JP7273683B2 - Defect Tolerance Evaluation Apparatus and Defect Tolerance Evaluation Method - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to a defect tolerance evaluation apparatus and a defect tolerance evaluation method.

As the aging of nuclear power generation facilities and the extension of their lifespan progress, the risk of occurrence of aging degradation events is increasing, and it is becoming more important to deal with it. Stable operation and improvement of availability of power generation facilities are important from the viewpoint of efficient utilization of power generation facilities as a whole and stable supply of electric power.

Conventionally, in the soundness evaluation when defect indications due to aging deterioration are detected by inspection of equipment, structures, etc., the dimension measurement (sizing) of the defect is performed, and the defect evaluation is performed based on the result. Then, based on the result of the defect evaluation, a decision is made as to whether to continue operation, repair, replace, or the like. In this process, the entire power generation facility continues to be stopped during the period required from defect evaluation to judgment. Furthermore, when construction such as additional inspections, repairs, and replacements is required, it takes time for the physical preparations required for the construction work and for approvals and approvals, and the suspension period may extend even longer.

Japanese Patent Application Laid-Open No. 2002-062901

Conventionally, starting with preparation of necessary input parameters including sizing results of detected defects, stress analysis, implementation of evaluation, analysis of evaluation results, repair and maintenance of target equipment and structures. A decision is made as to whether to take measures such as replacement, and whether or not to continue the operation. Until this conclusion was drawn, the outage period of the entire facility continued, sometimes for a long time.

The embodiments of the present invention have been made in view of such problems, and provide a defect tolerance evaluation apparatus and a defect tolerance evaluation method that can quickly determine how to respond when a defect is detected. for the purpose.

In order to achieve the above object, the defect tolerance evaluation apparatus according to the present embodiment includes a defect size setting unit that sequentially sets the size of an initial defect assumed in an evaluation target portion, and a defect progress amount based on the size of the initial defect. a determination unit for determining whether a predetermined allowable defect size has been reached, and the size of the initial defect set in sequence and the allowable defect size which is the time to reach the predetermined allowable defect size. A defect tolerance map creation unit that creates a defect tolerance map showing the relationship with the arrival time, an initial operation plan storage unit that stores the initial operation plan, and an assumed case that is assumed as a response when a defect is detected. Using the assumed case database and the defect tolerance map based on the dimensions of the initial defect, the time to reach the allowable defect size is derived, and the plant operation period ends according to the initial operation plan stored in the initial operation plan storage unit. A remaining time derivation unit for deriving a planned remaining time up to a point in time; a case extracting unit for extracting an assumed case from the assumed case database based on the allowable defect size reaching time and the planned remaining time; an element cost database that stores cost data about elements; and a case evaluation unit that calculates an evaluation function value using the cost data stored in the element cost database for each of the hypothetical cases extracted by the case extraction unit. and a selected case determination unit that determines a selected case from among the assumed cases extracted by the case extraction unit based on the evaluation function value.

Further, the defect tolerance evaluation method according to the present embodiment includes an initial defect size setting step of sequentially setting the size of an initial defect assumed in an evaluation target portion, and a defect progress amount of calculating a defect progress amount based on the size of the initial defect. a determination step of determining whether a predetermined defect size has been reached and, if not, repeating the step of calculating the defect progress amount; a defect tolerance map creating step of creating a defect tolerance map that organizes the relationship between the allowable defect dimension arrival time that is the arrival time of the defect tolerance map, and the allowable defect dimension arrival time using the defect tolerance map based on the dimensions of the initial defect and a remaining time derivation step of deriving the planned remaining time until the end of the plant operation period according to the initial operation plan stored in the initial operation plan storage unit, and based on the allowable defect dimension reaching time and the planned remaining time a case extraction step of extracting hypothetical cases from the hypothetical case database, and a case evaluation step of calculating an evaluation function value for each of the hypothetical cases extracted by the case extraction step using the costars stored in the element cost database; and a selected case determination step of determining a selected case from the assumed cases extracted in the case extraction step based on the evaluation function value.

According to the embodiments of the present invention, it is possible to provide a defect tolerance evaluation apparatus and a defect tolerance evaluation method that can quickly determine what to do when a defect is detected.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the structure of the defect tolerance evaluation apparatus which concerns on embodiment, and the structure of the defect tolerance map preparation apparatus of them. It is a conceptual cross-sectional view explaining an initial defect of an evaluation target portion of the defect tolerance evaluation apparatus according to the embodiment. 3 is a conceptual cross-sectional view taken along the line III-III of FIG. 2 for explaining an initial defect of an evaluation target portion of the defect tolerance evaluation apparatus according to the embodiment; FIG. FIG. 2 is a flow chart showing the overall procedure of the defect tolerance evaluation method according to the embodiment; FIG. 4 is a flow diagram showing a specific procedure of a defect tolerance map creating step in the defect tolerance evaluation method according to the embodiment; 10 is a graph showing defect progress analysis results showing the relationship between time and initial defect size with the aspect ratio of the initial defect as a parameter by the defect tolerance evaluation apparatus according to the embodiment, showing the case where the initial defect depth is 1 mm. FIG. 10 is a graph showing a defect progress analysis result showing the relationship between time and initial defect size with the aspect ratio of the initial defect as a parameter by the defect tolerance evaluation apparatus according to the embodiment, showing the case where the initial defect depth is 2 mm. 10 is a graph showing the results of defect progress analysis showing the relationship between time and initial defect size with the aspect ratio of the initial defect as a parameter by the defect tolerance evaluation apparatus according to the embodiment, showing the case where the initial defect depth is 5 mm. FIG. 10 is a graph showing a defect progress analysis result showing the relationship between time and initial defect size with the aspect ratio of the initial defect as a parameter by the defect tolerance evaluation apparatus according to the embodiment, showing the case where the initial defect depth is 10 mm. 4 is a defect tolerance map showing the relationship between time and initial defect depth or initial defect half-length, with the aspect ratio of the initial defect as a parameter by the defect tolerance evaluation apparatus according to the embodiment; 4 is a defect tolerance map showing the relationship between an initial defect depth and an initial aspect ratio or an initial defect half-length, using the allowable defect size reaching time by the defect tolerance evaluation apparatus according to the embodiment as a parameter. It is a block diagram which shows the structure of a case evaluation apparatus among the defect tolerance evaluation apparatuses which concern on embodiment. FIG. 4 is a flow diagram showing a specific procedure of a case evaluation step in the defect tolerance evaluation method according to the embodiment; 7 is a graph for explaining an example of interpolation processing in an interpolation processing step of the case evaluation step according to the embodiment; FIG. 10 is a graph showing an example of assumed cases in the assumed case setting step of the case evaluation step according to the embodiment; FIG.

