Packaging for storing radioactive materials, having an improved design for monitoring the temperature of a gasket associated with the packaging lid

Abstract

The invention relates to a packaging (1) for storing radioactive materials, comprising a packaging body (8) defining a containment chamber (10) and including a lateral packaging body (14), a bottom (16) and a lid (18) comprising a lid body (18a). The packaging comprises a gasket (22a, 22b) constrained between a first surface (S1) of the lid body (18a), and a second surface (S2) of an element (18b, 24) adjacent to the lid body (18a). The packaging comprises a temperature sensor (30) for determining a temperature of the gasket, the sensor being mounted on a third or fourth outer surface (S3, S4) of the packaging body (8), the third surface (S3) being an outer surface of the lid (18), and the fourth surface (S4) being an outer surface of the axial end portion (24).

Description

[0001] 43359 AP

[0002] 1

[0003] DESCRIPTION

[0004] TITLE: PACKAGING FOR THE STORAGE OF RADIOACTIVE MATERIALS, FEATURING AN IMPROVED DESIGN FOR TEMPERATURE MONITORING OF A SEAL ASSOCIATED WITH THE PACKAGING LID

[0005] 5. TECHNICAL DOMAIN

[0006] The present invention relates to the field of packaging for the storage of radioactive materials. It concerns more particularly the problem of the long-term durability of the seals ensuring the airtightness of this packaging.

[0007] Radioactive materials intended to be stored in the packaging according to the invention

[0008] 10 are, for example, spent fuel assemblies, or any other radioactive material releasing residual thermal power.

[0009] PREVIOUS STATE OF THE ART

[0010] A container for the storage of radioactive materials typically comprises a container body that internally defines a containment chamber within which

[0011] 15 are housed the radioactive materials. The packaging body has different components, such as a side packaging body, a base, and a removable lid mounted on this side body.

[0012] To meet regulatory safety requirements, the containment unit must remain leak-proof throughout the storage period. To achieve this, one or more seals are generally fitted to the packaging, particularly between the lid and the side panel, or between different components of the lid.

[0013] These seals, usually metallic, are exposed to high temperatures of around 100°C, resulting from the heat generated by the radioactive materials stored within the containment structure of the packaging. These seals, located in a

[0014] 25. The internal zone of the packaging is thus subject to thermal aging effects which, in particular, lower the minimum compression ratio of the seals required to guarantee the level of sealing necessary for safety demonstrations. 43359 AP

[0015] 2

[0016] To meet the aforementioned requirements, during the packaging design phase, safety studies are conducted to evaluate the temperature of the seals and demonstrate that their minimum compression ratio after aging remains above an permissible value defined in the safety demonstrations. These studies lead to the determination of a duration

[0017] The theoretical lifespan of each seal in the packaging is estimated at 5, depending on the packaging's temperature profile and the duration of seal use during packaging operations when loaded with its radioactive contents. However, the conservative assumptions used in these studies mean that the actual lifespan of the seals is often longer than their theoretical lifespan, as determined by these studies.

[0018] However, prior art has not yet provided any realistic and effective solutions for fully exploiting these available margins. For example, one approach has been to install a temperature sensor on the seal itself, or near the seal within the containment chamber. However, this solution remains problematic given

[0019] 15. The sensor must not compromise the containment function of the radioactive material, although this function could be affected by the necessary passage of an instrumentation cable through the packaging. Furthermore, in the event of a sensor failure, its replacement would require opening the containment structure and unloading the radioactive materials, which are very complex, time-consuming, and costly operations. These constraints remain too significant to consider implementing this solution.

[0020] Therefore, there remains a need to identify a reliable, simple, and inexpensive technical solution that could potentially extend the lifespan of a packaging seal, compared to its theoretical lifespan.

