North Korea’s Yongbyon Nuclear Research Center: Major Activity at the Five Megawatt Reactor.
▻https://www.38north.org/2018/04/yongbyon040418
Commercial satellite imagery from March 30 indicates that North Korea may have shut down the 5 MWe (plutonium production) reactor for the time being. A major excavation project has also begun near the cooling water outfall, which, when coupled with recent efforts to dam the river below this point to create a reservoir, could indicate an attempt to provide a more steady flow of water into the facility. This would allow for the reactor to run more continuously and safely in the future.
There is also new truck activity at the reactor, the purpose of which is unclear but could include maintenance or repairs, the movement of spent fuel rods to the Radiochemical Laboratory from the spent fuel storage pond, or the offloading of fresh fuel to the reactor. Despite the apparent reactor shutdown, there was no evidence (as of March 30) of plutonium reprocessing taking place at the Radiochemical Laboratory. However, this development should be monitored closely in the future.
At the Experimental Light Water Reactor (ELWR), work continues on an adjacent building that may be a laboratory or for engineering support, but there are no obvious signs that the reactor is approaching operational status.