the neutron reflector 9. After 30 years, the neutron reflector 9 covers the entire core 2. Become. The change tendency shown in FIG. 14 of the neutron count rate detected by the neutron detector 25 is due to the fact that the neutron flow is blocked from the neutron detector 25 as the neutron reflector 9 moves in the axial direction. .

  On the other hand, FIG. 16 shows the neutron count rate detected by the neutron detector 25 when the neutron detector 25 is installed at the bottom of the core 2 as shown in FIG. In this case, the neutron count rate increases as the operation of the reactor proceeds, contrary to the neutron count rate by the neutron detector 25 installed on the side of the core 2, and at the end of combustion after 30 years, the initial stage of combustion It tends to be about an order of magnitude larger than. This tendency is due to the fact that neutrons flow into the neutron detector 25 as the neutron reflector 9 moves.

As described above, the neutron count rate detected by the neutron detector 25 installed on the side or bottom of the core 2 is about 1 each due to the influence of the axial movement of the neutron reflector 9 accompanying the operation of the reactor. There are digit fluctuations. Therefore, when controlling the reactor power (nuclear power) using the neutron counting rate detected by these neutron detectors 25, the detection error of the neutron counting rate becomes large. It is necessary to control so as not to cause an excessive output by largely estimating an error of the heat output measured by the output measuring device. As a result, the operation is performed at an output (nuclear output) lower than the rated output, resulting in a reflector-controlled fast reactor with low economic efficiency.
JP-A-4-81694 JP-A-4-194780 JP-A-6-51082

  In a conventional fast reactor, a neutron detector is placed at a position outside the reactor where the neutron flux is not distorted by operating a control rod, and the output is monitored by monitoring the neutron flux. However, in the reflector control type fast reactor as described above, the neutron count rate detected by the neutron detector 25 installed on the side or bottom of the core 2 is the movement of the neutron reflector 9 accompanying the operation of the fast reactor. In spite of this, there is a fluctuation of about 1 digit during operation even though the output has not changed. That is, the proportional relationship between the output of the core 2 and the neutron flux detected by the neutron detector 25 changes. In the conventional fast reactor, the neutron count rate detected by the neutron detector fluctuates by about 20%, and this is allowed as a heat output error. However, in the reflector control type fast reactor described above, when the neutron count rate detected by the neutron detector 25 fluctuates by about one digit, this is allowed as a thermal output error. You will lose.

  The object of the present invention has been made in consideration of the above-mentioned circumstances. The influence of fluctuations in the signal of the neutron detector accompanying the movement of the neutron reflector is reduced to reduce the detection error, and the heat output error is reduced. Provided is a reflector control system fast reactor neutron detector installation method and operation method, and a reflector control system fast reactor that can control the reactor power by estimation and thereby realize a highly economical reflector control system fast reactor. There is.

  In the reflector control method fast reactor neutron detector installation method according to the present invention, the neutron reflector installed outside the core housed in the reactor vessel is moved in the axial direction of the core, A reflector-controlled fast reactor that controls the reactivity of the core by adjusting leakage of neutrons, and a neutron detector installed in a reflector-controlled fast reactor in which a neutron detector is installed outside the reactor vessel In the method, a plurality of the neutron detectors are installed in the axial direction of the core, at least one of these neutron detectors is installed within a moving range of the neutron reflector, and at least one of the neutron detectors is installed. It is installed outside the moving range of the neutron reflector, and the signals of the neutron detectors installed inside and outside the moving range are summed up.

  Also, the operating method of the reflector control type fast reactor according to the present invention is the detection signal from the neutron detector installed using the neutron detector installation method of the reflector control type fast reactor according to the present invention. Combined with a signal that has a function to monitor the reactor state other than the signal, the signal processing is performed to complement the error of each signal accompanying the movement of the neutron reflector, and the reactor output is controlled. It is.

