– #Fukushima I Nuke Plant: 2 Sieverts/Hr on Water Surface in the Reactor Bldg Basement?? (EX-SKF, August 4, 2011):
That’s what a worker at Fukushima I Nuclear Power Plant tweeted on August 4. He was expressing his concern for the radiation if the contaminated water in the basements of the reactor buildings becomes less, as TEPCO plans, because of the water treatment system.
TEPCO says that their plan to treat all the highly contaminated water at the plant is more or less intact; if not by the end of the year as planned, at least by the end of February next year.
This worker is worried that if that means lower or no water in the basement, the basement could become so radioactive; he thinks the melted fuel is in the basement. I don’t know for sure which basement he is specifically referring to, but from his past tweets it could be Reactor 1 where he’s been working to install the heat exchanger for the Spent Fuel Pool.
I have no way of verifying anything he says, but here are some of the things he tweeted:
Water shields radiation. If there’s no water [in the basement], the highly radioactive materials will be exposed. The radiation level at the surface of the contaminated water in the basement of the reactor building is 2 sieverts/hour, and the half value layer of water is about 19 centimeters, and the water is 4 to 5 meters [400 to 500 centimeters] deep…
It could be an outrageous level of radiation… I don’t think they can empty the basement… Personally I think the melted-through fuel dropped through the ICM [In Core Monitor?] pipe or RPV drain to the bottom of [or below?] the pedestal, but no way of knowing how much of the fuel is there unless you go there and look.
Well, if a worker at the plant like me worries about it, I’m sure TEPCO and the government have already thought about it and come up with the solution. But that’s my concern.
I’ve seen a smaller number (14 centimeters) for the half value layer of water.
I don’t remember that the surface radiation level of the basement water was ever released by TEPCO. If anyone is aware, please let me know with the link.
Reactor 1 is where the 4 sievert/hour steam was seen gushing through the floor of the reactor building in early June. So, if the radiation on the water surface is 2 sieverts/hour, that’s an improvement, I guess.
In the so-called “hot spots” in Fukushima Prefecture and the rest of Tohoku and Kanto, we’re still talking in “microsievert/hour”.
At Fukushima I Nuke Plant, the “hot spots” are now in “sievert/hour”.
Remember the good old days when anything exceeding 100 millisievert/hour was considered extremely high at the plant?
Just the “new normal” in Japan, and life goes on, apparently.