[0021] 25. Since replacing such seals is a technically complex, costly, and time-consuming operation, extending the lifespan of a seal would consequently increase the storage time of radioactive materials without requiring seal replacement. 43359 AP

[0022] 3

[0023] DESCRIPTION OF THE INVENTION

[0024] To meet this need, the invention first relates to packaging for the storage of radioactive materials, the packaging comprising a packaging body defining a containment enclosure for the radioactive materials, the packaging body

[0025] 5 comprising a side body of packaging extending around a longitudinal axis of the packaging, and a base and a removable lid spaced apart along the longitudinal axis, the removable lid comprising a lid body fixed to an annular axial end portion of the side body of packaging, the packaging comprising a seal constrained between a first and a second facing surface belonging to the packaging body, the first surface being a surface of the lid body, and the second surface being a surface of a packaging element adjacent to the lid body.

[0026] According to the invention, the packaging also includes a temperature sensor for determining the temperature of said sealing gasket, the sensor being mounted on a

[0027] 15 third or a fourth external surface of the packaging body, the third surface being an external surface of the lid, and the fourth surface being an external surface of the annular axial end portion of the side packaging body.

[0028] Numerical studies conducted by the inventors have indeed demonstrated that the temperature of such a seal can be assessed with low uncertainty from outside the packaging by measuring the temperature of the lid or the annular axial end portion of the packaging's side panel. For example, numerical calculations showed a difference of only about 2 to 3°C between the actual temperature of a point of interest on the seal and a measurement point on one of the aforementioned third and fourth surfaces, located outside the body.

[0029] 25 packaging.

[0030] The ability to determine, during storage, the actual temperature experienced by the sealing gasket from outside the packaging reduces the reliance on theoretical prior art studies. Furthermore, the invention provides a simple, proven, inexpensive, and non-dosing solution, potentially enabling 43359 AP

[0031] 4. Extend the life of the sealing gasket by monitoring its temperature during storage.

[0032] The invention also preferably has at least one of the following optional features, taken individually or in combination.

[0033] 5 Preferably, at least part of the sensor is arranged in a space internally delimited by a fictitious conical surface of revolution oriented so as to open towards the outside of the packaging, and having the following characteristics:

[0034] - a vertex corresponding to a point on the joint, where we want to measure the temperature;

[0035] - an axis of revolution parallel to a radial or longitudinal direction of the packaging; and

[0036] - an angle A, defined between the axis of revolution and a generatrix of the fictitious conical surface, less than or equal to 70°, and preferably less than or equal to 45°.

[0037] With this arrangement, determining the temperature of the seal from outside the packaging body proves to be advantageously even more reliable.

[0038] 15 Preferably, at least part of the sensor is traversed by a fictitious axis passing through a point of the joint, and parallel to the radial or axial direction. This also helps to increase reliability.

[0039] Preferably, the sensor is positioned axially beyond the containment chamber, in the direction of the lid. This particular arrangement also improves measurement reliability by reducing calculation uncertainties. Indeed, beyond the containment chamber, the sensor's local temperature is less dependent on the potential heterogeneity of the thermal load, and the correction applied to the external measurement is less sensitive to the thermal power profile of the radioactive material content.

[0040] 25 Alternatively, the temperature sensor is a non-contact sensor, taking for example the form of an infrared temperature sensor.

[0041] Preferably, the sensor is connected to an automatic temperature recording device. Preferably, the packaging element adjacent to the lid body is the annular axial end portion of the side packaging body. 43359 AP

[0042] 5

[0043] In this scenario, the annular axial end portion of the packaging side body preferentially defines an axial recess to house at least part of the lid body, and the first and second opposing surfaces are respectively an internal surface of the lid body and a bottom axial surface of the recess.

[0044] 5. An analogous solution remains possible by implanting the joint between radially facing surfaces provided on these two elements, without departing from the scope of the invention.

[0045] According to another possibility, the packaging element adjacent to the lid body is a lid element, corresponding to a plug sealing a passage through the lid body, for example a drainage hole, and the first and the

[0046] 10 second surfaces in comparison are respectively an external surface of the lid body, and an internal surface of the sealing cap.

[0047] In this case, the external surface of the lid body preferably has an axial recess for housing at least part of the sealing plug, and the first surface is the axial bottom surface of the recess.

