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JP-7856661-B2 - Removal of radioactive noble gases from gas volume

JP7856661B2JP 7856661 B2JP7856661 B2JP 7856661B2JP-7856661-B2

Inventors

  • マーマンズ，ジャスパー
  • マルテンス，ドミニク
  • スクリアロヴァ，ハンナ
  • ハイニッツ，ステファン
  • カーディナエルス，トーマス

Assignees

  • エスシーケー．シーイーエヌ

Dates

Publication Date
20260511
Application Date
20220207
Priority Date
20210205

Claims (15)

  1. A method for removing radioactive noble gases from a gas volume, a. A step of providing the gas volume such that the dew point of the gas volume at a gas temperature of 20°C is -20°C or lower , b. A step of passing the gas volume over a microporous molecular sieve bed (33) containing a transition metal placed on and/or within a microporous molecular sieve , thereby adsorbing the radioactive noble gas onto the bed (33), Includes, The aforementioned radioactive noble gas is Rn, A method characterized in that the microporous molecular sieve is ETS-10 or ZSM-5.
  2. The aforementioned microporous molecular sieve is containing transition metal nanoparticles and/or It is a transition metal exchange microporous molecular sieve. The method according to claim 1.
  3. The method according to any one of claims 1 to 2 , wherein the transition metal is selected from Group 10, Group 11 and Platinum Group.
  4. The method according to any one of claims 1 to 3 , wherein the gas volume includes a nonpolar carrier gas having a polarizability of 1,700 ų or less.
  5. The gas volume is 1.664 Å. 3 The method according to any one of claims 1 to 4, comprising a nonpolar carrier gas having the following polarizability.
  6. The method according to any one of claims 1 to 5 , wherein step a includes passing the gas volume over a moisture adsorption bed (32).
  7. Further step c. A step of regenerating the noble gas adsorption bed (33) and/or, if present, the moisture adsorption bed (32). The method according to any one of claims 1 to 6 , including the method described in any one of claims 1 to 6.
  8. The aforementioned step c is, Heating the noble gas adsorption bed (33) and/or, if present, the moisture adsorption bed (32), and/or The method according to claim 7, comprising flushing the noble gas adsorption bed (33) and/or, if present, the moisture adsorption bed (32) with a regenerating gas.
  9. A further step a' precedes step b, a': a step of removing substances toxic to the noble gas adsorption bed (33) and/or, if present, the moisture adsorption bed (32) from the gas volume. The method according to any one of claims 1 to 8 , including
  10. The adsorbed radioactive noble gas is It is held until it is effectively decayed, or Collected for further storage and/or use , The method according to any one of claims 1 to 9 .
  11. The method according to any one of claims 1 to 10 , carried out at room temperature.
  12. The method according to any one of claims 1 to 11 , carried out in a nuclear environment.
  13. A device (10) for removing radioactive noble gases from a gas volume, i. One or more moisture-absorbing beds (32), ii. One or more noble gas adsorption beds (33) of a microporous molecular sieve containing a transition metal, disposed on and/or within the microporous molecular sieve , Equipped with, The noble gas adsorption bed (33) has an input coupled to the output of the moisture adsorption bed (32), The aforementioned radioactive noble gas is Rn, The apparatus is characterized in that the microporous molecular sieve is ETS-10 or ZSM-5.
  14. iii. One or more regenerative gas sources (60) coupled to the noble gas adsorption bed (33) and optionally to the moisture adsorption bed (32) ; and/or iv. One or more scrubbers (31) for removing substances toxic to the noble gas adsorption bed (33) and/or the moisture adsorption bed (32) from the gas volume ; Furthermore, The scrubber (31) has an output coupled to the input of the noble gas adsorption bed (32), The apparatus (10) according to claim 13.
  15. A multilayer system for removing radioactive noble gases from a gas volume , wherein one or more layers comprise the apparatus (10) described in any one of claims 13 to 14.

