Ion-beam irradiation and ²⁴⁴Cm-doping investigations of the radiation response of actinide-bearing crystalline waste forms

Abstract

Abstract

Investigation of Factors That Affect the Oxidation State of Ce in the Garnet-Type Structure

“…The high loading of U within this phase also suggests the potential of materials adopting the garnet-type structure to be nuclear waste forms. It is notable that garnet-type materials have been synthesized that contain a high concentration of U (∼30 wt % U). ,, A considerable amount of work has been completed to study the stability of actinides in garnet against radiation damage and corrosion resistance. ,− However, factors that affect the oxidation states in garnet-type oxides have not been addressed. The incorporation of radioactive actinides with varying oxidation states into nuclear wasteforms is also of importance. ,,− The substitution of U or Pu into garnet is complex because of the variable oxidation states of these elements, which can be studied by investigating Ce-containing garnet-type materials because Ce behaves in a manner similar to that of some actinide elements (e.g., Pu). , …”

Review of Rare-Earth Phosphate Materials for Nuclear Waste Sequestration Applications

“…The limitations faced by internal irradiation can be overcome using an external irradiation method in which the radiation events are simulated under laboratory conditions via high energy ion implantation. , In this method, the radiation conditions representing different time periods of HLW storage are attained in a very short time by irradiating a thin region of the monolithic wasteform (e.g., pellet) with high-energy ion beams (e.g., He 2+ , Ne + , Kr + , Au – ) of varying ion doses (i.e., number of ions/cm 2 ). , The externally irradiated solids are also nonradioactive, which therefore allows the use of different experimental techniques to characterize the ion-implanted solids . Since α-decay is the major decay pathway for actinides present in HLW, the wasteforms are irradiated with high-energy light (e.g., He 2+ ) and/or heavy (e.g., Pb + , Au – ) ions to simulate radiation effects due to α-particles and/or α-recoil atoms (i.e., daughter products), respectively …”

“…8 As a result, several studies have focused on investigating the radiation damage in solid wasteforms due to α-recoil atoms. 11 The extent of structural damage due to α-decay events varies depending on the dose (i.e., number of α-decay events per gram of actinide) and type of nuclear wasteform that is being studied. 7 Structurally, glass-based host matrices in which atoms are arranged in a random fashion are less affected by the atomic rearrangements that occur as a result of α-decay of actinides.…”

“…Compared to α-recoil, the β-recoil atom only generates about 0.1 atomic displacements per β-decay event . As a result, several studies have focused on investigating the radiation damage in solid wasteforms due to α-recoil atoms …”

The solubility, microstructure, and chemical durability of Ce‐doped YIG ceramics designed as actinide waste forms

“…Garnet ceramics also have excellent corrosion resistance. 12,19,28 In terms of radiation resistance, Livshits et al 29,30 found the garnet structure's radiation response is structurally constrained, which means that different compositions of garnet waste have similar radiation tolerance. Hence, garnet-based ceramics could be considered as a potential matrix for immobilizing HLW.…”