Japan Earthquake: nuclear plants Fukushima part 2

[Sotan]

I have to make an important correction.
Reading Rive's reply I couldn't help thinking how that reported volume of water used to be 5,000 m3 a few months ago and now is close to 11,000 m3 - such a rise didn't fit with the idea suggested in that reply, which is that they have to keep that water level in the basement pretty well balanced and always watch the groundwater level...

So I went and studied some past reports and I realized I made a big error in translation: those numbers, be it 5,000 m3 or 11,000m3 now, are NOT the volume of water accumulated in the basement, but the total volume of water pumped, in time, from that basement into other places, mainly towards the water treatment facilities. As such, it is only normal that this number increases every single day (by several tens of m3).

I deeply apologize for this mistake. I was under the false impression that huge amounts of highly contaminated water keep gathering in the basement... And thank you Rive for pointing me into the right direction.

P.S. Studying past reports I also understood that changing a flow of reactor cooling water by 1 m3/h or even more has happened many times in the past, so indeed that is not a significant change either.

 

[nikkkom]

I don't understand this entire water situation.

The endless pouring of water into ruined reactors. What they are trying to achieve - rust all steel to dust and dissolve the basement for good?

The ever-growing tank farm.

The ever-broken ALPS. Gosh, you would think that water purification isn't rocket science!

 

[Hiddencamper]

I don't understand this entire water situation.

The endless pouring of water into ruined reactors. What they are trying to achieve - rust all steel to dust and dissolve the basement for good?

The ever-growing tank farm.

The ever-broken ALPS. Gosh, you would think that water purification isn't rocket science!

Well the water keeps the debris cooled. Which provides shielding. It also contains many radioisotopes. It prevents airborne activity. And the constant supply and cooling ensures you don't get boiling, which is a transit mechanism for some radioisotopes.

As for a water cleanup system, I don't know exactly what they are using. Typically in a nuclear plant we use resin for ion exchange. Resin is coated to and held on a septum and the pressure of water entering the ion exchange chamber forces the water past the resin and through the septum. The resin needs to be changed out as it becomes depleted, otherwise low affinity ions will start leaching out of the resin. It's mildly complicated. Because of how the septum works, a loss of pressure results in the resin coat dumping, and the entire chamber needs it's resin replaced which can be a pain (also expensive).

Just some thoughts

 

[nikkkom]

Well the water keeps the debris cooled. Which provides shielding.

There is plenty of shielding already. Many meters of concrete.
Those reactors used to be in operation for years, you know. Operating reactor emits at least 20 times more gammas than even freshly shut down one, let alone one which is shut down for 3 years already.

It also contains many radioisotopes.

No. It washes out isotopes into those many huge tanks.

It prevents airborne activity.

There is a novel method to prevent that, called "make it airtight". Which is not that hard, since containment *was* airtight to begin with, and there can't be that many atmospheric leaks in it now.

And the constant supply and cooling ensures you don't get boiling, which is a transit mechanism for some radioisotopes.

What boiling? It's been 3+ years already! The containment *has* nonzero heat flow through the walls, you know. It *will* lose heat and cool down even if no water is poured in.

Has anyone URLs to recent temperature data for containments?

 

[Hiddencamper]

I'm just going to respond with an anecdote.

Last outage we allowed our reactor cavity to dry out. By allowing dry out to occur, we had a lot of airborne contamination. 20 people had internal contamination (fortunately thanks to our alarms, nobody was exposed to more than 1 DAC). After we filtered containment for a while, we sent 2 guys in portable air packs and full bubble PCs and had them hose down the cavity for a full shift.

When dealing with high levels of contamination, even seemingly innocuous things can result in an uncontrolled spread of radiation.

 

[etudiant]

TEPCO and nikkkom share the same basic aims, get the site off the problem list.
TEPCO has the difficult task of making that happen.
Unfortunately, the site post earthquake and meltdowns cum explosions is riven with leaks and cracks all over, as well as lethally radioactive below ground and significantly contaminated above. To limit the outward diffusion of radioactive water, TEPCO must keep the site water level a bit below that of the surrounding ground water.
Simultaneously, TEPCO must keep on cooling the wreckage, for reasons hiddencamper has articulated above.