  Furthermore, the reflector control type fast reactor according to the present invention moves a neutron reflector installed outside the core accommodated in the reactor vessel in the axial direction of the core, and leaks neutrons from the core. In the reflector control type fast reactor that controls the reactivity of the core by adjusting the plurality of neutron detectors in the axial direction of the core outside the reactor vessel, at least one of these A neutron detector is installed within the moving range of the neutron reflector, and at least one of the neutron detectors is installed outside the moving range of the neutron reflector, and is installed inside and outside these moving ranges, respectively. The neutron detector signals are combined and processed.

  According to the reflector control type fast reactor installation method and reflector control type fast reactor according to the present invention, at least one of the neutron detectors installed in the axial direction of the core outside the reactor vessel. Two neutron detectors are installed within the moving range of the neutron reflector, and at least one neutron detector is installed outside the moving range of the neutron reflector, and the neutron detectors installed inside and outside these moving ranges, respectively. The signal of the instrument is summed up. For this reason, the neutron reflector moves to compensate for the combustion reactivity associated with the operation of the reactor, and the movement of this neutron reflector fluctuates the signals of the neutron detectors installed inside and outside this moving range. However, by adding these signals together, it is possible to reduce the influence of fluctuation of each signal and reduce the detection error. As a result, it is possible to estimate the error of the thermal output measured by the thermal output measuring device small, and the reactor can be controlled with the rated output, so that a highly economical reflector control type fast reactor can be realized.

  Further, according to the operation method of the reflector control type fast reactor according to the present invention, the detection signal from the neutron detector is combined with a signal having a function of monitoring the reactor state other than the detection signal, and the neutron reflector Since the signal output is controlled to compensate for the error of each signal that accompanies the movement and the output of the reactor is controlled, the error of each signal is reduced. A high-speed reflector control system fast reactor can be realized.

  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 4)
FIG. 1A is a schematic view of a reflector control type fast reactor in which the first embodiment of the neutron detector installation method for a reflector control type fast reactor according to the present invention is cut in the axial direction. It is a half section and (B) is a figure showing the movement position of the neutron reflector of Drawing 1 (A). FIG. 2 is a graph showing the neutron count rate detected by the neutron detector of FIG. In the first embodiment, the same parts as those in the background art are denoted by the same reference numerals, and the description is simplified or omitted.

  In the reflector control type fast reactor 30 shown in FIG. 1 (A), neutron reflection is performed outside the reactor core 2 housed in the reactor vessel 1 and immersed in the liquid metal coolant, and inside the reactor vessel 1. A body 9 is installed. The reactivity of the core 2 is controlled by adjusting the leakage of neutrons from the core 2 by moving the neutron reflector 9 in the axial direction of the core 2.

  In such a reflector control type fast reactor 30, a plurality of neutron detectors for detecting leakage of neutrons from the core 2 are installed in the axial direction of the core 2. Among these, at least one neutron detector (one neutron detector 31 </ b> A in the present embodiment) is installed on the side of the reactor vessel 1, and at least one neutron detector (this In the embodiment, one neutron detector 31B) is installed.

  By the way, as shown in FIG. 1B, the neutron reflector 9 is located at the lower part of the core 2 at the initial stage of operation (initial stage of combustion) and burns the fuel below the core 2, and then the reactivity of the core 2 is measured. In order to compensate for the decrease, the fuel gradually rises to burn the fuel above the core 2 sequentially. Thus, the neutron reflector 9 moves in the axial direction of the core 2 over the entire operation period of the reflector control type fast reactor 30. A neutron detector 31A is installed within the movement range X of the neutron reflector 9, and a neutron detector 31B is installed outside the movement range.

  In these neutron detectors 31A and 31B, neutrons that are directly transmitted from the core 2, and vertically or obliquely transmitted from the core 2, are provided in the inside and outside of the reactor vessel 1 in regions with a relatively low material density. Neutrons that indirectly reach through the gap are detected. Since these neutrons contribute to the neutron detectors 31A and 31B with the movement of the neutron reflector 9 during the operation of the reflector controlled fast reactor 30, the neutron detectors 31A and 31B detect the neutron counts to be detected. The rate varies, for example, by about 3% annually.

