JP7096802B2 - How to manage radioactive material storage containers - Google Patents

Description

The present invention relates to a method for managing a radioactive material storage container having a primary lid and a secondary lid.

The fuel used in nuclear power plants contains highly radioactive substances, and its decay heat is generated. Therefore, it is cooled in the pool inside the nuclear power plant for a certain period of time. After that, it is stored in a radioactive material storage container and transported to a storage facility. Then, it is stored 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 lid that covers the internal space, a secondary lid that covers the primary lid, and a lid formed between the primary lid and the secondary lid. It has a part space. The internal space and the lid space are sealed with a metal gasket or the like. However, it is necessary to consider the possibility that the sealing performance of the metal gasket may deteriorate for some reason. Therefore, the internal space is filled with an inert gas so as to be in a negative pressure state (in other words, a state lower than the atmospheric pressure), and the lid space is in a positive pressure state (in other words, a state higher than the atmospheric pressure). The inert gas is filled so as to be. This allows gas leakage from the lid space to the internal space, but prevents gas leakage from the internal space to the lid space.

Patent Document 1 discloses a method for monitoring a radioactive material storage container. In this monitoring method, the gas in the lid space is introduced into the pressure gauge through the holes and pipes in the secondary lid, and the gas pressure in the lid space is measured by the pressure gauge.

Japanese Unexamined Patent Publication No. 2011-196715

Although not described in Patent Document 1, it is possible to estimate the amount of gas leakage in the lid space from the decrease width of the gas pressure in the lid space. However, the gas temperature in the lid space changes due to the influence of the outside air and the like, and the gas pressure in the lid space also changes accordingly. Therefore, it is difficult to accurately estimate the amount of gas leakage in the lid space.

In order to solve the above-mentioned problems, it is necessary to acquire the gas temperature in the lid space. Therefore, for example, a method of adding a hole in the secondary lid for introducing the gas in the lid space into the thermometer and measuring the gas temperature in the lid space with the thermometer can be considered. However, this method is not preferable because the number of holes in the secondary lid may increase and the amount of gas leakage in the lid space may increase. As another method, for example, a method of measuring the outer surface temperature of the secondary lid with a thermometer can be considered as an alternative to the gas temperature of the lid space. However, in this method, if the outer surface temperature of the secondary lid does not follow the gas temperature of the lid space poorly, the accuracy of the gas temperature of the lid space deteriorates.

The present invention has been made in view of the above circumstances, and an object of the present invention is to accurately estimate the gas temperature in the lid space and to use this to accurately estimate the amount of gas leakage in the lid space. The purpose is to provide a method for managing a radioactive substance storage container.

In order to achieve the above object, the present invention has an internal space for accommodating a radioactive substance, a primary lid covering the internal space, a secondary lid covering the primary lid, and between the primary lid and the secondary lid. A radioactive substance storage container having a lid space formed in the above, and performing gas filling work to supply gas to the lid space in order to maintain a positive pressure state of the lid space. During the gas filling operation this time, the amount of gas supplied to the lid space measured by the flow meter and the gas in the lid space before and after the gas supply measured by the pressure gauge. The gas temperature in the lid space is calculated using the pressure, and the gas temperature in the lid space and the gas pressure in the lid space before the gas supply are used, or the gas temperature and gas in the lid space are used. Using the gas pressure in the lid space after supply and the gas supply amount to the lid space, the amount of gas substance in the lid space before gas supply is calculated, and after the gas supply in the previous gas filling operation. Due to the difference between the amount of gas material in the lid space and the amount of gas material in the lid space before gas supply during the current gas filling work, the period between the previous gas filling work and the current gas filling work The amount of gas leakage in the lid space is calculated.

According to the present invention, the gas temperature in the lid space can be estimated accurately, and the amount of gas leakage in the lid space can be estimated accurately using this.

