JP7569269B2 - Control rod insertability evaluation device and control rod insertability evaluation method - Google Patents

Description

The present invention relates to an apparatus and method for evaluating the insertability of control rods in a nuclear reactor in a nuclear power plant.

As an example of seismic testing equipment that can suppress the occurrence of seismic motion caused by vibration during testing, Patent Document 1 describes a test vessel in which mock fuel simulating fuel in a nuclear reactor and control rods are stored inside a vessel filled with water and to which a control rod drive device is attached for inserting the control rod into the mock fuel, a reaction wall installed around the test vessel, a vibrator fixed to the reaction wall and vibrating the test vessel in the horizontal direction, and a load support mechanism and linear slide mechanism that support the test vessel so that the test vessel can reciprocate along the horizontal direction.

JP 2016-8892 A

There is a demand in various fields for evaluating the seismic safety of structures against earthquakes, etc. For example, a series of standards for vibration testing of nuclear power plants in Japan are detailed in the Japan Electric Association Guide (JEAG), which specifies the technologies and technical activities that are considered appropriate to implement in the design, construction, operation, etc., from the perspective of ensuring the safety and reliability of nuclear power plants.

In addition, earthquake-resistant design technology for nuclear equipment is specified in the "Supplement to the Seismic Design Guidelines for Nuclear Power Plants (JEAG4601-1991)" as conforming to the "Seismic Design Guidelines for Nuclear Power Reactor Facilities."

The above-mentioned "JEAG4601-1991" specifies in Appendix 4.4 the method for evaluating the seismic function of control rods. The basic idea behind this evaluation method is that "the dynamic function required of control rods during an earthquake is to be inserted into the reactor core to ensure that the reactor is shut down during an earthquake, and for this purpose, the insertability of control rods during an earthquake must be evaluated."

This type of evaluation needs to be carried out both analytically and experimentally, and seismic test facilities are required to experimentally obtain verification data for the control rods. In other words, seismic test facilities are required that can vibrate the fuel assemblies using a vibrator simulating an earthquake, insert the control rods during this time, and evaluate the time required for insertion, thereby verifying that the control rod insertion function is maintained.

In addition, tests to verify the insertability of control rods when external forces other than earthquakes are applied to the fuel assemblies and cause them to bend are also important.

One example of a device for testing the seismic resistance of the control rod insertion function during an earthquake is disclosed in Patent Document 1. In this technology, multiple mock fuels are stored inside a container filled with liquid, and the test container is equipped with a control rod drive device that inserts control rods between the mock fuels. A heater and a pump are also connected to the test container, which can heat and pressurize the liquid to simulate the temperature and pressure inside a nuclear reactor. Multiple vibrators fixed to the reaction wall are connected to the mock fuel inside the test container via connecting jigs, and the attempt is made to simulate the fuel under conditions close to an actual earthquake.

In the above-mentioned Patent Document 1, a vibration exciter fixed to the reaction wall and a mock fuel assembly inside a heated and pressurized test vessel are connected by a jig.

However, since there are multiple mock fuel assemblies, multiple reaction walls are also required to secure the vibrators, which may increase the cost of testing. In addition, there is an issue that it is technically difficult to realize the structure of the interface between the test vessel and the connection jig that connects the mock fuel assemblies and the vibrators, and improvements are required.

The object of the present invention is to provide a control rod insertability evaluation device and a control rod insertability evaluation method that can easily reproduce tests of the insertability of control rods under conditions that are closer to actual conditions.

The present invention includes multiple means for solving the above problems, and an example of such a device is a control rod insertability evaluation device that simulates a vibration state when a specified seismic motion is input, and is characterized by having a memory unit that stores the elapsed time from the start of an earthquake and the deflection amount of a fuel assembly in correspondence with each other, a deflection amount extraction unit that extracts the deflection amount from the memory unit using the total time between the start of an earthquake and the start of control rod insertion and the elapsed time from the start of control rod insertion, a friction force memory unit that stores the movement distance of the control rod from the start of insertion, the deflection amount, and the friction force applied to the control rod in correspondence with each other, a friction force extraction unit that extracts a friction force from the friction force memory unit using the movement distance of the control rod from the start of insertion and the deflection amount extracted by the deflection amount extraction unit, and a friction force application unit that applies the friction force extracted by the friction force extraction unit to the control rod.

