Irradiation unit for the emission of nuclear radiation and corresponding method for the manufacture of an irradiation unit

Abstract

This irradiation unit (10) for the emission of nuclear radiation with an activity in the range of 9kCi to 15kCi comprises: - a cylindrical irradiation vessel (18) forming a closed internal volume (22); and - a plurality of irradiation sources (20) located within the closed internal volume (22); wherein: - the radiation sources (20) are essentially spherical; - the cylindrical irradiation vessel (18) is a single-walled vessel; and - the irradiation unit (10) further comprises a binder (21) arranged in the closed internal volume (22), wherein the irradiation sources (20) are embedded in the binder (21).

Description

[0001] The invention relates to the field of irradiation units for emitting nuclear radiation, for example, for use in sterilization systems. The invention also relates to a method for producing such an irradiation unit.

[0002] To create irradiation units, it is known to insert cylindrical irradiation sources into the core of a nuclear reactor to activate them. Reactors such as the CANDU reactor (CANada Deuterium Uranium) are commonly used for this purpose due to their high neutron flux.

[0003] Pressurised water reactors have a lower neutron flux than CANDU reactors, and the activation of known irradiation sources is not sufficient in this context to provide irradiation sources that meet the expectations of the irradiation unit market (i.e., approximately 12 kCi / irradiation unit).

[0004] Solutions have already been proposed to improve the activation of irradiation sources and thus provide more efficient irradiation units. One solution, for example, involves the use of zirconium layers between the layers to be activated during activation.

[0005] However, this solution is not entirely satisfactory because the Zr material must be removed before the activated material can be used in the irradiation unit.

[0006] US 2018 / 0 019 032 A1 and US 2022 / 0 212 878 A1 describe examples of irradiation units for emitting nuclear radiation.

[0007] An object of the invention is therefore to obtain an irradiation unit that is highly radioactive and can be easily manufactured without significant impact on the operation of nuclear reactors, for example a PWR (from the English abbreviation of the term Pressurized Water Reactor).

[0008] For this purpose, the invention relates to an irradiation unit for emitting nuclear radiation with an activity in the range of 9 kCi to 15 kCi, comprising: - a cylindrical irradiation vessel forming a closed internal volume; and - a plurality of radiation sources located in the closed internal volume;wherein: - the radiation sources are essentially spherical; - the cylindrical irradiation vessel is a single-walled vessel; and - the irradiation unit further comprises a binder arranged in the closed internal volume, wherein the irradiation sources are embedded in the binder.

[0009] The use of essentially spherical irradiation sources is particularly advantageous because such irradiation sources have a small operational footprint on the nuclear reactor in which the sources are irradiated, while they are particularly well activated due to the empty space between the sources. Furthermore, the use of a binder allows for sufficient safety even in a single-walled irradiation vessel, allowing the number of irradiation sources accommodated in the irradiation vessel to be increased and the activity of the irradiation unit to be increased.

[0010] According to a preferred embodiment, the irradiation unit according to the invention has one of the following features: - the irradiation sources are made of Co-60 or a Co-60 alloy; - an axial length of the irradiation vessel is between 200 mm and 500 mm and an inner diameter of the irradiation vessel is between 6 mm and 20 mm; - a radius of the radiation sources is less than 0.85 mm; - the binder is a resin; - the number of radiation sources comprises between 2000 and 6000 radiation sources; - the radiation sources fill between 30% and 70% of the volume of the closed internal volume; and - the irradiation sources of the plurality of irradiation sources consist of different materials and / or have different specific activities.

[0011] The invention also relates to a method for producing an irradiation unit as described above, the method comprising the following steps: - introducing a plurality of substantially spherical irradiation sources into at least one activation vessel to fill the activation vessel, the irradiation sources being in an inactivated state; - introducing at least one filled activation vessel into a nuclear reactor; - Activation of the radiation sources introduced into the at least one activation vessel; - removal of at least one activation vessel from the nuclear reactor; - transferring the activated irradiation sources from the at least one activation vessel into a container of a cylindrical irradiation vessel; - filling the container of the cylindrical irradiation vessel with a binder so that the irradiation sources are embedded in the binder; - Closing the container of the cylindrical irradiation vessel to form the irradiation unit.