It is a partially cutaway perspective view which shows the structure of the radioactive material storage container in 1st Embodiment of this invention. It is a figure which shows the related equipment together with the lid space of the radioactive material storage container in 1st Embodiment of this invention. It is a flowchart which shows the outline of the management method of the radioactive material storage container in 1st Embodiment of this invention. It is a flowchart which shows the outline of the 1st gas filling operation in 1st Embodiment of this invention. It is a flowchart which shows the outline of each gas filling operation after the 2nd time in 1st Embodiment of this invention. It is a flowchart which shows the outline of the management method of the radioactive material storage container in 2nd Embodiment of this invention. It is a flowchart which shows the outline of the management method of the radioactive material storage container in 3rd Embodiment of this 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 material storage container in the present embodiment. FIG. 2 is a diagram showing related equipment together with the lid space of the radioactive material storage container in the present embodiment.

The radioactive material storage container 1 of the present embodiment has a bottomed cylindrical body 2, an internal space 3 formed inside the body 2 and accommodating a plurality of used fuels (radioactive substances) (not shown), and the body 2. It was formed between the primary lid 4 attached to the opening and covering the internal space 3, the secondary lid 5 attached to the opening of the fuselage 2 and covering the primary lid 4, and the primary lid 4 and the secondary lid 5. It has a lid space 6. A basket 7 is provided in the internal space 3. The basket 7 forms a plurality of compartments for accommodating a plurality of spent fuels.

An annular metal gasket 8A is provided between the primary lid 4 and the body 2, and an annular metal gasket 8B is provided between the secondary lid 5 and the body 2. As a result, the internal space 3 and the lid space 6 are sealed. However, it is necessary to consider the possibility that the sealing performance of the metal gaskets 8A and 8B may deteriorate for some reason. Therefore, the internal space 3 is filled with an inert gas (specifically, for example, helium gas) so as to be in a negative pressure state (in other words, a state lower than the atmospheric pressure), and the lid space 6 is in a positive pressure state. (In other words, the inert gas is filled so as to be in a state where the pressure is higher than the atmospheric pressure). This allows gas leakage from the lid space 6 to the internal space 3, but prevents gas leakage from the internal space 3 to the lid space 6.

The radioactive material storage container 1 of the present embodiment further has a pipe 10 connected to the hole 9 of the secondary lid 5, a pressure gauge 11 connected to the pipe 10, and a sluice valve 12. The pressure gauge 11 introduces gas in the lid space 6 through the hole 9 of the secondary lid 5 and the pipe 10, and measures the pressure thereof. This allows the worker to monitor the gas pressure in the lid space 6.

When the gas pressure in the lid space 6 measured by the pressure gauge 11 drops, the worker connects the gas filling device 13 to the sluice valve 12. The gas filling device 13 has a gas supply device 14 that supplies gas to the lid space 6 and a gas supply amount (corresponding to the amount of gas substance in the present embodiment) supplied from the gas supply device 14 to the lid space 6. It has a flow meter 15 for measuring. In order to maintain the positive pressure state of the lid space 6, the worker performs a gas filling operation of supplying gas from the gas supply device 14 to the lid space 6.

As a feature of the present embodiment, the worker (or a computer may be used) performs the gas supply amount to the lid space 6 measured by the flow meter 15 and the gas supply before and as measured by the pressure gauge 11 during the gas filling operation. The gas temperature of the lid space 6 is calculated using the gas pressure of the lid space 6 after the gas is supplied. Then, the gas temperature of the lid space 6 and the gas pressure of the lid space 6 before the gas supply are used to calculate the amount of gas substance in the lid space 6 before the gas supply. Then, due to the difference between the amount of gas substance in the lid space 6 after gas supply at the time of the previous gas filling work (details will be described later) and the amount of gas substance in the lid space 6 before gas supply at the time of this gas filling work. , The amount of gas leakage in the lid space 6 during the period between the previous gas filling work and the current gas filling work is calculated. As a result, the worker can monitor the amount of gas leakage in the lid space 6.

Next, a method for managing the radioactive material storage container of the present embodiment having the above-mentioned characteristics will be described. FIG. 3 is a flowchart showing an outline of the management method of the radioactive material storage container in the present embodiment. FIG. 4 is a flowchart showing an outline of the first gas filling operation in the present embodiment. FIG. 5 is a flowchart showing an outline of each gas filling operation from the second time onward in the present embodiment. In addition, "i" in the figure indicates the number of times the gas filling operation for supplying gas to the lid space 6 of the radioactive material storage container 1 is performed.

