Thousands evacuate as Fukishima nuclear emergency is declared

[Jan Klimkowski]

A couple of posts from another forum by a person whose moniker is "nuke_engineer". I've followed his posts for several years, pre-Fukushima, and believe him to be generally credible.

Folks,

If there's anything the engineering and scientific community is learning from this disaster is that everything the book smart and academics believe is getting tested and in many cases being proven wrong or not occurring as expected. We've never had a loss of coolant accident where the core melted and went through the containment and so we learn new things and new rules every day. Here's some examples:

An Atomic Bomb is essentially a runaway fission reaction in the A-Bomb type of ordnance. Most people don't realize that this requires a sudden (in microseconds) jamming of a critical mass of Uranium or Plutonium to create the uncontrolled reaction. This means shaped charges and coordinated co-explosions of the shaped charges to force the material into a condensed shape. IMHO, it is doubtful (as far as I see right now) for this to happen at Fukushima, but my experience makes me reluctant to say it's impossible for it to happen. I'll also add that H-Bombs and N-Bombs use very small A-Bombs as triggers, so the odds this will happen in those type of weapons is slight as well. Notice I won't say impossible, because I've already seen the impossible happen several times!

This does not preclude that a terrorist group could bring a nuclear explosive device on-site and detonate this and possibly cause sympathetic explosions and damage, but with a terrorist act the real danger then would be another round of aerial and oceanic contamination.

Regular fission created by bringing fissile materials together with some moderation as well created by just general decay is another matter. It's going on all the time all over the facility. Conventional wisdom would say that over time the fission process should decline, but to our surprise we have data otherwise (I can't go further here) and thus there must be other processes and systems at work we just don't understand yet. Aside from the radiological dangers, the heat generated from these processes has created spontaneous combustion in some cases as we learn that impurities in the fuel rod assemblies as well as the passage of time and regular contamination (rust, stress, strain, etc.) can certainly impeach the so-called safety zones of such materials. Conventional engineering says that over time things tend to stabilize, but the Chernobyl and TMI experience already had taught us that this is not the case, due to other system effects and interactions as well as the problem of loss of intimate and accurate engineering knowledge of the tactical situation as time goes by.

The "dilution" story is also getting some well deserved credibility hits. Although I was aware of but couldn't discuss the classified 1950's report of the then discovery of current "tunnels" in the Pacific which could essentially nullify some of the dilution, I hear now that the report has now been declassified and the Chinese are also working on a similar research project as well as our NOAA crowd. This could prove very interesting and change our comfort level here in the western hemisphere as that story unfolds.

My belief is that most of the Northern hemisphere will be affected in a variety of ways and levels of contamination. I also believe that the US and Canada as well as Latin America may be hit not by contamination via oceanic or aerial means, but by business. Unscrupulous business people could use contaminated seafood, feed or even animals and bring them to the Western Hemisphere and cause a more dangerous situation than the general environmental contamination. We will get hit IMHO by some way we don't expect or our legacy scientific and engineering methods and practices tell us "it's impossible" but here it shows up! Anyone who is confident and who steadfastly believes they know the answer, IMHO, is just showing their ignorance since we haven't ever seen a disaster of this magnitude interacting with so many other planetary environmental systems and man-made technologies.

What I still don't understand is how the Japanese could have built one of the world's largest concentrations of reactors and SFP's in such a place.

BTW, although I'll blame TEPCo for the initial design and the operations deficiencies, one cannot blame them for their hesitation to act. If what we face is truly unknown, a little (or a lot) of caution may make some sense, especially when their country will be the most affected by their actions.

Enough said. I'm checking out for now to do some other work.

In nuclear power plants, we do inventory by fuel assemblies, sometimes called bundles. The fuel assemblies are made up of multiple fuel rods. Depending on the BWR design, there's from 72 to 96 rods per assembly. At the Fukushima plant, we (at least in my documentation) used 96 as the standard for the number of rods per assembly.

At Fukushima prior to the tsunami, there were essentially four inventory locations for BWR fuel assemblies/bundles:

1. The individual reactor core
2. The individual reactor Fuel Pool (aka as the Spent Fuel Pool or SFP)
3. The Fukushima Facility Common SFP
4. The Air-Cooled Fuel Caskets

People keep forgetting about Central Storage and IMHO that could come to bite us. Six thousand fucking rods in a huge pool and to my knowledge, no one has inspected each one individually yet, but that's another story for another time and ecological disastrous leak.......

There are maybe 10-50 other fuel assemblies and other loose radioactive materials located in other places (transit pools, test lab, QC lab, radiology lab, in transport, etc.) but essentially they are a trivial amount of fuel when compared what's actually in cores and SFP's. That'll have to be cleaned up as well, but what a couple of month's clean-up and a few million dollars among us engineers looking at the macro picture.....LoL

So using the Wikipedia numbers (which are as accurate as any), just reactor 4 has 1331 spent fuel assemblies located in its SFP and 204 new fuel assemblies for a total of 1535 fuel assemblies or using the 96 rods per assembly standard a total of 96 x 1535 = 105,915 fuel rods.

Now that's just Unit 4.

If we take the numbers provided by wikipedia,

http://en.wikipedia.org/wiki/Fukushima_D....

the actual number of fuel assemblies at reactors and in reactor SFP's is:


Location Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6 Central Storage
Reactor Fuel Ass 400 548 548 0 548 764 0
Spent Fuel Ass 292 587 514 1331 946 876 6375
New Fuel Ass 100 28 52 204 48 64 N/A

Totals 792 1163 1114 1535 6375

So if we're going to try to recover just units 1-4 and repair the central SFP we
have

792 + 1163 + 1114+ 1535 + 6375 = 10979 Fuel Assemblies or Fuel Bundles

which represents in the neighborhood of 1,053,984 fuel rods to recover.

That's a lot of nuclear material and we aren't touching units 5 and 6.

Just don't use rods and fuel assemblies/bundles interchangeably unless you use the multipliers. IMHO, although the reactor 3 MOX is a problem, the real problem is taking out the staggering volume of damaged fuel assemblies in the other reactors. I'm going to estimate that just the complete removal (not the cleanup) job may take 10-15 years. I'm also wondering where the hell are they going to dispose of all of this nuclear refuse safely on that island, plus all the other debris that goes along with that.