JPH08271674A - Diagnostic method and device for remaining life of reactor - Google Patents

Abstract

PURPOSE: To provide a method and device for diagnosing remaining life of a reactor by accurately grasping the irradiation dose of neutron at each part of a reactor and predicting the aging degradation of in-core structure. CONSTITUTION: A small neutron flux detector 44 is inserted from outside of a reactor pressure vessel 1 and used during reactor operation by positioning more than one measuring position in the vicinity of structure material arranged around fuel assemblies. The neutron flux detected at the measuring position by the small neutron flux detector 44 is measured with a neutron flux measuring device 56 and the measured value is recorded on a neutron flux recorder 58. By evaluating neutron irradiation dose to the structure material of in-core structure at the measuring position based on the measured record of the neutron flux accumulated in the neutron flux recorder 58 and the reactor operation record, the aging degradation of the in-core structure using degradation characteristics data of various structure material and remaining life is diagnosed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for diagnosing the remaining life of a nuclear reactor by predicting the deterioration of the reactor internal structure from the amount of neutron irradiation received by the structural material, and an apparatus therefor.

[0002]

2. Description of the Related Art When conducting a neutron irradiation test on structural materials in an experimental furnace or the like, Co called flux wire,
In metals such as Fe, Ni, Cu, Ta (n,
γ), (n, p), (n, α), (n, n ′) Neutrons to the structural material by measuring the neutron flux by measuring the emission rate of α, β, γ rays due to the nuclear reaction Non-fissile dosimeters for measuring irradiation dose have been conventionally known. Also,
In the "Monitoring Test Method for Reactor Structural Materials" described in JEAC-4201-1986, Fe, Ni, Co are recommended as neutron dosimeters suitable for monitoring test pieces of reactor pressure vessels for power generation. There is.

For example, in a pressurized water reactor as shown in FIG. 8, as can be seen from the vertical sectional view of FIG. 8A and the horizontal sectional view of FIG. 8B, the reactor vessel 10 and the core shroud 11 around the core are shown. The irradiation capsule 14 of the monitoring test piece of the reactor vessel 10 is loaded on a part of the outer wall of the thermal shield 12 located outside the. Therefore, this irradiation capsule 14
It is considered to load the neutron dosimeter described above as a monitor.

In a boiling water reactor as shown in FIG. 9, the reactor pressure between the reactor pressure vessel 1 and the core shroud 2 can be seen from the longitudinal sectional view showing the main part of FIG. A basket 4 in which a monitoring test piece of the reactor pressure vessel 1 is incorporated is loaded on a part of the inner wall 1a of the vessel 1, and moreover, in a region where the neutron flux is high, a dose higher than the dose received by the reactor pressure vessel 1 is exceeded. As a position for accelerated irradiation, a basket 8 of accelerated irradiation test pieces is loaded on a part of the outermost peripheral portion 3a of the upper grid plate 3 as shown in FIG. In this case as well, it is considered to load the above-mentioned neutron dosimeter in the baskets 4 and 8 together with the test piece.

In this case, for example, the monitoring test piece basket 4
It is necessary to take out the neutron todimeter loaded into the reactor when the reactor is shut down for maintenance and other purposes, and measure neutrons in a laboratory equipped with a hot cell outside the reactor.
That is, in the case of the boiling water reactor shown in FIG. 9, the neutron dosimeter loaded in the monitoring test piece basket 4 with the basket holder 5 fixed to the lower basket 6 and the upper support 7 is taken out, Neutrons must be measured in a laboratory with an external hot cell. Further, since the neutron dosimeter is fixed to the monitoring test piece basket 4, the neutron measurement position is limited, and not all neutron irradiation doses of the structures inside the nuclear reactor can be monitored. Further, the effective neutron energy ranges suitable for Fe, Ni, and Co recommended as neutron dosimeters are Fe: 2 to 8 MeV or 0.2 keV or less Ni: 2 to 8 MeV Co: 0. It was 1 keV or less, and there was a difficulty in measuring the energy region between these (between 0.2 keV and 2 MeV). In general, the damage of structural materials by neutrons is contributed by the irradiation dose of neutrons in the energy region of 0.1 to 1 MeV or more. Therefore, it is necessary to accurately grasp this region in order to evaluate the damage by irradiation of materials. is important.

FIG. 10 is a perspective view showing the internal structure of a boiling water reactor. The boiling water reactor is configured by installing a core shroud 2 supported by a shroud support 15 in a reactor pressure vessel 1, and arranging fuel rods 17 in a core in the core shroud 2. A core support plate 16 is provided below the core shroud 2, and an upper lattice plate 3 is provided above the core shroud 2. A fuel rod is arranged between the upper lattice plate 3 and the core support plate 16 by a control rod 17 so that the fuel rod can move up and down. A plurality of fuel rods are arranged side by side to form a fuel rod assembly 25. Control rod 1
7 is vertically movably guided by a control rod guide tube 18, and is vertically moved by a control rod drive mechanism 19 housed in a control rod drive mechanism housing 20 provided in the lower portion of the reactor pressure vessel 1. A reactor core instrumentation monitor housing 21 is provided below the reactor pressure vessel 1, and holds the reactor core instrumentation monitor. Further, a neutron instrumentation pipe 22 extends from the lower part of the reactor pressure vessel 1 toward the inside of the reactor core, and a neutron monitor 28 for monitoring thermal neutrons is arranged in the instrumentation pipe 22 for managing the core where fission occurs. ing. A steam separator 26 and a steam dryer 27 are installed above the upper lattice plate 3, and a jet pump 23 and a jet for forcedly circulating reactor water between the core shroud 2 and the reactor pressure vessel 1 are installed. A pump riser 24 is provided.

