Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130320/index.html The temporary switchboard (on a truck) where the rat died was installed in May 2011. It was scheduled to replace it by a new indoors switchboard by next summer.

 

[LabratSR]

Looks to me like they just didn't use enough duck tape...

http://fukushima-is-still-news.over-blog.com/article-a-mouse-in-the-panel-board-116365910.html

 

[nuclear_jimmy]

According to Tepco, the power blackout of Fukushima plant was caused by a mouse that came in the terminals to have caused a short circuit.

trying to switch the blame to a dead mouse, good luck with that Tepco, it wasn't a design flaw at all.

 

[jim hardy]

That switchgear looks to have flashed over.

I suspect the culprit was one of that mouse's buddies. There should have been nothing left of him. 480 volt makes a loud "BOOM" when it flashes.

 

[nikkkom]

That switchgear looks to have flashed over.

I suspect the culprit was one of that mouse's buddies. There should have been nothing left of him. 480 volt makes a loud "BOOM" when it flashes.

Europe uses 220V as its standard voltage. I assure you from first hand experience that 220V electric shock doesn't do anything close to that.

 

[a.ua.]

Strength damage also depends on the current.
I saw the burning copper thick wire at 36 volts.
And even a 12 volt battery can kill.
If they fall on you from above.

Europe uses 380V as its standard voltage.

 

[Astronuc]

That switchgear looks to have flashed over.

I suspect the culprit was one of that mouse's buddies. There should have been nothing left of him. 480 volt makes a loud "BOOM" when it flashes.

So does 440 volts and about 10 or more amps. I know from personal experience when a ground a hot line. There was a bright blue-white flash, my body went stiff, the wrench (I was using the wrench to close a switch that was supposed to be dead) I was holding flew out of my hand, I flew backwards against the wall behind me, and I could smell burning hair and skin. Needless to say, I felt like I'd been hit with a sledgehammer all over. It took me a few minutes to recover, at which point I got myself out there, back to the office, and told I was taking the rest of the day off.

 

[triumph61]

Europe uses 220V as its standard voltage. I assure you from first hand experience that 220V electric shock doesn't do anything close to that.

Sorry, the StandarD Voltage in Europe is 230/400V (D/FR/AUT/NL/DK)

 

[clancy688]

Sorry, the StandarD Voltage in Europe is 230/400V (D/FR/AUT/NL/DK)

It is now. It wasn't always.

 

[triumph61]

since 1987

 

[Bandit127]

I have a rather severe message from an admin in my inbox for straying off topic (in another thread)...

Based on that I am motivated to request that we get back on topic. Please.

And apologies to those that have had electric shocks and want to compare notes - perhaps a new thread would be appropriate?

 

[LabratSR]

Apparently recent video. Looks like they've hung something on Unit 3's wall(s). I don't recall hearing about it but I may have missed it

http://youtu.be/EGkuCfNvrGA

 

[Joffan]

Apparently recent video. Looks like they've hung something on Unit 3's wall(s). I don't recall hearing about it but I may have missed it

http://youtu.be/EGkuCfNvrGA

I believe they have built a platform all around unit 3 building at the refueling floor height; the strips are probably draped covers to protect the scaffolding. The cranes working to clear stuff from the spent fuel pool were on this work platform (or some were, not sure which).

 

[jim hardy]

I believe they have built a platform all around unit 3 building at the refueling floor height; the strips are probably draped covers to protect the scaffolding. The cranes working to clear stuff from the spent fuel pool were on this work platform (or some were, not sure which).

Amazing how clear the top floor is now... soon we may see top of containment vessel, hopefully ?

About the rat:



https://www.youtube.com/watch?v=2LZ0q78OWZE

that's why it's enclosed in metal.

( my first ever embed ! Thanks mentors, for that FAQ page.)

 

[LabratSR]

TEPCO to drill hole in floor of Unit 2 in order to access torus room.

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130322_02-e.pdf

 

[rmattila]

It appears the NRC has rejected the requirement for filtered vents in US Mark I/II plants: http://berkeley-nj.patch.com/articles/nrc-to-enhance-post-fukushima-vent-requirements-d1361586

 

[tsutsuji]

TEPCO to drill hole in floor of Unit 2 in order to access torus room.

