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Thread: Fukushima

  1. #61
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    Quote Originally Posted by Brian Elfert View Post
    A nuclear plant produces electricity. Why does a plant that produces electricity need a constant connection to the grid or backup generators? How come the plant wouldn't make its own power to keep the cooling and such running?
    Brian
    They do, but the rub is that they still need to be connected to the grid.
    The output for a US "Nuke" plant is 345,000 volts and 100's of megawatts, which is connected to the grid in such a manner that all of the turbines on the grid are in sync. A power plant by itself is too small a load by itself to run electrically when presented to the main generator output, and still maintain thermal efficiency of the reactor itself, so the power is sent out and back, so to speak. The power for the pump motors is 6.9KV, and 4160, so the voltage has to be stepped down for motor operation. It's pretty involved actually
    In the event of grid instability, which happened at Fukushima, the plant disconnects itself from the grid by virtue of a turbine trip, once the generator output breakers are opened.
    Once disconnected from the grid, and in the absence of power on the grid, the back up generators start to power the electrical busses required for safe shutdown and continuous plant operation to maintain reactor core integrity. It is a layered approach based on redundancy for safety margin.
    These backup power supplies, diesels, at US plants are tested, and surveilled, continuously. The inability to demonstrate that back up power systems are available 24/7 will force the owner/operator of a plant to shut down, administratively, to meet regulatory requirements. The diesels are a very big deal at US plants.
    Last edited by Mike Cutler; 01-02-2014 at 4:56 AM.
    "The first thing you need to know, will likely be the last thing you learn." (Unknown)

  2. #62
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    Quote Originally Posted by Ken Fitzgerald View Post
    Discussing nuclear reactors or nuclear safety isn't political until you start laying blame on governments etc.

    It's just like discussing economics. It's not political until you start laying blame on governments or political parties.
    Yeah, but...just because we're not laying blame on them doesn't necessarily mean that it's not their fault.

    Quote Originally Posted by Ken Fitzgerald View Post
    I didn't say "all men"........
    I am never wrong.

    Well...I thought I was wrong once...but I was mistaken.

  3. #63
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    Dave, Mike, Ken, and anyone else with nuclear experience:

    Do you see the US at risk? I know nothing about nuclear energy, electricity, ocean currents, etc.. I read reports of thousands of gallons of waste that has been dumped every day since the disaster. Other reports of radioactive clouds and radioactive fish have surfaced. I am sure there is drama here to sell the news, however, there is usually a thread of truth in every story. Based on your knowledge, do you see this as affecting the USA? What do you see as any problem for us?

  4. #64
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    Quote Originally Posted by Harold Burrell View Post
    Yeah, but...just because we're not laying blame on them doesn't necessarily mean that it's not their fault.



    Doesn't mean it is their fault either. (For some reason, I can't post a emoticon here so imagine me rolling my eyes and then smiling.)
    Ken

    So much to learn, so little time.....

  5. #65
    It's a hard call to make Ray,

    Radiation covers a lot of factors, persistence of the emitter (short or long half lives) how and what it emits (Alphas, Betas, Gammas etc) and the distribution of those by products. Toxicology is another factor (how biologically toxic the by products are) as chemicals rather than isotopes. Granite for example is radioactive as is Vaseline glass but many homes have this as decoration even today without any safety fears.
    As things stand with the Diachi plants I wouldn't have too many concerns, the situation is rather fluid though and further accidents or building collapses could make a unpleasant situation very serious very quickly. TEPCO being less than down the line with their information certainly hasn't helped and in the early times after the accidents honesty would have made the situation easier to deal with or at least allowed those trying to deal with it to make more informed decisions.

