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How has your opinion on the safety of nuclear power changed after the events in Japan?

Displaying poll results.
Not at all.
  21965 votes / 39%
It seems slightly safer than I thought.
  5881 votes / 10%
It seems much safer than I thought.
  5087 votes / 9%
It seems slightly less safe than I thought.
  6314 votes / 11%
It seems much less safe than I thought.
  4304 votes / 7%
I read a few Wikipedia pages and I'm now an expert.
  6136 votes / 11%
I am preparing a Godzilla-proof bunker.
  5874 votes / 10%
55561 total votes.
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  • Don't complain about lack of options. You've got to pick a few when you do multiple choice. Those are the breaks.
  • Feel free to suggest poll ideas if you're feeling creative. I'd strongly suggest reading the past polls first.
  • This whole thing is wildly inaccurate. Rounding errors, ballot stuffers, dynamic IPs, firewalls. If you're using these numbers to do anything important, you're insane.
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How has your opinion on the safety of nuclear power changed after the events in Japan?

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  • by Gordonjcp (186804) on Monday March 14, 2011 @08:47PM (#35486556) Homepage

    We just need to invest some time and money building new nuclear plants that aren't based on 1950s reactor designs.

    Would you have bought a diesel car 30 years ago? Not unless you were a taxi driver. Would you even give petrol a moment's thought today? No chance!

    • by Ksevio (865461)
      Is that a jab at us Americans who are only now starting to get diesel cars?
      • by sodul (833177)

        We're getting electric and hybrid cars faster than diesel.

        One of the problems with diesel in the US is the lack of supply, kind of like the natural gas cars in europe.
        Diesel is less taxed in europe, at least in France, where it is significantly cheaper than regular gazoline. In the US diesel is actually more expensive than gasoline most of the time. A lot of people would probably destroy their diesel engine as well. I saw a few people put gasoline for their diesel during my time in europe, at best the car w

        • Diesel?!? (Score:5, Insightful)

          by ackthpt (218170) on Tuesday March 15, 2011 @12:44PM (#35493158) Homepage Journal

          Some very young people on here. And I'm showing my age.

          A couple decades ago some bright people at the Big Three noticed diesel fuel was far less expensive than petrol (gas) - it was only used by transport and construction companies.

          As a byproduct of refining petroleum it was underutilized and in ready supply - produce millions of gallons of lighter hydrocarbons from the mixture that is raw petroleum and you will have lots of it. Something few people consider is that Petroleum is a homogeneous mixture of hydrocarbons from the very light, such as C8, to the very heavy (depending upon the source) Asphaltics, C40 to 70. Fractional Distillation of a barrel of raw petroleum produces a wide range of potential fuels and other compounds.

          So the Big Three shifted to production of diesel automobiles, promoting them as less expensive to operate. Consumers purchased them and then the darnedest thing happened, the price of diesel fuel went up! I mean, seriously, just because there's an increase in demand a price shouldn't go up, right?!? Well that seemed to be the prevailing logic.

          Reduce dependence upon nuclear fuel for power plants and that energy will have to come from somewhere - Hydro? Solar? Wind? Geothermal?

          Never, ever suggest using less energy, though. That could lead to Socialism (or even Communism, as detected in lab mice.)

          • It didn't help that all the big three diesels were complete shit either.

          • Reduce dependence upon nuclear fuel for power plants and that energy will have to come from somewhere - Hydro? Solar? Wind? Geothermal?

            So I read a few Wikipedia pages and am now an expert.

            The first post was right: the breeder reactors in question are based on pretty much the oldest nuclear technology available, which was meant to produce weapons-grade plutonium. These days there is a race to develop mini-reactors producing on the order of 100MW that can run for decades on depleted uranium (once the initial reaction begins) without refueling or requiring external power sources for cooling. Miniaturization is once again the future.

            That is

    • I disagree with your argumentation and interpretation of the poll.

      We just need to invest some time and money building new nuclear plants that aren't based on 1950s reactor designs.

      Would you have bought a diesel car 30 years ago? Not unless you were a taxi driver. Would you even give petrol a moment's thought today? No chance!

      I thought that the question included all those 1950's reactor designs, because they're all still operating? I hadn't realized how many are built right on top of active faultlines, so my opinion about nuclear has seriously gone down.

