Leakage rate test method for reactor containment buildings

Abstract

The present invention provides a method for testing the leak rate of a reactor containment building, comprising: a partitioning step of separating the reactor containment building into an upper region and a lower region using an isolation device; a measurement step of measuring the leak rate of the containment building after pressurizing the inside of the containment building to a maximum pressure; and a determination step of determining whether the leak rate measured in the measurement step meets the leak rate acceptance criteria for the containment building.

Description

[Technical Field]

[0001] The present invention relates to a method for testing the leak rate of a nuclear reactor containment building. [Background technology]

[0002] The comprehensive leakage rate test for the containment building is a test to verify that the leakage rate of the containment building is within the allowable value for 24 hours under hypothetical conditions of a design basis accident (DBA) occurring in the containment building, thereby ensuring the airtightness of the containment building and confirming public safety.

[0003] Previously, to measure the containment building leakage rate of a nuclear power plant, a constant flow of instrument air was maintained inside the containment building for a certain period of time, and the increase or decrease in pressure in the containment building was calculated using the change in the containment building's volume to measure the containment building's leakage rate per hour.

[0004] Furthermore, the large amount of radioactive fluid must be completely drained and air must be pressurized to perform the leak test, resulting in the generation of a large amount of radioactive liquid waste, which requires high costs for waste disposal.

[0005] A large amount of radioactive fluid must be drained before the leak test, and then an additional water filling process must be performed after the leak test, which results in unnecessary long test times.

[0006] In this case, problems also arise in operation, such as operators and maintenance personnel being exposed to large amounts of radiation due to fluid drainage and filling. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide a method for testing the leak rate of a nuclear reactor containment building. [Means for solving the problem]

[0008] The object of the present invention is achieved by a method for testing the leak rate of a reactor containment building, comprising: a partitioning step of separating the reactor containment building into an upper region and a lower region using an isolation device; a measuring step of measuring the leak rate of the containment building after pressurizing the inside of the containment building to a maximum pressure; and a judging step of judging whether the leak rate measured in the measuring step satisfies the leak rate acceptance criteria for the containment building.

[0009] The measuring step includes a first measuring step of pressurizing the lower region with a first maximum pressure and then measuring a first leakage rate of the lower region; and a second measuring step of pressurizing the upper region with a second maximum pressure that is less than the first maximum pressure and then measuring a second leakage rate of the upper region.

[0010] The first maximum pressure and the second maximum pressure are set to 80% to 100% of the maximum pressure of a design basis accident of the containment building of the nuclear reactor.

[0011] The determination step includes a first determination step of determining whether the first leak rate satisfies a leak rate acceptance criterion for the lower region; and a second determination step of determining whether the second leak rate satisfies a leak rate acceptance criterion for the upper region.

[0012] The judgment step further includes a third judgment step of comparing the sum of the first leak rate and the second leak rate with the sum of the leak rate tolerance criteria for the lower region and the upper region to determine whether the leak rate tolerance criteria are met.

[0013] The method further includes a depressurization step of depressurizing the containment building to atmospheric pressure after the measurement step; and a recovery step of releasing the isolation device after the depressurization step.

[0014] The depressurization step includes a first depressurization step of depressurizing the lower region to atmospheric pressure after the first measurement step; and a second depressurization step of depressurizing the upper region to atmospheric pressure after the second measurement step.

[0015] The lower region contains a recharge water tank and the upper region contains a radioactive material removal tank.

[0016] The isolation device comprises:

[0017] It is installed in the radioactive material transfer piping that connects the recharge water tank and the radioactive material removal tank. [Effects of the Invention]

[0018] In accordance with the present invention, a method for testing the leak rate of a nuclear containment building is provided. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a flowchart showing a method for testing the leakage rate of a reactor containment building according to a first embodiment of the present invention. [Figure 2] 1 shows an upper area and a lower area of ​​a reactor containment building in a testing method according to a first embodiment of the present invention. [Figure 3] 1 is a flowchart showing in detail a measurement step, a depressurization step, and a judgment step in a method for testing the leak rate of a reactor containment building according to a first embodiment of the present invention. [Figure 4] 10 is a flowchart showing in detail a measurement step, a depressurization step, and a judgment step in a method for testing the leak rate of a reactor containment building according to a second embodiment of the present invention. [Figure 5] 10 is a flowchart showing a method for testing the leakage rate of a reactor containment building according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described in more detail below with reference to the accompanying drawings. The accompanying drawings are merely examples shown to more specifically explain the technical concept of the present invention, and the concept of the present invention is not limited to the accompanying drawings.

