Surely the increased water injection reflects the desire to avoid turning the inside of the enclosure into a radioactive steam bath.However, afaik, the residual heat of the reactor 1 core is now down to about a megawatt. Assuming 1 calorie equals roughly 4 watt seconds, that is about 900 million calories/hr, dumped into 8 tons, about 8 million grams, of cooling water, well over 100 calories/gram. So the 8 tons/hr water injection appears insufficient to absorb the heat load without boiling. Presumably TEPCO estimates the residual heat to be less than 1 megawatt, but it still seems a marginal cooling flow rate. The continued poor performance of the water processing system, running at around 40% in the latest JAIF summary, may be constraining TEPCOs ability to cool more aggressively.