TEPCO cannot just recycle the cooling water, because that would hopelessly contaminate the above ground structures and kill the effort to clear out the SFPs. Yet cleaning the water is a bear, because it holds so many different contaminants, including oil, salt, multiple metal compounds and tritium. Even though they are only present in minute concentrations, parts per million or less, they are so radioactive that they must be removed.
ALPS is afaik the first system ever to deal with this broad a range of contaminants. TEPCO will be doing great if they can get it working even half the time. They are installing 3 ALPS trains, once they are up, TEPCO will gradually be able to get on top of the water problem, but it will still take several years.

 

[Gary7]

Has anyone URLs to recent temperature data for containments?

According to the most recent update (May 2nd) it says the temperature of the pressure vessels is

Unit 1 = 19.3 c
Unit 2 = 28.8 c
Unit 3 = 26.1 c

Ambient temperature in Fukushima is around 26 today. Maybe a bit lower at the beach.

http://www.tepco.co.jp/nu/fukushima-np/handouts/2014/images/handouts_140502_06-j.pdf

 

[Rive]

What boiling? It's been 3+ years already!

Unfortunately that does not matter. General used fuel can be moved to dry storage after 3-5 years, but general used fuel has a geometry ideal for heat removal, and even with that geometry, the fuel limit of a dry storage cask is much less than a core.

Right now, the geometry of the fuel/core debris is unknown. It's possible (actually, it's quite likely) that the mass of the whole core is melted into a single puddle, with minimal free surface. Without adequate cooling, the possibility of re-melt still cannot be ruled out, even after three years.

The necessity of cooling creates other necessities, which also has consequences. Right now I don't really know a better general approach than what TEPCO is trying.

Th continuous failings of the ALPS implies that it's too complicated. I think they will be forced to try something else for its role.

 

[nikkkom]

ALPS is afaik the first system ever to deal with this broad a range of contaminants.

Not at all.
What do you think French are doing when they need to discharge some water after it was used in La Hague in their reprocessing plant?
I was reading about it. They are quite proud just how tiny little radioactivity manages to escape. Their water and gas purification tech there must be good.

 

[jim hardy]

Right now I don't really know a better general approach than what TEPCO is trying.

Th continuous failings of the ALPS implies that it's too complicated. I think they will be forced to try something else for its role.

Amen to both statements.

Known water throughput and temperature measurement tells how much heat is being handled.


ALPS?

Before there was a high tech there had to be a low tech.

KISS principle endures because it works.
Old fashioned distillation might be viable as pretreatment for ALPS.
With so many coal plants being shut down there's plenty of heat exchange equipment on surplus market right now.

This print adorned the wall in our maintenance shop.

courtesy this gallery : http://galleryone.com/fineart/christensen/CHRLO1.html

old jim

 

[Rive]

Known water throughput and temperature measurement tells how much heat is being handled.

To know the heat output alone is not enough. The CPU in my computer has only 40-50W power consumption, but it would cook itself within seconds (2-300c degree) if left without its heatsink (cooling surface reduced from some 100cm2 to 5cm2, no airflow).
You need to know the exact geometry and circumstances.

Ps.: an expert would be able to calculate a heat output from the core load details and time spent from 'shutdown'. There was some such calculations regarding U4 pool heat output. Even the mass of nuclides already removed could be accounted.

 

[jim hardy]

Ps.: an expert would be able to calculate a heat output from the core load details and time spent from 'shutdown'. There was some such calculations regarding U4 pool heat output. Even the mass of nuclides already removed could be accounted.

and, if they're lucky they might be able to figure out where the core is physically located..

 

[etudiant]

Not at all.
What do you think French are doing when they need to discharge some water after it was used in La Hague in their reprocessing plant?
I was reading about it. They are quite proud just how tiny little radioactivity manages to escape. Their water and gas purification tech there must be good.