[0048] Finally, the packaging preferably includes a protective cover in case of an air accident, the cover covering at least partially, axially and radially, the annular axial end portion of the lateral body of the packaging.

[0049] The invention also relates to an assembly comprising such packaging, as well as an electronic device configured to generate, from a temperature of

[0050] 20 reference measured and delivered by said temperature sensor, a temperature of the sealing gasket, by applying a correction to the reference temperature.

[0051] The invention also relates to a method for determining the temperature of the sealing gasket in such packaging, comprising the following steps:

[0052] - measurement of a reference temperature using the temperature sensor;

[0053] - application of a correction to the reference temperature, in order to determine a seal temperature.

[0054] The invention also relates to a method for monitoring the temperature of the sealing gasket in such packaging, preferably during a storage period of this packaging, the monitoring method being carried out by a repetitive implementation of the method

[0055] 30. Determining the temperature of the sealing gasket as shown above. 43359 AP

[0056] 6

[0057] Other advantages and features of the invention will appear in the detailed, non-limiting description below.

[0058] BRIEF DESCRIPTION OF THE DRAWINGS

[0059] This description will be made with reference to the attached drawings, among which are;

[0060] 5 [Fig. 1] represents a schematic longitudinal cross-sectional view of a packaging for the storage of radioactive materials, in a vertical position, according to a first preferred embodiment of the present invention;

[0061] [Fig. 2] represents an enlarged view of part of the packaging shown in figure 1;

[0062] [Fig. 3] is an enlarged schematic view of part of that of the previous figure, showing more particularly a temperature sensor;

[0063] [Fig. 4] is a view similar to the previous one, showing an alternative implementation;

[0064] [Fig. 5] represents a view similar to that of figure 2, according to an alternative embodiment;

[0065] [Fig. 6] shows a view similar to that of Figure 2, with the packaging presented

[0066] 15 in the form of a second preferred embodiment of the invention;

[0067] [Fig. 7] represents a view similar to that of figure 2, according to an alternative embodiment;

[0068] [Fig. 8] represents a view similar to that of figure 2, with the packaging presented in the form of a third preferred embodiment of the invention;

[0069] [Fig. 9] represents a view similar to that of figure 8, according to an alternative embodiment;

[0070] [Fig. 10] represents a view similar to that of figure 8, according to another alternative embodiment;

[0071] [Fig. 11] represents a schematic view of the packaging, presented in the form of a

[0072] 25 fourth preferred embodiment of the invention; and

[0073] [Fig. 12] is a schematic view representing steps in a process for monitoring the temperature of a seal in the packaging shown in the preceding figures. 43359 AP

[0074] 7

[0075] DETAILED EXPLANATION OF PREFERRED METHODS OF IMPLEMENTATION

[0076] Referring first to Figure 1, a container for storing radioactive materials, such as spent fuel assemblies, is shown. The container 1, shown in its vertical storage position in Figure 1, has a longitudinal axis

[0077] 5 2 centered on this packaging, and parallel to a longitudinal direction 4, also called the height direction or axial direction. The packaging also has a radial direction 6, orthogonal to the longitudinal direction 4.

[0078] The packaging 1 comprises a packaging body 8, which defines a containment enclosure 10 for the radioactive material 12, namely a leak-proof enclosure. The packaging body 8 has a lateral packaging body 14, extending around the longitudinal axis. Its cross-section is, for example, circular, but it may alternatively be polygonal, for example hexagonal.

[0079] The packaging body 8 also includes a base 16 and a removable lid 18 spaced apart along the longitudinal axis 2. This lid 18 contributes to the

[0080] 15. Delimitation of the containment enclosure 10, by cooperating with a sealing gasket, as will be described below. In a known manner, a secondary cover may be added adjacent to the cover 18, this secondary cover not preferentially participating in the delimitation of the containment enclosure.

[0081] The cover 18 can be made in one piece or of multi-component design. In the first preferred embodiment of the invention, shown in Figure 1, the removable cover 18 comprises a cover body 18a, forming the vast majority of the cover. The latter also includes a sealing plug 18b for a passage 20 through the cover body 18a, opening into the containment chamber 10. This is preferably a passage 20 for the

[0082] 25 drainage of the containment structure, used in particular after underwater loading of radioactive materials 12.

