Recent satellite images indicate that North Korea's plutonium-production reactor is operating again following a reported possible shutdown.
In commercial satellite photos taken as recently as this month, water can be seen pouring out of the five-megawatt electric reactor, according to a Wednesday analysis by the Institute for Science and International Security.
The discharged water is most probably coming from a secondary cooling system used to chill the gas produced from the nuclear-reactor core, concludes the assessment by David Albright and Serena Kelleher-Vergantini. The water indicates either "testing or ongoing operation" of the graphite reactor, they said.
According to a separate image analysis by 38 North issued earlier this month, between December and February, Pyongyang may have temporarily shut down or significantly curtailed operations at the reactor in order to conduct emergency maintenance work necessitated by recent flooding.
None of the April photographs analyzed by the ISIS experts, though, showed signs of steam emanating from the reactor's turbine building. Were steam being regularly emitted, it would indicate regular reactor operations, according to the analysis. It noted, however, that the lack of steam did not necessarily mean the facility was not being consistently operated.
North Korea disabled the graphite reactor in 2007 in accordance with a now-dead denuclearization agreement with Washington. The Kim Jong Un regime last spring announced that it would reactivate the reactor so it could begin producing fissile material for the country's nuclear arms program.
Separately, North Korea's uranium enrichment plant at Yongbyon appears not to have had any new exterior work done on it since it was last analyzed by the institute in December. This could mean that a previously detected construction effort to double the size of the enrichment facility has been completed, the institute said on Wednesday.
"North Korea could now be concentrating on installing equipment and even centrifuges inside the expanded building," according to the analysis.
Correction: This article was changed after publication to accurately describe the graphite reactor analyzed by the Institute for Science and International Security.