Friday, April 1, 2011

#Fukushima I Nuke Plant: "Where is Radioactive Water Coming From?"

Japan's national regulators and TEPCO still can't figure out where the highly radioactive water is coming from that's flooding the basements and trenches and shafts and how it is apparently finding its way into the ground water. Or so they say. And oh by the way that's got nothing to do with the radioactive materials found in the sea water nearby in high concentration, or so they say.

"Extend and Pretend" continues, on a grand scale.

Yomiuri Shinbun (in Japanese; 1:47AM JST 4/2/2011) has a convoluted analysis of where the water may be coming from and then may be not (original Japanese, then my translation, by paragraph):


Contaminated water with high concentration of radioactive materials has been found in many places in TEPCO's Fukushima I Nuclear Power Plant.


The radioactive water has been found in the basements of the turbine buildings, trenches outside the buildings, and has now been found in the ground water. They [regulators, TEPCO] do not believe the contaminated ground water has anything to do with the contaminated seawater, and they haven't been able to pinpoint how the radioactive materials have found their way into the water.

汚染水に含まれる高い放射性物質は、核燃料棒が一部損傷した原子炉圧力容器内の冷却水が漏れ出したものとみられる。これがどのようなルートで地下 水に紛れ込んだのか。東電は、〈1〉原子炉などに放水・注水して、放射能で汚染された水〈2〉大気中に飛散した放射性物質を含む雨水〈3〉タービン建屋の 地下にたまった汚染水〈4〉建屋の外の作業用トンネル(トレンチ)にたまった汚染水――が地面にしみ込んだ可能性があると見ている。複数のルートが絡んで いる可能性もある

It is understood that the radioactive materials found in high concentration in the contaminated water comes from the cooling water from the Reactor Pressure Vessels, in which the nuclear fuel rod assemblies have been partially damaged. But how has this water seeped into the ground water? TEPCO is mulling four possibilities: (1) water that has been sprayed [on the building to cool the Spent Fuel Pools] and poured into the reactors and got contaminated; (2) rainwater that captured radioactive materials released in the air; (3) contaminated water in the turbine building basement; (4) contaminated water in the trench outside the building. It is possible that there are more than one routes.

Huh? So, the cooling water gets contaminated when the water is pumped into the Reactor Pressure Vessels to keep the fuels inside cool, because the fuel rods are damaged. Why do they (or Yomiuri reporter) have to obfuscate by bringing up rainwater? The (3) and (4) are clearly the same water that comes from (1).

What do they mean exactly by "damaged" fuel rods? From what I've read, it probably means that cladding (cover that wraps around uranium pellets to form a fuel rod) made of zirconium alloy has either expanded and ruptured or has squeezed into uranium pellets (depending on the pressure), and the fuel rods has melted, at least partially, and probably partially fused with the control rods, which contain silver and cadmium among other metals, all the while releasing radioactive materials in high concentration. A meltdown of the fuel rods forms the mass is called "corium".

There are two ways, as far I can figure, for this contaminated water in the RPVs to escape the RPVs.

One way is through the pipes that circulate the contaminated water back to the turbine rooms; either the pipes or valves connected to the RPVs are damaged during the earthquake and started to leak, and the water started to accumulate on the turbine building floor, and then found its way into the trenches and vertical shafts, which, as TEPCO has admitted, may not be leak-proof. And so into the ground water.

However, there has been no news that TEPCO pinpointed the exact leak locations. Partly, at this point, radiation is probably too high in the turbine buildings or reactor buildings for humans to enter and examine.

Another way is through the RPVs themselves, if they are indeed damaged, as indicated already by TEPCO and Nuclear Safety Commission. But if the RPVs are damaged and leaking, they are still housed in the Containment Vessels. Unless the Containment Vessels are also damaged and leaking.

Then the very awkward question would still remain; it's actually so awkward that there's no way I can mention it without being arrested by the Japanese National Police for spreading "false, harmful rumor".

So let me just copy this picture from Yomiuri, and point out something:

The RPV is on the left building, connected to the turbine on the right building. See the dotted green arrow coming from the area where the Spent Fuel Pool is located? The arrow goes from there to the floor of the Reactor building or the passage that connects the two, into the ground. Another green arrow goes directly from the turbine building floor into the ground. A light green oblong blob in the center depicts the ground water.

Now, how would the water go from the floor of the building into the ground? Unless there's a crack in the concrete floor. Is it possible to have a crack in the floor that goes deep enough in a nuclear reactor building?

How is the floor of a reactor building or a turbine building constructed? And how could it crack?

Go read this article in wiki for more on the "corium".


Byte Me said...

Answer to your hypothesis.

Water drains from TH#1 through normal outfall drains (probably to sea). Water is IN TH#1 because pipes are shot thanks to quake or anomalous pressure excursion later on.
Reactor core no longer in original fuel elements as per GE brochure. Low coolant level unhappy with corium melt muscling in on its turf. Big fight ensues. Fight over quickly, RPV compromised - corium goes out to play in containment vessel / torus. Steam explosion (with H2 cherry on top for reactor 1) and corium warms up the concrete containment which is 2+ metes thick rebar.
Unpleasant, and it may gradually be dissolving - certainly the reaction products hence 131, 137Cs and the Cd and Ag isotopes, the 99Tc(metastable) comes from 99Mo another reaction product.
On the plus side, the control rods are maybe still in place in a twisted sort of way -- I think they're made of Hafnium, takes a bit to melt THAT.

I'm not in your country so I can't help in person sadly, but if your "Thought Police" want to take issue with my allegations I'll be happy to do so in public.
Byte Me.

arevamirpal::laprimavera said...

Thanks, Byte Me, I'll let you know as soon as I hear from the Police.

Luckily I'm on the other side of the Pacific Ocean.

But I was thinking what you were thinking. I didn't know how thick the concrete floor was under the containment vessel, but figured there's no way that's cracked in the earthquake. Which leaves only one possibility, which you describe.

I'm trying to find out the control rod material. From the contaminated water, they say they detected silver and tellurium, among others. If you know anything about these exotic elements that I posted here, let me know:

Post a Comment