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130322_02-e.pdf

For reference, here is the report on the 27/28 January attempt that failed because of obstacles : http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130128_03-e.pdf

 

[LabratSR]

It appears the NRC has rejected the requirement for filtered vents in US Mark I/II plants: http://berkeley-nj.patch.com/articles/nrc-to-enhance-post-fukushima-vent-requirements-d1361586

http://pbadupws.nrc.gov/docs/ML1307/ML13078A415.pdf

 

[nikkkom]

The Commission directed the staff to consider both the use of a filter to be placed on the vent, as well as a more performance-based approach using existing systems to achieve a similar reduction in radioactive release during an accident, a news release from the NRC said.

“With respect to the latter, it involves, among other things, plant operators using containment sprays and flooding to deal with the aftermath of a severe accident,” Sheehan said. “Also, Mark 1 Boiling Water Reactors can use the torus to help filter radioactive gases.”

This sounds bad. Nuclear people are still not getting it.

What containment sprays in Fukushima-like situation, what flooding, pray tell?
You should be preapared to handle a situation when THERE IS NO POWER AT ALL. You won't be able to activate those sprays!

Essentially, the NRC has rejected its Japan lessons learned project directorate and senior management who recommended that the Mark I and Mark II containments be equipped with a severe accident capable vent and a high capacity radiation filter, he said. Although the venting systems will be improved, the filter aspect has been rejected.

Exactly how I see it.

 

[NUCENG]

This sounds bad. Nuclear people are still not getting it.

What containment sprays in Fukushima-like situation, what flooding, pray tell?
You should be preapared to handle a situation when THERE IS NO POWER AT ALL. You won't be able to activate those sprays!



Exactly how I see it.

Passive filtration is the only enhancement that is not going forward. NRC Commissioners concluded the staff has not justified the safety improvement without going through the rulemaking process. The Order calling for improvements in system operability at accident pressures, temperature, and radiation levels of severe accidents, and to make the system operat6ion power independent, is proceeding.



There are additional improvements in power reliability and backup for actiive filtration (i.e. containment spray).

 

[tsutsuji]

Here is the last monthly mid & long term report from Tepco, dated 7 March 2013 (246 pages, 11.9MB, Japanese) :

http://www.tepco.co.jp/nu/fukushima-np/roadmap/images/d130307_01-j.pdf

I indicate the page numbers and translate the titles of each presentation. For clarity's sake, I kept the main titles "2.1" through "3.7" that used to be mentioned on the Ministry of Economy, Trade and Industry's mid and long term documents. 2-1: Plant status

16/246 - 19/246 : Plant parameters

20/246 - 21/246 : Accumulated water storage status

3-1 Cooling by closed loop water injection

22/246 - 23/246 : Closed loop water injection cooling schedule

24/246 - 27/246 : Schedule revision of installation work of a nuclear reactor water injection system using the condensate storage tank as source

28/246 - 36/246 : Reliability improvement work on units 1,2,3 reactor injection points (feedwater systems)

37/246 - 46/246 : Results of TIP guide tube soundness verifications for the purpose of unit 2 reactor internal inspection and thermometer installation

47/246 - 57/246 : Execution of monitoring instruments installation and internal investigation into unit 2 PCV

A result report dated 19 March 2013 is available in English : http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130319_03-e.pdf indicating some problems : "Since the CRD replacement rail could not be found, the investigation of the rail and the area near the pedestal could not be performed. The camera was able to reach the upper part of the grating on the first floor". Also the guide pipe "got stuck".

3-2 Treatment of accumulated water

58/246 : Accumulated water treatment schedule

59/246 - 74/246 : Groundwater bypass progress status and preparations for starting

75/246 - 145/246 : Status of the safety assessment studies needed for the start of the multinuclide removal facility

3-3 Countermeasures to reduce environmental radiations

146/246 - 148/246 : Results of evaluation of additional releases from reactor buildings

3-4 Improvement of working conditions

149/246 - 150/246 : Improvement of working conditions schedule

3-5 Countermeasures for spent fuels pools

151/246 - 152/246 : Spent fuel pool countermeasure schedule

153/246 : working area layout map of units 3 and 4 top part debris removal work and covering work for the purpose of fuel removal

154/246 : Debris removal work, reactor building top part, unit 3

155/246 : Debris removal work, reactor building top part, unit 4

156/246 - 159/246 : Unit 2 reactor building operating floor gamma camera inspection results (prompt report)

