Fukushima Daiichi update: Tuesday June 14, 2011

Developments of note at Fukushima Daiichi over the last two days...

TEPCO has begun operations with the previously mentioned system to remove contaminants from the seawater which is inside the breakwalls, and silt fences, in order to help prevent spread to the outer waters.

TEPCO has also begun intermittent operation of the first system set up to decontaminate water in the various onsite buildings. Various parts of this system, pictured previously on this site, are being tested separately and then in conjunction, first using plain water and then using low-level contaminated water. TEPCO's plan indicates that the whole system is to be in operation decontaminating water by the 18th of June, if all goes as planned. This system, contracted to Kurion, is only the first; the larger and more capable system contracted to AREVA has not yet begun construction.

Contaminated water is being pumped from No. 3 reactor building to the rad waste storage facility as this is written. This is part of the ongoing general move to get access to the turbine buildings at all three affected plants in order to restore cooling.

Water injection to the reactor cores at all three affected plants continues essentially as before, using the feed lines and at roughly the same rates. However, temperature on the No. 3 plant, which had been rising steadily, has now begun to decrease again with the most recent pressure vessel lower head temperature reading we have being about 161C which is ten degrees or so lower than when we last updated on this site. Water injection at this plant is actually down very slightly to 11.2 cubic meters per hour at last measurement.

In the interest of completeness, as we've detailed before, work continues at No. 2 and No. 3 plants to gain access to the reactor buildings to install new water level and pressure gauges, and to allow for nitrogen injection to the dry wells. To this end the atmospheric work at No. 2 continues, while just recently TEPCO used a concrete pump truck to extend a sampling probe over the No. 3 plant's reactor building. TEPCO press photo of this operation is below.



According to TEPCO, today a remote helicopter was used to conduct further detailed surveys around the No. 1 reactor building as serious preparation work is now underway to construct the temporary contamination shield cover for this building. This is the first of two different types of enclosures that will eventually cover all of the reactor buildings on site; first, this temporary style and later a much sturdier and heavier type which will be that which encloses the buildings while the reactors are opened and defueled.

The preparation for installation of these first style enclosures is fairly elaborate. In addition to surveys on the ground, TEPCO has, as mentioned, used air surveys and laser imaging to obtain exact dimensions. Here are two images showing steps in the laser imaging and dimensioning process, from TEPCO press releases. Both show No. 1 reactor building.

Above is an external view of the reactor building of No. 1 plant as it is now, and below is an image with the new enclosure added. Click both to enlarge.


Below is a VERY large image (when clicked) of the reactor building enclosure, which is exceedingly well detailed and worth close examination.


Below is a scale model TEPCO and its contractors have developed of the reactor building first style enclosure. Again, courtesy TEPCO.


And finally we have a TEPCO press photo of an actual reactor building enclosure being test assembled at Onahama port, in practice for installation at the Fukushima Daiichi site.


Shortly at the Atomic Power Review YouTube Channel we will have some TEPCO press release videos showing the survey and construction process for the erection of these first-style reactor building enclosures. Click here to see the APR YouTube Channel.

9:40 PM Eastern Tuesday 6/14
ATOMIC POWER REVIEW

UPDATE: Just added this morning is a new TEPCO video showing the radiation survey work inside No. 3 reactor building on June 9th. Look at the APR YouTube channel now to see it. Link above, and always in red on the right of APR's page.

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Fukushima Daiichi update: Saturday, June 11, 2011

