Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[PietKuip]

So they simply deleted Co-56, Ag-108m & I-134
retested the same sample 18 hours later and
Tc-99m increased from 8.7E04 to 4.8E05 a factor 5
Again a mistaken reading -
give me some time and I will work out the lifetime what they are measuring

The second sample has no trace of Tc-99m

The second column is a revised analysis of the same gamma spectrum. Suddenly the total activity is two orders of magnitude lower. It should be impossible to reconcile both analyses with the same total count rate of their sample...

But they measured that spectrum 10 hours after it had been taken. I agree, those levels of I-134 were impossible in a sample that was so old. Maybe they extrapolated small signals back to the time of sampling, multiplying "noise peaks" with 65000 ??

The third columns is from a new spectrum of the same sample. The fourth column is from a new sample.

 

[jlduh]

Joe Neubarth:

Anybody who has ever walked along the sea shore knows that when a wave washes ashore the in rushing water can (because of inertia) go higher up the shore than the initial wave height.

Yep, this leads to the difference between the "run up" and the "wave height", this schematics is self explanatory:

http://www.netimago.com/image_183063.html

Interesting also, it seems the highest run up the 11th March has reached more than 23 meters at Ofunato. And also of interest it has been almost 15 meters at Onagawa port, (don't know at Onagawa nuclear plant). You can see this in the document below, and observe that the variations are large over local configurations on the coast (one can then ask what kind of accuracy limits we can get from the models used to calculate safety risks...).

http://sendai.hmdc.harvard.edu/portal/other_distro/PARI_Field_Survey_02.pdf

 

[83729780]

something to keep an eye on: pressure in RPV #1 is rising once again:

Reactor pressure
(A) 0.374MPaG, (B) 0.416MPaG (27th 09:00)

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1301226468P.pdf

compare to:

(A) 0.365MPaG, (B) 0.389MPaG (26th 21:00)

(A) 0.351MPaG, (B) 0.380MPaG (26th 13:00)

(A) 0.376MPaG, (B) 0.360MPaG (26th 09:30)

(A) 0.353MPaG, (B) 0.360MPaG (26th 05:00)

(A) 0.338MPaG, (B) 0.338MPaG (25th 18:30)

why?

 

[RealWing]

RealWing,

Since you a a former Nuclear Power Plant (NPP) manager, do you or did you use virtual simulator(s) which would show various parts of the reactor, where samples would be taken (under normal circumstances) for training purposes, and in this case general knowledge ? Using terms such as http://www.google.com/url?sa=t&sour...q431mjUA&sig2=Jkr2XAn9Jec3DGUZVjZ0MA&cad=rja", "as low as reasonably achieveable", threw me for a second, but with google, not for long. Screen shots of various parts of the structures involved would greatly aid those attempting to prepare and rehearse the difficult tasks that lie ahead. Are these tools available to those closest to the crisis ? I realize you may or may not know but I thought I would put this out there in case someone following this thread can answer the question. The people addressing the crisis need all the tools they can afford themselves of, and to add the pressure of the world watching them, I can't even begin to imagine what they are going through as they analyze and face each new challenge.

Rhody...

We didnt have virtual simulators for this. We had pre-designated normal and emergency sampling points and operators and chem techs were obviously trained and qualified on these. This was all assuming events that were "design basis events" and in later years for some analyzed "beyond design basis events". What is occurring in Japan is outside of any analyzed event
Many plants had made virtual plant tour videos of normally inaccessible parts of the plant (eg in a BWR, many areas in the turbine building are inacessible or have restricted access when the plant is operating) for work planning and modification purposes. I do not know if the Japanese utilities had these or not. (It has been many years since I've been in a Japanese reactor!)

 

[Reno Deano]

Spent fuel pools contain things other than intact fuel bundles: damages fuel rods, highly irradiated RPV QC coupons, used incore detectors, irradiated reactor internals, etc., and most plants store their Pu-Be neutron calibration sources on the spent fuel pool deck or the turbine building for ease of calibrating instruments at various distances. All of these (except the Pu-Be shielded source) could be sources of various radionuclides.

 

[AntonL]

OffTopic: Political fallout in Germany

In today's two German by-election the Green Party had huge gains
4.6% --> 15.4%
11.7% --> 24.2%

 

[rmattila]

I apologize for taking up a topic already discussed thoroughly on this thread, but there's one thing I've been trying to find an answer to, thus far with no success:

As far as I understand, the US plants with Mark I containments were at some point of time refitted with what is called a "hardened venting", mentioned e.g. http://www.scribd.com/doc/51291366/Report-BWR-Mark-I-Containment-03192011-2 , page 10). Would anyone have any idea, whether the plants in Fukushima Dai-ichi had anything equivalent, or was the venting of containment steam attempted e.g. through pipe lines designed just for changing the atmosphere from air to nitrogen under normal pressure/temperature conditions?

