I forgot to update the news of 230-tonne leak at Fukushima I Nuke Plant but toward the end of TEPCO's press conference on December 18, the initial result of the nuclide analysis came in, and the number was rather high.
The trench water: 4200 becquerels/cubic centimeter (or 4.2 million becquerels/liter)
The water dripping from electrical duct: 0.13 becquerels/cubic centimeter (or 130 becquerels/liter)
No news yet on other nuclides, though Asahi Shinbun says cesium-137 was 5400 becquerels/cubic centimeter. If that's the case, the cesium total would be 9600 becquerels/cubic centimeter of 9.6 million becquerels/liter. It is not as radioactive as the untreated, contaminated water (which is about 100 times as radioactive than this trench water), but still high for a plant that has achieved a "cold shutdown".
TEPCO should announce the result of the analysis in today's press conference.
In the press conference, TEPCO repeated it didn't exactly know where the water had come from or when (anytime between April and December 18), though they said it must be either groundwater or dew condensation water. So the press had to speculate or use their own judgment to write up their articles.
Yomiuri took the safe (TEPCO's) line saying the water is groundwater. (Never mind that the groundwater in the trench is so "hot", where as nearby subdrain water is not.)
Asahi and Jiji Tsushin took the daring line saying the water is from the nearby building that stores the highly contaminated, pre-treated water.
Kyodo News took the best of both worlds as it said the trench water must have come from the highly contaminated, pre-treated water stored in the nearby building, and it got diluted by the water dripping from the electrical duct which does seem like groundwater judging from the cesium density.
TEPCO does say the trench does not connect to the ocean, but all that means may be that the trench does not directly connect to the ocean. As far as I know, no one has come up with the detailed drawing of the plant's network of drains and trenches and how they are connected.