Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[joewein]

At unit 2 the problem was not running out of water. The problem was the RCIC stopping for some not well identified reason :

The RCIC still needs battery power for operating valves and this could have run out. Another possibility is that, since the RCIC uses the suppression chamber pool as its heat sink, which is also heated by venting from the RPV, the suppression chamber pool became too hot to condense steam, which would stop the RCIC turbine.

Also, we should remember that not all units had an RCIC: Unit 1 only had an isolation condenser and perhaps not by coincidence, is assumed to have suffered meltdown only about 5 hours after station blackout, 2-3 days before the other units.

Great suggestions in http://sustainableenergytoday.blogspot.com/2011/07/post-47-tv-asahi-interview-on-bwr.html" :

Assured containment cooling: A secure means of cooling the primary containment pressure suppression pool and drywell atmosphere under SBO conditions. A number of options are possible, but the use of diesel-driven RHR pumps and drywell coolers powered by backup power systems are options.

Had there been a way of using temporary sea-water pumps to cool the suppression chamber or containment, the RCIC could have operated longer and containment venting would have been much less urgent, as steam could have continually been condensed inside.

Also, if the designers of the RCIC had run a generator off its steam turbine and not just a water pump, the dependence on batteries for operating RCIC valves would not have been its Achilles heel.

 

[tsutsuji]

Concerning Fukushima Daiichi unit 3, Tepco says on the one hand "The inability to use the residual heat removal system seawater pumps meant the loss of residual heat removal system (RHR) functions, resulting in a failure to shift the decay heat in the PCV to the sea, the final heat sink", then a few lines below : "The reason why the RCIC stopped at 11:36 on March 12 is unknown at this time, but the storage batteries for valve manipulation might have become exhausted as more than 20 hours had passed since the RCIC started operation" (page IV-73 http://www.iaea.org/newscenter/focus/fukushima/japan-report/chapter-4.pdf ) so that it seems that the loss of the seawater pumps was not the immediate cause of the accident.

Great suggestions in http://sustainableenergytoday.blogspot.com/2011/07/post-47-tv-asahi-interview-on-bwr.html" ad there been a way of using temporary sea-water pumps to cool the suppression chamber or containment, the RCIC could have operated longer and containment venting would have been much less urgent, as steam could have continually been condensed inside.

My understanding is that the RCIC turbine basically needs a difference of pressure. Did we reach a point when the pressure in the suppression chamber became so high that the steam flow in the RCIC turbine was not enough to move the turbine ?

If the safety-related cooling pumps were destroyed by the tsunami, then the RHR isn't going to work, and once the water supply to RCIC is used up, then heat removal won't be possible.

Basically this is the problem they had at Fukushima Daini unit 1 as indicated on the right part of the table page 62 of http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf : they had lost their RHR sea water pump, but nearly everything else was all right. And they managed to keep the reactor stable enough until they could repair that pump by changing the motor (see page 54 http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf and "The motors of the RHR system cooling water pump (D) and emergency component cooling water pump (B) necessary for the RHR system (B) operation were replaced with new ones in order to maintain a means of heat removal by the RHR. (...) As a result, the operation of the RHR system (B) started to cool the suppression chamber at 01:24 on March 14" : page IV-115 http://www.iaea.org/newscenter/focus/fukushima/japan-report/chapter-4.pdf ) .

 

[joewein]

My understanding is that the RCIC turbine basically needs a difference of pressure. Did we reach a point when the pressure in the suppression chamber became so high that the steam flow in the RCIC turbine was not enough to move the turbine ?

According to the http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/data/pres-un2-t.txt" , the unit 2 S/C was under about 6 bar of pressure on March 13 (I assume the unit is KPa):

2011-03-13 | 10:35:00 |  10
2011-03-13 | 13:00:00 | 590
2011-03-13 | 14:10:00 | 600

Same data for http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/data/pres-un3-t.txt" :

2011-03-13 | 07:05:00 |  430
2011-03-13 | 07:10:00 |  430
2011-03-13 | 07:15:00 |  435
(...)
2011-03-13 | 08:35:00 |  445
2011-03-13 | 08:55:00 |  455
2011-03-13 | 09:10:00 |  590
2011-03-13 | 09:15:00 |  590

Unfortunately there appears to be no published temperature data for the torus in the first couple of days, but if the published pressure was due to steam, the suppression pool water must have been pretty hot by then. http://www.efunda.com/materials/water/steamtable_sat.cfm" at 146 deg C at 430 KPa and at 159 deg C at 600 KPa. It would not have been very good at condensing steam from the RCIC at that temperature, or put another way, the RCIC turbine would have had a lot of back pressure even if input pressure was over 6 MPa.

At Fukushima-II, which has BWR5 reactors (same as unit 6 at F-I) the suppression pools of units 1, 2 and 4 topped 100 deg C on the morning after the quake (reported to NISA: unit 1 @ 05:22 on 2011-03-12; unit 2 @ 05:32; unit 4 @ 06:07) after the RHR lost its sea water supply. Unit 3 was OK because its sea water pumps were undamaged. They only recovered after the sea water pumps were repaired and the RHR restarted. Admittedly, the F-II data doesn't necessarily tell us much about timing, as they used a different containment (mark 2 vs. mark 1) as well as having a higher power rating (1100 MWe vs. 784 MWe).

 

[tsutsuji]

It would not have been very good at condensing steam from the RCIC at that temperature, or put another way, the RCIC turbine would have had a lot of back pressure even if input pressure was over 6 MPa.

If the suppression pool pressure rises to such heights that the steam flow won't move the RCIC turbine, couldn't you, as a last resort measure, vent the suppression pool into the atmosphere ? Steam engines don't need a cooling system provided you are allowed to release the steam into the atmosphere.

It sounds like both units 5 and 6 and Fukushima Daini were located high enough that the turbine halls and reactor buildings doors weren't reached by the flood and in Daini the sea water pumps were better protected by being enclosed in a small concrete building.

Actually units 5 and 6 did suffer flooding as shown by http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110516e22.pdf (unit 5 exciters submerged, or unit 6 switchboards submerged) (thanks MJracer for the link). However unit 6's diesel generator 6B, being located on the ground floor in a separate building, and being air-cooled, survived. That building was surrounded by a 0~1 m high wave above ground, as shown on http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf page 36. Either the wave was lower than the sensitive parts of the 6B diesel generator, or the door and walls were tight enough and no water entered the building.

More detail can be seen in the following diagrams. First is a http://2.bp.blogspot.com/-UtgJZNeAdlU/Ta3z9i97ryI/AAAAAAAAEfs/HehSEK2k60I/s1600/R1-R4.PNG" with schematic drawings of the estimated sea water piping circuits.