    The biggest problem with Light Water Reactors and Breeders is you are constantly fighting to keep them under control, they aren't "walk away safe" and when systems fail the outcome can be very serious as we have seen. Dealing with the by-products such as radioactive Xenon that poisons the core is a constant battle. I'm sure Mike will agree that the constant fear is run-away or heaven forbid, Meltdown if there is a failure in the control or command train.
    Molten salt reactors are walk away safe, all the efforts in an MSR are directed at keeping the reaction going rather than trying to stop it going too far, if you "walk away" the entire system shuts down quite quickly. The fuel is already a liquid so meltdown isn't a problem. There are problems (they are seeded with 233 that has to be produced), the fuel is highly corrosive and great care has to be exercised to prevent cracking of the Graphites but in the scenario of a tidal wave, an earthquake, terrorist event or a plane dropping on the reactor building the entire system goes into shutdown rather than run-away. There is no Hydrogen produced (no big explosions like Daichi) and the reactor vessel runs at atmospheric pressure.

    Looking at the US annual dose figures the biggest offender is natural Radon @ 55% of your annual intake emitter, 3% comes from previous nuclear testing with less than 0.4% coming from the nuclear industry. The problem with the media is the leaps they make when discussing the event, many types of radiation are harmless (effectively) but because they are still radiation the media tends to ignore their lack of danger and just tell half the story scaring people silly. For any source (emitter) the critical information is how much and the type of radiation that it puts out and this is what gets over looked or ignored.

    Hi Mike,

    From what I've seen the 100Mw system is really a test bed, the biggest proponent of it is the former leaders son who has managed to get quite a few mainstream guys onboard and base funding for the experiments. I'm really hoping it will pan out and lead to other nations doing more dedicated work. At the moment the efforts seem to be around single fuel types with lower efficiency but the last I heard they are looking at the two fuel systems, how far they will go I have no idea. The MSR technology if it is exploited it going to lead to interesting times indeed

    cheers

    Dave
    You did what !

  6. #66
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    Raymond,

    I'm not qualified to respond to that but until I see a majority of nuclear physicists and engineers concerned, I am not going to worry about it.

    IIRC it was stated earlier that the dangers from Chernobyl were greater than those from this accident.

    Understand that my training was from the safety and measurement standpoint. How to recognize, measure, plot radiation and what safe levels were. A lot of the training we took was generic so we learned about all forms of radiation. In the course we also learned about safe shielding for different types of radiation. It really is a complex matter and with a lot of variables. It's complex enough we had to retake courses and recertify annually.

    Among scientists, nuclear physicists and nuclear engineers, which I am not, there can be disagreements about accepted theories. That is why I have stated I will not get concerned until I see a majority of those professionals get concerned.

  7. #67
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    Quote Originally Posted by Raymond Fries View Post
    Dave, Mike, Ken, and anyone else with nuclear experience:

    Do you see the US at risk? I know nothing about nuclear energy, electricity, ocean currents, etc.. I read reports of thousands of gallons of waste that has been dumped every day since the disaster. Other reports of radioactive clouds and radioactive fish have surfaced. I am sure there is drama here to sell the news, however, there is usually a thread of truth in every story. Based on your knowledge, do you see this as affecting the USA? What do you see as any problem for us?
    Raymond
    The event is extremely serious,and there is no one that would tell that somehow, in some minute amount, we would not see some measurable level of activity from this event. Everything can be measured and quantified mathematically, so the math would state that there has to be some level of consequence. It's that level that is important, and as of yet I haven't read of any measurable level that would be of dramatic concern. This is not to diminish the seriousness, as this event will have long term consequences for generations going forward.
    The Pacific Ocean is enormous and it is deep. Heavier particles will sink and fall into the sand. The saltwater and cold temps of the ocean will act as a natural moderator, or shield. While thousands of gallons can be dumped into the ocean, the important fact is what is the activity level of the water as measured in micro curies per cubic liter. I believe the Japanese use seiverts instead of curies though.
    I'm more worried about unscrupulous people and that they would somehow scavenge material from the area and get it into the mainstream market places. That would be a problem.

    In your opening post you questioned why no one was doing anything about the event. I can assure you that governments, and nuclear utilities, all over the world are helping the Japanese in any way they can.
    Last edited by Mike Cutler; 01-03-2014 at 9:00 PM.
    "The first thing you need to know, will likely be the last thing you learn." (Unknown)

  8. #68
    I'm more worried about unscrupulous people and that they would somehow scavenge material from the area and get it into the mainstream market places.
    Happened a few times from memory Mike, Spain and Brazil? Gamma sources improperly disposed of that got back into the scrap metal chain and a few deaths involved?