A defect tolerance evaluation apparatus and a defect tolerance evaluation method according to embodiments of the present invention will be described below with reference to the drawings. Here, portions that are the same or similar to each other are denoted by common reference numerals, and overlapping explanations are omitted. Here, the structures to be subjected to the defect tolerance evaluation according to this embodiment are, for example, equipment and members of nuclear power generation facilities. These include structures that make up the core, core internal structures such as a core shroud, and the like, but they may also be parts of other equipment or structures of a nuclear power plant. Moreover, it is not limited to nuclear power generation facilities, and can also target structures such as other power generation facilities.

FIG. 1 is a block diagram showing the configuration of a defect tolerance evaluation device according to an embodiment and the configuration of a defect tolerance map creation device thereof.

The defect tolerance evaluation device 10 has a defect tolerance map creation device 100 and a case evaluation device 200 . The defect tolerance evaluation device 10 is, for example, a computer system, but all or part of each element described below may be realized by separate devices.

First, the defect tolerance map creating apparatus 100 will be described below. The case evaluation device 200 will be described later.

For example, in a nuclear reactor facility, when a defect is found in a structure, the defect tolerance map creating apparatus 100 automatically adjusts the situation such that the evaluation period becomes the plant shutdown period when the impact evaluation is performed. In order to avoid this, it is an apparatus for calculating in advance the allowable remaining time with respect to the scale of various defects and preparing a defect allowance map.

The defect tolerance map creating apparatus 100 has a defect tolerance evaluation calculation section 110 , a defect tolerance evaluation storage section 120 , a defect tolerance evaluation input section 130 , a defect tolerance evaluation control section 140 and a defect tolerance evaluation output section 150 .

The defect tolerance evaluation calculation unit 110 has a defect size setting unit 111 , a stress intensity factor calculation unit 112 , a defect growth amount calculation unit 113 , a determination unit 114 , a defect tolerance map creation unit 115 and a detailed analysis unit 116 .

The defect dimension setting unit 111 sets a plurality of initial defects 2 (FIG. 2) necessary for creating the defect tolerance map 100a (FIGS. 10 and 11) in the defect tolerance map creation device 100. FIG. That is, a plurality of initial defects 2 are set as initial conditions for defect progression analysis necessary for creating the defect tolerance map 10a. The assumed minimum size of the initial defect is, for example, a semi-elliptical inner surface defect in the circumferential direction with a depth of 1 mm and a length of 10 mm, considering the detection limit size in inspection by visual inspection. . If there is a clear reason for setting, different minimum dimensions may be used.

In addition, the defect size setting unit 111 sequentially selects from the plurality of initial defects 2 and sets the initial condition in the repeated step for sequentially performing the defect progress analysis necessary for creating the defect tolerance map 10a. Set the initial defect 2 as . Further, the defect size setting unit 111 performs modeling such as setting of dimensions of a new defect in the next step in the defect progress analysis stage.

FIG. 2 is a conceptual cross-sectional view for explaining an initial defect 2 of an evaluation target portion 1 of the defect tolerance evaluation apparatus 10 according to the embodiment, and FIG. 3 is a cross-sectional view taken along line III-III in FIG.

Here, the part to be evaluated 1 includes both parts such as bolts and nuts, and specific parts of large structures such as reactor pressure vessels and core shrouds.

The cross-sectional shape of the initial defect 2 is assumed to be a semi-ellipse unless otherwise specified. However, the shape of the defect is not limited to a semi-ellipse, and may be any other technically appropriate shape based on the actual shape of the defect. Let the length of the semi-ellipse, ie, the width of the entrance of the opening, be 2c, and the depth, or depth, be "a". Here a/c is called the aspect ratio for the defect. These are functions of time or number of repetitions of loading. For example, if depth "a" is a function of time, it can also be written as a(t). The dimension of the initial defect 2 is therefore the value at time T=0 or the number of iterations n=0, eg, a(0) for the depth, which is denoted as "a ₀ ". Regarding the defect half-length "c", the case of the initial defect 2 is similarly expressed as "c ₀ ". Depth "a _{0 "} of the initial defect 2, defect half length "c ₀ ", aspect ratio (a ₀ /c ₀ ), etc. of the initial defect 2 are used as parameters based on the set minimum initial defect size. Set dimensions at appropriate dimension intervals.