      I think nuclear energy is very unsafe at the moment. Aging reactors which are kept open using some nuclear version of ducttape, because it's completely unaffordable to dismantle them, are a growing risk.

      It's also a

    • by Rakshasa Taisab (244699) on Tuesday March 15, 2011 @06:52AM (#35489374) Homepage
      Just as safe as ever?... Those 40 year old reactors survived a 9.0 quake and the only reason we're in problem now (how ever slight, the radiation leakage isn't that scary yet) is that they messed up by putting the diesel generators the wrong place.
      • by nyctopterus (717502) on Tuesday March 15, 2011 @09:10AM (#35490214) Homepage

        I voted less safe, even though I agree new nuclear plants are certainly safe enough for me to support them, and here's why: I wasn't aware that Japan, one of the richest countries in the world, was running 40 year old reactors in the first place. I am surprised they screwed up with the generator location, and didn't recognise or fix the problem until now. I am surprised that this quake and tsunami was able to do the damage it did to the nuclear reactors, given that a tsunami hits Japan every six years on average, and everyone in the world knew that a big earthquake was on the cards.

        So the current state of nuclear is less safe than I would have thought.

      • by TheCoders (955280)

        they messed up by putting the diesel generators the wrong place.

        That's kind of the point, isn't it? These plants have the potential to cause mass death, and we're counting on every engineering decision being perfect. From this incident we learned something about the placement of the generators. What are we going to learn from the next incident? My point is we can't rely on trial and error here.

        • by muridae (966931)

          Gas and coal fired power plants have the potential to cause mass death, should the fuel stores on site catch fire. Oil refineries can blow up and kill lots of people. Buses and planes can crash, so can individual cars. About the only power sources that don't have the potential to catch fire are wind and solar. Solar panels do have a good bit of cadmium, usually.

          Should we stop using everything that has a rather rare, once in a hundred or thousand year chance of causing the loss of a life?

      • How ever slight... One of the reactors' cooling system is down, and backup failed. It's warming up, but it's under control, Actually, it's not really under control, something just went kaboom, don't worry, that was just some hydrogen, part of the plan. Radiation went up a little, but don't worry, it seems to be going down again. O, one of the other reactors' cooling systems is also down. O well, no problem, still no significant radiation. The reactors are all still submerged, as long as that's the case, th
      • by AmiMoJo (196126) <mojo@world3. n e t> on Tuesday March 15, 2011 @11:19AM (#35491934) Homepage

        This is an incredibly important point that seems to have been missed. Well, two points actually:

        1. Japan survived a magnitude 9 quake, one of the biggest ever, with barely a scratch. Buildings stayed upright and didn't become unsafe, damage was minimal and superficial. No trains crashed, the few fires were dealt with quickly and AFAIK not a single person died. From my hotel window I can see the brand new Tokyo Sky Tree, which is 634m tall, and it isn't even finished yet. There are still cranes on it, right at the time. Nothing fell down. Japan is about as earthquake-proof as it is possible to be, and these reactors shut down safely as designed.

        The problem is the unprecedented tsunami which overwhelmed sea defences (that worked well against all the other tsunami over the years) and swamped the diesel generators, preventing proper cooling.

        2. The amount of radiation is still very low and not considered harmful, except for at the power station itself. Even in the worst possible scenario where there is complete meltdown the contamination will not be spread like it was at Chernobyl because the reactor won't explode.

        The situation is serious but not capable of developing into a major disaster.

        • Re: (Score:3, Interesting)

          The cores are not the problem, the problem is the spent fuel. A spent fuel storage pool without water will spontaneously combust, and in the design of those Japanese reactors the roof above them is almost irrelevant (and after it's blown away by a hydrogen explosion completely irrelevant).

  • by Iamthecheese (1264298) on Monday March 14, 2011 @08:47PM (#35486562)
    Nuclear power seems slightly less safe to me now: I was surprised to learn how old many active reactors are. On an unrelated note, nature has scared me into wanting that bunker.
    • Re:Godzilla (Score:4, Insightful)

      by c.r.o.c.o (123083) on Monday March 14, 2011 @09:42PM (#35486980)

      Nuclear power seems slightly less safe to me now: I was surprised to learn how old many active reactors are.

