FLEXIBLE IRRADIATION FACILITY

Abstract

An irradiation facility for a nuclear reactor, a method of removing thermal heat from an irradiated object and adjusting an energy distribution/neutron/gamma-ray flux ratio of irradiation, and a product obtainable by the method.

Claims

1. A moveable irradiation facility for a nuclear reactor comprising: a holder, at least one opening for receiving a sample, and an adaptable filter, wherein the adaptable filter comprises at least one of a band-gap filter, a blocking medium of certain energies, a gamma radiation generator, and combinations thereof, wherein the adaptable filter is for or has at least one of shielding the sample against at least one specific species of neutrons, shielding the sample against at least one species of beta rays, shielding the sample against at least one species of gamma-rays, at least one energy band pass filter for neutrons, at least one energy band pass filter for beta rays, at least one energy band pass filter for gamma rays, and generating of a specific species of gamma-radiation, and wherein a band pass energy of the filter is selected from the group consisting of 0-0.5 keV, 0.5-5 keV, 10-30 keV, 100-200 keV, 250-500 keV, and 0.6-5 MeV, and combinations thereof, and the species is at least one of beta rays, gamma rays, and neutrons, and combinations thereof.

2. The irradiation facility according to claim 1, wherein the adaptable filter comprises at least one sheet, wherein the at least one sheet are placed behind one another.

3. The irradiation facility according to claim 2, wherein each sheet individually has a thickness, a composition, and an effective thickness, selected for at least one of absorbing at least one specific species of neutrons, absorbing at least one specific species of gamma-rays, absorbing at least one specific species of beta rays, absorbing a pre-determined fraction of said aforementioned specific species, and generating a pre-determined fraction of a specific species of gamma-radiation.

4. The irradiation facility according to claim 1, wherein the filter or at least parts thereof are removable.

5. The irradiation facility according to claim 2, wherein the sheet material is selected from the group consisting of Pb, Cd, Ni, Sc, Fe+Cr, Fe+Al+S, and Si+Ti.

6. The irradiation facility according to claim 1, wherein the filter comprises empty modules, wherein empty modules are filled with an inert material.

7. The irradiation facility according to claim 1, further comprising at least one slot for receiving a shield.

8. The irradiation facility according to claim 1, wherein an aluminium alloy is used for construction and cladding of at least one shield.

9. A method of at least one of removing thermal heat from an irradiated object, adjusting an energy distribution, adjusting a neutron ray intensity, and adjusting a gamma-ray intensity, the method comprising the steps of: providing a radiation source for emitting radiation, and shielding an irradiated object with an irradiation facility according to claim 1.

10. The method according to claim 9, wherein at least one of the following occur: thermal neutrons are absorbed, neutrons with a specific energy distribution are absorbed, gamma rays with a specific energy distribution are absorbed, beta rays with a specific energy distribution are absorbed, and gamma-rays with a specific energy distribution are created.

11. The method according to claim 9, wherein excess heat in the object is removed by an external means.

12. The use of an irradiation facility according to claim 1, for one or more of the groups consisting of manipulating an energy distribution of radiation species, absorbing neutrons with an energy of less than 5 eV, generating epithermal and fast neutrons, generating high energy gamma-radiation, and generating low energy gamma-radiation.

13. A product obtained by the method according to claim 9, wherein the product is selected from the group consisting of .sup.166Ho-isotope comprising organic molecules, .sup.99Mo-isotope comprising organic molecules, and .sup.177+177mLu in an organometallic molecule, and having a specific activity of more than 100 GBq/g isotope.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0041] The present invention relates in a first aspect to a reactor assembly.

[0042] The present filter is capable of or has at least one of shielding the sample against at least one specific species of neutrons, shielding the sample against at least one species of beta rays, shielding the sample against at least one species of gamma-rays, having at least one energy band pass filter for neutrons, at least one energy band pass filter for beta rays, at least one energy band pass filter for gamma rays, and generating of a specific species of gamma-radiation.