[0083] Apart from these drainage operations, during which the passage 20 is traversed by a drainage tube from the enclosure 10, this passage is sealed by the plug 18b, which ensures the orifice is watertight. In this respect, the plug 18b 43359 AP

[0084] 8 contributes to the delimitation of the containment enclosure 10, and therefore belongs to the packaging body 8. To meet safety requirements, a sealing gasket 22a is axially constrained between the cap 18b and the lid body 18a. Fastening elements 27, shown only schematically in Figure 1 and corresponding by

[0085] 5 examples with screws and / or bolts allow the cap 18b to be assembled onto the lid body, and the desired force to be applied to the sealing gasket 22a.

[0086] The sealing gasket 22a, which is annular in shape and preferably eccentric with respect to axis 2, is preferably metallic, for example with a circular half-cross-section.

[0087] Furthermore, also to meet regulatory safety requirements, a sealing gasket 22b is axially constrained between the lid body 18a and an annular axial end portion 24 of the side packaging body 14. To apply the required force to achieve the correct level of gasket compression, the lid body 18a is removably fixed to the aforementioned annular axial end portion 24, for example

[0088] 15 using fasteners, preferably of the screw and / or bolt type 26 shown schematically only in Figure 1.

[0089] Alternatively, the lid body 18a can be indirectly fixed to the side body of the packaging. In this particular case, the fixing devices allow a flange to be fixed to the annular axial end portion 24 of the side packaging body 14, which then rests against the lid body 18a, in order to ensure that it remains in position on the side packaging body.

[0090] The sealing gasket 22b, which is annular in shape and centered on axis 2, is also preferably metallic, for example with a circular half-cross-section.

[0091] The components of the packaging body 8, such as the lid body 18a, are

[0092] 25 preferably made of steel, and more particularly of forged steel for the assembly formed by the base 16 and the side body of packaging 14.

[0093] In addition, shock-absorbing covers 28 can cover the opposite annular axial end portions of the lateral body 14, as shown in Figure 1. This covering by each shock-absorbing cover 28, partial or total, is carried out at both 43359 AP

[0094] 9 axially and radially. These are preferably protective covers in case of an air accident.

[0095] The distinctive feature of the invention lies in the provision of a constrained sealing joint 22a, 22b between a first surface SI and a second facing surface S2 belonging

[0096] 5 to the packaging body 8, the first surface S1 being a surface of the lid body 18a, and the second surface S2 being a surface of a packaging element 18b, 24 adjacent to the lid body 18a. A temperature sensor 30 is added for determining the temperature of the sealing gasket 22a, 22b, this sensor being mounted on a third surface S3, or on a fourth external surface S4 of the body

[0097] 10 of packaging 8. The third surface S3 is an external surface of the lid 18, and the fourth surface S4 is an external surface of the annular axial end portion 24 of the lateral packaging body 14. As an example, several sensors can be placed around the periphery to manage circumferential thermal gradients, for example every 90°.

[0098] In the first preferred embodiment of Figure 1, shown in more detail in Figures 2 to 4, it is the temperature of the seal 22b that is monitored / determined using the sensor 30. The aforementioned packaging element, adjacent to the lid body 18a, corresponds here to the annular axial end portion 24 of the side packaging body 14. This end portion 24 defines an axial recess 32 for the housing at least in

[0099] 20 part of the lid body 18a. Thus, the first surface SI here corresponds to an internal surface of the lid body 18a, oriented towards the bottom 16 and the containment enclosure 10, while the second surface S2, which is axially opposite it, corresponds to an axial bottom surface of the recess 32.