  In the neutron detector 31A, as shown by the one-dot chain line A in FIG. 2 and FIG. 14, in the initial stage of operation, there are relatively many neutrons that pass through the core 2 and directly reach the neutron detector 31A. The detected neutron count rate is high at the beginning of operation, but gradually decreases as the neutron reflector 9 rises. Further, in the neutron detector 31B, as shown by a broken line B in FIG. 2, the neutron reflector 9 passes through the core 2 and reaches the neutron detector 31B directly at the end of operation (end of combustion) where the neutron reflector 9 is at the highest position. Since the number of neutrons is relatively large, the neutron count rate detected by the neutron detector 31B is small at the beginning of operation, but gradually increases as the neutron reflector 9 rises.

  Therefore, the detection signals from the neutron detectors 31A and 31B are added together to obtain a combined processing signal. As a result, as shown by the solid line C in FIG. 2, the combined processing signals are converted from the detected signals from the neutron detectors 31 </ b> A and 31 </ b> B in accordance with the movement of the neutron reflector 9 in FIG. 2. Even if it fluctuates like this, the influence of this fluctuation | variation can be made small and the detection error of the neutron count rate by the neutron detectors 31A and 31B can be reduced.

  Therefore, according to the present embodiment, the following effects can be obtained.

  Of the neutron detectors 31A and 31B installed in the axial direction of the core 2 in the reactor vessel 1, the neutron detector 31A is installed in the moving range X of the neutron reflector 9, and the neutron detector 31B is reflected by neutron reflection. It installs outside the movement range X of the body 9, and adds the detection signals regarding the neutron count rates of the neutron detectors 31A and 31B installed outside the movement range X, respectively. For this reason, the neutron reflector 9 moves to compensate for the combustion reactivity associated with the reactor operation, and the neutron detectors 31A respectively installed inside and outside the moving range X by the movement of the neutron reflector 9; Even if the detection signal of 31B fluctuates, the influence of fluctuation of each detection signal can be reduced by adding these detection signals, and the detection error related to the neutron count rate detected by the neutron detectors 31A and 31B can be reduced. Can be reduced. Thereby, it becomes possible to estimate the error of the heat output measured by the heat output measuring device (not shown) small, and the core 2 can be controlled with the rated output, so that the highly economical reflector control type fast reactor 30 can be realized. .

  The thermal output measuring device measures the thermal output from the temperature difference between the outlet and the inlet of the core 2 in the coolant. Further, the neutron detector 31B installed outside the moving range X of the neutron reflector 9 is not limited to being installed at the lower part of the core 2, but may be installed at the upper part of the core 2 as shown in FIG. Alternatively, it may be installed at the bottom of the core 2 as shown in FIG. Also in these cases, the same effect as the above (1) can be obtained by adding together with the detection signal by the neutron detector 31A installed in the movement range X of the neutron reflector 9.

[B] Second embodiment (FIGS. 5 and 6)
5A is a schematic diagram showing a reflector control type fast reactor in which the second embodiment of the neutron detector installation method of the reflector control type fast reactor according to the present invention is cut in the axial direction. It is sectional drawing, (B) is a figure which shows the movement position of the neutron reflector of FIG. 5 (A). FIG. 6 is a cross-sectional view showing the reflector control type fast reactor of FIG. In the second embodiment, the same parts as those in the first embodiment and the background art are denoted by the same reference numerals, and the description will be simplified or omitted.

  In the reflector control type fast reactor 40 of the present embodiment, the neutron reflector 41 is divided into a plurality of, for example, six sectors 42 in the circumferential direction, and each sector 42 is independently controlled by the driving device 22. It is configured to move in the axial direction of the core 2 through the rod 20 (both see FIG. 10).