An English language result report, dated 22 February 2013, is available :
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130222_04-e.pdf

160/246 : Investigation Results of Unit 3 Spent Fuel Pool using Underwater Camera (Performed on February 14, 15, 16 and 18)

An English version, dated 21 february 2013, is available here : http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130221_01-e.pdf

161/246 - 166/246 : Revision of the schedule of unit 3 reactor building top part debris removal work

167/246 - 174/246 : Completion of the removal of steel truss debris above Unit 3 SFP

A few pages have been translated into English at http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130206_01-e.pdf (dated 6 February 2013)

3-6 Preparations for fuel debris removal

175/246 - 176/246 : fuel debris removal preparation work schedule

177/246 - 193/246 : Analysis results of reactor building contamination samples, as part of the "development of indoors remote decontamination technology" project

194/246 - 207/246 : Reopening of inspection into unit 2 vent pipe lower part surroundings

Related English language documents :
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130315_01-e.pdf (March 15)
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130314_01-e.pdf (March 14)
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130313_03-e.pdf (March 13)
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130306_03-e.pdf (March 6)
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130305_01-e.pdf (March 5)

208/246 - 218/246 : Removal of obstacles such as the debris on units 1 and 3 first floors

219/246 - 228/246 : Unit 1 torus room inspection results

Related English language document : http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130222_05-e.pdf (22 February 2013)

3-7 Treatment and disposal of radioactive waste

229/246 : treatment and disposal of radioactive waste (schedule)

230/246 : Debris, cut down trees management status (as of 31 January 2013)

231/246 - 234/246 : Debris, cut down trees radiation reduction countermeasures progress status

235/246 - 246/246 : Radiation analysis of sampled debris and cut down trees (interim report) (by JAEA)

 

[a.ua.]

For dose rate in the building space
http://www.tepco.co.jp/nu/fukushima-np/f1/images/f1-sv3-20130322-j.pdf

 

[rmattila]

The NRC voting record on the venting issues: http://www.nrc.gov/reading-rm/doc-collections/commission/cvr/2012/2012-0157vtr.pdf

 

[tsutsuji]

Going one month backwards, here is the monthly mid & long term report dated 31 January 2013 (151 pages, 7.3 MB, Japanese) :

http://www.tepco.co.jp/nu/fukushima-np/roadmap/images/t130131_01-j.pdf

2-1: Plant status

10/151 - 13/151 : Plant parameters

14/151 - 15/151 : Accumulated water storage status

3-1 Cooling by closed loop water injection

16/151 - 17/151 : Schedule

18/151 - 29/151 : Results of unit 1 PCV internal survey (includes PCV accumulated water analysis and observations on the taken photographs)

3-2 Treatment of accumulated water

30/151 : Schedule

31/151 - 86/151 : Safety assessment as needed for the start of the multinuclide facility

87/151 - 91/151 : Groundwater bypass demonstration test results and progress status

3-3 Countermeasures to reduce environmental radiations

92/151 - 93/151 : Schedule

94/151 - 107/151 : Status of radioactive substance concentrations inside harbor

108/151 - 110/151 : Results of evaluation of additional releases from reactor buildings

3-4 Improvement of working conditions

111/151 - 112/151 : schedule

3-5 Countermeasures for spent fuels pools

113/151 - 114/151 : schedule

115/151 : Layout map of working areas of units 3 and 4 top part debris removal work and covering work for the purpose of fuel removal

116/151 : Debris removal work, reactor building top part, unit 3

117/151 : Debris removal work, reactor building top part, unit 4

118/151 - 121/151 : Dry storage cask soundness verification

121/151 - 125/151 : Visual inspection of the fuel and inspection of the racks in the common pool

3-6 Preparations for fuel debris removal

126/151 - 127/151 : Schedule

128/151 : 139/151 : Units 1 and 2 torus room surveys

140/151 - 145/151 : Four-legged robot technology working group study status (remote control task force)

3-7 Treatment and disposal of radioactive waste

146/151 : Schedule

147/151 : Debris, cut down trees management status (as of 27 December 2012)

148/151 - 151/151 : Debris, cut down trees radiation reduction countermeasures progress status

 

[tsutsuji]

