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June 2012 Incidents

June 2012 Incidents

 

27/6/2012 - State of Restauration Works on the Accident Site

The TEPCO has published a series of pictures documenting the state of restauration works on the Fukushima accident site.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120626_02-e.pdf

 

25/6/2012 - Low Reliability of Fire Trucks

The TEPCO final accident report (Attachment) reveals a surprisingly low reliability of the fire trucks used for mobile injection. The figure shows the situation on 3/14/2011

14 fire trucks are on site. 3 fulfill the mission of mobile injection of sea water, 6 are in stand-by and 5 have failed, which means that 5 out of 14 have failed within 3 days! This fact should lead to a reevaluation of the reliability of the mobile injection in the ENSREG Stress Test.

23/6/2012 - Anti-siphon devices in Fukushima SPF

Shortly after the Fukushima accident the admin presented a hypothesis claiming the hydrogen originated at least partly from the Spent Fuel Ponds (SPF). It was hypothized that the SPF water level decreased substantially leading to insufficient cooling of the fuel elemets. This would have been definitely the case if the SPF in Fukushima had not been equipped with anti-siphon devices. The Admin's presentation can be found here. In the presentation all details are given and the anti-siphon effect is explained. The presentation inspired many nuclear experts to investigate the installation of anti-siphon devices in their domestic NPPs. French experts found this device was missing in Cattenon.

In the TEPCO final accident report (Attachment) schematic figures of the SPF cooling system are shown, in which the feed lines are equipped with check valves serving as anti-siphon devices. This information is new and was not presented in the Interim Report.

If the admin did not mess with the translation, the next figues show the SPFs of unit 1 - 4.

Unit 1

Unit 2

Unit 3

Unit 4

 

Admin's Comment: The admin is glad TEPCO now pays attention to the anti-siphon device. The admin is still not sure that anti-siphon devices had been in stalled. It is remarkable that all valves in the schematic drawings are labelled with their proper system name or number except for the the check valves in the SPF feed lines. These are not labelled with their proper system number but with "check valve" only. The check valves are presented in the correct direction different from the NRC drawing in which the direction of the check valves is wrong (check valves now are closed by reverse flow). This wrong direction in the older drawings originates from a mistake made in the 80's and wich has been continously copied. Thus the assumption is justified that the check valves have recently been inserted by someone who has read the presentation mentioned above.

 

23/6/2012 - Fire Truck Mistery solved

In the TEPCO final accident report (Attachment) detailed information on the role of the fire trucks ( and the complete failure of the mobile injection) is found on page 434 ff. The role of the fire trucks is presented in form a comic book. Page 434 shows the initial situation:

At the arrival of the tsunami 3 fire trucks were stationed at the plant: No 1 in a garage on the hill, the only one to survive the tsunami undamaged, No 2 was at the shore site and disappeared in the tsunami, No 3 was stationed closed to unit 5/6: fate unknown. That means: the plant with 6 units had only three fire trucks and not 6 or 12! Only one was available but had difficulties to reach the injection point at the corner of the Turbine Building facing the sea (!) - red points. This one was used to save unit 1 but failed as it took to long to install the mobile injection.

ON 3/12 at 10:30 three more fire trucks arrived on scene but all forces were focussed on unit 1. It was not berfore 3/13 at 9.25 that mobile injection in unit 3 was started (too late!)

The admin recommends flipping through these pages of the report. You do not have to read Japanese, it is like reading a comic book: 1F means Fukushima plant 1, 2F means Fukushima plant 2, KK means Kashiwasaki-Kariwa, which is a nuclear power plant at the same latitude as Fukushima but on the other (western) shore and the single Japanese letter 自 which looks like ladder with a man on top is the sign for the municipal fire fighters.

Admin comment: As I wrote before in the TEC-Sim report, the failure of the mobile injection is not due to the tsunami damage at the plant but to the failure to cope with the consequences caused by lack of equipment and training. It has happened in Fukushima and the same will happen in all countries which do not take the mobile injection serious.

Admin home work for the reader:

1. How many fire trucks can be bought with the bonus of the top TEPCO manager in 2010?
2. How many fire trucks can be bought with the 2012 bonuses of the EON, RWE, ENWB and Vattenfall managers in 2011?
3. How many years does the reader have to work for the same amount of money?

20/6/2012 - TEPCO final accident report released

TEPCO has released the final version of the accident report, unfortunately in Japanese only, but Google Tranlate will help. The final report differs from the interim accident report substantially. The appendix listing all changes has 54 pages.

http://www.tepco.co.jp/en/press/corp-com/release/2012/1205638_1870.html 

Most interesting is

-Fukushima Nuclear Accidents Investigation Report (Appendix-2) Schedule(Time series) (PDF 3.22MB)
-Fukushima Nuclear Accidents Investigation Report (Attachment) (PDF 32.2MB)

which contain many technical details.

The Admin will comment on the final report soon.

14/6/2012 - Puzzling radiation levels on unit 2 floor 5

TEPCO has investigated the changes of the radioation levels on the 5th floor od unit 2 by a small rorboter. though the roboter coud not detect any significant damage, the measured radiation levels are puzzling.

The figure shows the new (red) values in comparison with data obained by an earlier inspection. Observed maximum is 880 mSv/h in the middle of the containment cover. This finding is rather puzzling since ther is no penetration and no visible damage from which the high level may originate.

