Japan Earthquake: nuclear plants

etudiant

Much the largest item is the 'purified' water left over after decontamination, now about 200,000 tons. TEPCO has been refused permission to dump this water, because it still has some residual contamination.
That would give a 30 foot deep lake about 0.6 miles square (8 meters deep and 1 km/side) in 40 years.
Earthquake resistance of the water storage is probably marginal.

Jorge Stolfi

People who keep an eye on the Fukushima Daiichi weathercam have often claimed "massive fires" or "massive steam releases" from the reactors which are easily explained as fog, clouds, or low-light-level camera noise

However, this video http://t.co/wa9KXinD , recorded yesterday (feb 28), apparently shows a substantial release of steam from the ground near units 3 and 4, starting at ~00:38. It does not seem to be fog (too low, very localized and persistent). It does not seem to be smoke (disappears instead of just dispersing).

I cannot imagine what that "steam" could be. AFAIK the water processing plant does not use steam. The reactors and basement water should be too cool. I cannot think of a cleaning or maintenance activity that would use steam. Any explanations?

etudiant

The video is sharply accelerated, as is reflected in the speedy passage of clouds and airplanes, so the steam emissions seem more vigorous than they are in reality.
That said, the still ongoing decay is about a megawatt per reactor, so steam on a winter day would not be unexpected.
The location of the emissions does suggest a below ground source not central to the reactor core, which may be worrysome.

Yamanote

Okaaay... So assuming that a PCV gas treatment system is now in service for unit 3 as well, the released steam must come from the exhaust of this system, right?

Can anybody confirm that the exhaust is located in this area?

etudiant

It is not the most obvious location for a gas treatment plant.

Was not the space between reactors 3 and 4 the location of some piece of very radioactive debris, which was later bulldozed over, immediately after the Mar 15 explosions?

Also, was there not some testimony by plant workers about steam coming from out of the ground near the reactors? Which reactor was not clear though.

Yamanote

Well, my point is:
If all the nasty molten fuel stuff has remained inside unit 3's PCV and the gas management system draws off most of the steam, I actually see no other steam release route.

Or did I miss a point?

etudiant

Afaik, there is no gas management system in place other than at reactor 1.
The reactor 4 structure is getting worked on pretty extensively, mostly dismantleing, but the reactor was empty with the fuel in the SPF, where videos still show it to be.
Reactors 2 and 3 are close to unapproachable and are believed to have suffered PCV damage. Any steam from either is likely to be dangerously radioactive.
TEPCO indicates the current air emissions rate is around 10 million bequerels, so the cooling is not yet fully effective.

zapperzero

Steam from a reactor, coming out of some broken pipe in a turbine building?
Smoke from a generator or some other big diesel?

CaptD

I think one or more of the missing Corium(s) are beginning to interact with the groundwater, especially after earth quakes (EQ's) and that is the cause of the "steam" events that are visible in some of the web cameras...

It would be great to place a recording G-Meter at these locations but TEPCO is not making it easy to do so...

Seeing massive amounts of "steam," (which more correctly should be referred to as "radioactive steam" coming from the ground is something quite different than steam coming from what is left of the buildings IMO.

etudiant

The angle of view does not provide any idea of where the steam/smoke is coming from.
There are instants that suggest a single source such as a pipe. It could just be a large engine idling in the cold weather.

Corium interactions with ground water seem a minimal threat when the site has been flooded pretty much since the accident.
The location argues against a direct PCV connection, as it is well outside the reactor perimeter.

SteveElbows

Not sure why you say that, unless we are talking about different sorts of gas management systems. Reactor 2 has had one for months now (thats where the gas sample analysis is coming from for that reactor, Xe133 etc) and reactor 3's started operation on Feb 23rd.

I haven't spent ages studying the video footage but isn't the area in question between reactors 2 & 3, not 3 & 4?

Looking at Tepco status updates covering Feb 28th, there is one operation that could be relevant:

From 8:51 am to 3:45 pm on February 28, according to the investigation on trenches on January 19, 2012, high density contaminated water inside was found inside circulating water pump discharge valve pit of Unit 3 water pump room. Therefore, we started to transfer the accumulated water from the pit to the basement of Unit 2 Turbine Building.

SteveElbows

Anybody got any comments on the radiation readings, photos or videos of the recent robot activity inside reactor 2 building (mostly 5th floor)?

http://www.tepco.co.jp/en/nu/fukushi...20228_04-e.pdf

http://www.tepco.co.jp/en/news/110311/index-e.html

I haven't looked at the videos yet but it was good to see an image of the area above the reactor well, not obscured by barriers this time as they gave the new robot a longer camera arm.

etudiant

Thank you, the suggestion seems a plausible explanation.
Re gas management, my mistake. I was thinking of the emissions management, which is a different aspect.
Gas management has indeed been ongoing for months at reactors 1 and 2.

zapperzero

Well this is odd.
http://www.tepco.co.jp/tepconews/pre.../120228_01.jpg
a large number of pairs of rubber boots are ranged neatly near what seems to be the concrete cap of the reactor well (unit 2). The picture was taken with a robot.
another odd detail in
http://www.tepco.co.jp/tepconews/pre.../120228_02.jpg
there are bits of what seems to be the SFP guardrail (the remains of bottom panels, to be precise) which seem melted and burnt.
there seems to be some discoloration/soot here as well:
http://www.tepco.co.jp/tepconews/pre.../120228_03.jpg

HowlerMonkey

That might be smoke/steam from an internal combustion engine.

I would assume they would eventually repair and start some of the generators or other engine run equipment on the facility with the first start billowing much white smoke.

Just a guess.

Jorge Stolfi

Indeed, my mistake.

r-j

http://youtu.be/fimRJocH_90

This video talks about cracks in the soil at the plant. Which started after earthquakes. Has there been an earthquake near there of late?