  In such a reflector control type fast reactor 40, a plurality of neutron detectors are installed along the axial direction of the core 2 at positions facing each sector 42. That is, for each sector 42, at least one neutron detector (in the present embodiment, one neutron detector 31 </ b> A in the movement range Y is provided inside and outside the movement range Y of the sector 42. One neutron detector 31B) is installed outside. The moving range Y of the sector 42 is the same as the moving range X of the neutron reflector 9 in the above embodiment.

  As shown in FIG. 6, the neutron detectors 31 </ b> A and 31 </ b> B are accommodated in a guide tube 45 of a concrete frame 44 that is installed with a space 43 provided outside the reactor vessel 1. The guide tube 45 is embedded in the concrete housing 44 so as to extend in the axial direction of the core 2. The detection signals of the neutron count rates detected by the neutron detectors 31A and 31B installed for each sector 42 are summed in the same manner as in the above embodiment, and the neutron count rate of each sector 42 is calculated. A combined processing signal is obtained.

  Therefore, according to the present embodiment, the following effects can be obtained.

  Also when each sector 42 which divided | segmented the neutron reflector 41 moves independently, neutron detector 31A, 31B is installed inside and outside the moving direction Y of the said sector 42 for every sector 42, These The detection signals of the neutron count rates detected by the neutron detectors 31A and 31B are added together to obtain a combined processing signal. Therefore, even if the detection signals of the neutron detectors 31A and 31B fluctuate with the movement of the sector 42, the above summation processing signal reduces the influence of the fluctuation and reduces the detection error related to the neutron count rate. it can. Therefore, the neutron counting rate can be detected with high accuracy as the whole core 2, and the core 2 is operated at the rated output as in the first embodiment, so that the highly economical reflector control type fast reactor 40 can be obtained. realizable.

[C] Third embodiment (FIG. 7)
FIG. 7 (A) shows a part of the reflector control type fast reactor implemented in the third embodiment in the method for installing the neutron detector of the reflector control type fast reactor according to the present invention cut in the diameter direction. It is sectional drawing, (B) is sectional drawing which follows the VII-VII line of FIG. 7 (A). In the third embodiment, the same parts as those in the first and second embodiments and the background art are denoted by the same reference numerals, and the description will be simplified or omitted.

  In the reflector control type fast reactor 50 of this embodiment, in addition to the neutron detectors 31A and 31B of the first or second embodiment, the neutron flux distribution capable of measuring the axial neutron flux distribution of the core 2 is measured. A measuring device 51 is installed. The neutron flux distribution measuring instrument 51 is installed in the vicinity of the neutron detectors 31A and 31B of the first or second embodiment, and is provided so as to be movable in the axial direction of the core 2. For example, the neutron flux distribution measuring device 51 is accommodated in the guide tube 52 and provided so as to be movable along the axial direction of the guide tube 52. The guide tube 52 is accommodated in the guide tube 45 along the axial direction of the guide tube 45.

  The neutron flux distribution measuring device 51 is moved between the neutron detectors 31A and 31B along the axial direction of the core 2 to measure the distribution of the neutron flux along the axial direction of the core 2 at that time. it can. By analyzing the time series change of the neutron flux distribution, the detection signal of the neutron count rate detected by the neutron detectors 31A and 31B is also changed by the movement of the sector 42 of the neutron reflector 9 or the neutron reflector 41. It becomes possible to grasp the amount of fluctuation. Then, the positions of the neutron detectors 31A and 31B are adjusted so as to correct the fluctuation amount.

  For example, in the neutron detector 31B, as shown by the broken line B in FIG. 2, the detected neutron count rate is increased by the movement of the neutron reflector 9, but the neutron detector 31A is corrected so as to correct this increase. Adjust the position upward. The detection signals relating to the neutron count rates from the neutron detectors 31A and 31B thus adjusted in position are added together to obtain a combined processing signal.

  Therefore, according to this embodiment, in addition to the same effects as those of the first or second embodiment, the following effects can be obtained.

