Japan Earthquake: nuclear plants

Reno Deano

The Torus is design for steam water suppression during a LOCA. Venting of gas from the Dry Well and RPV is via other systems.

See: http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf

romillyh

Re M Bachmeier comments in Post 830:

For anyone who's in any doubt about what a strong ground wave looks like, how fast it travels, and what it can do to objects of any weight, it's worth looking at a rather grisly video of an underground H-bomb test for Project Cannikin in Amchitka, Alaska. Blast was magnitude 7.0 on Richter scale. Detonation was 2 km below surface. Video is just 0:47 long.

http://www.youtube.com/watch?v=qp6aZIhHiRE

Imagine this going on for 5 mins! Are the Fukushima plants "anchored" directly to the ground/rock (i.e. they take the full force of the bucking), or do they have some kind of disconnect to absorb strong ground movements, as one understands quake-"proofed" buildings in Japan do?

Re 5 mins: From memory, seismic trace of the main M9 quake as recorded by the British Geol Survey in Edinburgh can actually be seen continuing for around 50 minutes, though this was recorded the other side of the planet (echoes, reverbs?) and the after-events obviously tail off in magnitude after the main shock.

romillyh

And sorry, I should add to that last message (836) that I saw somewhere that the force of the quake at Fukushima -- what actually hit it, as opposed to the magnitude 9 over the epicenter -- was around M7.

donvance

I bought my Iodide tablets for me and my family! Being prepared is important! Do not be fooled by the Iodate tablets, Iodide is the way to go! They are good for a 14 day protection!
Get some everyone and be prepared, or just spend 1000's and build yourself a fallout shelter???

AntonL

Under 'normal' circumstance steam is vented from RV into the torus and bubbled through the hopefully cool water so condensation can take place and CV pressure should not rise only the torus water level would rise.

Under 'meltdown' condition steam and H2 is vented from RV into the torus. If CV pressure rises CV contains steam and compressed H2 and N2 - no O2.

Torus is part of the primary containment and in later models no longer used as in the Mark 3 reactor
Fukushima Daiichi Units 1 to 5 are Mark 1 and Unit 6 is a Mark 3


When a melt-down takes place you want no water near it otherwise you will have a steam explosion.
The torus, in mark 1, and meltdown containment in mark 3 keep the water well away from the hot meltdown

Borek

Taking them without a reason is dangerous for your health. I guess someone made a perfect deal selling you something you don't need.

Reno Deano

Iodine levels at 100 times background is not dangerous at all. BTW, I assume your doctor told you about the possible serious side affects of taking KI? Can you imagine being in a underground shelter during a 9 magnitude earthqake?

The off site contamination is being blown way out of proportion. They should be discussing the actual relative low risks of eating foods with only slightly higher than background radionuclide contamination. Tens of thousand of nuclear works and bomb testing fallout survivors that received thousands of times hight doses, did not suffer any serious consequence over their exposures. Very low concentrations of long live primordial Uranium is present in most of our water and food stuffs anyway.

TCups

OK, so . . .

1) In unit 4, it is beyond dispute -- if the explosion was a hydrogen explosion, then the hydrogen came from spent (and possibly un-spent) fuel rods in the SFP, not in the empty RV.

2) In units 1, 2, 3, if hydrogen exploded, it would need oxygen and therefor, the source of the explosion was not within the RV

3) In units 1, 2, 3, hydrogen could have been and was likely to have been produced by both an overheating reactor core in the RV and by overheated fuel rods in the SFP.

4) With loss of cooling, the hot cores in the reactor were, IMO, the more likely first source of trouble and first source of hydrogen production (correct?)

5) If a RV's steam and hydrogen were vented into the drywell torus, bubbling through the suppression pool of cool water, would the hydrogen then be in an atmosphere of air or of nitrogen, flooding the torus?

6) Is it possible for hydrogen (or hydrogen and oxygen) to have accumulated in the upper portion of the drywell containment, near the drywell cap, under pressure (for example if the normal venting system -- ducts, pipes -- had been damaged?

7) Except for Unit 4, why IYO, is the source of exploding hydrogen more likely from the SFP than, somehow, from the RV via leakage into the primary containment?

8) Is it not possible or even likely, that whichever came first, if an explosion occurred in Unit three, then both accumulated hydrogen in the upper building, external to the primary containment, and hydrogen leaking from under the drywell cap, would have ignited and led to explosions both inside the drywell containment and inside the upper building structure?

9) Why do you think the SFPs were the primary source of all explosions?

M. Bachmeier

Yes, I think it's a 'miracle' that there haven't been more attempts to advance questionable remedies, concoctions, 'medicines' and alike associated with fears of radiation. What do you think????????????

Sorry for being off topic... I just couldn't help myself.

AntonL

By demonstration of Unit 4

AntonL

Now German tabloid Bild reports that unit 1 reactor temperature has risen to 380 to 390 degrees C, normal operating temperature is 300 degrees C, for days we had no temperature indications. I conclude that batteries must be recharging so control room function is coming online.

TCups

But Unit 4 was unique in that the unspent fuel from the core was removed from the core and put in either the SFP (most likely) or as some suggested, in the equipment pool. Either way, the rods in Unit 4 wold have been "hotter", and yet, the explosion in unit 4 came last. That could have been a difference precipitated by earlier or greater loss of coolant in Units 1, 2, and 3. Possible, but not entirely likely, IMO -- unless coolant "borrowing" was somehow in play.

Arcer

At a rough count there seems to be about 30 to 40 of those rods scattered about which is about a full fuel rod assembly. Most of them seem to have fallen and come to rest as a loose bundle with the rods almost in parallel.

