TWI745047B - Management method of radioactive material storage container - Google Patents

Abstract

The present invention provides a method for managing a radioactive substance storage container capable of accurately estimating the gas temperature in a lid space and using it to accurately estimate the amount of air leakage in the lid space. The management method of the radioactive substance storage container 1 is to perform a gas filling operation of supplying gas to the lid space 6 in order to maintain the positive pressure state of the lid space 6. In this gas filling operation, the gas supply amount to the cover space 6 measured by the flow meter 15 and the gas pressure of the cover space 6 before and after the gas supply measured by the pressure gauge 11 are used to calculate the cover The gas temperature in the space 6 uses the gas temperature in the lid space 6 and the gas pressure in the lid space 6 before gas supply to calculate the gas mass in the lid space 6 before gas supply. In addition, the difference between the gas mass of the lid space 6 after the gas supply during the previous gas filling operation and the gas mass of the lid space 6 before the gas supply during the current gas filling operation is used to calculate the lid space 6 The air leakage.

Description

Management method of radioactive material storage container

The present invention relates to a method for managing a radioactive substance storage container with a primary cover and a secondary cover.

The fuel used in nuclear power plants contains highly radioactive materials, which generate decay heat. Therefore, cooling is carried out in the pool in the nuclear power plant within a certain period of time. After that, it is stored in a radioactive substance storage container and transported to a storage facility. And, keep it in a state of being stored in a radioactive substance storage container.

The radioactive material storage container has an internal space for storing used fuel (radioactive material), a primary cover covering the internal space, a secondary cover covering the primary cover, and a cover space formed between the primary cover and the secondary cover. The internal space and the cover space are sealed with metal gaskets or the like. However, it is necessary to consider the possibility that the sealing performance of the metal gasket will be reduced due to some reasons. Therefore, the inner space is filled with the inert gas so that it becomes a negative pressure state (in other words, the pressure is lower than the atmospheric pressure), and the cover space is filled with the inert gas so that it becomes a positive pressure state (in other words, the pressure is higher than the atmospheric pressure). This allows gas to leak from the cover space to the internal space, but prevents gas from leaking from the internal space to the cover space.

Patent Document 1 discloses a monitoring method of a radioactive substance storage container. In this monitoring method, the gas in the cover space is introduced into the pressure gauge through the hole and piping of the secondary cover, and the gas pressure in the cover space is measured by the pressure gauge.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2011-196715

Although it is not described in Patent Document 1, the amount of air leakage in the lid space can be estimated based on the decrease in the gas pressure in the lid space. However, under the influence of the external atmosphere, the gas temperature in the cover space changes, and consequently, the gas pressure in the cover space also changes. Therefore, it is difficult to accurately estimate the amount of air leakage in the cover space.

In order to solve the above problems, it is necessary to obtain the gas temperature in the lid space. Therefore, for example, consider the following method: adding a hole for introducing the gas in the lid space into the secondary lid of the thermometer, and measuring the gas temperature in the lid space with the thermometer. However, this method may increase the amount of air leakage in the cover space due to the increase of the holes of the secondary cover, so it is not good. As another method, for example, a method of measuring the temperature of the outer surface of the secondary cover with a thermometer instead of the gas temperature in the cover space is considered. However, in this method, if the followability of the outer surface temperature of the secondary cover to the gas temperature in the cover space is poor, the accuracy of the gas temperature in the cover space is reduced.

The present invention was made in view of the above circumstances, and its object is to provide a method for managing a radioactive substance storage container capable of accurately estimating the gas temperature in the lid space and using it to accurately estimate the amount of air leakage in the lid space.