According to the present invention, it is possible to easily reproduce the test of the insertability of the control rod under conditions that are closer to the actual conditions. The problems, configurations, and effects other than those described above will become clear from the explanation of the following examples.

1 is an overall schematic diagram of a control rod insertability evaluation device according to a first embodiment of the present invention. This is a cross-sectional view taken along the line A-A' in Figure 1. FIG. 2 is a diagram showing an outline of the functional configuration of the control rod insertability evaluation device of the first embodiment and an outline of frictional force application. FIG. 4 is a diagram showing an example of a display screen for displaying test results of the control rod insertability evaluation device according to the first embodiment. FIG. 13 is a diagram showing an example of a display screen displaying a test result graph of the control rod insertability evaluation device according to the first embodiment. FIG. 13 is a diagram showing an example of a display screen for displaying a test result judgment of the control rod insertability evaluation device according to the first embodiment. FIG. 1 is a diagram showing an overview of a control rod insertability evaluation device according to a second embodiment of the present invention and an overview of frictional force application. FIG. 11 is a diagram showing an overview of a control rod insertability evaluation device according to a third embodiment of the present invention, and an overview of frictional force application.

Below, an embodiment of the control rod insertability evaluation device and control rod insertability evaluation method of the present invention will be described with reference to the drawings.

In addition, in the drawings used in this specification, identical or corresponding components are given the same or similar reference numerals, and repeated explanations of these components may be omitted.

Example 1
A control rod insertability evaluation device and a control rod insertability evaluation method according to a first embodiment of the present invention will be described with reference to FIGS.

First, the overall configuration of the control rod insertability evaluation device will be described with reference to Figures 1 and 2. Figure 1 is an overall schematic diagram of the control rod insertability evaluation device according to the first embodiment, and Figure 2 is a cross-sectional view of the A-A' section in Figure 1.

The control rod insertability evaluation device 1 shown in FIG. 1 etc. is a device for evaluating the insertability of a control rod 201 by simulating the vibration state when a specified seismic motion is input, and can evaluate the scram time.

The reactors to be evaluated are primarily boiling water reactors, but the boiling water reactors to be evaluated are preferably ABWRs or newer generation BWRs. However, the boiling water reactors to be evaluated may also be BWRs of the generation before ABWRs, and the evaluation is not limited to boiling water reactors, and can also be suitably applied to other types of reactors, such as PWRs.

As shown in Figures 1 and 2, the control rod insertability evaluation device 1 includes a control rod 201, a piston 202, a test vessel 203, a heater 204, a pump 205, a control rod drive system 206, water 207, a control rod guide tube cover 208, a control rod guide tube 209, piping 210, a drive source 211, a treatment device 212, a cross-shaped groove 301, a plate 302, a connection jig 303, etc.

The test vessel 203 contains the control rod 201, piston 202, control rod guide tube 209, etc. A control rod drive system 206 is attached to the bottom of the test vessel 203 for driving the control rod 201 vertically upward to the top of the test vessel 203. Although not shown for convenience of illustration, multiple observation windows are provided inside the test vessel 203 for attaching sensors for observing and measuring the control rod 201, etc.

The test vessel 203 is filled with water 207 that simulates the temperature and pressure inside a nuclear reactor in order to reproduce the same environment as an actual nuclear reactor. This water 207 is heated by a heater 204 connected to the test vessel 203 and pressurized by a pump 205, simulating the temperature (approximately 300°C) and pressure (approximately 7 MPa) inside a nuclear reactor. By simulating the temperature and pressure inside a nuclear reactor in this way, it is possible to simulate conditions that are closer to those in an actual machine, improving evaluation accuracy and enabling tests to be conducted to enhance safety.

