WO2025196471A1 - Radioactive source adapted to be used in a gamma sterilization facility, gamma sterilization facility and method for manufacturing such a radioactive source - Google Patents

Radioactive source adapted to be used in a gamma sterilization facility, gamma sterilization facility and method for manufacturing such a radioactive source

Info

Publication number
WO2025196471A1
WO2025196471A1 PCT/IB2024/000156 IB2024000156W WO2025196471A1 WO 2025196471 A1 WO2025196471 A1 WO 2025196471A1 IB 2024000156 W IB2024000156 W IB 2024000156W WO 2025196471 A1 WO2025196471 A1 WO 2025196471A1
Authority
WO
WIPO (PCT)
Prior art keywords
capsules
radioactive source
top end
bottom end
longitudinal axis
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/IB2024/000156
Other languages
French (fr)
Inventor
Wolfgang Krause
Lars ACKERMANN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Areva NP SAS
Original Assignee
Framatome SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Framatome SA filed Critical Framatome SA
Priority to PCT/IB2024/000156 priority Critical patent/WO2025196471A1/en
Publication of WO2025196471A1 publication Critical patent/WO2025196471A1/en
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F5/00—Transportable or portable shielded containers
    • G21F5/015—Transportable or portable shielded containers for storing radioactive sources, e.g. source carriers for irradiation units; Radioisotope containers
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21G—CONVERSION OF CHEMICAL ELEMENTS; RADIOACTIVE SOURCES
    • G21G4/00—Radioactive sources
    • G21G4/04—Radioactive sources other than neutron sources
    • G21G4/06—Radioactive sources other than neutron sources characterised by constructional features
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21G—CONVERSION OF CHEMICAL ELEMENTS; RADIOACTIVE SOURCES
    • G21G4/00—Radioactive sources
    • G21G4/04—Radioactive sources other than neutron sources
    • G21G4/06—Radioactive sources other than neutron sources characterised by constructional features
    • G21G4/08—Radioactive sources other than neutron sources characterised by constructional features specially adapted for medical application
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1001—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy using radiation sources introduced into or applied onto the body; brachytherapy
    • A61N5/1007—Arrangements or means for the introduction of sources into the body

Definitions

  • Radioactive source adapted to be used in a gamma sterilization facility, gamma sterilization facility and method for manufacturing such a radioactive source
  • the present invention concerns radioactive source adapted to be used in a gamma sterilization facility.
  • the invention concerns a gamma sterilization facility comprising a radioactive source.
  • the present invention concerns a method for manufacturing a radioactive source for gamma sterilization facilities.
  • the present invention disclosure relates to the construction of Co-60 sources for gamma sterilization facilities.
  • the gamma sterilization facilities use Co-60 sources prepared in high flux reactors like the CANDU nuclear power reactor.
  • Light water reactors have a lower flux.
  • CN213642866 U discloses a radioactive source for a gyroscopic rotational radiosurgical treatment system, which comprises a cobalt-60 radioactive core body, an inner cladding, an intermediate cladding component and an outer cladding component.
  • CN1046811 16 A discloses a cobalt regulating rod and a cobalt rod cluster assembly for producing a medical high-specific-activity cobalt source.
  • US20110216868 A1 discloses an irradiation target plate comprising a plurality of holes for irradiation targets.
  • the object of the present invention disclosure is to provide radioactive, in particular Co-60, sources that may use radioactive material activated by light water reactors, which have a lower flux than CANDU reactors and that reach same source activation level for the sterilization facilities in the same low neutron flux environment in an appropriate activation time.
  • a radioactive source adapted to be used in a gamma sterilization facility, comprising: a top end and a bottom end, the top end and the bottom end being spaced apart from each other, wherein the radioactive source has a source longitudinal axis extending between the top end and the bottom end; an intermediate portion between the top end and the bottom end, wherein the intermediate portion comprises a plurality of capsules of radioactive activated material, wherein at least two of the plurality of capsules are arranged in a same intermediate plane being between the top end and the bottom end, wherein each capsule has a capsule longitudinal axis, wherein the at least two of the capsule longitudinal axes are in parallel to the source longitudinal axis, wherein - the capsules having shape of a portion of a circular cylinder, which is cut along the longitudinal axis; and/or
  • the intermediate portion comprises plurality of housings, wherein each housing includes at least one capsule in the same intermediate plane.
  • the intermediate portion in particular the common housing, has at least one extension in a cross section in the intermediate plane, which is greater than the minimal extension ;
  • the common housing has at least one extension in a cross section in the intermediate plane, which is between 1 and 3 times, in particular between 1 .5 and 3 times greater than the minimal extension;
  • the at least one extension is a first extension and/or a second extension corresponding to edges of a rectangle of a substantial rectangular shaped housing in the cross-section in the intermediate plane;
  • the top end in the top plane and the bottom end in the bottom plane are substantially cylindrically shaped, substantially oval shaped, or substantially rectangular shaped, in particular with curved edges, wherein, in particular the minimal extension corresponds to the shortest diameter in a cross-section in the top plane and/or bottom plane ;
  • the capsules are arranged in the radioactive source such that they form together a full circular cylinder;
  • the common housing is made of stainless steel and/or zirconium alloy;
  • the non-circular shape in the cross section in the intermediate plane is a substantially rectangular shape, having in particular indentations;
  • the source comprises a plurality of cylindrical housings being arranged in parallel to each other, wherein each housing includes at least one capsule;
  • the capsules comprise a cobalt core and a zirconium alloy sheath;
  • each of the capsule longitudinal axes is in parallel to the source longitudinal axis and/or each of the capsule longitudinal axes of capsules being arranged in the same intermediate plane is in parallel to the source longitudinal axis.
  • a gamma sterilization facility comprising a radioactive source according to an embodiment disclosed herein.
  • a method for manufacturing a radioactive source for gamma sterilization facilities comprising: providing a plurality of capsules with material to be activated; irradiating the capsule in a core of a nuclear reactor; assembling the plurality of capsules into a radioactive source having a top end and a bottom end the top end and the bottom end being spaced apart from each other, wherein the radioactive source has a source longitudinal axis extending between the top end and the bottom end, and an intermediate portion between the top end and the bottom end, wherein the intermediate portion comprises a plurality of capsules of a radioactive activated material, wherein at least two of the plurality of capsules are arranged in a same intermediate plane being between the top end and the bottom end, wherein each capsule has a capsule longitudinal axis, wherein the at least two of the capsule longitudinal axes are in parallel to the source longitudinal axis, wherein
  • the capsules having shape of a portion of a circular cylinder, which is cut along the longitudinal axis and/or;
  • the common housing has non-cylindrical shape in a crosssection in the intermediate plane and/or
  • the intermediate portion comprises plurality of housings, wherein each housing includes at least one capsule in the same intermediate plane.
  • the capsules are irradiated spaced apart from each other, in particular in the core of the nuclear reactor;
  • the nuclear reactor is a light water reactor
  • the radioactive source is a radioactive source according to one of the embodiments disclosed herein.
  • embodiments are also directed to methods by which the described radioactive source is used or by which the radioactive source apparatus is manufactured. It may include method steps for carrying out functions of the radioactive source or manufacturing parts of the radioactive source. The method steps may be performed by way of hardware components, firmware, software, a computer programmed by appropriate software, by any combination thereof or in any other manner.
  • Fig. 1 shows a source rack for a sterilization facility
  • Fig. 2 shows a side cross sectional view of a radioactive source
  • Fig. 3 shows a top cross sectional view of a first embodiment of a radioactive source
  • Fig. 4 shows a top cross sectional view of a second embodiment of a radioactive source
  • Fig. 5 shows a top cross sectional view of another embodiment of a radioactive source
  • Fig. 6a, 6b and 6c shows show schematically the top end of a radioactive source in a side view, a front view and a top view;
  • Fig. 7 shows a top cross sectional view of a further embodiment of a radioactive source
  • Fig. 8 shows a top cross sectional view of a further embodiment of a radioactive source
  • Fig. 9 shows a top cross sectional view of a further embodiment of a radioactive source.
  • Fig. 1 shows a source rack 1 for a sterilization facility.
  • radioactive sources 3 are arranged in the sterilization facilities are arranged in the source rack 1 .
  • the source rack is then inserted into a frame 5.
  • the frame including the source racks are moved out of a water pool, where they are safely stored during shutdown and maintenance period.
  • the radioactive sources in particular the Co-60 sources have a facility specific diameter and length.
  • the radioactive sources have to be qualified in accordance to IAEA safety Guide Nr 8.