 

[rhody]

We didnt have virtual simulators for this. We had pre-designated normal and emergency sampling points and operators and chem techs were obviously trained and qualified on these. This was all assuming events that were "design basis events" and in later years for some analyzed "beyond design basis events". What is occurring in Japan is outside of any analyzed event
Many plants had made virtual plant tour videos of normally inaccessible parts of the plant (eg in a BWR, many areas in the turbine building are inacessible or have restricted access when the plant is operating) for work planning and modification purposes. I do not know if the Japanese utilities had these or not. (It has been many years since I've been in a Japanese reactor!)

Thanks RealWing,

As you stated, "outside of any analyzed event" must be really frustrating for you, Astronuc and other experts in this thread. One would hope, but not expect the general public to understand. I never am failed to be amazed at critical moments in history, the Apollo 13 rescue effort comes to mind, how the best minds can improvise solutions to seemingly impossible situations. I hope history repeats itself here. I hope that all necessary expertise will be brought to bear to relieve the short term crisis and to come up with a long term solution.

Rhody...

 

[KateB]

Regarding the TC-99m sample and the apparent practice of extrapolating back to the time of the sampling as indicated in TEPCO explanation

Using a 1/2 live of 6.02 hours
8.7E04 -- 10h --> 5.57E04
4.8E05 -- 28h --> 1.19E04

assuming that 5.57E04 and 1.19E04 are the actual lab readings
then one can calculate a half life of 11.34 hours

1.057E06 --- 10h --> 5.57E04 -- 18h --> 1.19E04

What isotope has an half life of 11.34 hours ?

could it just be variance in the samples? I am also wondering about the Ba-140. It increased in the new testing, and I wonder if the size is within a normal margin of variability? Ba-140 is a direct fission yield, as far as I understand.

 

[|Fred]

Spent fuel pools contain things other than intact fuel bundles: damages fuel rods, highly irradiated RPV QC coupons, used incore detectors, irradiated reactor internals, etc., and most plants store their Pu-Be neutron calibration sources on the spent fuel pool deck or the turbine building for ease of calibration instruments at various distances. All of these (except the Pu-Be shielded source) could be sources of various radionuclides.

Thank you for this input, that gives some insight on non purely theoretical fact

 

[timeasterday]

Some video taken Sunday: http://peevee.tv/v/84w992

A few screen grabs from the video here: http://mainichi.jp/select/jiken/graph/20110327_2/

 

[RealWing]

It is maybe useful to go back to the TMI event, which is the only large scale partial core melt due to lack of cooling. It does give some insight into how rapidly the core can start slumping/melting and the reactivity effects. (TMI was a PWR, but core response would be generally similar to a BWR)
For example, some quotes from the Vessel Investigation Report http://library.iit.edu/govdocs/resources/NUREGCR6197part02.pdf

"PHASE 2 (100-174 minutes)
During this period, interactions between melted cladding and structural materials resulted in eutectic material flowing down through the central region of the core until it reached the liquid/steam interface where it solidified, forming the lower supporting crust. Analysis revealed that the lower crust was a Zr-Ag-In-Fe-Ni metallic mixture.5 Zircaloy cladding and Inconel grid spacers most likely formed the first eutectics. Stainless steel control rod cladding would melt when temperatures exceeded 1,427°C. The cladding may also have been breached due to interactions between the stainless steel cladding and molten zircaloy, since the materials form relatively low temperature eutectics. After cladding failure, molten Ag-In-Cd control material with a melting temperature of 827°C would flow down into the crust. Increased fuel rod temperatures would eventually lead to fuel melting.

Phase 4 (224 to 226 minutes)Some control material and quenched, fuel-bearing ceramic material apparently relocated to the lower head prior to 224 minutes. However, the majority of the ceramic material that was deposited on the lower head relocated from the core to the lower head beginning 224 minutes after reactor scram. Debris relocation was completed in approximately 120 seconds. The relocation was substantiated by a sharp increase in pressure and by the increase in SRM count rate"

Note the 120 seconds time frame and the increase in the "SRM count rate" The SRM is the Source Rate Monitor which is a low range fission counting device. This indicates that there was an increase in the fissioning process, (but it was nowhere near going critical.)

