containmentvesselvia EX-SKF / January 19, 2014 / This is today’s update on the water leak from the MSIV (Main Steam Isolation Valve) Room of Reactor 3 at Fukushima I Nuclear Power Plant. (Previous posts on the subject are here and here.)

TEPCO says they did the nuclide analysis of the water sample that the robot collected. The temperature and the levels of contamination indicate it is the water that comes out of the Pressure Vessel/Containment Vessel.

TEPCO’s way of saying it is that “the water is not the one that goes into the reactor.”

However, the levels of contamination of this water is one to two orders of magnitude smaller than the highly contaminated water in the reactor building basements, which seems to me to indicate that this leaking water is diverted out of the Pressure Vessel it comes in full contact with the corium (wherever it is – part at the bottom of the PV, part buried into the concrete floor of the Containment Vessel).

Nuclide analysis of the leaked water: sample taken on 1/19/2014

  • Cesium-134: 7.0×10^2 Bq/cm3 (700 Bq/cm3)
  • Cesium-137: 1.7×10^3 Bq/cm3 (1,700 Bq/cm3)
  • Cobalt-60: 2.5×10^1 Bq/cm3 (25 Bq/cm3)
  • All-beta: 2.4×10^4 Bq/cm3 (24,000 Bq/cm3)

Temperature of the leaked water: measured at 5PM on 1/19/2014

  • About 20 degrees Celsius

*Atmospheric temperature at the location of the leak: 7 degrees Celsius (measured at 10AM, 1/19/2014)
Temperature of the water being injected: 7 degrees Celsius (measured at 5PM, 1/19/2014)

Latest nuclide analysis of water being injected into reactors: sample taken on 12/10/2013

  • Cesium-134: below detection level
  • Cesium-137: below detection level
  • Cobalt-60: below detection level
  • All-beta: 2.8 Bq/cm3

The leaked water is higher in density of radioactive materials than the water being injected into the reactors. The temperature of the water is also higher. Therefore we believe this is not the leak of water that is being injected into the reactor. We will continue to investigate the cause of the leak.

TEPCO’s alert has a link to the latest nuclide analysis of water samples taken at different stages of contaminated water treatment (published on 1/17/2014).

According to that analysis, the highly contaminated water that sits in the reactor building basement (supposedly after having come to full contact with the corium) has:

  • Cesium-134: 1.0×10^4 Bq/cm3 (10,000 Bq/cm3)
  • Cesium-137: 2.5×10^4 Bq/cm3 (25,000 Bq/cm3)
  • Cobalt-60: 1.4 Bq/cm3 (after treatment with SARRY)
  • All-beta: 2.3×10^4 Bq/cm3 (23,000 Bq/cm3, before RO treatment)

While the Japanese media continues to not see much significance of this leak, the workers who have been tweeting from Fukushima I NPP from the beginning of the accident seem to worry. The issue here is NOT whether this water is currently leaking into the surrounding environment. The issue is whether the MSIV and/or its ancillary systems failed in the March 2011 accident.


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By Broc West| 2 Comments | Featured, News


  1. The above article misquotes the Tepco Press Release. Here’s what the statement actually says, “The water is assumed to be flowing out from the Primary Containment Vessel and it is confirmed to be flowing to the basement of the Reactor Building where accumulated water exists and not flowing out of the building. No significant changes in the monitoring results at the power station are confirmed and the reactor is steadily cooled.”

  2. If it came out of the pressure vessel it has already been in full contact with the corium. All of which as far as is known is still inside the pressure vessel. There is no definite indication that any corium is in the containment vessel in the concrete. as the water flows down to the bottom of the containment vessel it cools and the radioactive materials settle out onto the floor of the basement , increasing the amount of radioactive materials in there. As some off the water evaporates the remaining water will naturally become more radioactive than that coming directly out of the pressure vessel, since that water is constantly being circulated and cleaned, but not that in the basement. You can’t use this as an indication that there is corium anywhere else but in the presure vessel.

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