Plumes of Mysterious Steam Rise from Crippled Nuclear Reactor at Fukushima

RT
January 1, 2014

AFP Photo / TEPCO

Fresh plumes of most probably radioactive steam have been detected rising from the reactor 3 building at the crippled Fukushima nuclear plant, said the facility’s operator company.
The steam has been detected by surveillance cameras and appeared to be coming from the fifth floor of the mostly-destroyed building housing crippled reactor 3, according to Tokyo Electric Power Co (TEPCO), the plant’s operator.
The steam was first spotted on December 19 for a short period of time, then again on December 24, 25, 27, according to a report TEPCO published on its website.
The company, responsible for the cleanup of the worst nuclear disaster since Chernobyl, has not explained the source of the steam or the reason it is rising from the reactor building. High levels of radiation have complicated entry into the building and further inspection of the situation.
Three of the plant’s reactors suffered a nuclear meltdown in March 2011 after the Great East Japan Earthquake and resulting tsunami hit the region. The plant is comprised of six separate water boiling reactors. At the time of the earthquake, reactor number 4 had been de-fueled and reactors 5 and 6 were in cold shutdown for planned maintenance, thereby managing to avoid meltdowns.
Unlike the other five reactors, reactor 3 ran on mixed core containing both uranium fuel and mixed uranium and plutonium oxide, or MOX nuclear fuel. The Reactor 3 fuel storage pond still houses an estimated 89 tons of the plutonium-based MOX nuclear fuel composed of 514 fuel rods.
In a similar incident, small amounts of steam escaped from the reactor 3 building in July 2013, Asahi Shimbun reported. However it was unclear where the steam came from. TEPCO said that radiation levels did not change, adding that the steam could have been caused by rain that found its way to the primary containment of the reactor, and because this vessel was still hot, the water evaporated. On 23 July the steam was seen again coming out of the fifth floor just above the reactor containment, the Japanese newspaper reported.
In November, TEPCO, responsible for the decommissioning of the plant, began the highly risky removal of over 1,500 potentially damaged nuclear fuel rods from reactor 4. The reactor is the most unstable part of the plant as it was offline at the time of the 2011 catastrophe and its core didn’t go into meltdown. Instead, hydrogen explosions blew the roof off the building and severely damaged the structure.One of the most dangerous operations attempted in nuclear history was a success as a total of 22 assemblies containing 50 to 70 fuel rods have been transported to a new storage pool. While the extraction of the fuel rods is a significant challenge for TEPCO, a more complex task of removing the cores of the stricken reactors is yet to come.

This article was posted: Wednesday, January 1, 2014 at 2:59 pm

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Mystery Steam Over Fukushima Could Be Sign of Another Meltdown

gizmodo.com

12/31/2013

 

The newest update in the highly disconcerting series of devastating failures that is the Fukushima cleanup effort is troubling to say the least. Tepco has confirmed that (unexplained) plumes of steam have been rising from the mangled remains of Reactor Building 3. In other words, there's a chance Fukushima could be in the middle of another meltdown.

The thing is, no one has been able to find out the exact cause of the rising, mysterious radioactive steam because the combination of physical damage and, more importantly, lethal radiation levels have made investigating the reactor impossible. Tepco has known that a followup meltdown was a severe possibility, though. The Reactor 3 fuel storage pond is still home to about 89 tons of plutonium-based mixed-oxide fuel according to the The Ecologist, and should that fuel storage pond dry out, the highly radioactive rods will melt down with devastating results.

Still, there are two other slightly less severe possibilities outlined by The Ecologist. First, the molten fuel could have burnt its way through the base and into the soil below, producing steam as it comes into contact with groundwater (while simultaneously releasing radioactive contaminants into the ocean). Second, reactor rod fragments could have come into contact with rainwater, producing extreme amounts of heat and, consequently, steam. As The Ecologist notes, "Of the three choices this is probably the least serious."

While some of the possible outcomes might be better than others, nothing we're facing is exactly ideal. But of course, that seems to be the recurring theme for Tepco's efforts at containing the Fukushima disaster. Why change now. [Tepco via The Ecologist via Fark]

Original article:  http://gizmodo.com/radioactive-mystery-steam-over-fukushima-could-mean-ano-1492280971