JP4644150B2 - Safety evaluation method for air pallet transfer device - Google Patents

Description

  The present invention relates to a safety evaluation method for an air pallet transport device, for example, by analyzing behavior when an external force such as an earthquake is applied to an air pallet transport device that transports a storage container containing a radioactive substance. It relates to the technology to be evaluated.

  The fuel that has been used for a certain period in the core of the nuclear power plant facility is taken out of the core and temporarily stored in a spent fuel pool or the like. The fuel for which the predetermined cooling period has ended is finally transported to a reprocessing plant, where it is reprocessed and uranium and plutonium are taken out as reusable resources for reuse.

Currently, spent fuel generated at nuclear power plants is increasing along with power generation demand, so even if the reprocessing plant is in operation, the spent fuel generated in the country will exceed the processing capacity at the reprocessing plant, time to be reprocessed, need to be properly managed and stored.

As a method for managing and stored at-site or off-site of a nuclear power plant, the dry cask storage vault storage, ensiling, there are the method of wet storage system dry storage system and water pool concrete cask storage, etc., In view of cost and long-term stable storage, dry storage is attracting attention. Among dry storage systems, the cask storage system currently in practical use is a method of storing spent fuel in a dry cask that is a radioactive substance storage container.

  The cask includes a metal cask and a concrete cask, and the metal cask can be used for both transportation and storage. On the other hand, a concrete cask is a cask that is used for storage. During transportation, spent fuel is stored in a container called a canister, and the canister is stored in a transport cask and transported. In the storage facility, the metal cask is stored for a predetermined period as it is without transferring spent fuel.

  On the other hand, the canister is pulled out from the transport cask, loaded into a concrete cask prepared in advance, and stored for a predetermined period.

  Here, in the storage facility, when the cask is unloaded from the trailer by the overhead crane and transported to the storage position, the floor height of the storage building is increased to secure the space for moving and lifting the overhead crane, and the storage capacity of the cask is increased. Compared to, the storage building is large. Moreover, metal casks and concrete casks are usually very heavy (for example, about 100 to 200 tons), and a large overhead crane is required.

  In view of this, an air pallet type transfer device that can lower the floor height of a storage building has been proposed (Patent Document 1). The air pallet conveying apparatus of Patent Document 1 includes a self-propelled carriage having an air pallet that is mounted and fixed on a gantry and attached to the lower side of the gantry. At the time of transportation, the air pallet is mounted on the lower side of the cask gantry, and air is supplied from the carriage side to the air pallet so that the cask is floated and transported.

JP 2005-227198 A

  In the case of the air pallet conveyance device of Patent Document 1, it is considered that the friction coefficient between the air pallet and the ground is lowered due to levitation caused by the air blown from the air pallet, so that it has a certain vibration isolating function.

  However, safety when an external force such as an earthquake acts during transportation with the pallet on which the cask of the air pallet carrier is mounted, or when an external force such as an earthquake acts during storage with the gantry placed on the floor It is not clear about.

  The air pallet transport device that transports spent fuel should not affect the basic safety functions such as the cask confinement function, shielding function, heat removal function, and criticality prevention, even if tilted or slipped due to an earthquake, etc. Is required.

  However, it is not practical to evaluate the safety against earthquakes by conducting tests with actual machines, etc., because it takes a lot of time and cost, and it is not realistic to analyze the behavior of the air pallet transfer device by simulation etc. It is desirable to evaluate

  However, when analyzing the behavior of an air pallet transport device during an earthquake by simulation or the like, there is a problem that the program becomes enormous depending on the setting of the analysis model of the air pallet transport device, and analysis time is required.

  An object of the present invention is to realize a safety evaluation method capable of evaluating safety in a short time when analyzing the behavior of an air pallet or a cask when an external force is applied to an air pallet conveying device.