  • a total activity inventory of a source is required, for example a cylindrical source with a total activity between 5 to 15 kCi.
  • the radioactive sources have to fit in existing source racks and be compatible with the most common sources.
  • compatible means, that there is always sufficient distance from one source to an adjacent source to ensure heat release, and/or that the source has compatible dimension to ensure the movement of the rack within the facility arrangement.
  • the source rack 1 comprises an upper rail 7 and a lower rail 9.
  • the upper and lower rail have respectively a U shape, where the openings of the upper rail 7 and the lower rail 9 are facing each other.
  • the opening of the rail has a width of about 0.5 to 1.5cm, for example about 1cm.
  • a plurality of sources 3 are inserted into the rail and are arranged in parallel to each other.
  • the sources 3 have a substantial cylindrical form and the longitudinal axis of the sources 3 are parallel to each other.
  • the radioactive sources 3 have typically a top end 10 and an opposite bottom end 12.
  • the source longitudinal axis extends between the top end and the bottom end.
  • the top end and the bottom end are adapted to fit into the upper rail 7 and the lower rail 9 respectively.
  • the top end 10 is matched to the U shape of the upper rail 7 and the bottom end 12 is matched to the U shape of the lower rail 9.
  • the top end and the bottom end 10, 12 are for example made of stainless steel.
  • the upper and lower rails 7, 9 are hold by side bars 14 spaced apart from each other. Thus, the radioactive sources 3 are not covered between the side bars and between the upper and lower rails 7, 9.
  • the radioactive sources 3 include a radioactive material, for example Cobalt, in particular Co-60.
  • Fig. 2 shows a side cross sectional view of a radioactive source
  • Fig. 3 shows a top cross sectional view of a first embodiment of a radioactive source 3a between the top end and the bottom end 12, in particular at an intermediate portion
  • Fig. 4 shows a top cross sectional view of a second embodiment of a radioactive source.
  • the side view corresponds essentially to the side view of Figure 2.
  • the embodiments of Fig. 3 and Fig. 4 are described together. Only the differences between the embodiments of Fig. 3 and Fig. 4 are highlighted below.
  • the top end has a minimal extension in a top plane and the bottom end has the minimal extension in a bottom plane, the top and bottom planes P, Q being parallel to each other and spaced apart from each other.
  • the top plane and the bottom plane are orthogonal to the longitudinal axis X.
  • the top and bottom planes define the cross section of the top end and the bottom end.
  • the top and bottom ends are substantially equal.
  • the minimal extension is the diameter in case of a circular cylindrical shape or may be the smaller diameter in case of a substantial oval shape.
  • top end and the bottom end 10, 12 are for example made of stainless steel and may include on the inside zirconium alloy.
  • the minimal extension is between 0.5 cm and 1 .5 cm, for example 1 cm, in case of a circular cylindrical shape.
  • the radioactive source 3 has a source longitudinal axis X extending between the top end 10 and the bottom end 12.
  • the length (or height) of the source is between 40 cm and 50 cm, for example 45cm.
  • the radioactive source comprises an intermediate portion 16 between the top end and the bottom end, in particular in direction of the longitudinal axis X.
  • the intermediate portion 16 has at least one extension in the cross section, in particular a diameter, at the intermediate plane I that is smaller than the minimal extension in the cross section , in particular the minimal diameter, of the top end and the bottom end. This enables to provide a predetermined distance between each intermediate portion 16.
  • the intermediate portion has a substantial constant diameter.
  • the diameter or extension(s) in a cross section in the intermediate plane of the intermediate portion is in particular measured in the central third of the radioactive source in direction of the longitudinal axis X.
  • the intermediate plane is parallel to the top plane and/or the bottom plane.
  • the intermediate plane is in the central third of the radioactive source in direction of the longitudinal axis X.
  • the intermediate portion has a length of about 35 cm to 45cm.
  • the radioactive sources are designed to be capsules having a shape of a portion of a circular cylinder 18, which is cut vertically, so that they can be combined to form a full circular cylinder.
  • the capsules 20 can have a half-cylindrical shape (as shown in Fig. 3) or the capsules 21 may have a quarter cylindrical shape (as shown in Fig. 4).
  • other portions of a circular cylinder are possible, for example a third of a circular cylindrical shape, when cut vertically, or a sixth of a circular cylindrical shape.
  • Each capsule has a cake shape.
  • the circular cylindrical shape of the combined capsules 20, 21 has a diameter of 5 to 10 mm.
  • the capsules comprise cobalt and have a zirconium alloy sheath or container.
  • the zirconium alloy sheath may comprise one or more cobalt bodies.
  • two or more zirconium capsules are arranged one above another.
  • a capsule has a length of about 15 to 25 cm.
  • the capsules 20, 21 having a shape of a portion of a circular cylinder are activated when they are separated from each other, for example in the core of a nuclear reactor. In such a case, they have a lower diameter during the activation.
  • the capsules are then arranged to form a full circular cylinder in the intermediate portion 16 of the radioactive source, in particular in a hollow circular cylindrical housing 22 of the intermediate portion 16 of the radioactive source.
  • the housing 22 is made of stainless steel and/or zirconium alloy. In other embodiments, even other materials may be used.
  • the housing 22 forms a common housing for the capsules 20, 21 in the same intermediate plane I.
  • the full circular cylinder of the combined capsules 20, 21 has the same longitudinal axis as the longitudinal axis X. In other embodiments, the circular cylinder has a longitudinal axis, which is parallel to the longitudinal axis X.
  • the longitudinal axes of the capsules 20, 21 is in parallel to the longitudinal axis of the full circular cylinder of the combined capsules 20, 21.
  • the longitudinal axes of the capsules 20, 21 is in parallel to the longitudinal axis of the housing 22.
  • the capsules 18, 20, 21 are stacked one upon the other in the hollow circular cylindrical housing 22, in particular to extend along the complete length or height of the circular housing 22.
  • two or more capsules are provided one above another along the intermediate portion.
  • a capsule has a length of about 15 to 25 cm.
  • the cobalt is provided within the capsules and the capsules are provided in the housings, there is a double wall encapsulation.
  • the contamination is reduced as the housing 22 was not in the nuclear reactor during the activation of the cobalt.
  • Fig. 5 shows a top cross sectional view of another embodiment of a radioactive source.
  • two adjacent radioactive sources are shown, which are arranged in parallel.
  • the dashed lines 30 correspond respectively to the circumference of the top end and the bottom end of the radioactive sources 32.
  • the top end and the bottom end may have also another form, as explained below with respect to Figure 6.
  • Each radioactive source 32 comprises in its intermediate portion a bundle of a plurality of hollow circular cylindrical housings 34.
  • the housings 34 are fixed to the bottom end and the top end at their respective ends.
  • each intermediate portion comprises a bundle of three housings 34. In other embodiments, the number may be two or even four.
  • the housings of the bundle of a plurality of hollow cylindrical housings are substantially equal.
  • the intermediate portion has a length of about 35 cm to 45cm.
  • the longitudinal axes of the housings 34 are spaced regularly around the longitudinal axis of the radioactive source 32.
  • the diameter of the housings 34 of the bundle of a plurality of housings 34 is smaller than the diameter of the top end and the bottom end in case that the top end and bottom and have a circular cylindrical shape.
  • the diameter of the hollow circular cylindrical housings 34 is between 0.6 and 0.9 times the diameter or the minimal extension of the top end and/or the bottom end.
  • the hollow cylindrical rods 34 are for example made of stainless steel and/or zirconium alloy. In other embodiments, even other materials may be used.
  • Cylindrical capsules 36 are arranged respectively in the hollow cylindrical housings 34.
  • the capsules 36 are stacked one upon the other in the hollow circular housings 34, in particular to extend along the complete length or height of the circular housings 34.
  • the housings 34 form a housing for the capsules 36.
  • cylindrical capsules 36 are smaller compared to the capsules as shown in Figure 1 or the full circular cylinders of the combined capsules 20, 21 in Figures 3 and 4.
  • the cylindrical capsules 36 are fitted into the housings 34.
  • the diameter of the cylindrical capsules 36 are slightly smaller than the diameter of the housings 34, in order to insert them therein.
  • the cylindrical capsules 36 are activated individually and inserted into the plurality of housings 34.
  • the cylindrical capsules contain for example Co-60.
  • three cylindrical capsules are arranged in the same intermediate plane. However, the number may be greater if more housings 34 are used.
  • the longitudinal axes of the capsules 36 is in parallel to the longitudinal axis of the housings 34.
  • a capsule has a length of about 15 to 25 cm.