In the boiling water reactor having the above-mentioned general structure, the nuclear reactor instrumentation system system including the neutron monitor 28 for monitoring thermal neutrons is provided for managing the core where fission occurs as described above. However, this system is to monitor the power level of the reactor from start-up to full power operation and prevent damage to the fuel cladding.
Startup area monitor (SRNM), average output area monitor (P
RNM), and mobile in-core instrumentation (TIP).

FIG. 11 is a view showing an example of the arrangement of neutron monitors in the boiling water reactor shown in FIG. 10, in which a plurality of start-up area monitors 31a and 31b are arranged in the core. The start-up area monitors 31a and 31b supply information obtained by monitoring the neutron flux belonging to the neutron source area and the intermediate area. The fission ionization chamber, the full-amplifier, the power supply device, the display and the record (not shown). It is composed of a total.

12 and 13 show the structure of the neutron monitor in the boiling water reactor of FIG. In FIG. 12, the fission ionization chamber includes a core upper end 59 to a core lower end 60.
Neutron monitor holder 31 so that the area of
It is enclosed in the inner cal tube 29.

The average power range monitor (PRNM) is a local power range monitor (L) using a detector provided in the core.
PRM), an average power range monitor (APRM), and a core flow rate measuring device for obtaining the core flow rate from the differential pressure between cores. As shown in FIG. 11, a plurality of local power range monitors (LPRMs) 28 are arranged in the core.
As shown in Fig. 3, a stationary neutron flux detector composed of four small fission ionization chambers 30 arranged between the core upper end 59 and the core lower end 60 is arranged at equal intervals in the axial direction of the core. And a signal processing device. Further, the average output monitor (APRM) is configured by a device that averages the output signals from the respective amplifiers of the local output area monitor (LPRM) grouped in advance. The mobile in-core instrumentation device (TIP) is for calibrating the local power range monitor (LPRM) and for measuring the neutron flux distribution in the axial direction of the core, and includes a detector (not shown) and a calibration conduit index device TIP. It consists of a guide tube, a drive, a display and a recorder.

[0011]

The various devices constituting these nuclear reactor instrumentation system systems are devices for the purpose of managing the fuel state of nuclear fuel assemblies, that is, core management. Therefore, although the measurement range is finely divided so that it can be measured according to each power level of the core, it is not used to evaluate the structural material of the reactor, especially the neutron flux detector. Is 0.1 in the core
The main purpose is to measure the thermal neutron flux at a level of about eV. Therefore, in the neutron flux detector, U234 or U235 is used as a detection substance in the fission ionization chamber. In addition to the problem that the structural material and the measurement position are distant from each other in distance, the problem caused by the damage of the structural material by neutrons is that the irradiation dose of neutrons in the energy range of 0.1 MeV or 1 MeV or more is conventionally. This means that the measured values of the detectors provided by the can not be used as they are, so it is not possible to accurately determine the amount of fast neutron irradiation received by the structural material.

The neutron flux density distribution in the core is obtained by diffusion theory calculation, transport theory calculation or Monte Carlo calculation, and the neutron flux and neutron spectrum at the position away from the core are obtained by the transport calculation method. Also in this case, the analysis accuracy in the region where the distribution is changed rapidly is not always sufficient.

Further, the monitoring test piece of the reactor pressure vessel is monitored by a surveillance basket, the inner wall of the pressure vessel, the outer peripheral portion of the upper lattice plate, the outer wall of the thermal shield, and the like. Although the level is limited, some useful information can be obtained. However, for the lower end of the central part of the upper lattice plate, the inner wall of the core shroud belt line, and the upper end of the central part of the core support plate, which are expected to receive neutron irradiation most frequently during the operation of the reactor, It was difficult to make a measurement.

In addition, since the nuclear reactor instrumentation system described above targets only the core region for the purpose of core management, it does not have a function of directly monitoring the amount of fast neutron irradiation received by surrounding structures. Since only thermal neutron flux with low energy level is measured among neutrons, fast neutron flux, which affects the structural materials, could hardly be measured. In addition, the distribution of neutron flux in regions outside the core was rapidly reduced due to attenuation by reactor water, but it was not possible to directly understand the distribution state of such neutron flux.

The present invention has been made in view of the actual situation of the prior art as described above, and its purpose is to accurately grasp the neutron irradiation amount of each part in the reactor and to predict the aged deterioration of the internal structure of the reactor. A method and apparatus for diagnosing the remaining life of a nuclear reactor.

[0016]

In order to achieve the above object, a first means is to provide a reactor pressure vessel, a fuel assembly arranged in the reactor pressure vessel, and the fuel assembly at a predetermined position. In the method for diagnosing the remaining life of a nuclear reactor with the internal structure to be held in, the measuring means for measuring the neutron flux from outside the reactor pressure vessel is inserted during the reactor operation. Characterized in that the deterioration of the material due to neutrons of the reactor internal structure in the vicinity of the measurement site is predicted based on the measurement value measured by the measuring means, and the remaining life of the reactor is diagnosed according to the predicted deterioration state. I am trying.

In this case, it is desirable that the neutron flux to be measured is a high-speed and / or medium-speed neutron flux, and the site where the measuring means is inserted is selected, for example, near the structure around the fuel assembly. It In addition, the prediction of the deterioration of the material, the neutron irradiation dose to the structure from the measurement results,
The aging deterioration characteristic of the structure is determined by using the aging deterioration data of the structural material prepared in advance, and the residual life is diagnosed by the aging deterioration characteristic obtained and the measured portion of the in-core structure. The stress evaluation data is used.

