Failed power supply at No. 4 fuel pool shows evidence of fire — Tepco says it’s “covered with soot” (PHOTOS)

Published: July 8th, 2012 at 8:44 pm ET
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15 comments


Follow-up to last week’s report: [intlink id=”just-in-kyodo-no-4-cooling-system-stopped-after-alarm-tepco-leakage-of-water-with-radioactive-materials-has-not-been-confirmed” type=”post”]{{empty}}[/intlink]

Unit 4 Spent Fuel Pool Circulation Cooling System, UPS Inside Inspection
Tepco Press Handout
July 6, 2012

Source: http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120706_03-e.pdf

h/t Fukushima Diary

Published: July 8th, 2012 at 8:44 pm ET
By

15 comments

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  2. Tepco: Unable to activate backup cooling system at No. 4 fuel pool June 30, 2012
  3. Tepco: ‘Burnt area’ on Spent Fuel Pool No. 4 secondary cooling pump (PHOTOS) June 5, 2012
  4. Kyodo: No. 4 Spent Fuel Pool’s cooling system stopped after alarm sounds — Tepco: “Leakage of water with radioactive materials has not been confirmed” June 30, 2012
  5. Tepco: Cooling system back on at Spent Fuel Pool No. 4 July 1, 2012

15 comments to Failed power supply at No. 4 fuel pool shows evidence of fire — Tepco says it’s “covered with soot” (PHOTOS)

  • Nukites

    Fire would have burned the insulation. It looks like failure of a component that did not lead to a fire. Headline is a bit of stretch.

    • TheBowRiver TheBowRiver

      — Tepco says it’s “covered with soot”

      Even in such a simple and extremely obvious case, Tepco cannot be honest.

      The FR4 PCB material has been carbonized by the failure of 1 or more components. The temperature required to create this damage over the burned area could also melt the 2 mil thick copper circuit traces on the board.

      The middle red terminal base is showing where the heat shrink boot has burned and cracked. This boot will not burn on it's own.

      It seems that there is melted material (possibly a thermo-platic potting compound) to the left of the 3 pin power semiconductors. This material appears to flow from below the Hinode 50 Amp fuse.

      With the large current flowing in this circuit, it could be that a loose screw terminal and resulting resistivity would reach a high enough temperature to cause the level of damage shown.

      The other possibility is that a power semi-conductor self-destructed into a short circuit and baked the FR4 board, causing any flamable material to ignite.

      Further to the left again you can see where some material (maybe the same as the melted material) has reached a high enough temperature to ignite causing the cracks and damage shown.

      Whatever caused the failure, and having seen this identical damage over 35 years in MRO electronics, a covering of soot explanation would be laughable if the larger Fukushima picture was not so tragic.

      • richard richard

        Hi Bow. I do wonder if there is some over translation going on. You and I know that when the smoke gets out, so does some 'soot'. So in my humble opinion I think they are fair to use the word soot, you and I may have called it carbon dust (ejection from the micro explosion within the electronics).

        It's not an unusual fault, particularly in a UPS. Particularly one that's been underspeced or compromised a little.

        I've also raised the issue before about the environment. If you've maintained any equipment, let alone electronics, within cooee of the surf (Pacific Ocean) you will have seen how corrosion is a constant headache and must always be watched.

        That, and exposure to radiation elements that are probably just as corrosive given the chance, adds up to a lower 'meantime between failure' rate.

        So a power plant on the coast should be replaced/removed in a shorter time frame then an inland plant, as the harsh environment ages the equipment.

        All that said, TEPCO should have probably done some better preventative maintenance on such critical equipment.

        Some of us even have a nose for pre-burning electronics 😉

      • iso-tope iso-tope

        Yes I agree, I have just as many years in Electronics as you do, and I know it's burned I can see it on the Spadelugs, and on the PCB. FR-4/Garolite is pretty tough stuff up to about 140C or so. It's obvious to me. It's not "just a little dusty" har har har…. Ash/Carbon and Arcing look like they happened. Just the smell of this PCB would tell the story. I know what Ozone and burning semiconductors smell like.