[0100] In this first preferred embodiment, the temperature sensor 30 is fixed externally to the packaging body 8, and more precisely to the fourth surface S4 corresponding to the external surface, oriented radially outwards, of the annular axial end portion 24 of the lateral packaging body 14. Preferably, the sensor 30 is arranged lower than the upper shock-absorbing cover 28, so as not to be covered by the latter, although such an arrangement remains conceivable, without departing from the scope of

[0101] 30 The invention. 43359 AP

[0102] 10

[0103] In order to obtain increased reliability for determining the temperature of the seal 22b, using the sensor 30 arranged externally to the body 8, it is preferable that at least a part of this sensor 30 is arranged in a space 34 delimited internally by a fictitious conical surface of revolution 36, shown on

[0104] 5. Figure 2. This characteristic reflects the fact that the sensor 30 is located directly above or nearly directly above the seal 22b, in the radial direction 6. Indeed, this fictitious conical surface 36 has an apex corresponding to a point 38 on the seal 22b, preferably its center in the longitudinal half-section of the packaging passing through the sensor 30, as shown in Figure 2. Furthermore, its axis of revolution 40

[0105] 10 is parallel to the radial direction 6 of the packaging, while an angle A defined between the axis of revolution 40 and a generatrix 42 of the fictitious conical surface 36 remains less than or equal to 70°, and even more preferably less than or equal to 45°. Furthermore, as is clear from the above, the fictitious conical surface 36 is oriented so as to open outwards from the packaging, here radially outwards. The tip of this conical surface 36, formed by its apex 38, is therefore preferably oriented towards the axis 2 of the packaging.

[0106] To further enhance the reliability of the temperature determination of the seal 30, at least part of the sensor 30 is traversed by a fictitious axis passing through a point on the seal, and parallel to the radial direction 6. Typically, this fictitious axis corresponds to the axis

[0107] 20 of revolution 40 mentioned above, passing through the center of the joint 22b in half-section.

[0108] In these scenarios, the small radial distance between the seal 22b and the sensor 30, as well as the material continuity within the annular axial end portion 24 of the packaging side body 14, combined with the good conductivity of the steel forming this portion, significantly reduces uncertainties in determining the seal temperature. Indeed, numerical calculations have demonstrated a small difference of approximately 2 to 3°C between the actual temperature of a point of interest on the sealing gasket 22b and the measurement point on the fourth surface S4 of the packaging body 8.

[0109] To further facilitate the correlation between these two temperatures, namely that

[0110] 30 measured at surface S4 with sensor 30, and that of joint 22b to be determined, this sensor 43359 AP

[0111] 11

[0112] 30 is preferentially arranged axially beyond the containment enclosure 10, in the direction of the cover 18. In this position, the local temperature of the sensor 30 is less subject to the potential heterogeneity of the thermal loading, and the correction to be applied to the external measurement by the sensor is less sensitive to the thermal profile of

[0113] 5. Power of radioactive materials 12.

[0114] In this regard, it is noted that the invention can be implemented using a single sensor 30, or using several identical or similar sensors to the one described above. In the latter case, the sensors are preferably spaced circumferentially from each other, and also preferably all traversed by a fictitious plane.

[0115] 10 corresponding to a plane of the sealing joint 22b.

[0116] The multiplicity of sensors allows for obtaining more precise data on the temperature of the seal to be determined, in particular because several angular sectors of this seal are temperature probed, always from outside the lateral body of packaging 14.

[0117] Referring to Figure 3, the temperature sensor 30 is preferably mounted magnetically on the fourth surface S4. To achieve this, it comprises a housing 44 equipped, on one of its open faces, with a permanent magnet 46 that contacts the fourth surface S4. Furthermore, inside the housing, the sensor 30 includes a sensitive element 48 that is forced into contact with the fourth surface S4 by a return spring 50 housed inside this housing 44.

[0118] 20 According to an alternative shown in Figure 4, the temperature sensor 30 is a non-contact sensor, for example in the form of an infrared temperature sensor, equipped with a transmitter 52 and a receiver 54 held at a distance from the fourth surface S4, on which the temperature is measured. Alternatively, as a temperature sensor, a non-contact infrared thermometer could be used to remotely measure the temperature of a point of interest on the surface S4.

