WASHINGTON (AP) — North Korea is nearing completion of a light-water reactor that is primarily intended to generate electricity but which could add to concern over its nuclear program, a U.S.-based institute said Wednesday.

Satellite photos, the latest taken this month, show the North appears to be putting finishing external touches to the reactor at its Yongbyon nuclear complex, according to 38 North, the website of the U.S.-Korea Institute at Johns Hopkins School of Advanced International Studies in Washington. The reactor could potentially begin operation within a year or so, although considerable technical hurdles remain, 38 North says in its analysis.