Description

This invention relates to the removal of radioactive noble gases from a gas volume, and more particularly to such removal based on the adsorption of radioactive noble gases onto a microporous molecular sieve bed containing a transition metal. For example, in the production of 225Ac for medical use, it may be necessary to capture or remove radioactive noble gases from the medium (e.g., gas volume) by other means. 225Ac is a high-energy alpha-emitting radioisotope with potential therapeutic applications in targeted alpha therapy (TAT). TAT is a cancer treatment method based on high linear energy transfer (LET) of alpha particles, resulting in short-range, high-density ionization tracks within tissues. 225Ac is particularly well-suited as a TAT candidate due to its half-life (9.92 days), multiple alpha decays, and favorable chemical properties. Various studies have demonstrated the efficacy of 225Ac treatment for metastatic and terminal cancers. Currently, 225Ac is mainly obtained from 229Th generators from 233U stockpiles. Therefore, the supply of 225Ac is limited by the amount of 229Th available worldwide. However, current stockpiles are insufficient to meet the demand required for large-scale clinical trials and global cancer treatment. Accelerator-based production of 225Ac from 226Ra could be a solution to overcome this problem. One route is, for example, via the 226Ra (γ,n) 225Ra ( β- ) 225Ac reaction using bremsstrahlung photons from an electron accelerator, and another route is via the 226Ra (p,2n) 225Ac reaction using proton irradiation in a cyclotron. However, such production processes present significant technical challenges. One of the main problems with 225Ac production based on 226Ra precursors is the continuous emission of target radioactivity and radon (more specifically 222Rn ). Therefore, radon capture is crucial for safe operation, for example, to minimize uncontrolled emissions from ventilation systems. Furthermore, having a radon capture system that can be implemented in a hot cell environment capable of handling gram-level 226a operations would be industrially important. However, noble gases are nonpolar monatomic molecules with their outermost electron shells filled with eight valence electrons. Therefore, they typically do not chemically interact with other substances. As a result, noble gases are known to be difficult to capture or otherwise remove. One known method is based on the adsorption of noble gases onto an activated carbon bed. Generally, adsorption is the process by which atoms, molecules, or ions of a gas, liquid, or (dissolved) solid—i.e., adsorbents—diffuse onto the surface of an adsorbent—usually a solid—where they either form bonds (chemiadsorption) or are held by intermolecular forces (physicoadsorption). Therefore, adsorption is a surface phenomenon. Because they are chemically inert, noble gases experience physicoadsorption rather than chemiadsorption. Physicoadsorption relies on relatively weak forces (e.g., van der Waals forces), but its efficiency can usually be improved by lowering the temperature of the adsorbent. Consequently, the adsorption of noble gases such as Kr, Xe, and Rn is typically carried out in conventional techniques on activated carbon beds cooled to cryogenic temperatures. Based on literature from 1908 to 2002, a summary of radon adsorption results reported on activated carbon and under various conditions was prepared by Gaul (GAUL, Wayne C. The application of moment analysis to the dynamic adsorption of radon by activated carbon. University of South Carolina, 2004. PhD thissis.). However, this method has several challenges. For example, the activated carbon adsorption bed needs to be kept at extremely low temperatures (e.g., below 0°C, -50, -65, or -75°C), otherwise the adsorption coefficient k- of noble gases, and thus the retention time t-, will decrease significantly. Furthermore, even at extremely low temperatures, the adsorption coefficient k requires that the activated carbon bed be large enough to capture a meaningful amount of noble gases, especially when the bed is operated in continuous mode. Moreover, cooling systems operating at extremely low temperatures are susceptible to condensation and freezing in the pipes. Even if moisture traps are in place to protect the pipes, this can lead to gas flow being blocked by frozen water. Finally, large quantities of charcoal itself pose a high fire hazard. Therefore, in this field, better approaches for capturing or removing noble gases are still needed. The object of the present invention is to provide a good method for removing noble gases from a gas volume. A further object of the present invention is to provide an excellent device related thereto. This object is achieved by the method, apparatus, and system according to the present invention. An advantage of the embodiments of the present invention is that they can achieve effective adsorption of noble gases. An advantage of the embodiments of