[0021] Although the following description will be given using SMART100 as an example, the reactor / containment building to which the present invention is applicable is not limited to this.

[0022] The method for testing the leakage rate of a reactor containment building will be described with reference to FIGS.

[0023] FIG. 1 is a flowchart showing a method for testing the leakage rate of a reactor containment building according to a first embodiment of the present invention, FIG. 2 shows the upper and lower regions of the reactor containment building in the testing method according to the first embodiment of the present invention, and FIG. 3 is a flowchart showing in detail the measurement step, depressurization step, and judgment step in the method for testing the leakage rate of a reactor containment building according to the first embodiment of the present invention.

[0024] The method for testing the leak rate of a reactor containment building according to this embodiment includes a compartmentalization step (S10), a measurement step (S20), a depressurization step (S30), a determination step (S40), and a restoration step (S50).

[0025] The decision step (S40) may be performed after or before the depressurization step (S30), and in another embodiment, may be performed after the restoration step (S50).

[0026] In the partitioning step (S10), the reactor containment building is separated into an upper region and a lower region using isolation devices.

[0027] The isolation device (Spectacle Flange) is located in the Radioactive Transfer Pipe (RTL) connecting the Recharge Water Tank (IRWST) and the Radioactive Removal Tank (RRT).

[0028] As shown in FIG. 2, the upper area (UCA, Upper Containment Area) includes the radioactive material removal tank (RRT), the upper pressurization system, and the upper data acquisition system (DAS).

[0029] The lower area (LCA, Lower Containment Area) includes the Recharge Water Tank (IRWST), the Lower Pressurization System, and the Lower Data Acquisition System (DAS).

[0030] In the measurement step (S20), the inside of the containment building is pressurized to the maximum pressure, and then the leakage rate of the containment building is measured.

[0031] Here, the maximum pressure refers to the maximum pressure (Pa) calculated under the hypothetical conditions of a design basis accident (DBA) occurring in the containment building.

[0032] In the case of the SMART100 containment building, the upper and lower regions are separated by water, and a pressure difference occurs between the upper and lower regions due to the difference in liquid head between the Radioactive Material Removal Tank (RRT) and the Recharge Water Tank (IRWST).

[0033] For example, the maximum pressure in the containment building in the upper region under the assumed conditions of a design basis accident is 0.1642 MPa (23.81 psi), while the maximum pressure in the lower region is 0.3142 MPa (45.57 psi), which are different from each other.

[0034] The measuring step (S20) includes a first measuring step (S21) and a second measuring step (S22).

[0035] In the first measuring step (S21), the lower region is pressurized with a first maximum pressure, and then a first leakage rate of the lower region is measured.

[0036] The first maximum pressure is set from the maximum pressure (Pa) of the containment building in the lower region under hypothetical conditions of a design basis accident.

[0037] For example, the first maximum pressure is between 0.25 MPa and 0.32 MPa, between 0.28 MPa and 0.32 MPa, or between 0.3140 MPa and 0.3142 MPa.

[0038] In the second measuring step (S22), the upper region is pressurized with a second maximum pressure, and then a second leakage rate of the upper region is measured.

[0039] The second maximum pressure is set from the maximum pressure (Pa) in the containment building in the upper region under hypothetical conditions of a design basis accident.

[0040] For example, the second maximum pressure is between 0.13 MPa and 0.17 MPa, between 0.16 MPa and 0.17 MPa, or between 0.1640 MPa and 0.1642 MPa.

[0041] The second maximum pressure is lower than the first maximum pressure, and the first maximum pressure and the second maximum pressure can be set to 80% to 100% or 90% to 100% of the design basis accident maximum pressure of the containment building of the reactor.

[0042] The detailed procedure of the measurement step (S20) will be described below with reference to FIG.

[0043] In the first embodiment shown in FIG. 3, a first measurement step (S21) and a second measurement step (S22) are carried out simultaneously.

[0044] However, in other embodiments, the first measurement step (S21) and the second measurement step (S22) may be performed in such a manner that the first measurement step (S21) is performed first, or the second measurement step (S22) is performed first.

[0045] In the depressurizing step (S30), the atmospheric pressure pressurized in the measuring step (S20) is reduced to atmospheric pressure.

[0046] The depressurization step (S30) includes a first depressurization step (S31) and a second depressurization step (S32).

[0047] As shown in FIG. 3, in the first depressurization step (S31), the lower region is depressurized to atmospheric pressure after the first measurement step (S21), and in the second depressurization step (S32), the upper region is depressurized to atmospheric pressure after the second measurement step (S22).

[0048] In other embodiments, the first depressurization step (S31) may be performed first, or the second depressurization step (S32) may be performed first, or the first depressurization step (S31) and the second depressurization step (S32) may be performed simultaneously.

[0049] In the decision step (S40), it is determined whether the leakage rate measured in the measurement step (S20) satisfies the leakage rate acceptance criteria of the containment building.

[0050] The determination step (S40) includes a first determination step (S41), a second determination step (S42), and a third determination step (S43).

[0051] In the first embodiment shown in FIG. 3, the first determination step (S41) and the second determination step (S42) are executed after the first pressure reduction step (S31) and the second pressure reduction step (S32).

[0052] In the first decision step (S41), it is determined whether the first leak rate satisfies the allowable leak rate (La[LCA]) criterion for the lower area.

[0053] The allowable leakage rate (La) is the limit value of the leakage rate of the reactor containment building at the standard test pressure, and is the value specified in the Operational Technical Guidelines.

[0054] If the first leakage rate is within a certain level compared to the allowable leakage rate standard for the lower region, it is determined that the lower region meets the allowable leakage rate standard, and if it exceeds the certain level, an operator is warned of leakage in the lower region.

[0055] The certain level can be selected, for example, from within 70% to 80% of the allowable leakage rate.

[0056] However, it is not limited to this, and in other embodiments, it can be selected from within 0.74 La [LCA] to 0.76 La [LCA].

[0057] In a second decision step (S42), it is determined whether the second leak rate satisfies the upper area allowable leak rate (La[UCA]) criterion.

[0058] If the second leakage rate is within a certain level compared to the allowable leakage rate standard for the upper region, it is determined that the upper region meets the allowable leakage rate standard, and if it exceeds the certain level, an operator is warned of leakage in the upper region.

[0059] Here, the certain level can be selected from, for example, 70% to 80%.

[0060] In other embodiments, it can be selected from within 0.74La[UCA] to 0.76La[UCA].

[0061] The second and third embodiments will be described below with reference to FIGS.

[0062] FIG. 4 is a flowchart showing in detail the measurement step, depressurization step, and judgment step in a method for testing the leak rate of a reactor containment building according to a second embodiment of the present invention, and FIG. 5 is a flowchart showing a method for testing the leak rate of a reactor containment building according to a third embodiment of the present invention.

[0063] In the second embodiment shown in FIG. 4, the first decision step (S41) and the second decision step (S42) are executed before the first pressure reduction step (S31) and the second pressure reduction step (S32).

[0064] In the third judgment step (S43), the sum of the first and second leakage rates is compared with the sum of the allowable leakage rate standard values ​​of the upper and lower regions (La[UCA+LCA]) to determine whether the allowable leakage rate standard is met.

[0065] If the sum of the first and second leakage rates is within a certain level compared to the allowable leakage rate standard for the upper and lower regions, it is determined that the leakage rate tolerance standard for the entire containment building is met, and if it exceeds the certain level, an alert is issued to the operator of a leakage in the containment building.

[0066] Again, the constant level can be selected from within 70% to 80%.

[0067] In other embodiments, it can be selected from within 0.74La[UCA+LCA] to 0.76La[UCA+LCA].

[0068] The third determination step (S43) will be described in detail with reference to FIG. 5 together with the pressure reduction step (S30) described later.