  • the capsules have a diameter of 5 to 10 mm.
  • Fig. 6 shows an embodiment of the top end of a radioactive source.
  • Fig. 6a shows the top end, when inserted into the upper rail 7.
  • the top end as it can be seen from Fig. 6c does not have a circular cylindrical shape.
  • the lower end has the same form.
  • the top end has rather an oval shape and/or a rectangular shape with curved edges in the top plane and/or bottom plane.
  • the top end has a width W in a direction perpendicular of the upper rail 7 and a length in direction of the upper rail 7.
  • the width W is adjusted to the opening of the rail 7 and in particular corresponds substantially to the width of the opening of the rail.
  • the width W is between about 0.5 to 1 .5cm, for example about 1cm.
  • the length L extends in parallel to the rail and has a longer extension that the width, for example L>W.
  • the aspect ratio between the lengths and the width is between 1 .2 and 2.
  • the minimal extension corresponds to the shortest diameter in a cross-section in the top plane and/or the bottom plane, here for example the width W, which in particular corresponds substantially to the width of the opening of the rail 7.
  • Fig. 7 shows a top cross sectional view of a further embodiment of a radioactive source
  • the dashed lines 52 correspond respectively to the circumference of the top end and the bottom end of the radioactive source 50, in case of a circular cylindrical top end and bottom end.
  • the top end and the bottom end may have also another form, as explained above with respect to Figure 6.
  • the radioactive source 50 comprises in its intermediate portion a hollow housing 54.
  • the cross-section of the housing 54 is substantially rectangular shaped.
  • the housing is fixed to the bottom end and the top end at its respective ends.
  • the housing 54 is made of stainless steel and/ or zirconium alloy. In other embodiments, even other materials may be used.
  • the intermediate portion has a length of about 35 cm to 45cm.
  • the housing has a first extension and the second extension, the second extension being orthogonal to the first extension.
  • the first extension is greater than the second extension.
  • the first extension and the second extension corresponding to the edges, in particular the long and the short edge, of the rectangle of the substantial rectangular shaped housing 54 in a cross-section in the intermediate plane I.
  • At least the first extension is greater than the minimal extension of the top end and the bottom end.
  • at least the first extension of the housing 54 is between 1 and 3 times, in particular 1 .5 and 3 times the minimal extension or diameter of the top end and/or the bottom end, wherein, in particular, the second extension of the hollow housing 54 is between 1 and 3 times the minimal extension of the top end and/or the bottom end.
  • the housing 54 has a size in each horizontal dimension, which is greater than the minimal extension or diameter of the top end and the bottom end in the respective top and bottom planes (P,Q).
  • the housing 54 forms an irregularly formed housing. According to embodiments, the surface of the housing 54 be adapted to the need of fixing the capsules and/or increasing the surface for heat removal.
  • capsules 56 are shown, which are arranged in the same intermediate plane.
  • the capsules are arranged, in the cross section of the housing, in three parallel rows, the rows being orthogonal to the longitudinal axis of the capsules, orthogonal to the longitudinal axis of the intermediate portion, and/or orthogonal to the longitudinal axis X of the radioactive source.
  • the capsules 56 of adjacent rows are staggered with respect to each other.
  • the housing 54 forms a common housing for the capsules 56 in the same intermediate plane.
  • the capsules can be circular cylinders or portions of a circular cylinder, which is cut along their longitudinal axis, as shown with respect to Figures 2 and 3.
  • the longitudinal axes of the capsules 56 is in parallel to the longitudinal axis of the housing 54.
  • the housing 54 has indentations 57, which extend in longitudinal direction of the radioactive source and are groove shaped.
  • the indentations have a substantial U shape in a cross section in the intermediate plane.
  • the housing 54 forms receptacles 58 for the capsules 56, in particular the ones, which are located at the circumference.
  • the capsules 56 are stacked one upon the other in the housing 54, in particular to extend along the complete length or height of the housing 54.
  • a capsule has a length of about 15 to 25 cm.
  • the capsules have a diameter of 5 to 10 mm.
  • Fig. 8 shows a top cross sectional view of a further embodiment of a radioactive source 60.
  • the dashed lines 62 correspond respectively to the circumference of the top end and the bottom end of the radioactive source 60.
  • the top end and the bottom end may have also another form, as explained above with respect to Figure 6.
  • the radioactive source 60 comprises in its intermediate portion a housing 64.
  • the cross-section of the housing is substantially rectangular shaped.
  • the housing 64 is fixed to the bottom end and the top end at its respective ends.
  • the housing 64 is made of stainless steel and/ or zirconium alloy. In other embodiments, even other materials may be used.
  • the intermediate portion has a length of about 35 cm to 45 cm.
  • the housing has a first extension and the second extension, the second extension being orthogonal to the first extension.
  • the first extension is greater than the second extension.
  • the first extension and the second extension corresponding to the edges, in particular the long and the short edge, of the rectangle of the substantial rectangular shaped housing 64 in a cross-section in the intermediate plane I.
  • At least the first extension is greater than the minimal extension of the top end and the bottom end.
  • at least the first extension of the housing 64 is between 1 and 3 times, in particular 1 .5 and 3 times the minimal extension or diameter of the top end and/or the bottom end, wherein, in particular, the second extension of the hollow housing 64 is between 1 and 3 times the minimal extension of the top end and/or the bottom end.
  • the housing 64 has a size in each horizontal dimension, which is greater than the minimal extension or diameter of the top end and the bottom end in the respective top and bottom planes (P,Q).
  • the housing 64 forms an irregularly formed housing.
  • eleven capsules 66 are shown, which are arranged in the same intermediate plane.
  • the capsules are arranged, in the cross section of the housing, in three parallel rows, the rows being orthogonal to the longitudinal axis of the capsules, orthogonal to the longitudinal axis of the intermediate portion, and/or orthogonal to the longitudinal axis X of the radioactive source.
  • the capsules 66 of adjacent rows are staggered with respect to each other.
  • the hollow housing 64 forms a common housing for the capsules 66 in the same intermediate plane.
  • the capsules can be circular cylinders or portions of a circular cylinder, which is cut along their longitudinal axis, as shown with respect to Figures 2 and 3.
  • the longitudinal axes of the capsules 66 is in parallel to the longitudinal axis of the housing 64, which is parallel to the longitudinal axis X of the radioactive source.
  • the housing 64 has indentations 67, which extend in longitudinal direction of the radioactive source and are groove shaped.
  • the indentations have a substantial V shape in a cross section in the intermediate plane.
  • the housing 64 forms receptacles 68 for the capsules 66, in particular the ones, which are located at the circumference.
  • the form of the housing enables a surface increase for an improved heat transfer.
  • the capsules 66 are stacked one upon the other in the housing 64, in particular to extend along the complete length or height of the housing 64.
  • a capsule has a length of about 15 to 25 cm.
  • the circular cylindrical shape of the capsules 66 has a diameter of 5 to 10 mm.
  • each of the capsules 66 may have a cobalt core 66a and a zirconium alloy sheath 66b. This is only indicated for one of the capsules in Figs. 8 and 9, but also apply for the other capsules. This may also apply to the embodiment shown in Figures 1 to 7.
  • Fig. 9 shows a top cross sectional view of a further embodiment of a radioactive source 70.
  • the dashed lines 72 correspond respectively to the circumference of the top end and the bottom end of the radioactive source 70.
  • the top end and the bottom end may have also another form, as explained above with respect to Figure 6.
  • the radioactive source 70 comprises in its intermediate portion a housing 74.
  • the housing has a substantially rectangular shaped cross-section.
  • the housing 74 is fixed to the bottom end and the top end at its respective ends.
  • the housing 74 is made of stainless steel and/ or zirconium alloy. In other embodiments, even other materials may be used.
  • the intermediate portion has a length of about 35 cm to 45cm.
  • the housing has a first extension and the second extension, the second extension being orthogonal to the first extension.
  • the first extension is greater than the second extension.
  • the first extension and the second extension corresponding to the edges, in particular the long and the short edge, of the rectangle of the substantial rectangular shaped housing 74 in a cross-section in the intermediate plane I.
  • At least the first extension is greater than the minimal extension of the top end and the bottom end.
  • at least the first extension of the housing 74 is between 1 and 3 times, in particular 1 .5 and 3 times the minimal extension or diameter of the top end and/or the bottom end, wherein, in particular, the second extension of the hollow housing 74 is between 1 and 3 times the minimal extension of the top end and/or the bottom end.
