Japan’s giving up on salvaging some reactors.

If they’re using seawater for core coolant now, they’ve pretty much written off ever putting those reactors back in service.

American nukes, and I presume Nipponese ones, have a “last-resort” system that is heavily borated water.  Boron is a “neutron poison”.  Actually it loves neutrons, sponges them right up, so more accurately it’s a “fission poison”. It’s for stopping runaway supercriticality.

No one’s ever had to use that system, and quite likely no one ever will. It’s like slitting your reactor’s throat. Just go ahead and mothball it after the emergency, ’cause you’re never getting all that boron out.

But even borating their coolant wouldn’t solve Japan’s problem. I sure there’s still plenty of free neutrons whinging around the fuel masses, but fission’s not the issue.  It’s heat building up from radioactive decay. If you can’t carry the excess off, the temperature will rise until the fuels rods degrade, or even melt.

As long as possible, they’ll try to recover in a manner that would saves the reactor for future use.  If they’re pumping seawater now…whew.  That’s probably like the boron system, except you’re cutting the throat much more slowly.

What I want to know is, where did all their non-seawater go?

About wormme

I've accepted that all of you are socially superior to me. But no pretending that any of you are rational.
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4 Responses to Japan’s giving up on salvaging some reactors.

  1. SeanB says:

    Probably was in a pond that supplied a filter and then a RO plant before being distilled ( just a guess as the easiest way to make really large volumes of pure water cheaply, especially if you have a lot of low grade heat around from say a nuclear reactor to provide the boiling at atmospheric pressure or around that for final distillation of the pure RO water) which was either damaged, washed away or filled with sea water and assorted mud and debris. They then had no ability to run high pressure pumps as they had no power, so a RO system would either run at a very low rate or not at all, especially if the input water is very dirty and fouls the membranes or blocks the pumps which expect clean municipal water, and which probably were at a low level and were swamped with salt water, making them inoperable. Thus they were left with whatever was in the holding tankage and in the emergency systems, with water boiling off and being released as steam to control pressure causing this to run out. They probably took the fire fighting water supply as an emergency measure, as they could always use sea water for fire fighting, the pumps would not like it but would last long enough. Using sea water meant they were writing the reactor off, as you would find it is cheaper to build a new one than clean and refurbish the old one after it has had hot salt corroding piping never meant to be exposed to it.

    • wormme says:

      I guess what I really meant was, are they containing the activity the water picks up in cooling down the fuel and core? You can let enormous amounts of noble gases be vented, but other activation products?

      Well, I’m still confident that there won’t be radiological deaths, even with major rad releases. It might cripple any hope of nuclear expansion for decades, though. Even with CO2 concerns.

  2. Leopold says:

    Didn’t the Japanese have a criticality event at one of their plutonium reprocessing facilities back in the 90’s? I recall hearing the news report about the workers seeing a blue flash and thinking, “Cherenkov radiation; they’re dead.” Did the people farther away from the event get tested/monitored and did we learn anything useful about whole body gamma exposure?

    By training, I am a high energy physicist (not practicing since the SSC got canned) and I firmly believe the linear, no-threshold model is an evil as great as the bogus science that got DDT banned, so I am finding these posts to be a very welcome thing indeed.

    • wormme says:

      Here’s the Wiki on that. Two of the three operators died, hundreds were evacuted. Others in the plant picked up over two rem. That’s known due to their TLDs; someone could pick up that dose and would never know.

      That’s the most recent rad fatality I’m certain of, but probably there’s been radiography-related deaths in less heavily regulated nations. I don’t think we’ve had a life-threatening radiography incident here in decades.

      Sorry about the SSC. They were really trimming RHIC’s funding back when I left Brookhaven.

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