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Wednesday, August 17, 2011

Nuclear Energy in Japan: August 17, 2011

We have a number of situational updates today concerning both the overall nuclear energy situation, such as it is, in Japan and the operations at Fukushima Daiichi.

Perhaps most interesting is the report by Kyodo that the No. 3 plant at Tomari Station in Hokkaido is operating at 100% rated power generating electricity - but has not officially been returned to service. Under the complicated Japanese system, this reactor has been undergoing its final post-inspection operational evaluation for months - as reported on this site at least twice - but has not been given the approval by the prefectural government for commercial operation. As we understand it now, the plant is operating at full rated load supplying power to the grid, but for accounting purposes is not being assessed as providing power - it's essentially free while the plant is in post-inspection evaluation, but pre-commercial operation approval status. This equates to limbo, and there is no reason why this plant (and many others) should not be returned to service immediately, commercially. The governor of Hokkaido wants the prefectural government body to immediately approve the commercial operation of the plant.

Perhaps not surprisingly, given the continuing tendency of government bodies in Japan not to allow restarts of reactor plants (and now this is worse with the IAEA stress test regime) we see reports that the costs of fossil fuels for the various utility companies in Japan have risen anywhere between 28% and 50% as compared to the same time last year, as reported by NHK. One can only hope that the stress tests are completed extremely rapidly and that the idled nuclear plants which are found safe (and that, frankly, will be most or all of them, we suspect) will be started back up. The last thing Japan's economy needs now is a major spike in fuel costs.. which has already started, as reported.


We are now beginning to get exact details about events which occurred during what we might term as the inception phase of the accident at Fukushima Daiichi. NHK has reported today that the shutdown of the cooling system at No. 1 plant was manually performed by a worker who did not receive orders to do so, and who shut down the system (Isolation Condenser) because it "appeared to be boiling." This is exactly the kind of human error we saw at Three Mile Island, when an operator shut off cavitating reactor coolant pumps to protect the pumps. In both cases, operation of equipment was required to protect the core, with the condition of the equipment being used to do this considered secondary. For example, in the situation at TMI (which I will not fully detail here) once a cavitating pump fails, it would be shut off and another started to get water flow through the core. In the case of Fukushima Daiichi No. 1 plant, the IC system should have been kept operating and any consideration to stop it should have come from the plant management - who says that they were not aware that the system was secured this early, and did not give any such order to do so.

It cannot be overemphasized that reactor plant casualty operation must always focus on the condition and safety of the reactor core. At no time should any consideration about other equipment supersede a consideration about reactor safety. In the case of Fukushima Daiichi, it was plainly obvious to everyone within fifty miles that a massive tsunami had come on shore and it was plainly obvious to everyone at the plant that the situation would be grave from the outset. It is this kind of consideration that requires the immediate judgement to NOT shut down such a system, given the fact that no electrical power was likely to be available at all soon.

Now, before I begin to make TEPCO look completely incompetent (and they are not,) I would like to add that another report today states that TEPCO's people did not consider any possibility of hydrogen explosions at the plants with massive external effects such as occurred at Fukushima Daiichi. Surprisingly, NHK has said that the failure to expect an explosion external to a containment vessel "exposes the utility's underestimation of the potential dangers at the plant." This goes just a bit too far; according to present testimony, TEPCO was very concerned about the condition of the cores and primary containments (dry well, suppression chamber) and never expected an explosion of hydrogen gas outside of this (not that they expected one INSIDE, either) because the plant design is supposed to prevent this by the design of vents. Unfortunately, it does appear that the venting system at No. 1 plant was an add-on later on to the plant's normally installed offgas system and was not effective. TEPCO believed, then, what everyone else believed pre-Fukushima, which is that any chance of a hydrogen explosion was INSIDE the containment, normally inerted, and was naturally prevented by either this inert atmosphere or by venting of the containment. It is possible to be too critical of the owner-operator; the truth about TEPCO's real operational ability will be somewhere between the extremes being reported frequently these days.

Once TEPCO experienced the explosion at No. 1 plant, it did try (according to NHK and other sources) to rush to prevent such occurrences at the other plants but the radiation and environment prevented this from being possible; this led to another externalized hydrogen explosion at No. 3 plant - and it does appear that hydrogen from this plant leaked through common piping into No. 4 plant causing the explosion there (which was much less powerful.) The "blast" reported inside the dry well or suppression chamber at No. 2 plant is presently assumed to have been an internal hydrogen burn, although there is still the chance (reported at that time on this blog) that it was a steam quench of part of the failed core, or even possibly a partial melt-out. Only direct inspection will tell in this case.

Taking all of this into consideration, we are finding EXACTLY the same kind of things we saw from Three Mile Island - which is, that a very convoluted combination of personnel errors and equipment problems (both design problems and failures due to the tsunami) led to the accidents at the plants. We are finding - as mentioned here very early, and now echoed by NEI, the NRC and others - that multiple accidents at the same site CAN be exacerbated by one initial accident, and that interference between plants is easily possible in accident scenarios, and that plant interrelations can occur even through something as seemingly unimportant as common vent piping. Just exactly as I've indicated here before, there will be many volumes of "lessons learned" from this accident - even if they tell us nothing we didn't already either know or suspect.

Getting to operational details at present on-site... TEPCO is testing a separate, supplementary and entirely Japanese-made decontamination system at the site to supplement or replace the existing failure-prone system. Results of the test will be made public.

TEPCO will begin operations soon to directly process the atmosphere inside the dry wells at the three plants with installed reactor cores, in order to filter out radionuclides that are still being vented to atmosphere. In addition to this, TEPCO will also begin using truck-mounted equipment to remove salt from the water in the spent fuel pools on site.

There are more tecnical details which we will report shortly in another post.

11:45 AM Eastern Wednesday August 17, 2011



  1. "Getting to operational details at present on-site... TEPCO is testing a separate, supplementary and entirely Japanese-made decontamination system at the site to supplement or replace the existing failure-prone system. Results of the test will be made public. "

    I assume you're talking about the water decontamination systems, as opposed to...perhaps an air filtration system?

  2. Yes, and there are a lot more details emerging.

  3. Some original reporting on worker reports of the state of the cooling pipe system after the earthquake: