KR20150044032A - A method for simulating the behavior of nuclides in an HLW repository system using Compartments - Google Patents

Abstract

A method for simulating the behavior of nuclides in an high-level waste (HLW) repository system using compartments according to the present invention comprises: a segmentation step where the entire area of an HWL repository system is segmented into numerical analytic areas and successive analytic areas; a modeling step where the behavior of nuclides within the numerical analytic areas and the successive analytic areas is modeled respectively according to possible outflow scenarios; a calculation step where the travel distance of the nuclides between the areas segmented from the segmentation step are calculated by applying the model acquired from the modeling step.

Description

Technical Field [0001] The present invention relates to a method for simulating the behavior of a radionuclide in a radioactive waste disposal system according to an analysis region division,

The present invention relates to a new method for simulating the behavior of a radionuclide in a radioactive waste disposal system, and more particularly, to a method for modeling a radioactive waste disposal system, The present invention relates to a method for simulating the behavior of a radionuclide in a radioactive waste disposal system capable of enhancing the safety and performance evaluation efficiency of the radioactive waste disposal system through a technique of simulating radioactive waste disposal, and improving accuracy.

In general, the methodology that simulates the propagation and movement of radionuclides from radioactive waste repositories requires specialized modeling techniques to maintain high reliability and low uncertainty.

In addition, we propose a methodology that enables detailed deterministic evaluation of input data with high reliability. In addition, we can make a probabilistic evaluation that can quantitatively evaluate such uncertainty when input data is uncertain, A conceptual model should be developed first through analyzing and synthesizing the various elements, events and processes (FEPs) that are involved in the outflow and movement and then quantitatively evaluating the outcome of the project. Based on this, a mathematical model capable of actual quantitative evaluation should be developed.

However, the method of simulating the propagation and movement of the radionuclides discharged from the conventional radioactive waste repository is an analytical method in which the system is simply modeled, or an extremely simplified numerical method, and a high quality object oriented commercial development tool There is a problem that the simulation evaluation method using the more detailed and reliable model is hardly developed.

Therefore, a method for solving the above problems is required.

Korean Patent No. 10-0930681

Disclosure of Invention Technical Problem [8] The present invention is directed to a method for simulating the propagation and migration of radionuclides discharged from a radioactive waste repository to a geological environment and a human environment, To provide a more detailed and reliable method for simulating radionuclide behaviors.

The solution of the present invention is not limited to those mentioned above, and other solutions not mentioned can be clearly understood by those skilled in the art from the following description.

A method for simulating the behavior of a radionuclide in a radioactive waste disposal system according to the present invention is a method for simulating the behavior of a radionuclide in a radioactive waste disposal system, A modeling step for modeling the behaviors of the radionuclides in the numerical analysis area and the continuous analysis area, respectively, and a modeling step for applying the modeling obtained in the modeling step, according to the possible outflow scenarios, And calculating an amount of movement of the radionuclide between each of the regions divided in the dividing step.

Between the modeling step and the computing step, a matching step of matching the results of modeling the behavior of the radionuclides in the numerical analysis area acquired in the modeling step and the modeling results of the radionuclides in the continuous analysis area may be further included .

The matching step may include calculating a mass transfer rate of the radionuclide in the continuous analysis region.

And wherein the mass transfer rate of the radionuclide in the continuous analysis region,

Can be calculated using the following equation.

Wherein the radioactive waste disposal system includes a root zone, a primary zone, and an ecosystem, wherein the partitioning step divides the root zone into one or more numerical analysis zones, and wherein the primary zone and the ecosystem are divided into one or more continuous analysis zones Can be divided.

Wherein the outflow scenario considered in the modeling step includes a well excavation scenario, wherein the dividing step includes setting a capture zone where a groundwater flowing into a well excavated in the entire area of the radioactive waste disposal system flows, The capture zone can be divided into successive analysis regions.

The outflow scenario considered in the modeling step also includes at least one of a colloidal scenario and a chelating agent scenario, and the operation step may calculate the amount of movement of the radionuclide in consideration of the colloidal scenario and the chelating agent scenario .

Further, between the dividing step and the modeling step, a subdividing step of finely dividing the divided numerical analysis area and the continuous analysis area may be further included.

According to the present invention, the method of radionuclide movement simulation in the radioactive waste disposal system according to the present invention is more reliable for complex systems in which various media and mechanisms coexist, such as a radioactive waste repository, reduces uncertainty, This approach has several advantages.

In addition, since the entire disposal system can be divided into a numerical analysis area and a continuous analysis area, the behavior of the radionuclide can be simulated, so that the accuracy and reliability are higher than those of the conventional general numerical analysis method alone.

It also has the advantage of being able to simulate the behavior of radionuclides while maintaining rapid and high accuracy even in the case of various outflow scenarios.

In addition, it is possible to develop related programs as modeling and evaluation tools that can be used as a deterministic and probabilistic evaluation tool to check the safety and performance of disposal systems. At the same time, probabilistic evaluation is carried out in consideration of uncertainties of major parameters, It is possible to present the reliability of the proposed method, and it is possible to present the importance and priority of the major input factors through the sensitivity analysis evaluation.

The effects of the present invention are not limited to those mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram showing the entire area of a radioactive waste disposal system.
2 is a flowchart illustrating steps of a method for simulating a radionuclide behavior in a radioactive waste disposal system according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating the behavior of radionuclides in the divided analysis regions in the method of simulating the radionuclide behavior in the radioactive waste disposal system according to the embodiment of the present invention.
FIG. 4 is a diagram illustrating a capture zone as a groundwater flow region flowing into a well excavated adjacent to a radioactive waste repository in a radioactive waste disposal system in a radioactive waste disposal system according to an embodiment of the present invention; FIG.
FIG. 5 is a flowchart illustrating a method for simulating radionuclide behaviors in a radioactive waste disposal system according to an embodiment of the present invention, wherein a predetermined region is divided into a numerical analysis method and a continuous analysis method As shown in FIG.
6 is a flowchart illustrating a method of simulating radionuclide behaviors in a radioactive waste disposal system according to an embodiment of the present invention when an earthquake occurs and the flow rate of the groundwater is irregular, And a continuous analysis method, respectively.

Hereinafter, a method for simulating radionuclide behavior in a radioactive waste disposal system according to the present invention will be described in detail with reference to the drawings.

Fig. 1 is a diagram showing the entire area of the radioactive waste disposal system 1. Fig.

As shown in FIG. 1, the radioactive waste disposal system 1 includes a near-field region 100 including an artificial barrier consisting of a disposal site 10 and a surrounding structure disposed within the underground disposal host rock, And an ecosystem 300 including a human living zone on the surface of the earth.

The disposal site 10 is constructed in the mother rock, and the disposal container made of cement or concrete box containing the waste is disposed in the disposal site 10. When the waste is completely disposed of and the repository 10 is closed, the groundwater is introduced into the repository 10 for a long period of time, and the groundwater is introduced into the vessel as the disposed waste vessel is damaged. And then flows out between the container and the repository 10 and then through the groundwater to the repository 10 through the arcuate zone 100 where the artificial barrier and the repository 10 are present, 200), and again to an ecosystem (300) where human activities are performed.

In the radioactive waste disposal system 1, the arsenic region 200 including the natural medium as the mother rock in which the repository 10 is located as well as the near-field region 100 near the disposal site 10 has a complex geological system There are various and unpredictable groundwater flows through this medium.

The diffusion, dispersion and entrainment of nuclides due to the release of nuclides by groundwater flow, delay and acceleration by adsorption and desorption with materials in the medium of nuclides and colloid or chelating agents due to geochemical factors around the repository , And the diffusion movement into the underground media in a direction not related to the flow of the groundwater is complicatedly interlinked.

The outflow of radionuclides in the medium and the radioactive waste disposal system 1 should be evaluated with reliability and quantitatively considering the performance of the repository 10 and the influence of the human environment. In fact, there is a problem that the simulation is not easy. In addition, it is not easy to evaluate with various natural and artificial deformation and spill scenarios even in the well-known underground environment.

Conventional methods for solving this problem generally make it easier to interpret the radioactive waste disposal system 1 even if the reliability is low and the uncertainty increases. However, even if this simplification is taken into consideration, there are limitations in evaluating the outflow of simultaneous radionuclides related to various aspects of the radioactive waste disposal system (1), its migration, and its impact on the human environment.

To this end, in the present invention, the whole area of the radioactive waste disposal system 1 is divided into a numerical analysis area and a continuous analysis area, and a method of simulating radionuclide behavior between these areas is used. Since the divided region includes a continuous analysis region in addition to the numerical analysis region, it can accurately simulate the behavior of complex radionuclides through various media, and can also consider various leaking scenarios together. In the following, we explain this in detail.

2 is a flowchart illustrating steps of a method for simulating a radionuclide behavior in a radioactive waste disposal system according to an embodiment of the present invention.

As shown in FIG. 2, the method for simulating the radionuclide behavior in the radioactive waste disposal system according to the embodiment of the present invention is characterized in that the entire area of the radioactive waste disposal system is divided into a numerical analysis region and a continuous analysis region A modeling step (S20) of modeling the behavior of the radionuclides in the numerical analysis area and the continuous analysis area, respectively, according to the possible outflow scenarios (S20); and a modeling step And calculating an amount of movement of the radionuclide between each of the regions divided in the dividing step (S30).

In addition, between the dividing step (S10) and the modeling step (S20), a subdividing step (S15) for finely dividing the divided numerical analysis area and the continuous analysis area may be further included.

Between the modeling step (S20) and the calculating step (S30), a modeling result of the radionuclide in the numerical analysis area obtained in the modeling step and a modeling result of the radionuclide in the continuous analysis area are matched to each other Step S25 may be further included.

First, in the dividing step (S10), the entire area of the radioactive waste disposal system is divided into a predetermined number of areas. That is, the radioactive waste disposal system is divided into a plurality of regions, and then the behavior of the radionuclides between these regions is modeled.

Each of the divided regions may be either a numerical analysis region or a continuous analysis region. The numerical analysis region is suitable for describing diffusion and migration by advection, and the continuous analysis region is suitable for describing mass transfer by advection and dispersion.

On the other hand, the numerical analysis area and the continuous analysis area can be appropriately set according to the characteristics of each facility, the topography and cracking characteristics of the facility area, the outflow of generated nuclides, the expected path, and the like. However, for the accuracy of the analysis, the numerical analysis region is applied to artificial structures having a relatively clear behavior of radionuclides and a low probability of occurrence of variables, and the continuous analysis region is complicated in the behavior of radionuclides, It is desirable to apply to natural structures and surface environments where the probability of occurrence of variables is high.

Accordingly, the partitioning step S10 may divide the root-mean-sized region of the radioactive waste disposal system into one or more numerical analysis regions, and divide the original region and the ecosystem into one or more continuous analysis regions.

Alternatively, however, it should be understood that the segmented region of the near-field region may include one or more continuous analysis regions, and the original region and the ecosystem may include one or more numerical analysis regions. This can be suitably set by the environment and other variables of the relevant radioactive waste disposal system.

The re-dividing step (S15) is a step of finely dividing the divided numerical analysis area and the continuous analysis area. That is, each of the divided regions can be further subdivided. In this case, when the numerical analysis region is subdivided, the subregion may include a continuous analysis region, and when the continuous analysis region is subdivided, the subregion may include a numerical analysis region.

In the modeling step S20, the behaviors of the radionuclides in the numerical analysis region and the continuous analysis region are respectively modeled according to the possible outflow scenarios.

As described above, the root-mean-square region can be divided into numerical analysis regions. Typically, the repository is disposed of with the waste contained in a container, where the numerical analysis area assumes that the wastes contained in the same kind of container are disposed together in an equivalent concrete box corresponding to a single virtual one waste container . At this time, one representative model of the waste representative container in each disposal field is modeled to correspond to each one of the source items.

The term "source term" means a source of radiation emitted from a nuclear facility and is used in various places as a value required for evaluating the exposure dose. In general, the term "source" refers to the type and amount of radionuclides emitted from the facility as input at the starting point of the transition path in the environment. In the case of reprocessing facilities, it may be the target of radioactive nuclear waste that is emitted from the exhaust pipe at the time of an accident or the waste liquid discharge outlet.

On the other hand, the original area and the ecosystem can be divided into continuous analysis areas. In this case, the rock cracking medium defines the moving distance, the moving surface, the dispersion coefficient, and the diffusion into the matrix of the radionuclide in the medium. In order to obtain a moving section, the width of the crack or the flow width of the actual contaminated groundwater, Can be considered.

In this way, the natural barrier in the parent rock around the disposal site can be modeled as a cracking medium with plate cracks, so that groundwater flows along this cracking medium, . At the same time, the matrix diffusion to the cracks and the crack wall is performed, and at the same time, the delay effect due to the adsorption / desorption reaction with the medium of the nuclide can be considered.

Meanwhile, the modeling of the numerical analysis area and the continuous analysis area may be performed using a commercial program. The commercial program may include a program such as Goldsim which can model the flow of various flow elements by a simulated technique. In addition, in the case of the gold shim, modeling of each area can be performed using object-oriented moving simulation tools such as a cell pathway and a pipe pathway included in the program.

In the case of the Cell Pathway, the flow between the points can be modeled and thus can be used for modeling the numerical analysis area. In the case of the pipe pathway, the continuous flow can be modeled, and thus can be used for modeling the continuous analysis region.

After the modeling step S20 described above, a matching step S25 may be performed, and the matching step S25 may include a modeling result of the behavior of the radionuclides in the numerical analysis region obtained in the modeling step S20, And the modeling results of the radionuclides in the analysis area are matched with each other.

The reason for doing this is to ensure that the modeling results of the discontinuous numerical analysis region and the modeling results of the successive continuous analysis region are compatible with each other. This is to calculate the mass transfer rate of the radionuclide in the continuous analysis region so that the modeling results of the numerical analysis region and the continuous analysis region can be compatible with each other.

The compatibility of modeling results with mass transfer rates is necessary to ensure continuity of radionuclide migration between modeling results between two mathematically and physically different domains. In order to simulate the movement of materials, This is because it is most advantageous to store the masses in order to link them.

And the mass transfer rate of the radionuclide in the continuous analysis region can be calculated by the following equation.

Accordingly, it is possible to easily calculate the radionuclide migration amount between the numerical analysis region and the continuous analysis region in the calculation step S30.

FIG. 3 is a diagram illustrating the behavior of radionuclides in the divided analysis regions in the method of simulating the radionuclide behavior in the radioactive waste disposal system according to the embodiment of the present invention.

As shown in FIG. 3, in the calculation step S30, the amount of movement of the radionuclide between each of the divided analysis regions is calculated. For example, radionuclides flowing out through groundwater or the like behave from the respective numerical analysis regions a1 and a2 of the near-field region 100 to the respective continuous analysis regions a3 and a4 of the original region 200, (A5, a6) of the ecosystem 300, respectively.

Thus, it is possible to model the behavior of radionuclides in the entire radioactive waste disposal system by calculating the amount of radionuclide migration between the respective analysis regions.

In addition to the behavior of common radionuclides, a variety of runoff scenarios can occur. Hereinafter, a method of modeling the behavior of radionuclides will be described taking these factors into consideration.

4 is a schematic diagram of a radioactive waste disposal system according to an embodiment of the present invention. In the radioactive waste disposal system according to an embodiment of the present invention, a capture zone z, which is a groundwater flow area flowing into a well w1 excavated adjacent to a radioactive waste repository, Fig.

As shown in Fig. 4, various wells can be excavated from the surface of the earth in the radioactive waste disposal system. In general, when a deep well (w1) reaching the depth of the bottom of the repository (10) is excavated near the repository (10), the well water is taken through the deep well (w1) and used as drinking water. At the same time, And livestock, so that a large amount of the radioactive nuclei can be transferred to the ecosystem 300 through the well w1. This eventually becomes the de facto worst case scenario for the regeneration pathway of the concentrated exposure group associated with well excavation in a radioactive waste disposal system.

And the waters w2 that are more distant from the repository 100 are transported to the ecosystem 300 through relatively less nuclear paper wells w2 and the remainder are transported through the repository 10, It can be expected that it will be transferred to the ecosystem 300 through the rock mass through the region 200, and a methodology for detailed and proper modeling is required.

In addition, if the well w2 is excavated from the repository 10, the excavation depth of the well w2 becomes very high. If the repository 10 is actually located on a hill, the radioactive waste disposal system Since the surface of the earth is a gentle slope toward the sea, it is difficult to expect that the well (w2) excavated below these hills will be excavated in the deep layer, even though there is no aquifer whose boundary with the rock layer is not clearly distinguished And modeled as a shallow well (w2).

Meanwhile, a portion of the radionuclide that has passed through the groundwater 10 from the repository 10 enters the wells (w1, w2) along with the flow of the groundwater, while the remainder continues to flow and eventually goes out to sea. We introduce the concept of zone (z, Capture zone).

If the pumping is not performed in the wells (w1, w2), the groundwater flow will not change, but if the pumping is performed, the groundwater flow is divided into the areas (f1, f2, f3) . Therefore, in the present invention, a region where flow of groundwater is changed by pumping is defined as a capture zone z.

Even if there is pumping by the capture zone z, the outside of this range has no effect on the pumping, but the inside of the boundary represents the area to be affected by the pumping, so that all the groundwater Can be modeled as being all pumped by wells w1, w2.

In this case, the dividing step S10 may divide the capture zone z into a continuous analysis region.

In addition to well excavation scenarios, the leaking scenarios considered in the modeling step may include at least one of a colloidal scenario and a chelating agent scenario.

The calculating step S30 may calculate the amount of movement of the radionuclide in consideration of the colloidal scenario and the chelating agent scenario.

In natural groundwater, various kinds of colloid particles such as oxides, hydroxides, organic acids, and mineral particles can exist, and most of the colloids are charged on the surface, and adsorb metal ions and the like.

In addition, decontamination compounds such as cellulosic decomposition compounds and EDTA can be present along with the waste in the waste disposed as the main complex, usually containing less than 0.006 wt% by weight, but they also affect the movement of the nuclide .

As a chelating agent as such a complexing agent, it is regarded as chemically and physically equivalent to a colloid. However, considering the irreversible nature of adsorption, unlike colloid, it is considered that the half-lives of colloid and chelator are different from each other, Modeling can be done.

FIG. 5 is a graph showing a result of analyzing a divided region by a numerical analysis method and a continuous analysis method, respectively, when the flow rate of the groundwater is constant in the radioactive waste disposal system according to the embodiment of the present invention And FIG. 6 is a graph showing the results of a numerical analysis method and a continuous analysis method of a radioactive waste disposal system according to an embodiment of the present invention when a flow rate of groundwater is irregular due to an earthquake, The results are shown in FIG.

In the case of FIG. 5, the flow rate of the groundwater is constant because no other outflow scenario occurs. In this case, both the numerical analysis method and the continuous analysis method agree with each other irrespective of the number of divided areas.

However, in the case of Fig. 6, the flow rate of the groundwater becomes largely irregular when the earthquake scenario occurs. In this case, it can be seen that the numerical analysis method greatly changes its behavior according to the number of 2, 10, and 20 regions. In case of the continuous analysis method, 1, 2, 3, 5, 10, 20 It can be seen that the behavior change increases with the number of regions.