In order to achieve the above object, the present invention is a management method of a radioactive material storage container, which has an internal space for storing radioactive materials, a primary cover covering the internal space, a secondary cover covering the primary cover, and a secondary cover formed on the primary cover The radioactive substance storage container in the lid space between the secondary lid and the secondary lid is targeted. In order to maintain the positive pressure state of the lid space, the gas filling operation of supplying gas to the lid space is performed; in this gas filling operation Calculate the gas temperature in the cover space using the gas supply amount to the cover space measured by the flowmeter and the gas pressure in the cover space before and after the gas supply measured by the pressure gauge. Use the cover The gas temperature of the space and the gas pressure of the cover space before the gas supply, or the gas temperature of the cover space, the gas pressure of the cover space after the gas supply, and the gas supply amount to the cover space are used to calculate The gas content of the cover space before gas supply is the difference between the gas content of the cover space after the gas supply during the previous gas filling operation and the above cover space before the gas supply during the current gas filling operation For the difference in gas substance quality, the amount of air leakage in the cover space between the time of the previous gas filling operation and the time of this gas filling operation is calculated.

According to the present invention, the gas temperature in the lid space can be accurately estimated, and the amount of air leakage in the lid space can be estimated with high accuracy.

1: Radioactive material storage container

2: main body

3: Internal space

4: cover once

5: Secondary cover

6: Cover space

7: Basket

8A: Metal gasket

8B: Metal gasket

9: Hole

10: Piping

11: Pressure gauge

12: Gate valve

13: Gas filling device

14: Gas supply device

15: Flowmeter

Fig. 1 is a partially broken perspective view showing the structure of the radioactive substance storage container in the first embodiment of the present invention.

Fig. 2 is a diagram showing the lid space of the radioactive substance storage container and related equipment in the first embodiment of the present invention.

Fig. 3 is a flow chart showing the outline of the management method of the radioactive substance storage container in the first embodiment of the present invention.

4 is a flowchart showing the outline of the first gas filling operation in the first embodiment of the present invention.

Fig. 5 is a flowchart showing the outline of each gas filling operation after the second time in the first embodiment of the present invention.

Fig. 6 is a flow chart showing the outline of the management method of the radioactive substance storage container in the second embodiment of the present invention.

Fig. 7 is a flowchart showing the outline of the method of managing the radioactive substance storage container in the third embodiment of the present invention.

The first embodiment of the present invention will be described with reference to the drawings.

Fig. 1 is a partially broken perspective view showing the structure of the radioactive substance storage container in this embodiment. Fig. 2 is a diagram showing the lid space of the radioactive substance storage container and related equipment in this embodiment.

The radioactive substance storage container 1 of this embodiment has: a bottomed cylindrical main body 2; an internal space 3 formed on the inside of the main body 2 to accommodate a plurality of used fuels (radioactive substances) not shown; a primary cover 4 , Which is installed in the opening of the main body 2 to cover the internal space 3; a secondary cover 5, which is installed in the opening of the main body 2 to cover the primary cover 4; and the cover space 6, which is formed in the primary cover 4 and the secondary cover Between 5. A basket 7 is provided in the internal space 3. The basket 7 forms a plurality of blocks respectively storing a plurality of used fuels.

An annular metal gasket 8A is provided between the primary cover 4 and the main body 2, and an annular metal gasket 8B is provided between the secondary cover 5 and the main body 2. Thereby, the internal space 3 and the cover space 6 are sealed. However, it is necessary to consider the possibility that the sealing performance of the metal gaskets 8A, 8B may be reduced due to some reasons. Therefore, the inner space 3 is filled with an inert gas (specifically, helium gas) so as to become a negative pressure state (in other words, a state where the pressure is lower than atmospheric pressure), and the cover space 6 becomes a positive pressure state (in other words, a pressure higher than Atmospheric pressure state) filled with inert gas. This allows gas to leak from the cover space 6 to the internal space 3, but prevents the gas from leaking from the internal space 3 to the cover space 6.

The radioactive substance storage container 1 of this embodiment further has a pipe 10 connected to the hole 9 of the secondary cover 5, and a pressure gauge 11 and a gate valve 12 connected to the pipe 10. The pressure gauge 11 introduces the gas in the cover space 6 through the hole 9 of the secondary cover 5 and the pipe 10, and measures the pressure. In this way, the operator can monitor the gas pressure in the cover space 6.

