JP5032154B2 - Transient fuel health evaluation system and transient fuel health evaluation method - Google Patents

Description

  The present invention relates to a system and method for assessing transient fuel integrity in a boiling water reactor core.

  In the analysis of abnormal transient changes during operation of a conventional boiling water reactor (BWR), the average behavior of the core is evaluated after making severe assumptions, and then the minimum is targeted for thermally demanding high-power bundles. The critical power ratio (MCPR) is being evaluated. In other words, the MCPR evaluation simulates the most severe single channel in the core, and divides this into multiple nodes in one dimension in the axial direction of the flow direction, and applies the heat conduction equation only in the radial direction to the fuel rod for each node. Calculate the heat transfer to the coolant. Evaluation is made with a single-channel thermo-hydraulic analysis code that calculates thermo-hydraulic behavior by applying the law of conservation of mass, momentum and energy to the coolant in the channel (Non-Patent Document 1).

  As a result, for example, an improved boiling water reactor (ABWR) plant has an MCPR operating limit of 9x9 fuel under severe operating conditions of rated 102% power and 90% core flow. It is evaluated as 1.22. The MCPR for this single high-power bundle is a constraint for “abnormal transient changes during operation”. In addition, the current BWR does not take into account the increase in temperature of the cladding tube at the time of transition, and the safety limit output ratio (SLMCPR), which is the limit value, does not fall below the MCPR even when the change at the time of transition is taken into account. (MCPR> SLMCPR = 1.07). That is, one of the criteria for determining “abnormal transient change during operation” is that the minimum limit output ratio (MCPR) is an allowable limit value of 1.07 or more (Non-Patent Document 1).

  However, the recent development of computer environment and the development of simulation calculation code based on it, or the spread of computer networks represented by the Internet, there is a method to evaluate the fuel health at the time of transition more quickly and accurately. Proposed.

  For example, on the regulatory side, temporary BT (boiling transition) during the BWR transition is based on the high accuracy of the simulation calculation code and a lot of knowledge about the effect of the boiling transition phenomenon on the fuel health under the BWR operating conditions. (Non-Patent Document 2) has been established regarding the fuel integrity and non-patent literature 2 regarding the evaluation of fuel reuse that has experienced boiling transition, and part of it has been approved by the Nuclear Safety Commission as a post-BT (boiling transition) standard (Non-Patent Document 3).

  In response to the development of the computer environment and the spread of computer networks, several conceptual technologies related to fuel integrity assessment systems during transition have been proposed.

  For example, if abnormal transients are detected, the nuclear thermal hydraulic performance calculation of the core is performed, and if the occurrence of dryout on the fuel rod surface is predicted, the cladding surface temperature calculation is performed to evaluate the fuel integrity. A system-related technology is known (Patent Document 1). In this technology, there is no provision regarding the use of the network or the collection of plant data.

  Alternatively, instead of detailed three-dimensional calculation, a boiling transition occurrence determination criterion is created in advance, and data on the actual plant operation state is collected to determine boiling transition occurrence, cladding tube surface temperature, and boiling transition duration. A technique for monitoring time is known (Patent Document 2). This technology does not describe how to create a criterion or how to collect data collection means.

  Monitors the thermal characteristics of the fuel assembly, which is predicted to be thermally severe on the core management system, from plant data such as the core management system and nuclear instrumentation signals, and issues an alarm if the limit value is exceeded Is known (Patent Document 3). This is for the purpose of monitoring the pulling out of the control rod at the time of start-up and shortening the time for pattern adjustment.

  A technology is known for deriving a boiling transition generation fuel rod number curve considering data uncertainty from the critical heat flux correlation equation, and issuing a warning about thermal margin by comparing it with the actual operating range (Patent Literature) 4). Here, there is a description that the curve is created from the three-dimensional nuclear thermal hydraulic calculation and the uncertainty of the correlation equation, but there is no description of a detailed procedure or a specific determination example.

  Similarly, with regard to the pressurized water nuclear power reactor (PWR), correlation equations between the cladding tube surface temperature and parameters such as the core inlet temperature and core power are obtained in advance, and these plant data in real time are sequentially converted into correlation equations. There is also a technique for inputting and monitoring the surface temperature of the cladding tube (Patent Document 5). However, there is no description regarding a specific example of the correlation formula, a specific example of creating the correlation formula, and a specific example of monitoring.

  As for the computer network, there is a calculation load and the analysis provider who is equipped with detailed analysis software and the computer of the plant user who requests the analysis on site are connected to each other on the network. There is a technology (Patent Document 6) related to a system that sends an analysis request and the plant data from and sends the analysis result back to the requester when the analysis is completed. Here, using a request as a trigger, process data collection, online data input, analysis execution along with unique data, transfer function by encryption, plant data erasure function after analysis, etc. are realized via a communication network. Yes. The purpose of this technology is to effectively utilize hardware resources and software resources through network cooperation, but there is no specific description of criteria for triggering, means for cooperation, means for encryption, means for transfer, and the like.

  When calculating the minimum critical heat flux ratio (thermal operation limit value) during operation, the safety limits are not set in advance as in the past, but the event and plant parameters are not detected for multiple abnormal events. In consideration of determinism, there is a technique (Patent Document 7) for obtaining a probability distribution and its reliability from a large number of trial simulation results to obtain a minimum operating heat flux ratio. It is related, not related to monitoring.

  There is a technique (Patent Document 8) that periodically performs transient analysis using the latest plant information and obtains a margin for the thermal limit value under conditions based on the actual plant state. Or, the merit of concrete monitoring such as operation and design reflected by conservative evaluation is not clear.