A second means is a method for diagnosing remaining life of a reactor based on the same premise, in which a structure in a reactor pressure vessel is irradiated with medium-speed and / or high-speed neutrons accumulated at the time of shutdown of the reactor. A measuring means for measuring the amount is attached, the operation of the nuclear reactor is restarted, and when the nuclear reactor is stopped again, the measuring means is taken out of the reactor, and the furnace near the measurement site is based on the measured value measured by the taken out measuring means. The feature is that the deterioration of the material due to neutrons in the internal structure is predicted and the remaining life of the reactor is diagnosed according to the predicted deterioration state.

In this case, the measuring means comprises a first measuring means for measuring a low speed neutron flux in the core and a second measuring means for measuring a high speed and / or a low speed neutron flux outside the core. Good to do. The second measuring means may be provided in at least one of the activation area monitor holder and the average output area monitor holder.

A third means is a reactor equipped with a reactor pressure vessel, a fuel assembly arranged in the reactor pressure vessel, and an internal structure for holding the fuel assembly in a predetermined position. In the reactor remaining life diagnosis device for diagnosing the remaining life of
Measuring means for measuring the neutron flux emitted from the fuel assembly, and insert this measuring means from the outside of the reactor pressure vessel to the desired position inside the reactor, and set it to the desired position, and after measurement the position Drive means of the measuring means to be extracted from the recording means, recording means for recording the neutron flux measured by the measuring means, and measurement based on the measurement record of the neutron flux recorded in the recording means and the operation record of the reactor A neutron dose analysis means for calculating the neutron dose to the core structure at the position, and a diagnostic means for diagnosing the remaining life of the internal structure from the dose of neutrons analyzed by the neutron dose analysis means. It is characterized by

In this case, the insertion of the measuring means by the driving means into the reactor is carried out during the operation of the reactor. Also,
In addition to the third means, a neutron dosimeter for measuring the accumulated amount of slow neutrons may be provided at a preset position. Further, the neutron dose analysis means, neutron flux measured in real time by the measuring means,
The neutron irradiation dose may be calculated based on the accumulated amount of neutrons by the neutron dosimeter. in addition,
The driving means may move the measuring means to a desired measurement position during the operation of the nuclear reactor, and the measuring means may measure the neutron flux at the moved position.

As the measuring means, ⁶³ Cu (n,
α) ⁶⁰ Co nuclear reaction, ⁵⁵ Mn (n, 2n) ⁵⁴ Mn nuclear reaction,
⁵⁴ Fe (n, p) ⁵⁴ Mn nuclear reaction, ⁴⁶ Ti (n, p) ⁴⁶ S
c nuclear reaction, ⁵⁸ Ni (n, p) ⁵⁸ Co nuclear reaction, and ³² S
A threshold detector that utilizes any of the (n, p) ⁵² P nuclear reactions can be used. Further, as the measuring means, a U235Cd filter is attached, Nb93 / Ag1
09Cd filter, Co59Cd filter, Ni6
0, Fe54, Ti64, Np237, Ni58, Fe
With 58Cd filter, Sc45Cd filter, Ta1
It is possible to use a neutron flux detector that uses either a substance with an 81 Cd filter or a substance with a Pu 239 Cd filter.

Further, the driving means includes a wire having a measuring means at its tip, a cal tube extending vertically inside the reactor, and a movable in-core instrumentation device guide extending below the reactor pressure vessel. The wire drive device for advancing and retracting the inside of the tube, and the drive control device for positioning the measuring means at an arbitrary measurement position of the core along the cal tube via the wire drive device, the drive control device is The measurement means can be housed in a shielded container outside the reactor so that the measurement result of the neutron flux can be recorded by the recording means.

A fourth means is a neutron dosimeter for measuring the accumulated amount of neutrons emitted from a fuel assembly in a residual life diagnostic device for a nuclear reactor of the same premise, and this neutron dosimeter during operation shutdown of the reactor. Setting means to be set to the measurement position preset in advance, after restarting the operation of the nuclear reactor, when the neutron dosimeter is taken out of the reactor when restarted, recording means for recording the accumulated amount of measured neutrons, Neutron dose analysis means for calculating the neutron dose to the core structure at the measurement position based on the measurement record of the neutron flux recorded in the recording means and the operation record of the reactor, and by the neutron dose analysis means It is characterized by including a diagnostic means for predicting the state of deterioration of the internal structure of the reactor from the analyzed dose of neutrons and diagnosing the remaining life from the state of deterioration. There.

In this case, as the neutron dosimeter,
Li6, B10, Ni58, In115, Ta181,
Au197, Ag109, Th232, U235, Co
59, Fe58, Mn55, Cu63, Pu239, N
It is recommended to use any one of a23, Sc45 and Fe54.

[0026]

According to the first means, the measuring means is inserted into the reactor pressure vessel during the operation of the reactor, and the neutrons emitted from the fuel assembly of the nuclear reactor are measured in real time by the measuring means. Then, the measuring means is taken out of the reactor during the operation of the nuclear reactor, and the state of deterioration of the internal structure in the vicinity of the measurement site is predicted based on the measurement value of the measuring means. This prediction is performed, for example, by obtaining aging characteristics using aging data of the structural material prepared in advance. Then, the remaining life is diagnosed based on the aged deterioration characteristics and the stress evaluation data of the measured portion of the reactor internal structure.

