TEPCO reported a loss of power Dec 5, 2016 for the unit 3 reactor, the one running MOX fuel that was blown up in what strongly resembled a nuclear reaction:
Associated Press. December 5, 2016. Fukushima reactor briefly loses cooling during inspection. The Asahi Shimbun, http://www.asahi.com/ajw/articles/AJ201612050069.htmlTEPCO stated that water remained inside the reactor and there was "no temperature increase or radiation leak from the incident."
One of the melted reactors at tsunami-hit Fukushima nuclear power plant had a temporary loss of cooling when a worker accidentally bumped a switch while passing through a narrow aisle of switch panels during an inspection and turned off the pumping system. The plant operator, Tokyo Electric Power Co., said cooling for the No. 3 reactor, one of the three reactors that melted following the 2011 earthquake and tsunami, was out for nearly one hour Monday until a backup pump kicked in.
Here is a screenshot from the plant Dec 5, 2016 1:39 (TEPCO time stamp):