Going two months backwards, here is the mid & long term report from Tepco dated 25 December 2012 (the 13th Tepco-Government mid & long term meeting), revised on 31 January 2013.

http://www.tepco.co.jp/nu/fukushima-np/roadmap/images/m121225_04-j.pdf (6 pages, 1.2 MB, Japanese)

2-1: Plant status

1/6 - 4/6 : Plant parameters

5/6 - 6/6 : Accumulated water storage status

http://www.tepco.co.jp/nu/fukushima-np/roadmap/images/m121225_05-j.pdf (115 pages, 3.6 MB, Japanese)

3-1 Cooling by closed loop water injection

1/115 - 2/115 : Schedule

3/115 - 12/115 : Status of studies toward the practical use of unit 2 TIP guide tubes

13/115 - 20/115 : Execution of nitrogen injection into unit 2 suppression chamber

21/115 - 26/115 : Installation of the new (C) nitrogen gas separator

3-2 Treatment of accumulated water

27/115 : Schedule

28/115 - 30/115 : Groundwater bypass demonstration test

31/115 - 50/115 : Multinuclide facility : status of high integrity container soundness evaluation against falling

3-3 Countermeasures to reduce environmental radiations

51/115 : Schedule

52/115 - 54/115 : Radiation reduction at plant premises boundary (status report as of December)

55/115 - 56/115 : Closure of unit 2 reactor building blowout panel aperture

57/115 - 59/115 : Results of evaluation of additional releases from reactor buildings

60/115 - 62/115 : Reduction of radioactive substance concentrations in harbor seawater : survey results and future response

3-4 Improvement of working conditions

63/115 - 64/115 : schedule

3-5 Countermeasures for spent fuels pools

65/115 - 66/115 : schedule

67/115 : Layout map of working areas of units 3 and 4 top part debris removal work and covering work for the purpose of fuel removal

68/115 : Debris removal work, reactor building top part, unit 3

69/115 : Debris removal work, reactor building top part, unit 4

70/115 - 75/115 : Unit 3 reactor top part debris removal work : removal of submerged steel beam debris

76/115 - 83/115 : Gamma camera survey on unit 2 operating floor

84/115 - 87/115 : Visual inspection of the spent fuel and inspection of the racks in the common pool

3-6 Preparations for fuel debris removal

88/115 - 89/115 : Schedule

90/115 - 94/115 : Demonstration of 3D CAD using laser scan technology

95/115 - 102/115 : Demonstration tests at Fukushima Daini NPP as part of Research & Development project "Development of indoors remote decontamination technology"

103/115 - 110/115 : Unit 2 vent pipe lower part surroundings inspection progress status and future plans

3-7 Treatment and disposal of radioactive waste

111/115 : Schedule

112/115 : Debris, cut down trees management status (as of 30 November 2012)

113/115 - 115/115 : Reduction countermeasures toward the achievement of a yearly 1 mSv radiation at Northern premise boundary

 

[tsutsuji]

http://www.tepco.co.jp/nu/fukushima-np/handouts/2013/images/handouts_130325_04-j.pdf a more detailed report on the short circuit caused by a rat.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130325/index.html Tepco confirmed that the blackout was caused by a rat. Tepco said : "Even among the other switchboards that are located indoors, some have cables than run to the outside, and we are urgently studying countermeasures so that small animals do not come in through interstices".

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130327/1430_hokoku.html An interim report was released at the spring meeting of the Atomic Energy Society of Japan, by the 40 member Fukushima Daiichi investigation committee that was set up by AESJ last August, with the purpose of examining the accident from a specialist's point of view. The interim report asserts such things as "if the safety preparations had been sufficient, high amounts of radioactive substances would not have been released even if an accident occurs, and causing social trouble could have been avoided". A questionnaire survey among AESJ members and former members collected many repentances such as "excessive pride and self confidence in safety" and "as a member of the nuclear village, there was a [too] reserved attitude against the power companies". However, the interim report contents itself with summarizing the facts already brought to light by the government and diet investigations, and provides almost no analysis or scientific investigation of its own. Committee president Satoru Tanaka said the technical problems will be addressed next. The final report is expected by December.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130327/index.html The NRA is setting up a Fukushima Daiichi accident analysis study group. The group will meet about once per month and its achievements will be publicly released.