  As a supplement to this technology, fuel rods that may undergo boiling transitions, their axial positions, etc. by performing transient analysis simulating all fuel assemblies in the core using plant measurement data as boundary conditions Is known, and a technique for ensuring the fuel integrity of the core and supporting an appropriate operation procedure is known (Patent Document 9).

  In addition, a technique is known that uses plant data converted into an XML format that reflects the structure of plant data and XSLT procedures in which the conversion procedure is standardized for cooperation between applications in a computer network ( Patent Document 10).

As described above, in the conventional technology, based on the condition that “the temperature of the cladding tube does not rise during transient”, which is one of the criteria for “abnormal transient change during operation”, the accurate core output is based. In many cases, a transient core simulator is used to evaluate the MCPR from the limit output correlation formula. The content to be linked on the network is increasing, but there are few specific procedures and their effectiveness.
JP 2004-301585 A JP 2005-172749 A JP 2003-172792 A JP 2001-99976 A JP 9-61582 A JP 2005-172750 A JP 2002-257993 A Japanese Patent Laid-Open No. 10-2987 JP 2005-283269 A JP 2005-250770 A Kashiwazaki-Kariwa Nuclear Power Station Reactor Installation Change Application (Expansion of No. 6 and 7 reactors) Evaluation criteria for fuel integrity after transient boiling transition in BWR: 2003, June 2003, Japan Atomic Energy Society Report of the Subcommittee on Fuel Integrity after Boiling Transition Nuclear Safety Committee Nuclear Safety Standards / Guidelines Special Committee May 19, 2006

  The MCPR and fuel integrity evaluation system for the “abnormal transient change during operation” described above does not assume that the temperature of the fuel cladding tube rises during the transient change. Recently, however, there is a direction to introduce a post-BT standard that allows a temporary increase in the temperature of the fuel cladding during “abnormal transient changes during operation”, and part of this standard has been approved by the Nuclear Safety Commission. Therefore, an evaluation method to replace the MCPR and fuel integrity evaluation system for the current “abnormal transient change during operation” is required. However, at present, the criteria for reusing fuel assemblies that have experienced transient boiling are out of the scope of the review, but when the criteria become applicable, whether the criteria are met or not. An evaluation method that can determine the above is required.

  As shown in FIG. 17, the post BT criterion indicates a criterion for determining fuel integrity and reusing the fuel assembly based on the temperature of the fuel cladding tube and the duration of dryout. Thus, in the future, in the introduction of the post-BT standard that allows a temporary increase in the temperature of the fuel cladding tube at the time of “abnormal transient change during operation”, from the determination of fuel reuse, BT bundle, BT rod, BT position, BT Evaluation of time and PCT (maximum cladding tube temperature) is important.

  That is, in the analysis of “abnormal transient change during operation”, it is evaluated which fuel rod has experienced BT over which period, and what is the maximum value of the fuel rod cladding tube temperature at that time. Are important, but these are insufficient with the prior art. Further, the conventional technology has problems such as not evaluating the CPR change of all the bundles and not considering the feedback of the core three-dimensional power distribution and the hydrothermal state in the bundle at the time of transient change.

  The present invention has been made in order to solve the above-described problems. When an abnormal transient change occurs during operation in a boiling water reactor, or when some fuel integrity evaluation is required, the core The purpose of this study is to enable quick analysis of nuclear thermal and hydraulic dynamics.

In order to achieve the above object, the transient fuel integrity evaluation system according to the present invention evaluates the transient behavior of a boiling water reactor plant by simulating nuclear thermal hydraulic characteristics of the core of a boiling water reactor. A possible plant dynamics simulator, a core management system that monitors and manages the state of the core, a process management system that monitors and manages the process volume based on the measurement data of the boiling water reactor plant, and a boiling water reactor A transient phenomenon management system that records and manages transient measurement data of a plant, a data linkage management means that links these systems through a network, and performs data transfer and processing necessary for linkage, plant measurement data, and a simulator Database management means for managing input data and simulation results, and data input / output to the user A transient fuel integrity evaluation system comprising a chromatography Heather interface means, and data handled by the data linkage management means, and operation-dependent part dependent on the operating state of the boiling water reactor plant, a boiling water It is separated into an operation-independent part that does not depend on the operating state of the nuclear reactor plant, the operation-independent part is stored in advance in a database on the computer network, and the data linkage management means Is received from the boiling water reactor plant, and the operation-dependent part and the operation-independent part are compiled and restored as complete data, and the data linkage management means periodically performs the operation-independent part. By confirming the synchronization of data contents and updating only the latest data for operation-dependent parts Comprise means for confirming the consistency of data between different networks, characterized by.

Further, the transient fuel integrity evaluation method according to the present invention includes a plant dynamics simulation step for evaluating the transient behavior of a boiling water reactor plant by simulating nuclear thermal hydraulic characteristics of the core of a boiling water reactor. And a core management step for monitoring and managing the state of the core, a process management step for monitoring and managing the process volume based on the measurement data of the boiling water reactor plant, and a transient measurement of the boiling water reactor plant. Transient phenomena management step that records and manages data, and the system that executes the plant dynamic characteristic simulation step, core management step, process management step, and transient phenomenon management step are linked via a network, and data transfer necessary for the linkage is performed. And data linkage management steps for processing, plant measurement data and simulator input data And database management step of managing the simulation results and the and user interface steps for performing data input and output to the user, a transient fuel soundness evaluation method having the data handled by the data linkage management step The operation-dependent portion depending on the operation state of the boiling water reactor plant and the operation-independent portion independent of the operation state of the boiling water reactor plant are separated, and the operation-independent portion is the computer network. The data linkage management step stores the operation-dependent part from the boiling water reactor plant and then compiles the operation-dependent part and the operation-independent part to complete data. And the data linkage management step includes the operation independence. Periodically performs synchronization confirmation data content for the portion, and for operating dependent part, by updating only the most recent data, further comprising the step of confirming the consistency of data between different networks, characterized by.