  • the housing 74 has a size in each horizontal dimension, which is greater than the minimal extension or diameter of the top end and the bottom end in the respective top and bottom planes (P,Q).
  • the housing 74 forms an irregularly formed housing.
  • FIG 9 six capsules 76 are shown, which are arranged in the same intermediate plane.
  • the capsules 76 are arranged in a point symmetrical way.
  • the housing 74 forms a common housing for the capsules 76 in the same intermediate plane.
  • the capsules can be circular cylinders or portions of a circular cylinder, which is cut along their longitudinal axis, as shown in Fig. 9.
  • the capsules 76 have a semi circular cylindrical shape.
  • a quarter of a cylinder or a third of a cylinder are also possible as form for the capsules.
  • the longitudinal axes of the capsules 76 is in parallel to the longitudinal axis of the housing 74.
  • the longitudinal axes of the capsules 20, 21 is in parallel to the longitudinal axis of the full circular cylinder of the combined capsules, which are in particular parallel to the longitudinal axis of the radioactive source.
  • a flat surface in particular of the majority of the capsules, is directed towards housing 74.
  • a flat surface of the capsules is arranged in parallel to a wall of the housing 74.
  • the housing 74 has chamfered corners 77, which extend in longitudinal direction of the radioactive source 70.
  • the chamfered corners enable an increased heat transfer.
  • the capsules 76 are stacked one upon the other in the housing 74, in particular to extend along the complete length or height of the housing 74.
  • each of the capsules 76 may have a cobalt core 76a and a zirconium alloy sheath 76b.
  • the embodiments of the invention provide a higher mass of cobalt in the sources, in particular of Co-60, and thus a higher activity.
  • Gamma sterilization facility may comprise a radioactive source 3, 32, 40, 50, 60, 70 according to one of the embodiments disclosed herein.
  • radioactive source 3 32, 40, 50, 60, 70 according to one of the embodiments disclosed herein is used.
  • a plurality of capsules with material to be activated is provided.
  • the capsules may comprise cobalt, in particular inactive Co-59.
  • they may further comprise a zirconium alloy sheath covering the cobalt.
  • the capsules 20, 21 , 76 have shape of a portion of a circular cylinder, which is cut along the longitudinal axis, as explained above.
  • the capsules may have the form a circular cylinder.
  • the capsules are irradiated in a light water reactor, for example a pressurized water reactor or a boiling water reactor, for activating the material, in particular the cobalt.
  • a light water reactor for example a pressurized water reactor or a boiling water reactor
  • the capsules are placed into the core of a light water reactor.
  • the capsules are irradiated spaced apart from each other. Thus, they are exposed to more neutron flux.
  • the capsules are removed from the core of the light water reactor, for example after an operation cycle of the nuclear reactor.
  • the capsules are irradiated about 3 years.
  • the plurality of capsules 18, 20, 21 , 46, 56, 66, 76 are assembled into a radioactive source 3, 32, 40, 50, 60, 70 having a top end and a bottom end, the top end and the bottom end being spaced apart from each other, wherein the radioactive source has a source longitudinal axis X extending between the top end and the bottom end, and an intermediate portion between the top end and the bottom end, wherein the intermediate portion comprises a plurality of capsules 18, 20, 21 , 56, 66, 76 of a radioactive activated material, wherein at least two of the plurality of capsules are arranged in a same intermediate plane being between the top end and the bottom end, wherein each capsule has a capsule longitudinal axis, wherein the at least two of the capsule longitudinal axes are in parallel to the source longitudinal axis.
  • the capsules 20, 21 , 76 having shape of a portion of a circular cylinder, which is cut along the longitudinal axis; and/or at least two of the capsules in the same intermediate plane are arranged in a common housing 22, 54, 64, 74, wherein the common housing has non-cylindrical shape in a cross-section in the intermediate plane; and/or the intermediate portion comprises plurality of housings, wherein each housing includes at least one capsule in the same intermediate plane. .
  • the capsules are inserted into housings.
  • the radioactive source can be then used in a gamma sterilization facility.
  • the activation and source forms are optimized with the goal to reach same source activation levels as produced in a CANDU reactor and support the implementation in existing source racks and in mixture to sources available on the market.
  • this is obtained due to a decreased cylindrical diameters or parts of a cylinder causing increased activation levels as the self-shielding effects are reduced.
  • the sources according to Figures 1 to 9 have an activity of 5 to 15 kCi.
  • the present invention uses in addition to vertical stacking a process of horizontal stacking or recombination to increase the volume of the activated material, for example Co- 60.

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Abstract

The present invention relates to a Radioactive source (3, 32, 50, 60, 70) adapted to be used in a gamma sterilization facility, comprising: a top end (10) and a bottom end (12), the top end and the bottom end being spaced apart from each other, wherein the radioactive source has a source longitudinal axis (X) extending between the top end and the bottom end; an intermediate portion (16) between the top end and the bottom end, wherein the intermediate portion comprises a plurality of capsules (18, 20, 21, 56, 66, 76) of radioactive activated material, wherein at least two of the plurality of capsules are arranged in a same intermediate plane being between the top end and the bottom end, wherein each capsule has a capsule longitudinal axis, wherein the at least two of the capsule longitudinal axes are in parallel to the source longitudinal axis, wherein - the capsules (20, 21, 76) having shape of a portion of a circular cylinder, which is cut along the longitudinal axis; and/or - at least two of the capsules in the same intermediate plane are arranged in a common housing (22, 54, 64, 74), wherein the common housing has non-cylindrical shape in a cross- section in the intermediate plane; and/or- the intermediate portion comprises plurality of housings, wherein each housing includes at least one capsule in the same intermediate plane.

Description

Radioactive source adapted to be used in a gamma sterilization facility, gamma sterilization facility and method for manufacturing such a radioactive source
The present invention concerns radioactive source adapted to be used in a gamma sterilization facility.
Further, the invention concerns a gamma sterilization facility comprising a radioactive source.
Finally, the present invention concerns a method for manufacturing a radioactive source for gamma sterilization facilities.
The present invention disclosure relates to the construction of Co-60 sources for gamma sterilization facilities. Usually, the gamma sterilization facilities use Co-60 sources prepared in high flux reactors like the CANDU nuclear power reactor. Light water reactors have a lower flux.
CN213642866 U discloses a radioactive source for a gyroscopic rotational radiosurgical treatment system, which comprises a cobalt-60 radioactive core body, an inner cladding, an intermediate cladding component and an outer cladding component.
CN1046811 16 A discloses a cobalt regulating rod and a cobalt rod cluster assembly for producing a medical high-specific-activity cobalt source.
US20110216868 A1 discloses an irradiation target plate comprising a plurality of holes for irradiation targets.
The object of the present invention disclosure is to provide radioactive, in particular Co-60, sources that may use radioactive material activated by light water reactors, which have a lower flux than CANDU reactors and that reach same source activation level for the sterilization facilities in the same low neutron flux environment in an appropriate activation time.
According to one aspect, a radioactive source is provided adapted to be used in a gamma sterilization facility, comprising: a top end and a bottom end, the top end and the bottom end being spaced apart from each other, wherein the radioactive source has a source longitudinal axis extending between the top end and the bottom end; an intermediate portion between the top end and the bottom end, wherein the intermediate portion comprises a plurality of capsules of radioactive activated material, wherein at least two of the plurality of capsules are arranged in a same intermediate plane being between the top end and the bottom end, wherein each capsule has a capsule longitudinal axis, wherein the at least two of the capsule longitudinal axes are in parallel to the source longitudinal axis, wherein - the capsules having shape of a portion of a circular cylinder, which is cut along the longitudinal axis; and/or
- at least two of the capsules in the same intermediate plane are arranged in a common housing, wherein the housing has non-cylindrical shape in the intermediate plane and/or
- the intermediate portion comprises plurality of housings, wherein each housing includes at least one capsule in the same intermediate plane.