To solve the above problems, the present invention provides a floor by feeding a pedestal that is mounted cask for accommodating the spent fuel fixed, equipped with a plurality of airbags that loading the gantry compressed air to the air bag air pallet carrying device including a carriage which is arranged to form an air layer into two parallel for floating the platform, by an air motor which is attached to the carriage drive device for horizontally moving the carriage between the A safety evaluation method for analyzing the behavior when an external force is applied to the air pallet conveying device, combining the air pallet conveying device with simple elements such as concentrated mass, beam elements, spring elements, and gap elements. constructs for analysis model in gravel analysis capable beam mass model analyzes the time history of the behavior when an external force is exerted on the air pallet conveying apparatus using the model for the analysis Calculating the uplift amounts of one side of the frame for determining the presence or absence of falling of the slip amount of the frame to move sliding the floor from the maximum response displacement of the time history analysis result air pallet conveying apparatus, calculates The safety is evaluated by judging whether or not there is a collision with a surrounding structure from the slip amount, and the center of gravity of the air pallet transfer device passes through the fulcrum of the landing end of the gantry from the calculated lift amount. The safety is evaluated by determining whether the air pallet conveying device is overturned based on whether or not the line is exceeded . By the above method, the safety of the air pallet conveying device can be evaluated in a short time by analysis without carrying out a test using an actual machine or the like.

When carrying out safety assessment of air pallets by analysis, the behavior of air pallet transport equipment differs greatly when external force is applied in the floating state where the storage stand is levitated and in the landing state where the storage stand is placed. The analysis model is set separately for the floating state (conveyance state) and the landing state (storage state). Here, the landing state is a state where the air pallet does not float and the storage stand is not fixed. That is, the air pallet transfer device is combined with simple elements such as concentrated mass, beam elements, spring elements, and gap elements for behavior analysis when an external force is applied to the air pallet transfer device when the gantry is in a landing state. The analysis model is constructed with a beam mass point model capable of time history analysis, and the behavior when an external force is applied to the gantry using the analysis model is analyzed for time history, and the slide moves on the ground. Calculate the amount of lift of the gantry and the amount of lift on one side of the gantry to determine whether the air pallet transport device falls or not, and evaluate safety based on the calculated amount of slide and the amount of levitation In this case, the slip amount is determined when the acceleration when the external force of the floor surface on which the gantry is laid exceeds the product of the coefficient of friction and the gravitational acceleration between the gantry and the floor surface. The lift amount is calculated as the lift amount when one side of the mount is lifted by the rocking vibration of the mount, and the collision with the surrounding structure is calculated from the calculated slip amount. The air pallet is evaluated based on whether the center of gravity of the air pallet transport device exceeds the vertical line passing through the fulcrum of the landing end of the gantry from the calculated floating amount Evaluate safety by judging whether the transport device has fallen.

  Each part constituting the air pallet conveying apparatus is modeled by applying simple elements such as concentrated mass W, beam element B, spring element S, and gap element G. Thereby, a behavior can be analyzed in a short time by applying a known time calendar analysis (dynamic analysis) method.

  Furthermore, the analysis model can set directivity in a sliding direction by setting an initial gap between the air pallet transfer device and the floor surface.

  According to the present invention, safety can be evaluated in a short time when analyzing the behavior of an air pallet or cask when an external force is applied to the air pallet conveying device.

  FIG. 1 shows a schematic configuration plan view of an air pallet transfer apparatus according to an embodiment which is an object of safety evaluation of the present invention.

The air pallet transfer device includes a carriage 1 capable of self-propelling in a storage building and on a road, a compressed air source 5, and a mount 7 on which a cask 6 to be transferred is mounted.

A plurality of airbags 9 for providing levitation force to the carriage 1 are provided at the lower portion of the carriage 1, and a drive device 4 for driving the main body is provided at one end of the carriage 1. When the wheel 3 of the driving device 4 is driven with compressed air, the carriage 1 moves. Compressed air is supplied from the compressed air source 5 by the high pressure air hose 2.

  The cask 6 is fixed to the gantry 7 via the fixing bracket 8. The lower part of the gantry 7 has a structure in which the cart 1 can be inserted in the same manner as a pallet for carrying goods used in a normal factory or warehouse is inserted and conveyed by inserting a fork of a forklift.