  According to the present invention, when an abnormal transient change during operation occurs in a boiling water reactor or when some kind of fuel integrity evaluation is required, a nuclear thermal hydraulic characteristic analysis of the core is quickly performed. be able to.

  Hereinafter, embodiments of a transient fuel integrity evaluation system for a boiling water reactor according to the present invention will be described with reference to the drawings.

[First Embodiment]
First, the first embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a conceptual diagram showing the overall configuration of the present embodiment. There is a communication network 10 connected directly or between the plant control transmission network 2 of the boiling water reactor 1 via a firewall or the like. On this communication network 10, a transient phenomenon management system 20 that records and manages plant process data that is transient measurement data, a core management system 21 that monitors and manages the core state, and a process based on the measurement data of the power plant. There is a process management system 22 that monitors and manages the quantity, but these systems are usually existing functions installed on the transmission network of the power plant.

  On the other hand, the plant dynamic characteristic simulator 30, the data linkage management function 31, the database management function 32, and the user interface function 33 are newly added in the present embodiment, and are not necessarily present on the transmission network of the existing power plant. Do not mean.

  FIG. 2 shows a data flow in the transient fuel integrity evaluation system for a boiling water reactor according to the present invention. The center is a plant dynamic characteristic simulator 30, which has a function of simulating the nuclear thermal hydraulic dynamic characteristic of the core in detail and simulating the dynamic characteristic behavior of the entire plant. That is, with respect to the core 35, as shown in FIG. 3, the boiling water reactor has a large number of fuel assemblies 36 surrounded by a rectangular channel box 37 (872 in the improved boiling water reactor). The core 35 is configured by being loaded.

  Each fuel assembly 36 is constituted by a number of fuel rods 38 (74 of 9 × 9 fuel) and water rods 39 arranged in a square lattice pattern. The plant dynamic characteristic simulator needs to have a function capable of evaluating the soundness of the individual fuel rods 38 included in the entire core 35. Therefore, the plant dynamic characteristic simulator requires input data necessary for this evaluation. It is a first object of the present invention to assist in quickly and reliably preparing these input data.

  Returning to the data linkage diagram of FIG. 2, the input data template of the plant dynamic characteristic simulator 30 is stored and managed in the analysis support database 42. When the plant dynamic characteristic simulator 30 is activated and analyzed, input data closest to the plant condition to be analyzed is selected as a template. The activation, that is, the start of the analysis is set in the database management function 32 that manages the plant measurement data, the simulator input data, and the simulation result in advance when the user activates after setting the conditions through the user interface function 33, for example. When automatically starting based on the set cycle, or when some abnormal event occurs in the operation state of the plant, it automatically starts based on the procedure set in the database linkage management function 31 in advance. Multiple startup timings are possible.

  Data required to make the input conditions of the template selected from the analysis support database 42 as close as possible to the operating state of the plant to be analyzed include core data 40 and process data 41. The core data 40 is mainly related to the neutron flux distribution and core power distribution of the core 35 and is necessary for the three-dimensional neutron dynamic characteristic model possessed by the plant dynamic characteristic simulator 30, which is obtained from the core management system 21. To do. The process data 41 includes data relating to the process amount of the plant such as heat balance, and time series data of various process data that are transient characteristics of the plant, and is necessary for balance of the entire plant including the core and evaluation of the transient characteristics. These are data and are obtained from the process management system 22 and the transient phenomenon management system 20.

  Not all of these data are necessary for dynamic characteristics analysis, and the data format and its meaning may differ from system to system, so only the necessary data is selected and extracted, and finally the plant The data linkage management function 31 provides a function of converting into the input data format of the dynamic characteristic simulator 30. The above is the flow of input data.

  There is another output data flow. In FIG. 2, the analysis result 43 of the plant dynamic characteristic simulator 30 includes a lot of information, and the information required by the user (user) is selected from among the information, and the user interface function 33 is displayed in various formats. And provide data via Such an information management function is included in the analysis support database 42 and its management function. In addition, the analysis result information is not only displayed to the user, but also used as a template for new input data from the viewpoint of correlation with the analysis conditions, or used for reliability evaluation of analysis results described later. can do. In this sense, the output information has not only a simple output but also a bidirectional flow that can be input information.

  That is, in the present embodiment, a function for quickly and accurately analyzing the soundness of the fuel loaded in the core of the boiling water reactor is provided, and at the same time, input information including plant information for output information of the analysis. By evaluating the correlation, it is possible to provide a function that increases the reliability of the function, and it is possible to contribute to improving the safety and reliability of the boiling water reactor.

[Second Embodiment]
Next, a second embodiment in the case where there is a restriction on cooperation between networks when performing data cooperation according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and the overlapping description is abbreviate | omitted.

  As described in the first embodiment, the systems for providing the functions of the present invention are not necessarily on the same communication network. If they are on the same network, all the functions of the present invention are realized in the central control room of the boiling water reactor and all exist on the control transmission network of the power reactor. FIG. 4 shows a first cooperation format assumed in the present embodiment.

  That is, the plant control transmission network 2 and the communication network 10 are linked through the gateway function 50. In this case, a firewall is often set for the gateway function 50 to restrict access between the networks. If there is such an access restriction, the inter-system cooperation as shown in FIG. 1 cannot be performed as it is, so some cooperation means is necessary. There is a possibility of linking via a special port dedicated to this system, but that port may become a security hole or violate security policies between organizations. There are many problems.