It has been three months since the Great East Japan Earthquake today. Also, then, as a result three months since the initiation of the Fukushima Daiichi Accident by the tsunami which resulted from the earthquake and which inundated the site. The tsunami then caused what in many quarters is recognized now as the classic long-term SBO event but extended to a point not previously imagined without either AC or DC power on site, and with further equipment derangement than generally imagined due to the tsunami waters which overran what had been assumed to be worst-case-preventive defenses. Accident recovery has been hampered by the hydrogen explosions in the reactor buildings, which from the explosion in No. 1 building led to many further site complications due to debris from one plant interfering with actions at other plants, thus causing a complicated interrelation of cause and effect sequence and decision making not perceived as probable in design basis accident analysis. While many of the events on site have actually been exactly predicted -- even down to roughly the hour or two hour event times -- by previous accident analysis studies (mostly under the auspices of Oak Ridge National Laboratory) many of the complicating factors were not. Just as TMI-2 led to a re-evaluation of how many seemingly unrelated existing flaws both in personnel and equipment can lead to an accident that essentially fills a DBA scenario without being a classic DBA event, so now does Fukushima Daiichi cause the nuclear industry to widen its scope particularly and thoroughly on multi-reactor nuclear generating sites where the reactor plants are closely spaced, or worse, immediately adjacent. This is not by any means the sole area to be studied, but it fairly jumps out at the investigator at even the most cursory examination. With that, here are the most recent details from Fukushima Daiichi.

TEPCO is now testing its large water purification facility, assembled over the last week or so. TEPCO still intends to have this equipment functioning within the next week.

Water injection rates to the reactor plants remain unchanged. Temperatures at No. 1 and No. 2 plants are stable, but No. 3 continues to drift upward, with bottom vessel head temp at last report being 189.2C (372.6 F).

Today, in the effort to gain working access to all reactor buildings for restoration of pressure and water level detection, and restoration of spent fuel pool systems, TEPCO finally opened up the double air lock doors at No. 2 plant and began working on filtering the air. In No. 3 plant, gamma camera surveys were conducted to map out the areas of high radiation in preparation for the aforementioned events and for the preparations for nitrogen injection to the primary containment. Areas of up to 10R/hr were found in No. 3 plant's reactor building. Nitrogen injection to No. 1 plant still continues, only rarely interrupted due to outage or nitrogen generator problems so that at the moment TEPCO estimates that over 43,000 cubic meters of nitrogen gas have been injected to the dry well for the purpose of inertion (against hydrogen gas combustion / explosion.)

Personnel have entered No. 4 plant as noted earlier to support the spent fuel pool, and some new TEPCO press photos are now available. These were taken on June 9th and 10th. First, the fourth floor view:


Next, water treatment equipment in No. 4 reactor building.


The damage seen above is considered by TEPCO to be serious enough to hinder its attempts to restore the original spent fuel pool systems for the purpose of cooling the spent fuel pool. Not only is there debris everywhere, but there is also piping damage that TEPCO apparently had expected not to find.

TEPCO continues to bring in water storage capacity as rapidly as possible. The large tanks mentioned on this site a short while back are now arriving on site and are being mounted and connected. First of our two TEPCO press photo displays is one of the tanks during the night-time shipping routine, chosen to avoid obstruction of roads and thus daytime traffic.


Below, the installation of the tanks at the Fukushima Daiichi site.


These are the most important confirmed details at the moment. More to come.

10:25 PM Eastern Saturday 6/11
ATOMIC POWER REVIEW

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Fukushima Daiichi: Wednesday update June 8

First.. there are reports circulating in the press, seemingly particularly on anti-nuclear sites and anti-nuclear leaning big media that the Japanese are submitting a report to the IAEA that "admits" total core melt and some core material exit from the reactor pressure vessels at all three affected reactor plants.

This has been reported on this blog for months. It is not new; it is not news.

This blog may have been the first to begin quoting ORNL SBO scenario analysis indicating core material falling below the core support plate and damaging, first, lower vessel head penetrations ... which reports seemed likely to match up well with the events known at that time to have occurred and to be occurring at Fukushima Daiichi. It was probably also the first to speculate on the possible failure of the support plate and quenching of the core material in water still contained in the bottom plenum, among other things, a long while back. Readers of this blog were already aware of these kinds of possibilities and events and, upon reading this report, would find nothing new or surprising in it. This gives our readers both pro-nuclear and anti-nuclear a definite leg up.