Here, the dimensional information of the initial defect 2 required for evaluation/judgment may include depth, length, and shape if actual measurement by inspection is not possible, or if the measurement results themselves contain considerable uncertainty. It is also assumed that unknown parameters are included in the parameters. In such a case, it can be judged conservatively and technically appropriate based on the condition and geometric shape of the evaluation target part 1, required functions, past performance, etc., while utilizing available dimensional information. A defect size may be set.

The stress intensity factor calculator 112 calculates a stress intensity factor K. FIG. The stress intensity factor acting on a defect is calculated from the dimension of the defect and the external load and residual stress applied to the relevant portion. As a method for calculating the stress intensity factor, widely known methods such as simple evaluation formulas listed in standards such as the maintenance standards of the Japan Society of Mechanical Engineers and ASME Boiler & Pressure Vessel Code Section XI, Raju & Newman formulas, and influence function methods are used. A simple evaluation formula may be used. Alternatively, it may be calculated using FEM (Finite Element Method) analysis.

As the stress intensity factor K, the stress intensity factor K is calculated for each of the three modes of the in-plane open mode I, the in-plane shear mode II, and the out-of-plane shear mode III. However, for example, these three modes may be consolidated into Mode I and set to the safe side so that Mode I is representative. A case represented by mode I will be described below as an example. In this case, the stress intensity factor K is represented by the stress intensity factor _KI .

As shown in FIGS. 2 and 3, it is assumed that a stress _σ0 is applied to the site 1 to be evaluated. The stress intensity factor K _I for the defect of depth a at each time point may be calculated, for example, by the following equation (1).

Stress intensity factor K _I =σ ₀ ·(πa) ^1/2 (1)
The defect growth amount calculator 113 calculates the defect growth amount using the stress intensity factor _KI calculated by the stress intensity factor calculator 112 .

When the evaluation target portion 1 receives a repeated load, the defect growth amount is obtained, for example, by accumulating the defect growth rate (da/dn) obtained by the following equation (2).

da/dn=C ₁ (ΔK _I ) ^m (2)
Here, _ΔKI is a value obtained by subtracting the minimum value of the stress intensity factor _KI from the maximum value of the stress intensity factor _KI in one repeated cycle. Also, n is the number of cycles, _C1 is a conversion constant from the calculation result based on the stress intensity factor range to the defect growth rate, and m is a constant that should depend on the material of the evaluation target portion 1 .

When the evaluation target portion 1 is in a corrosive environment such as stress corrosion cracking (SCC), the defect growth rate is, for example, the defect growth rate (da/dt) obtained by the following equation (3). It is obtained by integrating over time. When calculating the crack growth amount per fixed step time, the step time may be arbitrary.

da/dt=C ₂ ·K _I ^j (3)
Here, _C2 is a conversion constant from the calculation result based on the stress intensity factor to the defect growth rate, and j is a constant that should depend on the material of the evaluation target portion 1 .

In calculating the defect progress amount, the determination unit 114 determines whether the defect size exceeds the allowable determination reference value, determines whether the analysis of all cases of the initial defect size has been completed, and determines whether the detailed analysis required case Determines whether or not it is specified. Determination of the defect size is made, for example, by determining whether or not the depth "a" or the defect half length "c" has reached a predetermined value. Other criteria include the remaining area obtained by subtracting the area of the defect from the cross section of the part to be evaluated, the applied stress, the stress intensity factor at the tip of the crack, and the like.

The defect tolerance map creation unit 115 creates the defect tolerance map 100a (FIGS. 10 and 11) based on the defect evolution amount calculation result for each initial defect size by the defect evolution amount calculation unit 113. FIG.

When the determination unit 114 determines that a detailed analysis required case is specified, the detailed analysis unit 116 basically performs detailed analysis on the specified case. That is, the detailed analysis unit 116 performs analysis using a combination of detailed analysis by the finite element method, probabilistic fracture mechanics evaluation, etc., in addition to a simple evaluation method according to the standard, and analyzes the conservativeness and continuation of the defect tolerance evaluation. Provides evaluation results such as the likelihood of driving safety. In the case evaluation step S40 (FIG. 13), which will be described later, this result is used in accordance with the likelihood of maintainability and safety indicated by the detailed analysis unit 116, and the optimum duration of continuous operation, the next and subsequent inspection plans, and maintenance plans. It can be used when setting methods, timings, and the like. In addition, the detailed analysis unit 116 directly performs the above-mentioned defect tolerance evaluation by analysis such as detailed analysis by the finite element method and probabilistic fracture mechanics evaluation instead of a simple evaluation method, and creates a defect tolerance map. can also

The defect tolerance evaluation storage unit 120 has a material property storage unit 121 , a parameter storage unit 122 , a defect progress amount storage unit 123 , a defect tolerance map data storage unit 124 , and a detailed analysis required case data storage unit 125 .

The material property storage unit 121 stores material property data such as the mechanical strength, elastic modulus, Poisson's ratio, and constants given by the formulas (2) and (3) of the material assumed to be the evaluation target part 1 .

The parameter storage unit 122 stores the dimensional data of the initial defect 2, the permissible criterion value of the defect size, the time course of the stress _σ0 applied to the evaluation target portion 1, and the like.

The defect growth amount storage unit 123 stores history data of the defect growth amount calculated by the defect growth amount calculation unit 113 for each size of the initial defect 2 . That is, the data of the change of the defect size (a, c) for each size (a ₀ , c ₀ , a ₀ /c ₀ ) of the initial defect 2 with respect to the change of t or n, for example, (a (t), c ( t)) or (a(n), c(n)) is stored and stored. Also, for _each size of each initial defect 2, the upper limit of the allowable range for the defect size in terms of design, e.g. The allowable defect dimension arrival time _tS , which is the arrival time, is also stored.