  As a means capable of cooperation between gateways without providing such a special security hole, there is a web cooperation using electronic mail and a secure protocol (HTTP (Hypertext Transfer Protocol Security)). HTTPS is a Web service that combines HTTP (HyperText Transfer Protocol), which is a Web service protocol on a normal network, with encryption using SSL (Secure Socket Layer), which is a higher-level encryption protocol. It is a data linkage means that enhances data security. In the Web service, it is easy to use automatic processing means for cooperation in a language such as Java (trademark).

  The present invention is characterized by avoiding communication restrictions between networks by appropriately combining these means. The data linkage management function provides such a function and performs linkage management, and is installed in each linked network as shown in FIG. 4 to realize load distribution and improved reliability.

  Furthermore, the network to be linked may not be directly connected due to security. As shown in FIG. 5, in this case, there is no choice but to cooperate once by writing to some electronic recording medium 51 and reading from the electronic recording medium. As the electronic recording medium, a large capacity and complete security function such as a USB (universal serial bus) memory, a CD (compact disc), a DVD (digital versatile disc) can be used. The data linkage management function 31 also provides execution management of writing and reading in this case.

  For example, when a data transfer processing command is automatically issued from the network 2 by the user or from the data linkage management function 31, the data linkage management function 31 writes the data body into the electronic recording medium 51 according to the content. When the writing is completed, the data linkage management function 31 notifies the user via the user interface 33 to that effect. The user takes out the electronic recording medium 51, sets it as a device connectable to the communication network 10, and reads it. In this case, not only the data body but also the data body is read into the electronic recording medium, converted into a data format that can be used at the cooperation destination, and passed to the data cooperation management function 31 on the communication network 10. In this way, by adding a processing function to the data body, it is possible to avoid a human error caused by the user.

  In the case of data transfer, security is improved by sending the data processing function and the data to be processed by separate e-mails or accessing from another URL (uniform resource locator). In other words, the data itself is in a meaningless format, and it is converted into meaningful data only after processing sent by a separate flight. It is a method of sending the main body separately.

  This situation is shown in FIG. That is, the entire linkage data 60 constitutes a kind of object format comprising a processing part for accessing data, that is, a method 61 and a data body part 62 that is converted into a format usable for the first time through the method 61. is doing. Here, by transferring the method 61 portion and the data body portion 62 separately, usable data (restored data body) 63 can be obtained only after the both are prepared. Here, if a method is prepared as one of the data linkage management functions 31 of each network, information (method ID) that clearly indicates the function is sent instead of the method 61, and the data is not obtained until both have been prepared. There is also a method of starting the method 61 of the cooperation management function 31 and restoring the data.

  That is, in the embodiment of the present invention, regardless of the configuration of the target network, it is possible to link data with security without changing the security policy, etc., and the safety and reliability of the boiling water reactor It is thought that it contributes to improvement.

[Third Embodiment]
Next, a third embodiment of the present invention for data division at the time of data transfer and ensuring consistency between databases will be described with reference to FIG. The input data of the plant dynamic characteristic simulator can be roughly divided into operating state dependent data 64 that depends on the operating state of the boiling water reactor plant and operating state independent data 65 that does not depend on the operating state of the boiling water reactor plant. . For example, regarding the core management data, data relating to the core shape, cell nuclear constants, and the like belong to the operating state independent data 65 that does not depend on the operating state. On the other hand, the heat balance data, the control rod insertion state, the relative water density distribution, and the like belong to the operation state dependent data 64 depending on the operation state. In addition, although there is no change in a short time span, there is a burnup or the operation history dependent data 66.

  Therefore, as for the operation state-independent data 65, if the same data as the power plant side is made resident in the database on the computer network on the site side where the plant dynamics simulation is performed, it is not necessary to transfer the portion one by one. . Further, with respect to the operation history dependent data 66, only the latest portion 67 is transferred at the time of updating, and updated to the latest history dependent data in the database on the site side network where the plant dynamic characteristic simulation is performed. . Therefore, only the operation dependent part is transferred when the analysis is activated.

  Further, it is confirmed that the data periodically matches between the operation state independent data 68 on the network on the site side where the plant dynamic characteristic simulation is performed and the operation state independent data 65 on the power plant side. This ensures data consistency.

  By compiling the data divided according to the dependence on the operating state in this way, it is possible to restore and complete the data set necessary for executing the plant dynamic characteristic simulation.

  According to the form of this embodiment, when plant dynamic characteristic simulation becomes necessary, it is possible to minimize the data that needs to be prepared, and execute quick and reliable plant dynamic characteristic simulation. This can contribute to the improvement of safety and reliability of the boiling water reactor.

[Fourth Embodiment]
Next, a fourth embodiment relating to ensuring consistency between data in data collection according to the present invention will be described with reference to FIGS. For example, as shown in the third embodiment, when there are three types of data as driving state dependent, independent, and history, the driving state independent data has the smallest update interval, and the driving state dependent data is For example, the update interval is fine, such as updating every hour. It is necessary to check consistency when compiling data between data updated at such different intervals. Information necessary for this is data consistency confirmation information 69. The top information of the information is data update time.

  When analysis is required and the condition 70 is instructed, at least the data to be used needs to be the newest information that is most updated before the time set for the condition. Next, the update time is updated in ascending order of the update interval between the data. After that, it includes the same plant, information that is unique for each target transient event, information that enables definition and unit correspondence between individual parameters, and the like.

  For example, when individual flow rates are given to the recirculation pumps in the process data and the core flow rate that is the sum of them is required in the analysis, there is a function that converts the sum of the individual flow rates into the core flow rate. Although necessary, it is also necessary to include information necessary for such conversion processing.

  Such confirmation of consistency is also necessary among core data, process data, analysis support data, and the like as shown in the first embodiment. Such data consistency check processing 71 is handled by the data linkage management function.