Further embodiments may relate to one or more of the following features, which may be combined in any technical feasible combination:
- the top end having a minimal extension in cross-section in a top plane and the bottom end having the minimal extension in a cross-section in a bottom plane, wherein the intermediate portion, in particular the common housing, has at least one extension in a cross section in the intermediate plane, which is greater than the minimal extension ; the common housing has at least one extension in a cross section in the intermediate plane, which is between 1 and 3 times, in particular between 1 .5 and 3 times greater than the minimal extension;
- the at least one extension is a first extension and/or a second extension corresponding to edges of a rectangle of a substantial rectangular shaped housing in the cross-section in the intermediate plane; the top end in the top plane and the bottom end in the bottom plane are substantially cylindrically shaped, substantially oval shaped, or substantially rectangular shaped, in particular with curved edges, wherein, in particular the minimal extension corresponds to the shortest diameter in a cross-section in the top plane and/or bottom plane ;
- the capsules are arranged in the radioactive source such that they form together a full circular cylinder; the common housing is made of stainless steel and/or zirconium alloy;
- the non-circular shape in the cross section in the intermediate plane is a substantially rectangular shape, having in particular indentations;
- the source comprises a plurality of cylindrical housings being arranged in parallel to each other, wherein each housing includes at least one capsule;
- the capsules comprise a cobalt core and a zirconium alloy sheath;
- the radioactive activated material is cobalt; and/or - each of the capsule longitudinal axes is in parallel to the source longitudinal axis and/or each of the capsule longitudinal axes of capsules being arranged in the same intermediate plane is in parallel to the source longitudinal axis.
According to another aspect, a gamma sterilization facility comprising a radioactive source according to an embodiment disclosed herein.
According to another aspect, a method for manufacturing a radioactive source for gamma sterilization facilities is provided comprising: providing a plurality of capsules with material to be activated; irradiating the capsule in a core of a nuclear reactor; assembling the plurality of capsules into a radioactive source having a top end and a bottom end the top end and the bottom end being spaced apart from each other, wherein the radioactive source has a source longitudinal axis extending between the top end and the bottom end, and an intermediate portion between the top end and the bottom end, wherein the intermediate portion comprises a plurality of capsules of a radioactive activated material, wherein at least two of the plurality of capsules are arranged in a same intermediate plane being between the top end and the bottom end, wherein each capsule has a capsule longitudinal axis, wherein the at least two of the capsule longitudinal axes are in parallel to the source longitudinal axis, wherein
- the capsules having shape of a portion of a circular cylinder, which is cut along the longitudinal axis and/or;
- at least two of the capsules in the same intermediate plane are arranged in a common housing, wherein the common housing has non-cylindrical shape in a crosssection in the intermediate plane and/or
- the intermediate portion comprises plurality of housings, wherein each housing includes at least one capsule in the same intermediate plane.
Further embodiments may relate to one or more of the following features, which may be combined in any technical feasible combination:
- the capsules are irradiated spaced apart from each other, in particular in the core of the nuclear reactor;
- the nuclear reactor is a light water reactor; and/or
- the radioactive source is a radioactive source according to one of the embodiments disclosed herein.
Furthermore, embodiments are also directed to methods by which the described radioactive source is used or by which the radioactive source apparatus is manufactured. It may include method steps for carrying out functions of the radioactive source or manufacturing parts of the radioactive source. The method steps may be performed by way of hardware components, firmware, software, a computer programmed by appropriate software, by any combination thereof or in any other manner.
Further advantages, features, aspects and details are evident from the dependent claims, the description and the drawings.
The accompanying drawings relate to embodiments of the invention and are described in the following:
Fig. 1 shows a source rack for a sterilization facility;
Fig. 2 shows a side cross sectional view of a radioactive source;
Fig. 3 shows a top cross sectional view of a first embodiment of a radioactive source;
Fig. 4 shows a top cross sectional view of a second embodiment of a radioactive source;
Fig. 5 shows a top cross sectional view of another embodiment of a radioactive source;
Fig. 6a, 6b and 6c shows show schematically the top end of a radioactive source in a side view, a front view and a top view;
Fig. 7 shows a top cross sectional view of a further embodiment of a radioactive source;
Fig. 8 shows a top cross sectional view of a further embodiment of a radioactive source; and
Fig. 9 shows a top cross sectional view of a further embodiment of a radioactive source.
Fig. 1 shows a source rack 1 for a sterilization facility. Typically, radioactive sources 3 are arranged in the sterilization facilities are arranged in the source rack 1 . The source rack is then inserted into a frame 5. During operation in a sterilization facility the frame including the source racks are moved out of a water pool, where they are safely stored during shutdown and maintenance period.
In the following, the term “upper” and “lower” refers to the drawings and the arrangement shown in particular in Figures 1 and 2.
Usually, the radioactive sources, in particular the Co-60 sources have a facility specific diameter and length. The radioactive sources have to be qualified in accordance to IAEA safety Guide Nr 8. For an effective use a total activity inventory of a source is required, for example a cylindrical source with a total activity between 5 to 15 kCi. The radioactive sources have to fit in existing source racks and be compatible with the most common sources. In some embodiment compatible means, that there is always sufficient distance from one source to an adjacent source to ensure heat release, and/or that the source has compatible dimension to ensure the movement of the rack within the facility arrangement.
The source rack 1 comprises an upper rail 7 and a lower rail 9. The upper and lower rail have respectively a U shape, where the openings of the upper rail 7 and the lower rail 9 are facing each other. The opening of the rail has a width of about 0.5 to 1.5cm, for example about 1cm.
As it can be seen from Figure 1 , a plurality of sources 3 are inserted into the rail and are arranged in parallel to each other. The sources 3 have a substantial cylindrical form and the longitudinal axis of the sources 3 are parallel to each other. The radioactive sources 3 have typically a top end 10 and an opposite bottom end 12. The source longitudinal axis extends between the top end and the bottom end. The top end and the bottom end are adapted to fit into the upper rail 7 and the lower rail 9 respectively. In other words, the top end 10 is matched to the U shape of the upper rail 7 and the bottom end 12 is matched to the U shape of the lower rail 9. The top end and the bottom end 10, 12 are for example made of stainless steel.
The upper and lower rails 7, 9 are hold by side bars 14 spaced apart from each other. Thus, the radioactive sources 3 are not covered between the side bars and between the upper and lower rails 7, 9.
The radioactive sources 3 include a radioactive material, for example Cobalt, in particular Co-60.
Fig. 2 shows a side cross sectional view of a radioactive source and Fig. 3 shows a top cross sectional view of a first embodiment of a radioactive source 3a between the top end and the bottom end 12, in particular at an intermediate portion. Fig. 4 shows a top cross sectional view of a second embodiment of a radioactive source. The side view corresponds essentially to the side view of Figure 2. The embodiments of Fig. 3 and Fig. 4 are described together. Only the differences between the embodiments of Fig. 3 and Fig. 4 are highlighted below.
The top end has a minimal extension in a top plane and the bottom end has the minimal extension in a bottom plane, the top and bottom planes P, Q being parallel to each other and spaced apart from each other. The top plane and the bottom plane are orthogonal to the longitudinal axis X. The top and bottom planes define the cross section of the top end and the bottom end. The top and bottom ends are substantially equal. The minimal extension is the diameter in case of a circular cylindrical shape or may be the smaller diameter in case of a substantial oval shape.
As stated above the top end and the bottom end 10, 12 are for example made of stainless steel and may include on the inside zirconium alloy. For example, the minimal extension is between 0.5 cm and 1 .5 cm, for example 1 cm, in case of a circular cylindrical shape.
The radioactive source 3 has a source longitudinal axis X extending between the top end 10 and the bottom end 12. For example the length (or height) of the source is between 40 cm and 50 cm, for example 45cm.
Further, the radioactive source comprises an intermediate portion 16 between the top end and the bottom end, in particular in direction of the longitudinal axis X.
The intermediate portion 16 has at least one extension in the cross section, in particular a diameter, at the intermediate plane I that is smaller than the minimal extension in the cross section , in particular the minimal diameter, of the top end and the bottom end. This enables to provide a predetermined distance between each intermediate portion 16. The intermediate portion has a substantial constant diameter. The diameter or extension(s) in a cross section in the intermediate plane of the intermediate portion is in particular measured in the central third of the radioactive source in direction of the longitudinal axis X.
According to embodiments, which may be combined with other embodiments disclosed herein, the intermediate plane is parallel to the top plane and/or the bottom plane. In an embodiment, the intermediate plane is in the central third of the radioactive source in direction of the longitudinal axis X.
The intermediate portion has a length of about 35 cm to 45cm.
The radioactive sources are designed to be capsules having a shape of a portion of a circular cylinder 18, which is cut vertically, so that they can be combined to form a full circular cylinder. For example, the capsules 20 can have a half-cylindrical shape (as shown in Fig. 3) or the capsules 21 may have a quarter cylindrical shape (as shown in Fig. 4). Also other portions of a circular cylinder are possible, for example a third of a circular cylindrical shape, when cut vertically, or a sixth of a circular cylindrical shape. Each capsule has a cake shape. The circular cylindrical shape of the combined capsules 20, 21 has a diameter of 5 to 10 mm.