In the second means, a measuring means for accumulating and measuring the irradiation dose of neutrons is attached to the structure inside the reactor pressure vessel at the time of shutdown of the reactor such as periodical inspection, and the operation of the reactor is restarted. When the reactor is shut down at the next periodic inspection, etc., the measuring means is taken out of the reactor, and the state of the internal structure in the vicinity of the measurement site is predicted from the accumulated amount of neutrons. Diagnose remaining life.

In this case, the measuring means does not measure the low-speed neutrons that have been conventionally installed in the reactor for measurement, but measure the high-speed or medium-speed neutrons that have not been conventionally measured. Therefore, the holder of the conventional measuring device, for example, the start-up area monitor holder and the average output area monitor holder can be installed at a predetermined position for measurement.

In the third means, the driving means inserts the measuring means into a desired position in the operating nuclear reactor, measures for a predetermined time, and then extracts the neutron flux outside the reactor to measure the neutron flux. Then, the measurement result of the neutron flux at the measurement position is recorded in the recording means. The neutron dose analysis means calculates the neutron dose to the core structure at the measurement position based on the measurement result and the operation record of the reactor, and the diagnostic means is near the measurement site from the calculated dose of neutrons. Of the core structure is predicted, and the remaining life of the reactor is diagnosed based on the deterioration state.

In the fourth means, the neutron dosimeter is set at a preset measurement position when the reactor is shut down, and after the restart of operation, the neutron dosimeter is measured until it is shut down again, and the measured value is measured. Based on this, the remaining life of the nuclear reactor is diagnosed in the same manner as the third means.

[0031]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory diagram showing a schematic structure of a residual life monitoring apparatus for a nuclear reactor according to an embodiment of the present invention. In the following description, the same parts as those in the above-mentioned conventional example are designated by the same reference numerals, and the duplicated description will be omitted. The structure of the nuclear reactor is the same as that of the conventional pressurized water reactor or boiling water reactor.

In FIG. 1, the neutron flux is measured by neutron monitors such as a plurality of local power range monitors 45, 46, 47, 48 set at different positions in the core area inside the reactor pressure vessel 1. In order to measure the neutron flux in the region from the lower end 60 to the reactor bottom of the reactor pressure vessel 1, a small neutron flux detector 44 suitable for detecting fast neutrons is set at the lower part of the core lower end 60, and the reactor pressure is set. The neutron flux distribution is measured by measuring the position of the detector 44 in the space up to the bottom of the container 1 and the neutron flux at that position. Here, the detector 44 has 0.1M
As a substance suitable for measuring neutrons having an energy of eV or 1 MeV or more, with U235Cd filter, N
b93, with Ag109Cd filter, with Co59Cd filter, Ni60, Fe54, Ti46, Np237,
With Ni58, Fe58Cd filter, Sc45Cd filter, Ta181Cd filter, or Pu23
If the one with a 9Cd filter is used, the half-life is 10 days or more, which is suitable as a measuring instrument.

As the detector 44, ⁶³ Cu
(N, α) ⁶⁰ Co nuclear reaction, ⁵⁵ Mn (n, 2n) ⁵⁴ Mn nuclear reaction, ⁵⁴ Fe (n, p) ⁵⁴ Mn nuclear reaction, ⁴⁶ Ti (n,
A threshold detector utilizing any one of p) ⁴⁶ Sc nuclear reaction, ⁵⁸ Ni (n, p) ⁵⁸ Co nuclear reaction, and ³² S (n, p) ⁵² P nuclear reaction can also be used. .

The detector 44 is moved by reciprocating the inside of the cal tube 29 penetrating the inside of the neutron monitor holder 28. The detector 44 is connected to the wire 54a from the wire driving device 54, and passes through the reactor containment penetrating portion 50 and via the isolation valve 51 and the remote cutoff valve 52 arranged outside the reactor pressure vessel 1, The shield container 53 can be moved. The measurement data of the neutron flux measured at a desired position by the detector 44 is input to the neutron flux measuring device 56 in real time via a cable (not shown). The valve operation of the isolation valve 51 and the remote cutoff valve 52 is for emergency and is remotely operated by the valve controller 57. The drive control device 55a is a device for switching and inserting the detector 44 into another neutron monitor arranged in the circumferential direction of the core, and is controlled by the drive control device 55b.
Data such as positioning and position information is stored in the file. The position information data and the measurement data (neutron information data) of the neutron flux measured by the detector 44 are filed by the neutron flux measuring device 56 via a cable. Then, this neutron flux information data is accumulated in the neutron flux recording device 58, and the neutron flux distribution inside the reactor pressure vessel 1 is analyzed and displayed.

FIG. 2 shows a neutron flux measuring device in the bottom region of the reactor pressure vessel 1 in the reactor residual life monitoring device. This measuring device includes a neutron flux recording device 58,
Neutron irradiation amount analysis device 63, structural material aging deterioration prediction evaluation analysis device 65, equipment structural material stress analysis evaluation device 66
And the remaining life evaluation analysis device 67 and the analysis result display device 68
And a neutron dosimeter information file 61,
The core operation data file 62 and the structural material aged deterioration data file 64 are referred to and analyzed. That is, when the neutron flux is measured, first, the neutron flux of the portion to be evaluated in the structure is determined based on the neutron flux data stored in the neutron flux recording device 58 or the information file 61 by the neutron dosimeter. Along with the core operation data file 6
After obtaining the core operation time based on 2, the neutron irradiation amount analyzer 63 calculates the irradiation amount of neutrons to the evaluation target part up to that point using these pieces of information. Then, by using the analysis data thus obtained and the physical property data in the structural material aging deterioration data file 64, stainless steel, nickel-based alloy,
Aging deterioration predictive evaluation is performed for nuclear reactor structural materials such as low alloy steel, and mechanical properties such as fracture toughness value, tensile strength and elongation, and aging characteristics such as corrosion resistance are calculated for each material. Further, based on this result and the stress evaluation data of the part of the evaluation target device which is separately obtained by the device structural material stress analysis evaluation device 66, the remaining life analysis device 67 determines the life or the remaining life of the evaluation target portion at the time of the evaluation. . These results are displayed online by the analysis result display device 68 in the central control room or the evaluation organization.