  The time stamp of the update time is usually measured with the clock of the computer on which the individual system is loaded, and there is no problem if the clocks are all adjusted to point to the same time. There is a case where such operation is not performed. In this case, first, there are time servers 23 and 24 for providing a reference time to each network, and each computer periodically adjusts the time of the time servers 23 and 24, or data consistency Time difference information with the time server is added to the update time of the confirmation information so that time correction or synchronization confirmation can be performed.

  Further, a means for confirming that the time servers 23 and 24 existing in a plurality of networks provide the same time is also necessary. This situation will be described with reference to FIG. There is a time server 23 in the network 2 and a time server 24 in another network 10, and a clock such as a database monitoring system existing in each network is adjusted by this server or The correction information (time difference) is added to the data update information of each data. The two time servers 23 and 24 need to have information for guaranteeing that they are adjusted with respect to a certain reference clock 25, and such information is also included in the data consistency confirmation information.

  In this embodiment configured as described above, it becomes possible to quickly prepare complete data necessary for collecting a plurality of data and executing a plant dynamic characteristic simulator therefrom as being consistent, This is thought to contribute to improving the safety and reliability of boiling water reactors.

[Fifth Embodiment]
Next, a fifth embodiment for optimizing the creation of input data for a plant dynamic characteristic simulator according to the present invention will be described with reference to FIG. As described in the first embodiment, the analysis support database 42 stores verified input data used in past analysis results and the like. By using such verified input data as a template for new input data for analysis, the input data can be created with minimal correction, and the requested analysis can be performed more quickly and with high accuracy.

  In this case, search information for selecting optimal template data is important. It is necessary to match the template data 73 serving as the base of the input data with the condition of the event to be analyzed, and for this purpose, an index used for matching is required. As shown in FIG. 10, first, a similarity index 72 used for matching is automatically generated from an analysis condition instruction. On the other hand, the similarity index 74 is already added to the individual template data 73 stored in the analysis support database 42 as data header information. Matching may be performed between these two indicators. What is set as an index depends on the matching procedure, but one of them is a procedure for minimizing the effort (change location and time) required for data reconstruction.

  Since the effort is minimized, the same data simulation system is the top priority. In other words, when the target simulation system is different, it is necessary to add or delete new system configuration data (component data). However, since it is related to the system, it is necessary to reconfirm the consistency of the entire system. , It takes a lot of work. On the other hand, the difference in operating conditions is, for example, much easier compared to the labor involved in changing the system if only changing the core conditions and rebalancing the plant balance. The similarity is higher in the selection priority.

The effort for data reconstruction due to the difference in similarity is made into a function or table for each similarity, and the overall effort is calculated from the similarity between the analysis conditions and each template so that it is minimized. The right template. That is,
Effort = function (similarity 1, similarity 2, ..., similarity N)
If such a relationship is set, this is performed for each template, and the template obtained with the minimum effort (the shortest time) is formally adopted. This is an example of the processing flow written on the right side of FIG. This similarity is defined here as an absolute value of the difference, or as an index representing the difference in similarity, such as 0 if they are the same or 1 if they are different. If it is consistent, as the name indicates, it is possible to define the similarity index as 1 if it is the same, 1 if it is the same, and 0 if it is different.

As one specific example of the function, if a weighting factor is set in advance for each similarity,
Effort = weight 1 * similarity 1 + weight 2 * similarity 2+... + Weight N * similarity N
A simple relationship is obtained. If the previous example is used, the similarity weight related to the system is large, and the similarity weight related to the driving condition is small. Also, the weights differ for each parameter regarding the system and operating conditions.

  For example, the difference in operating conditions that can be adjusted simply by resetting the control system, etc., depends on the type of control system, but the weight is small. Become bigger. Further, if the evaluation item with the highest priority is accuracy, each weighting factor is also different, so it is necessary to prepare another weighting factor or function form. Furthermore, when there are a plurality of evaluation items such as labor and accuracy, the relative importance between the evaluation items is set as a weight, or is set when the user gives an analysis condition instruction. Thus, the composite evaluation index is finally reduced to one evaluation index for evaluation.

  In this case, it is necessary to adjust the evaluation formula and the sign of the weighting coefficient so that the direction of the index is the same. For example, in the case of labor and accuracy, it is necessary to decrease the labor and improve the accuracy in the same direction of increase / decrease. The general form of the evaluation formula is as follows.

Evaluation function = weight 1 * evaluation item 1 (weight, similarity)
+ Weight 2 * evaluation item 2 (weight, similarity)
+ ··· + Weight M * Evaluation item M (weight, similarity)
In this embodiment configured as described above, it is possible to collect a plurality of data and prepare the optimum complete data necessary for executing the plant dynamic characteristic simulator from them as quickly consistent. Thus, the safety and reliability of the boiling water reactor can be improved.

[Sixth Embodiment]
Next, the reflection of the analysis result based on the uncertainty evaluation of the parameter according to the present invention in the reliability evaluation and the sixth embodiment relating to the input data creation support will be described with reference to FIGS. The fuel integrity index evaluated by this system is primarily the minimum critical power ratio (MCPR). This is an index indicating that the fuel soundness can be secured without occurrence of boiling transition (BT) with a sufficiently reliable probability if it is greater than a certain value (safety limit minimum limit output ratio) at the time of transition. This is a correlation equation obtained by performing a number of BT tests on a specific fuel shape, and the typical safety limit minimum limit power ratio value is 1.07, indicating a sufficiently reliable probability. Is 99.9%.

  The fuel integrity of boiling water reactors represented by MCPR includes operating conditions such as power and flow rate, plant data such as spacer pressure loss and separator pressure loss, core conditions such as void coefficient and Doppler coefficient, and nuclide. It depends on various parameter values such as simulator model conditions such as correlation equations.