      We have so many old reactors still active because after Three Miles Island and Chernobyl the peons panicked and blocked any new reactors from being built. In effect, the vast majority of nuclear plants active today were built before 1980.

      In the meantime our energy consumption skyrocketed, coal and gas power plants simply do not have the capacity to replace nuclear. Not to mention that they are much more damaging to the environment than nuclear plants.

      And don't get me started on green energy. It's wonderful, until you realize you'd need to cover the entire surface of the US with windmills to provide enough power to replace nuclear, coal and gas.

      • Re:Godzilla (Score:4, Insightful)

        by joocemann (1273720) on Monday March 14, 2011 @11:17PM (#35487560)

        Your last line is complete B.S. and gives clear evidence that you don't know the science behind green energy but rather the political memetics spewed by pundits. Anyone watching the science knows its easily feasible. Brazil is over 80% powered by 'green energy' and yet they are not covered in windmills. I'll wait while you go google up Brazil's energy infrastructure and some pundit sputem to attempt to rebuke what I said. I won't be digging up all the scientific pubs, but take this as warning that they're out there.

    • I too was surprised at the problems they are having. But now I'm more confused:
      Initially, I thought that dropping the control rods stopped the reaction almost instantaneously.
      Then I read that in Japan the problem they are having is that it takes time for the reaction to stop after the reactor is shut down, thus the slow partial meltdown they are going through.
      Then, to respond to this, I checked Wikipedia on scramming and it says that it is almost instantaneous.
      So now I'm just confused.
      Either way, I
      • Re:Godzilla (Score:5, Interesting)

        by TopSpin (753) on Tuesday March 15, 2011 @03:11AM (#35488574) Journal

        I thought that dropping the control rods stopped the reaction almost instantaneously.

        Control rods control only the primary reaction; splitting Uranium atoms by knocking them with neutrons. Fission is, however, rather messy. When an atom splits it becomes two or more different elements. Those elements are typically weird and unstable isotopes (atoms) that then spontaneously decay (regardless of the state of the control rods) again and again until they reach some (relatively) stable state. Unfortunately this takes some time and each decay event radiates energy which creates more heat. When someone says dropping the control rods stops the reaction it is implied that only the primary reaction is actually halted; the byproducts of that reaction continue to decay spontaneously.

        This is why the reactor continues to produce a lot of heat immediately after scram. The amount of heat radiated after scram is sufficient produce the catastrophe we see today. Cooling must be provided to prevent this.

        Either way, I would have thought that they could and would have shut down the reactors a long time ago, like, while the tsunami was on its way or even when they realized the pumps were flooded.

        The reactors scrammed immediately with the earthquake. As you should now understand this isn't sufficient to safe the reactor; cooling must continue for days after scram. This is usually done with 'off-site' power supplied by another power plant. That wasn't available because of the earthquake. Backup power generation should have then provided sufficient power to cool. This equipment was incapacitated by a huge tsunami that appeared about ten minutes after the earthquake. Batteries are then expected to provide temporary power. Batteries die.

        Now we have achieved the condition known in the reactor business as 'blackout.' No off-site power, no backup power. No power means no circulation and no cooling.

        At this point you're stuck. The reactor is overheating and overpressure. You must release pressure to keep the reactor vessel from rupturing (because a nuclear powered radioactive steam explosion is undesirable.) Releasing pressure means releasing coolant. Coolant loss exposes fuel. Exposed fuel overheats and causes a chemical reaction that produces clouds of pure Hydrogen. The Hydrogen accumulates someplace until it burns (blows up.) The explosions do fun things like put your staff in the hospital (15 so far) and knock out the fire pumps you've rigged up to supply coolant to the reactor (4 of 5 on Monday.) Equipment failures and mistakes continue apace as usual but now you have no margin for error; when some valve fails during normal operation the operators have an array of responses. A valve failure or inadvertent actuation during a blackout means you expose the core, as happened late Monday.