  The neutron flux distribution measuring device 51 installed in the vicinity of the neutron detectors 31A and 31B measures the neutron flux distribution in the axial direction of the core 2 and uses this neutron flux distribution to detect the detection signals of the neutron detectors 31A and 31B. The positions of the neutron detectors 31A and 31B are adjusted so as to correct the fluctuation amount when the fluctuation occurs due to the movement of the sector 42 of the neutron reflector 9 or the neutron reflector 41. As a result, fluctuations in detection signals from the neutron detectors 31A and 31B can be reduced, so that detection errors relating to the neutron count rates detected by these neutron detectors 31A and 31B can be further reduced. Therefore, it is possible to realize the reflector control type fast reactor 50 with higher.

[D] Fourth embodiment (FIG. 8)
FIG. 8: is the outline which shows (A) by cut | disconnecting the reflector control type fast reactor which implemented 4th Embodiment in the neutron detector installation method of the reflector control type fast reactor which concerns on this invention to an axial direction. FIG. 9B is a half cross-sectional view, and FIG. 9B is a diagram illustrating a moving position of the neutron reflector of FIG. In the fourth embodiment, the same parts as those in the first embodiment and the background art are denoted by the same reference numerals, and the description will be simplified or omitted.

  In the reflector control type fast reactor 60 in the present embodiment, one or more neutron detectors (one neutron detector 61 in the present embodiment) installed in the reactor vessel 1 are used as the neutron reflector 9. Following the movement, the core 2 is moved in the axial direction, whereby the neutron detector 61 is always positioned outside the moving range X of the neutron reflector 9, and a detection signal relating to the neutron count rate is obtained from the neutron detector 61. .

  Therefore, according to the present embodiment, the following effects can be obtained.

  Since the neutron detector 61 follows the movement of the neutron reflector 9 and moves in the axial direction of the core 2 and is always positioned outside the movement range X of the neutron reflector 9, the neutron count detected by the neutron detector 61 is detected. The detection signal of the rate is one in which the influence of fluctuation due to the movement of the neutron reflector 9 is mitigated, and the detection error related to the neutron count rate can be reduced. As a result, the thermal output error measured by the thermal output measuring device can be estimated to be small, and the core 2 can be controlled with the rated output, so that a highly economical reflector control type fast reactor 60 can be realized.

[E] Fifth embodiment (FIG. 9)
FIG. 9 is a block diagram showing a signal processing apparatus and the like for carrying out an embodiment of the reflector control type fast reactor operating method according to the present invention. In the fifth embodiment, the same parts as those in the first embodiment and the background art are denoted by the same reference numerals, and the description will be simplified or omitted.

  In the reflector control system fast reactor 70 of the present embodiment, a detection signal from any one of the first to fourth neutron detectors 31A, 31B, 61 is a signal for monitoring the reactor state other than this detection signal, For example, in combination with a thermal output signal and a position signal such as a neutron reflector, signal processing is performed so as to complement each signal error associated with the movement of the neutron reflector 9, and the core 2 is output-controlled to perform a reflector control type fast reactor 70 is driving.

  That is, in the reflector control type fast reactor 70, the signal processing device 71 includes an A / D converter 72 that performs A / D conversion on signals from the neutron detectors 31A, 31B, and 61, and a reflector position measuring device 73. From the A / D converter 74 for A / D converting the position signal of the neutron reflector, the heat output signal from the heat output measuring device 75, the signal from the A / D converter 72, and the A / D converter 74 The data storage device 76 for storing the above signals and the linear correction arithmetic device 77 for processing the signals stored in the data storage device 76 are configured.

  The reflector position measuring device 73 is installed on the drive device 22 (FIG. 10) side, for example, and measures the position of the sector 42 of the neutron reflector 9 or the neutron reflector 41 (position of the neutron reflector or the like). The thermal output measuring device 75 measures the thermal output from the temperature difference between the outlet and the inlet of the core 2 in the coolant.

  The linear correction calculation device 77 first adds up the detection signals of the neutron count rates detected by the neutron detectors 31A and 31B to obtain a combined processing signal. The detection signal of the neutron count rate detected by the neutron detector 61 is not added by the linear correction calculation device 77 but is used as it is for subsequent processing.