The worker takes the radioactive material 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 material storage container 1, and puts the primary lid 4 in the opening of the radioactive material storage container 1. Install. After that, the radioactive material storage container 1 is taken out from the pool in the nuclear power plant, and the internal space 3 of the radioactive material storage container 1 is vacuum-dried by a vacuum drying device (not shown). After that, gas is supplied from the gas filling device 13 to the internal space 3 through a hole and a pipe of the primary lid 4 (not shown) so that the gas pressure in the internal space 3 becomes a negative pressure (specifically, for example, 0.08 MPa). do. After that, the pipe and the gas filling device 13 are removed from the hole of the primary lid 4 to close the hole of the primary lid 4.

Then, the worker attaches the secondary lid 5 to the opening of the radioactive material storage container 1, and vacuum-drys the lid space 6 of the radioactive material storage container 1 with a vacuum drying device. After that, as shown in step S100 of FIG. 3, the first gas filling operation is performed. In the first gas filling operation, from the gas filling device 13 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 value (specifically, for example, 0.4 MPa). Gas is supplied to the lid space 6 (see step S101 in FIG. 4). Further, the gas supply amount ΔN ₁ to the lid space 6 is measured by the flow meter 15, and recorded as the gas substance amount N _{1_B} in the lid space 6 after gas supply together with the time t _{1_B} (step S102 in FIG. 4). reference).

Then, the worker transports the radioactive material storage container 1 to the storage facility and stores it in the storage facility. During storage of the radioactive material storage container 1, the worker monitors the gas pressure in the lid space 6 with the pressure gauge 11. That is, the process proceeds to step S104 via step S103 in FIG. 3, and it is determined whether or not the gas pressure in the lid space 6 measured by the pressure gauge 11 has dropped to the lower limit value (specifically, for example, 0.3 MPa). When the gas pressure in the lid space 6 measured by the pressure gauge 11 exceeds the lower limit value, the determination in step S104 is repeated after a predetermined time has elapsed. On the other hand, when the gas pressure of the lid space 6 measured by the pressure gauge 11 is not more than the lower limit value, the process proceeds to step S105 to perform the second gas filling operation.

In the second gas filling operation, the worker measures the gas pressure P _{2_A} of the lid space 6 before the gas supply with the pressure gauge 11 and records it together with the time t _{2_A} (see step S106 in FIG. 5). After that, 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 (see step S107 in FIG. 5). ). Further, the gas supply amount ΔN ₂ to the lid space 6 is measured by the flow meter 15, the gas pressure P _{2_B} of the lid space 6 after gas supply is measured by the pressure gauge 11, and they are recorded together with the time t _{2_B} . (See steps S108 and S109 in FIG. 5).

After that, the worker changed the gas supply amount ΔN ₂ to the lid space 6 in the second gas filling operation, the gas pressure _{P2_A} of the lid space 6 before the gas supply, and the gas pressure of the lid space 6 after the gas supply. Using P _{2_B} , the gas temperature T ₂ of the lid space 6 is calculated and recorded (see step S110 in FIG. 5). More specifically, it is assumed that the gas temperature of the lid space 6 does not change before and after the gas supply. The reason is that the gas supplied from the gas filling device 13 to the lid space 6 has a smaller amount of substance than the gas remaining in the lid space 6, and has a heat capacity with respect to the metal primary lid 4 and the secondary lid 5. Is very small. Based on the above assumption, the equation of state of gas is transformed to derive the following equation (1) (however, 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 dimension or the measurement dimension of the radioactive material storage container 1. R in the equation is a gas constant.
T _i = (P _{i_B} -P _{i_A} ) x V / (ΔN _i x R) ... (1)

Substituting the gas supply amount ΔN ₂ to the lid space 6, the gas pressure P _{2_A} of the lid space 6 before the gas supply, and the gas pressure P _{2_B} of the lid space 6 after the gas supply to the above equation (1). Then, the gas temperature T2 of the lid space ₆ is calculated and recorded.