As shown in FIG. 2, a control rod guide tube cover 208 is installed on the top of the control rod guide tube 209, and a piston 202 for applying a frictional force to the control rod 201 is fixed to the top of the control rod guide tube cover 208.

The control rod guide tube cover 208 has a cross-shaped groove 301 where the control rod 201 is inserted to simulate a fuel assembly support bracket. Eight pistons 202 are arranged in the control rod guide tube cover 208 in a direction that allows them to reciprocate perpendicular to the surface of the control rod 201.

The pistons 202 are connected to the plates 302 that contact the control rod 201 by connecting jigs 303, and are members that press the plates 302 perpendicularly against the control rod 201. The reciprocating motion of the pistons 202 makes it possible to press the plates 302 against the surface of the control rod 201. The pistons 202 correspond to the frictional force imparting unit 108 shown in FIG. 3.

When the control rod 201 is inserted, the piston 202 presses the plate 302 against the control rod 201, generating a frictional force against the control rod 201. By controlling this frictional force, the insertion resistance that occurs when the control rod 201 is inserted between the deflected fuel assemblies is simulated. The plate 302 may be made of a metal material or a resin material such as rubber, and there are no restrictions on its material.

Piston 202 is connected to a driving source 211 for piston 202 and pipes 210a, 210b, 210c, and 210d that supply power from driving source 211 to piston 202. In the following, when there is no need to distinguish between each of pipes 210a, 210b, 210c, and 210d, the subscripts (a, b, c, and d) will be omitted (the same applies to the subscripts of other components).

The piping 210 passes through a path that does not interfere with the insertion of the control rod 201, and is connected to the driving source 211 (see Figure 1). By applying frictional force with the piston 202, there is no need to vibrate the mock fuel assembly with a vibrator or the like installed outside the test vessel 203, and as a result, there is no need to connect it to the test vessel, which makes it possible to reduce test costs. In addition, the elimination of the need for a mock fuel assembly also reduces test costs. The driving source 211 may be pressure, such as hydraulic or pneumatic pressure, or may be electricity. The driving source 211 is connected to a processing device 212 that controls the power.

Next, the processing performed by the processing device 212 in FIG. 1 and the functional configuration of the control rod insertability evaluation device will be explained using FIG. 3. FIG. 3 is a diagram showing an outline of the functional configuration of the control rod insertability evaluation device and an outline of the application of friction force.

The processing device 212 is a device that outputs frictional forces simulating the insertion resistance that the control rod receives from the fuel assembly when a scram occurs during an earthquake, and processes and displays the results of the evaluation of the insertability, and is composed of a computer. The processing device 212 is equipped with general computer hardware such as a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), SSD (Solid State Drive) or HDD (Hard Disk Drive), and a display. The SSD etc. stores an OS (Operating System), application programs, various data, etc. The OS and application programs are deployed in the RAM and executed by the CPU.

As shown in FIG. 3, the processing device 212 has, as its functional configuration, an insertion time recording unit 102, an acquired data storage unit 111, a comparison evaluation unit 112, a display unit 113, a storage unit 105, a drawer unit 104, a friction force storage unit 106, a friction force drawer unit 107, etc.

The control rod travel distance acquisition unit 103 is a part that records and acquires the operation instruction amount of the control rod drive system 206, and outputs the acquired information to the acquired data storage unit 111. Note that the control rod travel distance acquisition unit 103 may be in a form that directly measures the drive distance of the control rod 201 with a sensor, in which case it will not be a component within the processing device 212.

The insertion elapsed time recording unit 102 acquires the elapsed time from the start of insertion in the control rod insertion unit 101 immediately before the start of control rod insertion by acquiring the operation instruction timing to the control rod drive system 206. The acquired elapsed time information is output to the acquired data storage unit 111. Note that if the control rod movement distance acquisition unit 103 is used as a center that directly detects the operation of the control rod 201, the control rod movement distance acquisition unit 103 can also function as the insertion elapsed time recording unit 102 by detecting the operation start timing.

The acquired data storage unit 111 is a part that stores the information acquired by the control rod travel distance acquisition unit 103 and the insertion elapsed time recording unit 102, and is preferably configured with the SSD or HDD described above.