[0043] In an example of the present facility the adaptable filter comprises at least one sheet, wherein the at least one sheets are placed behind one and another. Therewith shielding can be adapted easily, such as by combining various sheets having various, and typically different, properties.

[0044] In an example of the present facility each sheet has a thickness, a composition, and an effective thickness. These may be selected independently per sheet, and may be selected in view of a combinatorial effect thereof. The parameters are selected for at least one of absorbing at least one specific species of neutrons, absorbing at least one species of gamma-rays, absorbing at least one species of beta rays, absorbing a pre-determined fraction of said aforementioned specific species, and generating a pre-determined fraction of a specific species of gamma-radiation. To give an example thereof, various filters may allow passage of a certain neutron energy, may block all entering gamma rays, and generate specific gamma rays. Such allows for a large degree of freedom in composing a filter.

[0045] In an example of the present facility the filter or at least parts thereof are removable. If remove a part of the filter can be left empty (or open) or can be replaceable by another filter element. So for a given experiment/irradiation a suitable filter can be composed.

[0046] In an example of the present facility a band pass energy of the filter is selected from 0-0.5 keV, 0.5-5 keV, 10-30 keV, 100-200 keV, 250-500 keV, and 0.6-5 MeV, and combinations thereof, the combinations then relating to different species. Likewise the filter may be adapted to certain specific species or combination thereof, the species being at least one of beta rays, gamma rays, and neutrons. In an example a certain energy range of neutrons may be passed through, and likewise a certain energy range of gamma rays.

[0047] When referring to an energy or energy distribution such is typically qualified by an average, and an energy range.

[0048] In an example of the present facility sheet material is selected from Pb, Cd, Ni, Sc, Fe+Cr, Fe+Al+S, and Si+Ti. Pb is found to block significantly all gamma rays, if thick enough. Cd allows passage of <0.5 keV neutrons, Sc allows passage of [0.5 keV; 5 keV] neutrons, Fe+Al+S allows passage of [10 keV; 30 keV] neutrons, Si+Ti allows passage of [0.5 keV; 5 keV] neutrons, and Ni, Fe and Cr allow generation of >8.9 MeV gamma rays.

[0049] In an example of the present facility the filter comprises empty modules, wherein empty modules are filled with an inert material, such as a gas, such as nitrogen. As such the empty slots/sheets do not interfere.

[0050] In an example the present facility comprises at least one slot for receiving a shield; as such the shield may be removed and entered easily. The facility optionally comprises as facilitating means guides for loading and unloading.

[0051] In an example of the present facility an aluminium alloy is used for construction and cladding of at least one shield. The aluminium alloy provides a long durable material for use under the relatively harsh conditions and hardly interferes with irradiation of the sample.

[0052] In a second aspect the present invention relates to a method of the present facility according to claim 11. Therein at least one of thermal heat is removed from an irradiated object, an energy distribution is adjusted, a neutron ray intensity is adjusted, and a gamma-ray intensity is adjusted. The method comprises the steps of providing a radiation source for emitting radiation, such as a nuclear reactor, and shielding an irradiated object with a irradiation facility according to any of the preceding claims. It is noted that an irradiation of an object typically generates heat, which may need to be removed (e.g. from an inside) thereof. The energy distribution applied to the object, typically a sample, may have an optimal energy distribution, and likewise composition of species, which may be pre-determined and typically is pre-determined. In view of this optimal distribution the present filter may be used to shield the object accordingly. The object is typically introduced into the present facility.

[0053] In an example of the present method at least one of thermal neutrons are absorbed, neutrons with a specific energy distribution are absorbed, gamma rays with a specific energy distribution are absorbed, beta rays with a specific energy distribution are absorbed, and gamma-rays with a specific energy distribution are created, such as having an energy >8.9 MeV.

[0054] In an example of the present method excess heat is in the object is removed by an external means, such as a cooling loop, such as a water cooler. Despite removing unwanted species, e.g. in terms of energy distribution, still some heat may be generated in the object. The excess heat may be removed, thereby reducing damage, improving yield, etc.