That's as if they'd slid out together through a hole in the building wall. With the cask lorries parked outside it's possible they're new fuel rods decanted out of an open transport cask during inspection after delivery. Maybe a transport cask overturned? Or a new fuel rod storage canister might have overurned and spilt part of its fuel rod contents. It doesn't explain how the wrapping bands around the assemblies might have broken but maybe they're not as tightly bound together as they appear in photographs.

It's speculation of course.

JUrban

Spent fuel pool watering method

Fluctuating radiation and isotope levels are making ground work dangerous and slow, with a potential to completely cease work (of which there appears considerable cooling system work) and ground based watering, at least for some time.

Discharged water from ground based watering trucks substantially disperses on its course over building walls up to about 150 feet in height, and suitable positioning of watering trucks is also limited.

Water volume needed to mitigate each spent fuel pool is substantial, in the hundreds of thousands of gallons, which, along with counteracting pool water loss, necessitates sufficient and reliable gallons per minute filling pool fill rate (of water actually received by pools).

Apparent lack of experimentation to find a more effective watering method (perhaps due to lack of anticipation and thought in nuclear industry for present situation) is concerning.

Thermal imaging (Figure 1) reveals rising temperatures likely in spent fuel pools, as well as critical planning information for placement of new watering method.

Critical to re-establish water in spent fuel pools, which hold most of the nuclear material, the material susceptible to break down over time without water and has no containment if aerosolized.

Based on careful analysis, most effective watering method (of many) involves deploying hose with grappling hook like structure at outflow end, to be caught at top of building structure near a hotspot location.

System is best deployed by helicopter lift operation, and due to relatively low level of precision needed and natural stabilization (see below), 1) lift cable can be in excess of 500 feet (long line lifting), optionally without nearby vertical reference ground spotter, and 2) completion of lift operation, during which building is approached from air, can be done in minimal time (minutes), substantially limiting radiation dose of air crew (JSDF carried out helicopter watering operation on 17th with short line; that day about 88 millisieverts per hour was measured at 300 foot elevation and about 4 millisieverts per hour at 1000 foot elevation).

In simplest deployment method, for completion of lift operation, hose is laid over side of building (Figure 2A) with outflow end (having grappling hook structure, not necessarily drawn to scale) lowered into area above spent fuel pool/hot spot (Figure 2B). Lift line release and helicopter departure can then occur.

When water is pumped through the inflow end of the hose at a relatively safe location (assume 1 mile hose length for calculations), the weight of the water in the section of hose ascending up the wall will create hose tension that pulls the outflow end back (Figure 2C), causing the relatively simple steel grappling hook structure to become caught on surrounding structure and serve as an anchor. Assuming an ascending hose length of 150 feet, for a 2 inch diameter hose the water weight is about 200 pounds, or for a 4 inch diameter hose the water weight is about 800 pounds. It's seen that such weights are similar to what conventional grappling hooks experience.

In simplest deployment method, at beginning of lift operation a sufficient length of hose, such as lay-flat discharge/irrigation hose (Figure 3) often encountered on the order of miles in length, is prepared at a safe staging area for lifting (Figure 4A). During air transport the entire hose section can hang from lift cable (Figure 4B), ready for imprecise laying of the hose (Figure 4C), likely followed by some pulling/dragging near the end of the lay to achieve good longitudinal placement. Irrigation hose can have excellent abrasion and puncture resistance. By laying a relatively long section of hose, intermediate coupling operations on the ground can be avoided, although are also a viable approach if radiation levels permit.

A benefit of this lay/minimal pull deployment method is that the grappling hook at hose outflow end is naturally stabilized for its placement. In particular rotational and for/aft motion is stabilized, with also some side to side stabilization due to lateral friction and hose constraint with debris on the ground.

For a 100 gallons per minute flow rate through 1 mile of hose, a 4 inch diameter hose will have only about a 12 psi pressure drop, with greater drops for smaller hoses. Assuming a 150 foot hose rise over the building wall, an additional 65 psi of pressure is added for pumping to overcome, which is well within reasonable range. Medium duty lay flat irrigation hose is typically rated for 150 psi.

Although spring/pull-line directional control of water discharge is possible, it's likely sufficient to simply implement a water outflow pattern that is somewhat divergent to compensate for any misalignment with storage pool, considering the high flow rate effectively discharged directly into the area, as apposed to attempting to discharge from outside of the building and near ground level as has been done thus far. Also, discharge distance effectively adjusted by varying pumping pressure.

In the case of buildings with intact rooftops (such as unit 2) yet inability to water spent fuel pools due to excessive radiation levels, a hole of sufficient size can be punctured above the spent fuel pool area and a single hook metal structure with hose can be deployed by air lift into the puncture to then catch upon pumping (Figure 5, again not necessarily drawn to scale) as described earlier. All intact reactor buildings have already lost negative gauge pressure (including units 5 and 6 in which intentional vents were made in the rooftops).

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Arcer

Very interesting that units 4 and 2 had explosions withing 6 minutes of each other both on the 15 March.

Arcer

http://www.youtube.com/user/KurtsFilmeVideo#p/u

Speculation again but it's possible that those bits of roof (steel) still remaining on building 3 are actually being supported by the gantry crane. Although against that I remember there was opinion that the crane might have landed on a low level building adjoining the north side of building 3.

And at exactly 2.50 into the video could that long green object lying on the ground be a green gantry crane blown out of one of the buildings likely 3 as the most explosive. So three alternatives for what happened to the gantry crane?

AntonL

filling of unit 4 SFP by concrete lifter


I am amazed by the protection suits, two piece, open collar, construction helmet ...
Compare to clothing in this video http://www.youtube.com/watch?v=apryc...feature=relmfu

and workers/inspectors then drive home in their cars, I presume after a hosing down, but is that effective?