(...)
At the bottom left there is a legend beginning with "Sovrapposizione ..." which I translate as superposition of the buried plan view of Reactor 3 in relation to the turbine building at various heights (OP-2060mm (the torus was below sea-level?), OP+1900mm (the diesel generators) and OP+300mm (the switchboards)). So the switchboards were apparently 1.6 meters or more than 5 ft below the generators.

Unit 3 can be seen in more detail http://3.bp.blogspot.com/-JaxFid8Qo...Ako/t5TVRl5sb-4/s1600/R3++completa+small.jpg".

The generators are at the top above the turbines (look for the word "diesel") and the switchboards are at the bottom in light green bracketed in blue with a note that says that Unit 2 probably did not have them or did not have them at that location. It is unclear if these switchboards were common to both units.

"the torus was below sea-level?" : Yes, this is confirmed on the figure page 5 of http://www.kantei.go.jp/foreign/kan/topics/201106/pdf/attach_04_3.pdf. It is aslo known that unit 1's reactor building reaches at least 1.23 m below sea level as "The measuring point in the basement of R/B of Unit 1 [is] O.P.-1,230mm" : http://www.nisa.meti.go.jp/english/press/2011/06/en20110616-1-5.pdf

"OP+300mm (the switchboards)" and "apparently 1.6 meters" : Actually the height indicated for that level on http://3.bp.blogspot.com/-JaxFid8Qo...AAko/t5TVRl5sb-4/s1600/R3++completa+small.jpg is OP -300 mm (minus 300 milimeters). So the switchboards were apparently 1.9+0.3=2.2 meters lower than the Diesel Generators. The OP+1900 mm height of diesel generators is approximately confirmed by the figure page 5 of http://www.kantei.go.jp/foreign/kan/topics/201106/pdf/attach_04_3.pdf although no dimension is explicitly written.

In hindsight, the seaside pumps may have been hardened at Dai-ichi like they were at Dai-ni by protecting them with a building, but there was no cure for the switchboards other than relocating them completely once the reactors were built. Obviously, the diesel generators could have been relocated as well.

The seawater pump buildings at Daini were not so helpful. It turns out that 3 out of 4 seawater pumps broke down. I would be happy to know the exact reason why the remaining one (the one belonging to unit 3) survived, though.

I think the background of http://www.tepco.co.jp/en/news/110311/images/110717_1.jpg (or http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110717_01-e.pdf ) is, from left to right : the Futaba and Yonomori power lines, unit 5 reactor building and unit 5 turbine building.[/URL]

This can also be confirmed by the matching of color patterns on unit 5 reactor building as pictured on http://www.houseoffoust.com/fukushima/tepco_pics/fukudaiichi5_6.jpg available from http://www.houseoffoust.com/fukushima/phototour.html (see also http://www.houseoffoust.com/fukushima/tepco_pics/fuku_switchingstation2.jpg showing the other side of the 500 kV unit 5 and 6 switching station)

Thanks for all these informative links. I was not aware there was a fallen crane?

We talked about it in May : http://www.netimago.com/image_202944.html

At long last, I found a picture showing the crane (near unit 6 water intake) before the tsunami : http://www.houseoffoust.com/fukushima/tepco_pics/r6_waterpump4.jpg (incidentally, this is also a good comparison reference for the breakwater damages)

 

[tsutsuji]

http://www.fnn-news.com/news/headlines/articles/CONN00203983.html the installation of a bypass hose at the exit of the Areva system requires working in a 50 mSv/hour environment. At 11:00 AM on 24 July, the injection flow into unit 1 reactor was found to be down from 3.5 to 3.3 m³/hour. Tepco raised it to 3.8 m³/hour.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110724_01-e.pdf (page 2) T-hawk helicopter doing its job taking dust samples on reactor buildings on 22, 23, 24 July.

 

[NUCENG]

If the suppression pool pressure rises to such heights that the steam flow won't move the RCIC turbine, couldn't you, as a last resort measure, vent the suppression pool into the atmosphere ? Steam engines don't need a cooling system provided you are allowed to release the steam into the atmosphere.

RCIC and HPCI are designed to operate over a significant pressure range. However at some point the design basis for ECCS system transfers to low pressure injection systems (RHR and Core Spray. Also,fire trucks and other portable pumps would have a hard time pumping into a 6 MPa RPV). HPCI and RCIC turbines use a reversing water wheel design to extract maximum energy from the steam they use. Back pressure is considered in the design, but would not have been a problem for the turbines at the pressures indicated in the torus at Unit 2 or 3. The bigger problem is that once the suppression pool temperature exceeds the saturation point the result of continuing HPCI or RCIC operation is to add uncondensed high pressure steam into the suppression chamber threatening the containment integrity. At this point operators would also lose the ability to control RPV pressures with SRVs without damaging the containment. The lack of Suppression Pool and Drywell temperature data makes it difficult to determine if this happened at either Units 2 or 3.

HPCI and RCIC systems also have a low pressure steam supply isolation trip about 500 to 600 kPa (at least in US plants) to recognize that the Low Pressure systems should be running and because pressures are low enough that HPCI and RCIC turbine operation is at their limits.

At Fukushima the low pressure ECCS systems were not available due to loss of AC power so operators probably delayed depressurizing the RPV as long as they could.

Using The plots and data generated by Mr. Stolfi, (Thanks) Unit 2 RC pressure dropped to near Torus pressure after noon on 3/14 coinciding with the marked timeline labeled “Meltdown.” However the RPV level dropped below instrument zero earlier that morning so the loss of makeup occurred sometime earlier when level dropped. The length of time the operators maintained level in Unit 2 far exceeded either a 4 hour or 8 hour battery depletion time. In other words they did something right to extend the time to core damage.

Using the same plots for Unit 3, things were not so rosy. RPV level was below zero when Stolfi’s level plots start. Again Pressure for the RCIC or HPCI steam supply dropped coincident with the time marked “Meltdown” . The operator logs at Unit 3 and early TEPCO news releaeses reported problems with operation of HPCI (stopped) at 0242 on 3/13, but did not describe the problem in any detail. An hour and a half later the level was estimated to be below TAF.

 

[jim hardy]

"""If the suppression pool pressure rises to such heights that the steam flow won't move the RCIC turbine, couldn't you, as a last resort measure, vent the suppression pool into the atmosphere ? Steam engines don't need a cooling system provided you are allowed to release the steam into the atmosphere. """


I think i recall from the NRC report on extended blackout, using Brown's Ferry's specific plant design as a 'typical' example, that the RCIC steam turbine has a temperature switch to shut it down should ambient temperature reach 200F. Reason is that high ambient temperature infers a steam leak. I would guess that happened with no seawater to provide basic cooling to the plant.
http://www.ornl.gov/info/reports/1981/3445600211884.pdf
see page 63 of report, pdf page 75.

