"Workers pumped concrete into the shaft Saturday, but by the end of the day, the flow of water into the ocean had not diminished. Engineers speculated that the water was preventing the concrete from setting, allowing it to be washed away.
Tepco officials said that on Sunday morning they would explore using a polymer — a type of quick-setting plastic — to plug the leak."
Wow, this doesn't seem like a technically outlined engineering feat. They literally dumped wet cement on the area of the leak and hoped for the best. Meanwhile, it looks like core pressure, temperature and radiation for unit 1 are creeping back up:
Not much progress made lately. I hope the high exposures at the plant aren't starting to affect the worker's mental faculties. One plant worker fell into the ocean yesterday when the barge arrived. That was an exceedingly reckless blunder given the circumstances; he must have been dizzy and lost his balance.