Water Leak Hinders Effort To Bring No. 1 Reactor Under Control

Nikkei ^ | 05/13/11

[TigerLikesRooster]

Friday, May 13, 2011

Water Leak Hinders Effort To Bring No. 1 Reactor Under Control

TOKYO (Nikkei)--Tokyo Electric Power Co. (9501) needs to rethink its plans of achieving a cold shutdown at the Fukushima Daiichi nuclear power plant's No. 1 reactor by October now that it has become certain that radioactive water is leaking from the crippled facility.

The utility, known as Tepco, has so far pumped roughly 10,000 tons of water into the reactor to keep the fuel rods from overheating. Given that the pressure vessel has a capacity of 360 tons and the containment vessel can hold 7,400 tons, it appears likely that both are damaged.

The fuel rods may have melted and formed a lump at the bottom of the pressure vessel. The temperature of the pressure vessel is a relatively low 100-120 C, so the outside of the melted mass is believed to have shed some heat, but if the inside is still hot, it will take some time to cool down.

[TigerLikesRooster]

P!

[wolfpat]

Cool. Somebody’s finally gonna see what Corium looks like.

[justa-hairyape]

This could be very bad news. 1,000’s of tons of radioactive water mixing into the ground water and the sea. We are perhaps brewing something, rather unique, I would suppose. And that is just what is behind door #1, Bob !

[TigerLikesRooster]

What do you think about the bad structural integrity of reactor buildings? If they do crash, I suppose this could create real problems.

[TigerLikesRooster]

Sorry. I did see your comments on this matter in another thread now.

[mvpel]

Here's what corium looks like when hot, at Chernobyl:

Hopefully this news from Japan should put the hysterical and ridiculous predictions of a Hollywood-inspired melted tunnel into the bedrock to rest.

[meatloaf]

“The utility, known as Tepco, has so far pumped roughly 10,000 tons of water into the reactor to keep the fuel rods from overheating. Given that the pressure vessel has a capacity of 360 tons and the containment vessel can hold 7,400 tons, it appears likely that both are damaged.”

What doesn't make sense is that there are three containment vessels involved, the reactor pressure vessel, the drywell, and the containment building itself. The reactor sets inside the drywell which is inside the containment.

There was mention of an effort to flood the drywell and thus submerge the reactor. It's conceivable that the drywell could have been damaged and water is leaking into the containment building. The reactor is holding pressure. That's not an issue.

That leaves the spent fuel pools which are outside the containment building which they used the concrete trucks, fire engine's and helicopters to flood, That was the source of the radioactive water in the turbine building.

[justa-hairyape]

This reactor is not holding pressure. It fell close to 1 atmosphere when they increased the water input and lowered the internal temperature. They backed off on the water injection rate because of that. Then they thought about it for awhile and decided to flood the entire containment structure and the pressure vessel. So the flow input was increased again.

According to one blog report, they were able to replace a couple of measurement instruments connected with the reactor vessel. One was the water height. The new instrument indicated almost no water in the vessel. That lead them to make the conclusion that they cannot possible flood the vessel. IE - It should already be flooded.

[TXnMA]

"That leaves the spent fuel pools which are outside the containment building..."

~~~~~~~~~~~~

Not exactly so. In a GE Mark 1 reactor installation:

The fuel storage pool (shown immediately to the right of the top of the reactor containment in this graphic) is inside the secondary containment building.

The big problem is that the pool walls and floor are concrete (and suspended on an upper floor). Concrete can crack (and, therefore, leak) under the tensile and flexural stress imparted by an earthquake (or hydrogen explosion inside the building).

That entire Mark 1 design is riddled with such faults...

[meatloaf]

That is correct. I was using the word containment to mean the primary containment. The spent fuel pools are outside the primary containment. Since the secondary containment was destroyed by the hydrogen explosions, the water pumped into the fuel pools could go anywhere.

[meatloaf]

Can you post links to that info? Different sources are using the same terms to mean different things. Generally the media does not understand how many structures are involved in the design.

[justa-hairyape]

The blog that had translated the Japanese announcements from Tepco, mysteriously had its three blog post removed by Blogger. There is a WSJ article that drudge has linked that covers the main aspects of the story.

At Reactor, Damage Worse Than Feared

With respect to the spent fuel pools, from what I have read they do not inject water into the pools continuously. They just pump it in for awhile until they conclude the pool is filled with water. Then they stop injection for awhile.

[meatloaf]

“With respect to the spent fuel pools, from what I have read they do not inject water into the pools continuously. They just pump it in for awhile until they conclude the pool is filled with water. Then they stop injection for awhile. “

In the early days of the emrgency it seemed like they were keeping a constant flood of water going into the pools msimply because when the cooling pumps shut down they had to replace the water that was boiling off. Thanks for the link.

[blueplum]

there must be some substance known to man that could be added to the water to seal a leak

like the stuff one puts in radiators or, even lots and lots and lots and lots of black pepper

surely the environmental impact of any such additive would be less than the impact of what amounts to a continuous leakage of radioactive wastewater/steam lasting now several months