Also, the RCIC equipment is not located in a closely confined space, and
some natural convection within the reactor building will certainly occur.
Nevertheless, it is conceivable that the local temperature in the vicinity
of the steam leak detection sensors could reach 93.3°C (200°F) during RCIC
system operation after the average space temperature has increased to over
60°C (140CF). If this occurs, the resulting RCIC system isolation signal
can be overriden in the auxiliary instrumentation room and the steam sup
ply valves reopened and the turbine trip reset.

which presumes you can get into those rooms.

I never worked around a BWR - probably Nuceng knows way better than me.

old jim

 

[tsutsuji]

At around 11:57 am on July 24, water desalinations were automatically shut-downed after annunciator alarmed. From 7:19 pm on the same day, the water desalinations were restarted after switching to the spare equipment. The water injection into Reactors of Unit 1 to 3 was continued without interruption.
http://www.tepco.co.jp/en/press/corp-com/release/11072503-e.html

http://www.nikkei.com/news/latest/article/g=96958A9C93819595E0E7E2E2E78DE0E7E2E5E0E2E3E39790E0E2E2E2 however the spare equipment has only a 10 m³ / hour flow, while a 16 m³/ hour flow is required. Because there is not enough desalinated water, Tepco supplemented the tank for reactor injection with freshwater [from the dam ?]. Tepco also decided to decrease the flow injected into unit 3 from 9 m³/hour to 8 m³/hour.

http://www3.nhk.or.jp/news/html/20110725/t10014430861000.html as a result of taking water from the dam, the total amount of contaminated water is increasing.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110725_01-e.pdf diagram showing the broken down reverse osmosis system.

http://www.tv-asahi.co.jp/ann/news/web/html/210725016.html The desalinating facility trouble is resulting of a low pressure warning signal at a pump whose purpose is to wash the equipment [I guess, the backwash pump mentioned on page 2 of Tepco's diagram]. The facility has been restarted with two spare equipments resulting into treated quantity being cut by half.

http://mainichi.jp/select/weathernews/news/20110725dde007040051000c.html A pump in the sand filtration equipment stopped. The resulting flow after switching to backup equipment is about one half of the original 50 m³/ hour. [I wonder which I should believe : Nikkei's 10 m³/hour or Mainichi's about 50/2= about 25 m³/hour ? As both Nikkei and NHK report the produced quantity is not matching the needs, there must be some truth in it]

 

[zapperzero]

My understanding is that the RCIC turbine basically needs a difference of pressure. Did we reach a point when the pressure in the suppression chamber became so high that the steam flow in the RCIC turbine was not enough to move the turbine ?

Corrosion problems that were hidden by TEPCO (eventually triggering the 2002 scandal) were alsso found at Kashiwazaki in the recirculation piping. Maybe Fukushima suffered from the same issue and steam was escaping already? At least one of the units was reported to be "fogged in" very early on.

EDIT: take a look at this:
http://cnic.jp/english/newsletter/pdffiles/nit143.pdf
and this:
http://www.iasmirt.org/SMiRT17/WG01-1.pdf

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110718/0805_suiryou.html On 17 July afternoon, Tepco changed the pump that injects water into both unit 1 and unit 2 reactors. Its maximum flow rate is 20 m³/hour. On the morning of 17 July, the flow rate injected into unit 1 declined to about 3 m³/hour instead of the expected 3.8 m³/hour, ringing an alarm. The flow rate had to be ajusted again to 3.8 m³/hour. While nothing similar happened on the unit 2 line, it is the third time this sort of trouble happens at unit 1. For that reason it is believed that there is dirt in the piping to unit 1.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110725/0535_genshiro.html Three days ago (22 July) the flow rate into unit 2 declined to 3.4 m³/hour and to 3.2 m³/hour on 23 July. On 24 July, the flow rate into unit 1 declined to 3.3 m³/hour. This makes 3 flow decline incidents over the past three days. Each time Tepco adjusted the pump in order to recover the original flow rate. Tepco is reinforcing surveillance and investigating the cause.

 

[NUCENG]

"""If the suppression pool pressure rises to such heights that the steam flow won't move the RCIC turbine, couldn't you, as a last resort measure, vent the suppression pool into the atmosphere ? Steam engines don't need a cooling system provided you are allowed to release the steam into the atmosphere. """


I think i recall from the NRC report on extended blackout, using Brown's Ferry's specific plant design as a 'typical' example, that the RCIC steam turbine has a temperature switch to shut it down should ambient temperature reach 200F. Reason is that high ambient temperature infers a steam leak. I would guess that happened with no seawater to provide basic cooling to the plant.
http://www.ornl.gov/info/reports/1981/3445600211884.pdf
see page 63 of report, pdf page 75.

which presumes you can get into those rooms.


I never worked around a BWR - probably Nuceng knows way better than me.

old jim

You are correct, at least for BWRs here in the US. Standard Emergency Operating Procedures for BWRs include defeats to bypass both the low steamline pressure and room high temperature isolations for the RCIC system. There is no need to enter the room to activate these defeats as they are performed in control cabinets outside of the room. SBO procedures also include steps to open doors and install blowers to ventilate the room.

 

[tsutsuji]

Fukushima Daichi:

http://www.yomiuri.co.jp/science/news/20110725-OYT1T00933.htm IAEA director general Yukia Amano visited Fukushima Daiichi today : "The water treatment system's efficiency is pretty good for a performance without rehearsal".

I don't remember if the following article was already mentioned in this thread :

A former senior Tepco executive involved in the decision-making says there were two main reasons for removing the cliff. First, a lower escarpment made it easier to deliver heavy equipment used in the plant, such as the reactor vessels, turbines and diesel generators, all of which were transported to the site by sea. Second, the design of the plant required seawater to keep the reactor cool, which was facilitated by a shorter distance to the ocean.
12 July "Fateful Move Exposed Japan Plant: Tokyo Electric Lowered Elevation of Land Before Building Nuclear Facility, Weakening Tsunami Defense" http://online.wsj.com/article/SB10001424052702303982504576425312941820794.html

Tsuruga nuclear power plant unit 2:

fuel rod damage
http://www.fukuishimbun.co.jp/localnews/nuclearpower/29540.html (25 July) Japco released the result of the analysis of the 193 fuel assemblies from Tsuruga unit 2 reactor which was manually shut down in May after the discovery of radioactive substances in the cooling water. A leak was found in one assembly first loaded in August 2006. As the fibroscopy revealed no surface damage or abnormality with a 0.025 mm accuracy, it is thought that the leak occurs through random tiny pinholes. That assembly will no longer be used. Including this one discovered at Tsuruga, 5 out of 2,450,000 fuel rods of the same type used in Japan have been found with pinholes until now.