  When transporting the cask 6, first, the air in the airbag 9 is removed to lower the carriage 1 and insert it under the mount 7. Next, when compressed air is put into the airbag 9, the airbag 9 is inflated and the carriage 1 is raised. When compressed air is further fed, a thin air layer is finally formed between the airbag 9 and the ground, and the carriage 1 is lifted.

  In the floating state, there is only a thin air layer between the airbag 9 and the ground, so the coefficient of friction with the ground is about 3/1000. That is, even when a weight of 100 tons is transported, if the ground is horizontal, it can move with a driving force of 300 kg at most, so the air motor of the driving device 4 may have a very small power.

  Here, since the cask 6 is a container for storing spent fuel, which is a radioactive substance, the behavior of the carriage 1 and the cask 6 when an external force such as an earthquake acts on the air pallet transfer device when the cask 6 is transferred. Needs to be confirmed that does not affect basic safety. Therefore, at the design stage, it is necessary to evaluate the behavior of the carriage 1 and the cask 6 when an external force is applied to the air pallet transport device, and to design a sufficient safety.

  FIG. 3 shows a flowchart of an embodiment of the safety evaluation method for the air pallet carrying device of the present invention. The safety evaluation method of the present embodiment includes a step of creating a simple model for behavior analysis (S103a), and “slip amount” and “lift amount” which are safety evaluation amounts by time history analysis (dynamic analysis). ”Is calculated (S103b) and safety is evaluated based on the calculated evaluation amount (S104).

  First, design information such as the structure of the storage facility, the cask 6 and the gantry 7 is taken in (S101). Next, an input condition 102 for analyzing the behavior of the air pallet transfer device is set (S102). Input conditions include design earthquake motion, building specifications (floor slope, friction coefficient), cask specifications (dimensions, weight, etc.), and the like. Next, behavior analysis is performed (S103). This behavior analysis is composed of two steps, a step of creating a simple model for analyzing the behavior of the air pallet transfer device to be evaluated (S103a), and an analysis using a time history method based on this model. The analysis step (S103b) calculates the “slip amount” and the “lift amount”, which are safety evaluation amounts.

  And the safety | security of an air pallet conveying apparatus is evaluated using the calculated slip amount and the amount of lift (S104). In this evaluation, the presence or absence of a collision with a surrounding structure is determined from the slip amount. Whether or not the air pallet conveying device falls is determined from the floating amount. For example, as shown in FIG. 4, when the center of gravity 13 of the cask 6 comes outside the vertical line 16 passing through the fulcrum 15 at one end of the gantry 7, the cask 6 falls over. Therefore, the lifting amount h at the other end of the gantry 7 in the state of FIG. 4 is set as the overturning condition H *, and if the calculated lifting amount h is less than H *, it will be assumed that the tipping will not be overturned. evaluate.

<Simple model creation: S103a>
In the air pallet conveying device, the behavior when an external force is applied is greatly different between the conveying state in which the gantry 7 is levitated and the storage state in which the gantry 7 is landed. Therefore, the model is created separately for the floating state (conveyance state) and the landing state (storage state).

(1) Simplified model in a floating state FIG. 5 shows an example of a method for creating a simple model in a floating state. The simple model of the present invention is characterized in that the air pallet conveying device is modeled by applying simple elements such as concentrated mass W, beam element B, spring element S, and gap element G.

  The model of the cask 6 gives a concentrated mass W and rotational inertia M to the node 21 at the center of gravity of the cask 6. The rigid beam element B is connected to the node 22 with the gantry 7 and the node 23 located above the cask 6. On the other hand, the models of the carriage 1 and the gantry 7 are simulated as rigid bodies because they have higher rigidity than the airbag 2 and the wheels 3. Further, the gantry 7 and the carriage 1 are connected by a frictional force due to the weight of the cask 6, and since the cask 6 is heavy, no slip occurs between them.

  The airbag 9 is simulated by the spring element Sa and the gap element Ga and is positioned at the center of each airbag 9. And the friction coefficient between the floor 12 and the airbag 9 is set to the gap element Ga. In the spring element Sa, the vertical rigidity is set based on the load displacement characteristic of the airbag 9 in the vertical direction. Further, the horizontal rigidity of the airbag 9 is set to a relatively small value because the deformation in the static frictional force is minute and the product is an elastic product such as rubber.

  The wheel 3 is simulated by the spring element St and the gap element Gt, and is simulated by being positioned at the center of each wheel 3. The horizontal and vertical rigidity of the wheel 3 related to the spring element St is set to a value obtained by a test or static analysis. In addition, the friction coefficient of the wheel 3 related to the gap element Gt varies depending on the material to be used. Therefore, the friction coefficient is obtained by a test or obtained by performing a parameter study.

  FIG. 6A shows a conceptual diagram of a model in a contact portion between the airbag 9 and the floor 3 of the wheel 3. Considering that the airbag 9 and the wheel 3 are in contact with the floor surface 12 without being constrained, they contact the node A of the floor surface 12 via gap elements Ga and Gt, and connect the node via spring elements Sa and St. A model is set by combining with the gantry 7 and the carriage 1 at B. The gap elements Ga, Gt represent axial contact and separation. Therefore, at the time of ascent, the relationship between the load F1 acting on the nodes A and B in FIG. 6A in the axial direction and the relative displacement X1 between the nodes A and B due to ascent is as shown in FIG. 6B. Become. When landing, the relationship between the load F2 acting on the nodes A and B in FIG. 6A in the direction perpendicular to the axis and the relative displacement X2 between the nodes A and B is as shown in FIG. 6C. In addition, it has slip characteristics with frictional force in the direction perpendicular to the shaft. The spring elements Sa and St are used to represent the elastic deformation of the airbag 9 and the wheel 3, and represent the subsidence due to its own weight and the deformation before sliding.

(2) Simple model of landing state FIG. 7 shows an example of a method for setting a simple model in the landing state. The simple model in the landing state is modeled by applying simple elements such as the concentrated mass W, the beam element B, the spring element S, and the gap element G to the air pallet transport device as in the analysis model in the floating state.

  A model used for the seismic response analysis in the landing state is created based on the friction coefficient between the floor surface 12 and the storage gantry 7 and the vibration characteristics and spring characteristics obtained from the detailed model. As for the cask 6, the concentrated mass W and the rotational inertia M are given to the node 21 at the position of the center of gravity as in the floating state. Further, since the cask 6 is a lump of metal and can be virtually regarded as rigid, the node 21 is connected to the node 22 with the gantry 7 and the node 23 positioned above the cask 6 by the rigid beam element B. It shall be. Here, the node 23 is a node provided for outputting the behavior of the top of the cask 6. Further, the rotational inertia M is adjusted so that the rotational inertia of the entire simple model of this embodiment is equivalent to that of the detailed model.

  Regarding the upper surface of the gantry 7, the simple model of this embodiment is two-dimensional, and the upper surface of the gantry 7 is simulated by a beam element Bb. Further, the bending rigidity of the beam element Bb on the upper surface is adjusted so as to match the primary natural frequency of the detailed model after setting the horizontal and vertical rigidity of the gantry 7 described later. The horizontal and vertical rigidity of the gantry 7 is simulated by the spring element Sb. This spring element Sb is set so as to have horizontal and vertical spring characteristics of the gantry 7 by static analysis of a detailed model. Further, since the gantry 7 is in contact with the floor 12 without being constrained, in this embodiment, the contact portion is shown in FIG. 5 using the gap element Gb and the spring element Sb as in the floating state. Modeling. Here, the gap element Gb represents the contact and separation in the axial direction, and has a sliding characteristic with a frictional force in the direction perpendicular to the shaft at the time of contact. The spring element Sb is used to represent elastic deformation of the gantry 7 and represents subsidence due to its own weight or deformation before sliding. Although the gantry 7 is continuously in contact with the floor surface, the gantry 7 is divided in the evaluation direction, and a plurality of gap elements Gb are set.