The defect tolerance map data storage unit 124 stores and stores data for the defect tolerance map 100a created by the defect tolerance map creation unit 115. FIG. The defect tolerance map data storage unit 124 also stores and stores output data in a format corresponding to the format displayed by the defect tolerance evaluation output unit 150 .

Here, the display method for quickly determining defect tolerance is not limited to a map-type graph. For example, it may be in the form of a numerical table or function, which indicates the relationship between the defect size and the allowable time. In the case of functions, by inputting defect dimensions evaluated by sizing, it is possible to accurately and instantly calculate and display the period during which continuous operation is possible due to defect tolerance. In addition, as other diagrams, the defect size and the period during which continuous operation is possible may be displayed in the form of a three-dimensional response curve. Additionally, these charts and functional forms may be combined to improve user convenience, both visually and accurately.

The detailed analysis required case data storage unit 125 stores and stores the analysis conditions for the analysis performed by the detailed analysis unit 116 for the detailed analysis required case. It also stores and stores the results of the detailed analysis performed by the detailed analysis unit 116 . In addition, the detailed analysis required case analysis condition is received by the defect tolerance evaluation input unit 130 as an external input together with the specification that the detailed analysis required case exists, and the detailed analysis required case data storage unit 125 specifies that the detailed analysis required case exists. Store and memorize together.

In order to effectively implement the defect tolerance evaluation, it is effective to quantitatively grasp and indicate the likelihood of conservativeness and safety of the evaluation results when deciding whether to continue operation based on the defect tolerance evaluation. Moreover, such a viewpoint is also effective in the case where permission is required for the determination of continued operation, etc., and in the case where permission is obtained in advance for the method and result of defect tolerance evaluation. As a method for solving such incidental problems, a method based on determinism is conceivable that shows the conservativeness of the evaluation by the simple evaluation method according to the standard by comparing it with the detailed analysis by FEM analysis. Also, for example, as an evaluation method based on probability theory, probabilistic fracture mechanics evaluation may be used. In this case, the defect tolerance determination index can be expressed in the form of the chart or function as the probability of destruction, leakage, or loss of function of the target device or structure.

The defect tolerance evaluation input unit 130 accepts external data necessary for the defect tolerance map creating apparatus 100 from the outside. The external data includes material property data stored in the material property storage unit 121, parameters stored in the parameter storage unit 122, designation of cases requiring detailed analysis, and the like.

The defect tolerance evaluation output unit 150 outputs the defect tolerance map 100a obtained by the defect tolerance map creation unit 115, detailed analysis results obtained by the detailed analysis unit 116, and the like.

The defect tolerance evaluation control unit 140 exchanges information between the defect tolerance evaluation calculation unit 110, the defect tolerance evaluation storage unit 120, the defect tolerance evaluation input unit 130, and the defect tolerance evaluation output unit 150, General control and management.

FIG. 4 is a flow chart showing the overall procedure of the defect tolerance evaluation method according to the embodiment. The defect tolerance evaluation method has a defect tolerance map creation step S10, a defect investigation step S30, and a case evaluation step S40.

FIG. 5 is a flow diagram showing a specific procedure of the defect tolerance map creation step S10 in the defect tolerance evaluation method according to the embodiment.

First, the site 1 to be evaluated is selected (step S11). The evaluation target portion 1 is read by the defect tolerance evaluation input unit 130 as an external input designating it. At this time, the defect tolerance evaluation input unit 130 may read not one evaluation target portion 1 but a plurality of evaluation target portions 1 and perform the following processing for each evaluation target portion 1 .

Next, the size of the initial defect 2 is set (step S12). Specifically, the defect dimension setting unit 111 sets a plurality of initial defects 2 necessary for creating the defect tolerance map 100a (FIGS. 10 and 11). Then, the defect size setting unit 111 sequentially selects one case of the initial defect 2 from among the plurality of initial defects 2 in the initial stage and when returning from step S17 described later, and the following step This is used as a condition for calculations after S13.

If the cross-sectional shape of the initial defect 2 is semi-elliptical as shown in FIG. 2, the length 2c and the depth a are set. Also, when the cross-sectional shape of the initial defect 2 is to be other than a semi-ellipse, a representative dimension that can specify the shape is set.

As will be described later, in order to finally create the defect tolerance map 100a, since analysis is performed for a plurality of cases of the initial defect 2, the setting of the length 2c ₀ and the depth a ₀ of the initial defect 2 Above, the minimum and maximum values and the width to be changed may be read by the defect tolerance evaluation input unit 130 . Alternatively, the defect size setting unit 111 may have its own minimum and maximum values and the size of the width to be changed, and use those values unless otherwise specified.

Next, the stress intensity factor K acting on the defect is calculated (step S13). Specifically, the stress intensity factor calculator 112 calculates the stress intensity factor K based on the shape and size of the defect 2 and the stress acting on the evaluation target portion 1 .

As the stress intensity factor K, as described above, the stress intensity factor can be calculated for each of the three modes of the in-plane open mode I, the in-plane shear mode II, and the out-of-plane shear mode III. However, as described above, the stress intensity factor _KI of mode I may be used by consolidating into mode I so that the evaluation is on the safe side, that is, the defect progression is evaluated severely. In this case, the stress intensity factor K _I can be calculated by Equation (1).