http://www.japc.co.jp/news/bn/h23/230725.pdf 25 July press release. Page 2 : fuel assembly sipping test. Page 3 : visual inspection (no abnormality revealed) - ultrasonic test to detect the presence of water inside the leaking rod - examples of fibroscopy pictures.
http://www.japc.co.jp/news/bn/h23/230506.pdf 06 May press release (reactor shutdown announcement)
http://www.japc.co.jp/news/bn/h23/230502.pdf 02 May press release (increase of radioactive substances in primary coolant water)

atmospheric release
http://www.47news.jp/CN/201107/CN2011072501000850.html On 8 May and on 21 May, very small quantities of radioactive gasses were released into the atmosphere through the exhaust stack.

http://www.japc.co.jp/tsuruga/news/info/20110509_tsuru2_haikitougasmoinita_joushou.html (http://www.japc.co.jp/tsuruga/news/pdf/110509_tsuru2__haikitougasmoinita_joushou.pdf) 9 May press release : 4.1 10$^{9}$ Bq were released. This is 400,000 times less than the yearly limit of 1.7 10$^{15}$ Bq for noble gasses.

http://www.japc.co.jp/tsuruga/news/info/20110521.html (http://www.japc.co.jp/tsuruga/news/pdf/110521tenpuzu.pdf) 21 May press release : 8.1 10$^{9}$ Bq were released. This is 200,000 times less than the yearly limit of 1.7 10$^{15}$ Bq for noble gasses. (yearly release in 2008 : below detection threshold ; yearly release in 2009 : 7.4 10$^{8}$ Bq).

http://www.japc.co.jp/tsuruga/news/info/20110712_1.html (http://www.japc.co.jp/tsuruga/news/pdf/20110712_1.pdf) 12 July press release about the atmospheric release causes and countermeasures.

fire
http://www.japc.co.jp/tsuruga/news/pdf/110518_tsuru2_gensuitanku_sagyoujino_hakka.pdf (18 May) a small fire broke out and was extinguished with a fire water bucket during anti-earthquake reinforcement work on the top of a freshwater tank (source for secondary coolant water or fire extinguishing purposes). A penetrant testing spray can was ignited during welding or grinding. Nobody was injured. There is no environmental consequence.

Tsuruga nuclear power plant unit 1 (under inspection since January) :

http://sankei.jp.msn.com/affairs/news/110712/dst11071221510025-n1.htm (12 July) A chemical (such as sulphuric acid) leaked from two locations on a pipe belonging to a liquid waste tank. On 18 June a worker found the leak with the chemical solidifying into an ice-lump like shape and a dried drop on the floor. The pipe will be changed. It had never been inspected since its installation in 1977. This is a very small radioactive leak inside the facility without consequence on the environment.

http://www.japc.co.jp/tsuruga/news/pdf/20110712_2.pdf 12 July chemical leak press release with pictures. The leak is located in the New waste treatment building.

The No. 1 reactor at the Tsuruga nuclear power plant in Fukui Prefecture does not have a vent to release excess pressure during a reactor emergency
4 July http://search.japantimes.co.jp/cgi-bin/nn20110704a2.html

 

[Atomfritz]

It is really sad that the big Hamaoka NPP probably will have to be dismantled due to bad siting even in spite of costly tsunami retrofitting.
I am sure it would have been way cheaper in the long run if they had been built on suitable sites with adequate quake/flood protection.

Anyway, reactors shouldn't be housed in cardboard boxes that pop open due to small hydrogen fireworks imho.

Corrosion problems that were hidden by TEPCO (eventually triggering the 2002 scandal) were alsso found at Kashiwazaki in the recirculation piping. Maybe Fukushima suffered from the same issue and steam was escaping already? At least one of the units was reported to be "fogged in" very early on.

Thanks for the links!

I agree with the conclusion of the CNIC writer.
This scenario is truly an unsolved safety risk, as quite a lot of the welds cannot be checked anymore after reactor went into operation.
In fact the safety estimates for life extensions are just guesses based on the correctness of old Tepco data. And so it's all some sort of gambling.

By the way, in the http://cnic.jp/english/newsletter/pdffiles/nit142.pdf" I found something that I didn't know of before.
Quote from pg. 8:
・The reactor buildings and turbine buildings for KK-1 to 7 have continued to rise and sink erratically
・The exhaust stacks are leaning to the side due to tilting of the foundations. This is most prominent at KK-1, 2 and 3

The Leaning Tower of Kashiwazaki-Kariwa:

This and Fukushima really could become big tourist attractions!

Edit:

Tsuruga nuclear power plant unit 1 (under inspection since January) :

http://sankei.jp.msn.com/affairs/news/110712/dst11071221510025-n1.htm (12 July) A chemical (such as sulphuric acid) leaked from two locations on a pipe belonging to a liquid waste tank. On 18 June a worker found the leak with the chemical solidifying into an ice-lump like shape and a dried drop on the floor. The pipe will be changed. It had never been inspected since its installation in 1977. This is a very small radioactive leak inside the facility without consequence on the environment.

http://www.japc.co.jp/tsuruga/news/pdf/20110712_2.pdf 12 July chemical leak press release with pictures. The leak is located in the New waste treatment building.

Possibly the visual inspections, if any, were also very superficial. The waste safety seems not to be taken as serious as necessary, no matter where on the world.
More than third of a century without thorough inspection... mad!
Probably the nuclear industry needs a civil SFP Kyshtym to wake up...

 

[tsutsuji]

・The exhaust stacks are leaning to the side due to tilting of the foundations. This is most prominent at KK-1, 2 and 3

The Leaning Tower of Kashiwazaki-Kariwa:

This and Fukushima really could become big tourist attractions!

Let alone potential http://en.wikipedia.org/wiki/Distortion_%28optics%29" , an unidentified and undated picture of Kashiwazaki Kariwa's units 5-6-7 is a rather weak evidence of leaning being "most prominent at KK-1, 2 and 3".

The following picture of units 5-6-7, dated 18 June 2008 : http://www.flickr.com/photos/27893064@N06/2853437602/in/photostream is showing the same stack, but leaning the opposite way. In my opinion this is nothing more than photographic distortion.

Here is a picture dated 3 April 2011 http://ja.wikipedia.org/wiki/ファイル:Kashiwazaki-Kariwa_Nuclear_Power_Plant.jpg where all stacks seem vertical.

 

[MiceAndMen]

By the way, in the http://cnic.jp/english/newsletter/pdffiles/nit142.pdf" I found something that I didn't know of before.
Quote from pg. 8:
・The reactor buildings and turbine buildings for KK-1 to 7 have continued to rise and sink erratically
・The exhaust stacks are leaning to the side due to tilting of the foundations. This is most prominent at KK-1, 2 and 3

The Leaning Tower of Kashiwazaki-Kariwa:

This and Fukushima really could become big tourist attractions!