When the gas pressure in the cover space 6 measured by the pressure gauge 11 drops, the operator will The body filling device 13 is connected to the gate valve 12. The gas filling device 13 has a gas supply device 14 for supplying gas to the lid space 6, and a gas supply device 14 that measures the amount of gas supplied to the lid space 6 from the gas supply device 14 (corresponding to the amount of gas in this embodiment) Flowmeter 15. In order to maintain the positive pressure state of the lid space 6, the operator performs a gas filling operation of supplying gas from the gas supply device 14 to the lid space 6.

As a feature of this embodiment, the operator (or a computer) uses the gas supply amount to the cover space 6 measured by the flow meter 15 and the gas supply amount measured by the pressure gauge 11 during the gas filling operation. And the gas pressure in the lid space 6 after the gas is supplied to calculate the gas temperature in the lid space 6. In addition, the gas temperature in the lid space 6 and the gas pressure in the lid space 6 before the gas supply are used to calculate the amount of gas in the lid space 6 before the gas supply. In addition, the gas content of the cover space 6 after the gas supply during the previous gas filling operation (details are described below) and the gas content of the cover space 6 before the gas supply during the current gas filling operation The difference is calculated by calculating the amount of air leakage in the inner lid space 6 between the time of the previous gas filling operation and the time of this gas filling operation. In this way, the operator can monitor the amount of air leakage in the cover space 6.

Next, the management method of the radioactive substance storage container of the present embodiment having the above-mentioned characteristics will be explained. Fig. 3 is a flowchart showing the outline of the management method of the radioactive substance storage container in this embodiment. FIG. 4 is a flowchart showing the outline of the first gas filling operation in this embodiment. FIG. 5 is a flowchart showing the outline of each gas filling operation after the second time in this embodiment. Furthermore, "i" in the figure indicates the number of gas filling operations for supplying gas to the lid space 6 of the radioactive substance storage container 1.

The operator puts the radioactive substance storage container 1 into the pool in the nuclear power plant, stores a plurality of used fuels in the internal space 3 of the radioactive substance storage container 1, and installs a primary cover 4 on the opening of the radioactive substance storage container 1. Thereafter, the radioactive substance storage container 1 is taken out from the pool in the nuclear power plant, and the internal space 3 of the radioactive substance storage container 1 is vacuum dried by a vacuum drying device (not shown). Thereafter, so that the gas pressure in the internal space 3 becomes a negative pressure (for example, 0.08 MPa in detail), the gas is supplied from the gas filling device 13 to the internal space 3 through the hole and piping of the primary cover 4 (not shown) . Thereafter, the piping and the gas filling device 13 are removed from the hole of the primary cover 4, and the hole of the primary cover 4 is blocked.

Then, the operator installs the secondary cover 5 on the opening of the radioactive substance storage container 1, and vacuum-drys the lid space 6 of the radioactive substance storage container 1 with a vacuum drying device. Thereafter, as shown in step S100 in FIG. 3, the first gas filling operation is performed. In the first gas filling operation, gas is supplied from the gas filling device 13 to the cover space 6 through the hole 9 of the secondary cover 5 and the pipe 10 until the gas pressure in the cover space 6 reaches the upper limit (in detail , For example, 0.4 MPa) (refer to step S101 in FIG. 4). _{In addition, the gas supply amount ΔN 1} to the lid space 6 is measured by the flow meter 15 _{and is used as the gas substance amount N 1_B} of the lid space 6 after the gas is supplied, and is recorded together with the time t _{1_B} (refer to FIG. 4的Step S102).

Then, the operator transports the radioactive substance storage container 1 to the storage facility and keeps it in the storage facility. During the storage of the radioactive substance storage container 1, the operator monitors the gas pressure in the lid space 6 with the pressure gauge 11. That is, the process proceeds to step S104 through step S103 in FIG. 3, and it is determined whether or not the gas pressure of the cover space 6 measured by the pressure gauge 11 has dropped to the lower limit (for example, 0.3 MPa in detail). If the gas pressure in the cover space 6 measured by the pressure gauge 11 exceeds the lower limit, After a specified time, the determination of step S104 is repeated. On the other hand, if the gas pressure of the lid space 6 measured by the pressure gauge 11 is below the lower limit, the process proceeds to step S105, and the second gas filling operation is performed.