FIG. 3 is a diagram showing an example of the arrangement of the neutron monitor portion of FIG. In the figure, a local power range monitor (LPRM) instrument housing 28 is provided in the lower portion of the reactor pressure vessel 1, and a local power range monitor (LPRM) guide tube 61 extends from the housing 28 to the core support plate 16 upward. , The local output area monitor (L
A PRM) holder 22 is arranged and extends to the upper lattice plate 3. As a result, the local power range monitor (LPRM) can be moved up and down via the mobile in-core instrumentation (TIP) guide tube 49. In the figure, reference numeral 62 is a control rod guide tube.

In the present embodiment, in addition to being able to measure the neutron flux in the core region 13, a local power range monitor (LPRM) guide tube including the core support plate 16 in a region that could not be measured in the past was used. It is possible to measure the neutron flux in the vicinity of structures located outside the core, such as the control rod guide tube 62 and the control rod guide tube 62. Furthermore, as an application of this embodiment, the detector is replaced with a detector for medium-speed and fast neutrons by using an existing mobile in-core instrumentation device (TIP), and the neutron flux near the structure is temporarily changed. Can also be measured.

FIG. 4 shows another embodiment of the present invention. In this embodiment, a device for measuring neutron dose of medium speed or high speed is attached to a structure in a reactor pressure vessel while the reactor is stopped, the reactor is put into operation, and thereafter, when the operation is stopped, A device configured to take out a device for measuring neutron irradiation from the reactor pressure vessel, measure the neutron irradiation, and evaluate the deterioration of the structural material at the site to be measured due to neutron irradiation based on the result Is.

The upper lattice plate 3 is one of the sites in the reactor pressure vessel 1 where the amount of neutron irradiation received is expected to increase. In this embodiment, a neutron dosimeter 42 is loaded on a part of the channel fastener guard 35 for fixing the channel box 34 of the fuel assembly in order to accurately measure the neutron irradiation dose at this portion. That is, the upper portion of the fuel rod 40 and the fuel rod 40
A neutron dosimeter 42 is mounted on a lower end portion of a channel fastener guard 35 provided along the outside of a fuel channel box 34 accommodating an upper tie plate post 39 to which an upper end portion of the neutron dosimeter 42 is mounted via an neutron dosimeter holder 41. Attach it at the same level as the bottom edge of 3. The channel fastener guard 35 is attached via a spring 36 and a washer 38 by a set screw 37 that is screwed onto an upper tie plate post 39 on the upper surface of the channel box 34. By doing so, the neutron dosimeter 42 can be easily taken out by loosening the set screw 37 and removing the channel fastener guard 35 at the time of fuel exchange performed at the time of regular inspection. Further, when a new neutron dosimeter is attached, it can be attached via the set screw 37. The neutron dosimeter 42 includes Li6, B10, Ni58, In115, Ta as a dosimeter for medium speed neutrons.
181, Au197, Ag109, Th232, U23
5, Co59, Fe58, Mn55, Cu63, Pu2
39, Na23, Sc45, Fe54, etc. are suitable. As a fast neutron dosimeter, Np23
7, Rh103, Nb93, In115, N14, U2
38, Th232, Be9, Ti47, Ni58, Fe
54, S32, Fe56, Cu63, Al27, Ti4
8, 47, Ni60, Mn55, etc. are suitable, and the neutron dosimeter 42 composed of one or a combination of a plurality of these substances is attached as described above.

FIG. 5 shows the positional relationship between the upper lattice plate 3 of the reactor pressure vessel and the neutron dosimeter 42 attached to the fuel channel fastener 32. In the figure, the neutron dosimeter 42 is located in the central portion of the grid of the upper lattice plate 3, and by selecting the fuel assembly 33 in the central portion of the core, the upper lattice which is expected to have the highest irradiation dose. The irradiation amount of the plate 3 can be easily measured. The data indicating the neutron irradiation dose measured in this way is the neutron dosimeter 4
2 is taken out of the reactor when the reactor is out of operation, then measured by an analyzer for a neutron dosimeter in a laboratory with a hot cell, analyzed, and then evaluated. This data is
It is stored in the neutron dosimeter information file 61 in FIG. 2 described above, and the subsequent evaluation analysis is as described above.

Although the neutron dosimeter 42 is attached to a part of the fuel channel fastener guard 35 in the embodiment shown in FIG. 4, the neutron dosimeter 42 can be attached to a part of the fuel channel fastener 34. An example of this is shown in FIG. That is, in this example, the neutron dosimeter 4
2 is attached to a fuel channel fastener 34 conventionally located near the upper lattice plate 3 of the reactor pressure vessel 1. With this configuration, it is not possible to measure the neutron irradiation dose at the lowermost end of the upper lattice plate 3, but it is possible to measure the neutron irradiation dose near the upper end. Note that, in FIG. 6, each unit not particularly described has the same configuration as that of the embodiment shown in FIG.