 

[a.ua.]

http://www.tepco.co.jp/nu/fukushima-np/f1/genkyo/fp_reactor/fp_gdata/__icsFiles/afieldfile/2013/03/13/bassaiboku-j.pdf

A large amount of cobalt 60 at fuel rods from 4 pools.
The result of the criticality and neutron radiation flux.?

 

[jim hardy]

A large amount of cobalt 60 at fuel rods from 4 pools.

do you know where was that measured?

Reactor steel is selected for low cobalt content but it's not zero.
Might be coming from the steam dryers or shroud , if they're in the pool.

http://www.evs.anl.gov/pub/doc/Cobalt.pdf

Where Does It Come From? Cobalt is naturally present as the isotope 59 in various ores and to a
lesser extent in soil. Cobalt-60 is produced by neutron activation of components in nuclear reactors;

Co60 is a comparatively penetrating gamma ray that'll go considerable distance.

 

[NUCENG]

http://www.tepco.co.jp/nu/fukushima-np/f1/genkyo/fp_reactor/fp_gdata/__icsFiles/afieldfile/2013/03/13/bassaiboku-j.pdf

A large amount of cobalt 60 at fuel rods from 4 pools.
The result of the criticality and neutron radiation flux.?

I may be mistranslating, so please help me out. But this appears to be data about debris and tree clearance samples. The reports for Co-60 Bq/gm activity are four orders of magnitude lower than Cs-137. Agreed, Co-60 is a very energetic radiation source, but its activity is hardly a "large amount" wwhen compared to thre total source term in the samples.

The two exceptions samples 4U-N01 and N03 are described as Unit 4 "rubble?". I don't see any tie to 4 spent fuel pools. a.ua. can you explain?

 

[a.ua.]

4U‐N01 Rubbed with a cloth rod, it is dirt that remains on the rag.

Hmm, maybe the neutron flux was coming from the spent fuel, which got taken out at the planned preventative maintenance.?

But in Chazhma Bay also had a lot of cobalt 60.



jim hardy thank you!

 

[NUCENG]

4U‐N01 Rubbed with a cloth rod, it is dirt that remains on the rag.

Hmm, maybe the neutron flux was coming from the spent fuel, which got taken out at the planned preventative maintenance.?

But in Chazhma Bay also had a lot of cobalt 60.
jim hardy thank you!

Sorry, I didn't understand that. Jim is right that activation of Cobalt is the masin source of Co-60, and that requires a neutron flux consistent with your last post, but if I was reading Japanese correctly the sample was near Unit 4. Your initial post suggested there was a lot of Co-60 from the four spent fuel pools. Were you suggesting criticality in Unit 4 SFP to explain the Co-60 in the samples or a wider problem at all the reactors. I'm trying to clarify only.Woops just saw the fine print about the Russian submarine accident. I'll take another look. Co-60 has a very low yield as a fission product in light water reactors with low enrichment. It is possible that changes in a criticality accident or it may be due to higher Co-59 inventory in old Soviet fuel design. More to follow.

 

[NUCENG]

Co-60

It is clear that the fission product yield of Co-60 is near zero and that wouldn't be significantly different in a criticality accident even assuming fast fission. Old Soviet Submarine fuel designs may have used stainless steel cladding which would explain increased Co-60.
So it looks to me like the release of Co-60 is not likely to be fuel debris. Activation of steel or other materials containing Cobalt is the only likely source of Co-60 at Fukushima. If the samples (cloth swipes) were taken from the fuel pool or some rubble outside of Unit 4 it means that we can't really tell whether that indicates a criticality event. The dryers and separators and the old core shroud at unit 4 would be possible sources for debris. If these were stored in the equipment pool under water, I'm unsure how a hydrogen gas explosion in unit 4 would have blown parts of these items outside the building. They would haave been at opposite ends of the refuel floor. If these items were on the refuel floor it would be more likely.

 

[a.ua.]

NUCENG

If the samples (cloth swipes) were taken from the fuel pool

Yes they were taken from the fuel pool.

 

[SteveElbows]

Hello, I am back after taking my eyes off the situation for some months. Have we discussed any reports or data relating to the following translation of a press article? It is concerning the time that water injection into reactor 3 may have stopped, with the possibility that it stopped 6 hours earlier than TEPCO had previously assumed.

http://ex-skf.blogspot.co.uk/2013/03/fukushima-i-nuke-plant-reactor-3-those.html

The press report is only days old, but it sounds like the data it is based on is from last year, any ideas about this data?