  Those parameters have inherent uncertainties. For example, measurement values such as output and flow rate cannot naturally avoid measurement errors, and the correlation equation used by the simulator model cannot be avoided by applying the reliability associated with certain uncertainties in its accuracy. . In addition, in the event that a control rod such as a scram is inserted, the fuel soundness greatly depends on the insertion speed, but each control rod drive mechanism has a variation in manufacturing and the insertion speed depending on the operating state. There is always variation.

  For example, in FIG. 11, each of the n parameters that affect the fuel health index, MCPR of a transient event is typically a normal distribution (which may be a uniform distribution), and the values are distributed. Then, the MCPR value evaluated based on these uncertainties follows the normal distribution 80. Here, the spread of the normal distribution is the reliability of the fuel soundness evaluation, and the narrower this is, the higher the reliability is.

  Therefore, for example, assuming that the measurement accuracy of a certain parameter is improved, and the distribution of the evaluated MCPR becomes a normal distribution 81 as shown in FIG. 11, the reliability is improved. Typically, the reliability is improved by the width D shown in FIG. If the degree of reliability improvement evaluated in this way is used as a matching evaluation index for the accuracy described in the fifth embodiment, it can be used for selecting an optimum input data template from the viewpoint of accuracy. This detailed embodiment is described below.

  Uncertainty of each parameter affecting the fuel soundness of a transient event in FIG. 11 can be evaluated from experience such as measurement value accuracy and analysis accuracy so far. Since there is sensitivity to the effect on the fuel integrity, it is necessary to narrow down parameters with high sensitivity. Specifically, fuel soundness evaluation is performed for each parameter using a plant dynamic characteristic simulator using the upper and lower limit values for the uncertainty, and the sensitivity of the parameter of the evaluation result is obtained.

  Here, only a single sensitivity of each parameter can be evaluated, but those having a small single sensitivity can be considered as having a small interaction with other parameters. If the number of parameters can be reduced to about several by such narrowing down, sensitivity analysis including the alternating effect between parameters can be performed. As a result, it is possible to obtain a sensitivity curve with respect to fuel soundness from parameters that greatly affect fuel soundness in a certain transient analysis. The range covered by such a sensitivity curve is usually wider than the range covered by a single parameter, and the reliability will be reduced accordingly. On the other hand, the reliability can be shown simultaneously.

  That is, if the distribution 84 is the sensitivity to the fuel health index due to the uncertainty of the parameter as the distribution of the fuel health index when the uncertainty in a transient event with a distribution 83 in FIG. 12 is not considered, A distribution 85 obtained by combining both is a distribution of the fuel soundness index of the event in consideration of the parameter uncertainty. If the vertical line 87 is defined as a safety limit, the region 88 is a fuel region where there is a problem with fuel soundness when uncertainty is not considered, and the region 89 is a region where there is a problem with fuel soundness when uncertainty is considered. Yes, taking into account parameter uncertainties, we have to consider fuel rods in this region.

  FIG. 12 is a schematic diagram. In actuality, the safety limit minimum limit output ratio is shifted to a larger value by the uncertainty width in consideration of parameter uncertainty. This means that the fuel assembly showing a value equal to or less than the safety limit minimum limit output ratio corrected in this way has a problem in terms of fuel soundness, and it is necessary to take subsequent measures such as specifying a detailed BT occurrence location.

Next, if the parameters are narrowed down by the sensitivity analysis of the related parameters with respect to the fuel integrity evaluation index of a specific transient event, and the sensitivity curved surface for the narrowed parameters is obtained, the similarity matching described in the fifth embodiment is performed. It can be applied to the optimal input data selection by. In other words, since the fuel integrity evaluation index is an index related to accuracy,
Accuracy = function (weight, similarity)
As the similarity, select as the absolute value of the difference of each parameter, and if the similarity parameter considered here is the parameter considered in the sensitivity surface, if the sensitivity surface is selected as a function, it will be used as a similarity evaluation index for accuracy as it is The method of the fifth embodiment can be used.

  In this embodiment configured as described above, by evaluating the sensitivity of the target transient event regarding the uncertainty of the core and plant parameters in advance, the effect of the uncertainty on the analysis result of the plant dynamics simulator Can be taken into account, which makes it possible to avoid non-conservative evaluation and excessively conservative evaluation, and to efficiently associate the optimal input data template with accuracy. It will be possible to select it, which will contribute to the improvement of safety and reliability of boiling water reactors.

[Seventh Embodiment]
Next, an example of a method for performing a simple fuel integrity evaluation using the sensitivity curved surface related to the core / plant parameters according to the present invention will be described with reference to FIG. The sensitivity curve 90 is generally
Fuel integrity evaluation index = function (parameter 1, parameter 2, ...)
Is given in the form of a function or function table. Here, each parameter may be a scalar value, or may be a distribution (probability distribution). In the latter case, the fuel health evaluation index also corresponds in the form of distribution. Therefore, when a certain transient event analysis is required, it can be used for a simple evaluation before a detailed analysis by a plant dynamic characteristic simulator. That is, if a parameter value 91 having a high sensitivity in the plant state to be analyzed is input to the sensitivity curved surface 90 obtained in advance for the target transient event, the fuel integrity evaluation index 92 (in this example, the probability) Distribution) will be obtained immediately. From this simple evaluation, analysis conditions can be selected and urgent measures can be taken.

  In this embodiment configured as described above, the sensitivity regarding the uncertainty of the core and plant parameters of the target transient event is evaluated in advance as a sensitivity curved surface, so that the detailed analysis result by the plant dynamics simulator can be obtained. Since a simple fuel integrity assessment can be performed quickly before being obtained, it is thought to contribute to improving the safety and reliability of boiling water reactors.