After that, the worker substitutes the gas temperature T2 of the lid space ₆ and the gas pressure P2_A of the lid space 6 before the gas supply into the gas state equation, and substitutes the gas pressure _{P2_A} of the lid space 6 before the gas supply. The gas substance amount N _{2_A} is calculated and recorded in association with the above-mentioned time t _{2_A} (see step S111 in FIG. 5). Further, the gas substance amount N _{2_B} of the lid space 6 after gas supply is calculated from the sum of the gas substance amount N _{2_A} of the lid space 6 before gas supply and the gas supply amount ΔN ₂ to the lid space 6. , And record it in association with the time t _{2_B} described above (see step S112 in FIG. 5).

After that, as shown in step S113 of FIG. 3, the worker has the gas substance amount _{N1_B} in the lid space 6 after the gas supply in the first gas filling work and before the gas supply in the second gas filling work. The gas leakage amount Q2 of the lid space 6 during the period between the first gas filling work and the _second gas filling work is calculated from the difference from the gas substance amount N _{2_A} of the lid space 6. As a result, the worker can monitor the amount of gas leakage in the lid space 6.

After that, the process proceeds to the determination in step S104 through step S114 in FIG. When the gas pressure in the lid space 6 measured by the pressure gauge 11 exceeds the lower limit value, the determination in step S104 is repeated after a predetermined time has elapsed. On the other hand, when the gas pressure of the lid space 6 measured by the pressure gauge 11 is not more than the lower limit value, the process proceeds to step S105 to perform the third gas filling operation.

In the third gas filling operation, the worker measures the gas pressure P _{3_A} of the lid space 6 before gas supply with the pressure gauge 11 and records it together with the time t _{3_A} (see step S106 in FIG. 5). After that, 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 (see step S107 in FIG. 5). ). Further, the gas supply amount ΔN ₃ to the lid space 6 is measured by the flow meter 15, the gas pressure P _{3_B} of the lid space 6 after gas supply is measured by the pressure gauge 11, and they are recorded together with the time t _{3_B} . (See steps S108 and S109 in FIG. 5).

After that, the worker changed the gas supply amount ΔN ₃ to the lid space 6 in the third gas filling operation, the gas pressure _{P3_A} of the lid space 6 before the gas supply, and the gas pressure of the lid space 6 after the gas supply. Using P _{3_B} , the gas temperature T ₃ of the lid space 6 is calculated and recorded (see step S110 in FIG. 5). After that, 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 are used to calculate the gas substance amount N _{3_A} of the lid space 6 before the gas supply, which is described above. It is recorded in association with the time t _{3_A} (see step S111 in FIG. 5). Further, the gas substance amount N _{3_B} of the lid space 6 after the gas supply is calculated from the sum of the gas substance amount N _{3_A} of the lid space 6 before the gas supply and the gas supply amount ΔN ₃ to the lid space 6. , And record it in association with the time _{t3_B} described above (see step S112 in FIG. 5).

After that, as shown in step S113 of FIG. 3, the worker has the amount of gas substance N _{2_B} in the lid space 6 after the gas supply in the second gas filling work and before the gas supply in the third gas filling work. The gas leakage amount Q3 of the lid space 6 during the period between the second gas filling work and the _third gas filling work is calculated from the difference from the gas substance amount N _{3_A} of the lid space 6. As a result, the worker can monitor the amount of gas leakage in the lid space 6. After that, the same procedure as described above is performed.

As described above, in the present embodiment, during the gas filling operation, the amount of gas supplied 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. The gas temperature of the lid space 6 is calculated using the gas pressure of. Thereby, the gas temperature of the lid space 6 can be estimated more accurately than the case where the outer surface temperature of the secondary lid 5 is measured by the temperature system as an alternative to the gas temperature of the lid space 6. Further, in order to measure the gas temperature of the lid space 6 with a thermometer, gas leakage of the lid space 6 is compared with the case of adding a hole of the secondary lid 5 for introducing the gas of the lid space 6 into the thermometer. The amount can be suppressed.