        Meanwhile a spent fuel pool in an otherwise safely shutdown reactor (#4) catches fire due to lack of circulation and contaminates the site with enough radiation to sterilize mammals. The damn island won't stop moving either. Several times a day a 5+ aftershock tests every piece of equipment you care about. The tsunami wiped out most of the out-buildings where you kept the tools and spare parts you might have used to fix things. Folks show up with various forms of emergency power generating equipment, but it's all the wrong voltage, phase or current capacity so it doesn't just hook up; you go into engineer mode and decipher 40 year old technical material to get it wired up. Anything you break is irreplaceable. Turn your back and generators run out of fuel.

        Did your family survive the waves? They were only a few kilometers inland...sure would be nice to leave and find out. Oh, wait.

        To the pole question; my opinion hasn't changed about the safety of nuclear power. It isn't safe. It is, however, worth it. That some risk should accompany great power seems fitting. Japan salvaged itself from a ruined militar

        • by Thelasko (1196535)

          To the pole question; my opinion hasn't changed about the safety of nuclear power. It isn't safe. It is, however, worth it. That some risk should accompany great power seems fitting.

          Power, [wikipedia.org] in general, [guardian.co.uk] is dangerous. [wikipedia.org]

          Pick your poison.

        • by AmiMoJo (196126)

          The opposition to nuclear power isn't just about danger, it is about nuclear non-proliferation and the debatable problem of spent nuclear fuel and contaminated waste.

          Without going into the waste issue non-proliferation seems like a good idea. Unfortunately the only other non-renewable options are coal and gas, both of which have their own major problems. Renewable, on the other hand, could potentially deliver all the energy we need once sufficiently developed and without massive changes to the landscape or

        • by Alef (605149)

          No power means no circulation and no cooling.

          Does anyone here know why the power plants are/were not designed to use the stream pressure to drive the cooling pumps? I mean mechanically, with a steam turbine connected directly to the pump shaft. No need for lots of electrical power, and the hotter the core gets the more power you have to pump.

          I'm presuming there is a good reason why it isn't practical, because it seems like an otherwise rather obvious thing to do.

    • Re:Godzilla (Score:5, Insightful)

      by AmiMoJo (196126) <mojo@world3. n e t> on Tuesday March 15, 2011 @05:22AM (#35489078) Homepage

      You might also be surprised how many fairly old aircraft are in use. Non-engineers tend to think that things inevitably wear out and have to be replaced, but that isn't necessarily the case. Aircraft can be flown indefinitely and safely as long as they are maintained correctly, and similarly so can nuclear reactors. What tends to take them out of service is parts and skills becoming harder to get or the on-going cost of maintenance making buying/building a new one a better option.

      As for nature Japan has proven itself to be fairly earthquake proof - few if any buildings collapsed in the quake. I am in Tokyo at the moment and when it hit I never felt scared at all, despite being on the 5th floor of a tower block. Buildings moved (as designed) but there wasn't much damage and it didn't seem that big of a deal at the time. What did all the damage is the tsunami and there is now a lot of discussion about what can be done to defend against them in the future. Japan has sea defences because there are regular tsunamis, just none this big. I'm sure that in time this country will be as well protected from large waves as it is from large earthquakes.

    • Re:Godzilla (Score:5, Insightful)

      by Drethon (1445051) on Tuesday March 15, 2011 @10:23AM (#35491222)
      Have you considered what will happen to an underground bunker in a tsunami?
  • by thomasdz (178114) on Monday March 14, 2011 @08:52PM (#35486620)

    "a 41 year old nuclear reactor gets hit by a 9 magnitude earthquake, then slammed with a 2 ft. tall swell, followed by an explosion due to the buildup of hydrogen gas that blows off the roof of the building, and the core is intact and contained. And you are telling me nuclear power isn't safe?"

    Anyway... I wish Tritium cycle nuclear power would start getting some R&D
    Time to retire the Uranium & Plutoniums reactors

    • by thomasdz (178114) on Monday March 14, 2011 @09:32PM (#35486890)

      "2 ft." should be "20 ft."
      (yeah yeah...I mean 7 meters)

    • by fermion (181285)
      This is why I chose less safe. If we are designing for a all scenarios, then we should no play victim after the fact and blame 'unexpected weather'. This is what happened at Heathrow and it is simply a means to distract from incompetence.

