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Particles containing alpha (¦Á) nuclides have been found in sediments in the circular water of reactor no. 2 of the Fukushima Daiichi Nuclear Power Plant (FDiNPS). Uranium (U), the main component of nuclear fuel, was analyzed by scanning electron microscope (SEM). Other ¦Á -nuclides (plutonium [Pu], americium [Am] and Curium [Cm]) were detected by ¦Á locus, and the morphology of ¦Á -nuclide particles was analyzed by SEM energy spectrum analysis (EDX). Several uranium particles ranging from submicron to several microns were found by scanning electron microscopy. These particles contain zirconium (Zr) and other elements that make up fuel cladding and structural materials. The 235U/238U isotope ratio in the solid fraction (including U particles) is consistent with the nuclear fuel found in reactor no. 2. This shows that uranium of the same fuel composition becomes finer. Particles containing nuclides identified by alpha trajectory analysis range in size from tens to hundreds of microns. EDX spectroscopic analysis shows that these particles mainly contain iron. Pu, Am and Cm are adsorbed on Fe particles due to the small amount of ¦Á -nuclide. This study elucidates differences in the dominant species of U and other alpha nuclides in the hydroponic deposits of the annular chamber of FDiNPS 2 reactor.
Tepco’s Fukushima Daiichi nuclear power plant (FDiNPS) was severely damaged by the March 11, 2011 earthquake and ensuing tsunami. At the time, units 1-3 of the six reactors were operating, and nuclear fuel in units 1-3 was damaged. Seawater and fresh water are injected to remove decay heat from nuclear fuel. The water remains in the basement of the building, where components of the nuclear fuel dissolve, creating a highly radioactive pool of water. Dead water contains radionuclides such as fission products and nuclear fuel actinides. Establish chemical treatment process to remove radionuclides, establish circulation engineering system, and recover cooling water for reuse. Since then, the amount of standing water has gradually decreased, but fine particles containing higher concentrations of alpha (¦Á) radionuclides have been found underground in the reactor buildings. Concentrations of alpha nuclides (102-105 Bq/L) in standing water, including sediment, are higher than in cooling water in downstream buildings. Radiated radionuclides, such as uranium (U) and plutonium (Pu), can cause severe internal exposure when they enter the body. ¦Á -nuclide is the main nuclide of fission products and should be strictly controlled compared with cesium (Cs)-137 and strontium (Sr)-90. Techniques for efficient removal of alpha nuclides from standing water must be developed. To this end, stagnant water was collected in the annular chamber in the basement of the reactor building of Unit 2, and the sediment in stagnant water was analyzed by radiochemical analysis. Samples containing mixed sludge components from the reactor building’s standing water confirmed the presence of alpha radionuclides. In order to continue treating stagnant water deep within reactor buildings in the future, a better understanding of the different types of alpha emitters is needed, particularly those containing particulate solids in stagnant water.
In this study, u radioactive particles associated with Cs particles (CsMPs) were detected outside the FDiNPS site, and their physical and chemical composition and morphology were analyzed 3, 4, 5, 6, 7, 8. Abe et al. collected CsMPs emitted by FDiNPS from the atmosphere and analyzed them using synchronous X-rays to detect U in CsMPs. Ochiai et al. detected hundreds of nanometers of U particles in CsMP by SEM-EDX analysis. The diffraction pattern of UO2 on magnetite was observed by transmission electron microscope, and the results reflected the composition of UO2. Similarly, diffraction patterns of UO2 and zirconia were obtained for mixed particles of Zr and U in CSMP. This indicates that U exists in CsMP in the form of UO2 and U-Zr nanocrystals. Kurihara et al. 8 analyzed the isotope ratios of 235U and 238U in CsMP by nanoscale sub-ion mass spectrometry and found that there was U in the fuel composition of reactor no. 2 in CsMP. Soil analyses 9, 10, 11, 12, 13, airborne particulates and CsMPs7 have also reported the release of fuel derived polyurethanes into the environment. The Buddha
Post time: May-24-2022