The comparison evaluation unit 112 compares the scram time from the start to the end of the insertion of the control rod 201 with a design threshold, and judges it as pass if the scram time is below the design threshold, and as fail if the scram time is equal to or greater than the design threshold. Alternatively, it may be judged as pass if the entire length of the control rod 201 that should be inserted is normally inserted at the end of the insertion, and as fail if less than the length that should be inserted is inserted at the end of the insertion. The judgment result by the comparison evaluation unit 112 is output to the display unit 113.

The display unit 113 is a device that displays the evaluation results in the comparative evaluation unit 112, and corresponds to the display described above. This screen displays various results shown in Figures 4, 5, and 6, which will be described later. The details of these will be described later.

The memory unit 105 is a storage device that stores the time history of the deflection of the fuel assembly in response to a specified seismic motion, i.e., the time elapsed since the start of the earthquake and the deflection of the fuel assembly in correspondence with each other, and is configured as an SSD or HDD, similar to the acquired data memory unit 111 described above.

The extraction unit 104 is the part that extracts the deflection amount of the fuel assembly at the corresponding timing from the memory unit 105 using the total time between the start of the earthquake and the start of the insertion of the control rod 201 and the elapsed time from the start of the insertion of the control rod 201 input from the insertion elapsed time recording unit 102, and is the main part that executes the deflection amount extraction step.

The frictional force memory unit 106 is a device that stores three pieces of information in association with each other: the travel distance of the control rod 201 from the start of insertion, the amount of deflection of the fuel assembly, and the frictional force acting as the insertion resistance on the control rod 201 at that amount of deflection and position. Like the memory unit 105 and acquired data memory unit 111 described above, the frictional force memory unit 106 is preferably configured as an SSD or HDD.

The amount of deflection of the fuel assembly stored in the memory unit 105 can be expressed as two physical quantities expressed two-dimensionally using Cartesian coordinates or polar coordinates, but it may also be expressed one-dimensionally as the distance from the central axis of the fuel assembly.

Correspondingly, the method of expressing the deflection amount of the fuel assembly stored in the frictional force memory unit 106 is determined, and the deflection amount of the fuel assembly stored in the frictional force memory unit 106 can be expressed as two physical quantities expressed in two dimensions.

The information stored in the memory unit 105 and the frictional force memory unit 106 may be obtained analytically or experimentally.

The friction force extraction unit 107 is a part that extracts the friction force from the friction force memory unit 106 at the corresponding timing using the movement distance of the control rod 201 from the start of insertion input from the control rod movement distance acquisition unit 103 and the deflection amount extracted by the extraction unit 104, and is the main entity that executes the friction force extraction step. The friction force extraction unit 107 outputs information on the value obtained by dividing the extracted friction force by the number of pistons 202 and the friction coefficient of the plate 302 to the drive source 211.

The driving source 211 controls the piston 202 to press the plate 302 against the control rod 201 using the frictional force derived in the frictional force extraction section 107 of the processing device 212.

The frictional force applying unit 108 is a device that is driven by the driving source 211 and applies the frictional force extracted by the frictional force extracting unit 107 to the control rod 201, and is the main body that executes the frictional force applying step. As described above, this frictional force applying unit 108 corresponds to the piston 202, and applies a frictional force to the control rod 201.

The frictional force applying unit 108 can be configured to apply a frictional force that changes over time, but it may also apply a constant frictional force regardless of the passage of time.

In this state, the control rod 201 begins to be inserted by the control rod insertion section 101, which corresponds to the control rod drive system 206, and an evaluation of the insertability of the control rod 201 in a specified seismic motion is performed.

First, immediately before the start of control rod insertion, the control rod insertion section 101 records the elapsed time from the start of insertion in the insertion elapsed time recording section 102, and the movement distance of the control rod 201 from its initial position is acquired by the control rod movement distance acquisition section 103.