      Due to the severity of the event, we forgive the failure of the secondary containment. What is not is the lack of coolant. If just the generators has failed, ok. But to say there is no way to manually inject water to prevent meltdown is not ok. In engineering we exp

  • It's not just hype, it's a big deal. But next to the humanitarian crisis in Japan, it'll probably amount to small potatoes. At least a 2,414 killed and 3,118 missing. [npa.go.jp]. It's never a bad time to donate to the American Red Cross [redcross.org]. Or UNICEF [unicef.org]. Or whichever charitiy you prefer based on your locale.
  • by c.r.o.c.o (123083) on Monday March 14, 2011 @09:22PM (#35486822)

    It was not human error, it was not a faulty design. It was one of the largest earthquakes and tsunamis recorded in recent history, and the largest event to EVER hit a nuclear plant. The fact that the reactors did not suffer a catastrophic meltdown yet is a testament to how reliable and ultimately safe nuclear technology is in Japan, but also to how dedicated the engineers working there truly are. My thoughts go out to those people that as we speak are inside the plant, trying to maintain a constant flow of water to cool the reactors in spite of the radiation and dangers. Like the soldiers in Chernobyl, they truly are heroes.

    Bear in mind the Fukushima plant is built on the ocean side, and took the full force of the earthquake and the tsunami. There are risks inherent to nuclear reactors, but those engineers have shown that good designs and responsible usage can limit damages even in the face of an unprecedented force of nature. Even with the outer buildings blown to pieces radiation leaks have so far been minor, and the reactor containers are intact.

    I thank them on behalf of the world, I wish I could be there to help.

    My poll choice is irrelevant, but I hope all the nuclear plants in the world are at least as well built and manned.

    • Re: (Score:3, Interesting)

      by assertation (1255714)

      It was not human error, it was not a faulty design.

      Maybe not human error, but willful negligence, the kind that we see happening in our country all of the time which makes me not want to take a chance on nuclear power.

      Japan's deadly game of nuclear roulette
      http://search.japantimes.co.jp/cgi-bin/fl20040523x2.html [japantimes.co.jp]


      After visiting the center a few kilometers from Hamaoka, I realized that Japan has no real nuclear-disaster plan in the event that an earthquake damaged a reactor's water-cooling system and trigger

  • Before this happened, I was under the impression that most reactors were designed to be passively safe. That is, when the power shuts down the control rods slide into place and the reaction slows below some very conservative safety margin. Given that the design at Fukushima requires active cooling of the core even in a shutdown event, that makes me question the basic premise of that particular design. If a fuel rod surrounded by control rods is generates enough heat to permanently damage the reactor without active cooling, then that indicates bad safety engineering.

    While I still like the idea of building more nukes, this incident makes me more interested in understanding the failure modes of the "tried and tested" designs both in plants and on the drawing board for new plants, and whether they are susceptible to the same problems should the active cooling system fail, whether due to natural disaster, sabotage/terrorism, or just plain bad luck.
    • by Narcocide (102829)

      Unfortunately this is the case for pretty much any nuclear power plant in current operation. Safer [slashdot.org] reactor designs do exist but it seems to me like the massive investment that was required to research and build the old reactor designs coupled with the massive cost and risk of disassembling them has held back progress on adoption of the new technology anywhere it could be used to replace existing reactors. Sad.

    • by dgym (584252) on Tuesday March 15, 2011 @12:00AM (#35487780)
      These reactors are designed to be passively safe. When the control rods slide into place the main reaction stops and it is safe to walk away. With them in place and a cooling failure all you will get is a harmless meltdown, which is a low temperature affair where the entire core gets wrecked but is easily contained by the containment shell.

      One reason that people are working to maintain adequate cooling is because a meltdown puts the containment shell to the test. This is a test that it should handle with ease as meltdown temperatures are around the 500C mark and the shell can withstand over 2000C, but it would still be better not to have to test it at all.

      Another reason is that a wrecked core is a significant financial loss - in terms of the core, all the useful material it still contains, and the difficulty of cleaning it up. If cooling is maintained perfectly then everything can be saved. Even by resorting to sea water for cooling (which makes the core permanently unusable) the system can be cleaned up easily, and the fuel can be reclaimed.

