Recent satellite imagery shows North Korea has made progress in construction of a light water nuclear reactor at the Yongbyon complex, a U.S. research institute said Thursday.

New developments in reactor construction over the past six months included the completion of two channels feeding water for its cooling system and the completion of the reactor's electric transformer yard, the North-monitoring website 38 North said.

Those developments indicate the reactor "is edging closer to becoming operational," it said.

38 North said, however, that it's difficult to predict when construction will finish and the reactor will be become operational. 

Aside from determining whether work has been finished inside the externally complete building, it still remains unclear whether the North has succeeded in fabricating the fuel assemblies necessary to power the reactor, it said.

Should the reactor become operational, it would be a significant development for North Korea because it could not only provide electricity for civilian purposes, but also produce fissile material for nuclear weapons, 38 North said. (Yonhap)