  Next, an example of the behavior pattern in the landing state is shown in FIG. As shown in FIGS. 8 (a) and 8 (b), in the landing state, the slippage becomes dominant, the rocking vibration becomes dominant, and the behavior changes depending on the state of the floor surface. Therefore, two types of simple models according to the present embodiment are created: a slip model that pays attention to slip, and a lift model that pays attention to lift of the end of the gantry accompanying rocking vibration.

(2-1) Slip Model in the Landing State FIG. 9 shows an example of the behavior when slipping in the ground state. Slip in the landing state is dominant mainly on the floor having a small coefficient of friction, and tends to have directivity in the sliding direction. As shown in FIG. 9, when the gantry 7 slides in the right direction, the right side of the gantry 7 is lifted right before sliding (a), and when the floor 7 is landed from that state, the gantry 7 slides in the right direction (b) and the left side (C). Therefore, modeling is performed to give directivity to the left and right sliding directions.

  FIG. 10 shows an example of a diagram in which an initial gap is provided on one side of the gantry 7 in the sliding model. As shown in FIG. 10 (a), when the initial gap 31 is provided on one side of the gantry 7, the opposite side where the initial gap 31 is provided is likely to float as shown in FIG. 10 (b). As a result, as shown in FIG. 5C, since it becomes easy to slide to the side opposite to the initial gap 31, directivity can be given in the sliding direction.

  Here, the concept and creation method of the slip model provided with the initial gap 31 will be described with reference to FIG. The friction coefficient between the floor 12 and the gantry 7 is set in consideration of the fact that it differs depending on the material used. The initial gap 31 is set to the maximum value obtained from the manufacturing tolerance of the gantry 7 and the flatness of the floor surface, or a parameter study is performed. The initial gap 31 is set by dividing the gantry 7 into a plurality of elements from one or both ends of the gantry 7 as in the example shown in FIG. Thus, by providing the initial gap 31 on one side or both sides of the gantry 7 in the slip model, directivity can be given in the slip direction.

(2-2) Lifting model in the landing state The phenomenon in which the mount 7 on which the cask 6 is mounted in response to an external force in the landing state is mainly dominant in the case of the floor surface 12 having a relatively large friction coefficient. In particular, it is characterized by the occurrence of rocking vibration accompanied by lifting. Therefore, in order to model the rocking vibration, a model with an initial gap is created while supporting the horizontal direction of the bottom so that the mount does not slide.

  FIG. 12 shows an example in which an initial gap is provided in the floating model. The initial gap is provided on both sides as shown in FIG. However, an initial gap can be set on one side depending on the state of the floor surface 12.

  The horizontal direction of the bottom of the gantry 7 is constrained, and the initial gap is set to the maximum value obtained from the manufacturing tolerance of the gantry and the flatness of the floor surface, or a parameter study is performed. The initial gap is set by a plurality of elements from both ends of the gantry 7 as in the example shown in FIG.

  As described above, in the floating model, the horizontal direction of the gantry 7 is constrained, and the initial gap is provided on one side or both sides of the gantry 7, thereby enabling rocking vibration.

<Time history analysis: S103b>
In the time history analysis (S103b), the “slip amount” and the “lift amount”, which are safety evaluation amounts, are calculated by a known time history analysis (dynamic analysis) using the simple model created in S103a.

  Dynamic analysis is executed based on a simple model according to analysis conditions set as the input condition 102, for example, design ground motion, building specifications (floor slope, friction coefficient), cask specifications (size, weight, etc.), etc. . In the analysis using the simple model of the floating state, “slip amount” and “lift amount” during transportation are calculated. The analysis using the simple model of the landing state calculates the “slip amount” and “lift amount” during storage.