Now, briefly, there has also been an oil spill reported at Fukushima Daini. Repeat-- this is the other plant, further south, with four reactors. This oil spill is under control and is minor.

Getting back to Fukushima Daiichi; below are the promised photos of the initial setup TEPCO will use to decontaminate water on site as early as next week if all goes well. We will show the components of this system in order. All photos courtesy TEPCO (Tokyo Electric Power Company.)

First, the oil separation tank.


Next, two views of the cesium absorption towers:



Next, decontamination equipment (TEPCO indicates this to be nuclide coprecipitation and absorption equipment):



The next .. and last .. steps shown are desalination and water treatment, although there is planned to be one further desalination and treatment step beyond this which is not yet built.




TEPCO has begun installation of 32 steel support beams below the spent fuel pool in No. 4 plant at Fukushima Daiichi. More TEPCO press releases show the location of this work, the beams as received at the plant, and two of them actually installed helping support the spent fuel pool itself.




3:35 PM Eastern Wednesday June 8, 2011
ATOMIC POWER REVIEW

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Fukushima Daiichi update: Tuesday June 7

A number of developments have occurred since our last report.

NISA has completed a first review of data demanded from TEPCO relative to plant indications and personnel actions in the early days of the accident and according to press reports has concluded that serious core damage began to occur at the Fukushima Daiichi site's No. 1 reactor only several hours after the tsunami. Specifically, the reporting indicates that fuel exposure (to a steam only environment I assume) began two hours after the tsunami and core melt began a total of five hours after the tsunami. Damage to the other two reactor cores (No. 2, No. 3 plants) did not begin until 79-80 hours after the tsunami. The estimate of the very early damage by NISA is in line with statements that, for whatever reason, the isolation cooling system was shut down very early into the accident; these statements were made by TEPCO within the last month.

Further indication of the serious damage at No. 1 plant is the fact that TEPCO's new, temporarily installed pressure gauge at No. 1 plant is reading essentially atmospheric pressure or slightly above. This means that -- IF the gauge is correct -- the reactor vessel is in much better communication with the outside environment than might previously have been assumed.

As continuously noted, TEPCO continues to struggle with the water exiting the reactor cores and at last total had what it felt was over 105,000 tons of contaminated water on site (contaminated to various degrees, and in total.)

In other reports, NISA has calculated that the core melt events at the three reactors likely produced from 800 to 1000 kilograms of hydrogen at each of the plants. As we've detailed here many times, this hydrogen came from both the metal-water reaction of the zirconium-alloy ("zircaloy" is the trade name) fuel rod clad and from some radiolytic dissociation of water. This is the hydrogen that exploded and caused the damage of the reactor buildings. For comparison purposes, if we convert to standard measure and find that the Fukushima plants developed from 1760 to 2200 pounds of hydrogen each and compare with the something over 700 pounds developed at Three Mile Island 2, it becomes obvious why the reactor buildings were so severely damaged at Fukushima. At TMI, the hydrogen burn caused a pressure pulse (of about 28 psig if I recall) but did no permanent damage; the hydrogen burn was contained entirely inside the reactor containment (which is of an entirely different and probably superior design.) The damage to No. 1 and No. 3 buildings is obvious; damage to No. 4 building was due to hydrogen leaking INTO that building from No. 3 plant's common vent. The hydrogen explosion at No. 2 plant was more contained but damaged the suppression pool or "toroid" below the plant.

Water injection to the reactor cores continues as noted in previous posts. Injection to spent fuel pools continues occasionally, with hydrazine added as TEPCO deems necessary (this is a corrosion inhibitor.) Temperature of No. 3 reactor is climbing slowly, and has been since May 28th.

TEPCO hopes to have its first water decontamination plant operating on or about June 15th at the site. (Pictures of this plant will be up on this site later today.)

As a result of the video of steam release in the No. 1 reactor building many people have commented or e-mailed asking just where this steam was spotted by the robot. The TEPCO map below shows clearly the location of the pipe penetration in the floor.

The date of the above illustration is June 4.

