Tuesday, April 12, 2011

#Fukushima I Nuke Plant: Reactor 2's RPV Temperature Is High

Something strange seems to be going on inside the Reactor Pressure Vessel of the Reactor 2 at Fukushima I Nuclear Power Plant.

Temperatures of the Reactor Pressure Vessels are measured at two locations: at the water nozzles (that TEPCO calls "A"), and at the bottom of the Vessels (that TEPCO calls "B"). The Reactor 2's "B" temperature was not recorded since March 31, but it suddenly came back on April 12, and the temperature is high, almost as high as the "A" temperature of the Reactor 1 RPV.

Now, the Reactor 2's RPV temperatures are:
A: 165.8 degrees Celsius
B: 208.1 degrees Celsius (it was 87.8 degrees Celsius on March 31)

In comparison, the Reactor 1's RPV temperatures are:
A: 216.2 degrees Celsius
B: 119 degrees Celsius


netudiant said...

Please keep in mind that these reactors are stuffed with hundreds of cubic feet of hardened salt left over from the period TEPCO was desperately cooling the site with salt water.
The estimate was about 50,000 pounds of salt precipitated out in each reactor, clogging cooling channels and impeding circulation. So there may well be very unusual temperature profiles in the reactors, especially if some of the fuel sits in a pile on the reactor floor, possibly protected from the cooling water by a crust of salt.

Anonymous said...

It may not just be salt, apparently there is also a lot of ocean sediment stirred up by the Tsunami in the seawater they used to cool the various fuel clusters. Normally BWR's operate on ultra pure water that is constantly treated to remove impurities. This "mud" might be working in conjunction with the salt to make an impervious layer of material that is interfering with heat dissipation.

"Another problem is that the water contains so much mud after the tsunami that it will be difficult to use it for cooling Fukushima Daiichi, said Beate Kallenbach-Herbert, a nuclear expert with the Oeko-Institut in Freiburg".


They've also had a few earthquakes in recent days that could have reconfigured the fuel debris in a manner that increased the temp in the lower portion of the vessel. Whatever the cause it is quite disturbing that the temp is still so variable and high after a month of ineffectual improvised cooling methods.

M. Simon said...

And recriticality is not out of the question. Depending on where the thermocouples are located.

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