<Safety evaluation: S104>
In the safety evaluation, the “slip amount” and the “lift amount” calculated in the time history analysis S103b are compared with the evaluation criteria to evaluate the safety of the air pallet transport device. As for “slip amount”, it is determined whether or not there is a collision with a surrounding structure in the conveyance path or a collision with a structure around the storage position. As for the “lift amount”, it is determined whether or not the air pallet conveying device is overturned. For example, as shown in FIG. 4, when the center of gravity 13 of the cask 6 comes outside the vertical line 16 passing through the fulcrum 15 at one end of the gantry 7, the cask 6 falls over. The amount of rising at this boundary is set as the overturning condition H *, and the calculated amount of rising h is compared with the overturning condition H *. If h <H *, it is determined that no overturning occurs.

  FIG. 13 shows a flowchart of the procedure of another embodiment of the method for evaluating the safety of the air pallet carrying apparatus of the present invention. This embodiment is different from the embodiment shown in FIG. 3 in that a simple safety evaluation (S105) is applied instead of the time history analysis (S103b). This simple safety evaluation (S105) is not applied to the floating state evaluation, but only to the safety evaluation method using the simple model in the landing state. Since others are the same as those in FIG. 3, the same reference numerals are given and description thereof is omitted.

  In FIG. 13, the simplified safety evaluation (S105) is a simplified behavioral phenomenon in the state where an external force is applied to the air pallet transfer device. This simple safety evaluation method is a safer evaluation than the safety evaluation using the analysis, and the calculation cost can be reduced.

  The behavior in the landing state changes depending on the floor surface state, such as slip becomes dominant or rocking vibration becomes dominant. Therefore, in the simple safety evaluation (S105) of the present embodiment, an evaluation focusing on slip and an evaluation focusing on lifting of the end of the gantry accompanying rocking vibration are performed.

(1) Simple slip evaluation in the landing state FIG. 14 shows an example of the concept of slip evaluation in the simple safety evaluation method. In the slip evaluation, the slip in the landing state is considered to be a slip of a rigid body, and the slip amount is the largest in a complete slip state without any frictional resistance. The slip amount at this time is the relative displacement between the cask 6 and the floor surface 12, but the slip amount of the cask 6 is completely zero, so the slip amount is the displacement of the floor surface 12 itself. On the other hand, based on past knowledge, it has been confirmed that the sliding behavior in the cask landing state tends to have directivity in the sliding direction. The slip amount in the above-described perfect slip state has both amplitudes, and the slip amount is canceled for return. Therefore, in order to express a state in which the slip amount is accumulated, the slip amount is obtained on the assumption that the slip state in one direction is a complete slip state in one direction and a fixed state in the opposite direction.

  As shown in FIG. 14 (a), when the floor displacement increases, the slipping state is complete, and the cask 6 remains stopped, so the relative displacement increases. As shown in FIG. 5B, when the floor displacement decreases, the fixed state is established, and the cask moves together with the floor, so that the relative displacement does not change. As a calculation method, two types are calculated, one that adds the floor displacement when the speed is positive and the other that adds when the speed is negative, and the larger addition result is adopted. This is the safest slip evaluation.

  The actual slip does not always occur when an external force is applied to the cask, but slips only when the inertia force of the cask exceeds the static friction force. Since the inertial force of the rigid body placed on the floor surface is obtained by multiplying the acceleration of the floor surface by the mass, the presence / absence of slippage can be determined from the acceleration value of the floor surface. That is, slip occurs when “floor acceleration> friction coefficient × gravity acceleration”. In the above-described addition of floor displacement, by limiting the calculation time range only to slip, the evaluation value of the slip amount becomes close to an actual phenomenon.

(2) Simple lift evaluation in the landing state Since the floating in the landing state appears greatly when rocking vibration occurs, a simple evaluation method can be derived from the characteristics of the rocking vibration of the rigid body. First, the frequency range to be examined for rocking vibration is described.

  FIG. 15 shows an example of an explanatory diagram for the locking equivalent frequency. Assuming that the rocking frequency is f, as shown in FIG. 15, assuming that the landing time from a certain lift h is t, and assuming that the time obtained by multiplying t by 4 is one cycle, the rocking equivalent frequency f is Can be sought. Therefore, t and f are obtained from the following equations. In the equation, θ is the inclination angle of the cask 6, a is the distance between the inclination fulcrum and the center of gravity, α is (90 ° −θ), and g is the gravitational acceleration.