The capsules comprise cobalt and have a zirconium alloy sheath or container. The zirconium alloy sheath may comprise one or more cobalt bodies. For example, two or more zirconium capsules are arranged one above another. For example, a capsule has a length of about 15 to 25 cm.
The capsules 20, 21 , having a shape of a portion of a circular cylinder are activated when they are separated from each other, for example in the core of a nuclear reactor. In such a case, they have a lower diameter during the activation. After activation, the capsules are then arranged to form a full circular cylinder in the intermediate portion 16 of the radioactive source, in particular in a hollow circular cylindrical housing 22 of the intermediate portion 16 of the radioactive source. The housing 22 is made of stainless steel and/or zirconium alloy. In other embodiments, even other materials may be used. The housing 22 forms a common housing for the capsules 20, 21 in the same intermediate plane I.
The full circular cylinder of the combined capsules 20, 21 has the same longitudinal axis as the longitudinal axis X. In other embodiments, the circular cylinder has a longitudinal axis, which is parallel to the longitudinal axis X. The longitudinal axes of the capsules 20, 21 is in parallel to the longitudinal axis of the full circular cylinder of the combined capsules 20, 21. The longitudinal axes of the capsules 20, 21 is in parallel to the longitudinal axis of the housing 22.
In the embodiment of Figure 3, two capsules are arranged in the same intermediate plane and in Figure 4, four capsules are arranged in the same intermediate plane.
According to an embodiment, the capsules 18, 20, 21 are stacked one upon the other in the hollow circular cylindrical housing 22, in particular to extend along the complete length or height of the circular housing 22. For example, two or more capsules are provided one above another along the intermediate portion. For example, a capsule has a length of about 15 to 25 cm.
As the cobalt is provided within the capsules and the capsules are provided in the housings, there is a double wall encapsulation. In particular, the contamination is reduced as the housing 22 was not in the nuclear reactor during the activation of the cobalt.
Fig. 5 shows a top cross sectional view of another embodiment of a radioactive source. In Fig. 5 two adjacent radioactive sources are shown, which are arranged in parallel.
The dashed lines 30 correspond respectively to the circumference of the top end and the bottom end of the radioactive sources 32. However, the top end and the bottom end may have also another form, as explained below with respect to Figure 6.
Each radioactive source 32 comprises in its intermediate portion a bundle of a plurality of hollow circular cylindrical housings 34. The housings 34 are fixed to the bottom end and the top end at their respective ends. For example, in Figure 5, each intermediate portion comprises a bundle of three housings 34. In other embodiments, the number may be two or even four. The housings of the bundle of a plurality of hollow cylindrical housings are substantially equal. The intermediate portion has a length of about 35 cm to 45cm.
The longitudinal axes of the housings 34 are spaced regularly around the longitudinal axis of the radioactive source 32. The diameter of the housings 34 of the bundle of a plurality of housings 34 is smaller than the diameter of the top end and the bottom end in case that the top end and bottom and have a circular cylindrical shape. For example, the diameter of the hollow circular cylindrical housings 34 is between 0.6 and 0.9 times the diameter or the minimal extension of the top end and/or the bottom end. The hollow cylindrical rods 34 are for example made of stainless steel and/or zirconium alloy. In other embodiments, even other materials may be used.
Cylindrical capsules 36 are arranged respectively in the hollow cylindrical housings 34. For example, the capsules 36 are stacked one upon the other in the hollow circular housings 34, in particular to extend along the complete length or height of the circular housings 34. The housings 34 form a housing for the capsules 36.
Here the cylindrical capsules 36 are smaller compared to the capsules as shown in Figure 1 or the full circular cylinders of the combined capsules 20, 21 in Figures 3 and 4. The cylindrical capsules 36 are fitted into the housings 34. In other words, the diameter of the cylindrical capsules 36 are slightly smaller than the diameter of the housings 34, in order to insert them therein.
The cylindrical capsules 36 are activated individually and inserted into the plurality of housings 34. The cylindrical capsules contain for example Co-60.
In the embodiment of Figure 5, three cylindrical capsules are arranged in the same intermediate plane. However, the number may be greater if more housings 34 are used. The longitudinal axes of the capsules 36 is in parallel to the longitudinal axis of the housings 34.
For example, 2 or more capsules are provided one above another along the intermediate portion. For example, a capsule has a length of about 15 to 25 cm. The capsules have a diameter of 5 to 10 mm. Fig. 6 shows an embodiment of the top end of a radioactive source. Fig. 6a shows the top end, when inserted into the upper rail 7. The top end, as it can be seen from Fig. 6c does not have a circular cylindrical shape. The lower end has the same form. The top end has rather an oval shape and/or a rectangular shape with curved edges in the top plane and/or bottom plane. The top end has a width W in a direction perpendicular of the upper rail 7 and a length in direction of the upper rail 7. The width W is adjusted to the opening of the rail 7 and in particular corresponds substantially to the width of the opening of the rail. For example, the width W is between about 0.5 to 1 .5cm, for example about 1cm.
The length L extends in parallel to the rail and has a longer extension that the width, for example L>W. For example, the aspect ratio between the lengths and the width is between 1 .2 and 2. Thus, a rotation of the source is inhibited.
In case that the top end and the bottom end have no circular cylindrical shape, the minimal extension corresponds to the shortest diameter in a cross-section in the top plane and/or the bottom plane, here for example the width W, which in particular corresponds substantially to the width of the opening of the rail 7. Fig. 7 shows a top cross sectional view of a further embodiment of a radioactive source
50.
The dashed lines 52 correspond respectively to the circumference of the top end and the bottom end of the radioactive source 50, in case of a circular cylindrical top end and bottom end. However, the top end and the bottom end may have also another form, as explained above with respect to Figure 6.
The radioactive source 50 comprises in its intermediate portion a hollow housing 54. The cross-section of the housing 54 is substantially rectangular shaped. The housing is fixed to the bottom end and the top end at its respective ends. The housing 54 is made of stainless steel and/ or zirconium alloy. In other embodiments, even other materials may be used. The intermediate portion has a length of about 35 cm to 45cm.
The housing has a first extension and the second extension, the second extension being orthogonal to the first extension. The first extension is greater than the second extension. The first extension and the second extension corresponding to the edges, in particular the long and the short edge, of the rectangle of the substantial rectangular shaped housing 54 in a cross-section in the intermediate plane I.
At least the first extension, in particular both the first and second extensions, is greater than the minimal extension of the top end and the bottom end. For example, at least the first extension of the housing 54 is between 1 and 3 times, in particular 1 .5 and 3 times the minimal extension or diameter of the top end and/or the bottom end, wherein, in particular, the second extension of the hollow housing 54 is between 1 and 3 times the minimal extension of the top end and/or the bottom end.
The housing 54 has a size in each horizontal dimension, which is greater than the minimal extension or diameter of the top end and the bottom end in the respective top and bottom planes (P,Q).
The housing 54 forms an irregularly formed housing. According to embodiments, the surface of the housing 54 be adapted to the need of fixing the capsules and/or increasing the surface for heat removal.
In Figure 7 eight capsules 56 are shown, which are arranged in the same intermediate plane. For example, the capsules are arranged, in the cross section of the housing, in three parallel rows, the rows being orthogonal to the longitudinal axis of the capsules, orthogonal to the longitudinal axis of the intermediate portion, and/or orthogonal to the longitudinal axis X of the radioactive source. The capsules 56 of adjacent rows are staggered with respect to each other. The housing 54 forms a common housing for the capsules 56 in the same intermediate plane. The capsules can be circular cylinders or portions of a circular cylinder, which is cut along their longitudinal axis, as shown with respect to Figures 2 and 3. The longitudinal axes of the capsules 56 is in parallel to the longitudinal axis of the housing 54.
The housing 54 has indentations 57, which extend in longitudinal direction of the radioactive source and are groove shaped. The indentations have a substantial U shape in a cross section in the intermediate plane. Thus, the housing 54 forms receptacles 58 for the capsules 56, in particular the ones, which are located at the circumference.
According to an embodiment, the capsules 56 are stacked one upon the other in the housing 54, in particular to extend along the complete length or height of the housing 54.
For example, two or more capsules are provided one above another along the intermediate portion. For example, a capsule has a length of about 15 to 25 cm. The capsules have a diameter of 5 to 10 mm.
Fig. 8 shows a top cross sectional view of a further embodiment of a radioactive source 60.
The dashed lines 62 correspond respectively to the circumference of the top end and the bottom end of the radioactive source 60. However, the top end and the bottom end may have also another form, as explained above with respect to Figure 6.
