Spatially resolved analysis of plutonium isotopic signatures in environmental particle samples by laser ablation-MC-ICP-MS

Abstract

Laser ablation–multi-collector–inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) was optimized and investigated with respect to its performance for determining spatially resolved Pu isotopic signatures within radioactive fuel particle clusters. Fuel particles had been emitted from the Chernobyl nuclear power plant (ChNPP) where the 1986 accident occurred and were deposited in the surrounding soil, where weathering processes caused their transformation into radioactive clusters, so-called micro-samples. The size of the investigated micro-samples, which showed surface alpha activities below 40 mBq, ranged from about 200 to 1000 μm. Direct single static point ablations allowed to identify variations of Pu isotopic signatures not only between distinct fuel particle clusters but also within individual clusters. The resolution was limited to 100 to 120 μm as a result of the applied laser ablation spot sizes and the resolving power of the nuclear track radiography methodology that was applied for particle pre-selection. The determined 242Pu/239Pu and 240Pu/239Pu isotope ratios showed a variation from low to high Pu isotope ratios, ranging from 0.007(2) to 0.047(8) for 242Pu/239Pu and from 0.183(13) to 0.577(40) for 240Pu/239Pu. In contrast to other studies, the applied methodology allowed for the first time to display the Pu isotopic distribution in the Chernobyl fallout, which reflects the differences in the spent fuel composition over the reactor core. The measured Pu isotopic signatures are in good agreement with the expected Pu isotopic composition distribution that is typical for a RBMK-1000 reactor, indicating that the analyzed samples are originating from the ill-fated Chernobyl reactor. The average Pu isotope ratios [240Pu/239Pu = 0.388(86), 242Pu/239Pu = 0.028(11)] that were calculated from all investigated samples (n = 48) correspond well to previously published results of Pu analyses in contaminated samples from the vicinity of the Chernobyl NPP [e.g. 240Pu/239Pu = 0.394(2) and 242Pu/239Pu = 0.027(1); Nunnemann et al. (J Alloys Compd 271–273:45–48, 1998)].Graphical AbstractEvaluation of LA-MC-ICP-MS for spatially resolving ultra-trace Pu isotopic signatures stored in environmental radioactive particles, providing new insights into the Pu isotopic distribution of the Chernobyl reactor core at the time of the accident

Outstanding Thermal Conductivity of Single Atomic Layer Isotope-Modified Boron Nitride

“…According to secondary ion mass spectrometry (SIMS), these bulk crystals contained 99.2% and 99.9% 10 B and 11 B, respectively, close to the previously reported values [16]. Naturally occurring nitrogen has >99.6% 14 N, and thus can be considered as isotopically pure. The atomically thin 10 BN and 11 BN sheets were directly exfoliated and suspended over pre-fabricated micro-wells (3.8 µm in diameter) connected by narrow trenches (200 nm in width) in 80 nm gold-coated Si substrates (Au/Si) without polymer-assisted transfer process.…”

“…lattice parameter, disordering, elastic constant, vibration, band structure and transition, exciton, polariton dispersion and scattering. It, in turn, gives rise to appealing phenomena and applications, including the elevation of superconducting transition temperature, improvement in the lifetime of organic lightemitting diodes (OLED), optical fibers with higher speed, precise and accurate quantification of PHYSICAL REVIEW LETTERS 125, 085902 (2020) proteomes, and ultra-trace environmental analysis [13][14][15]. Naturally occurring BN ( Nat BN) contains a relatively high percentage of two stable boron isotopes: 19.9% 10 B and 80.1% 11 B; while carbon (C) normally consists of 98.9% 12 C and only 1.1% 13 C. The phonon energy, electronic bandgap, and electron density distribution of hBN could be varied by isotope engineering [16].…”

New horizons in microparticle forensics: Actinide imaging and detection of 238 Pu and 242m Am in hot particles

“…The analysis presented so far comprises of well-established routine techniques frequently reported before ( 14 ). In contrast to preceding work making use of subsequent destructive analysis techniques ( 22 , 23 ), the quasi-nondestructive static time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to determine the isotopic signature of the particle’s main elemental component, uranium. The four long-lived uranium isotopes 234–236, 238 U are well resolved in the mass spectrum shown in Fig.…”

Method for detecting and characterising actinide-bearing micro-particles in soils and sediment of the Fukushima Prefecture, Japan

“…9). Unfortunately, the very high uranium hydride formation rate ( UH + / U + = [12,38] or Thermal Ionisation Mass Spectrometry (TIMS) [39]. Fig.…”