Afaik, the Fukushima situation is unique because of the breadth of contaminants in the water, not just nuclear fuel leachates, but also oil, hydraulic fluids, sea water etc.
ALPS is multi stage and is about the best that the industry currently can come up with. Toshiba has the system responsibility, with Energy Solutions providing the technical design. France's AREVA did provide one of the initial water treatment system, along with Kurion. ALPS is expected to offer a more comprehensive treatment, good enough to allow the water to be dumped

 

[nikkkom]

Afaik, the Fukushima situation is unique because of the breadth of contaminants in the water, not just nuclear fuel leachates, but also oil, hydraulic fluids, sea water etc.

I don't believe any of those are anywhere near comparable to the water coming out of spent fuel ceramics dissolved by nitric acid (La Hague).

Oil contamination is such a typical problem, there are thousands of units all over the world dealing with that.

Seawater adds metal ions of kinds which are already present in spent fuel.

ALPS is multi stage and is about the best that the industry currently can come up with.

You think so why?

ALPS is expected to offer a more comprehensive treatment, good enough to allow the water to be dumped

So far it offered only delay after delay after delay.

Any double distillator with oil prefilter would do better than that.

 

[etudiant]

I don't believe any of those are anywhere near comparable to the water coming out of spent fuel ceramics dissolved by nitric acid (La Hague).

Oil contamination is such a typical problem, there are thousands of units all over the world dealing with that.

Seawater adds metal ions of kinds which are already present in spent fuel.

.

It may be that France has a better technology for purifying contaminated water, but simply failed to bring it to Japan's attention when Toshiba was waving a blank check to get a solution to the Fukushima water problem.
In any case, none of the normal reprocessing techniques are even vaguely relevant to the problem here, going on a half million tons of grossly contaminated water.
Nuclear fuels live sheltered lives, clad in zirconia, surrounded by ultra pure water. That is not the case for the Fukushima coolants, unique both in terms of the scale of the problem and the diversity of contaminants. ALPS certainly has been a disappointment thus far, but if there is a plausible alternative, it has not been brought forth publicly.

 

[Hiddencamper]

Sorry I don't have the original link (on my work email).

https://drive.google.com/file/d/0B-HOaUJyFtPhSDFGUmhUOW9UbVB5aE5EUEY5dVhCd19HSWRz/edit?usp=sharing

This is a pdf of the NRC's review of the structural/seismic analysis of the unit 4 spent fuel pool. It also includes a discussion of decay heat. They seem to believe at this point, the unit 4 spent fuel pool is entirely capable of being air cooled.

Some good stuff here.

 

[nikkkom]

In any case, none of the normal reprocessing techniques are even vaguely relevant to the problem here, going on a half million tons of grossly contaminated water.
Nuclear fuels live sheltered lives, clad in zirconia, surrounded by ultra pure water. That is not the case for the Fukushima coolants

PUREX reprocessing starts with cutting zirconium tubes up and dropping ceramic pellets of spent fuel into nitric acid bath.

The resulting solution is *several thousand times* nastier than Fukushima's water can possibly be: it emits several million rem/hour!

Any gaseous and vapor effluents from that solution have to be, and are thoroughly scrubbed and filtered by French.

The part of their La Hague plant which deals with said effluents would be laughing if it had to process Fukushima water. It would pass as "slightly contaminated water".

 

[Rive]

PUREX reprocessing ...

The material for 'simple' reprocessing comes from controlled environment. It's content is well known.
In Fukushima the process must start with assuming everything.
It's really a different task.
However this difference does not automatically means that the equipment must be as complex and sensitive as the ALPS.

 

[Sotan]

http://www.tepco.co.jp/nu/fukushima-np/handouts/2014/images/handouts_140515_05-j.pdf
(in Japanese)

It shows some results of the investigation of Main Steam Isolation Valve room (latest operations performed on May 15)

They made holes in the floor of the air conditioning room located right above the MSIV room. Through those holes they lowered a hook to raise the grating, then an endoscope and a pan-tilt camera with lighting.

They found a hole (a crack at a pipe joint?) through which water is flowing. The location is where the D-main steam pipe connects to the MSIV. They describe the size of the water stream as “2-4 pencils wide”. No loss of water was found around A, B, C main steam pipes or the steam drain pipe.