The amount of deflection of the fuel assembly corresponding to the total time, calculated from the time history memory unit 105 for the amount of deflection of the fuel assembly, is extracted by the extraction unit 104 using the total time between the start of the earthquake and the start of control rod insertion and the time elapsed since the start of insertion (deflection amount extraction step).

The amount of deflection of the pulled-out fuel assembly and the travel distance of the control rod 201 are used to refer to the frictional force memory unit 106, and the frictional force at the corresponding time is extracted by the frictional force extraction unit 107 (frictional force extraction step).

The extracted frictional force is applied to the control rod 201 by the frictional force applying unit 108 (frictional force applying step). The frictional force is applied from the processing device 212 via the driving source 211.

The above series of steps are carried out in the processing device 212 continuously from immediately after the start of insertion until the end of insertion, during which time the frictional force exerted by the piston 202 on the control rod 201 is controlled.

The completion of insertion may be determined based on the timing at which the movement distance acquired by the control rod movement distance acquisition unit 103 is determined to exceed a predetermined threshold, or may be determined as a direct detection result by a sensor installed at the insertion completion position of the control rod 201.

Next, examples of the display of the evaluation result screen in the control rod insertability evaluation device 1 will be described with reference to Figures 4 to 6. Figure 4 shows an example of a display screen that displays the test results, Figure 5 shows an example of a display screen that displays a test result graph, and Figure 6 shows an example of a display screen that displays the judgment results of the test result judgment unit.

Figure 4 is a screen that displays the data obtained from the test results displayed on the display unit 113. A table 402 displays the elapsed time 403 from the start of insertion, the control rod travel distance data at that time 404, the frictional force 405 extracted from the frictional force memory unit 106 by the frictional force extraction unit 107, and the numerical values of the frictional force 406 applied to the control rod 201 by the frictional force application unit 108.

By recording both the extracted frictional force and the applied frictional force, it is possible to monitor whether the frictional force introduced by the processing device 212 is being accurately input to the control rod 201.

Figure 5 is a screen in which table 402 in Figure 4 displayed on display unit 113 has been graphed. Graph 501 shows the data for each time shown in table 402 as a time history graph, with each piece of data displayed in the form of vertical axes 502a, 502b, 502c, horizontal axes 504a, 504b, 504c, and graphs 503a, 503b, 503c.

The table 402 shown in FIG. 4 and the graph 501 shown in FIG. 5 may be updated from moment to moment, or the data from the start of insertion to the completion of insertion may be recorded and displayed together immediately after the completion of insertion. By displaying a graph as in FIG. 5, the time progression of the test data can be seen at a glance, and the examiner can quickly determine whether any problems have occurred in the test.

It is desirable to set the time step width of the data to a minimum that is equal to the sampling period of the measuring device that measures the control rod travel distance.

The display items shown in the example on the monitoring screen are the minimum necessary, and in addition to these, the temperature and pressure inside the test vessel 203 may be monitored and displayed, and the amount of deflection of the fuel assembly retrieved from the memory unit 105 may be recorded and displayed.

Figure 6 shows a screen displaying the scrum time evaluation results displayed on the display unit 113, with a table 601 displaying a design guideline value display area 602, a scrum time display area 603, and a judgment result display area 604.

If the scram time falls within the design target value, pass is displayed in the judgment column. The design target value is input in advance into the processing device 212, and the scram time is displayed as the time from the start of the insertion of the control rod 201 to its completion. The travel distance of the control rod 201 at which insertion is complete is input in advance into the processing device 212, and the time at which this travel distance is reached is determined as the time at which the control rod 201 reaches this travel distance.

Next, we will explain the effects of this embodiment.

The control rod insertability evaluation device 1 of the first embodiment of the present invention described above is a device that simulates a vibration state when a predetermined seismic motion is input, and includes a memory unit 105 that stores the elapsed time from the start of the earthquake and the deflection amount of the fuel assembly in correspondence with each other, an extracting unit 104 that extracts the deflection amount from the memory unit 105 using the total time between the start of the earthquake and the start of the insertion of the control rod 201 and the elapsed time from the start of the insertion of the control rod 201, a friction force memory unit 106 that stores the movement distance of the control rod 201 from the start of insertion, the deflection amount, and the friction force applied to the control rod 201 in correspondence with each other, a friction force extracting unit 107 that extracts the friction force from the friction force memory unit 106 using the movement distance of the control rod 201 from the start of insertion and the deflection amount extracted by the extracting unit 104, and a friction force applying unit 108 that applies the friction force extracted by the friction force extracting unit 107 to the control rod 201.

