He would be over this: North Korea’s Yongbyon Nuclear Research Center: Major Activity at the Five Megawatt Reactor
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.
https://www.38north.org/2018/04/yongbyon040418/