[0069] In the restoration step (S50), the isolation devices are released and the containment building pressure and radiation reduction system (CPRSS) is restored to its original state.

[0070] The restoration step (S50) is carried out after the depressurization step (S30) is performed.

[0071] In the third embodiment shown in FIG. 5, the restoration step (S50) is executed last after all steps, and the third determination step (S43) is executed before the restoration step (S50) is executed.

[0072] Although not shown, in another embodiment, the decision step (S40) including the third decision step (S43) can be performed after the recovery step (S50).

[0073] In addition, in the third embodiment, after the leakage rate measurement method in the lower region including the first judgment step (S41), the first measurement step (S21), the first judgment step (S41), and the first depressurization step (S31) is performed, the leakage rate measurement method in the upper region including the second measurement step (S22), the second judgment step (S42), and the second depressurization step (S32) is performed.

[0074] However, in other embodiments, the leak rate measurement method in the upper region may be performed before the leak rate measurement method in the lower region.

[0075] According to the present invention, a conservative comprehensive leak rate test of the SMART100 containment building can be performed without additional design changes, which reduces additional costs economically and meets the licensing requirements, making it possible to obtain standard design approval.

[0076] In addition, when testing each individual area, adjacent containment building areas are maintained at a pressure (atmospheric pressure) lower than the actual accident pressure, so more conservative results can be obtained in terms of leakage rate.

[0077] The method of the present invention can be used, particularly in the case of SMART100, when performing an Integrated Leak Rate Test of a nuclear containment building by injecting air only into the LCA (Lower Containment Area) using an air compressor.

[0078] The method of the present invention makes it possible to measure the amount of air leaking from an upper containment area (LCA) to a UCA due to the pressure difference between the LCA and the UCA.

[0079] It is also possible to measure the amount of air leaking from the LCA or UCA to the outside through the building.

[0080] Although certain parts of the present invention have been described in detail above, it is obvious to those skilled in the art that such specific descriptions are merely preferred embodiments and are not intended to limit the scope of the present invention. Therefore, the true scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for testing the leak rate of a SMART100 containment building, comprising: a compartmentalization step of separating the SMART100 containment building into an upper region and a lower region using an isolation device; a measuring step of measuring the leakage rate of the SMART100 containment building after pressurizing the interior of the SMART100 containment building to a maximum pressure; and determining whether the leak rate measured in the measuring step meets a leak rate acceptance criterion for the SMART100 containment building.

2. The measuring step a first measuring step of measuring a first leakage rate of the lower region after pressurizing the lower region with a first maximum pressure; and 2. The method of claim 1, further comprising a second measuring step of measuring a second leak rate of the upper region after pressurizing the upper region with a second maximum pressure less than the first maximum pressure.

3. The first maximum pressure and the second maximum pressure are 3. The method of claim 2, wherein the SMART100 containment structure is set at 80% to 100% of its maximum design basis accident pressure.

4. The determining step a first determining step of determining whether the first leak rate satisfies a leak rate acceptance criterion for the lower region; and 3. The method of claim 2, further comprising a second determining step of determining whether said second leak rate meets said upper region leak rate acceptance criteria.

5. The determining step 5. The method of claim 4, further comprising a third determination step of comparing the sum of the first leak rate and the second leak rate with the sum of the leak rate tolerance criteria for the lower region and the upper region to determine whether the leak rate tolerance criteria are met.

6. a depressurization step of depressurizing the SMART100 containment building to atmospheric pressure after the measurement step is performed; and 3. The method of claim 2, further comprising a recovery step of disengaging the isolation device after performing the depressurization step.

7. The decompression step includes: a first depressurization step of depressurizing the lower region to atmospheric pressure after the first measurement step; and 7. The method of claim 6, further comprising a second depressurization step of depressurizing the upper region to atmospheric pressure after the second measuring step.

8. the lower region includes a recharge water tank; The method of claim 1 , wherein the upper region comprises a radioactive material removal tank.

9. The isolation device comprises:

9. The method according to claim 8, wherein the method is installed in a radioactive material transfer pipe connecting the recharge water tank and the radioactive material removal tank.

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