SEOUL – Recent satellite images suggest the nuclear reactor seen as North Korea’s main source of weapons-grade plutonium is still not operating at full capacity, a U.S. think tank said Thursday.
North Korea mothballed the Yongbyon reactor in 2007 under an aid-for-disarmament accord, but began renovating it after its third nuclear test in 2013.
When fully operational, the reactor is capable of producing around 6 kilos (13 pounds) of plutonium a year — enough for one nuclear bomb, experts say.
Analyzing satellite imagery from late 2014 to the end of 2015, the Washington-based Institute for Science and International Security (ISIS) concluded the reactor has been operating intermittently or at low power throughout the period.
Using tell-tale operational markers, including steam emissions and hot water discharges, the ISIS experts discerned a pattern of limited operations for a few weeks, followed by an apparent shutdown.
“The reasons for this type of operation are unknown,” the institute said.
Its findings contradict a North Korean statement in September last year that all facilities at the Yongbyon nuclear complex were working normally.
The ISIS experts did detect signs that a gas centrifuge plant for enriching uranium was operational, given snow melt on the roofs of the plant’s main buildings.
Activity at Yongbyon is closely monitored for any sign of reprocessing activity.
At some point North Korea is expected to shut down the reactor, discharge the spent fuel, and chemically process it in a nearby radiochemical laboratory to extract weapons-grade plutonium.
North Korea has carried out four nuclear tests since 2006, the most recent being last week when it announced it had detonated its first hydrogen bomb.
Experts have disputed the hydrogen-bomb claim, saying the yield from the test was far too low for a full-fledged thermonuclear device.
As the U.N. Security Council grappled with a response to the underground blast, North Korea’s U.N. mission claimed Wednesday that its test showed that it could now “wipe out” the United States.
North Korea said the test “scientifically proved the power of the smaller H-bomb.”
A Security Council diplomat said Wednesday that the U.N.’s most powerful body is working on a resolution that imposes tougher sanctions on North Korea to reflect the claim that it tested a hydrogen bomb, which is “a step change” from its three previous atomic tests.
The diplomat said all 15 council members agree that North Korea should be denuclearized, and this will be reflected in a new resolution.
U.S. President Barack Obama and Russian President Vladimir Putin agreed over the phone Wednesday that the international community should get tough on North Korea in the wake of the nuclear test.
Obama and Putin agreed on the importance of “a strong and united international response” in defiance of U.N. Security Council resolutions that demanded Pyongyang suspend any activities related to nuclear programs, according to the White House.
At the same time, Putin advocated “all relevant sides exercising maximum restraint and not taking action that could incite military escalation in Northeast Asia,” a Russian statement said.
North Korea’s U.N. mission circulated a report from the country’s news agency saying the Jan. 6 test wasn’t to “threaten” or “provoke” anyone but was indispensable to build a nuclear force “to cope with the U.S. ever-more undisguised hostile policy” toward the Democratic People’s Republic of Korea, the country’s official name.
It said North Korean scientists and technicians “are in high spirit to detonate H-bombs … capable of wiping out the whole territory of the U.S. all at once as it persistently moves to stifle the DPRK.”