The floor of the room is all covered with water. The water appears stagnant in the Northern side of the room (corresponding to main steam pipes A and B). In the other side of the room, the water on the floor flows towards South. This water flow also suggests that the only hole that let's water escape is the one identified near the main steam pipe D.

Edit: there are some photos and videos here:
http://photo.tepco.co.jp/date/2014/201405-j/140515-01j.html

 

[mscharisma]

http://www.tepco.co.jp/nu/fukushima-np/handouts/2014/images/handouts_140515_05-j.pdf
(in Japanese)

It shows some results ...

This is about Unit 3? Thanks in advance for clarification.

 

[Sotan]

Sorry, yes, it's Unit 3.

(The video is awesome... Even though the camera is dangling, you can actually see water flowing from the crack.)

 

[zapperzero]

And artefacts from the radiation, and water flowing on the floor and lots and lots of rust. I wonder where that came from.

 

[Hiddencamper]

Well that sucks.

So there's one confirmed containment failure point.

We do know that unit 3 had a pretty severe hydrogen explosion. There are theories that there was a lot of containment damage during the hot debris ejection, which may have caused this.

 

[mheslep]

How is it known that the leak comes from containment? Identification of the pipe?

 

[Rive]

They found a hole (a crack at a pipe joint?) through which water is flowing. The location is where the D-main steam pipe connects to the MSIV. They describe the size of the water stream as “2-4 pencils wide”. No loss of water was found around A, B, C main steam pipes or the steam drain pipe.

Thanks for the vid.

As I see there is also a water flow where the big pipes goes through the wall. There is also some rust there.

 

[zapperzero]

There are theories that there was a lot of containment damage during the hot debris ejection, which may have caused this.

Could have been caused by steam explosion, I think. Here's a nice schematic btw:
http://fukushimaupdate.com/wp-content/uploads/2014/01/containmentvessel.jpg

 

[LabratSR]

Factory-made Tank Installation

http://youtu.be/lto8VUCRZfw

 

[westfield]

Could have been caused by steam explosion, I think. Here's a nice schematic btw:
http://fukushimaupdate.com/wp-content/uploads/2014/01/containmentvessel.jpg

ZZ the schematic isn't very helpful tbh.

What Tepco is reporting here is in the "MSIV Room", outside of containment.

Related to this are reports from January and April regarding the U3 MSIV room which I had missed.


http://www.fukuleaks.org/web/?p=12208

http://www.fukuleaks.org/web/?p=12907

This is a more indicative view. (Allegedly U1 but same as U3 as far as the general location of the MSIV room and the HVAC room above it goes). Shows MSIV's inside and outside of containment.)

 

[Hiddencamper]

It looks like a containment penetration or guard pipe is leaking. So this could be a drywell leak or a reactor leak. Considering the reactor is likely breached, any reactor vessel leak IS a containment leak.

The location of the MSIVs is in what is called the "Main Steam Pipe Tunnel" or "Pipe Chase". This is where the steam lines go out, and the feedwater lines come in.

Anyways...looking at this some more:

The steam lines in a BWR have double isolations. There are 4 steam lines in the BWR reactor type at Fukushima. Each steam line has 1 MSIV inside the drywell, and 1 MSIV outside the drywell in the pipe tunnel. The MSIVs are spring loaded, and require air to open against spring pressure. They fail closed on a loss of air (the springs push them closed). De-energizing their air solenoid valves will also vent the air off. The valves are reverse seated, this means the valve seat has the reactor's pressure behind it, helping to push it shut.

If either the inboard or outboard MSIV is closed for a steam line, there should be no leakage. The leakage in the video is in the pipe tunnel, between the inboard and outboard MSIV. However we cannot see the main steam line itself, we only see the containment penetration. The most likely source of the leak is through the containment penetration (the hole in the wall). The Mark I containment design does not support water going all the way up to the main steam lines via containment flood, and it is very likely the MSIVs have remained in their closed position with little to no leakage during the event. This is my best guess though, based on working in similar BWR models.