Further, in the present embodiment, during the gas filling operation, the gas temperature of the lid space 6 and the gas pressure of the lid space 6 before the gas supply are used to determine the amount of gas substance in the lid space 6 before the gas supply. calculate. Then, due to the difference between the amount of gas substance in the lid space 6 after the gas supply at the time of the previous gas filling work and the amount of the gas substance in the lid space 6 before the gas supply at the time of the current gas filling work, the previous gas filling is performed. The amount of gas leakage in the lid space 6 during the period between the work and the gas filling work this time is calculated. Therefore, the amount of gas leakage in the lid space 6 can be estimated accurately.

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

In the present embodiment, in step S113 of FIG. 6, the gas leakage amount _Qi of the lid space 6 during the period between the previous gas filling work and the current gas filling work is calculated, and then the process proceeds to step S115. In step S115, the gas leakage amount Qi of the lid space 6 calculated in step S113 is assumed as the gas increase amount _{ΔM i of} the internal space 3 during the period between the previous gas filling work and the current gas filling work. Then, the gas pressure _{Pi_C} of the internal space 3 at the time of the gas filling operation this time is calculated.

Specifically, a method of calculating the gas pressure _{P2_C} of the internal space 3 at the time of the second gas filling operation will be described. The worker takes the radioactive material 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 material storage container 1, and puts the primary lid 4 in the opening of the radioactive material storage container 1. Install. After that, the radioactive material storage container 1 is taken out from the pool in the nuclear power plant, and the internal space 3 of the radioactive material storage container 1 is vacuum-dried by a vacuum drying device (not shown). After that, the gas filling device 13 equipped with the flow meter 15 shown in FIG. 2 is provided with a hole in the primary lid 4 and a pipe (specifically, for example, 0.08 MPa) so that the gas pressure in the internal space 3 becomes a negative pressure (specifically, 0.08 MPa). (Not shown), and gas is supplied from the gas filling device 13 to the internal space 3. At this time, the amount of gas supplied to the internal space 3 when the internal space 3 is filled with gas is measured by the flow meter 15, and recorded as the amount of gas substance M ₁ in the internal space 3 during the first gas filling operation. The gas increase amount ΔM ₂ (= Q ₂ ) of the internal space 3 is added to the gas substance amount M ₁ of the internal space 3 to obtain the gas substance amount M ₂ of the internal space 3 at the time of the second gas filling operation. Calculate and record. The gas temperature of the internal space 3 is estimated based on, for example, the calorific value of the used fuel stored in the internal space 3, and the volume of the internal space 3 is, for example, the design dimension or the measurement dimension of the radioactive substance storage container 1. It is calculated based on. Then, by substituting the gas substance amount M ₂ of the internal space 3 described above into the gas state equation, the gas pressure P _{2_C} of the internal space 3 at the time of the second gas filling operation is calculated.

A method of calculating the gas pressure _{P3_C} of the internal space 3 at the time of the third gas filling operation will be described. Add the gas increase amount ΔM ₃ (= Q ₃ ) of the internal space 3 to the gas substance amount M ₂ of the internal space 3 to calculate the gas substance amount M ₃ of the internal space 3 at the time of the third gas filling operation. And record. Then, by substituting the gas substance amount M ₃ of the internal space 3 described above into the gas state equation, the gas pressure P _{3_C} of the internal space 3 at the time of the third gas filling operation is calculated.

In the present embodiment, the worker can determine whether or not the negative pressure state of the internal space 3 is maintained.

In the second embodiment, the gas increase amount _ΔMi in the internal space 3 is added to the gas substance amount Mi _-1 in the internal space 3 at the time of the previous gas filling work, and the gas filling operation this time is performed. The case where the gas substance amount Mi of the internal space 3 at the time is calculated and the gas pressure _{Pi_C} of the internal space 3 at the time of the current gas filling operation is calculated is described as an example, but the present _invention is not limited to this. Modification is possible within a range that does not deviate from the gist of the present invention. For example, using the gas increase amount _ΔMi of the internal space 3, the gas pressure _{Pi_C} of the internal space 3 at the time of the current gas filling work and the gas pressure Pi _{-1_C} of the internal space 3 at the time of the previous gas filling work After calculating the difference (P _{i_C} − P _{i-1_C} ), the gas pressure _{Pi_C} of the internal space 3 may be calculated.

