By Wolf von Baumgart, Staff Writer
According to an analysis  by William Mugford and Jack Liu, posted on 38north.org, interpretation of Aug 22 commercial satellite imagery may suggest that recent increased activity at North Korea’s key nuclear R&D facility is a preliminary indication that the DPRK may be producing or preparing to produce weapons grade plutonium.
[ Photo: (c) 2015 Wolf von Baumgart ]
The site’s main reactor, located approximately 60 miles North of Pyongyang, was previously mothballed and disabled under an agreement reached at the six-party talks in October, 2007. According to the report, “Developments at Yongbyon are cause for concern and should be monitored closely by the international community to determine their purpose.” 
The Yongbyon Nuclear Scientific Research Center consists of a 5-MWe graphite-moderated reactor (with annex), radiochemical laboratory complex, spent fuel rod receiving building, reprocessing building, chemical storage building, administration building and support buildings. 
Heavy vehicle tracks (indicating possible delivery of materials and/or renovation activity) between the main reactor hall, spent fuel receiving building, radiochemical laboratory and support buildings; together with the number and depth of the tracks and the presence of piles of unknown materials gives rise to speculation that North Korea may again be increasing its stockpile of weapons grade plutonium [93% Pu-239 or greater] from spent uranium fuel rods.
The analysis further stated, “Typically, a full core of spent fuel rods would be unloaded every 2-4 years from the 5 MWe reactor, producing enough plutonium for up to two additional nuclear bombs.” 
It must be cautioned, however, that given the limited amount of relevant commercial satellite imagery available (and its lower resolution), the lack of supporting remote sensing radiological data and ground-based intelligence confirmation, it is premature at this point to draw a dispositive conclusion. [WvB]
Based upon the limited information available, the report offers the following preliminary explanations:
(1) Significant maintenance or renovation operations are ongoing as part of a DPRK program to modernize and upgrade the Yongbyon facility.
(2) Contaminated equipment from the 5-MWe reactor is being moved to the reprocessing facility for storage or decontamination.
(3) Major vehicular traffic encompassing the 5-MWe reactor, radiochemical laboratory complex and the spent fuel receiving building may indicate preparations for unloading spent fuel rods from the reactor for the purpose of producing new plutonium.
In the event that latter scenario (3) proves to be true, it would represent an important step towards the further development of North Korea’s nuclear weapons stockpile. Scenario (1) would also, in some measure, possibly indicate the DPRK’s intent.
According to a recent UPI report,
Voice of America reported Monday, September 7, that Yukiya Amano, Director General of the International Atomic Energy Agency, stated that the IAEA has observed renovation and construction activities at various locations within Yongbyon and indicated that the international community is closely monitoring developments at the facility. “These appear to be broadly consistent with the DPRK’s statements that it is further developing its nuclear capabilities”, he said, earlier this week.
According to the 9/9/2015 Guardian, a recent report by US researchers warned that North Korea appeared poised to expand its nuclear program over the next five years and could possess 100 atomic bombs by 2020, in a worst case scenario. 
This could be another attempt by the DPRK’s Leader, Kim Jung Un to repeat North Korea’s historical cyclical foreign policy and geopolitical pattern of creating a crisis, extracting concessions and subsequently easing tensions until the next cycle. [WvB] 
There are no measurable indicators, as yet, as to what inductive political effect, if any, this will have on the ongoing approval process of the Joint Comprehensive Plan of Action with Iran.
 The original report: North Korea’s Yongbyon Nuclear Facility: New Activity at the Plutonium Production Complex
is available at: http://38north.org/2015/09/yongbyon090815/
 38 North is a Johns Hopkins University-based program of the U.S.-Korea Institute (USKI) at the Paul H. Nitze School of Advanced International Studies (SAIS )
 Further descriptive and historical information on the DPRK’s Yongbyon Nuclear Scientific Research Center is available at: http://www.globalsecurity.org/wmd/world/dprk/yongbyon.html
 Comprehensive background material on DPRK fissile material stockpiles is available. A detailed report: North Korea’s Estimated Stocks of Plutonium and Weapon-Grade Uranium (8/16/2012) by David Albright and Christina Walrond of the Institute for Science and International Security (ISIS) is available at: http://isis-online.org/uploads/isis-reports/documents/dprk_fissile_material_production_16Aug2012.pdf
 A more political analysis on a previous restart of Yongbyon plutonium reactor is given in a 9/12/2013 New York Times article: http://www.nytimes.com/2013/09/12/world/asia/north-korea-appears-to-restart-plutonium-reactor.html?_r=0
 Other media references are listed below: