flooding

11:06 Oct 17, 2016 

The building receives water from a number of sources:
- primary and secondary leaks
- water thrown by the roof to cool down the core
- leaking used fuel pools
- rain and such (probably negilgible, but the roofs or the buildings are damaged)

So the estimate of the contribution of the ground water to the total water entry into the buildings (that does actually flood them or not, but this creates effects like the ones of an external flooding) is 400 m3

07:32 Oct 17, 2016 

There are two sources of water and two things that are being flooded.

400m3 per day of water is being injected into the core to cool it down. This is referred to as "flooding" the core (but not actually used that way in your text). This (now radioactive) water is leaking out of the containment into the buildings.

In addition, another 400m3 is coming into the buildings from groundwater. This total of 800m3 per day is flooding the buildings.

In both cases, flooding means (partially) filling with water. The difference is that it is intentional for the core and unwanted in the buildings.

23:25 Oct 16, 2016 

As described in Technical Volume 1, from the early stages of the accident, water was injected into the reactor pressure vessels of Units 1–3 to provide cooling; at the time of writing, this process is still continuing. Some of this water drains into the lower levels of the reactor buildings and, as it comes into contact with melted fuel, it contains radionuclides. Currently, the flow rate of injected water is about 350–400 m3 per day. The topography of the Fukushima Daiichi NPP is such that groundwater flows from the hills to the west of the site down to the eastern shore of the Pacific Ocean. Some of this groundwater enters the reactor buildings and turbine buildings of Units 1–4 and also passes into auxiliary buildings. TEPCO estimates that the daily contribution of groundwater to the flooding of these buildings is about 400 m3.



** m3 means "m" to the power of three