In the second gas filling operation, the operator uses the pressure gauge 11 to measure the gas pressure P _{2_A} of the cover space 6 before gas supply, and records it together with the time t _{2_A} (refer to step S106 in FIG. 5 ). Thereafter, gas is supplied from the gas filling device 13 to the lid space 6 through the hole 9 of the secondary lid 5 and the pipe 10 until the gas pressure of the lid space 6 reaches the upper limit (refer to step S107 in FIG. 5). _{In addition, the gas supply amount ΔN 2} to the cover space 6 is measured by the flowmeter 15, and the gas pressure P 2_B of the cover space 6 after the gas supply is measured by the pressure gauge 11 _{, and the value is} recorded together with the time t 2_B (Refer to steps S108 and S109 in Figure 5).

_{After that, the operator uses the gas supply amount ΔN 2} to the lid space 6 in the second gas filling operation, the gas pressure P 2_A of the lid space 6 before gas supply, and the gas of the lid space 6 after gas supply The pressure P _{2_B is calculated, and the gas temperature T 2 of the} lid space 6 is calculated and recorded (refer to step S110 in FIG. 5). To describe in detail, it is assumed that the gas temperature in the cover space 6 does not change before and after the gas is supplied. The reason is that the gas supplied from the gas filling device 13 to the lid space 6 has less substance than the remaining gas in the lid space 6, and has a very high heat capacity compared to the metal primary cover 4 and the secondary cover 5. For the sake of small. Based on the above assumptions, the gas state equation is deformed to derive the following equation (1) (where i=2, 3,...). V in the formula is the volume of the lid space 6 and is calculated in advance based on, for example, the design size or the measured size of the radioactive substance storage container 1. In the formula, R is the gas constant.

T _i =(P _{i_B} -P _{i_A} )×V/(△N _i ×R)…(1)

Of the above formula (1) into the gas supply amount to the lid portion space 6 of △ N _2, the lid portion space behind the cover portion the space in front of the gas supplied to the gas pressure of 6 of _P 2_A and a gas supply gas pressure of 6 of _P 2_B, calculated lid The gas temperature T _{2 in the} space 6 and record it.

After that, the operator substitutes the gas temperature T _{2 in} the lid space 6 and the gas pressure P _{2_A in the lid space 6 before gas supply into the gas state equation to calculate the gas mass N 2_A in} the lid space 6 before gas supply. And it is associated with the above-mentioned time t _{2_A} and recorded (refer to step S111 in FIG. 5). Further, the front cover portion of the gas supply space gas was 6 the mass of _N 2_A and △ N and ₂ of the gas supply amount of the cap portion of space 6, the calculated mass of the lid portion space behind the gas supplying the gas was 6 of _N 2_B, and It is associated with the above-mentioned time t _{2_B} and recorded (refer to step S112 in FIG. 5).

Thereafter, as shown in step S113 of FIG. 3, the operator changes from the gas content N _{1_B in} the cover space 6 after the gas supply during the first gas filling operation and before the gas supply during the second gas filling operation The difference in the amount of gas N _{2_A in the lid space 6 calculates the amount of air leakage Q 2} in the lid space 6 between the time of the first gas filling operation and the second time of gas filling operation. In this way, the operator can monitor the amount of air leakage in the cover space 6.

After that, it goes through step S114 in FIG. 3 and proceeds to the determination of step S104. When the gas pressure in the cover space 6 measured by the pressure gauge 11 exceeds the lower limit, after a specific time has elapsed, the determination in step S104 is repeated. On the other hand, when the gas pressure of the lid space 6 measured by the pressure gauge 11 is below the lower limit, the process proceeds to step S105, and the third gas filling operation is performed.