The radioactive source 60 comprises in its intermediate portion a housing 64. The cross-section of the housing is substantially rectangular shaped. The housing 64 is fixed to the bottom end and the top end at its respective ends. The housing 64 is made of stainless steel and/ or zirconium alloy. In other embodiments, even other materials may be used. The intermediate portion has a length of about 35 cm to 45 cm.
The housing has a first extension and the second extension, the second extension being orthogonal to the first extension. The first extension is greater than the second extension. The first extension and the second extension corresponding to the edges, in particular the long and the short edge, of the rectangle of the substantial rectangular shaped housing 64 in a cross-section in the intermediate plane I.
At least the first extension, in particular both the first and second extensions, is greater than the minimal extension of the top end and the bottom end. For example, at least the first extension of the housing 64 is between 1 and 3 times, in particular 1 .5 and 3 times the minimal extension or diameter of the top end and/or the bottom end, wherein, in particular, the second extension of the hollow housing 64 is between 1 and 3 times the minimal extension of the top end and/or the bottom end. The housing 64 has a size in each horizontal dimension, which is greater than the minimal extension or diameter of the top end and the bottom end in the respective top and bottom planes (P,Q).
The housing 64 forms an irregularly formed housing. In Figure 8 eleven capsules 66 are shown, which are arranged in the same intermediate plane. For example, the capsules are arranged, in the cross section of the housing, in three parallel rows, the rows being orthogonal to the longitudinal axis of the capsules, orthogonal to the longitudinal axis of the intermediate portion, and/or orthogonal to the longitudinal axis X of the radioactive source. The capsules 66 of adjacent rows are staggered with respect to each other. The hollow housing 64 forms a common housing for the capsules 66 in the same intermediate plane. The capsules can be circular cylinders or portions of a circular cylinder, which is cut along their longitudinal axis, as shown with respect to Figures 2 and 3. The longitudinal axes of the capsules 66 is in parallel to the longitudinal axis of the housing 64, which is parallel to the longitudinal axis X of the radioactive source.
The housing 64 has indentations 67, which extend in longitudinal direction of the radioactive source and are groove shaped. The indentations have a substantial V shape in a cross section in the intermediate plane. Thus, the housing 64 forms receptacles 68 for the capsules 66, in particular the ones, which are located at the circumference. The form of the housing enables a surface increase for an improved heat transfer.
According to an embodiment, the capsules 66 are stacked one upon the other in the housing 64, in particular to extend along the complete length or height of the housing 64.
For example, two or more capsules are provided one above another along the intermediate portion. For example, a capsule has a length of about 15 to 25 cm. The circular cylindrical shape of the capsules 66 has a diameter of 5 to 10 mm.
As shown in Figure 8, each of the capsules 66 may have a cobalt core 66a and a zirconium alloy sheath 66b. This is only indicated for one of the capsules in Figs. 8 and 9, but also apply for the other capsules. This may also apply to the embodiment shown in Figures 1 to 7.
Fig. 9 shows a top cross sectional view of a further embodiment of a radioactive source 70.
The dashed lines 72 correspond respectively to the circumference of the top end and the bottom end of the radioactive source 70. However, the top end and the bottom end may have also another form, as explained above with respect to Figure 6.
The radioactive source 70 comprises in its intermediate portion a housing 74. The housing has a substantially rectangular shaped cross-section. The housing 74 is fixed to the bottom end and the top end at its respective ends. The housing 74 is made of stainless steel and/ or zirconium alloy. In other embodiments, even other materials may be used. The intermediate portion has a length of about 35 cm to 45cm. The housing has a first extension and the second extension, the second extension being orthogonal to the first extension. The first extension is greater than the second extension. The first extension and the second extension corresponding to the edges, in particular the long and the short edge, of the rectangle of the substantial rectangular shaped housing 74 in a cross-section in the intermediate plane I.
At least the first extension, in particular both the first and second extensions, is greater than the minimal extension of the top end and the bottom end. For example, at least the first extension of the housing 74 is between 1 and 3 times, in particular 1 .5 and 3 times the minimal extension or diameter of the top end and/or the bottom end, wherein, in particular, the second extension of the hollow housing 74 is between 1 and 3 times the minimal extension of the top end and/or the bottom end.
The housing 74 has a size in each horizontal dimension, which is greater than the minimal extension or diameter of the top end and the bottom end in the respective top and bottom planes (P,Q).
The housing 74 forms an irregularly formed housing.
In Figure 9 six capsules 76 are shown, which are arranged in the same intermediate plane. In an embodiment, the capsules 76 are arranged in a point symmetrical way. The housing 74 forms a common housing for the capsules 76 in the same intermediate plane. The capsules can be circular cylinders or portions of a circular cylinder, which is cut along their longitudinal axis, as shown in Fig. 9. For example, the capsules 76 have a semi circular cylindrical shape. However also a quarter of a cylinder or a third of a cylinder are also possible as form for the capsules. The longitudinal axes of the capsules 76 is in parallel to the longitudinal axis of the housing 74. As for Figures 3 and 4 The longitudinal axes of the capsules 20, 21 is in parallel to the longitudinal axis of the full circular cylinder of the combined capsules, which are in particular parallel to the longitudinal axis of the radioactive source. In case of capsules having the form of a portion of a circular cylinder, in particular a form of a semi-circular cylinder, a flat surface, in particular of the majority of the capsules, is directed towards housing 74. For example, for a majority of the capsules, a flat surface of the capsules is arranged in parallel to a wall of the housing 74.
The housing 74 has chamfered corners 77, which extend in longitudinal direction of the radioactive source 70. The chamfered corners enable an increased heat transfer.
According to an embodiment, the capsules 76 are stacked one upon the other in the housing 74, in particular to extend along the complete length or height of the housing 74.
For example, two or more capsules are provided one above another along the intermediate portion. For example, a capsule has a length of about 15 to 25 cm. The circular cylindrical shape of two combined capsules 74 would have a diameter of 5 to 10 mm. As shown in Figure 9, each of the capsules 76 may have a cobalt core 76a and a zirconium alloy sheath 76b. The embodiments of the invention provide a higher mass of cobalt in the sources, in particular of Co-60, and thus a higher activity.
Gamma sterilization facility may comprise a radioactive source 3, 32, 40, 50, 60, 70 according to one of the embodiments disclosed herein.
In the following a method for manufacturing a radioactive source for gamma sterilization facilities is explained, where in particular a radioactive source 3, 32, 40, 50, 60, 70 according to one of the embodiments disclosed herein is used.
In a first step a plurality of capsules with material to be activated is provided. The capsules may comprise cobalt, in particular inactive Co-59. For example, they may further comprise a zirconium alloy sheath covering the cobalt. In some embodiments, the capsules 20, 21 , 76 have shape of a portion of a circular cylinder, which is cut along the longitudinal axis, as explained above. In other embodiments, the capsules may have the form a circular cylinder.
In a further step, the capsules are irradiated in a light water reactor, for example a pressurized water reactor or a boiling water reactor, for activating the material, in particular the cobalt. For example, for such a purpose they are placed into the core of a light water reactor. For example, the capsules are irradiated spaced apart from each other. Thus, they are exposed to more neutron flux.
Then, the capsules are removed from the core of the light water reactor, for example after an operation cycle of the nuclear reactor. In an embodiment, the capsules are irradiated about 3 years.
Subsequently, the plurality of capsules 18, 20, 21 , 46, 56, 66, 76 are assembled into a radioactive source 3, 32, 40, 50, 60, 70 having a top end and a bottom end, the top end and the bottom end being spaced apart from each other, wherein the radioactive source has a source longitudinal axis X extending between the top end and the bottom end, and an intermediate portion between the top end and the bottom end, wherein the intermediate portion comprises a plurality of capsules 18, 20, 21 , 56, 66, 76 of a radioactive activated material, wherein at least two of the plurality of capsules are arranged in a same intermediate plane being between the top end and the bottom end, wherein each capsule has a capsule longitudinal axis, wherein the at least two of the capsule longitudinal axes are in parallel to the source longitudinal axis. The capsules 20, 21 , 76 having shape of a portion of a circular cylinder, which is cut along the longitudinal axis; and/or at least two of the capsules in the same intermediate plane are arranged in a common housing 22, 54, 64, 74, wherein the common housing has non-cylindrical shape in a cross-section in the intermediate plane; and/or the intermediate portion comprises plurality of housings, wherein each housing includes at least one capsule in the same intermediate plane. . For example, the capsules are inserted into housings.
The radioactive source can be then used in a gamma sterilization facility.