[0055] In a third aspect the present invention relates to a use according to claim 14, for manipulating an energy distribution of radiation species, such as neutrons, or gamma-rays.

[0056] In an example the present use is for absorbing neutrons with an energy of less than 5 eV, such as less than 1 eV. A similar use is envisaged for β-rays and γ-rays, albeit with different energy levels.

[0057] In an example the present use is for generating high energy gamma-radiation, such as having an energy of >8.9 MeV. The present use may also be for generating low energy gamma-radiation, such as having an energy of <1.2 MeV.

[0058] In a fourth aspect the present invention relates to a product obtained by the present method. The product may be used in medicine, in (radio-) therapy, in (radio-) diagnosis, in cancer therapy, in biology, such as for irradiation of cells, in chemistry, and in material science.

[0059] In an example the present product is selected from .sup.166Ho-isotope comprising organic molecules (such as organic polymers, such as poly lactic acid), .sup.99Mo-isotope comprising organic molecules, .sup.177+177mLu in an organometallic molecule. These products can easily be identified.

[0060] In an example the present product has a specific activity of more than 100 GBq/g isotope, preferably more than 125 GBq/g isotope, more preferably more than 150 GBq/g isotope, even more preferably more than 200 GBq/g isotope, such as more than 250 GBq/g isotope. Such a product distinguishes itself over the prior art in the specific activity, which activity is relatively easy to determine.

[0061] The present product may be used for diagnosis, therapy, generation of radiation, subtle treatment, imaging, generating soft beta's, for liver related purposes, etc. In said products radiation damage and/or radiological decomposition and/or thermal decomposition of the product is at least reduced by a factor 5-10 compared to prior art techniques, as a consequence of use of the present facility.

[0062] It is noted that the term “substantial” is intended to indicate that within a given accuracy, such as measurement, manufacturing, etc. elements are e.g. in line, etc.

[0063] The one or more of the above examples and embodiments may be combined, falling within the scope of the invention.

Examples

[0064] The invention is further detailed by the accompanying FIGURES, which are exemplary and explanatory of nature and are not limiting the scope of the invention. To the person skilled in the art it may be clear that many variants, being obvious or not, may be conceivable falling within the scope of protection, defined by the present claims.

[0065] A prototype facility has been built to reduce a gamma-ray flux and to reduce the radiation damage. It was observed that the solubility of an irradiated Molybdenum containing organic compound reduces by a factor of 6 when compared to irradiation without shielding. The lower the solubility, the lower the radiation damage, hence the damage was reduced significantly.

[0066] It has been found that .sup.166Ho packed in poly(L-lactic acid microspheres is produced at a high specific activity (e.g., >100 GBq/g .sup.166Ho). This seems not possible without gamma-ray shielding and target cooling.

[0067] The present substantial reduction of radiation damage of e.g. Mo-containing organic compounds will boost further development of the production of carrier-free .sup.99Mo, separated by recoil from neutron activated .sup.98Mo. Such is considered an inexpensive alternative to the production of .sup.99Mo by fission of (low enriched) uranium.

[0068] Similarly, present invention provides a higher specific activity of .sup.166Ho in poly-lactic acid containing microspheres, which will widen the use of these compounds in e.g. cancer therapy.

SUMMARY OF FIGURE

[0069] The invention although described in detailed explanatory context may be best understood in conjunction with the accompanying FIGURES.

[0070] FIG. 1 shows an example of the present facility.

DETAILED DESCRIPTION OF THE FIGURE

[0071] FIG. 1 shows an example of the present facility 100. Therein various sheets 21 are placed in the facility, whereas some empty slots 30 are visible. The sheets can be introduced and removed by making use of the guides. Each sheet may comprise (one or more of) various materials of varying thickness, in order to shield a sample or object to be irradiated. The sample is placed in the opening 10. The whole facility 100 and parts thereof can be moved.