This makes it possible to reproduce the deflection of the fuel assembly, which is a hindrance to the insertion of the control rod 201, without using a vibrator, and makes it easier than ever to carry out tests to evaluate the scram time during an earthquake that simulates the temperature and pressure inside the reactor (control rod insertability). In addition, because it is not necessary to use a vibrator, it also has the effect of reducing the manufacturing costs of the test equipment.

The system further includes a test vessel 203 filled with water 207 that simulates the temperature and pressure inside a nuclear reactor and in which a control rod 201 and a frictional force imparting unit 108 are housed. The test vessel 203 has a control rod drive system 206 that drives the control rod 201 vertically, a heater 204 that heats the water 207, and a pump 205 that pressurizes the inside of the test vessel 203. This makes it possible to easily reproduce the temperature and pressure inside a nuclear reactor, thereby further improving the evaluation accuracy and enabling tests to be carried out to further enhance safety.

Furthermore, since the deflection amount stored in the memory unit 105 is two physical quantities expressed in two dimensions, and the deflection amount of the fuel assembly stored in the friction force memory unit 106 is two physical quantities expressed in two dimensions, the deflection of the fuel assembly can be expressed more precisely, and it becomes easier to perform an insertability evaluation under conditions closer to those of the actual machine.

The device further includes a display unit 113 that displays the evaluation results. In particular, the display unit 113 displays the elapsed time, the distance traveled, the frictional force extracted from the frictional force memory unit 106, and the frictional force applied by the frictional force application unit 108, making it easier to understand the evaluation results.

Furthermore, by further providing a comparison evaluation unit 112 that compares the scram time from the start to the end of the insertion of the control rod 201 with a design threshold, and judges it as pass if the scram time is below the design threshold, and as fail if the scram time is equal to or greater than the design threshold, evaluation of the insertability becomes easier.

The frictional force applying unit 108 also has a plate 302 that contacts the control rod 201 and a piston 202 that presses the plate 302 perpendicularly against the control rod 201, and further includes a drive source 211 for the piston 202 and a pipe 210 that supplies power from the drive source 211 to the piston 202. This allows for a simple structure to be realized that generates a force that acts as a resistance to insertion and is applied to the control rod 201 when the fuel assembly is deflected.

Furthermore, the frictional force applying unit 108 can vary the applied frictional force over time, making it possible to perform testing under conditions closer to those that would occur if deformation were caused by actual earthquake motion.

Example 2
The control rod insertability evaluation device and the control rod insertability evaluation method according to the second embodiment of the present invention will be described with reference to Fig. 7. Fig. 7 is a diagram showing an outline of the control rod insertability evaluation device according to the second embodiment and an outline of frictional force application.

As shown in Figure 7, the control rod insertion evaluation device 1A of this embodiment has the same basic configuration as in Example 1, but is a test device for when there are multiple structural proposals for the fuel assembly.

If the structure of the fuel assembly is different, the amount of deflection and its time history will also be different. Therefore, in the control rod insertability evaluation device 1A of this embodiment, the amount of deflection of fuel assemblies with different structures is stored in advance.

As shown in FIG. 7, in the processing device 212A of this embodiment 2, the fuel assembly deflection amount information 703, 704 stored in the memory unit 105A is assigned a different label for each fuel assembly structure.

Similarly, the amount of deflection of the fuel assembly stored in frictional force memory unit 106A and the frictional force that acts as the insertion resistance corresponding to that amount of deflection and the travel distance of the control rod also differ depending on the structure of the fuel assembly, so that the labeling is the same as that of memory unit 105A, the frictional force information 701 and 702 stored in frictional force memory unit 106A is given the same label as the label for each structure of the fuel assembly.