Furthermore, the neutron dosimeter 42 is shown in FIG.
As shown in (a), it is attached in the vicinity of the core support plate 16 on the inner surface of the neutron monitor holder 31 of the SRM or IRM in the conventional example (see FIGS. 12 and 13) as shown in (b). In this example, the neutron dosimeter 42 is located slightly above the central portion 43 of the core support plate 16 by the neutron dosimeter holder 41. These neutron monitors 30
The neutron dosimeter 42 loaded at that time is replaced because it is replaced every year for a certain period with the operation of the reactor.
Take it out and bring it into the hot cell, and measure the measured neutron dose. The remaining life evaluation of the structure thereafter is the same as that in the above-mentioned embodiment.

[0044]

As is apparent from the above description, according to the present invention, the neutron irradiation dose of the structure at a desired position of the reactor pressure vessel can be accurately controlled including the outside of the core region during the operation of the reactor. Since it can be grasped well, it is possible to predict the aged deterioration of the measurement site, and thereby to estimate the remaining life. Further, it becomes possible to take appropriate measures according to the estimated remaining life, and the reliability of the nuclear reactor can be improved.

That is, according to the invention of claim 1,
Since the measuring means for measuring the neutron flux from outside the reactor pressure vessel during operation of the reactor is inserted into the core region and the desired position outside the core region for measurement, the neutron irradiation amount at the time of measurement is grasped in real time. Therefore, the remaining life can be accurately diagnosed.

According to the second aspect of the present invention, the neutron flux to be measured is not a slow neutron flux which has been conventionally implemented, but a neutron flux which cannot be conventionally implemented has a high speed and / or a medium speed. Since it is a neutron flux, it is possible to grasp the irradiation amount of neutrons, which could not be grasped conventionally, so that it is possible to accurately diagnose the remaining life.

According to the third aspect of the present invention, since the portion into which the measuring means is inserted is near the structure around the fuel assembly, it is possible to measure the portion where the neutron exposure amount is the largest and the deterioration is greatest. The exposed state of the part can be grasped, and the remaining life can be diagnosed with high accuracy.

According to the invention described in claim 4, the deterioration of the material is predicted by obtaining the neutron irradiation dose for the structure from the measurement result and using the prepared deterioration data of the structural material over time. Since it is performed by obtaining the characteristics, it is possible to accurately predict the deterioration.

According to the fifth aspect of the present invention, the remaining life is diagnosed based on the obtained deterioration characteristics over time and the stress evaluation data of the measured portion of the in-core structure, so that accurate diagnosis can be performed. It will be possible.

According to the sixth aspect of the present invention, when the operation of the nuclear reactor is stopped, a measuring means for measuring the accumulated dose of medium-speed and / or high-speed neutrons is attached, and the operation of the nuclear reactor is restarted. Since the irradiation amount of neutrons is measured when the neutrons are stopped, accurate residual life can be diagnosed based on the accumulated amount of neutrons over time.

According to the invention of claim 7, the measuring means measures the low-speed neutron flux in the core, and the high-speed and / or medium-speed neutron flux outside the core. Since it comprises the second measuring means, it becomes possible to measure the accumulated amount of neutron flux having a plurality of characteristics at various points in the reactor, and thereby grasp the distribution of accumulated amount of neutrons in the reactor. Therefore, the remaining life can be accurately diagnosed from the accumulated amount distribution.

According to the invention as set forth in claim 8, since the second measuring means is provided in at least one of the starting area monitor holder and the average output area monitor holder, the means for mounting the reactor in the reactor is a low-speed neutron. It can be shared with measuring means.

According to the invention described in claim 9, since the driving means can insert the measuring means at a desired position in the reactor at a desired timing to measure the neutron flux,
The irradiation dose and distribution of neutrons at the time of measurement can be grasped in real time, and accurate residual life can be diagnosed.

According to the tenth aspect of the present invention, the driving means inserts the measuring means into the reactor during the operation of the reactor and moves the measuring means to a desired measurement position, and the measuring means changes the neutron flux at the moved position. Since the measurement is performed, the neutron irradiation state in the reactor operating state can be surely grasped.

According to the eleventh aspect of the present invention, since a neutron dosimeter for measuring the accumulated amount of low-speed neutrons is further provided, the accumulated amount of low-speed neutrons can be measured in addition to the measurement of the fast or medium-speed neutron flux. You can figure it out.

According to the twelfth aspect of the present invention, the neutron irradiation dose analyzing means calculates the neutron irradiation dose from the neutron flux measured in real time by the measuring means and the accumulated amount of neutrons by the neutron dosimeter. In addition to the measurement of high-speed or medium-speed neutron flux, the accumulation amount of low-speed neutrons can be grasped, which enables accurate analysis of neutron irradiation dose.

According to the thirteenth aspect of the present invention, ⁶³ Cu (n, α) ⁶⁰ Co nuclear reaction, ⁵⁵ Mn (n,
2n) ⁵⁴ Mn nuclear reaction, ⁵⁴ Fe (n, p) ⁵⁴ Mn nuclear reaction,
⁴⁶ Ti (n, p) ⁴⁶ Sc nuclear reaction, ⁵⁸ Ni (n, p) ⁵⁸ C
Since a threshold detector utilizing either the o nuclear reaction or the ³² S (n, p) ⁵² P nuclear reaction is used, fast neutrons can be reliably measured.

According to the fourteenth aspect of the present invention, the measuring means includes a U235Cd filter, Nb93, Ag10.
With 9Cd filter, Co59Cd filter, Ni6
0, Fe54, Ti64, Np237, Ni58, Fe
With 58Cd filter, Sc45Cd filter, Ta1
Since one of the substances with the 81Cd filter and the Pu239Cd filter is used, medium-speed neutrons can be reliably measured.