検討すべき周波数範囲は、転倒条件である浮上り量Ｈ*に対して十分小さい値とする。次に、ロッキング振動の応答値について、ロッキング振動時のキャスク６の振動特性がロッキング周波数と等しい固有振動数であると仮定すると、重心１３の応答値は応答スペクトルにより求められる。また、ロッキング周波数は応答値により変化するが、ロッキング周波数が取りうる範囲の固有振動数を対象に応答スペクトルの最大値を求めればロッキング振動の応答値は包絡される。

The frequency range to be examined is a sufficiently small value with respect to the lift amount H * that is the overturning condition. Next, regarding the response value of the rocking vibration, assuming that the vibration characteristic of the cask 6 at the time of the rocking vibration is a natural frequency equal to the rocking frequency, the response value of the center of gravity 13 is obtained from the response spectrum. Further, the rocking frequency varies depending on the response value. If the maximum value of the response spectrum is obtained for the natural frequency within the range that the rocking frequency can take, the rocking vibration response value is enveloped.

FIG. 16 shows an example of a relationship diagram between the center of gravity of the cask 6 and the lift amount. From the concept of FIG. 15, the floating amount h due to rocking vibration can be calculated by the following procedure. First, the maximum speed v of lifting is obtained from the speed response spectrum for the natural frequency in the range that the rocking frequency f can take. Next, assuming that the kinetic energy due to the maximum velocity is converted into potential energy, the floating amount h _{0 of the} center of gravity is obtained by the following equation. In addition, g is a gravitational acceleration.

そして、図１６に示すように、重心の浮上り量ｈ_０が発生した時の架台端部の浮上り量ｈを算出し、転倒条件である浮上り量Ｈ*と比較することにより、転倒の有無を評価することができる。

Then, as shown in FIG. 16, the lift amount h of the gantry end when the lift amount h ₀ of the center of gravity occurs is calculated, and compared with the lift amount H * which is the fall condition, The presence or absence can be evaluated.

  In the first and second embodiments described above, the safety evaluation method of the present invention has been described as an example in which the method is applied to an air pallet transport apparatus related to transport and storage of a cask that stores radioactive materials, but the present invention is not limited to this. Needless to say, general heavy objects can be applied to an air pallet conveying apparatus for conveying and storing.

It is a schematic block diagram of one Example of an air pallet conveying apparatus. It is sectional drawing of one Example of an air pallet. It is a flowchart which shows the procedure of one Example of the safety evaluation method of the air pallet conveying apparatus of this invention. It is a figure explaining the view of the simple model setting of the air pallet conveying apparatus in the floating state. It is a figure which shows one Example of the simple model of the air pallet conveying apparatus in the floating state. It is a figure explaining the idea of the simple model setting of the contact part of the air pallet conveying apparatus in the floating state. It is a figure which shows one Example of the simple model of a cask and a mount frame in a landing state. It is a figure explaining the vibration pattern of a cask and a mount in a landing state. It is a figure explaining the behavior at the time of sliding of a cask and a mount in the landing state. It is a figure which shows an example which provided the one side gap in the slip model of the cask and mount frame in the landing state. It is a figure explaining setting an initial gap to a slip model of a cask and a stand in the landing state. It is a figure which shows an example which provided the initial stage gap in the slip model of the cask in a landing state, and a mount frame. It is a flowchart which shows the procedure of one Example of the safety evaluation method of the air pallet conveying apparatus to which the simple safety evaluation method in a landing state is applied. It is a figure explaining the idea of the slip evaluation of a simple safety evaluation method. It is explanatory drawing about the rocking equivalent frequency of the simple safety evaluation method. It is a figure explaining the relationship between the gravity center of the cask of the simple safety evaluation method, and the floating amount.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Carriage 2 ... Air hose 3 ... Wheel 4 ... Drive device 5 ... Compressed air source 6 ... Cask 7 ... Base 8 ... Fixed metal fitting 9 ... Air bag 10 ... Air layer