Next, the defect progress amount is calculated (step S14). Specifically, the defect growth amount calculation unit 113 calculates the defect growth amount using the stress intensity factor _KI calculated by the stress intensity factor calculation unit 112 . When the evaluation target portion 1 receives a repeated load, the defect growth rate (da/dn) is obtained from the equation (2). Further, when the evaluation target portion 1 is in a corrosive environment such as an SCC environment, the defect growth rate (da/dt) is obtained from the equation (3).

The defect growth amount in the next step is obtained by integrating the defect growth rate (da/dn) obtained by equation (2), or by time integration of the defect growth rate (da/dt) obtained by equation (3). Obtainable.

Next, modeling of the defect after defect development is performed (step S15). That is, the defect size setting unit 111 sets a new defect size based on the next step defect growth amount calculated by the defect growth amount calculation unit 113 in step S14.

Next, it is determined whether or not the defect size exceeds the allowable criterion value (step S16). Determination is performed by the determination unit 114 . When the determining unit 114 determines that the defect size does not exceed the allowable criterion value (step S16 NO), steps S13 to S16 are repeated.

When the determining unit 114 determines that the defect size exceeds the allowable criterion value (YES in step S16), the calculation of the defect progress amount is stopped, and the defect progress amount calculation result for the initial defect is the defect It is output to the defect progress amount storage unit 123 of the allowable evaluation storage unit 120, and the defect progress amount storage unit 123 accommodates and stores it. It should be noted that the results may be output to the defect progress amount storage unit 123 for each step of calculating the defect progress amount, and the defect progress amount storage unit 123 may store and store the results.

Next, the determination unit 114 determines whether or not all cases of the initial defect size have been completed (step S17). That is, the determination unit 114 determines whether or not the defect progress analysis has been performed for all the initial defect cases set by the defect size setting unit 111 . If the determination unit 114 determines that all cases of the initial defect size have not been completed (step S17 NO), the steps from step S12 to step S17 are repeated.

FIGS. 6 to 9 show defect evolution analysis results showing the relationship between time and initial defect depth, using the aspect ratio of the initial defect as a parameter by the defect evolution amount calculator 113 of the defect tolerance evaluation apparatus 10 according to the embodiment. FIG. 6 shows the initial defect depth _a0 of 1 mm, FIG. 7 shows the initial defect depth _a0 of 2 mm, FIG. 8 shows the initial defect depth _a0 of 5 mm, and FIG. A case where the defect depth _a0 is 10 mm is shown. In each case, the horizontal axis represents the actual time from the time of the initial defect state, that is, the time during which the load is applied.

In each of FIGS. 6 to 9, the vertical axis is the defect size at each time, the initial defect depth “a ₀ ” at time zero, and the upper limit is the allowable defect depth “as”. .

Here, the initial aspect ratio (a/c) used as a parameter is 0.1, 0.2, 0.5, 1.0 and 2.0.

In FIGS. 6 to 9, the defect dimension is the defect depth "a", but the defect dimension may be the defect half length "c". In this case, the upper limit is set to the allowable defect half length "cs" instead of the allowable defect depth "as".

Next, the defect tolerance map creating unit 115 creates the defect tolerance map 100a (step S18). The defect allowable map creating unit 115 determines the allowable defect associated with each dimension (a ₀ , c ₀ , a ₀ /c ₀ ) of the initial defect 2 from the defect progress amount data stored in the defect progress amount storage unit 123. The dimension arrival time _tS is read out and re-edited as data for the defect tolerance map 100a. That is, the set of (a ₀ ,c ₀ ,a ₀ /c ₀ ,t _s ) is accumulated. This result is stored in the defect tolerance map data storage unit 124 .

For example, the re-editing is performed by using the aspect ratio (a ₀ /c ₀ ) of the initial defect as a parameter, and as a combination of the initial defect depth a ₀ or the defect half length c ₀ and the corresponding allowable defect dimension reaching time _tS To edit. Alternatively, by using the allowable defect size arrival time _tS as a parameter, editing as a combination of the aspect ratio ( _a0 / _c0 ) or the defect half length _c0 of the initial defect and the corresponding allowable defect size arrival time _tS It's okay.

FIG. 10 shows the relationship between the allowable defect size arrival time _tS with the aspect ratio of the initial defect as a parameter and the defect depth a ₀ or the defect half length c ₀ by the defect tolerance evaluation apparatus 10 according to the embodiment. 10 is a defect tolerance map 100a showing analysis results; The horizontal axis is the allowable defect size arrival time _tS , and the vertical axis is the defect depth _a0 or the defect half length _c0 of the initial defect 2. FIG.

For example, when the defect depth a ₀ and the aspect ratio (a ₀ /c ₀ ) of the initial defect 2 are given, the allowable defect size arrival time _tS for the initial defect 2 is represented by can be obtained as a value.

FIG. 11 shows the relationship between the defect depth a ₀ and the aspect ratio (a ₀ /c ₀ ) or the defect half length c ₀ with the allowable defect size arrival time _tS by the defect tolerance evaluation apparatus 10 according to the embodiment as a parameter. is a defect tolerance map 100a showing a defect progress analysis result showing

The horizontal axis is the defect depth a ₀ of the initial defect 2, and the vertical axis is the aspect ratio (a ₀ /c ₀ ) or the defect half length c ₀ . The allowable defect dimension arrival time _tS is a parameter.

Given the defect depth a ₀ on the horizontal axis and the aspect ratio (a ₀ /c ₀ ) or the defect half length c ₀ on the vertical axis, the allowable defect size arrival time t _S at the intersection position is obtained.