The linked newsletter does mention those points on page 8, but that photo does not appear in the newsletter at all. What that photo displays IMO is nothing more than optical distortion.

 

[Atomfritz]

Let alone potential http://en.wikipedia.org/wiki/Distortion_%28optics%29" , an unidentified and undated picture of Kashiwazaki Kariwa's units 5-6-7 is a rather weak evidence of leaning being "most prominent at KK-1, 2 and 3".

You are right, this photo is not really suitable as proof.
It is in fact a very small part of http://2.bp.blogspot.com/_b5hcKABPlGI/RqA9vnjdshI/AAAAAAAAD2s/72ODBAMI9zc/s1600-h/0712l.jpg".
I didn't find a map with a legend what unit stands where, so I supposed the smaller ones are the older ones.

 

[LabratSR]

http://www.ornl.gov/info/reports/1981/3445600211884.pdf

Interesting to note that Sherrell Greene, from the interview I posted above, is one of the authors of this document.

 

[Atomfritz]

Corrosion problems that were hidden by TEPCO (eventually triggering the 2002 scandal) were alsso found at Kashiwazaki in the recirculation piping. Maybe Fukushima suffered from the same issue and steam was escaping already? At least one of the units was reported to be "fogged in" very early on.

EDIT: take a look at this:
http://cnic.jp/english/newsletter/pdffiles/nit143.pdf
and this:
http://www.iasmirt.org/SMiRT17/WG01-1.pdf

Let's go back to the central point of the article published in the CNIC newsletter you linked at.
It's written by an ex-RPV designer and looks very competent to me.

The "unsolved safety problem" (as at least NRC etc name it) that this man describes explains the phenomenon of the high D/W pressure very well. Remember, it was almost double of planned maximum pressure.
His explanation also might also give a good picture why so much hydrogen leaked outside primary containment.

The crucial point that the nuclear industry does not want people to know is that the accident possibly was caused by primary containment tube break, and not by the tsunami.

To understand this, look at this picture from page 3 from http://cnic.jp/english/newsletter/pdffiles/nit115.pdf" :

(for higher res image please use source link)

You see, 1F1 embrittlement has already been very high.

Now consider the combination of earthquake stress, embrittlement and another important factor, metal thinning, that the nuclear industry does not like to talk about.

Look at this picture:

(http://cnic.jp/english/newsletter/pdffiles/nit103.pdf" )
This tube ruptured in the Mihama-3 accident that fried 11 workers with hot high-pressure steam, four of them dying.
Quotes from accident reports:

"A main condensate pipe in the secondary coolant system had ruptured. The pipe contained water heated to 140 degrees Celsius under 9.5 atmospheres pressure. When the pipe ruptured, this water spewed out in the form of steam, severely scalding the unfortunate workers who happened to be in the room. The thickness of the wall of the pipe at the point where it ruptured was down to around 1mm, compared to the original thickness of 10mm and the regulatory minimum of 4.7mm. It had never been checked during the entire 28 years that the plant had been operating"
​

(highlighting by me, source: http://cnic.jp/english/newsletter/pdffiles/nit102.pdf" )

Official analysis (http://cnic.jp/english/newsletter/pdffiles/nit106.pdf" ) says:

"Final Reports on Mihama-3 Accident:
...The NISA and NSC reports both fail to answer the questions of when KEPCO became aware that the pipe had not been inspected, when it became aware that some locations had not been included on the inspection list, and whether remaining life expectancy assessments had been made."​

Maybe there are many more never-visited locations in the NPPs that never have been inspected since inauguration and we only see tip of iceberg.

There is just one thing for sure:
The nuclear industry obviously doesn't want people to know of aged, brittle and thin-walled reactors that are in permanent danger of bursting open due to a plethora of possible causes.

In Germany already some old reactors had to be retrofitted with ECCS water preheating, just to avoid the RPV eventually bursting only because of using "normal" ECCS with unheated water.

 

[tsutsuji]

http://news24.jp/articles/2011/07/14/07186434.html and http://news.tbs.co.jp/newseye/tbs_newseye4775950.html ( ) [14 July] The new water treatment facility, called "[SARRY]" left Yokohama Port this morning. Its start is planned for next month. [SARRY] is made by Toshiba, IHI and US company Shaw. Its decontamination factor is up to one million. According to Toshiba, it can be used as a backup of the Kurion-Areva system.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110726/0535_shinsouchi.html I have no definite proof that it it the same ship or exactly the same shipment or why it made a call at Onahama Port if it is the same ship, but the first of two shipments of cylindrical tanks for the new SARRY system left Onahama Port yesterday evening and it is planned to arrive at Fukushima Daiichi today. SARRY consists of 14 cylindrical tanks filled with a cesium filtering mineral inside. It can be used either in parallel or in combination with the other system.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110726/0530_sekkeimiss.html The desalination facility's trouble was the consequence of a pump setting mistake based on a wrong assumption of a tank water level. The system fully recovered at 01:00 AM this morning after correcting the wrong setting.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110726/index.html At 09:30 PM yesterday, a worker found out that 1 out of 4 Kurion system pumps was down. That pump was restarted 30 minutes later. Tepco has no idea when it stopped. This incident had no consequence on the cooling of reactors.

http://www.flickr.com/photos/iaea_imagebank/5765318454/sizes/l/in/photostream/ a large size picture of the unit 5-6 water intake collapsed crane. The triangle structure behind the truck is the crane's http://www.houseoffoust.com/fukushima/tepco_pics/r6_waterpump4.jpg broken leg which could not be seen on http://www.netimago.com/image_202944.html .

 

[tsutsuji]

You are right, this photo is not really suitable as proof.
It is in fact a very small part of http://2.bp.blogspot.com/_b5hcKABPlGI/RqA9vnjdshI/AAAAAAAAD2s/72ODBAMI9zc/s1600-h/0712l.jpg".
I didn't find a map with a legend what unit stands where, so I supposed the smaller ones are the older ones.

The unit numbers from south to north (or looking at the sea) are 1-2-3-4-7-6-5. A map is available on page 5 (pdf page number 6) of http://www.nsc.go.jp/senmon/shidai/shisetsuken/shisetsuken057/siryo4.pdf .

I found the following :

http://www.nsc.go.jp/senmon/shidai/shisetsuken/shisetsuken057/siryo4.pdf Tepco report, dated 13 December 2010, presenting the results of the inspection of Kashiwazaki Kariwa unit 3 exhaust stack.

On page 13 (pdf page number 14) they say they use the standard set by the Architectural Institute of Japan for the assessment of the damages of the 1995 Kobe earthquake. According to that standard, the maximum allowed inclination for unit 3 stack is 1/300 and the maximum allowed sinking is 50 mm.

