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

Friday, April 1, 2011

Friday morning update: Fukushima Daiichi

The news coming out of Fukushima Daiichi, and Tokyo, vis a vis TEPCO's response to the accident isn't making TEPCO look very good at all. TEPCO is getting hammered, publicly, by NISA and a professor of nuclear engineering has appeared on Japanese TV giving a not necessarily positive view of the delays in establishing decay heat removal at the plants following the loss of battery power.

As to NISA's problems with TEPCO... NISA has told TEPCO to go back and review all its radiological data again since it keeps releasing data on contamination or activity in water, and then revising it. Then there's the dosimetry issue, discussed here previously. The total effect is that both TEPCO's operations people and their radcon (radiological controls) people are getting beaten up.

I'm not going to judge them, myself. They're struggling with fantastic adversity even now; perhaps their training was good before this, or perhaps it wasn't. Those weaknesses, if and when found, will be an integral part of the overall review of this accident after it's all over and will help determine prevention of future occurrences. In many nuclear accidents, people have been the problem... or else a very large part of it. But we must wait to see.

Meanwhile on the operational standpoint, the latest JAIF status document reflects no significant changes. We note that trench water level now appears as a data point under "major data" on the fifth page.


Efforts to move water out of the condensers and into other tanks continues. The US Navy barge with fresh water is docked nearby, but no word of any water transfer from it yet. With any luck we'll have further NISA and TEPCO data later on today to help determine the effect of core cooling and spent fuel pool cooling efforts.

6:00 AM Eastern Friday 4/1


  1. Will, thanks for this blog, very informative and putting things into perspective.
    I wonder about two issues:
    1) What do the activities of 26 - 42 Sv/h in the dry wells mean? (numbers from NISA 31.03. 06:00)
    2) NISA says that 150 L/min fresh water are pumped into the core via the fire extinguish line. This makes about 200 t / day. Where does all this water go?
    Is it evaporating and going into the generator/condenser? Or leaking into the containment and or suppression chamber?
    Would be great if you could shed some light on this.

  2. Considering that the high end of that range is 4200 Rem/hr I'd have to say it means that there are a large amount of fission product gases in the drywell. CAMS is an airborne contamination monitoring system, monitoring activity from airborne contaminants.. in other words, it's not monitoring a rad field produced by the reactor but by the airborne particles.

    No one is saying right now where all this water is going. They're injecting water -- meaning they're not recirculating it. Although you'd imagine they'd be routing it to the ideal place - the main condenser - it sure seems as if they're not, since these are being used to take the basement water. I have suspicions that it's either leaking out of the reactor vessel, or being let out through reliefs, or both. There are a number of flowpaths that can be established. We will know in a day or two as the water problem becomes more acute. If I were at the TEPCO press conferences I'd have asked this question over a week ago.

  3. Thanks Will,
    One follow-up question:
    Reactors 2 and 3 show low pressures in the RPV despite elevated nozzle and bottom head temperatures, in contrast to reactor 1 where pressure is high (as is the temperature). Does this - together with the CAMS data - imply that integrity of both RPV 2 and 3 is affected? To my knowledge this has only been said for RPV 2.

  4. At this point it's probably difficult to prove integrity of any of the sets of combined pressure vessels and unisolable primary piping at any of the plants. Various people keep assuring integrity of one or another of the pressure vessels, but really there will not be solid proof until we see them. Which might be a couple years down the road.