      Of course people are still evacuating and for a very good reason. An unparalleled disaster has just wiped out all the backup facilities necessary for a clean shutdown. There is now the potential for a meltdown, which means that the last line of defense (the containment shell) would be tested. As reliable as containment shells have proved to be there is simply no point in taking risks.

      Thankfully the work done to maintain cooling means that the meltdown may still be averted, and it is also giving people time to evacuate just in case there is a meltdown and a (very unlikely) containment failure.
      • by jeffmeden (135043) on Wednesday March 16, 2011 @02:11PM (#35506604) Homepage Journal

        So there is no risk associated with letting the reactor melt down, and yet they decided to vent radioactive gas anyway? And then, they took the step of using seawater to cool it down despite the fact that the reactor is essentially destroyed after such a corrosive material comes into contact with it, but they "needed" to do that instead of letting it "Safely melt down"? I doubt they trust the reactor shells nearly as much as you do, Mr armchair nuclear engineer.

        • While the GP is downplaying the seriousness of the accident your post does not really make a good argument.

          Nuclear safety usually follows a protocol known as "defense in depth", which pretty much means you don't rely on a single line of defense. Thus even if the containment would be sufficient to contain a meltdown, you'd also do whatever you can to prevent it from reaching that stage in the first place. This may involve venting to release pressure, or cooling with seawater.

          Now obviously there has been a lo

  • The plants are still exploding and threatening to melt down.

  • Really, nuclear power is just exchanging on non-renewable resource for another - radioactive ore for petroleum. I mean, it might not matter if we can eventually mine uranium from space. But the stuff seems pretty rare, out there. Hard to believe that could be as cost effective as, say, building solar panels in space also.
    • By the time we run out of uranium and thorium, we'll have developed fusion power. Or something even better.

      Solar is cost effective in the equatorial deserts of the world, but it won't replace fossil fuels until we have a global superconducting grid. Space PV won't be cost effective (or even implementable) for a long, long time. We need something that can replace fossil fuels *today*. Vast areas are turned into wastelands and thousands of lives are lost every year due to the mining/extraction process. M

    • Uranium is not rare. Uranium is more abundant than Tin. Thorium, another viable nuclear fuel, is even more abundant, and is about as common as Lead. It will take a long, long, long time for us to even come close to depleting those.

  • Just like the Concord was made "less safe" by a single crash on its permanent record. I still wouldn't hesitate to hop on board if it was still in service.

  • by makubesu (1910402) on Monday March 14, 2011 @11:10PM (#35487532)
    we can't allow for a godzilla gap.
  • media and politics (Score:3, Informative)

    by Tom (822) on Tuesday March 15, 2011 @04:33AM (#35488910) Homepage Journal

    I've not changed my opinion on the safety of nuclear technology, in fact the waste disposal still seems to be the bigger problem with the technology.

    However, it has strengthened my view on our (german) politics. Since this week, I honestly believe our government should be in jail and/or shot. Let me explain:

    In 2000, the then government passed a law limiting running times to 32 years for all reactors, which would've put our country at 2021 as the date of the last one being shut down. Most of them would've been offline a lot earlier, as the majority of our 19 nuclear power plants is from the 70s.

    Last year, our current government changed that law, removed the years and replaced them with power generation limits, i.e. each reactor can produce a remainder of X MWh of electrical power before it has to be shut down. Serious calculations now put us at around 2032 until the last one is offline, and some of them will have been running for almost 50 years. In addition, many safety regulations were losened or removed, and remaining power amounts can (under conditions) be transferred between plants. Which means some of them might be running a lot longer/older.

    So our government didn't like their predecessors "out-of-nuclear-energy" plan, but they didn't have the guts to take a stand. We now have some of the oldest, least safe reactors on the planet, and we'll be having them for another 20 years at least.

    My thought on reactor safety: It's a technology that has the potential for catastrophic impact when things go wrong. If you play with safety here for reasons of profit or political power, you are pure evil.