  Detection signals relating to the neutron counting rate from the neutron detectors 31A, 31B, 61, a thermal output signal measured by the thermal output measuring device 75, and a neutron reflector position signal measured by the reflector position measuring device 73 Fluctuates as the sector 42 of the neutron reflector 9 or neutron reflector 41 moves. Therefore, the linear correction calculation device 77 combines the sum processing signal or detection signal related to these neutron count rates, the heat output signal, and the position signal such as the neutron reflector, and complements the error of each signal. As a result, the combined processing signal or detection signal, thermal output signal, and neutron reflector position signal related to the neutron count rate are more influenced by the fluctuations that occur as the sector 42 of the neutron reflector 9 or neutron reflector 41 moves. It becomes small and the error of each signal can be reduced.

  The linear correction calculation device 77 further calculates a nuclear output by using the combined processing signal or detection signal related to the neutron count rate, the thermal output signal, and the neutron reflector isoposition signal, and outputs the nuclear output to the nuclear output display device 78. Display. In the reflector control type fast reactor 70, the sector 42 of the neutron reflector 9 or the neutron reflector 41 is moved based on the nuclear power calculated by the linear correction arithmetic unit 77, and the reactivity of the core 2 is controlled. .

  Therefore, according to the present embodiment, the following effects can be obtained.

  The detection signals from the neutron detectors 31A, 31B, 61 are combined with a signal having a function of monitoring the reactor state other than the detection signals (for example, a thermal output signal, a position signal such as a neutron reflector), and the neutron reflector 9 or Since the signal processing is performed to complement the error of each signal accompanying the movement of the sector 42 of the neutron reflector 41 and the output of the core 2 is controlled, the error of each signal is reduced, so that a highly reliable core Therefore, the reflector control type fast reactor 70 can be realized.

(A) is a schematic half sectional view showing the reflector control type fast reactor implemented in the first embodiment in the method for installing a neutron detector of the reflector control type fast reactor according to the present invention cut in the axial direction; FIG. 2B is a diagram illustrating a moving position of the neutron reflector of FIG. The graph which shows the neutron count rate etc. which were detected by the neutron detector of FIG. 1 (A). (A) is a schematic half sectional view showing the reflector control type fast reactor in which the installation position of the neutron detector of FIG. 1 (A) is changed in the axial direction, and (B) is the neutron of FIG. 3 (A). The figure which shows the movement position of a reflector. (A) is a schematic half sectional view showing the reflector control type fast reactor in which the installation position of the neutron detector of FIG. 1 (A) is changed in the axial direction, and (B) is the neutron of FIG. 4 (A). The figure which shows the movement position of a reflector. (A) is schematic sectional drawing which cut | disconnects and shows the reflector control type fast reactor which implemented 2nd Embodiment in the neutron detector installation method of the reflector control type fast reactor which concerns on this invention in an axial direction, (B ) Is a diagram showing the movement position of the neutron reflector of FIG. Sectional drawing which cut | disconnects and shows the reflector control type fast reactor of FIG. (A) is a partial cross-sectional view showing a reflector control type fast reactor in which the third embodiment of the method for installing a neutron detector of a reflector control type fast reactor according to the present invention is cut in the diameter direction; ) Is a cross-sectional view taken along line VII-VII in FIG. (A) is a schematic half sectional view showing the reflector control type fast reactor in which the fourth embodiment in the neutron detector installation method of the reflector control type fast reactor according to the present invention is cut in the axial direction; FIG. 9B is a diagram illustrating a moving position of the neutron reflector of FIG. The block diagram which shows the signal processing apparatus etc. which implement one Embodiment in the operating method of the reflector control system fast reactor which concerns on this invention. The half sectional view which cuts and shows the conventional reflector control system fast reactor to an axial direction. Sectional drawing which cut | disconnects and shows the reflector control type fast reactor of FIG. 10 in the diameter direction. FIG. 12 is a longitudinal sectional view showing the fuel assembly of FIG. 11. (A) is a schematic sectional view showing the reflector control type fast reactor of FIG. 10 cut in the diameter direction, and (B) is a graph showing the movement position of the neutron detector of FIG. 13 (A). The graph which shows the neutron count rate detected by the neutron detector of FIG.10 and FIG.13. (A) is a schematic half sectional view showing the reflector control type fast reactor in which the installation positions of the neutron detectors shown in FIGS. 10 and 13 are changed in the axial direction, and (B) is the neutron of FIG. 15 (A). The figure which shows the movement position of a detector. The graph which shows the neutron count rate detected by the neutron detector of FIG. 15 (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reactor vessel 2 Core 9 Neutron reflector 30 Reflector control system fast reactor 31A, 31B Neutron detector 40 Reflector control system fast reactor 41 Neutron reflector 42 Sector 50 Reflector control system fast reactor 51 Neutron flux distribution measuring device 60 Reflector control type fast reactor 61 Neutron detector 70 Reflector control type fast reactor 73 Reflector position measuring device 75 Thermal output measuring device X, Y Movement range

