SEOUL, South Korea -- North Korea's main nuclear complex was discharging hot wastewater in a further sign that the country has restarted a Soviet-era nuclear reactor there that it had used to obtain plutonium fuel for atomic bombs, an American research institute said on Thursday.
Using commercial satellite imagery, the U.S.-Korea Institute at Johns Hopkins University has been monitoring the nuclear complex in Yongbyon, north of Pyongyang, the North Korean capital. Last month, it reported that satellite images from late August showed steam emerging from a generator building adjacent to the five-megawatt reactor, which it said suggested that North Korea was following through on its vow to restart it.
The restarting of the reactor means that the country can produce weapons fuel again. Until the reactor was shut down in 2007 in a short-lived nuclear disarmament deal with Washington, its spent fuel had been the source of plutonium fuel for the North, which conducted three underground nuclear tests between 2006 and last February. North Korea has also said it is running a uranium enrichment program that can provide it with another type of bomb fuel: highly enriched uranium.
In a report posted on its Web site "38 North" on Thursday, the institute said that a Sept. 19 satellite photo showed hot water being released into the Kuryong River, which meanders through the North Korean nuclear complex. The stream of hot water came from the reactor's generator and turbine building through a recently installed drainpipe, it said. The new buried pipeline, the report said, is part of a new secondary cooling system completed last summer to replace the cooling tower that was demolished in 2008 under the ill-fated deal with Washington.
"The most likely explanation is that the reactor is now operating and the generators are producing electrical power," it said.
Since the 2007 deal collapsed, North Korea has repeatedly warned that it would restart the reactor. Once operational, the reactor burns its fuel rods two or three years before they are unloaded and cooled. Then, engineers can treat them with chemicals to extract plutonium in a procedure called reprocessing. In this way, North Korea secured enough plutonium for six to a dozen bombs, according to estimates by American intelligence officials.
If confirmed, the North's restarting of the reactor, coupled with its uranium enrichment program, is likely to increase international jitters over the North's nuclear capabilities and its potential to export nuclear materials and technologies to other states.
"North Korea is a rogue supplier and has demonstrated the capability and inclination to provide nuclear goods and capabilities to customers abroad outside normal commerce and despite international norms and rules," said a report written by David Albright, Andrea Stricker and Houston Wood. In the report, which was released this week by the Institute for Science and International Security in Washington, they called for better enforcement of sanctions against the illicit nuclear trade by countries like North Korea.
Speaking at the United Nations this week, North Korean diplomats said their country had to develop a nuclear deterrent against Washington's "hostile policy" and that their nuclear weapons "can never, ever, be a political bargaining chip." North Korea now calls itself a nuclear weapons power.
North Korea has recently said it is willing to rejoin six-nation talks intended to end its nuclear weapons program, and its main ally, China, has pushed for the negotiations. But Washington says it is not interested in such talks unless North Korea first demonstrates its willingness to surrender its nuclear weapons.
On Wednesday, Defense Secretary Chuck Hagel met with South Korea's defense minister, Kim Kwan-jin, to sign an agreement to improve their joint ability to respond to nuclear and other threats from North Korea.
This article originally appeared in The New York Times.