Japan Earthquake: nuclear plants

LabratSR

http://www.tepco.co.jp/en/press/corp...1934_1870.html

And that links to this.

http://www.tepco.co.jp/en/press/corp...20416e0201.pdf

Astronuc

As far as I know, the reinforced concrete containment structure that supports the spent fuel pool is sound, and they added reinforcement to it. The upper containment structures (the structure above the reactor service floor) of Units 1, 3 and 4 were severely damaged - and the refueling bridges and overhead cranes were damaged or basically destroyed. In addition, the areas are heavily contaminated, so their immediate access for personnel is severely limited/restricted.

As far as I know, the spent fuel pools are receiving adequate cooling.

The spent fuel would normally be moved carefully underwater, especially since it may now contain failed rods. If that is the case, then movement of the fuel will be done carefully to avoid additional contamination of the spent fuel pool water and exposure to the personnel and current containment. Any failed fuel could also release Kr-85 (t_1/2 = 10.75 y) as well as other water-soluble fission products, e.g., Cs-134, -137, and fuel particles.

tsutsuji

http://www.nisa.meti.go.jp/shingikai...724/BT-3-6.pdf Hiroto Inoue, JNES, "Seismic Safety Evaluation of the Spent Fuel Pool at the Unit 4", July 24, 2012 (English)

http://www.tepco.co.jp/nu/fukushima-...20723_05-j.pdf Fukushima Daiichi accident workshop, July 23-24 2012 "middle and long term roadmap toward decommissioning and research & development"

http://www3.nhk.or.jp/news/genpatsu-...724/index.html The strontium removal device was publicly presented on 24 July in Yokohama. At present, more than 170,000 tons of contaminated water are stored at Fukushima Daiichi. In the device that was shown, nuclides contained in the contaminated water are adsorbed by resin in a stainless steel tank. By passing through different tanks, up to 62 nuclides can be removed, it was said. This way water can be decontaminated down to the level specified for release into the sea, which is a precaution against the risk of leaks into the environment. The facility will be installed at Fukushima Daiichi by the first 10 days of September, and then the test run will be started. For the time being, the decontaminated water is planned to be stored in tanks, but what will be done in the future has not been decided.

tsutsuji

Fukushima Daiichi accident workshop, July 23-24 2012

http://www.nisa.meti.go.jp/shingikai...23/program.pdf program

http://www.nisa.meti.go.jp/shingikai...23/240723.html presentations, July 23

http://www.nisa.meti.go.jp/shingikai...24/240724.html presentations, July 24

http://www.tepco.co.jp/en/nu/fukushi...20723_05-e.pdf Tepco presentations, July 23

http://www.tepco.co.jp/en/nu/fukushi...20724_02-e.pdf Tepco presentations, July 24

zapperzero

Yet another MAAP accident simulation, yet another presentation wrt presumed causes of the explosion at #4, yet another iteration of the plan to find and plug leaks of radioactive water. I wonder, when will the simulations and projections start being replaced with actual data?

etudiant

Well, it seems that the plan is to reprocess the decontaminated water sufficiently to be able to dump it, although 'no decision has been made'. That is pretty unavoidable, as otherwise there would be need to eventually store several million tons of processed cooling water.
The rest of the work is going deliberately slowly, which seems sensible.
There is no prospect of doing much with the reactors in this decade, apart maybe from emptying the spent fuel pools.
So why hurry, if all of the work has to be done by humans? Better to play for time and push the teleoperator technology forward as fast as possible. That way Japan might also hopefully still get something useful out of this disaster.

zapperzero

*sigh* for what it is worth, I will repeat what I have said here and in other fora. The site remediation work will, must be slow. This, however, should not be seen as an excuse to not instrument the site and not do forensics.

As for pushing teleoperator tech: don't be ridiculous, what is being done now is so far behind the curve, it would be funny if it weren't sad.

Humans are constantly being sent into high radiation fields to manipulate door-handles and other such things; contact with tele-operated machines (no they are not robots) is being lost, as if wi-fi repeaters, Faraday cages and lead shielding had not been invented yet.

In other words, the survey/forensics work is underfunded to an incredible degree.

etudiant

Sadly, your comments are indisputable.
The site management has not changed since the accident, even though the emergency is past. There has not been any recognition that TEPCO is a power utility, not a nuclear cleanup expert.
The site needs a separate management, divorced from TEPCO, tasked solely with performing this cleanup. Leaving TEPCO as a paymaster avoids the problem of setting up a very visible, very costly remediation authority and ensures the site management remains eager to minimize the outlays required. The cheeseparing evident all through the past year makes sense for the TEPCO controllers, but is surely penny wise, pound foolish from a national policy perspective.

jmelson

Well, that's THE problem. In fact, TEPCO cheapness is what CAUSED the accident, from
the siting to the resistance to fortifying the plant against obvious hazards. But, TEPCO
is so big, they SET national policy, not the other way around. And, this has been the
clear situation for decades, where they have had a number of serious accidents.