Claims (4)

Wherein forming an air layer frame between a frame that is equipped with a cask for accommodating the spent fuel fixed, a plurality of equipped with airbags floor by feeding compressed air to the air bag for loading the cradle and two carriages arranged in parallel to float, a safety evaluation method of the air pallet carrying device including a drive device for horizontally moving the carriage by attached air motor to the carriage, the air pallet conveying apparatus For analysis of the behavior when external force is applied to the air pallet, the air pallet transfer device is used for analysis with a beam mass model capable of time history analysis by combining simple elements such as concentrated mass, beam elements, spring elements, and gap elements. building a model to analyze time history behavior when an external force is exerted on the air pallet conveying apparatus using the model for the analysis, the maximum response displacement of the time history analysis result The sliding amount of the gantry that slides on the floor surface and the floating amount on one side of the gantry for judging whether the air pallet transport device falls or not are calculated, and the surrounding structures are calculated from the calculated sliding amount. The presence or absence of a collision is judged and safety is evaluated, and based on whether the center of gravity of the air pallet transport device exceeds the vertical line passing through the fulcrum of the landing end of the gantry from the calculated floating amount A safety evaluation method for an air pallet transport device that evaluates safety by determining whether the air pallet transport device is overturned . A frame that spent fuel equipped with a cask for accommodating the fixing, the frame to form an air layer between the ground by feeding compressed air into equipped with multiple air bags to loading the cradle said airbag and two carriages arranged in parallel to float, a safety evaluation method of the air pallet carrying device including a drive device for horizontally moving the carriage by attached air motor to the carriage, before Symbol cradle implantation Time history analysis is possible by combining the air pallet transport device with simple elements such as concentrated mass, beam element, spring element, and gap element to analyze the behavior when external force is applied to the air pallet transport device in the state. constructs for analysis model in beam mass model analyzes the time history of the behavior when an external force is exerted on the frame by using a model for the analysis, move sliding the ground And slippage of the frame, said calculating the uplift amounts of one side of the frame for determining the presence or absence of falling of the air pallet conveying apparatus, safety on the basis of said uplift amount and the slip amount issued calculated in evaluating the slip of acceleration when said cradle worked external force of implantation has been floor, slip when it exceeds the product of the friction coefficient and the gravitational acceleration of the platform and the floor surface There is calculated as occurring, the amount Ri said levitation collision with the calculated the uplift amount when the rocking of the cradle Thus the one side of the cradle lifted, structures around from the calculated said slippage The air pallet is evaluated based on whether the center of gravity of the air pallet transport device exceeds the vertical line passing through the fulcrum of the landing end of the gantry from the calculated floating amount If the transport device falls Safety evaluation method of the air pallet conveying apparatus determines to assess the safety of. The analysis model is divided into a floating state and a landing state of the storage stand, the cask, the storage stand, and the drive device are simulated with beam elements, the wheels of the drive device, the air pallet, 3. The simplified model formed by simulating the storage frame with a gap element and a spring element and created as a concentrated load and rotational inertia act on the center of gravity of the cask. 4. Safety evaluation method for air pallet transfer equipment. The simple model is formed on the side that collides with the floor surface when colliding with the floor surface after one side of the cradle is lifted by rocking vibration generated when an external force is applied to the air pallet conveying device . By utilizing the phenomenon that the air pallet conveying device slips in the direction, an initial gap is set between one side of the gantry of the air pallet conveying device and the floor surface, and the side where the initial gap is not set is set. By facilitating the floating of the gantry, it is easy to generate a collision with the floor and a slip on the side where the initial gap is not set, and the air when an external force is applied to the air pallet transfer device. 4. The safety evaluation method for an air pallet transport apparatus according to claim 3, wherein directivity is provided in a sliding direction of the pallet transport apparatus.

Images