Next, it is determined whether or not a detailed analysis required case is specified (step S19). That is, the determination unit 114 confirms whether or not the specification of the detailed analysis required case is stored in the detailed analysis required case data storage unit 125, and if the specification of the detailed analysis required case is stored, it is determined that the specification is present. judge.

If the determination unit 114 determines that a detailed analysis required case is specified (step S19 YES), the detailed analysis unit 116 performs analysis based on the analysis conditions stored in the detailed analysis required case data storage unit 125. , to conduct a detailed analysis. This analysis result is accommodated and stored in the detailed analysis required case data storage unit 125 .

If the determination unit 114 does not determine that the detailed analysis required case is designated (step S19 NO), the defect tolerance map creation step S10 is terminated.

FIG. 12 is a block diagram showing the configuration of the case evaluation device 200 of the defect tolerance evaluation device according to the embodiment. When the case evaluation apparatus 200 obtains defect information such as the measured value of the defect size and the defect position for a specific object, the evaluation target portion 1 having such a defect is evaluated in what manner thereafter. It provides judgment data as to whether to treat or automatically makes a judgment.

The case evaluation device 200 has a case evaluation calculation unit 210 , a case evaluation storage unit 220 , a case evaluation input unit 230 , a case evaluation control unit 240 and a case evaluation output unit 250 .

The case evaluation calculation unit 210 has an interpolation processing unit 211 , a remaining time derivation unit 212 , a case extraction unit 213 , a case evaluation unit 214 and a selection case determination unit 215 .

When the defect tolerance map 100a created by the defect tolerance map creation device 100 is used, the interpolation processing unit 211 performs interpolation when the measured value of the defect dimension deviates from the value of the data forming the defect map. I do.

The remaining time deriving unit 212 derives the allowable defect dimension arrival time based on the measured value of the defect dimension and using the defect tolerance map 100a. Here, the allowable defect size arrival time is the time when the defect size reaches the allowable criterion value of the defect size in the case of the measured defect size, assuming that the operation will be performed according to the operation plan up to that point. It shall say the time until Further, the remaining time derivation unit 212 derives the planned remaining time, which is the time up to the end of the plant operation period in the initial plan, based on the operation plan stored in the initial operation plan storage unit 221, which will be described later. Here, the allowable defect size reaching time may be longer than the planned remaining time or shorter than the planned remaining time. The allowable defect size arrival time and the planned remaining time are collectively called the allowable remaining time.

Based on the allowable defect size arrival time and the planned remaining time derived by the remaining time deriving unit 212, the case extracting unit 213 sets assumed cases that can be assumed as future measures. Specifically, a hypothetical case is extracted from hypothetical cases stored in the hypothetical case database 222, which will be described later, based on the allowable defect size arrival time and the planned remaining time.

The case evaluation unit 214 calculates an evaluation function value for each case extracted by the case extraction unit 213 based on the evaluation function. That is, it provides data for determining how to deal with the defective evaluation target portion 1 thereafter.

The selected case determination unit 215 determines a selected case from the evaluation function value for each assumed case calculated by the case evaluation unit 214 . In other words, the optimum hypothetical case is selected as to how the evaluation target portion 1 having the defect should be treated thereafter.

The case evaluation storage unit 220 has an initial operation plan storage unit 221 , an assumed case database 222 and an element cost database 223 .

The initial operation plan storage unit 221 stores an operation plan of a plant having an object, such as a nuclear power plant, as an initial operation plan. The operation plan is a basic plan such as startup timing, output level during operation, operation period, inspection period, inspection period, shutdown period, shutdown period, plant final shutdown period, and the like.

The hypothetical case database 222 is a database that accumulates and stores conceivable corresponding cases according to the area of the allowable remaining time such as the allowable defect size reaching time and the planned remaining time. Assumed cases include, for example, a case in which a defect in the evaluation target portion 1 is treated immediately or the relevant portion is replaced, or a case in which the operation plan is continued by performing periodic inspection monitoring at predetermined intervals in the future. .

Element cost database 223 contains cost data for basic elements for evaluating the cost for each hypothetical case contained in hypothetical case database 222 . The basic elements include, for example, each inspection cost during the service period, profit for continued operation per unit period, countermeasure cost per defect, and the like. However, each inspection cost during the service period and countermeasure cost per defect need to be a database in a form dependent on each condition. Note that the cost data may be relative values instead of absolute values. The basic elements include, for example, costs for periodic inspections according to inspection grades, and costs for each object and each location where defects occur for treatment of defects.

Case evaluation input unit 230 accepts external data required by case evaluation device 200 . The external data includes the initial operation plan of the plant stored in the initial operation plan storage unit 221, the content of the assumed case stored in the assumed case database 222, and the cost data of each of the assumed case components stored in the element cost database. etc.

The case evaluation output unit 250 outputs the case evaluation result of the case evaluation unit 214 and the selected cases determined by the selected case determination unit 215 .

The case evaluation control unit 240 provides overall control over the exchange of information between the case evaluation calculation unit 210, the case evaluation storage unit 220, the case evaluation input unit 230, and the case evaluation output unit 250, and the progress of each. manage.

FIG. 13 is a flow diagram showing a specific procedure of the case evaluation step S40 in the defect tolerance evaluation method according to the embodiment.

The defect investigation step S30 is a step of identifying defects and defect positions, measuring defect dimensions, and acquiring defect information such as defect positions and defect dimensions for a specific object.

In the case evaluation step S40, first, the allowable residual period is derived (step S41). Specifically, first, the interpolation processing unit 211 uses the defect tolerance map 100a created in the defect tolerance map creation step S10 based on the defect information about the object obtained in the defect investigation step S30, Interpolate.

