Tepco said it increased the amount of injected water, some of which contained boric acid, at 4:24 a.m. Tuesday. Reactor 2 is now being cooled with 13.5 tons of water per hour, up from 10.5 tons. The boric acid is being used to prevent a sustained nuclear chain reaction, or recriticality.
Tepco changed pipes and the amount of coolant water in reactor 2 last month, and suspects the water did not sufficiently cover some parts of the pressure vessel, as only a small amount was injected through a pipe designed to take in large amounts.
Nuclear disaster minister Goshi Hosono told reporters;
“This was a process to enhance stability, but it has become clear that there is a possibility (the replacement work created) an unstable situation temporarily.
“We have to consider matters in an even more careful way,”
Source: Japan Times
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