The breakthrough curve at which the flow rate suddenly increases at the time of the earthquake, that is, at 0.5 years, shows a steep increase in the peak and nearer accuracy, while using more continuous analysis areas, But it does not converge to a constant value.

In this case, since the area under the breakwater curve is always constant, the peak increases with the increase of the flow rate due to the influence of the earthquake, and the shape of the lower part of the end is not converged to a constant shape, none.

This is because, if the continuous analysis method is a physical medium having the same nature as the numerical analysis method, it is possible to obtain a more accurate solution by increasing the number of divided regions not different from the case of the finite difference method. However, For the simulated area, masses already delivered at the moment of earthquake are still left unaffected by the increase in the flow rate due to the earthquake.

Therefore, it is necessary to pay close attention to the case where the flow system changes abruptly or the mass changes in the medium due to a similar case to this example.

The embodiments and the accompanying drawings described in the present specification are merely illustrative of some of the technical ideas included in the present invention. Accordingly, the embodiments disclosed herein are for the purpose of describing rather than limiting the technical spirit of the present invention, and it is apparent that the scope of the technical idea of the present invention is not limited by these embodiments. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

1: Radioactive waste disposal system 10: Repository
100: a root-related area 200:
300: ecosystem z: capture zone

Claims (8)

A method for simulating the behavior of a radionuclide in a radioactive waste disposal system,
A division step of dividing the entire area of the radioactive waste disposal system into a numerical analysis area and a continuous analysis area;
A modeling step of modeling the behavior of the radionuclides in the numerical analysis area and the continuous analysis area, respectively, according to a possible outflow scenario; And
Calculating an amount of radionuclide movement between each of the regions divided in the dividing step by applying the modeling obtained in the modeling step;
A method for simulating radionuclide behaviors in a radioactive waste disposal system following an analysis zone partitioning. The method according to claim 1,
Between the modeling step and the calculating step,
A matching step of matching the results of modeling the behavior of the radionuclides in the numerical analysis region acquired in the modeling step and the results of modeling the radionuclides in the continuous analysis region;
A method for simulating radionuclide behaviors in a radioactive waste disposal system according to an analysis region partitioning. 3. The method of claim 2,
The matching step comprises:
And calculating the mass transfer rate of the radionuclide in the continuous analysis region. A method of simulating radionuclide behavior in a radioactive waste disposal system according to an analysis region partitioning. The method of claim 3,
The mass transfer rate of the radionuclide in the continuous analysis region may be,

A method for simulating radionuclide behaviors in a radioactive waste disposal system based on analytical domain segmentation, The method according to claim 1,
The radioactive waste disposal system includes a near-field region, a far field region, and an ecosystem,
Wherein the dividing step comprises:
Dividing the near-field region into one or more numerical analysis regions,
A method for simulating radionuclide behaviors in a radioactive waste disposal system according to an analytical domain segmentation that divides the scarce region and the ecosystem into one or more continuous analysis regions. The method according to claim 1,
The outflow scenario considered in the modeling step includes a well excavation scenario,
Wherein the dividing step comprises:
Wherein a capture zone is set as a capture zone in which the groundwater flowing into the excavated wells of the whole area of the radioactive waste disposal system flows and a capture zone is divided into a continuous analysis region, Method of simulating behavior. The method according to claim 1,
Wherein the outflow scenario considered in the modeling step comprises at least one of a colloidal scenario and a chelating agent scenario,
Wherein,
Method for simulating radionuclide behaviors in a radioactive waste disposal system according to an analytical domain split to calculate the amount of radionuclide migration taking into account the colloid scenario and the chelating agent scenario. The method according to claim 1,
Between the dividing step and the modeling step,
Wherein the step of dividing the numerical analysis region and the continuous analysis region further comprises the step of re-dividing the divided numerical analysis region and the continuous analysis region.

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