[0012] According to a preferred embodiment, a plurality of activation vessels were used in the process steps.

[0013] Further features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings, which show a non-limiting example. In these figures: - Fig. 1 a cross-sectional view of an irradiation unit according to the invention; - Fig. 2 another cross-sectional view of the irradiation unit from Fig. 1, perpendicular to the cross-sectional view from Fig. 1; - Fig. 3 is a flowchart of the steps of the method for manufacturing an irradiation unit according to the invention; and - Fig. 4 a schematic representation of a step for the production of the irradiation unit, as well as such a unit which is located in an irradiation facility.

[0014] In Fig. 1 shows an irradiation unit 10 in cross section.

[0015] As explained later, such an irradiation unit 10 is manufactured using a nuclear reactor 12 and is configured, for example, for use in an irradiation facility 14 as shown in Fig. 4 shown.

[0016] The irradiation unit 10 is configured to emit nuclear radiation with an activity in the range of 9 kCi to 15 kCi. In other words, the irradiation unit 10 is radioactive and configured to have an activity in the range of 9 kCi to 15 kCi.

[0017] As in the Fig. 1 and Fig. 2, the irradiation unit 10 comprises a cylindrical irradiation vessel 18, a plurality of irradiation sources 20 and a binder 21.

[0018] The irradiation vessel 18 is essentially cylindrical and defines, for example, a longitudinal axis L-L'.

[0019] As in the Fig. 1 and Fig. 2, the irradiation vessel 18 forms a closed internal volume 22. The closed internal volume 22 is, for example, cylindrical.

[0020] The irradiation vessel 18 is single-walled, i.e., it comprises a single wall 24 that separates the closed internal volume 22 from an environment 26 of the irradiation unit 10.

[0021] The irradiation vessel 18 is formed from a radiation-permeable material and is made of stainless steel, for example.

[0022] An axial length L of the irradiation vessel 18, that is to say a length, for example an inner length, of the irradiation vessel 18 along the longitudinal axis L-L', is, for example, between 200 mm and 500 mm.

[0023] An inner diameter D of the irradiation vessel 18, i.e. a diameter of the inner volume 22, measured radially to the longitudinal axis LL', is, for example, between 6 mm and 20 mm.

[0024] As in Fig. As shown in Figure 2, the irradiation vessel 18 comprises, for example, a container 28 and a lid 30, wherein the container 28 and the lid 30 define the closed interior volume 22. The container 28 is single-walled and the lid 30 is also single-walled, for example.

[0025] The container 28 and the lid 30 are, for example, movable relative to each other. The container 28 and the lid 30 then form, for example, the irradiation vessel 18 when the lid 30 is attached to the container 28.

[0026] As in the Fig. 1 and Fig. 2, the plurality of irradiation sources 20 are located in the closed internal volume 22, that is, in the irradiation vessel 18.

[0027] The plurality of irradiation sources 18 comprises, for example, between 2000 and 6000 irradiation sources 20. In other words, between 2000 and 6000 irradiation sources 20 are located in the closed internal volume 22.

[0028] For example, the radius R of each irradiation source is less than 0.85 mm. For example, the radius of each irradiation source is identical.

[0029] The irradiation sources 20 emit radioactive radiation, particularly gamma radiation. In particular, the irradiation sources 20 are formed from a material that was activated in the nuclear power plant, as will be described in more detail later.

[0030] The radiation sources 20 are made, for example, of Co-60 or a Co-60 alloy. Alternatively, the radiation sources 20 are made of any other radioactive alloy.

[0031] In a particular embodiment, each irradiation source 20 of the plurality of irradiation sources is made of the same material and has, for example, a similar activity.

[0032] Alternatively, the irradiation sources 20 of the plurality of irradiation sources 20 are made of different materials and / or have a different specific activity.