FIG. 14 is a graph illustrating an example of interpolation processing in the allowable remaining time derivation step S41 of the case evaluation step S40 according to the embodiment.

Now, for example, assume that the defect dimension obtained in the defect investigation step S30 has a depth _a0 value of _a01 and an aspect ratio _a0 / _c0 value of 0.8. In this case, the intersection of the straight line L1 having the vertical axis value _a01 and the curve of " _a0 / _c0 =0.5" in the defect tolerance map 100a is P5, and the straight line L1 and " _a0 / c ₀ =1.0” is defined as P10. A point P8 with an aspect ratio of 0.8 may be determined by interpolation between the intersection point P5 with an aspect ratio of 0.5 and the intersection point P10 with an aspect ratio of 1.0. It should be noted that the interpolation may be linearly set based only on points P5 and P10, and the intersection points with the curves for aspect ratios of 0.1, 0.2, and 2.0 are also Including, it may be interpolated in a curved line from the relationship between the aspect ratio and each allowable defect size arrival time _ts . In this way, the allowable defect size arrival time _ts0 of the intersection point P8 is obtained. It should be noted that the allowable defect size arrival time _ts0 may be obtained conservatively using the nearest curve on the short time side without depending on the interpolation process.

Next, the remaining time deriving unit 212 derives the allowable defect dimension arrival time according to the above-described procedure based on the measured value of the defect dimension, and the planned remaining time based on the operation plan stored in the initial operation plan storage unit 221. to derive

Next, an assumed case is set (step S42). That is, the case extraction unit 213 extracts the corresponding assumed case from the assumed case data stored in the assumed case database 222 based on the allowable defect size arrival time and the planned remaining time.

FIG. 15 is a graph showing an example of assumed cases in the assumed case setting step of the case evaluation step according to the embodiment. Two cases, hypothetical case A and hypothetical case B, are shown.

Assumed case A is a case in which, following the confirmation of a defect in the target object, countermeasure construction is first carried out, and then the operation of the plant is to be restarted. As a result, the part that differs from the initial plan is the construction plan including permits and licenses up to the countermeasure construction, material procurement, preparation for construction such as manufacturing, and the implementation of construction. However, after the construction work is completed, the plant can be operated until the end of the initially planned plant operation period.

Assumed case B is, for example, a case in which the planned remaining period is not so long, ie, the life of the plant is approaching, and long-term operation cannot be expected even if countermeasures are taken. In this case, it is conceivable to operate the plant only for the allowable defect dimension arrival time without performing countermeasure construction. In this case, no countermeasure work is required. However, it is conceivable to strengthen monitoring as a condition for continuing plant operation. For example, it is conceivable that the inspection is performed at each periodic inspection of the plant, or, as shown in FIG. 15, at an intermediate time point between each periodic inspection. As hypothetical cases to be stored in the hypothetical case database 222, a plurality of examination frequencies may be prepared.

Next, the evaluation function value for each case is calculated (step S43). Here, the evaluation function is for determining the most appropriate assumed case, and is a function for deriving an evaluation value for each assumed case. Evaluation viewpoints may include safety, social reliability, economy, etc., and may be a function that incorporates all of these viewpoints.

Satisfying safety and social reliability is now a major premise, and if all hypothetical cases are at least satisfactory from these points of view, economic efficiency may be used as an index for comparison. In this case, the case evaluation unit 214 uses the cost data stored in the element cost database 223 to calculate the evaluation function value for each case extracted by the case extraction unit 213 .

The evaluation function P may be calculated using, for example, the following formula (4).

P=ΣN _k C _k (4)
where N _k is the number of k-th components, C _k is the unit cost of the k-th component, Σ is the sum of k from 1 to K, and K is the number of types of components. . The unit cost _Ck is contained and stored in the element cost database 223 .

In addition, when evaluating the cost of a hypothetical case, when the cost is considered to be the sum of the cost of a typical physical quantity and the cost of an action, It means an element that can be treated as a unit.

Also, the evaluation function P is assumed to integrate deviations from the initial plan of the plant. Therefore, _CK can take both positive and negative values. If the cost increases relative to the plant's original plan, _CK has a negative value, and if the cost decreases relative to the plant's original plan, _CK has a positive value.

When the detailed analysis required case is specified, the detailed analysis unit 116 executes the detailed analysis execution step S20 of the defect allowance map creation step S10, and the detailed analysis required case data storage unit 125 stores and stores the data. Invoke the analysis results that have been used, and consider the likelihood evaluation results for maintainability and security. Specifically, for example, in cases where the likelihood of conservativeness and safety is low, the inspection interval is further shortened in the assumed case to increase the degree of monitoring, or the absolute value of the negative value is extremely large. to lower the priority or remove it from the selection case candidates to be described later.

Alternatively, as a result of the detailed analysis, if it is confirmed that the likelihood of conservativeness and safety is higher than the standard calculation, etc., it will be prepared as supporting information for the plan.

Examples of assumed case A and assumed case B shown in FIG. 15 are as follows.

Assumed case A consists of implementation of countermeasure construction (assumed case A1) and preparation for countermeasure construction and plant shutdown (assumed case A2). Each count is one. Concerning the unit cost for implementing the countermeasure construction, it is preferable to accumulate the component cost for each target object and the occurrence site thereof.

Assumed case B includes the implementation of inspections for monitoring (assumed case B1) and shortening of the plant operation period (assumed case B2). The number of times of assumed case B1 is 10 in the case of FIG.

Next, each case is compared and a selected case is determined (step S44). Specifically, in step S43, the selected case determination unit 215 determines the selected cases based on the evaluation function values calculated by the case evaluation unit 214 for each set assumed case. Unless there are special circumstances, basically, the assumed case with the largest evaluation function value is the selected case. The above is performed by the case evaluation device 200 .
Next, specific measures for selected cases are examined (step S50). That is, examination by a normal human system is performed.

As described above, according to the present embodiment, it is possible to provide a defect tolerance evaluation apparatus and a defect tolerance evaluation method that can quickly determine what to do when a defect is detected.

[Other embodiments]
Although the embodiments of the present invention have been described above, the embodiments are presented as examples and are not intended to limit the scope of the invention.

For example, in the embodiment, the defect tolerance evaluation is performed by first setting the initial defect dimension and obtaining the allowable defect dimension arrival time for the initial defect dimension, but the present invention is not limited to this. For example, there is a method of performing inverse analysis on the allowable defect size corresponding to the defect allowable standard to obtain the initial defect size. Alternatively, a method of obtaining the initial defect size as a response surface by inverse analysis with respect to a given allowable defect size reaching time may be used.

Moreover, you may combine the characteristic of each embodiment. In addition, the embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention.

The embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and its equivalents.

1 Evaluation target part 2 Initial defect 10 Defect tolerance evaluation device 100 Defect tolerance map creation device 100a Defect tolerance map 110 Defect tolerance evaluation calculation unit 111 Defect size setting unit 112 Stress Enlargement factor calculation unit 113 Defect progression amount calculation unit 114 Determination unit 115 Defect tolerance map creation unit 116 Detailed analysis unit 120 Defect tolerance evaluation storage unit 121 Material property storage unit 122 Parameters Storage unit 123 Defect progression amount storage unit 124 Defect tolerance map data storage unit 125 Detailed analysis required case data storage unit 130 Defect tolerance evaluation input unit 140 Defect tolerance evaluation control unit 150 Defect tolerance Evaluation output unit 200 Case evaluation device 210 Case evaluation calculation unit 211 Interpolation processing unit 212 Remaining time derivation unit 213 Case extraction unit 214 Case evaluation unit 215 Selected case determination unit 220...Case evaluation storage unit 221...Initial operation plan storage unit 222...Assumed case database 223...Element cost database 230...Case evaluation input unit 240...Case evaluation control unit 250...Case evaluation output unit

Claims (5)

a defect size setting unit that sequentially sets the size of the initial defect assumed in the evaluation target portion;
a defect growth amount calculation unit that calculates a defect growth amount based on the size of the initial defect;
a determination unit that determines whether a predetermined allowable defect size has been reached;
a defect tolerance map creating unit for creating a defect tolerance map showing the relationship between the sequentially set dimensions of the initial defects and the allowable defect dimension arrival time, which is the time to reach the predetermined allowable defect dimension;
An initial operation plan storage unit that stores the initial operation plan;
A hypothetical case database that stores hypothetical cases assumed as a response when a defect is detected;
Deriving the allowable defect size arrival time using the defect tolerance map based on the size of the initial defect, and the remaining plan until the end of the plant operation period according to the initial operation plan stored in the initial operation plan storage unit a remaining time derivation unit for deriving time;
a case extracting unit that extracts a hypothetical case from the hypothetical case database based on the allowable defect dimension arrival time and the planned remaining time;
an element cost database that stores cost data about the elements that make up the hypothetical case;
a case evaluation unit that calculates an evaluation function value using the cost data stored in the element cost database for each of the assumed cases extracted by the case extraction unit;
a selected case determining unit that determines a selected case from among the assumed cases extracted by the case extracting unit based on the evaluation function value;
A defect tolerance evaluation device comprising: 3. The defect tolerance map is characterized in that the relationship between the defect depth or the defect half length of the initial defect and the time required to reach the dimension of the allowable defect is shown using the aspect ratio of the initial defect as a parameter. 2. The defect tolerance evaluation device according to 1. 2. The defect tolerance map shows the relationship between the aspect ratio or the defect half length of the initial defect and the defect depth of the initial defect, using the allowable defect dimension arrival time as a parameter. The defect tolerance evaluation device according to . 4. The defect tolerance evaluation apparatus according to any one of claims 1 to 3, further comprising a detailed analysis unit that performs detailed analysis based on designation of detailed analysis requirements. an initial defect dimension setting step of sequentially setting the dimensions of the initial defect assumed in the evaluation target portion;
a defect growth amount calculation step of calculating a defect growth amount based on the size of the initial defect;
a determination step of determining whether a predetermined defect size has been reached, and repeating the defect growth amount calculation step when the defect size has not been reached;
a defect tolerance map creating step of creating a defect tolerance map in which the relationship between the sequentially set initial defect dimensions and the allowable defect dimension arrival time, which is the arrival time to the predetermined defect size, is organized;
Based on the dimensions of the initial defect, the defect tolerance map is used to derive the allowable defect dimension arrival time, and the planned remaining time until the end of the plant operation period according to the initial operation plan stored in the initial operation plan storage unit. a residual time derivation step to derive;
a case extraction step of extracting a hypothetical case from a hypothetical case database based on the allowable defect size arrival time and the planned remaining time;
a case evaluation step of calculating an evaluation function value using a costator stored in an element cost database for each of the assumed cases extracted in the case extraction step;
a selected case determination step of determining a selected case from the assumed cases extracted in the case extraction step based on the evaluation function value;
A defect tolerance evaluation method characterized by having

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