Jon

HowlerMonkey

yeah......everybody is prepared for a 40+ foot wave and a 9.1 earthquake.

I'm pretty sure this is the scientific discussion thread.

The apportioning of blame thread is elsewhere.

etudiant

Well, if the fixing process is starved for funds, that is a factual operational issue imho, not an apportioning of blame.
Also, the certification process is usually somewhat respectful of local conditions.
Japan has excellent data on earthquakes and tsunamis going back over 1000 years.
Disregarding that record seems a mistake, in retrospect.Whom to blame is another topic.

jmelson

The 9.1 magnitude earthquake was certainly at the upper end of what Japan experiences,
but they HAVE had earthquakes of this magnitude before. The 15 m tsunami run-up
is guaranteed in Japan, you just have to wait long enough for one of those to hit your
particular region.

Their earthquake resistance pretty much handled the event (we think, but there MAY have been some serious damage that has either been covered up or not discovered yet due to
difficulty inspecting parts of the plant.) One area where there seems to be a LOT of damage is in the water-tightness of the plant basements, where they seem to have massive water
leaks, now.

But, since the tsunami threat was completely known and they knew their defenses were very inadequate, this seems to be a serious shortcoming of NISA (is that the right agency?) to make TEPCO harden the plant against the tsunami risk. So, that's why I made the comment about
TEPCO setting policy.

Jon

gmax137

really? when was that?

Actually, what is important is the ground motion at the plant site, not the magnitude of the 'quake (which is an attribute at the location of the earthquake itself). IIRC, the motion at Fukushima Dai-ichi did exceed the design basis (well, what they call the 'back-check' motion, which is like the latest design basis), but not by too much.

I don't know about 'completely known' but I think most agree that the design basis tsunami was far too low. That (in my view) is a failure by the regulator and the licensee. They both had to close their eyes and say "I don't believe it will happen."

SteveElbows

I cant say I've been terribly disappointed with the real data so far, simply because I never expected it to be easy to obtain lots of high quality data and facts even if the operations were being carried out by the best resourced, most competent and open organisation imaginable. I want to know more, but some of the limitations are down to limitations of technology & science, not just lack of will or resources.

It strikes me as rather normal to be relying on model analysis for a range of things, and I was not expecting to learn much more about the cores of the reactors or much inside containment at this point.

Rather my main complaints are to do with the story told early on, lack of good data for people living there to act rationally upon, etc. There are things I wish had been presented to us in a far more cohesive manner, but plenty of it would still be model-based or speculative at this point. I actually want more speculation on various possible forms of containment breach, corium pathways etc, but I dont expect hard facts to emerge on this front any quicker than they have so far. But for example when they lowered that probe into the torus room and its water, and got some rather high readings, I would like either the company, government agencies, journalists or whoever to talk about what possibilities the resulting data, however limited, points to.

Perhaps my biggest complaint about data/facts since the first weeks of the disaster has been photographic etc evidence with decent analysis of various potential containment failure points. To say that they didnt go out of their way to draw attention to or explain even the stuff they have published about this sort of thing would be an understatement.

Meanwhile for those taking a more visual approach to observing the aftermath of the disaster, it seems that in a few hours the webcam will be moving to a new position that should afford us a better look at the work going on at reactor 4 (now that there is no interesting demolition stuff going on) & hopefully a vaguely reasonable view of 3 as well.

HowlerMonkey

Using the data from 1895 (edit), the nuclear power plants were carefully placed outside or at the edges of the new madrid area where the most damage occurred.................for a 6 on the richter scale.

I'm pretty sure more than a few would be in danger if a 9.0 hit in new madrid.

My point is that I doubt anybody can successfully guarantee against damage from a 9.0 earthquake.

mheslep

I'm inclined to always ask, what's the appropriate risk model (cost/benefit) in the case of 9.0 earthquake in an area with a nuclear power plant? That is, dedicate some amount of funds, whatever you like ($300B?) to prevention of damage to life and property in the case of that 9.0. What should be the priorities? Based on what I hazard to guess would save the most lives, near the top of my list would be reinforcement of existing structures (residential/office/municipal), gas lines, dams and the like, then perhaps training for emergency services. Or build sea walls at sites near the sea. Maybe down around 10th on the list I might start allocating money to improvements at the local nuclear plant.

Tepconium-311

Reinforced structures, gas lines and all this don't really matter in an exclusion zone, I guess.
And, how much is the genetic degenerative damage to be valued? Is genetic health of later generations a "priority" at all?
If you could ask your descendants seven generations later, they might strongly disagree with today's "priorities".

Hmm, could the pipe simply have molten and welded shut?