Theory of corrosion and backflow through feedwater lines to explain Fukushima radiactive water leaks

Barry Brook tweeted the link to this article, which was originated by anonymous poster KBMAN on daily Kos. I’ve done a bit of quick surveying of KBMAN’s credentials and other writing on nuclear topics. My judgement is the writer is not a crank, he looks to know his subject. In the preamble to the captioned post, he wrote the following paragraph (encouraging to me as to intellectual integrity):

I also make every effort to be clear when I’m writing about known fact versus theory, interpretation, and speculation. In those cases in which I speculate on possible causes of current conditions or what future events might be I provide the supporting evidence which causes me to arrive at these conclusions. I’m also not attached to being right. If you have a perspective that I have not considered please mention it in the comments and we can discuss the relative merits of how we see things. I have very few things that I believe beyond doubt, and even those I have my doubts about 🙂 Seriously. What’s so trumps theory, belief, interpretation, speculation, etc. When presented with reliable evidence that contradicts what I have held to be so, I change my beliefs.

As the first comment to the NextBigFuture post, KBMAN offered a capsule of his credentials:

By way of qualifications, my training is in physics in which I have a bachelor’s degree. I also worked for five years at Oyster Creek Nuclear Generating Station in New Jersey. Like the Fukushima plants, Oyster Creek is a GE BWR-I with a Mark I containment. It has a power rating roughly 1/3 higher than Fukushima Daiichi 1. I worked on a number of projects while there including managing the computer system used by the core engineering group to manage the reactor core and fuel usage. I also took courses in both generic nuclear power operations and also the specific operations and systems at Oyster Creek. And relative to this specific diary, I developed software used by the plant to perform required federal testing of the integrity of the primary containment structure. In the process I learned a great deal about the Mark I containment, the basis for its design and the pressures it was designed to hold. I was also a member of the plant’s emergency response team and would have been one of those responding to an incident such as this.

In earlier posts KBMAN made it clear that he was not currently employed in nuclear, that his direct experience terminated 25 years ago. That said, he has a colleague from the Oyster Creek experience who was one Oyster Creek’s core engineers. He is passing difficult technical questions to this person for comment.

To the substance of his analysis, if KBMAN is correct, then my estimation of the likely Fukushima Daiichi scenario was wrong. Keeping in mind my limited knowledge of the BWR-I internals, I don’t see what is wrong with his analysis. So I encourage the reader to review his entire Kos post Fukushima Status Update 3/27 (Reactor water is in the ocean), his/her other Kos postings etc. Form your own conclusions. If you want a one-excerpt summary:

Likely-case scenario

Given the difficulties of the working environment and the problems with the leaking water I think it is optimistic to think they will have core cooling systems returned to service within the next week at any of the units. This will mean more feed and bleed to remove heat. Also, they will need to track down the exact pathway(s) water is taking to get to the turbine building and ocean. They may or may not be able to isolate the problem and stop the leaking. Next best would be to be able to contain the leak at its source and drain that container continuously. Obviously this doesn’t work if there are heat exchanger leaks but it may be possible to isolate this system using locally controlled manual cutoff valves.

I’m really not sure what is likely to happen with the leaking fuel pools. I fear that concrete entombment is likely in the future for at least one of them, possibly both units 3 and 4.
I expect the releases will need to continue for the next week at least, likely more until they get alternate means of heat removal back online. I also fear the ocean releases will continue for that same period of time, perhaps longer depending on the condition of the heat exchangers.

Cleanup and decommissioning may not be done as thoroughly as possible due to dose rates all around the site. They may well end up covering everything with sand, gravel, or other more suitable materials to contain the surface contaminants. I expect the site to eventually be abandoned and reactors 5 and 6 to also be decommissioned.