 

[Sotan]

http://www.tepco.co.jp/nu/fukushima-np/handouts/2014/images/handouts_140527_06-j.pdf
(in Japanese)

A report on the investigation carried out in the upper area of the suppression chamber (S/C) of Unit 1

- A previous investigation done in November 2013, using a floating robot, led to the conclusion that there is a water leak in the upper area of the S/C – in a region designated as X5-E, in the South-East side of the torus. A flow of water was confirmed from the “sand cushion drain”, X-5B, North-West. This time the investigation was aimed to pinpoint the location of the leak, as well as to obtain general visual data.

- A specially developed robot was inserted through a hole that was made in the North-West region, and then sent to take images of the area, while moving along the “out-side catwalk” that goes along the S/C.

- In the X-5E area there is a “vacuum breaking line” which has a “bellow-type expansion joint”, covered with a protective cover, with an exterior diameter of about 800 mm. Water is flowing on the surface of this cover, at the end of the expansion joint on the PCV side. (Sorry for the vague translation, the diagrams in the report may be easier to understand.)

- On page 5, upper left, there is a photo of the other, opposite end of the expansion joint. A water leak is confirmed in the place where a holding bolt used to be mounted, used during the transportation of the joint assembly (the bolt has been removed after the joint has been set in its place).

- No water leak was found in the areas of the vacuum breaking valve, torus hatch, SHC-(shutdown cooling system?) pipes or AC-(air-conditioning??) pipes.

- On page 7 they state, as a conclusion, that the investigation has not indicated “striking” (considerable, significant) water leakage and/or material damages in the area.

- This time they only filmed about half of the circumference if the torus. Tomorrow they plan to continue with the South-East half.

 

[Rive]

Some components we were aware on the early days regarding the rubble on top of U3 can be seen here in operation:
http://photo.tepco.co.jp/index-j.html

For example the 'spanner':

 

[Sotan]

That above is a photo from the opening of Reactor 1 in Fukushima Daini plant.
More info and photos in this report (in Japanese): http://www.tepco.co.jp/nu/f2-np/handouts/j140528a-j.pdf
They started the operation on May 12th and finished on May 27th.
On June 2 they plan to start removing the fuel assemblies and transport them to the common fuel pool.
They also list several issues they discovered upon removing all those lids: friction marks in the contact areas between the concrete hatch and its support; and damages to some of the bolts that hold in place the cover of the bellows mounted between the PCV and the building floor. Apparently 6 bolts were found ruptured, and one broken piece of one bolt is missing (although it cannot get anywhere into the reactor vessel, by construction). They conclude that all these damages found on inspection are not affecting the functions of the facility.

 

[jadair1]

I was wondering how the level of contamination in the exclusion zones for Fukushima and Chernobyl would compare to that of a hypothetical dirty bomb the intelligence agencies say we should all fear so much, when I came across this gem.

From Wikipedia:

"For the majority involved in an RDD incident, the radiation health risks (i.e. increased probability of developing cancer later in life due to radiation exposure) are small, comparable to the health risk from smoking five packages of cigarettes on a daily basis."

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

Doesn't the author see the contradiction in this statement?

Either the risk is small and equivalent to smoking no cigarettes per day, or it is extreme and the equivalent of smoking five packs per day. (This would easily take at least twenty years off the average persons lifespan, I smoked two packs per day and developed mouth cancer at the ripe old age of 51, fortunately they operated and got it all and I have been cancer free for 6 years now.)

Someone on this forum once suggested I should use Wikipedia for a source before asking what he thought was a simple question. It is drivel such as that quoted above why I don't trust Wikipedia.

So I will ask the question here, where there are knowledgeable people who's answers I know I can trust, does anyone here know what the comparables may be.

Yes I know there are many unknown factors such as radiological materials used and dispersion methods etc., but a rough comparison.

 

[Hiddencamper]

Sotan, are the decommissioning the Daini site? (Trying to understand why they are removing all the fuel)

 

[Sotan]

There are people/organizations calling for the decommissioning of Daini too, but after a quick search I couldn't find anything about such a decision having been taken. I will search more.

My impression after reading the last report, where Tepco underlines that "all these damages found upon inspection are not affecting the functions of the facility", is that they are at least planning to have it back working again.