[0033] The irradiation sources 20 fill, for example, between 30% and 70% of the volume of the closed interior volume 22. The remaining volume of the closed interior volume 22 is filled, for example, by the binding agent 21.

[0034] As in the Fig. 1 and Fig. As shown in Figure 2, the binder 21 is arranged in the closed interior volume 22. The binder 21 is arranged in particular in the closed interior space such that the radiation sources 20 are embedded in the binder 21.

[0035] The binding agent 21 is preferably radiation-permeable. The binding agent 21 is formed, for example, by the curing of a liquid material. The binding agent 21 is, for example, a resin.

[0036] On the right side of Fig. 4 shows an irradiation system 14 comprising an irradiation unit 10 as described above. The irradiation system 14 includes, for example, a receiving area 32 configured to receive the irradiation unit 10. The use of an irradiation unit 10 as described above is particularly advantageous due to the high activity of the irradiation unit 10, which makes the irradiation system 14 particularly efficient.

[0037] With reference to Fig. 3, a method 100 for producing the irradiation unit 10 is now described.

[0038] As already mentioned, an irradiation unit 10 as described above is manufactured using at least one nuclear reactor 12.

[0039] As in Fig. 4, the nuclear reactor 12 comprises, for example, at least one introduction channel 34. The nuclear reactor 12 is, for example, a pressurized water reactor (or PWR reactor, from the English abbreviation of the term Pressurized Water Reactor).

[0040] The introduction channel 34 is configured, for example, to accommodate at least one activation vessel 36.

[0041] In the example of Fig. 4, the nuclear reactor 12 includes two introduction channels 34, each of the introduction channels 34 configured to receive an activation vessel 36. In alternatives, multiple nuclear reactors 12 each include an introduction channel 34 configured to receive an activation vessel 36.

[0042] In an introduction step 110, a plurality of irradiation sources 20 are introduced into at least one activation vessel 36 in order to fill the activation vessel 36.

[0043] The activation vessel 36 is, for example, completely or partially filled with the plurality of irradiation sources 20. The activation vessel 36 is configured, for example, to accommodate 1000 to 4000 irradiation sources 20.

[0044] In the example of Fig. 4, the plurality of irradiation sources 20 are introduced into two different activation vessels 36 in the introduction step 110.

[0045] The irradiation sources 20 introduced into the activation vessel 36 are as described above, except that they are not yet activated. In other words, the irradiation sources 20 are in an inactivated state in the introduction step 110.

[0046] The non-activated radiation sources 20 consist, for example, of Co-59 or of a Co-59 alloy.

[0047] In an introduction step 120, the at least one filled activation vessel 36 is introduced into a nuclear reactor 12, for example into the core of a nuclear reactor. In the example of Fig. 4, the two filled activation vessels 36 are introduced into the reactor, for example each into a separate introduction channel 34.

[0048] In an activation step 130, the irradiation sources 20 arranged in the activation vessels 36 are activated. The irradiation sources 20 are activated by the radiation generated by the operation of the nuclear reactor 12.

[0049] For example, the irradiation sources 20 are fully activated after an irradiation period of between 2 and 6 years in the nuclear reactor.

[0050] In a removal step 140, the at least one activation vessel 36 is then removed from the nuclear power plant. In the example of Fig. 4 the two activation vessels 36 are removed.

[0051] The removal step 140 takes place when the irradiation sources 20 are activated.

[0052] In a transfer step 150, the activated irradiation sources 20 are transferred from the at least one activation vessel 36 into the container 28 of the cylindrical irradiation vessel 18. In the example of Fig. 4, the activated irradiation sources 20 are transferred from the two activation vessels 36 into the container 28 of the cylindrical irradiation vessel 18.

[0053] In a filling step 160, the container 28 of the cylindrical irradiation vessel 18 is filled with a binder. The container is filled such that the irradiation sources 20 are embedded in the binder.

[0054] The filling step 160 is followed, for example, by a solidification step (not shown) in which the binder 21 is solidified if necessary.

[0055] In a closing step 170, the container 28 containing the irradiation sources 20 and the binder 21 is closed, for example by placing the lid 30 on it. The container 28 thus closed then forms the irradiation unit 10.