[Eighth Embodiment]
Next, when a sensitivity curved surface relating to the core and plant parameters according to the present invention is obtained, a method for verifying an analysis result using a detailed plant dynamic characteristic simulator using the sensitivity curved surface will be described with reference to FIGS. Describe.

  It is assumed that the sensitivity curved surface 90 is obtained for a specific transient phenomenon in the format described in the seventh embodiment. On the other hand, analysis conditions are instructed to the plant dynamic characteristic simulator, a complete input data set 93 is prepared, and an analysis is performed based on the input data set 93. As a result of analysis, a probability density distribution 94 of the fuel health index is obtained. To do. Here, a probability density distribution 92 of a fuel soundness index by simple evaluation corresponding to the distribution 94 is obtained by giving the corresponding sensitivity parameter input 91 to the sensitivity curved surface 90 from the input data 93 of the simulator. Can be used for verification evaluation of the distribution 94 which is the analysis result of the simulator.

  The evaluation items include the degree of deviation from the normal distribution (such as kurtosis and harshness), the deviation from the verification distribution such as the average and variance of the normal distribution, and comparison with a preset standard value for deviation. Do. If the deviation is greater than or equal to the reference value based on these comparison results, it is highly possible that the analysis result of the plant dynamic characteristic simulator is insufficient, and it is necessary to review the input data and analysis conditions.

  The outline of the data review procedure is as follows. If a distribution deviating from the normal distribution such as an abnormal value is obtained, it is often the case that a condition that does not match the original transient analysis, such as the analysis condition or analysis system, is used. After finding out, check the conditions that affect the behavior of the parameter.

Regarding the deviation of the probability distribution of the fuel integrity evaluation index from the standard distribution for verification, the procedure as shown in FIG. 15 can be used. That is, in addition to the sensitivity curved surface from a plurality of parameters described in the seventh embodiment, a sensitivity curved surface from a single parameter is also evaluated and prepared for each transient event. That is, for each single parameter, fuel integrity evaluation index 1 = function (parameter 1)
Fuel soundness evaluation index 2 = function (parameter 2)
...
Fuel integrity evaluation index n = function (parameter n)
Are prepared for verification, and the average value and variance of the probability distribution of the fuel health evaluation index for each parameter have also been evaluated. Each value deviation can be evaluated.

  If the deviation is specific to a parameter, it can be found that the parameter is the cause, but if the influence from multiple parameters is considered, mathematical programming that minimizes the mean deviation and variance deviation For example, using nonlinear programming, the contribution to the deviation from each parameter is evaluated, and the input data is checked from the parameter having the large contribution. Alternatively, the combination of parameter values on the standard sensitivity surface that minimizes the deviation between the verification sensitivity surface and the standard sensitivity surface is evaluated by applying the minimum gradient method or nonlinear programming to the sensitivity surface 90 itself. You can also By comparing the parameter value obtained as a result with the value instructed by the analysis condition, it is possible to confirm the error of the input data or the analysis condition.

  By sequentially adding such a reliability evaluation result to the reliability evaluation database, it can be used as a cause investigation support when a similar reliability evaluation result is obtained. FIG. 16 shows the circumstances. Since the sensitivity curved surface is determined within a predetermined parameter uncertainty range, an analysis result such as a condition setting error or an input data error may appear at a location 95 far away from the sensitivity curved surface. Therefore, by associating such a setting error case 96 with the information of the divergence area, the average value of the probability density function, and the deviation of the variance value, the same area on the sensitivity surface, Or when the similar probability density deviation is obtained, the past applicable case can be referred to promptly.

  Alternatively, a sensitivity surface in a region that deviates from the parameter uncertainty range is purposely obtained in advance and stored in the reliability evaluation database to quickly respond to such unexpected mistakes. It becomes possible to do.

  In this embodiment configured as described above, the sensitivity relating to the uncertainty of the core and plant parameters of the target transient event is evaluated in advance as a sensitivity curved surface, and is used as a standard sensitivity curved surface for verification. It can be used to evaluate the reliability of detailed analysis results by the plant dynamics simulator, and can be used to investigate the causes of deviations from standard values such as incorrect condition settings and input data errors. It is thought to contribute to improving safety and reliability.