[0119] Figure 5 shows an alternative to the first preferred embodiment, in which the sealing gasket 22b remains clamped between the same surfaces S1 and S2 as before. Only the position of the temperature sensor 30 changes; it is mounted on the third surface S3, corresponding here to an external surface of the cover body 18a.

[0120] 30 oriented axially in the opposite direction to that of the containment enclosure 10. 43359 AP

[0121] 12

[0122] With the aim of further improving the reliability of determining the temperature of the seal 22b, using the sensor 30 arranged externally on the cover 18, it is preferentially arranged that at least a portion of this sensor 30 is located in a space 134 delimited internally by a conical fictitious surface of

[0123] 5 revolution 136, represented in figure 5. This characteristic reflects the fact that the sensor 30 is located directly or substantially directly above the seal 22b, in the axial direction 4. Indeed, this fictitious conical surface 136 has a vertex corresponding to a point 138 of the seal 22b, preferably its center in the longitudinal half-section of the packaging passing through the sensor 30, as shown in figure 5. In addition, its axis of revolution 140 is parallel to the axial direction 4 of the packaging, while an angle A' defined between the axis of revolution 140, and a generatrix 142 of the fictitious conical surface 136, remains less than or equal to 70°, and even more preferably less than or equal to 45°. Furthermore, as can be seen from the above, the fictitious conical surface 136 is oriented so as to open outwards from the packaging, here axially

[0124] 15 towards the outside of the packaging. The tip of this conical surface 136, formed by its apex 138, is therefore preferentially oriented towards the axial center of the packaging.

[0125] To further enhance the reliability of the temperature determination of the seal 30, at least part of the sensor 30 is traversed by a fictitious axis passing through a point

[0126] 20 of the joint, and parallel to the axial direction 4. Typically, this fictitious axis corresponds to the aforementioned axis of revolution 140, passing through the center of the joint 22b in half-section.

[0127] In these scenarios, the small axial distance between the seal 22b and the sensor 30, along with the material continuity within the cover body 18a, combined with the good conductivity of the steel forming this body, significantly reduces uncertainties in determining the seal temperature. Indeed, numerical simulations have also demonstrated a small difference between the actual temperature of a point of interest on the sealing gasket 22b and the measurement point on the third surface S3 of the cover body 18a.

[0128] Figure 6 represents a second preferred embodiment of the invention, in which the

[0129] 30 Sealing joint 22b is arranged radially between the first corresponding SI surface 43359 AP

[0130] 13 here to a circumferential surface of the lid body 18a oriented radially outwards, and the second surface S2, corresponding here to an inner lateral surface of the recess 32 in the axial end portion 24. The surface S2 is oriented radially inwards.

[0131] 5 In this second preferred embodiment, the temperature sensor 30 is also fixed externally to the packaging body 8, and more precisely to the fourth surface S4 corresponding to the external surface, oriented radially outwards, of the annular axial end portion 24 of the side packaging body 14. Preferably, the sensor 30 is arranged directly or substantially directly above the seal 22b in the radial direction 6, in a manner identical or similar to that shown with reference to Figure 2. According to the alternative in Figure 7, only the position of the temperature sensor 30 changes; it is mounted on the third surface S3, corresponding here to the external surface of the lid body 18a, oriented axially in the opposite direction to that of the containment chamber 10. Here again, preferably, the sensor 30 is arranged directly or

[0132] 15 substantially at the right of the joint 22b in the axial direction 4, in a manner identical or analogous to that shown with reference to figure 5.

[0133] Figure 8 shows a third preferred embodiment of the invention, similar to the first preferred embodiment. The only change is the absence of the axial recess on the annular axial end portion 24 of the lateral packaging body 14.

[0134] On the alternative in Figure 9, the only change is that the sensor is mounted on the third surface S3 which here corresponds to the circumferential surface of the lid body 18a, oriented radially outwards and which is no longer radially covered by the axial end portion 24 of the lateral packaging body 14.