  • by John Pfeiffer (454131) on Tuesday March 15, 2011 @08:00AM (#35489678) Homepage

    I was discussing this on IRC, and someone pretty well summed up my feelings in regard to people saying stuff like "The plants weren't safe enough", etc etc

    "It's like shooting someone in the face with a tank and saying bulletproof vests are useless"

  • by vlm (69642) on Tuesday March 15, 2011 @08:58AM (#35490094)

    I voted seems slightly safer because BWR popcorn was not an issue and that has always been a huge design concern with BWRs.

    I strongly considered going into nuclear engineering, but did not. Anyway one thing I learned in my studies, before I said F it and want into electronics, is BWR design is an unholy PITA because of this scenario:
    Chugging along at full power, something happens, for example, one of the strongest earthquakes in recorded history.
    Steam valves to the turbines shut off. Wham.
    Now a normal BWR reactor runs a void coefficient of like 15%. That means 85% of the core has yummy water moderator and 15% has (more or less) no moderator just steam which makes that bit of the core quite non-reactive. Mixing is very important to prevent fluid boiling and literal oscillation under normal conditions.
    Suddenly, with no place to go because the valves slammed shut, the pressure spikes. That collapses all the steam bubbles and you now have a void coefficient of ZERO.
    That means your moderator effectiveness goes from, perhaps, 85% to 100%. Meaning a huge spike in reactivity. Now a reaction in the center of a fuel rod takes a heck of a lot of time to thermally conduct to the surface, so the reactor has an insane power spike before enough water can boil to shut down the reaction.
    Eventually the thermal heat from the insane spike either vaporizes the fuel rods and literally blows them to bits, or conducts heat into the coolant making the worlds biggest steam explosion. Either way, "BWR popcorn" little bits of reactor all over the countryside about one or two seconds after the steam valves slam shut. Its not entirely like what happens when a old fashioned american tank style water heater blows up, except about a thousand times bigger, sorta.

    Now there are numerous safety features to work around this. Staggering amounts of fluid dynamics and thermodynamics and strange hydraulic things and computer automation to prevent this. Control rods that slam in place faster than the steam valves can shut. Crazy condensation/ventilation systems. Exotic coolant pumps to control circulation. I know the Japanese have a fondness for BWRs and when I heard none of the BWRs popped like a popcorn kernel a few seconds after the quake, I figured they were home free.

    The current crisis is "just another decay heat meltdown" combined with plenty of flaming zirconium fun. Could happen at any ole reactor, PWR, BWR, any fission reactor without coolant. Zirconium is a really great fuel rod cladding from a nuclear properties standpoint, but when it gets hot and water hits it, it acts exactly like sodium, hot hydrogen gas is generated and that pops the pressure relief valves, collects "somewhere" and goes boom. Maybe after this fun we'll switch to something a bit less reactive even if it is less efficient. Kind of like graphite is a really awesome moderator other than that pesky "fire" phenomena (and having to anneal it, which lead to a nice fire in the UK in the 60s, long before Chernobyl)

    Its strange but true, that once you react and literally blow up all the zirconium, assuming the containment vessel holds, which it almost certainly will, all the excitement is over. The goal is numerous small zirconium hydrogen explosions that are all individually too small to crack the containment, not one big ole whopper that cracks it open.

    • by blair1q (305137)

      I don't get why they let it explode.

      All they have to do is leave a pilot light on when they vent it, and it'll burn like a torch instead of explosively. Provided they can get a pilot light to work in that case.

      And if it's got a chance of exploding, why not just vent it to the air? It's going to end up there anyway, when it explodes.

      What really blows my mind is the incredibly stupid cooling-system design that depends on another vulnerable system, the generators, to run. Gravity-fed or steam-driven would se

  • by DarthVain (724186) on Tuesday March 15, 2011 @10:05AM (#35490990)

    The media has been horrible, at least in Canada and the US. They seem to only be able to sell stories and get ratings by trying to scare people. If you look at various other outlets, you see very different reports of what is actually going on, and what the situation is.

    I was totally disgusted that the CBC up here in Canada last night aired a program that was sensationalistic to begin with, and then on top of that brought in an "expert" to comment about want was happening to the power station in Japan. The "expert" was the head of an anti-nuke lobby. Seriously. Unbelievable. That's some responsible balanced coverage let me tell you.

Advertising is a valuable economic factor because it is the cheapest way of selling goods, particularly if the goods are worthless. -- Sinclair Lewis

 



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