As noted previously TEPCO continues to bring a great deal of tank capacity on site, in order to get a leg up on the buildup of water from core injection; this has been occurring over roadways to the site since June 4, according to TEPCO press releases.

More details later.

7:45 AM Eastern Tuesday June 7, 2011
ATOMIC POWER REVIEW

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TEPCO Video: Dust inhibitor operations

New TEPCO release depicts dust inhibitor spraying operations at No. 2 plant, Fukushima Daiichi site.

DUST INHIBITOR OPS

As with previous links of this nature this video is hosted on the new Atomic Power Review YouTube channel, started up May 17th of last month.

5:50 AM Eastern Sunday June 5, 2011
ATOMIC POWER REVIEW

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TEPCO video: Steam and high rad levels in No. 1 plant

Tokyo Electric Power Company has released a video, taken June 3 by a robot during a survey inside No. 1 reactor building, showing steam rising around pipe penetrations. Video below courtesy TEPCO.

TEPCO VIDEO; STEAM IN NO. 1 REACTOR BUILDING

According to reports there are local radiation levels between 300 R/Hr and 400 R/Hr in the approximate vicinity of the video shown here.

TEPCO also released more photos from inside No. 1 plant, showing the new temporary pressure gauges installed to indicate pressure in the reactor vessel, and some workers in the area of the new gauges. Two pics below courtesy TEPCO.



5:50 AM Eastern Saturday June 4, 2011
ATOMIC POWER REVIEW

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Fukushima Daiichi update: Friday June 3

TEPCO is rapidly running out of room for contaminated water, due partly to water injection and partly to rain at the site. The company has announced that beginning tomorrow it will begin shipping two sizes of tanks (100 and 120 cubic meters in volume) from Tamada Kogyo Corporation's plant in Tochigi Prefecture to the Fukushima Daiichi site for installation. These will supplement all the other tanks being installed on site, and the "mega float" now firmly secured to the pier at the site. The company expects most of the shipments to be performed at night, and expects about six of the large units per day to be shipped from now until early July, and four units per day of the smaller size from the middle of June through the middle of August. This will vastly increase the capacity for contaminated and then later for cleaned-up water on site. NHK is carrying the line that TEPCO has reported having as much as 105,000 tons of contaminated water on site right now, in all of the various affected and damaged buildings, and tunnels and installed tanks as well as the rad waste building. Filtration equipment may be on line as early as June 15.

Below, some of the temporary tanks installed near Units 5 and 6 in a TEPCO release.


And some further... and much larger (click to expand) TEPCO press photos showing the interlinked tank setups. Note that these are NOT the same as the tanks mentioned in the opening paragraph of this post. These are the previously designed tanks for temporary storage, and the tanks now ordered will vastly exceed these in total capacity later on when fully installed.






Water injection (all feed line injection) to No. 1 and No. 2 plants stands at about 5 cubic meters per hour, both, and both have feed nozzle temperatures right at about 110C. No. 3 plant's injection rate is 11.5 cubic meters per hour with a feed nozzle temperature of 150C.

TEPCO, no longer believing the previous reactor vessel pressure indication, has installed a temporary gauge at No. 1 plant which will be viewed remotely by a temporary television camera. TEPCO has noted for some time, apparently, that feed pump discharge pressure was widely disparate from the indicated instrument pressure and has made this move to correctly determine the value. TEPCO's press release (handout) indicates this work will also be performed identically at the other two reactors affected.

There is a small flap going on among various entities in Japan over cylinder liner failures in some EDG's. One at the fast breeder Monju plant has been found with failed liners, and investigation has shown that liners of certain original vintage (made Feb '87 through May '89) may have excessive lead content and thus be weak... although a note was made about jacking the liners without adequate monitoring leading to excessive forcing. As far as TEPCO is concerned, only Fukushima Daini No. 2 and No. 4 plants have similar diesels with similar liners, so that the problem appears not to be wide spread.

9:00 PM Eastern Friday June 3, 2011
ATOMIC POWER REVIEW

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