According to the invention, is possible to obtain sources from a lower flux in a light water reactor without largely increasing the activation time or the influence on power production compared to a CANDU reactor. The activation and source forms are optimized with the goal to reach same source activation levels as produced in a CANDU reactor and support the implementation in existing source racks and in mixture to sources available on the market. In other embodiments, it is also possible to activate the capsules in a CANDU reactor.
According to the invention, this is obtained due to a decreased cylindrical diameters or parts of a cylinder causing increased activation levels as the self-shielding effects are reduced.
According to embodiments, the sources according to Figures 1 to 9 have an activity of 5 to 15 kCi.
The present invention uses in addition to vertical stacking a process of horizontal stacking or recombination to increase the volume of the activated material, for example Co- 60.
It is contemplated that elements of one embodiment may be advantageously utilized in other embodiments without further recitation.

Claims

1 . Radioactive source (3, 32, 50, 60, 70) adapted to be used in a gamma sterilization facility, comprising: a top end (10) and a bottom end (12), the top end and the bottom end being spaced apart from each other, wherein the radioactive source has a source longitudinal axis (X) extending between the top end and the bottom end; an intermediate portion (16) between the top end and the bottom end, wherein the intermediate portion comprises a plurality of capsules (18, 20, 21 , 56, 66, 76) of radioactive activated material, wherein at least two of the plurality of capsules are arranged in a same intermediate plane being between the top end and the bottom end, wherein each capsule has a capsule longitudinal axis, wherein the at least two of the capsule longitudinal axes are in parallel to the source longitudinal axis, characterized in that
- the capsules (20, 21 , 76) having shape of a portion of a circular cylinder, which is cut along the longitudinal axis; and/or
- at least two of the capsules in the same intermediate plane are arranged in a common housing (22, 54, 64, 74), wherein the common housing has non- cylindrical shape in a cross-section in the intermediate plane; and/or
- the intermediate portion comprises plurality of housings, wherein each housing includes at least one capsule in the same intermediate plane.
2. Radioactive source according to claim 1 , wherein the top end having a minimal extension in cross-section in a top plane (P) and the bottom end having the minimal extension in a cross-section in a bottom plane (Q), wherein the intermediate portion, in particular the common housing, has at least one extension in a cross section in the intermediate plane (I) a, which is greater than the minimal extension.
3. Radioactive source according to claim 2, wherein the common housing has at least one extension in a cross section in the intermediate plane (I), which is between 1 and 3 times, in particular between 1.5 and 3 times greater than the minimal extension.
4. Radioactive source according to claim 2 or 3, wherein the at least one extension is a first extension and/or a second extension corresponding to edges of a rectangle of a substantial rectangular shaped housing in the cross-section in the intermediate plane.
5. Radioactive source according to one of the preceding claims, wherein the top end (10) in the top plane and the bottom end (12) in the bottom plane are substantially cylindrically shaped, substantially oval shaped, or substantially rectangular shaped, in particular with curved edges, wherein, in particular the minimal extension corresponds to the shortest diameter in a cross-section in the top plane and/or bottom plane.
6. Radioactive source according to any one of the preceding claims, wherein the capsules (20, 21 ) are arranged in the radioactive source such that they form together a full circular cylinder.
7. Radioactive source according to one of the preceding claims, wherein the common housing (22, 44, 54, 64, 74) is made of stainless steel and/or zirconium alloy.
8. Radioactive source according to any one of the preceding claims, wherein the noncircular shape in the cross section in the intermediate plane is a substantially rectangular shape, having in particular indentations.
9. Radioactive source according to any one of the preceding claims, wherein the source comprises a plurality of cylindrical housings (34) being arranged in parallel to each other, wherein each housing includes at least one capsule.
10. Radioactive source according to one of the preceding claims, wherein the capsules comprise a cobalt core (66a, 76a) and a zirconium alloy sheath (66b, 76b).
11 . Radioactive source according to one of the preceding claims, wherein the radioactive activated material is cobalt.
12. Radioactive source according to one of the preceding claims, wherein each of the capsule longitudinal axes is in parallel to the source longitudinal axis and/or each of the capsule longitudinal axes of capsules being arranged in the same intermediate plane is in parallel to the source longitudinal axis (X).
13. Gamma sterilization facility comprising a radioactive source (3, 32, 40, 50, 60, 70) according to one of the preceding claims.
14. Method for manufacturing a radioactive source for gamma sterilization facilities, comprising: providing a plurality of capsules with material to be activated; irradiating the capsule in a core of a nuclear reactor; assembling the plurality of capsules into a radioactive source having a top end and a bottom end, the top end and the bottom end being spaced apart from each other, wherein the radioactive source has a source longitudinal axis (X) extending between the top end and the bottom end, and an intermediate portion between the top end and the bottom end, wherein the intermediate portion comprises a plurality of capsules (18, 20, 21 , 56, 66, 76) of a radioactive activated material, wherein at least two of the plurality of capsules are arranged in a same intermediate plane being between the top end and the bottom end, wherein each capsule has a capsule longitudinal axis, wherein the at least two of the capsule longitudinal axes are in parallel to the source longitudinal axis, wherein
- the capsules (20, 21 , 76) having shape of a portion of a circular cylinder, which is cut along the longitudinal axis; and/or
- at least two of the capsules in the same intermediate plane are arranged in a common housing (22, 54, 64, 74), wherein the common housing has non- cylindrical shape in a cross-section in the intermediate plane; and/or
- the intermediate portion comprises plurality of housings, wherein each housing includes at least one capsule in the same intermediate plane.
15. Method according to claim 14, wherein the capsules are irradiated spaced apart from each other, in particular in the core of the nuclear reactor.
16. Method according to claim 14 or 15, wherein the nuclear reactor is a light water reactor.
17. Method according to any one of the claims 14 to 16, wherein the radioactive source is a radioactive source according to one of the claims 1 to 13.
PCT/IB2024/000156 2024-03-22 2024-03-22 Radioactive source adapted to be used in a gamma sterilization facility, gamma sterilization facility and method for manufacturing such a radioactive source Pending WO2025196471A1 (en)

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6497647B1 (en) * 2001-07-18 2002-12-24 Ati Medical, Inc. Radiation and thermal energy source
US20030088145A1 (en) * 2001-07-18 2003-05-08 Scott William Tate Methods and devices for staged thermal and radiation therapy
EP1232771B1 (en) * 2001-02-15 2006-04-12 AEA Technology QSA GmbH Radioactive capsule seed
EP2121129B1 (en) * 2007-03-12 2011-01-12 Ben-Gurion University Of The Negev Research And Development Authority Thulium-containing low dose rate brachytherapy seed
US20110216868A1 (en) 2010-03-05 2011-09-08 Russell Ii William Earl Irradiation target positioning devices and methods of using the same
US8366598B2 (en) * 2005-07-22 2013-02-05 Biocompatibles Uk Limited Implants for use in brachytherapy and other radiation therapy that resist migration and rotation
CN104681116A (en) 2013-11-27 2015-06-03 上海核工程研究设计院 Cobalt regulating rod and cobalt rod cluster component used for producing medical cobalt source with high specific activity
CN213642866U (en) 2020-06-29 2021-07-09 北京三强核力辐射工程技术有限公司 High specific activity cobalt-60 radioactive source for gyro rotary type radiosurgery treatment system

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1232771B1 (en) * 2001-02-15 2006-04-12 AEA Technology QSA GmbH Radioactive capsule seed
US6497647B1 (en) * 2001-07-18 2002-12-24 Ati Medical, Inc. Radiation and thermal energy source
US20030088145A1 (en) * 2001-07-18 2003-05-08 Scott William Tate Methods and devices for staged thermal and radiation therapy
US8366598B2 (en) * 2005-07-22 2013-02-05 Biocompatibles Uk Limited Implants for use in brachytherapy and other radiation therapy that resist migration and rotation
EP2121129B1 (en) * 2007-03-12 2011-01-12 Ben-Gurion University Of The Negev Research And Development Authority Thulium-containing low dose rate brachytherapy seed
US20110216868A1 (en) 2010-03-05 2011-09-08 Russell Ii William Earl Irradiation target positioning devices and methods of using the same
CN104681116A (en) 2013-11-27 2015-06-03 上海核工程研究设计院 Cobalt regulating rod and cobalt rod cluster component used for producing medical cobalt source with high specific activity
CN213642866U (en) 2020-06-29 2021-07-09 北京三强核力辐射工程技术有限公司 High specific activity cobalt-60 radioactive source for gyro rotary type radiosurgery treatment system

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