On page 15 (pdf page number 16) they say they measured a 1/2200 inclination and a maximum sinking of 13.9 mm, therefore the standard is satisfied.

Cracked foundation piles
KK-3's exhaust stack has 52 foundation piles. Only four of these have been checked and cracks were found in all four. The biggest crack was 2mm wide and 2.08mm long. Kotaro Kuroda, a member of the subcommittee on equipment integrity and seismic safety, suggested that this should be assessed as level IV damage, but TEPCO assessed it as level II on the grounds that there was no exfoliation. One wonders about the condition of the other foundation piles. Clearly they should be checked.

http://cnic.jp/english/newsletter/nit140/nit140articles/kk.html or page 2 http://cnic.jp/english/newsletter/pdffiles/nit140.pdf jan/feb 2011 ; the 2mm wide and 2.08mm long crack data are available on page 16 (pdf page number 17) of http://www.nsc.go.jp/senmon/shidai/shisetsuken/shisetsuken057/siryo4.pdf

http://www.tepco.co.jp/nu/material/files/k09071501.pdf report dated 15 July 2009 about the unit1-unit2 exhaust stack. Page 4-6 (pdf page 12) : The measured inclination (1/2000) and the sinking (16.8 mm) are both satisfying the standard.

http://www.nsc.go.jp/senmon/shidai/shisetsuken/shisetsuken032/ssiryo3.pdf　report dated 7 December 2009 about unit 5 exhaust stack. Page 4-6 (pdf page 12) : inclination 1/13,000 and sinking 2.3 mm.

http://www.nsc.go.jp/senmon/shidai/shisetsuken/shisetsuken008/siryo8.pdf 10 October 2008 report on the inclination of buildings. The worst one is unit 6 control room, with 1/4000 but this is below the 1/2000 standard applying to those buildings (pages 2 and 3 - pdf page numbers 3 and 4).

http://www.tepco.co.jp/nu/material/files/g08071003.pdf Pages 4 and 5 (pdf page numbers 5 and 6) show the damages to two lightning attraction towers' diagonal bracing.

 

[MJRacer]

_

I am not impressed with CNIC's sourcing practices. Reading some of the linked reports, there are multiple unsourced references. The http://cnic.jp/english/newsletter/pdffiles/nit103.pdf publication which reports on the Mihama pipe rupture as mentioned above is one example. I have tried to source the diagram of the pipe thinning and I believe that I have found what may be the original source document from which this image was created. Please see http://www.atomdb.jnes.go.jp/content/000025568.pdf , page 66. It looks like the image in the CNIC document of the cross-section of piping may have been created by combining 2 or more of the images on that page. Lack of sourcing lowers credibility, IMHO. In this case, though, I may have found the source.

The Alaska pipeline has been "pigged" using smart pigs more than 60 times. Smart pigs use Ultrasonic Transducing, Magnetic Flux Leakage Detection and Curvature detection on the Alaska pipeline. Please see http://www.dec.state.ak.us/spar/perp/response/sum_fy11/110108301/factsheets/fact_Pigging.pdf.

Pipelines are specifically designed to be pigged. I am not sure that Nuclear Power Plants, however, are so designed (I don't think smart pigs were in existence when some of these plants were built). In principle, pigging using smart pigs permits 100% inspection of the full length of piping, especially critical piping that may not be easily accessible. Obviously, implementing a pigging program in a plant that was not designed for it would present a number of challenges. Among them would be I would think radiation hardening (smart pigs are electronic devices), launching/retrieval issues, fittings that might prevent passage of the pigs and so forth. Does anyone know if this has been tried in practice?

 

[joewein]

I had always assumed the roof had come off the roof girders in unit 4 at the same time the panels were blown out, but apparently not so. http://www.isis-online.org/isis-reports/detail/new-satellite-image-of-fukushima-daiichi-nuclear-site-in-japan-from-march-1/" shows the damaged building but with the roof girders still covered.

 

[westfield]

I had always assumed the roof had come off the roof girders in unit 4 at the same time the panels were blown out, but apparently not so. http://www.isis-online.org/isis-reports/detail/new-satellite-image-of-fukushima-daiichi-nuclear-site-in-japan-from-march-1/" shows the damaged building but with the roof girders still covered.

It's seems to be an illusion because there are quite a few March 16 shots that show "normal" Unit #4. (that reads like a tepco press release - yes , the roof is still not there so Unit 4 is nominal.)

Like this capture from the March 16 SDF Chopper footage - source tepco.

 

[joewein]

It's seems to be an illusion because there are quite a few March 16 shots that show "normal" Unit #4. (that reads like a tepco press release - yes , the roof is still not there so Unit 4 is nominal.)

Like this capture from the March 16 SDF Chopper footage - source tepco.

The image I came across may have been right at the margin of the satellite camera resolution. Here's best version of the DigitalGlobe image I could find:

http://upload.wikimedia.org/wikipedia/commons/7/7d/Fukushima_I_by_Digital_Globe.jpg

 

[Bandit127]

2 videos of International Atomic Energy Agency (IAEA) head, Yukiya Amano visiting Fukushima Daiichi.

The first is an interview against a backdrop of workers being assessed for contamination.
http://www.youtube.com/watch?v=cX_0VYScSms&feature=relmfu"

The second (over 6 minutes) is of a plant tour.
http://www.youtube.com/watch?v=bA1jojWGt4k&feature=relmfu"

 

[Atomfritz]

The image I came across may have been right at the margin of the satellite camera resolution. Here's best version of the DigitalGlobe image I could find:

http://upload.wikimedia.org/wikipedia/commons/7/7d/Fukushima_I_by_Digital_Globe.jpg

You are right.
Bandwidth issue. Roof girders apparently too small to be displayed. Resulting in dirty grey. This phenomenon is even aggravated by non-integer scaling.

Look at the vertical diagonal girders of #1 on the same pic:

You see the bandwidth problem. The X looks more like the 5 on a dice.
And. you clearly can recognize the debris on #4 roof that is not aligned with the ceiling bars.

However, look closely at the satellite photo that has been taken several hours before the helicopter film.
The rightmost three steel pillars (NE side) are clearly bent outside, way more than you can recognize in the satellite photo. So it seems reasonable for me to assume that in the aftermath of the explosion the building and the debris settled/moved for some time until getting (temporarily) stable.

 

[Atomfritz]

I am not impressed with CNIC's sourcing practices. Reading some of the linked reports, there are multiple unsourced references. The http://cnic.jp/english/newsletter/pdffiles/nit103.pdf publication which reports on the Mihama pipe rupture as mentioned above is one example.

This is true. But as nuclear society is closed society, investigators like CNIC need help from inside informers.
So it is often not possible to reveal the source to protect the leakers of nuclear secrets.