Figure 7 shows the case where there are two types of labels, but there may be three or more types of fuel assembly structures, in which case this can be accommodated by increasing the number of labelings.

When the test is performed, the labeling of the values retrieved from the memory unit 105A and the friction force memory unit 106A from the start to the end of one insertion is the same, and the labeling can be changed for each insertion test.

The rest of the configuration and operation are substantially the same as those of the control rod insertability evaluation device and control rod insertability evaluation method of the first embodiment described above, and details are omitted.

The control rod insertability evaluation device and control rod insertability evaluation method of the second embodiment of the present invention also provide substantially the same effects as those of the control rod insertability evaluation device and control rod insertability evaluation method of the first embodiment described above.

In addition, the deflection amounts stored in memory unit 105A are labeled differently for each fuel assembly structure, and the frictional forces stored in frictional force memory unit 106A are labeled with the same labels as those for each fuel assembly structure, making it possible to test multiple fuel assembly structures with one testing device, and providing an evaluation device and evaluation method that can handle testing under a variety of conditions. Therefore, there is no need to prepare mock fuel assemblies with different structures, and there is no need to replace the mock fuel assemblies for each test, which reduces testing costs and shortens the time required for testing.

Example 3
The control rod insertability evaluation device and the control rod insertability evaluation method according to the third embodiment of the present invention will be described with reference to Fig. 8. Fig. 8 is a diagram showing an outline of the control rod insertability evaluation device according to the third embodiment and an outline of frictional force application.

As shown in FIG. 8, the control rod insertability evaluation device 1B of this embodiment has the same basic configuration as in embodiment 1, but in this embodiment, seismic margin is also taken into consideration.

As shown in FIG. 8, the processing device 212B further includes a seismic margin adding unit 801 that adds a seismic margin to the frictional force extracted by the frictional force extracting unit 107. The seismic margin can be added by multiplying the frictional force by a coefficient or by using a calculation formula.

The frictional force applying unit 108 also applies a frictional force with seismic tolerance added to the control rod 201.

The rest of the configuration and operation are substantially the same as those of the control rod insertability evaluation device and control rod insertability evaluation method of the first embodiment described above, and details are omitted.

The control rod insertability evaluation device and control rod insertability evaluation method of the third embodiment of the present invention also provide substantially the same effects as those of the control rod insertability evaluation device and control rod insertability evaluation method of the first embodiment described above.

The system further includes a seismic margin adding section 801 that adds a seismic margin to the frictional force extracted from the frictional force extraction section 107. The frictional force applying section 108 applies a frictional force with a seismic margin added to the control rod 201, so that an insertion resistance greater than that of the actual device is applied to the control rod 201, and this has the effect of making it possible to perform safety tests in addition to evaluating the insertability.

The seismic margin adding unit 801 of this embodiment can also be applied to the control rod insertability evaluation device 1A of embodiment 2.

＜Other＞
It should be noted that the embodiments described above are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these embodiments. In other words, the present invention can be implemented in various forms without departing from its technical concept or main features.

1, 1A, 1B... Control rod insertability evaluation device 101... Control rod insertion section 102... Insertion elapsed time recording section 103... Control rod movement distance acquisition section 104... Pull-out section (deflection amount pull-out section)
105, 105A...Memory unit 106, 106A...Frictional force memory unit 107...Frictional force extraction unit 108...Frictional force application unit 111...Acquired data memory unit 112...Comparative evaluation unit 113...Display unit 201...Control rod 202...Piston 203...Test vessel 204...Heater 205...Pump 206...Control rod drive system (control rod drive device)
207...Water (liquid)
208...Control rod guide tube cover 209...Control rod guide tube 210, 210a, 210b, 210c, 210d...Pipe 211...Drive source 212, 212A, 212B...Processing device 301...Cross-shaped groove 302...Plate 303...Connection jig 402...Table 403...Elapsed time 404...Movement distance data 405...Friction force 406...Friction force 501...Graph 502a, 502b, 502c...Vertical axis 503a, 503b, 503c...Graph 504a, 504b, 504c...Horizontal axis 601...Table 602...Design guideline value display area 603...Scram time display area 604...Judgment result display area 701, 702...Friction force information 703, 704...Deflection amount information 801...Seismic margin addition section