In the third gas filling operation, the operator uses the pressure gauge 11 to measure the gas pressure P _{3_A} of the cover space 6 before gas supply, and records it together with the time t _{3_A} (refer to step S106 in FIG. 5 ). Thereafter, gas is supplied from the gas filling device 13 to the lid space 6 through the hole 9 of the secondary lid 5 and the pipe 10 until the gas pressure in the lid space 6 reaches the upper limit (refer to step S107 in FIG. 5). _{In addition, the gas supply amount ΔN 3} to the cover space 6 is measured by the flow meter 15, and the gas pressure P 3_B of the cover space 6 after the gas supply is measured by the pressure gauge 11, and these are equal to the time t _{3_B} And record (refer to steps S108 and S109 in Figure 5).

_{Thereafter, the operator uses the gas supply amount ΔN 3} to the lid space 6 in the third gas filling operation, the gas pressure P 3_A of the lid space 6 before gas supply, and the gas pressure P 3_A of the lid space 6 after gas supply. The gas pressure P _{3_B is calculated, and the gas temperature T 3 of the} lid space 6 is calculated and recorded (refer to step S110 in FIG. 5 ). Then, using the gas temperature T ₃ of the lid space 6 and the gas pressure P _{3_A} of the lid space 6 before the gas supply, calculate the gas substance N _{3_A} of the lid space 6 before the gas supply, and compare it with the above time t _{3_A} is recorded in association (refer to step S111 in FIG. 5). And, with the front cover of the gas space 6 of the gas supply of substance and △ _N 3_A gas supply amount to cover the space section 6 and the sum of N _3, the gas supply of substance after calculating the lid portion 6 of the gas space _N 3_B, And it is recorded in association with the above-mentioned time t _{3_B} (refer to step S112 in FIG. 5 ).

Thereafter, as shown in step S113 of FIG. 3, the operator _{uses the gas content N 2_B in} the cover space 6 after the gas supply during the second gas filling operation and before the gas supply during the third gas filling operation The difference of the gas content N _{3_A of the lid space 6 is calculated to calculate the air leakage amount Q 3 of the} inner lid space 6 between the second gas filling operation and the third gas filling operation. In this way, the operator can monitor the amount of air leakage in the cover space 6. Then proceed with the same procedure as above.

As described above, in the present embodiment, in the gas filling operation, the gas supply amount to the cover space 6 measured by the flow meter 15 and the cover before and after the gas supply measured by the pressure gauge 11 are used. The gas pressure in the space 6 is calculated, and the gas temperature in the cover space 6 is calculated. Thereby, compared with the case where the outer surface temperature of the secondary cover 5 is measured by the temperature system instead of the gas temperature of the cover space 6, the gas temperature of the cover space 6 can be estimated with high accuracy. Moreover, compared with the case where the gas in the cover space 6 is introduced into the hole of the secondary cover 5 of the thermometer in order to measure the gas temperature in the cover space 6 with a thermometer, the amount of air leakage in the cover space 6 can be suppressed.

Furthermore, in this embodiment, during the gas filling operation, the gas temperature in the lid space 6 and the gas pressure in the lid space 6 before gas supply are used to calculate the gas mass in the lid space 6 before gas supply. In addition, the previous gas is calculated by the difference between the gas mass of the lid space 6 after the gas supply during the previous gas filling operation and the gas mass of the lid space 6 before the gas supply during the current gas filling operation The amount of air leakage in the inner lid space 6 between the time of the filling operation and the time of the current gas filling operation. Therefore, the amount of air leakage in the cover space 6 can be accurately estimated.

The second embodiment of the present invention will be described with reference to FIG. 6. Fig. 6 is a flowchart showing the outline of the management method of the radioactive substance storage container in this embodiment. In addition, in this embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description will be omitted as appropriate.

In the present embodiment, in the step S113 of FIG. 6, after calculating the space within the cap portion between the period when the current and previous gas filling operation when the amount of leakage gas filling work of 6 Q _i, proceeds to step S115. _{In step S115, the air leakage amount Q i} of the cover space 6 calculated in step S113 is assumed to be the gas increase amount △ in the internal space 3 between the time of the previous gas filling operation and the time of this gas filling operation M _{i , calculate the gas pressure P i_C} of the internal space 3 during this gas filling operation.

