TEPCO to modifiy cooling at No. 3 reactor

Tokyo Electric Power will be adding another route of feedwater to the reactor at No. 3 plant at the Fukushima Daiichi site, it has been reported by TEPCO and by various Japanese media.



Readers here already know that No. 3 plant has kept hotter than the others, and we've speculated here (and in comments on posts) a number of times about why this might be. TEPCO feels the same way and has decided that a double feed approach, using the core spray line and the normal feedwater line, is a good way to ensure water flow both above and below the core.



Below we see a section of a TEPCO press release package showing the routing of the systems that will be used.





And below we see a much more technically complete and accurate view of the GE BWR/3 - BWR/4 reactor construction, from APRA files (and which readers here have seen before as well,) this time marked with green to show the location of the core spray header connection to the pressure vessel, and then the location of the actual spray rings ("spargers") that distribute this water on top of the active core region.





Work is already underway to make the alterations seen in the TEPCO drawing; the major work is scheduled for the 25th with full operation of the new arrangement on the 26th. TEPCO will slowly adjust flow rates between the two systems to optimize the temperature drop and system performance; we will report on the effects as the results become available.



10:50 PM Eastern Tuesday August 23, 2011

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