According to South Korean reports, 3,000 volt high-tension wire was built around an artificial lake, which included an artificial island, and a large military force surrounded the region, which is isolated, like a nuclear facility. Excavation of this 400,000 cubic meter facility could accommodate a 200 megawatt-class graphite-moderated reactor.
On 23 October 1998 opposition lawmaker Rep. Kim Deog-ryong of the opposition Grand National Party [GNP] claimed that "Large-scale projects to build nuclear facilities are under way in Kumchang and Taechon, north of Yongbyon." He claimed that the Kumchang facility is presumed to include reactors and a reprocessing plant, which he said will be put into operation in four to six years. "The installations will be able to extract an amount of plutonium large enough to produce one nuclear weapon in six to 12 months after they start operations in 2002 or 2003.... North Korea will soon be able to produce a sufficient amount of plutonium for the manufacture of eight to 10 nuclear weapons every year." He said the participation of elite engineers, the installation of electric wiring and the construction of a water-storage dam for the reactors prove that they are nuclear facilities.
The United States has raised its concerns with the DPRK about this suspect underground site under construction, possibly intended to support nuclear activities contrary to the Agreed Framework. In March 1999, the United States reached agreement with the DPRK for visits by a team of US experts to the facility. In May 1999, a Department of State team visited the underground facility at Kumchang-ni. The team was permitted to conduct all activities previously agreed to help remove suspicions about the site.
On 25 June 1999 the US Government Report on the US Visit to the Site at Kumchang-ni concluded that excavation of the complex, as currently configured, was almost complete but a great deal of additional finishing work remained to be done with almost all of the tunnels still bare rock. Given the current size and configuration of the underground area, the Report found that the site is unsuitable for the installation of a plutonium production reactor, especially a graphite-moderated reactor of the type North Korea has built at Yongbyon. The site is also not well designed for a reprocessing plant. The US government concluded that the site at Kumchang-ni does not contain a plutonium production reactor or a reprocessing plant either completed or under construction. Given the current size and configuration of the underground area, the site is unsuitable for the installation of a plutonium production reactor - especially a graphite moderated reactor of the type North Korea has built at Yongbyon. The site is also not well designed for a reprocessing plant. Nevertheless, since the site is a large underground area, it could support such a facility in the future with substantial modifications.