_{The method of calculating the gas pressure P 2_C} of the internal space 3 during the second gas filling operation will be specifically described. The operator puts the radioactive substance storage container 1 into the pool in the nuclear power plant, stores a plurality of used fuels in the internal space 3 of the radioactive substance storage container 1, and installs a primary cover 4 on the opening of the radioactive substance storage container 1. Thereafter, the radioactive substance storage container 1 is taken out from the pool in the nuclear power plant, and the internal space 3 of the radioactive substance storage container 1 is vacuum dried by a vacuum drying device (not shown). After that, the gas pressure of the internal space 3 becomes negative pressure (for example, 0.08 MPa in detail), and the gas filling device 13 with the flow meter 15 shown in FIG. 2 is connected to the hole and the primary cover 4 The piping (not shown) supplies gas from the gas filling device 13 to the internal space 3. At this time, the flow meter 15 measures the amount of gas supplied to the internal space 3 when the internal space 3 is filled with gas, and records it as the gas mass M ₁ of the internal space 3 during the first gas filling operation. The gas mass M ₁ of the internal space 3 is added to the gas increase ΔM ₂ (=Q _{2 ) of the internal space 3, and the gas mass M 2} of the internal space 3 during the second gas filling operation is calculated and recorded. Furthermore, the gas temperature of the internal space 3 is estimated based on, for example, the calorific value of the used fuel contained in the internal space 3, and the volume of the internal space 3 is calculated based on, for example, the design size or the measured size of the radioactive substance storage container 1. _{In addition, the gas mass M 2 of} the internal space 3 and the like are substituted into the gas state equation to _{calculate the gas pressure P 2_C} of the internal space 3 during the second gas filling operation.

_{The method of calculating the gas pressure P 3_C} of the internal space 3 during the third gas filling operation will be described. Add the gas mass M ₂ of the internal space 3 to the gas increase △M ₃ (=Q ₃ ) of the internal space 3 to calculate and record _{the gas mass M 3} of the internal space 3 during the third gas filling operation. _{Then, the gas mass M 3 of} the internal space 3 is substituted into the gas state equation to _{calculate the gas pressure P 3_C} of the internal space 3 during the third gas filling operation.

In this embodiment, the operator can determine whether the negative pressure state of the internal space 3 is maintained.

Furthermore, in the second embodiment, the following case is taken as an example for description: the gas mass _{Mi_1} in the internal space 3 during the previous gas filling operation is added to the gas increase _{ΔM i in the} internal space 3 to calculate The gas mass M _i of the internal space 3 during this gas filling operation is used to calculate the gas pressure P _{i_C} of the internal space 3 during this gas filling operation; Change within the scope of the subject. For example, the gas increase △M _{i of the} internal space 3 can also be used to calculate the gas pressure P _{i_C} of the internal space 3 during the current gas filling operation and the gas pressure P _{i-1_C of the internal space 3 during the previous gas filling operation} After the difference (P _{i_C} -P _{i-1_C} ), the gas pressure P _{i_C in the} internal space 3 is calculated.

_{The method of calculating the gas pressure P 2_C} of the internal space 3 during the second gas filling operation will be specifically described. _{Substituting the gas increase amount △M 2} of the internal space 3 with the formula (1) approximately the same as above, calculate the gas pressure P 2_C of the internal space 3 during the second gas filling operation and the difference between the gas pressure P _{2_C during} the first gas filling operation The difference between the gas pressure P _{1_C of the internal space 3 (P 2_C-} P _{1_C} ). The gas pressure P _{1_C of the} internal space 3 is, for example, set to the upper limit of the gas pressure of the internal space 3 when the internal space 3 is filled with gas, and this is added to the above difference to calculate and record _{the gas pressure P 2_C of the internal space 3.}

_{The method of calculating the gas pressure P 3_C} of the internal space 3 during the third gas filling operation will be described. _{Substitute the gas increase amount △M 3} of the internal space 3 into the equation roughly the same as the above formula (1), etc., calculate the gas pressure P 3_C of the internal space 3 during the third gas filling operation and the difference between the gas pressure P _{3_C during} the second gas filling operation The difference between the gas pressure P _{2_C of the internal space 3 (P 3_C-} P _{2_C} ). Add the gas pressure P _{2_C of the} internal space to the above difference to calculate the gas pressure P _{3_C of the} internal space 3 and record it.