1 is a block diagram showing a configuration of a first embodiment of a transient fuel soundness evaluation system according to the present invention. It is a block diagram which shows the structure for the data cooperation in 1st Embodiment of the fuel health evaluation system at the time of the transition which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the example of the fuel assembly used as the evaluation object in 1st Embodiment of the fuel integrity evaluation system at the time of the transition which concerns on this invention, Comprising: (a) is a typical cross-sectional view of the whole core, (b) Is a perspective view of one fuel assembly, and (c) is a schematic enlarged cross-sectional view of one fuel assembly. It is a block diagram which shows the structure of 2nd Embodiment of the fuel health evaluation system at the time of the transition which concerns on this invention. It is a block diagram which shows the structure of the modification of 2nd Embodiment of the fuel health evaluation system at the time of the transition which concerns on this invention. It is a block diagram which shows the example of the data division | segmentation in 2nd Embodiment of the fuel health evaluation system at the time of the transition which concerns on this invention. It is a block diagram explaining the example of the transfer data division | segmentation in 3rd Embodiment of the fuel health evaluation system at the time of the transition which concerns on this invention. It is a block diagram which shows the structural example for the data consistency ensuring in 4th Embodiment of the fuel integrity evaluation system at the time of the transition which concerns on this invention. It is a block diagram which shows the structural example for the time setting in 4th Embodiment of the fuel health evaluation system at the time of the transition which concerns on this invention. It is a flowchart which shows the input data creation procedure for the plant dynamics simulator in 5th Embodiment of the fuel integrity evaluation system at the time of the transition which concerns on this invention. It is explanatory drawing which shows the procedure which evaluates the intrinsic uncertainty which each parameter has in 6th Embodiment of the fuel integrity evaluation system at the time of the transition which concerns on this invention. It is explanatory drawing which shows the fuel integrity evaluation method which considered the uncertainty of the parameter in 6th Embodiment of the fuel integrity evaluation system at the time of the transition which concerns on this invention. It is explanatory drawing which shows the soundness evaluation method in 7th Embodiment of the fuel soundness evaluation system at the time of the transition which concerns on this invention. It is explanatory drawing which shows the soundness evaluation method in 8th Embodiment of the transient fuel soundness evaluation system which concerns on this invention. It is explanatory drawing which shows the procedure which examines the shift | offset | difference from the verification standard distribution of the probability distribution of a fuel soundness evaluation index | exponent in 8th Embodiment of the fuel health evaluation system at the time of the transition which concerns on this invention. It is explanatory drawing which shows the soundness evaluation method in consideration of the condition setting mistake, the input data error, etc. in 8th Embodiment of the fuel health evaluation system at the time of the transition which concerns on this invention. It is a graph which shows the reference | standard of post BT by making a vertical axis | shaft into fuel cladding tube temperature and making a horizontal axis into dryout duration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Boiling water reactor 2 ... Plant control transmission network 10 ... Communication network 20 ... Transient phenomenon management system 21 ... Core management system 22 ... Process management system 30 ... Plant dynamic characteristic simulator 31 ... Data cooperation management function 32 ... Database management function 33 ... User interface function 40 ... Core data 41 ... Process data 42 ... Analysis support database 43 ... Analysis results

Claims (8)

A plant dynamics simulator capable of evaluating the transient behavior of a boiling water reactor plant by simulating the nuclear thermal hydraulic characteristics of the core of a boiling water reactor;
A core management system for monitoring and managing the state of the core;
A process management system that monitors and manages the process volume based on the measurement data of the boiling water reactor plant;
A transient phenomenon management system that records and manages transient measurement data of a boiling water reactor plant;
Data linkage management means that links these systems through a network and performs data transfer and processing necessary for linkage,
Database management means for managing plant measurement data, simulator input data and simulation results;
User interface means for performing data input / output to the user,
A transient fuel integrity assessment system comprising:
The data handled by the data linkage management means is separated into an operation-dependent part that depends on the operation state of the boiling water reactor plant and an operation-independent part that does not depend on the operation state of the boiling water reactor plant. ,
The operation-independent part is stored in advance in a database on the computer network,
The data linkage management means, after receiving the operation-dependent portion from the boiling water reactor plant, compiles the operation-dependent portion and the operation-independent portion to restore as complete data,
The data linkage management means periodically checks the data contents for the operation-independent part, and confirms data consistency between different networks by updating only the latest data for the operation-dependent part. Including means to
Transient fuel integrity evaluation system.   2. The transient fuel soundness evaluation system according to claim 1, wherein the data linkage management means includes means for performing communication restriction and means for avoiding the communication restriction.   The data linkage management means uses any one of e-mail, a web service via a secure protocol, a recording medium having an automatic save / restore function, or a combination thereof. The transient fuel integrity evaluation system according to claim 2.   The data linkage management means converts the data into an object format that requires processing for restoration unless the data body is restored, and transfers the data and the data body between different networks. 4. The transient fuel health evaluation system according to claim 3, wherein security of data transfer is improved by separately transmitting and. A plurality of databases are arranged on the network,
Data required to create input data that is consistent with the target analysis conditions when collecting a plurality of data from the plurality of databases and generating input data necessary for execution of the plant dynamics simulator Each data has the verification process of consistency between them and the verification information necessary for the verification process,
The transient fuel integrity evaluation system according to any one of claims 1 to 4, wherein: When checking the consistency between the data, the data update time has means for correcting the difference in time due to the difference in time servers, and each data has information necessary for the correction. The fuel integrity evaluation system at the time of transition according to claim 5. When collecting a plurality of data from the plurality of databases and generating input data necessary for execution of the plant dynamic characteristic simulator, data for an analysis event corresponding to the shortest time from a reference input data template 6. The transient fuel soundness evaluation system according to claim 5 , wherein each template information includes means for retrieving the information, and information necessary for the retrieval is provided . A plant dynamics simulation step to evaluate the transient behavior of the boiling water reactor plant by simulating the nuclear thermal hydraulic characteristics of the boiling water reactor core;
  A core management step for monitoring and managing the state of the core;
  A process management step for monitoring and managing the process volume based on the measurement data of the boiling water reactor plant;
  Transient phenomena management step to record and manage transient measurement data of boiling water reactor plant,
  A data linkage management step for performing data transfer and processing necessary for linkage by linking the systems that execute the plant dynamic characteristic simulation step, core management step, process management step, and transient phenomenon management step through a network,
  Database management steps for managing plant measurement data, simulator input data and simulation results;
  A user interface step for performing data input / output to a user;
  A transient fuel integrity assessment method comprising:
  The data handled in the data linkage management step is separated into an operation-dependent part that depends on the operating state of the boiling water reactor plant and an operation-independent part that does not depend on the operating state of the boiling water reactor plant. ,
  The operation-independent part is stored in advance in a database on the computer network,
  In the data linkage management step, after receiving the operation-dependent part from the boiling water reactor plant, the operation-dependent part and the operation-independent part are compiled and restored as complete data,
  The data linkage management step periodically checks the data contents for the operation-independent portion, and checks only the latest data for the operation-dependent portion, thereby confirming data consistency between different networks. Including the step of
  A fuel integrity evaluation method at the time of transition characterized by

Images