According to the fifteenth aspect of the present invention, the driving means includes the wire having the measuring means at its tip, the wire that extends vertically inside the reactor, and the movement that extends to the lower portion of the reactor pressure vessel. Type in-core instrumentation device is composed of a wire drive device for advancing and retracting in the guide tube, and a drive control device for positioning the measuring means at an arbitrary measurement position of the core along the cal tube through the wire drive device. By driving the wire, the measuring means can be easily sent to a desired position of the nuclear reactor and collected.

According to the sixteenth aspect of the present invention, the drive control device accommodates the measuring means in the shielded container outside the reactor so that the measurement result of the neutron flux can be recorded. Neutron measurement results can be obtained in a safe state.

According to the seventeenth aspect of the present invention, a neutron dosimeter for measuring the accumulated dose of medium-speed and / or high-speed neutrons is attached when the reactor is shut down, the reactor is restarted, and the reactor is restarted. Since the irradiation amount of neutrons is measured when the neutrons are stopped, accurate residual life can be diagnosed based on the accumulated amount of neutrons over time.

According to the eighteenth aspect of the present invention, the neutron dosimeter is Li6, B10, Ni58, In11.
5, Ta181, Au197, Ag109, Th23
2, U235, Co59, Fe58, Mn55, Cu6
Since any one of 3, Pu239, Na23, Sc45, and Fe54 is used, it is possible to reliably grasp the irradiation dose of neutrons at medium and high speeds.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a nuclear reactor residual life diagnosis apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a main part of a diagnosis unit of a residual life diagnosis device for a nuclear reactor according to an embodiment.

FIG. 3 is a diagram showing a state in which the detector of the reactor residual life diagnosis apparatus according to the embodiment is inserted into a reactor pressure vessel of the reactor.

FIG. 4 is a diagram showing a state in which a neutron dosimeter in the reactor residual life diagnosis apparatus according to the embodiment is provided in a channel fastener guard outside a fuel channel box in the reactor.

5 is a plan view showing the relationship among the fuel channel box, the upper lattice plate, and the neutron dosimeter in FIG. 4. FIG.

FIG. 6 is a view showing a state in which a neutron dosimeter in a nuclear reactor residual life diagnosis apparatus according to another embodiment is provided in a channel fastener outside a fuel channel box in a nuclear reactor.

FIG. 7 is a diagram showing an embodiment in which a neutron dosimeter is provided at a core support plate position of a neutron monitor holder.

FIG. 8 is a diagram showing an example of a pressurized water reactor.

FIG. 9 is a diagram for explaining an example of a boiling water reactor.

FIG. 10 is a partially cutaway perspective view showing an internal structure of a boiling water reactor.

FIG. 11 is a plan view showing the arrangement of neutron monitors in a conventional example.

FIG. 12 is a diagram showing an installation state of a neutron monitor holder in a core in a conventional example.

FIG. 13 is a diagram showing a state in which a stationary neutron flux detector is provided on a neutron monitor holder in a conventional example.

[Explanation of symbols]

 1 Reactor Pressure Vessel 2 Core Shroud 3 Upper Lattice Plate 4 Monitoring Specimen Basket 8 Monitoring Specimen Basket for Accelerated Irradiation 25 Fuel Assembly 28 Neutron Monitor Holder (LPRM) 29 Cal Tube 30 Stationary Neutron Flux Detector 31 Neutron Monitor (IRM / SRM) 33 Fuel assembly 42 Neutron dosimeter 49 TIP guide tube 50 Reactor containment vessel penetration part 51 Isolation valve 52 Remote cutoff valve 53 Shielding container 54 Wire drive device 55 Drive control device 56 Neutron flux measurement device 57 Valve control device 58 neutron flux recorder 61 neutron dosimeter information file 62 core operation data 63 neutron dose analysis device 64 structural material aged deterioration data file 65 structural material aged deterioration prediction evaluation analysis device 66 equipment structure stress analysis device 67 residual life evaluation analysis device 68 Analysis result table Equipment

Claims (18)

