APR: your source for nuclear news and analysis since April 16, 2010

Thursday, March 17, 2011

Latest on spent fuel pool cooling attempts, Daiichi

As noted earlier, the helicopter drops focused on No. 3 plant only. Experts are saying that the effort appeared fairly ineffective; THIS writer agrees. Only the first shot (I watched all of it live) seemed a direct hit.

There was a very brief mention during one press conference, not repeated anywhere since (but I caught it) that there was a spike in suppression chamber pressure at the time of the drops. The implications of this are numerous but also might simply have been the direct impact of over seven tons of water on the structure and area with that first (lowest, most direct) water drop. Pressure may not have spiked; the detector may have been jarred, in other words. All speculative.

The water cannon vehicles have not yet entered the site so far as can be determined.

6:20 AM Eastern Thursday 3/17


  1. Regards, I came to your blog looking for Atom feeds of JAIF status chart updates, but I think I am staying :)

    I am an engineer but not a nuclear one. If it is not instrumentation error and pressure in the suppression chamber really spiked, what are those numerous implications?

  2. According to Kyodo they have just begin spraying water from fire trucks.

  3. Ground level perimeter radiation levels are reported to be dropping.

  4. Great blog you've got and I appreciate it very much. By the way, where did you see this live? Any site I could watch stuff like this?


  5. TEPCO's news release said that at 6:15 on the 17th they saw an increase in pressure in the suppression chamber on 3. But that was before the initial water drops.

  6. The worst implication I can think of if the pressure spike was directly related to the first direct hit water drop is that the containment is compromised and that the impact of water either got down to the suppression pool itself.. or else both primary and containment are compromised and steam was generated when the water entered the primary. HIGHLY speculative, but I think now we might see gradation of damage to various systems we had not expected... while others appear to have survived well beyond expected limits.

  7. @ mencial, I can speculate on one of the implications. First off,let me say that I heve actually been inside a GE mark I primary containment, up near the top of the reactor vessel head. It's a pretty small annular space. There is a bulkhead at the top of the sealing the top of the reactor separating the drywell from the reactor headspace. This is for flooding the headspace during refueling operations. There are hatches in this bulkhead that are opened during normal operation to allow air cooling of this headspace from the rest of the drywell space via the dry well coolers. Any how the water ran down around the shield blocks and onto the drywell head. If the drywell head gaskets were blown, the water would run in from the refueling pit into the drywell and onto the hot reactor head and through the cooling hatches to the rest of the drywell and the steam flash caused the pressure spike in the primary containment(drywell). Wow! that took a lot longer to explain and type than it did to picture in my head. Any how I hope this helps.
    And there does appear to be steam rising from this area of the wreckage.

  8. Thanks for the inside view, Greg! That's exactly the kind of exact particulars we're not able to get right now because no one can get in there! Your look inside is as good as being there.