Possible uneven settlement of reactor 4
Following up this article..Tepco started soil improvement work under reactor4
Mr. Kino, a freelance journalist asked Nuclear and Industrial Safety Agency about the state of the reactor4 building on their press conference of 5/7/2012.
It’s been told that the building was leaning.
(Mr. Kino → K, NISA → N)
K : About the state of reactor4, has anyone surveyed the building ?
N : Like tilt ?
K : Yes, tilt and other points.
N : We surveyed the water level of SFP4, and confirmed it’s not leaning.
K : Apart from the water level, hasn’t anybody surveyed the level of the building ?
N : Because we confirmed it was not leaning, we think there is no problem with the building.
K : I can not understand how you can check the entire building only to see the water level now that the whole building is deformed. (It is not enough only to check the water level of the pool.) Has nobody surveyed the building even from the outside ??
N : No, nobody has surveyed it.
K : Has anyone conducted soil survey around the reactor building ?
N : No, I don’t think so.
K : Some people point out that the ground is having uneven settlement around the reactor 4 building. If you have’t conducted high and low instrumentation, you don’t even know that ?
N : Earthquake may have caused ground subsidence in the area of Fukushima plants, but because the building is on the bed rock, the state of the ground is different from the building area and other areas.
Seismic evaluation of the building was conducted in the most severe standard.
K : but it is rational to think the basement of the building has been damaged underground too. Do you evaluate the basement floor is completely safe ?
N : We reinforced the SFP4 based on the most severe seismic evaluation.
K : No, I mean, apart from the reinforcement of the building above the ground, now it can be assumed the basement of the building is damaged, and there may be uneven settlement around the reactor, how can you guarantee the building is not leaning ?
N : If the building is leaning, we can tell it by checking the water level of SFP4. Inspector actually entered the building and confirmed the safety visually.
K : OK. There is no plan to survey the building from outside ?
N : I haven’t heard any specific plan about building survey from outside. We would need to start it from evaluation of the bench mark to conduct building survey.
Tepco started building the cover of reactor4 building to remove 1500 assemblies of spent fuel from 4/17/2012. They can not design the cover without knowing the exact length, height, and ground bearing capacity by detailed surveying.