Specifically, a method of calculating the gas pressure _{P2_C} of the internal space 3 at the time of the second gas filling operation will be described. Substituting the gas increase amount ΔM ₂ of the internal space 3 into the equation which is almost the same as the above equation (1), the gas pressure P _{2_C} of the internal space 3 at the time of the second gas filling operation and the first time. The difference (P _{2_C −} P _{1_C} ) from the gas pressure P _{1_C} of the internal space 3 at the time of gas filling work is calculated. The gas pressure P _{1_C} of the internal space 3 is, for example, the upper limit of the gas pressure of the internal space 3 when the gas of the internal space 3 is filled, and the gas pressure P _{2_C} of the internal space 3 is calculated by adding it to the above-mentioned difference. ,Record.

A method of calculating the gas pressure _{P3_C} of the internal space 3 at the time of the third gas filling operation will be described. Substituting the gas increase amount ΔM ₃ of the internal space 3 into the equation which is almost the same as the above equation (1), the gas pressure P _{3_C} of the internal space 3 at the time of the third gas filling operation and the second time. The difference (P _{3_C −} P _{2_C} ) from the gas pressure P _{2_C} of the internal space 3 at the time of gas filling work is calculated. The gas pressure P _{2_C} in the internal space is added to the above-mentioned difference to calculate and record the gas pressure P _{3_C} in the internal space 3.

Also in this modification, the same effect as that of the second embodiment can be obtained.

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

In the present embodiment, in step S113 of FIG. 7, the gas leakage amount Qi ( ₌ Ni _{-1_B} −N _{i_A} ) of the lid space 6 during the period between the previous gas filling work and the current gas filling work is determined. After the calculation, the process proceeds to step S116. In step S116, the gas leakage amount Qi of the lid space 6 calculated in step S113 is divided by the time ( _{ti_A -ti-1_B )} between the previous gas filling work and the current gas filling work. Then, the gas leakage rate _Si of the lid space 6 is calculated. Specifically, for example, the amount of gas leakage _Q2 in the lid space 6 during the period between the first gas filling operation and the second gas filling operation is determined by the first gas filling operation and the second gas filling operation. The gas leakage rate S2 of the lid space 6 is calculated by dividing by the time during work (t _{2_A − t 1_B} ). Further, for example, the gas leakage amount _Q3 of the lid space 6 during the period between the second gas filling work and the third gas filling work can be measured between the second gas filling work and the third gas filling work. The gas leakage rate S3 of the lid space ₆ is calculated by dividing by the time (t _{3_A −} t _{2_B} ).

In the present embodiment, the worker evaluates whether the sealing performance of the metal gaskets 8A and 8B is sufficient by determining whether the gas leakage rate _Si of the lid space 6 is lower than the specified value. Can be done.

In the second embodiment, the case where the gas pressure _{Pi_C} of the internal space 3 is calculated in step S115 of FIG. 6 is taken as an example, and in the third embodiment, in step S116 of FIG. The case of calculating the gas leakage rate S _i of the lid space 6 has been described as an example, but the present invention is not limited to this, and both steps S115 and S116 may be performed.