In this modified example, the same effect as in the second embodiment can also be obtained.

The third embodiment of the present invention will be described with reference to FIG. 7. FIG. 7 is a flowchart showing the outline of the management method of the radioactive substance storage container in this embodiment. In addition, in this embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description will be omitted as appropriate.

In the present embodiment, in the step S113 of FIG. 7, the lid portion calculating the time period between the current and the previous gas filling operation when the amount of leakage gas filling the working space 6 of the _{Q i (= N i-1_B} - After N _{i_A} ), proceed to step S116. In step S116, the time _(t i_A -t _{i-1_B)} between the current time and the operating time of the gas filling the gas filling operation times before the cover portion of the space is calculated in step S113 in addition to the amount of leakage of 6 Q _i, is calculated lid The air leakage rate S _i of the space 6. Specifically, for example, between the time when the 2nd and the gas filling operation when the 1st to the gas filling operation _(t 2_A -t 1_B) except the time when the gas filling the 1st and the 2nd working gas filling operation _{The air leakage rate Q 2} of the cover space 6 during the period of time, and the air leakage rate S _{2 of the} cover space 6 is calculated. Also, for example, divide the time between the second gas filling operation and the third gas filling operation (t _{3_A} -t _{2_B} ) by the time between the second gas filling operation and the third gas filling operation During the period, the air leakage rate Q ₃ of the cover space 6 is calculated, and the air leakage rate S _{3 of the} cover space 6 is calculated.

In the present embodiment, the determination by the operator can cover the space portion 6 of the gas leakage rate is less than a predetermined value S _i, the metal gasket evaluated. 8A, 8B of the sealing performance is sufficient.

Furthermore, in the second embodiment, in step S115 in FIG. 6, the case of calculating the gas pressure P _{i_C} of the internal space 3 is taken as an example for description. In the third embodiment, in step S116 in FIG. 7, calculating the space in the lid portion 6 of the leakage rate of S _i of the case as an example, but is not limited to this, also be carried out step S115, the two S116.

Also, in the first to third embodiments, the following case is taken as an example for description: using the gas temperature T _i of the lid space 6 and the gas pressure P _{i_A} of the lid space 6 before gas supply to calculate the pre-gas supply The gas mass _{Ni_A} of the lid space 6 is _calculated from the sum of the gas mass Ni_A of the lid space 6 before gas supply and the gas supply amount △N _i to the lid space 6 to calculate the lid after gas supply The gas content _{Ni_B in the} space 6 is not limited to this, and can be changed without departing from the scope of the present invention. For example, the cover portion may also be used the gas space 6 of the temperature T _i and the cover portion of the gas supply space 6 of the gas pressure _P i_B, the lid portion of the gas supplied to the space after the gas was calculated from the mass of _N i_B 6. In addition, _{the difference between the amount of gas Ni_B} in the lid space 6 after gas supply and the amount of gas _{ΔN i} supplied to the lid space 6 (in other words, use the gas temperature T _{i of the lid space 6 and the gas} The gas pressure _{Pi_B} of the lid space 6 and the gas supply amount to the lid space 6 _{ΔN i ), and the gas mass Ni_A} of the lid space 6 before gas supply is calculated.

