Abstract.  Two studies are included: tungsten accumulation in the main plasma and radiation processes of carbon ions in the detached plasma of JT-60U. [Tungsten] It has been found that tungsten accumulation becomes more significant with increasing plasma rotation velocity against the plasma current direction, where negative radial electric field is formed. The accumulation level does not depend on the tungsten generation flux, suggesting the transport plays a dominant role to determine the accumulation level. In a high density plasma at 63% of the Greenwald density, the tungsten accumulation levels decreased siginificantly, suggesting a shielding effect of the peripheral plasma. [Carbbon] The spectral lines of C²⁺ and C³⁺ emitted around the X-point in the detached plasma with MARFE are measured with a VUV spectrometer and a 2-dimensional visible spectrometer in order to compare the generation flux of C³⁺ ( ionization of C²⁺ and recombination of C⁴⁺ ) and the loss flux of C³⁺ ( ionization and recombination of C³⁺). It has been found that C³⁺ is produced by the volume recombination of C⁴⁺ and the ionization of C²⁺ comparably. In contrast, the volume recombination of C³⁺ is not detected, and the ionization flux of C³⁺ is less than 1% of the C³⁺ generation flux. Thus, the C³⁺ generation flux is higher by two orders of magnitude than the loss flux. This result suggests that another loss mechanism of C³⁺ such as transport loss from the X-point is significant.