Sunday, January 29, 2017

TEPCO Searches for Melted Fuel in Reactor 2, Encounters Very High Radiation Level But No Fuel, Yet



It is an unsolved mystery: Where is the missing reactor fuel from unit 2? Does it remain in the bottom of the reactor or has it melted into the basement or beyond? TEPCO is still trying to answer these questions:
Kohei Tomida and Takashi Sugimoto (January 27, 2017). TEPCO starts full survey inside Fukushima No. 2 reactor vessel. THE ASAHI SHIMBUN, http://www.asahi.com/ajw/articles/AJ201701270073.html

On Jan. 26, TEPCO inserted a camera-installed pipe into the containment vessel through a hole that had been made for the survey robot “Sasori” to pass through.

The radiation level around the hole was eight sieverts per hour, a deadly exposure level for humans. Workers were forced to perform their tasks while taking cover behind a wall, which was located about two meters from the hole….

…. To date, the utility has examined the inside of the containment vessel of the No. 2 reactor with an industrial endoscope three times. However, it has been unsuccessful in confirming the locations of the melted fuel.
Screenshots of reactor 2 (behind the large white vent stack)

Jan 29, 2017 4:15


January 30, 2017 1:55


The status of reactor 2 has remained somewhat mysterious throughout the Fukushima disaster. Here are some tidbits of information about this reactor I've collected:


REACTOR 2

On March 15, an explosion occurred in reactor unit 2. Western news coverage of ongoing events reported that the “containment structures of the three reactors—which house the all-important reactor vessels—remain intact, Japanese official stressed, preventing large-scale radiation leaks.”[i] Specific information about unit 2’s condition after the explosion was lacking.[ii]

At the end of March 2011, Japanese officials had reported they suspected only a “partial meltdown” had occurred in reactor 2,[iii] despite earlier March reports of concerns about loss of containment there.[iv] Later in 2012, Tepco reported that unit 2 had been the primary source of radiation releases.[v]

In February of 2015, TEPCO admitted that radioactive water from unit 2 had been flowing unfiltered into the ocean since May 2014.[vi]

Local fisherman who had given consent for TEPCO to dump uncontaminated ground water were outraged, but Yuji Moriyama, a TEPCO spokesman stated “the utility did not disclose the information because there is no evidence of environmental impact.” The water contained 29,400 Becquerels of radioactive cesium per liter and an additional 52,000 Becquerels of beta-emitting radionuclides, such as Strontium-90.

In January 27, 2015, TEPCO measured 31,000,000 Bq/m3 of Strontium-90 in boring well nearest unit 2, a level which was more than 10 percent more than reported in December of 2014.[vii] By February of 2015, TEPCO was reporting even higher levels of Strontium-90 in the same location, with the highest sample measured at 590,000,000 Bq/m3 of Strontium-90.[viii] The spiking strontium levels are consistent with the predictions of the German melt-through scenario.

REFERENCES

[i] Hayashi, 2011, A1.

[ii] Y. Hayashi and A. Morse (16 March 2011) “Setback in Reactor Fight,” The Wall Street Journal, A1.

[iii] A. Morse and M. Obe (29 March 2011) ‘At Plant, Toxic Pools Threaten to Spill’, The Wall Street Journal, A12.

[iv] Hayashi and Morse ‘Setback in Reactor Fight.’

[v] ‘TEPCO's Post-Mortem Shows No. 2 Reactor Main Source of Radiation’ (25 May 2012), The Asahi Shimbun, http://ajw.asahi.com/article/0311disaster/fukushima/AJ201205250053, date accessed 25 May 2012.

[vi] Fisheries ‘shocked’ at silence over water leak at wrecked Fukushima No. 1 plant,” Japan times (February 25, 2015) http://www.japantimes.co.jp/news/2015/02/25/national/tepco-admits-failed-disclose-cesium-tainted-water-leaks-since-april/#.VPOfiOHWyDl

[vii] Lori Mochizuki, “31,000,000 Bqm3 Strontium 90 Measured Nearest Boring Well Reactor 2,” Fukushima Diary (January 2015) http://fukushima-diary.com/2015/01/31000000-bqm3-strontium-90-measured-nearest-boring-well-reactor-2). TEPCO document available: http://www.tepco.co.jp/nu/fukushima-np/f1/smp/2015/images/2tb-east_15012701-j.pdf

[viii] Lori Mochizuki (Fukushima Diary 590,000,000 Bq/m3 of Strontium-90 measured from groundwater of Reactor 2 seaside). 

7 comments:

  1. I do not think the fuel dissembled into several pools. That is what they would have us think.

    ReplyDelete
  2. Fuel debris possibly found below No. 2 reactor at Fukushima nuclear plant: NHK
    http://www.japantimes.co.jp/news/2017/01/30/national/fuel-debris-possibly-found-no-2-reactor-fukushima-nuclear-plant-nhk/#.WI7iNvLraM9

    ReplyDelete
  3. TEPCO may have located melted fuel for 1st time at Fukushima plant
    http://www.asahi.com/ajw/articles/AJ201701300058.html

    ReplyDelete
  4. Melted fuel possibly found inside of crippled Fukushima reactor
    A survey on the inside of the No. 2 reactor at the tsunami-ravaged Fukushima No. 1 Nuclear Power Plant has shown a black object, which its operator says could be melted fuel, sources close to the case said.
    Experts at Tokyo Electric Power Co. (TEPCO), the operator of the crippled power station, are analyzing the object.
    TEPCO conducted the survey on the inside of the reactor by inserting a camera attached to the tip of a pole inside on Jan. 30.
    The survey shows the black object near a grating, which is used as a foothold for plant workers, just below the reactor's pressure vessel.
    Following the outcome of the survey, TEPCO plans to send a remotely controlled robot into the reactor building to get a closer look at conditions, beginning in February.
    At the time of the outbreak of the nuclear crisis, there were 548 fuel units inside the No. 2 reactor, according to company officials.
    http://mainichi.jp/english/articles/20170130/p2a/00m/0na/022000c

    ReplyDelete
  5. Possible fuel debris located in reactor
    NHK has learned operators of the crippled Fukushima Daiichi nuclear plant believe they may have located molten fuel inside one of the plant's reactors.
    If confirmed, this would be the first time since the 2011 nuclear disaster that they have managed to determine the exact location of the debris.
    The operator of the plant, Tokyo Electric Power Company, began sending a remote controlled camera into the containment vessel of the Number 2 reactor last week.
    On Monday, it transmitted images of a black mass on the floor under the reactor core.
    The operator suspects it is fuel debris, a mixture of molten fuel and broken interior parts.
    It plans to send in a robot equipped with a radiation-measuring device early next month to get a better idea.
    TEPCO plans to hold a news conference on Monday to explain more about the finding.
    https://www3.nhk.or.jp/nhkworld/en/news/20170130_23/

    ReplyDelete
  6. If it is anything like the elephant foot at chernobyl, it is almost unapproachable.

    ReplyDelete

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