People may remember that I was always rather unimpressed with the timing & water assumptions TEPCO used when attempting to estimate core damage based on factors such as decay heat and water levels in the reactor. So I am pleased to hear that they are apparently going to redo their analysis in response to this data. I hope that this time they also do not simply use the most optimistic of assumptions in terms of when fire-engine pumped water injection started, and do not assume that this was uninterrupted and sufficient once it began. Especially in light of the other stuff discussed earlier about the possibility that a lot of that water ended up in the condenser.

 

[SteveElbows]

The other thing I don't think I see mentioned here from recent months is that on February 1st TEPCO published a huge number of photographs from the early days of the disaster. Some of them are the same or very similar to ones they released previously, others are from different angles or show thing we didnt see before.

I haven't had time to look closely at every single one of them, but I didnt spot anything too interesting upon initial inspection.

There were however a number of additional images similar to the one we previously found that shows clouds of material escaping from reactor 2 on March 15th. (see 3rd zip file for these). A few similar shots taken a few days later in zip number 8.

Zip 16 appears to contain many shots of the attempted water spraying at night of reactor 3, a video of which had long ago caused some confusion here about the target due to the side of the building they were attempting it from. Zip 11 contains shots from a similar mission conducted in daytime a day or two earlier, the last shot of which is one of the highest resolution/sharpest photos of reactor 3 building damage that I've seen.

Zip 20 contains some more shots of the March 21st reactor 3 smoke event.

There may be others that interest people, these were just the ones that immediately caught my eye. But I expect they would have been more interesting if we had been able to see them closer to the time they were taken, rather than all this time later.

http://photo.tepco.co.jp/en/date/2013/201302-e/130201-01e.html

 

[jim hardy]

If they announced finding those data last fall I must've missed it.
I followed jstolfi's plots.

From your exskf aeticle:

However, the data on water levels recorded by the operator at that time surfaced in fall last year,

so it had been misplaced, overlooked, or dismissed ?
Not a criticism of TEPCO, just that's how things go when you're investigating such messes. They're puzzles, one gets pieces of information that don't fit and it takes a long time to make sense of it all. Been there, done that. Glad to hear they're still working on it.

Depending on the result of the new analysis, it is possible that the conditions to estimate the dispersion of radioactive materials will change.]

Well, yeah..
If my memory is any good,
that's around the time they measured a few neutrons at the gate.
Direction of breeze was variable.
Might have vented some unexpected soot.

Ever watch Detective Columbo piece together his mysteries?


old jim

 

[tsutsuji]

The 4U-N01 and 4U-N02 samples are from the rubble found in the fresh fuel assemblies removed from SFP 4 last summer : http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120828_01-e.pdf

4U-N01 is from the rubble collected by filtering the water in a cloth after washing the fuel ;

4U-N02 is from the rubble found between the rods after removing the channel box(es).

 

[LabratSR]

TEPCO releases document that answers questions about the use of the harbor at Fukushima.

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130327_01-e.pdf

 

[tsutsuji]

the monthly mid & long term report dated 31 January 2013 (151 pages, 7.3 MB, Japanese) :

http://www.tepco.co.jp/nu/fukushima-np/roadmap/images/t130131_01-j.pdf

3-1 Cooling by closed loop water injection

18/151 - 29/151 : Results of unit 1 PCV internal survey (includes PCV accumulated water analysis and observations on the taken photographs)

Translation :

18/151

19/151

20/151

 

[tsutsuji]

Translation :

21/151

22/151

23/151

 

[tsutsuji]

Translation :

24/151

25/151

26/151

 

[tsutsuji]

Translation :

27/151

28/151

29/151

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130330/index.html The multinuclide removal facility's test run using real highly contaminated water will begin on 30 March. The facility can remove 62 kinds of radioactive substances. The test run had been planned for last September, but it incurred a 6 month delay caused by a number of problems such as finding that the containers were not strong enough. The NRA approved Tepco's countermeasures last week. At first only the first one of the 3 lines shall be tested. The test is expected to take 4 months. As there are two other lines to test next, there is no prospect that normal operation can start within 2013 as originally planned. Including the groundwater that seeps in, 400 tons of contaminated water are produced everyday at Fukushima Daiichi.