[0056] As shown on the right in Fig. 4, such an irradiation unit 10 can then be introduced into an irradiation system 14, e.g. into the receiving area 32 of such an irradiation system 14, in particular for irradiating goods to be irradiated.

[0057] The use of spherical irradiation sources 20 is particularly advantageous because the inherent gaps when stacking such irradiation sources 20 lead to very good activation of these irradiation sources 20.

[0058] In addition, the use of a binder 21 enables the safe use of a single-walled irradiation vessel 18, which leads to an optimization of the usable space for the irradiation sources 20 and to a high performance of the irradiation unit 10.

[0059] The use of Co-60 or a Co-60 alloy for the irradiation sources is particularly advantageous for the emission of gamma rays used in the irradiation system 14. The dimensions of the irradiation vessel 18 also allow for easy integration into such irradiation systems 14.

[0060] The dimensions of the irradiation sources 20, their density in the internal volume 22 and their number are particularly advantageous for rapid and effective activation and for forming an effective irradiation unit 10.

[0061] The use of resin as a binder 21 ensures that the radioactive emission is not disturbed and at the same time enables easy manufacture of the irradiation unit 10.

[0062] The use of irradiation sources 20 made of different materials and / or with different specific activities ensures that the irradiation unit 10 is optimally adapted to the needs of the irradiation system 14 into which it is integrated.

Claims

[1] Irradiation unit (10) for emitting nuclear radiation with an activity in the range of 9 kCi to 15 kCi, comprising: - a cylindrical irradiation vessel (18) forming a closed internal volume (22); and - a plurality of irradiation sources (20) located in the closed internal volume (22); wherein: - the irradiation sources (20) are substantially spherical; - the cylindrical irradiation vessel (18) is a single-walled vessel; and - the irradiation unit (10) further comprises a binder (21) arranged in the closed internal volume (22), wherein the irradiation sources (20) are embedded in the binder (21). [2] Irradiation unit (10) according to claim 1, wherein the irradiation sources (20) consist of Co-60 or a Co-60 alloy. [3] Irradiation unit (10) according to claim 1 or 2, wherein an axial length of the irradiation vessel (18) is between 200 mm and 500 mm and wherein an inner diameter (D) of the irradiation vessel is between 6 mm and 20 mm. [4] Irradiation unit (10) according to one of the preceding claims, wherein a radius of the irradiation sources (20) is less than 0.85 mm. [5] Irradiation unit (10) according to one of the preceding claims, wherein the binder (21) is a resin. [6] Irradiation unit (10) according to one of the preceding claims, wherein the plurality of irradiation sources (20) comprises between 2000 and 6000 irradiation sources (20). [7] Irradiation unit (10) according to one of the preceding claims, wherein the irradiation sources (20) fill between 30% and 70% of the volume of the closed internal volume (22). [8] Irradiation unit (10) according to one of the preceding claims, wherein the irradiation sources (20) of the plurality of irradiation sources consist of different materials and / or have a different specific activity. [9] Method (100) for producing an irradiation unit (10) according to one of claims 1 to 8, the method comprising the following steps: - introducing (110) a plurality of substantially spherical irradiation sources (20) into at least one activation vessel (36) to fill the activation vessel (36), the irradiation sources (20) being in an inactivated state; - introducing (120) the at least one filled activation vessel (18) into a nuclear reactor (12); - activating (130) the irradiation sources (20) introduced into the at least one activation vessel (18); - removal (140) of the at least one activation vessel (18) from the nuclear reactor (12); - transferring (150) the activated irradiation sources (20) from the at least one activation vessel (36) into a container (28) of a cylindrical irradiation vessel (18); - filling (160) the container (28) of the cylindrical irradiation vessel (18) with a binder (21) so that the irradiation sources (20) are embedded in the binder (21); - closing (170) the container (28) of the cylindrical irradiation vessel (18) to form the irradiation unit (10). [10] A method (100) for manufacturing an irradiation unit according to claim 9, wherein a plurality of activation vessels (36) are used in the method steps.

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