[0135] 25 In the other alternative shown in Figure 10, the design is analogous to that of Figures 5 and 7, with the temperature sensor 30 mounted on the third surface S3, corresponding here to the external surface of the lid body 18a, oriented axially in the opposite direction to that of the containment chamber 10. 43359 AP

[0136] 14

[0137] Figure 11 represents a fourth preferred embodiment of the invention, in which the temperature is determined for the sealing gasket 22a of Figure 1, axially constrained between the plug 18b of the cover 18a, and the cover body 18a.

[0138] The packaging element adjacent to the lid body 18a, as defined previously

[0139] 5 indicated, is therefore the plug 18b for sealing the passage orifice 20, made through the cover body 18a.

[0140] It is noted that the external surface of the lid body 18a has an axial recess 58, for housing at least in part the sealing plug 18b, belonging to the lid 18.

[0141] 10 In this fourth preferred embodiment, the first surface SI corresponds to an axial bottom surface of the recess 58, while the second surface S2, which is axially opposite it, corresponds to an internal surface of the sealing plug 18b, oriented axially towards the containment chamber.

[0142] Furthermore, the temperature sensor 30 is mounted on the third surface S3, which here corresponds to an external surface of the sealing plug 18b, oriented axially opposite the containment chamber. The sensor 30 is also located directly above or nearly directly above the seal 22a, in the axial direction 4, as described above.

[0143] With the packaging design described above, the invention enables the implementation of a method for determining the temperature of either of the two seals.

[0144] 20 sealing 22a, 22b, or both, during the storage of radioactive materials, using the temperature sensor 30 arranged externally to the packaging body 8.

[0145] Referring to Figure 12, which illustrates the sequence of this process, the first step A1 consists of measuring a reference temperature using the temperature sensor 30 located near the seal 22a, 22b, external to the packaging body 8. Next, step A2 consists of applying a correction to the reference temperature to determine a temperature for the seal 22a, 22b. This correction is determined beforehand by numerical simulations, which make it possible to determine the temperature difference between a point of interest on the seal and the point on the packaging body where the temperature is measured by the sensor 30. This correction can depend on a large number of factors.

[0146] 30 parameters such as the precise geometry and materials of the body components 43359 AP

[0147] 15 of packaging 8, or the thermal power profile of the contents. It can take the form of a temperature difference value to be added to the measured value, or result from the application of a more complex, predefined mathematical formula.

[0148] With reference to Figure 1, an electronic device 60 can be associated with the packaging, in order to

[0149] 5 to jointly form an assembly 62. The electronic device 60 is then configured to generate, from a reference temperature measured and delivered by the temperature sensor 30, a temperature of the sealing joint, by applying the aforementioned correction to this reference temperature.

[0150] At step A3, the determined temperature of the seal can be stored and / or analyzed.

[0151] 10. In particular, this allows for the assessment of the seal's aging status, taking into account the storage time already endured. By thus exploiting the actual available margins for the seal's durability over time, through the measurement of an external temperature closely correlated with the actual temperature of the seal, the storage time of radioactive materials can be advantageously extended. For example, a gain of around ten degrees in the seal temperature can lead to an increase in storage time of several years, or even several decades.

[0152] To monitor the temperature of the sealing gasket 22a, 22b during the storage period of the packaging, the determination procedure just described can be repeated.

[0153] 20 In this regard, it is noted that once loaded and positioned vertically in a stable environment such as a storage hall, the packaging adopts a steady-state thermal state that evolves very slowly, following the gradual reduction of the residual power of the radioactive materials. Due to this slow evolution, measurements, even taken on the outer surface at a distance from the seal, allow for reliable and efficient monitoring of the temperature evolution of this seal.

[0154] Of course, various modifications can be made by a person skilled in the art to the invention just described, by way of non-limiting examples only. In particular, the characteristics of the different preferred embodiments described above, and of their alternatives, can be combined.