There has been several posts about the possibility that the reactor could achieve criticality again and my assessment is that it is possible although unlikely. If the fuel geometry is in the right configuration with some water as moderator and with insufficient poison in the water (eg boron) or the absence of control rod blades, then it could go prompt critical. That is why they are doing whatever they can to ensure boron is being added to any coolant going into the core.

The worst case event is for one (or more) reactors going critical without any control on the power increase. Having said that, BWR's -as designed- are inherently stable (ie as power increases, reactivity decreases), however I have no idea how they behave if the core geometry changes due to melting of the fuel pencils.

 

[83729780]

Some video taken Sunday: http://peevee.tv/v/84w992

I hope 3:45 to 3:47 settles the corium vs. insulation debate (even though the footage is from #3).

 

[havemercy]

I hope 3:45 to 3:47 settles the corium vs. insulation debate (even though the footage is from #3).

Could you explain that please ? (ok, thanks for the response below ;)

 

[Astronuc]

I apologize for taking up a topic already discussed thoroughly on this thread, but there's one thing I've been trying to find an answer to, thus far with no success:

As far as I understand, the US plants with Mark I containments were at some point of time refitted with what is called a "hardened venting", mentioned e.g. http://www.scribd.com/doc/51291366/Report-BWR-Mark-I-Containment-03192011-2 , page 10). Would anyone have any idea, whether the plants in Fukushima Dai-ichi had anything equivalent, or was the venting of containment steam attempted e.g. through pipe lines designed just for changing the atmosphere from air to nitrogen under normal pressure/temperature conditions?

My understanding is that Mk I do not have hydrogen recombiners - and I don't know if any have been retrofitted. I believe Mk II and Mk III do.

 

[warren_c]

I just want to thank every one who has contributed to this thread especially the PF mentors and those who have worked in the industry. I have learned a lot from all of your knowledge and I appreciate that most of the discussion has been fact based.

Thank you all. I wish the best for Japan and hope they get the situation under control soon.

 

[RealWing]

My understanding is that Mk I do not have hydrogen recombiners - and I don't know if any have been retrofitted. I believe Mk II and Mk III do.

I believe you are correct- The realtively small MK-I containment systems rely on nitrogen inerting to ensure there is a low risk of H2 explosions and the NRC accepted this in the 1980's. Powered H2 recombiners may still have been retrofitted, but withiout any power - they did nothing.

 

[Astronuc]

I think there is nitrogen in the drywell, but not on the reactor floor.

At Fukushima, it was not by design that the H₂ went into the volume above the reactor building floor. Apparently the venting system duct work (or somewhere else) ruptured/leaked. The H₂ and steam should have gone up the stack.

The point to be emphsized here is that the event is well BEYOND design basis - the combined effects of earthquake and tsunami (greater than design), the station blackout, and then the injection of seawater and boric acid.

You bet other plants are now looking at DBE and combined effects of natural phenomena, and their EOPs.

TVA is already looking at their units from a worst scenario.
http://www.bloomberg.com/news/2011-03-25/tva-plans-more-catastrophic-scenarios-after-japan-official-says.html

 

[Ivan Seeking]

They were just hit by another quake, about a 6.5, with a [small] Tsunami warning that affects the plant. Hopefully this won't make things worse.

 

[RealWing]

I think there is nitrogen in the drywell, but not on the reactor floor.

At Fukushima, it was not by design that the H₂ went into the volume above the reactor building floor. Apparently the venting system duct work (or somewhere else) ruptured/leaked. The H₂ and steam should have gone up the stack.

The point to be emphsized here is that the event is well BEYOND design basis - the combined effects of earthquake and tsunami (greater than design), the station blackout, and then the injection of seawater and boric acid.

You bet other plants are now looking at DBE and combined effects of natural phenomena, and their EOPs.

TVA is already looking at their units from a worst scenario.
http://www.bloomberg.com/news/2011-03-25/tva-plans-more-catastrophic-scenarios-after-japan-official-says.html

Both the dry well and wet well are interted with N2 - but not the reactor floor.

Agree about DBE events and the already analyzed beyond DBE events- we need to rethink this whole issue - particularly for older reactors. The new "advanced" reactor designs have what appears to be several passive cooling systems that do not rely on any power.

Just like TMI and Chernobyl - unfortunately it takes an tragic event such as this one to make all us engineers and plant operators look hard at the lessons-learned and act on them.

 

[TCups]

Could you explain that please ?

You almost had to be there. It was the beginning of the analysis of the photos coming out of Fukushima, starting with this still photo of the north wall of Bldg 4 after a fire and explosion, and the interpretation that there was a tongue of "something" hanging out of the side of Bldg 4 somewhere around post #500-600. There was debate regarding whether this was insulation or corium. The annotations in black letters were my own observations, added to the photo, and at that point in time there was speculation on my part that the SFP was on the north side of the Bldg. It wasn't

see:

http://i306.photobucket.com/albums/nn270/tcups/r735227_5964756.jpg

The new video is interesting. Notice the drywell cap in the northeast corner of Bldg 4 in the new video?

 

[Texan99]

This http://bravenewclimate.com/2011/03/13/fukushima-simple-explanation/" claims that the replacement generators couldn't be made to connect to the existing system in time:

So mobile diesel generators were trucked in. . . . This is where things started to go seriously wrong. The external power generators could not be connected to the power plant (the plugs did not fit). So after the batteries ran out, the residual heat could not be carried away any more.

 

[Astronuc]

You almost had to be there. It was the beginning of the analysis of the photos coming out of Fukushima, starting with this still photo of the north wall of Bldg 4 after a fire and explosion, and the interpretation that there was a tongue of "something" hanging out of the side of Bldg 4 somewhere around post #500-600. There was debate regarding whether this was insulation or corium. The annotations in black letters were my own observations, added to the photo, and at that point in time there was speculation on my part that the SFP was on the north side of the Bldg. It wasn't

see:

http://i306.photobucket.com/albums/nn270/tcups/r735227_5964756.jpg

The new video is interesting. Notice the drywell cap in the northeast corner of Bldg 4 in the new video?

I the drywell cap is on the NE side, I would expect that the SFP is on the south side of the building.

 

[AtomicWombat]

Actually they garnered a heck of a lot of information from Chernobyl and Three Mile Island. AT Chernobyl, the Lava that was generated from the melt down actually flowed through pipes under the reactor and out onto a basement corridor floor. Photos are available all over the Internet, but the easiest one to locate is a Wiki. Three Mile Island had accumulation at the base of the reactor vessel. That mass was analyzed for content and it consisted primarily of Zirconium and Uranium with far smaller amounts of Steel, Nickle (Inconel), and Chromium. When I read that report I was wondering what happened to the control rods. It turns out the Boron (If the control rods have melted) eventually becomes Boric Acid in solution. As the Japanese were pumping sea water into the reactor, they were diluting the Boric Acid and it was flowing out into the building. Do that long enough, and you can make your corium glow with numerous fissions, especialy if it started out as an old core operating at a high rate of power when the troubles began.

Thanks Joe,

I've posted photos of "corium" before:
https://www.physicsforums.com/showpost.php?p=3198702&postcount=580"

Five different types of corium were discovered at Chernobyl, perhaps emphasising its tendency to separate into phases:
http://en.wikipedia.org/wiki/Corium_(nuclear_reactor)#Chernobyl_accident"

My impression was that at Chernobyl, with the exception of the initial firefighting, water was not heavily used to contain the situation, mainly due to fears of a steam explosion when the corium melted through to the basement.
http://en.wikipedia.org/wiki/Chernobyl_disaster#Steam_explosion_risk"

 

[Astronuc]

This http://bravenewclimate.com/2011/03/13/fukushima-simple-explanation/" claims that the replacement generators couldn't be made to connect to the existing system in time:

That's one problem I heard about with someone with connections to Japan.

I wonder it they couldn't splice cables - or does that imply the wrong voltage?

Next time - have compatible backup generators, and don't put EDGs and fuel supply oceanside - especially not when the coast is near a major subduction zone.

And apparently, since 1990, there has been one mag 7+ earthquake between Iwaki and Tokyo, near the coast.

 

[TCups]

This http://bravenewclimate.com/2011/03/13/fukushima-simple-explanation/" claims that the replacement generators couldn't be made to connect to the existing system in time:

In medicine, after a major traumatic injury, the first hour is called "the golden hour". It is the critical time when heroic efforts to stabilize the patient, maintain an airway, replace lost blood, etc. are most effective -- before body functions start to shut down. After the disasters, the quake and the flood, it sounds like Fukushima may have had a "golden hour" -- a very short interval where the right intervention might have dramatically changed the course of events. How sad it would be if it was technology as basic as "a different type of plug" that was the "nail", as the child's story goes -- "for want of a nail the horse was lost", etc.