    I guess the length of the potential problem is the issue, even the mid life sources are going to stay around for 600 years (131 / 137) with the Pu for 1/2 a million or so. The last figure I saw was just under 4Kg for Ceasium - 137 released at Fukushima compared to 28Kg for Chernobyl.

    cheers

    Dave
    You did what !

  9. #69
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    Quote Originally Posted by Dave Sheldrake View Post
    Happened a few times from memory Mike, Spain and Brazil? Gamma sources improperly disposed of that got back into the scrap metal chain and a few deaths involved?

    I guess the length of the potential problem is the issue, even the mid life sources are going to stay around for 600 years (131 / 137) with the Pu for 1/2 a million or so. The last figure I saw was just under 4Kg for Ceasium - 137 released at Fukushima compared to 28Kg for Chernobyl.


    cheers

    Dave
    Dave
    It just happened in Mexico a month or so back. All the Police had to do was wait until the thieves showed up in the hospitals with radiation poisoning. It didn't take long, about a week.
    People can be foolish sometimes.
    "The first thing you need to know, will likely be the last thing you learn." (Unknown)

  10. #70
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    WOW - I never thought about people gathering material and trying to use or sell it. Kinda like the scenario in the movie Sum of all fears. Hopefully, that will never happen here.

  11. #71
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    Quote Originally Posted by Dave Sheldrake View Post
    You must be kidding me!! some idiot got paid to write that up!

    Absolute rubbish!

    Dave
    My guess is a gen y junior "journalist"
    Sent from the bathtub on my Samsung Galaxy(C)S5 with waterproof Lifeproof Case(C), and spell check turned off!

  12. #72
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    Quote Originally Posted by Raymond Fries View Post
    WOW - I never thought about people gathering material and trying to use or sell it. Kinda like the scenario in the movie Sum of all fears. Hopefully, that will never happen here.

    Sum of all fears was at least written well, by comparison that is, this "article" (i'm being really generous with categorising it) was written by an idiot.
    Sent from the bathtub on my Samsung Galaxy(C)S5 with waterproof Lifeproof Case(C), and spell check turned off!

  13. #73
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  14. #74
    Great find Dan

    The responder "Nutronium" has it bang on the money, excellent work and accuracy all round in his posts.

    I loved the comment about "Licking glow in the dark dials"

    cheers

    Dave
    You did what !

  15. #75
    Quote Originally Posted by Raymond Fries View Post
    WOW - I never thought about people gathering material and trying to use or sell it. Kinda like the scenario in the movie Sum of all fears. Hopefully, that will never happen here.
    Hi Ray,

    Some of the locals in Laos are still making ornaments from and selling UXB's without regard for what things like MK82's do when they go boom. If there is $$$ to be made some people will take inordinate risks for very little return Currently the death rate is around 300 a year from "recycling" accidents.

    Fun facts,

    If you managed to eat enough Bananas then you could give yourself radiation poisoning from Potassium - 40
    Antistatic brushes for cleaning photographic film contains Polonium - 210
    Thorium Oxide is used in Gas Lamp Mantles
    Smoke detectors contain Americium - 241 with a half life of 458 years
    Fluorescent lamp starters contain Krypton - 85 (a Beta & Gamma emitter with a 10.5 year half life)
    Cerium Oxide used for polishing often contains Thorium Oxide
    Glow in the dark watches made in the 50's can liberate up to 50 counts per minute due to the Radium used in the paint
    From the 60's Tritium was used (a radioactive form of Heavy Hydrogen, H3) with a half life of just over 12 years OR Promethium - 147 with a 2.6 year half life, both are Alpha & Gamma emitters

    Seeing how most of the human race (not to mention all the worlds monkeys) haven't all died from Radiation poisoning it's a pretty safe bet that there are other factors involved before getting too concerned about the big "R" word

    cheers

    Dave
    You did what !

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