Claims (7)

Reflection that controls the reactivity of the core by adjusting the leakage of neutrons from the core by moving a neutron reflector installed outside the core contained in the reactor vessel in the axial direction of the core. In the neutron detector installation method of the reflector control system fast reactor, which is a body control system fast reactor, and the neutron detector is installed outside the reactor vessel,
A plurality of the neutron detectors are installed in the axial direction of the core, at least one of which is installed within the moving range of the neutron reflector, and at least one of the neutron detectors is installed in the neutron reflection Install outside the range of movement of the body,
A method for installing a neutron detector in a reflector-controlled fast reactor, characterized in that the signals of the neutron detectors installed inside and outside the moving range are summed up. The neutron detector installed in the moving range of the neutron reflector is arranged on the core side, and the neutron detector installed outside the moving range is arranged in the core lower part, core upper part or core bottom part, The neutron detector installation method of the reflector control type fast reactor according to claim 1. When the neutron reflector is divided in the circumferential direction and is composed of a plurality of sectors, and each sector moves independently in the axial direction of the core, each of these sectors has a moving range inside and outside the sector. The method for installing a neutron detector for a reflector controlled fast reactor according to claim 1 or 2, wherein at least one neutron detector is installed. A neutron flux distribution measuring device capable of moving in the axial direction of the core and measuring the neutron flux distribution in the axial direction of the core in the vicinity of the neutron detectors respectively installed outside the moving range of the neutron reflector. 4. The method for installing a neutron detector for a reflector controlled fast reactor according to claim 1, wherein the neutron detector is installed. Reflection that controls the reactivity of the core by adjusting the leakage of neutrons from the core by moving a neutron reflector installed outside the core contained in the reactor vessel in the axial direction of the core. In the neutron detector installation method of the reflector control system fast reactor, which is a body control system fast reactor, and the neutron detector is installed outside the reactor vessel,
A method for installing a neutron detector in a reflector controlled fast reactor, wherein the neutron detector is moved in the axial direction of the core following the movement of the neutron reflector. The detection signal from the neutron detector according to any one of claims 1 to 5 is combined with a signal having a function of monitoring the reactor state other than the detection signal, and an error of each signal accompanying the movement of the neutron reflector The reflector control type fast reactor operating method is characterized by controlling the reactor power by performing signal processing so as to complement the above. Reflection that controls the reactivity of the core by adjusting the leakage of neutrons from the core by moving a neutron reflector installed outside the core contained in the reactor vessel in the axial direction of the core. In the body-controlled fast reactor,
Outside the reactor vessel, a plurality of neutron detectors are installed in the axial direction of the core, at least one of which is installed within the moving range of the neutron reflector, and at least one The neutron detector is installed outside the range of movement of the neutron reflector,
A reflector controlled fast reactor characterized in that the signals of the neutron detectors respectively installed outside the moving range are combined.

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