I have tried to source the diagram of the pipe thinning and I believe that I have found what may be the original source document from which this image was created. Please see http://www.atomdb.jnes.go.jp/content/000025568.pdf , page 66. It looks like the image in the CNIC document of the cross-section of piping may have been created by combining 2 or more of the images on that page. Lack of sourcing lowers credibility, IMHO. In this case, though, I may have found the source.

Thank you very much for your effort. This is a very long document with much meaningless "information" for the public. Very interesting, see below.

However, it is probably not the source for the CNIC information.
The picture in the CNIC newsletter seems to be high-resolution, very exact and professionally annotated, probably photographed from an internal (non-public) report.
The scan on the document you found in contrast very coarse-grained and incomplete, to be of limited use of the public.
And, the diagrams on the public document are way less illustrative than the drawing intended only for "nuclear insiders".

However, the really important parts of the document are revealing. See Chapter 4:

4. Investigation of pipe wall thickness control
[...]
(2) Validity of PWR Management Guidelines
For the PWR Management Guidelines, more than 10 years have passed since the
establishment, and a lot of thinning data has been obtained. Nevertheless, no review has
been done based on the latest data.
[...]
This time, actual values of the thinning rate based on
the data obtained by the inspections so far, described later, at nuclear power plants
throughout the country were analyzed, and it was found that these values are less than the
initially set value of thinning rate prescribed in the PWR Management Guidelines except
for only a few of them. Therefore, the initially set value of thinning rate prescribed in
the Guidelines can be assessed to be valid in principle.

Selection of sampling points
For the portions showing no tendency of thinning, the PWR Management Guidelines
stipulate inspection of those portions at a rate of about 25% every 10 years
​

It is very interesting to read this.
Such a long document just to hide the fact that profits go before safety.

We now know that a big part of our NPPs never gets examined.
This regards a big part of the primary circuit.
There just tests of other locations are being interpolated, and if this interpolation is satisfiable, then "tests" are passed without actually testing the tubing in question, or even knowing its state.

The nuclear industry and "regulation" says: Because our method of "testing" is valid in principle, we are correct and no changes are necessary.

We Krauts have a proverb: "Die Ausnahme bestätigt die Regel." (The exception confirms the rule.)
So you basically cannot be sure if you only interpolate instead of actually looking/measuring what's there.

You always have to expect that possibly something unusual/irregular could happen. You cannot conclude that nothing is wrong without actually checking, just because the probability that something is wrong is only 1%.Just another example: Davis-Besse RPV "passed" so-called "tests" over years while actually almost breached, etched through. leaving only the thin stainless steel layer as protection from an uncontrollable accident.
Remember, the problem was discovered only by somebody who was so bright not to regard the massive stains of leaking boric acid as "unimportant", as his colleagues did for years.
(See http://iweb.tms.org/NM/environdegXII/0855.pdf" for many illustrative photos)

And with this "regulation" the nuclear industry does not even need to lie: "We did all checks necessary by regulations" when in fact checking almost nothing of real safety relevancy.

Pipelines are specifically designed to be pigged. I am not sure that Nuclear Power Plants, however, are so designed (I don't think smart pigs were in existence when some of these plants were built).

In principle, pigging using smart pigs permits 100% inspection of the full length of piping, especially critical piping that may not be easily accessible. Obviously, implementing a pigging program in a plant that was not designed for it would present a number of challenges. Among them would be I would think radiation hardening (smart pigs are electronic devices), launching/retrieval issues, fittings that might prevent passage of the pigs and so forth. Does anyone know if this has been tried in practice?

Nuclear plants are not designed for pigging.
In fact, pigging is used there only as the very last resort, if there is nothing to be lost anyway.

Several reasons:
Pigs are difficult to use around corners because you have to open the tubing if the pig gets stuck.
However, tubing in NPPs has many turns, making pigging extremely risky.
One stuck pig = massive, expensive repair work creating lot of outage time.

And, tubing diameters are not continuous. You have ups, downs, turns, orifices, varying diameters, etc. Many opportunities for problems with pigs.

Usually tube checking is done with ultrasonic or X-raying at a few points, at least in Germany.
And, please don't forget the tendency in the nuclear industry to just protocol some random "acceptable" values if the real measurement results do not satisfy!

(I have this information from a newspaper interview with a nuclear engineer; the reporter asked the engineer why there were not used pigs to examine tubing. It was after some aging German reactor had to be shut down because deep cracks were accidentally detected in primary circuit feedwater lines. This was before the Internet age, so it may be difficult to find the source. Maybe Astronuc or Nuceng can confirm the information.)Edit:
P.S.: After I wrote this, I remembered that I really never understood by what means people at http://en.wikipedia.org/wiki/Enrico_Fermi_Nuclear_Generating_Station" found out that there was a piece of Zirconium cladding at the bottom of the reactor, blocking coolant circulating and causing partial meltdown.
Sodium is opaque and the "part" officially being the cause of the accident was at the bottom of the reactor vessel, below the molten core.
So, I ask myself, how did they find this out?

 

[jmelson]

P.S.: After I wrote this, I remembered that I really never understood by what means people at http://en.wikipedia.org/wiki/Enrico_Fermi_Nuclear_Generating_Station" found out that there was a piece of Zirconium cladding at the bottom of the reactor, blocking coolant circulating and causing partial meltdown.
Sodium is opaque and the "part" officially being the cause of the accident was at the bottom of the reactor vessel, below the molten core.
So, I ask myself, how did they find this out?

They had to build a massive facility to offload the liquid sodium into drums under a nitrogen atmosphere, then they were finally, about a decade later, able to lower cameras into the reactor to observe what the problem was. The part that broke loose and wedged into the core was not even on the drawings, but was added days before the design was locked in, to spread a melt-down and prevent pooling of melted fuel.

There was a book called "we almost lost Detroit" about this and other accidents. It is extremely breathless "journalism" but if you read through that stuff, it has a lot of good info that wasn't easily available anywhere else at the time I read it.

Jon

 

[tsutsuji]

- At 2:45 PM on July 26, TEPCO's employee who moved from Fukushima Daini
Nuclear Power Station to Fukushima Daiichi Nuclear Power Station and had
driven a vehicle in the site with wearing full face mask, noticed that
the charcoal filter was not installed on the full face mask when the
worker came back to the Main Anti-Earthquake Building. As the result of
dose evaluation of internal exposure, we confirmed that no affect on the
body.
http://www.tepco.co.jp/en/press/corp-com/release/11072703-e.html

http://www.fnn-news.com/news/headlines/articles/CONN00204177.html 11 people have been sent to unit 3's reactor building. Their mission is to inspect the piping on the second and third floors as part of a plan to create an alternative water injection route which might be more efficient than the present one which requires a 9 m³/hour flow and is a major source of accumulating contaminated water. It is a difficult work because in some places in this reactor building radiations up to 75 mSv/hour are observed. A pump in the megafloat low contaminated water filling system has been found leaking, and the system had to be shut down, but there is no radiation released outside or into the sea.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110727/index.html Today's manned mission is the result of yesterday's robot mission that showed that unit 3's piping and valves were little damaged. 6 people are going to the second and third floors.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110727_01-e.pdf robot Quince's yesterday mission.

