Japan Earthquake: nuclear plants

Yes, the article is real. I obtained a copy of yesterday's Asahi Shimbum from a neighbor.

The article is on page 5 from the 15th May. I've scanned the full article for those who are interested.

Just can't remember the Hindenberg mushroom cloud and that was a big hydrogen sucker.<..>

Thanks for looking more closely into that!

1. Yes, that might be true in this case. But another safety feature that seems to be missing are redundant SFP "core spray" lines.

2. Oh, ok, that might explain the possibility of pre-existing corrosion on the roof structure. OTOH, isn't the SFP water cooled, so that in principle it shouldn't be hot and moist there?

3. Yes, one probably would need more cooling capacity, if so far one relied on part of the cooling done by evaporation.

4. Agree, you don't want a concrete slab to fall onto your fuel (that's a somewhat recursive requirement...).

5./6. Yes, so additional venting and level sensors might be needed. But isn't the water level in the pool monitored by some sensor anyway?? E.g. that skimmer tank water level sensor?

One possibilty that avoids some of those points would be to not cover it completely, but only so much that no big object can fall in.



Interesting, thanks for the link (Haven't had time to read it fully yet, though.). I think they should reconsider such threats in view of Fukushima. I mean it seems pretty obvious now that SFPs "on the attic" are a major possible security and safety risk.



I would hope so to, although that might deserve a different thread, such as lessons learned or reconsidering BWR safety. And my question about SFP shield plugs was not only with regards to the roof collapsing but also to threats such as airplane crashes, as considered in the document linked to by jlduh.



See the attachment in this post by M&M http://www.physicsforums.com/showpos...postcount=6534 . I browsed through the whole NRC document now, but I could not find any additional details about the "Fuel Storage Pool Shield Plugs", 4x 4.5 tons, mentioned there. There is also "Fuel Transfer Shield/Cattle Chute", 2x 16.5 tons, and the "Fuel Pool gates", 2x ~1 ton. These sound more related to the shield wall and gate between the reactor well and the SFP.

I found a list of radiation monitoring equipment instead, with detector types and measuring ranges if anyone is interested in that. It's on p. 68 & 69 (one page is missing), Table 11.5-1 "Process and Effluent Radiation Monitors". CAMS seems to be a different sub-system, it is not on that list AFAIKT. There are a whole bunch of lists of other instruments and stuff in that document, as well.

nothing outstanding or surprising. the clueless are promptly learning that a: the radioactivity is distributed in spots, and VERY much in spots (several orders of magnitude difference between hotspot and area around it) and b: the poorly done monitoring misses those spots. Then they will learn that c: even good monitoring will miss many of those spots.
On to food testing when they will 'discover' that a good chunk of radioactivity is in samples hundreds times above limit, which are rare, and aren't stopped effectively by traditional random sampling.

Yes, the article is real. I obtained a copy of yesterday's Asahi Shimbum from a neighbor.

The article is on page 5 from the 15th May. I've scanned the full article for those who are interested.

Radiolysis applies only on molecules with covalent bonds. NaCl has ionic bonds - as it solved it becomes a mix of separated Na+ and Cl- ions immediately.

Mudstone is a second class bedrock. If exposed, it would erode rather rapidly compared to say, granite.

Thank you. So mostly a mess to clean up, then, from getting seawater in a reactor, and not necessarily a corrosion concern?

Thank you. So mostly a mess to clean up, then, from getting seawater in a reactor, and not necessarily a corrosion concern?

Thank you. So mostly a mess to clean up, then, from getting seawater in a reactor, and not necessarily a corrosion concern?

No, certainly not. I am just saying that the simplest explanation that is consistent with the evidence is not consistent with the claim of anyones seeing the ignition. You can uphold the claim only by adding more assumptions to the explanation, however these assumptions would seem to be added, not to make the explanation consistent with the evidence, but to make it consistent with this extraneous claim.

The other question is, can this second fine tuning be done in a timely and reliable manner?

There are only a few images from the period after 3 blew but before 4 went up.

I dont think the resolution is high enough to be 100% sure, but it looks to me like there was already debris fallen onto the pipe in the place where it is later shown to be broken. And I think its always been a pretty likely bet that it was falling walls of reactor 3 that caused the damage.

Corrosion in salty water is in general much faster than in fresh water, so it can be a problem - but not because of the radiolysis.

In this earlier post I quoted TOD commenter donshan who spoke authoritatively on corrosion issues:

" I do question the use of seawater cooling. I hope the Japanese have considered the danger they have created by introducing oxygenated seawater into this stainless steel piping and pressure vessel at boiling temperatures. These stainless steels are extremely susceptible to chloride stress corrosion cracking:

Since residual weld stresses and tensile stress in piping, valves, control tubing, etc. are always present, Standard Operating Reactor water quality standards require keeping chlorides at parts per billion levels. Seawater has about 3.5% or 35 grams per liter of salinity!!! (i.e. 35,000,000 parts per billion)

I have no way of knowing how many days they have before a stainless steel component suddenly cracks, but if it were me, I would be advocating an emergency program to get pure deionzied cooling water back into this stainless steel system ASAP. In laboratory tests in boiling chlorides, cracking of stainless in tensile stress can occur within days- they have at most a few months if they keep boiling sea water in this system and yet another disaster occurs."
http://www.energybulletin.net/storie...burning-issues

Then how do deal with that kind of hot spots, that's all the question. 1) Expanding the evacuation zone in a circular manner with increased radius around most of the hotspots is a solution... more easily done in Ukraine than in Japan due to population density, i admit! 2) Do a real fine tuning based on reliable and updated data. But even this could lead in the future to much more evacuations if hotspots multiply...

The other question is, can this second fine tuning be done in a timely and reliable manner?

In an article dated March 25th dealing with Fukushima Daiichi seawater corrosion issues, Euan Mearns made the following quote :