  • e_saula

    I agree with Nukites,Sparks and burns on the electronics circuits boards due to shortcircuits or components overheating but definitely no fire in the panel.

  • TomSmall

    I look at that crummy circuit board, and there's my life in the balance. Maybe you don't like Tepco; I look at that and I see General Electric, and their money, and that's what I'm going to die for? Well, I'm not dead yet, but General Electric ought to wish I were.

    • flatsville

      Yes agreed. And I have to wonder how many of those Uninterruptible Power Supplies they hold in reserve since the are obviously interruptible. I would want at least a dozen sitting in back-up supply.

  • hanaloa hanaloa

    Where thereʻs smoke…

  • iso-tope iso-tope

    holy 1@#!@. That's not "soot". That's burned electronics.

  • iso-tope iso-tope

    The worlds fate boils down to a Simple and Typical 19 inch Rackmounted
    UPS that most server rooms have (SMALL AND UNDERPOWERED), and the backup UPS is also TIED to the same battery as the Primary to boot (read other releases), running this "system". Anyone can see how inadequate this is… . Who through this stuff together? Another example of they do not know what they are dealing with. Toothpicks to fight a giant. It would not shock me at all if it burned out because of inadequate cooling, and running non-stop and overheating. Which means it will definitely happen again.

  • iso-tope iso-tope

    The worlds fate boils down to a Simple and Typical 19 inch Rackmounted
    UPS that most server rooms have (SMALL AND UNDERPOWERED), and the backup UPS is also TIED to the same battery as the Primary to boot (read other releases), running this "system". Anyone can see how inadequate this is… . Who through this stuff together? Another example of they do not know what they are dealing with, or know what they are doing at all.. Blind leading blind, and lying about it. Toothpicks to fight a giant. It would not shock me at all if it burned out because of inadequate cooling, and running non-stop and overheating. Which means it will definitely happen again.

  • iso-tope iso-tope

    and it bears a remarkable resemblance to the "Mysterious Black Dust" which is radioactive. Except that I can see some burned Spade lugs on the terminals.

  • e_saula

    There is a possibility of more serous problems inside the entire control panel being supplied by the damaged UPS,which TEPCO is not disclosing.They should be honest enough to tell the world if there are other damaged/malfunctioning components in the entire panel as this magnitude of arcing could have been as a result of shortcicuits/overheating caused by components deterioration/failure elsewhere in the panel particularly along the loadline,and until such components are detected trough troubleshooting and replaced,putting dozens of backup UPS one after the other will still lead to exactly same thing as we are seeing,and possibly real fire of magnitude that cannot be covered up.By that time,it might just be too late!

  • bluerthanblu bluerthanblu

    In Mochizuki's 'Settlement Report 7/6-7/8' he states: The burnt UPS is actually for computer servers, and it can’t be used to nuclear plant." Still, short circuits starting fires in unprotected equipment or gas filled rooms is not good. Electrical equipment put in rooms that are below sea level doesn't make sense either. Fukushima Diary mentions, on same page, that on 7-9, a tweet from a person in Tsukuba, Ibaraki reads, "Well, there hasn’t been any earthquake report since 20:34 of yesterday, but the house has been all shaken. What is that ? Is the ground slowly moving ?" Liquefaction and ground settling will create great stress on R4 sfp by destabilizing the bldg structure and further flooding equipment in basement. Tepco now races against time to keep R4 bldg upright. May luck be on their side, after so many months delaying preventative measures. Meanwhile Japan government races to start more reactors! It's all about project promises and money, nothing else it seems- :/

    http://fukushima-diary.com/2012/07/settlement-report-7678/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+FukushimaDiary+%28Fukushima+Diary%29