It would be hard for me to imagine those first minutes and hours. Power failing. No phone service. The tsunami hit. The generators go and the operators look on in horror as things go horribly wrong.

As I posted earlier -- a helicopter pad and a universal emergency power connection interface might have made for a very different outcome.

I also remember the story of TMI having only one phone line in the control room and the operators desperately trying to call for assistance, but the line was busy much of the time by people calling into see what was going on.

Hindsight is usually 20/20, and often, it is the simple stuff that leads to failures.

 

[Rational Deb8]

Hi folks,

I'm new here, first post. I'm hoping that RealWing or other experts here might be able to help with a few questions.

First, it seems that they've recovered CAMS readings on the drywell and suppression chamber. I'm interested in the significance, if any, but have no idea what normal operating CAM rad levels would be on BWR drywell, or what levels would be expected 15 days post scram (or even 15 days post normal coast down). I feel like an idiot, because I've lost the link (still have the pdf page up) to provide to you all - would have been probably either NISA, TEPCO, METI, or JAIF pdf status report... They're showing:

CAMS

Unit 1 D/W: 3.46 ×10e1Sv/h
S/C: 2.22×10e1Sv/h
(As of 9:00, March 27th)

Unit 2
D/W: 4.16×10e1Sv/h
S/C: 1.41×10e0Sv/h
( As of 9:00, March 27th )

Unit 3
D/W: 3.37×10e1Sv/h
S/C: 1.31×10e0Sv/h
(As of 10:10, March 27th)

I don't suppose anyone here knows of a good source for BWR typical instrumentation normal operating ranges, and charts or spot tables of what would be expected for the for a few days/weeks after scram (ideally), or even after normal shut down?

Thanks in advance!

 

[83729780]

Could you explain that please ?

days earlier (page 26 or so) there was discussion as to what the molten material here was (insulation? corium?):

in the new video you can see a similar formation oozing over a wall (3:45 to 3:47)

looks rather innocuous IMHO

 

[Joe Neubarth]

Thanks Joe,

I've posted photos of "corium" before:
https://www.physicsforums.com/showpost.php?p=3198702&postcount=580"

Five different types of corium were discovered at Chernobyl, perhaps emphasising its tendency to separate into phases:
http://en.wikipedia.org/wiki/Corium_(nuclear_reactor)#Chernobyl_accident"

My impression was that at Chernobyl, with the exception of the initial firefighting, water was not heavily used to contain the situation, mainly due to fears of a steam explosion when the corium melted through to the basement.
http://en.wikipedia.org/wiki/Chernobyl_disaster#Steam_explosion_risk"

At Chernobyl they found (or so I read years ago) that the water only seemed to accelerate the burning process in the pile. Could be the water was dissociating and providing oxygen to the burning Uranium and Graphite.

 

[RealWing]

Hi folks,

I'm new here, first post. I'm hoping that RealWing or other experts here might be able to help with a few questions.

First, it seems that they've recovered CAMS readings on the drywell and suppression chamber. I'm interested in the significance, if any, but have no idea what normal operating CAM rad levels would be on BWR drywell, or what levels would be expected 15 days post scram (or even 15 days post normal coast down). I feel like an idiot, because I've lost the link (still have the pdf page up) to provide to you all - would have been probably either NISA, TEPCO, METI, or JAIF pdf status report... They're showing:

CAMS

Unit 1 D/W: 3.46 ×10e1Sv/h
S/C: 2.22×10e1Sv/h
(As of 9:00, March 27th)

Unit 2
D/W: 4.16×10e1Sv/h
S/C: 1.41×10e0Sv/h
( As of 9:00, March 27th )

Unit 3
D/W: 3.37×10e1Sv/h
S/C: 1.31×10e0Sv/h
(As of 10:10, March 27th)

I don't suppose anyone here knows of a good source for BWR typical instrumentation normal operating ranges, and charts or spot tables of what would be expected for the for a few days/weeks after scram (ideally), or even after normal shut down?

Thanks in advance!

Good question!

I've been watching the Suppression Chamber or S/C (Torus area) for some time since it gives you some indication of fuel damage. When the reactor vessel was vented to relieve pressure (and allow water injection), it vents into the S/C under water. If it was just steam, the radiation levels would be quite low. - but the levels are quite high instead.

eg Unit 1 is now 22.2 Sv/hr or 2220 rem/hr or ~36rem/min. In other words , in less than 1 minute, a worker would receive their emergency dose for a year (assuming my calcs are correct)