Claims (13)

A control rod insertability evaluation device that simulates a vibration state when a predetermined seismic motion is input,
a memory unit that stores the amount of deflection of the fuel assembly in correspondence with the time elapsed since the start of the earthquake;
a deflection amount retrieval unit that retrieves the deflection amount from the memory unit using a total time of the time from the start of the earthquake to the start of the insertion of the control rod and the elapsed time from the start of the insertion of the control rod;
a friction force storage unit that stores a movement distance of the control rod from the start of insertion, the deflection amount, and a friction force applied to the control rod in a corresponding manner;
a friction force extracting unit that extracts a friction force from the friction force memory unit by using a moving distance of the control rod from the start of insertion and the deflection amount extracted by the deflection amount extracting unit;
a friction force applying portion that applies the friction force extracted from the friction force extracting portion to the control rod. In the control rod insertability evaluation device according to claim 1,
A test vessel is further provided which is filled with a liquid simulating the temperature and pressure in a nuclear reactor and contains the control rod and the friction force applying portion,
The test vessel comprises:
a control rod drive mechanism that drives the control rod in a vertical direction;
A heater for heating the liquid;
and a pump for pressurizing the inside of the test vessel. In the control rod insertability evaluation device according to claim 1,
The control rod insertability evaluation device, wherein the deflection amounts stored in the memory unit are two physical quantities expressed two-dimensionally. In the control rod insertability evaluation device according to claim 3,
the deflection amounts stored in the frictional force storage unit are two physical quantities expressed two-dimensionally. In the control rod insertability evaluation device according to claim 1,
The control rod insertability evaluation device further comprises a display unit that displays an evaluation result. The control rod insertability evaluation device according to claim 5,
the display unit displays the elapsed time, the moving distance, the frictional force retrieved from the frictional force memory unit, and the frictional force applied by the frictional force application unit. In the control rod insertability evaluation device according to claim 1,
a comparison evaluation unit that compares a scram time from the start of insertion of the control rod to the end of insertion with a design threshold, and judges the control rod to be pass when the scram time is below the design threshold, and judges the control rod to be fail when the scram time is equal to or greater than the design threshold. In the control rod insertability evaluation device according to claim 1,
The deflection amount stored in the memory unit is assigned a different label for each structure of the fuel assembly,
the frictional force stored in the frictional force storage unit is given a label identical to the label for each structure of the fuel assembly. In the control rod insertability evaluation device according to claim 1,
a margin adding section that adds a seismic margin to the frictional force drawn out from the frictional force drawing section,
The control rod insertability evaluation device, wherein the frictional force applying unit applies a frictional force to which a seismic tolerance is added to the control rod. In the control rod insertability evaluation device according to claim 1,
The frictional force applying portion has a plate that contacts the control rod and a piston that presses the plate perpendicularly against the control rod,
A power source for the piston; and
a supply pipe for supplying power from the power source to the piston. In the control rod insertability evaluation device according to claim 1,
The control rod insertability evaluation device, wherein the frictional force applying unit changes the frictional force applied over time. In the control rod insertability evaluation device according to claim 1,
The control rod insertability evaluation device is characterized in that the reactor in which the control rod insertability is evaluated is an ABWR or a new generation BWR subsequent to the ABWR. A method for evaluating control rod insertability, which simulates a vibration state when a predetermined seismic motion is input,
a deflection amount calculation step of calculating a deflection amount of the fuel assembly based on a total time between the start of the earthquake and the start of the insertion of the control rod when the control rod is inserted into the reactor core, and a time elapsed since the start of the insertion of the control rod;
a friction force extraction step of determining a friction force to be applied to the control rod based on a moving distance of the control rod from the start of insertion and the deflection amount extracted in the deflection amount extraction step;
a friction force applying step of applying the friction force extracted in the friction force extracting step to the control rod.

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