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130329_01-e.pdf Overview of the Multi-nuclide Removal Equipment (ALPS) at Fukushima Daiichi Nuclear Power Station

 

[turi]

Thanks tsutuji. Nice to have some pictures from reactor one's PCV.
Just shows me again, that I always underestimate the density of lead... 4.2 t of lead just from the 16 penetration end and collar shields. Wow. But "only" 0.37 m³.

 

[LabratSR]

RE: Filtered Vents. I came across this post by Sherrell Greene.

http://www.sustainableenergytoday.blogspot.com/2013/03/post-79-to-vent-or-not-to-vent-that-is.html


Sherrell Greene was a member of the BWR Severe Accident Analysis group at Oak Ridge. A list of his publications can be found here.

http://sustainableenergytoday.blogspot.com/2011/04/post-38-my-professional-publications.html

 

[tsutsuji]

monthly mid & long term report from Tepco, dated 7 March 2013 (246 pages, 11.9MB, Japanese) :

http://www.tepco.co.jp/nu/fukushima-np/roadmap/images/d130307_01-j.pdf

3-1 Cooling by closed loop water injection

37/246 - 46/246 : Results of TIP guide tube soundness verifications for the purpose of unit 2 reactor internal inspection and thermometer installation

A full English translation of that part was made available at : http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130301_03-e.pdf

 

[nikkkom]

Passive filtration is the only enhancement that is not going forward.

You mean, the missing safety feature which could possibly have kept Fukushima from becoming a *major* radiological release is not going to be installed on the US plants?

NRC Commissioners concluded the staff has not justified the safety improvement without going through the rulemaking process.

What does it mean in plain English?

There are additional improvements in power reliability and backup for active filtration (i.e. containment spray).

"Total blackout is impossible, no need to prepare for it"? I think I heard this sort of thing before. March 2011 comes to mind.

 

[tsutsuji]

http://www.nsr.go.jp/disclosure/meeting_operator/NEP/data/20130226_05giji.pdf [26 February 2013 Tepco-NRA meeting] : During the lecture organised on 13 February 2013 by Democratic Party representative Shoichi Kondo (where Tepco was also a participant), former representative Hiroshi Kawauchi requested a study toward the acquisition of Fukushima Daiichi unit 1 process computer system logs. In response, Tepco provides the following explanations :

- System log data acquisition work will start in March 2013, and analysing the logs could take up to one or two months, so that a result can be expected no later than in May or June.
- A business contract between Tepco and the maker Toshiba is necessary for the unit 1 process computer system log acquisition work. The contract is presently being prepared.
- According to Toshiba, apart from the process computer, there is another personal computer dedicated to system log recording and management, and it is possible to acquire the system logs by the restoration of the aforementioned personal computer.
- The onsite radiation is about 15 microsievert/hour

See also http://www.tepco.co.jp/en/nu/fukushima-np/plant-data/f1_1_Setsumei.pdf page 5/13 (published in May 2011) saying that contrary to unit 2 and unit 5, unit 1's "data of process computer (operation data)" are "difficult to obtain".

 

[Hiddencamper]

You mean, the missing safety feature which could possibly have kept Fukushima from becoming a *major* radiological release is not going to be installed on the US plants?



What does it mean in plain English?



"Total blackout is impossible, no need to prepare for it"? I think I heard this sort of thing before. March 2011 comes to mind.

With regards to passive filtration, they are only viable if there is no containment bypass leakage. If the containment is damaged it wouldn't have mattered. As we've seen at Fukushima, the majority of radiological release "appears" to be from unit 2, and unit 2 is the one which may have had a total breach or loss of containment integrity.

Considering this points, the fact that they were unable to break the rupture disk at unit 2, that there was containment leakage and potential pool bypass, a filter would have provided no benefit.

I'm not saying filters are a bad thing in general, but you need to fully understand sequences which a filter may or may not have been a benefit. If Fukushima had portable pumps at all units staged and proper severe accident procedures, they would have likely been able to achieve similar decontamination factors without filters.

Also the US has NOT ruled out filters (i don't know why all these people keep saying that, its completely not true). The NRC commission voted to use the RULEMAKING process to decide vents and decontamination post accident, and also to develop a strong technical basis.