[Claims] 1. A remaining life of a nuclear reactor including a reactor pressure vessel, a fuel assembly arranged in the reactor pressure vessel, and an internal structure for holding the fuel assembly in a predetermined position. In the method of diagnosing the remaining life of the reactor to be diagnosed, a measuring means for measuring the neutron flux from the outside of the reactor pressure vessel during the operation of the reactor is inserted, and the vicinity of the measurement site is measured based on the measurement value measured by the measuring means. A method for diagnosing remaining life of a reactor, comprising predicting the state of material deterioration due to neutrons in reactor internals, and diagnosing the remaining life of the reactor based on the predicted state of deterioration. 2. The residual life diagnosis method for a nuclear reactor according to claim 1, wherein the neutron flux is a fast and / or medium speed neutron flux. 3. The method for diagnosing remaining life of a nuclear reactor according to claim 1, wherein the portion into which the measuring means is inserted is near a structure around the fuel assembly. 4. The prediction of the deterioration of the material is performed by obtaining the neutron irradiation dose to the structure from the measurement result and obtaining the aged deterioration characteristic of the structure using the aged deterioration data of the structural material prepared in advance. The method for diagnosing residual life of a nuclear reactor according to claim 1, wherein: 5. The residual life of a nuclear reactor according to claim 1, wherein the diagnosis of the remaining life is performed based on the obtained aging characteristics and stress evaluation data of a measured portion of the reactor internal structure. Life diagnosis method. 6. A remaining life of a nuclear reactor including a reactor pressure vessel, a fuel assembly arranged in the reactor pressure vessel, and an internal structure for holding the fuel assembly in a predetermined position. A method for diagnosing a residual life of a nuclear reactor to be diagnosed, wherein a measuring means for measuring an accumulated dose of medium-speed and / or high-speed neutrons is attached to a structure in a reactor pressure vessel when the reactor is shut down. When the operation is restarted and then stopped again, the measuring means is taken out of the reactor, and the state of deterioration of the material due to neutrons in the reactor internal structure near the measurement site based on the measured values measured by the taken measuring means And a method for diagnosing the remaining life of the reactor based on the predicted deterioration state. 7. The measuring means comprises first measuring means for measuring low-speed neutron flux in the core and second measuring means for measuring high-speed and / or low-speed neutron flux outside the core. The method for diagnosing remaining life of a nuclear reactor according to claim 6, wherein: 8. The method for diagnosing remaining life of a nuclear reactor according to claim 7, wherein the second measuring means is provided in at least one of the startup area monitor holder and the average output area monitor holder. 9. A remaining life of a reactor provided with a reactor pressure vessel, a fuel assembly arranged in the reactor pressure vessel, and an internal structure for holding the fuel assembly in a predetermined position. In the residual life diagnostic device for a reactor to be diagnosed, measuring means for measuring the neutron flux emitted from the fuel assembly and this measuring means are inserted from the outside of the reactor pressure vessel to a desired position inside the reactor pressure vessel. , Set to a desired position, driving means of the measuring means to be extracted from the position after measurement, recording means for recording the neutron flux measured by the measuring means, of the neutron flux recorded in the recording means Neutron dose analysis means for analyzing the neutron dose to the core structure at the measurement position based on the measurement record and the operation record of the reactor, and the neutron dose analyzed by the neutron dose analysis means Predicting the state of deterioration of the al furnace structure, remaining life diagnosis unit of the reactor, characterized in that it comprises a diagnostic means for diagnosing the remaining lifetime of the reactor from the state of the deterioration, the. 10. The driving means inserts the measuring means into the reactor during operation of the reactor and moves the measuring means to a desired measurement position, and the measuring means measures the neutron flux at the moved position. The residual life diagnosing device for a nuclear reactor according to claim 9. 11. The residual life diagnostic apparatus for a nuclear reactor according to claim 9, further comprising a neutron dosimeter which is arranged at a preset position and which measures the accumulated amount of low-speed neutrons. 12. The neutron irradiation dose analyzing means calculates the neutron irradiation dose from the neutron flux measured in real time by the measuring means and the accumulated amount of neutrons by the neutron dosimeter. Reactor Remaining Life Assessment Device 13. The measuring means comprises ⁶³ Cu (n, α) ^60.
Co nuclear reaction, ⁵⁵ Mn (n, 2n) ⁵⁴ Mn nuclear reaction, ⁵⁴ Fe
(N, p) ⁵⁴ Mn nuclear reaction, ⁴⁶ Ti (n, p) ⁴⁶ Sc nuclear reaction, ⁵⁸ Ni (n, p) ⁵⁸ Co nuclear reaction, and ³² S (n,
The residual life diagnosing device for a nuclear reactor according to claim 9, which comprises a threshold detector that utilizes one of p) ⁵² P nuclear reactions. 14. The measuring means includes a U235Cd filter, Nb93, Ag109Cd filter, Co59.
With Cd filter, Ni60, Fe54, Ti64, Np
237, Ni58, Fe58 with Cd filter, Sc45
With Cd filter, Ta181 With Cd filter, Pu23
The residual life analysis and evaluation system for a nuclear reactor according to claim 9, characterized by comprising a neutron flux detector using any of substances with a 9Cd filter. 15. The wire for which the driving means has a measuring means at its tip, a cal tube extending in the vertical direction inside the reactor and a movable in-core instrumentation device guide extending to the lower part of the reactor pressure vessel. The wire drive device for advancing and retracting the inside of the pipe, and a drive control device for positioning the measuring means at an arbitrary measurement position of the core along the cal tube via the wire drive device. Remaining life diagnostic equipment for nuclear reactors. 16. The drive control device is characterized in that the measuring means is housed in a shielding container outside the reactor so that the measurement result of the neutron flux can be recorded by the recording means. Reactor residual life diagnostic device described. 17. A remaining life of a reactor provided with a reactor pressure vessel, a fuel assembly arranged in the reactor pressure vessel, and an internal structure for holding the fuel assembly in a predetermined position. A neutron dosimeter for measuring the accumulated amount of neutrons emitted from a fuel assembly in a reactor residual life diagnostic device for diagnosis, and a set for setting this neutron dosimeter at a preset measurement position during shutdown of the reactor. Means, after restarting the operation of the nuclear reactor, when the neutron dosimeter is taken out of the reactor when restarted, recording means for recording the accumulated amount of measured neutrons, the measurement of the neutron flux recorded in the recording means Neutron dose analysis means for analyzing the neutron dose to the core structure at the measurement position based on the record and the operation record of the reactor, and analyzed by the neutron dose analysis means A residual life diagnosing device for a nuclear reactor, comprising: a diagnosing means for predicting a deterioration state of an internal structure from a neutron irradiation amount and diagnosing a residual life of the reactor from the deterioration state. . 18. The neutron dosimeter is Li6, B
10, Ni58, In115, Ta181, Au19
7, Ag109, Th232, U235, Co59, F
e58, Mn55, Cu63, Pu239, Na23,
18. The residual life diagnosing device for a nuclear reactor according to claim 17, comprising either Sc45 or Fe54.