TEPCO considered building a higher tsunami wall in 2006

In the wake of the Christmas Tsunami 2004 TEPCO analyzed the the question what-if: What would be the tsunami height if the Christmas tsunami would have occurred in Fukushima: TEPCO came up with a calculation showing tsunami as high as 15.7 meters could strike the Fukushima plant while the design tsunami was only 5.7 m. TEPCO also calculated the costs and preferred not to build a tsunami wall capable to withstand a tsunami of this height. The rest is history.

Admin's comment: While evereybody is shaking his head in view of this short-sighted Japanese, they forget that they are of the same make: It is very easy to protect the exsisting NPPs against terroristic attacks by commercial airliners by constructing a concrete wall around the NPP. This wall exploits the fact, that comercial airliners cannot descend at an angle of more than 15 degrees. This wall would cost only a reasonable amount of money in view of the cost of a severe accident.

10/6/2012 - Few Anti-Nuclear Objectors at Public INput Meeting

German voters and objectors to nuclear energy are confronted with the strange phenomenon of the Green Party leaders focussing on political positions and power and not longer being interested in fighting the threats of nuclear energy.

The recent event in Passau demonstrates this change of the Green Party:
The Chech unitility CEZ is planning to build two new nuclear reactors in Temelin close to the German border. As an friendly gesture towards the German neighbours and not required by rules and regulations, CEZ has organised a public meeting in Passau to allow German citizens to give their input as part of the public involvement in the site selection. The site report elaborated as part of the license application process had been published before on the internet in German. On June 5th, 2012 CEZ had rented a multi-purpose hall in Passau with 3.600 seats. CEZ came with 30 Chech nuclear experts and found about 30 objectors lost in the giant hall. Even the Chech vice-minister of Environment had come to convince the audience. He was not impressed nor amused.

Admin's comment: Where have all these people gone, long time passing, where have all these people gone, long time ago, .........

12/6/2012 - Volatile fission products below detection limit

TEPCO has send workers into the torus of unit 2 for infrared measurement of the exterior condensation chamber wall temperatures and found temperatures about 40°C. Some picture show a horizontal jump in temperatures and TEPCO argues these indicate the water level inside.

Admin's comment: Basically  a horizontal temperature jump can indicate the water level inside but the jump has to be in an undisturbed part of the surface. The jumps in the photo are connected with structures on or before the vessel wall and this is not a reliable indicator.

TEPCO has carried out a nuclide analysis of radioactive materials (I131, Cs134 and Cs137) in the air on the upper part of the unit 2 and 3 reactor building and has found values below the detection limit.

TEPCO has carried out gas samplings for I131, Cs134 and Cs137 in the gas control system of the drywell (containment vessel) gas control system and has found values below detection limit.

Admin's comment: These fission products are called volatile because they escape easily into the enironment and that is what these volatile fission products have done.

10/6/2012 - Protection platform installed on unit 4 SPF

TEPCO has installed a steel platform as protection of unit 4 spent fuel pond. Recent fotos of unit 4 SPF have shown that TEPCO workers have been removing heavily damaged components and structures e.g. the crane and concrete beams to clear the area around the  SPF. They  had also placed heavy machinery there. The admin was highly concerned any accident dropping machinery or heavy parts into the SPF might lead to a large radioactive release.

Now this danger has been eliminated. Why TEPCO did not place a protection platform on the SPF at the beginning of the removal works is left unexplained. TEPCO is planning to remove the more intact structures of the 5. floor next to clear the floor for the construction of a controlled shelter for the removal of the fuel elements from unit 4 SPF.

7/6/2012 - Inspection of torus in unit 2 and 3

TEPCO workers have entered the torus of unit 2 and 3 for visual inspection. They walked the staircase  and catwalk on top of the condensation chamber torus but could not identy any location where leaks might exist. Basically all that was achieved was that the workers were exposed to 6.49 mSv (max) and that some shots of the brown transparent radioactive water in the basement were taken.

Admin's comment: The admin thinks it is hard to find the leaks by visual inspection. The leaks may be pretty small: 1 liter per second makes 84 m3 per day.

6/6/2012 - Safety systems for total loss of AC power discussed in Japan in 1993

The issue of additional safety systems to cope with total loss of AC power lasting more than 30 minutes was discussed by the Japanese authorities in 1993 but Tepco succeessfully managed to avoid the additional systems  by arguing "Sufficient safety can be guaranteed if appropriate management operations are implemented.” They  said: "It is not necessary to consider sustained, total losses of AC power, because it is possible to count on transmission lines being restored or on emergency AC power facilities being repaired." Now they know better, it took TEPCO more than 24 hours to install mobile equipment.

Admin's comment: The admin is convinced that there is a limit to improving the plant safety by installation of additional safety systems: Any additional improvement can only be achieved by accident management measures using technical means (mobile equipment). Therefore any additional effort should be directed towards providing mobile equipment and organisation and training of mobile equipment teams.

6/5/2012 - Solid waste to be buried on site

Tepco is planning to construct two burial places for solid waste on the Fukushima plant site. The objective is to get rid of contaminated debris and rubble. The plan is to contain this material in a surface contruction using a liner sheet and to put 1 m of soil on top to reduce radiation.

 

6/3/2012 - Thermocouple malfunctioning

Tepco reports on the malfunctioning of the temperature measurements. The report is in japanese.The malfunctioning of thermocouples in unit 2 poses a substantial problem. Out of 41 thermocouples 23 schow bad readings.

Tepco is working out a plan for thermocouple replacement which allows to minimize radiation exposure of replacement workers. The figure shows the situation in unit 2.

blue and green are consistent, red and black are malfunctioning.