 

[tsutsuji]

I am not impressed with CNIC's sourcing practices. Reading some of the linked reports, there are multiple unsourced references. The http://cnic.jp/english/newsletter/pdffiles/nit103.pdf publication which reports on the Mihama pipe rupture as mentioned above is one example. I have tried to source the diagram of the pipe thinning and I believe that I have found what may be the original source document from which this image was created. Please see http://www.atomdb.jnes.go.jp/content/000025568.pdf , page 66.

I tried to see if could find something, but I didn't find anything much interesting apart from a few photographs that were released to the press :

[PLAIN]http://www.atomdb.jnes.go.jp/content/000018631.jpg
From http://www.atomdb.jnes.go.jp/events-data/events-001585.html

[URL]http://www.fukuishimbun.co.jp/jp/mihamaziko/0811b.jpg[/URL]
From http://www.fukuishimbun.co.jp/jp/mihamaziko/kiji1.htm (11 August 2004)

[URL]http://www.fukuishimbun.co.jp/jp/mihamaziko/0811bb.gif[/URL]
From http://www.fukuishimbun.co.jp/jp/mihamaziko/kiji1.htm (11 August 2004)

Kepco inspected other facilities and replaced the pipes at the Takahama Nuclear Power Plant's No. 3 reactor and Oi Nuclear Power Plant's No. 1 reactor, both in Fukui Prefecture, with stainless steel ones between 1998 and 2003 because they had worn so thin that they would not last another two years, the sources said.
http://search.japantimes.co.jp/cgi-bin/nn20040811a1.html

 

[gmax137]

...
P.S.: After I wrote this, I remembered that I really never understood by what means people at http://en.wikipedia.org/wiki/Enrico_Fermi_Nuclear_Generating_Station" found out that there was a piece of Zirconium cladding at the bottom of the reactor, blocking coolant circulating and causing partial meltdown.
Sodium is opaque and the "part" officially being the cause of the accident was at the bottom of the reactor vessel, below the molten core.
So, I ask myself, how did they find this out?

...
There was a book called "we almost lost Detroit" about this and other accidents. It is extremely breathless "journalism" but if you read through that stuff, it has a lot of good info that wasn't easily available anywhere else at the time I read it.

Jon

Here's a book with more detail than you probably want (and it's not 'breathless' by any means):

https://www.amazon.com/dp/0894480170/?tag=pfamazon01-20

 

[tsutsuji]

http://www.yomiuri.co.jp/science/news/20110728-OYT1T00524.htm The water treatment utilization rate for last week is hardly better than before with 58%, far from the 70% (originally 90%) target. The over-all average since the beginning is 63%. 29,000 tons have been processed so far.

http://www.at-s.com/news/detail/100048546.html (Shizuoka Shimbun) It was revealed today that the only one remaining fuel assembly in Hamaoka unit 1 (under decommissioning) 's spent fuel pool is the very fuel assembly that caused a radiation leak incident in 1994. According to a nuclear power administration related source, this is not the only plant in Japan because transporting damaged fuel is an unsolved problem. As no rule has been decided concerning the processing of damaged fuel, the country's regulatory complacency is also emerging. In December 1994 that fuel had pinholes, causing an exhaust gasses radiation alarm and a manual shut-down of the plant. While being myriads of times lower than the yearly allowed limit, this exhaust radiation level was abnormal. In October 1990 five damaged assemblies were found. One was sent to Nippon Nuclear Fuel Development Co. in Oarai, Ibaraki prefecture, and the other 4 were sent to British Nuclear Fuels. In 1994 NNFD said "pinhole damaged fuel is difficult to research" and BNF said "contract has reached its term". Chuden plans to move the damaged fuel assemblies from units 1 and 2 into the unit 4 and unit 5 spent fuel pools by the end of 2013 fiscal year, and is now studying what sort of consequences such a transportation might bring and if countermeasures are needed. (http://www.atomdb.jnes.go.jp/events-data/events-000581.html Hamaoka 1 1994 pinhole incident - INES level 0) (http://www.atomdb.jnes.go.jp/events-data/events-000198.html 1990: 5 assemblies found leaking, 78 assemblies found with abrasion. INES Level 1. Found during inspection. No radiation consequence on the environment).

 

[NUCENG]

This is true. But as nuclear society is closed society, investigators like CNIC need help from inside informers.
So it is often not possible to reveal the source to protect the leakers of nuclear secrets.
...
And, the diagrams on the public document are way less illustrative than the drawing intended only for "nuclear insiders".
And with this "regulation" the nuclear industry does not even need to lie: "We did all checks necessary by regulations" when in fact checking almost nothing of real safety relevancy.

Pipe Rupture occurred on Aug 9, 2004.

NISA Interim Report Sep 27, 2004

http://www.atomdb.jnes.go.jp/content/000025567.pdf

NISA Final Report March 30, 2005

http://www.atomdb.jnes.go.jp/content/000025568.pdf

CNIC Report Nov Dec 2004

http://cnic.jp/english/newsletter/pdffiles/nit103.pdf

Where is the evidence of secrecy in that timeline? The lack of adequate inspections was identified shortly after the event and resulted in plant shutdowns across Japan. I am not defending the utilities that weren’t performing required inspections, nor am I defending Japanese regulators for their failure to look further than shroud cracks at TEPCO a couple of years earlier. But your conspiracy theory of secrecy on this issue seems to be blown. CNIC did not discover this problem. It was discovered by the workers who were injured and killed. That is definitely not the approved method.

Mihama pipe rupture was not unique to nuclear plants. Do a little research on pipe ruptures due to flow accelerated corrosion and you will find other fatalities. You ignore the increased inspections and reviews from plants across the world as a result of Mihamas accident.

You also raise the specter of Davis Besse. First, there was no whistle blower. The problem was found when a worker found he could "wiggle" the CRDM. The lessons learned from the shutdown order and fines were severe and resulted in replacement of reactor vessel heads at many PWR plants. Even NRC came in for a lot of corrective action as a result of that event.

In short , you should probably be a little more sure of your facts on this forum, because there are people here that won’t let you get away with unfounded claims.

 

[LabratSR]

TEPCO to sample the air in the containments of units 1 and 2

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110728_02-e.pdf

 

[Joe Neubarth]

TEPCO to sample the air in the containments of units 1 and 2

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110728_02-e.pdf

That should be very interesting. Very interesting indeed.