[0155] 30

Claims

1. 43359 AP 16 DEMANDS 1. Packaging (1) for the storage of radioactive materials (12), the packaging comprising a packaging body (8) defining a containment enclosure (10) for the materials 5 radioactive, the packaging body comprising a side packaging body (14) extending around a longitudinal axis (2) of the packaging, as well as a base (16) and a removable lid (18) spaced apart along the longitudinal axis (2), the removable lid comprising a lid body (18a) fixed to an annular axial end portion (24) of the side packaging body (14), the packaging comprising a sealing gasket (22a, 22b) constrained between a first and a second facing surface (S1, S2) belonging to the packaging body (8), the first surface (S1) being a surface of the lid body (18a), and the second surface (S2) being a surface of a packaging element (18b, 24) adjacent to the lid body (18a), characterized in that the packaging also comprises a temperature sensor (30) 15 for determining a temperature of said sealing joint (22a, 22b), the sensor being mounted on a third or fourth external surface (S3, S4) of the packaging body (8), the third surface (S3) being an external surface of the cover (18), and the fourth surface (S4) being an external surface of the annular axial end portion (24) of the side packaging body (14).

2. Packaging according to claim 1, characterized in that at least a part of the sensor (30) is arranged in a space (34, 134) internally delimited by a fictitious conical surface of revolution (36, 136) oriented so as to open towards the outside of the packaging, and having the following characteristics: - a vertex (38, 138) corresponding to a point on the joint; 25 - an axis of revolution (40, 140) parallel to a radial direction (6) or a longitudinal direction (4) of the packaging; and - an angle (A, A'), defined between the axis of revolution (40, 140) and a generatrix (42, 142) of the fictitious conical surface (36, 136), less than or equal to 70°, and preferably less than or equal to 45°. 43359 AP 17 3. Packaging according to any one of the preceding claims, characterized in that at least a part of the sensor (30) is traversed by a fictitious axis (40) passing through a point of the joint, and parallel to the radial direction (6) or to the axial direction (4).

4. Packaging according to any one of the preceding claims, characterized in that 5 the sensor (30) is arranged axially beyond the containment enclosure (10), in the direction of the lid.

5. Packaging according to any one of the preceding claims, characterized in that the temperature sensor (30) is a non-contact sensor, for example taking the form of an infrared temperature sensor. 10 6. Packaging according to any one of the preceding claims, characterized in that said packaging element adjacent to the lid body (18a) is the annular axial end portion (24) of the side packaging body (14).

7. Packaging according to claim 6, characterized in that the annular axial end portion (24) of the side packaging body (14) defines an axial recess (32) for housing at least part of the lid body (18a), and in that the first and second facing surfaces (SI, S2) are respectively an internal surface of the lid body (18a), and a bottom axial surface of the recess (32).

8. Packaging according to any one of claims 1 to 5, characterized in that said packaging element adjacent to the lid body (18a) is an element of the lid, 20 corresponding to a plug (18b) for sealing a passage orifice (20) through the cover body (18a), for example a drainage orifice, and in that the first and second surfaces (SI, S2) opposite are respectively an external surface of the cover body (18a), and an internal surface of the sealing plug (18b).

9. Packaging according to claim 8, characterized in that the external surface of the lid body has an axial recess (58) for housing at least in part the sealing plug (18b), and in that the first surface (SI) is the axial bottom surface of the recess (58).

10. Packaging according to any one of the preceding claims, characterized in that 30 that it includes a protective cowling (28) against an air accident, the cowling covering 43359 AP 18 at least in part, axially and radially, the annular axial end portion (24) of the lateral packaging body (14).

11. Assembly (62) comprising a package (1) according to any one of the preceding claims, and an electronic device (60) configured to generate, from 5 of a reference temperature measured and delivered by said temperature sensor (30), a temperature of the sealing gasket, by applying a correction to the reference temperature.

12. A method for determining the temperature of the sealing gasket (22a, 22b) in a package (1) according to any one of claims 1 to 10, characterized in that it 10 includes the following steps: - measurement of a reference temperature using the temperature sensor (30); - application of a correction to the reference temperature, in order to determine a seal temperature.

13. Method for monitoring the temperature of the sealing gasket (22a, 22b) in a package (1) according to any one of claims 1 to 10, preferably during a storage period of this package, the monitoring method being carried out by a reiterative implementation of the method for determining the temperature of the sealing gasket according to claim 10.

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