Abstract Number: 238 Working Group: Instrumentation and Methods
Abstract After several years have passed from the Fukushima Daiichi Nuclear Power Plant accident, insoluble radioactive Cs-bearing particles have been found in some regions in Japan. These insoluble particles remain as a particle in human airways and continue emitting radiation. Therefore, there could be a concern about health effects. The particles are seemed to have present in contaminated nuclear reactors and the surrounding areas of F1NPP. To eliminate the hazard of the particles, it is necessary to understand and utilize the physical properties of the particles, which is not elucidated yet.
Because of the continuous emission of the electron beam, we hypothesized that the radioactive particles have specific electrostatic charging characteristics. In this study, we attempt to apply the technique of Kelvin Probe Force Microscopy (KPFM) to measure electrostatic charging characteristics of the particles.
KPFM is a method that enables imaging of nanometre-scale surface topography, and also the surface potential of a sample. KPFM scans a sample with an oscillating probe to detect interatomic force between the probe and the sample. Also, contact potential differences between the probe and sample are detected.
We used a glass substrate for the fixation and measurement medium of the radioactive particles, so we investigated whether the surface potential of the object on the glass substrate could be correctly measured by KPFM. We prepared a glass substrate with partially deposited of Au and biased arbitrary voltage to the Au part. When the bias voltage was changed by 0.1 V from 0.0 V to 0.4 V, the surface potential measured by the KPFM accurately represented the applied voltage.
Also, we measured radioactive Cs-bearing particle by KPFM, and there was the distribution of potential in the surface of the particle. The surface potential of the particle was approximately between +0.3 V and -0.3 V.