In addition, in the first to third embodiments, a case where the volume V of the lid space 6 is calculated by using the design size or the measured size of the radioactive substance storage container 1 is taken as an example for description, but it is not limited to this, and may not be Changes are made within the scope deviating from the gist of the present invention. For example, when the used fuel is not contained in the internal space 3 of the radioactive substance storage container 1, gas may be supplied to the lid space 6, and the volume V of the lid space 6 can be calculated using the value measured at this time. In detail, since it is in a state where the internal space 3 of the radioactive substance storage container 1 does not contain used fuel, it is considered that the gas temperature in the lid space 6 is the same as the temperature of the outer surface of the secondary lid 5. The temperature of the outer surface of the secondary cover 5 is measured. In addition, the gas temperature of the lid space 6, the gas supply amount to the lid space 6 measured by the flow meter 15, and the lid space 6 before and after the gas supply measured by the pressure gauge 11 can also be used. Calculate the volume V of the lid space 6 (refer to the above equation (1)).

1: Radioactive material storage container

2: main body

3: Internal space

4: cover once

5: Secondary cover

6: Cover space

8A: Metal gasket

8B: Metal gasket

9: Hole

10: Piping

11: Pressure gauge

12: Gate valve

13: Gas filling device

14: Gas supply device

15: Flowmeter

Claims (4)

A management method for a radioactive material storage container, characterized in that it has an internal space for storing radioactive materials, a primary cover covering the internal space, a secondary cover covering the primary cover, and a secondary cover formed on the primary cover and the secondary cover. The radioactive substance storage container in the lid space between the secondary lids is the object, in order to maintain the positive pressure state of the lid space, and perform the gas filling operation of supplying gas to the lid space; and during this gas filling operation , Use the gas supply amount to the cover space measured by the flowmeter and the gas pressure of the cover space before and after the gas supply measured by the pressure gauge to calculate the gas temperature of the cover space, use the cover space The gas temperature and the gas pressure in the lid space before the gas supply, or the gas temperature in the lid space, the gas pressure in the lid space after the gas supply, and the gas supply amount to the lid space, are used to calculate the gas The amount of gas in the cover space before the supply is used in the previous gas filling operation. The gas supply amount to the cover space measured by the flow meter and the gas measured by the pressure gauge during the gas filling operation are used in the same way as this time. The gas pressure in the lid space before and after the gas supply is calculated, and the gas temperature in the lid space is calculated using the gas temperature in the lid space, the gas pressure in the lid space before the gas supply, and to the lid space The amount of gas supplied, or the gas temperature in the lid space and the gas pressure in the lid space after gas supply are used to calculate the amount of gas in the lid space after the gas is supplied, and the gas from the previous gas filling operation The difference between the gas content of the cover space after the supply and the gas content of the cover space before the gas supply during this gas filling operation, Calculate the amount of air leakage in the cover space between the time of the previous gas filling operation and the time of the current gas filling operation. For example, the method for managing a radioactive substance storage container in claim 1, wherein the first gas filling operation changes the lid space from a vacuum state to filling the lid space with gas, and after the gas supply in the first gas filling operation The amount of gas in the cover space is the amount of gas supplied to the cover space measured by the flowmeter during the first gas filling operation, and the cover space after the gas supply during the second and subsequent gas filling operations The gas mass is the gas mass of the lid space and the gas supply amount to the lid space before gas supply during each gas filling operation, or the gas temperature of the lid space during each gas filling operation Calculated with the gas pressure in the lid space after gas supply. For example, the method for managing a radioactive substance storage container of claim 1, wherein after storing radioactive substances in the internal space and installing the primary cover, when the internal space is changed from a vacuum state to filling the internal space with gas, the measurement is made to the inside The gas supply amount of the space, or the pressure after filling the gas into the internal space, and the gas temperature of the internal space estimated from the volume of the internal space and the calorific value of the radioactive material are used to calculate the initial gas mass of the internal space Calculate the gas pressure of the internal space from the sum of the initial gas content of the internal space and the increase of the gas by assuming the air leakage of the cover space as the increase of the gas in the internal space. For example, the method for managing radioactive substance storage containers in claim 1, where the time between the previous gas filling operation and the current gas filling operation is divided by the amount of air leakage in the lid space, and the air leakage rate in the lid space is calculated .

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