Estimation of the Irradiated Graphite Surface Nanolayer Thickness Enriched by 14С Isotope

In the present paper we evaluate the thickness of the reactor graphite surface nanolayer enriched by
¹⁴
C isotope formed during reactor operation. This graphite surface
¹⁴
C enriched nanolayer is proposed to be removed using our new inert gas plasma decontamination technology. Surface decontamination of the nuclear power plant (NPP) constructions is provided by ion bombardment of the nano- and micro-sized radionuclides layer from the surface under treatment (cathode) and their diffusive transfer to collector plate (anode). There are many evidences that, e.g.
¹⁴
C is predominantly located on the surface of irradiated reactor graphite instead of the inside of the graphite bulk. It is due to
¹⁴
C main formation mechanism via effective neutron activation of the gaseous nitrogen, which is used as a coolant of the graphite piles. So, it is important to find N
2
molecules concentration and subsurface depth penetration inside of graphite samples. In this way plasma sputtering technology can significantly reduce the irradiated reactor graphite activity at the decommissioning of uranium-graphite reactors. Additionally, this technology can be used to separate various atomic species sputtered from the graphite sample (together with their radioactive isotopes) by their sedimentation temperature and to form nanosized layer enriched with preferred radionuclides of controlled thickness. It provides to obtain new materials like a beta-active "nano-micro-sandwich" with adjusted output fast electrons energy spectrum. It can be used in the nuclear medicine field and for a new type of the betavoltaic batteries.