Further, in the first to third embodiments, the gas temperature _{Ti of the lid space 6 and the gas pressure Pi_A of} the lid space 6 before the gas supply are used to use the gas in the lid space 6 before the gas supply. The amount of gas N i_A is calculated, and the gas material in the lid space 6 after gas supply is calculated by _{adding the gas material amount N i_A in} the lid space 6 before gas supply and the gas supply amount ΔN _i to the lid space 6. The case of calculating the quantity _{Ni_B} has been described as an example, but the present invention is not limited to this, and modifications can be made within a range that does not deviate from the gist of the present invention. For example, the gas temperature _{Ti of the lid space 6 and the gas pressure Pi_B of} the lid space 6 after the gas supply may be used to calculate the gas substance amount _{Ni_B} of the lid space 6 after the gas supply. Further, due to the difference between the amount of gas substance N _{i_B} in the lid space 6 after gas supply and the gas supply amount ΔN _i in the lid space 6 (in other words, the gas temperature Ti in the lid space 6 and after gas supply ₎ . Using the gas pressure _{Pi_B} of the lid space 6 and the gas supply amount _ΔNi to the lid space 6, the gas substance amount _{Ni_A} of the lid space 6 before gas supply may be calculated.

Further, in the first to third embodiments, the case where the volume V of the lid space 6 is calculated using the design dimension or the measurement dimension of the radioactive material storage container 1 has been described as an example, but the present invention is not limited to this. , Modification is possible within a range that does not deviate from the gist of the present invention. For example, gas is supplied to the lid space 6 in a state where the used fuel is not stored in the internal space 3 of the radioactive material storage container 1, and the volume of the lid space 6 is used by using the value measured at that time. V may be calculated. To explain in detail, since the used fuel is not stored in the internal space 3 of the radioactive material storage container 1, it is considered that the gas temperature of the lid space 6 and the outer surface temperature of the secondary lid 5 are the same. The outer surface temperature of the secondary lid 5 is measured with a thermometer. Then, the gas temperature of the lid space 6, the amount of gas supplied to the lid space 6 measured by the flow meter 15, and the gas in the lid space 6 before and after the gas supply measured by the pressure gauge 11. The volume V of the lid space 6 may be calculated using the pressure (see the above equation (1)).

1 Radioactive material storage container 3 Internal space 4 Primary lid 5 Secondary lid 6 Lid space 11 Pressure gauge 15 Flow meter

Claims (4)

A radioactive material having an internal space for accommodating a radioactive substance, a primary lid covering the internal space, a secondary lid covering the primary lid, and a lid space formed between the primary lid and the secondary lid. For storage containers
A method for managing a radioactive material storage container, in which a gas filling operation for supplying gas to the lid space is performed in order to maintain a positive pressure state in the lid space.
During the gas filling operation this time, the lid is used by using the amount of gas supplied to the lid space measured by the flow meter and the gas pressure in the lid space before and after gas supply measured by the pressure gauge. The gas temperature of the lid space is calculated and the gas temperature of the lid space and the gas pressure of the lid space before the gas supply are used, or the gas temperature of the lid space and the gas temperature of the lid space after the gas supply are used. The amount of gas substance in the lid space before gas supply is calculated by using the gas pressure of the lid and the amount of gas supplied to the lid space.
Due to the difference between the amount of gas substance in the lid space after gas supply during the previous gas filling work and the amount of gas substance in the lid space before gas supply during the current gas filling work, during the previous gas filling work A method for managing a radioactive substance storage container, which comprises calculating the amount of gas leakage in the lid space during the period between the gas filling operation and the current gas filling operation. In the method for managing a radioactive material storage container according to claim 1,
The amount of gas substance in the lid space after gas supply during the first gas filling operation is the amount of gas supplied to the lid space measured by the flow meter during the first gas filling operation.
The amount of gas substance in the lid space after gas supply in each gas filling operation from the second time onward is the amount of gas substance in the lid space before gas supply in each gas filling operation and the gas to the lid space. A radioactive substance storage container characterized in that it is calculated by using the supply amount or by using the gas temperature of the lid space at the time of each gas filling operation and the gas pressure of the lid space after gas supply. Management method. In the method for managing a radioactive material storage container according to claim 1,
A method for managing a radioactive substance storage container, which comprises calculating the gas pressure in the internal space by assuming the amount of gas leakage in the lid space as the amount of gas increase in the internal space. In the method for managing a radioactive material storage container according to claim 1,
A radioactive substance storage container characterized in that the gas leakage rate in the lid space is calculated by dividing the amount of gas leakage in the lid space by the time between the previous gas filling operation and the current gas filling operation. How to manage.

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