Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Nuclear waste waste

  1. Aug 25, 2010 #1
    Nuclear waste should be an oxymoron, or very nearly so at least. I have some questions here for the professionals on line, but I prefix them with remarks intended partly to give some indication of the level of information that I am requesting, and partly to inform amateurs who might see fit to join in the discussion.
    In my opinion, burial or other "disposal" in any form that renders so-called nuclear waste unavailable for practical and profitable future use should be listed as a crime against the planet. Paranoid over-expenditure on eternal repositories is not much better, nor is eternal filibustering to delay and increase the expense of new nuclear facilities. Certainly decent and responsible engineering standards of economy, effectiveness, and safety should be observed, with criminal sanctions against incompetent or malicious violation. Sites such as Hanford (and I am sure that there are others as bad in other countries) are national disgraces, whether they are the product of industrial, mining, or military activities. But that does not mean that sabotage of due process by ill-informed or ill-intentioned persons for purposes of spite or self gratification need be given special consideration as a social virtue.
    In particular, let us consider nuclear "waste". The subject is more complex than most amateurs realise, and I strongly recommend that nonprofessionals who wish to refute the content of this note, first consult some of the excellent material to be found on Google. Particularly convenient discussions appear in Wikipedia, as often is the case.
    Still, roughly speaking, we have low- intermediate- and high-level wastes. I only mention low-level wastes for completeness; much of it is not radioactive at all and the standards of radioactivity in the rest commonly are so restrictive that it tediously leads to embarrassing incidents, such as when visitors to nuclear plants are not permitted to leave, because it turns out that they are too radioactive to leave and should never have been allowed access to the nice clean plant in the first place, in their disgusting state of contamination. Low-level wastes commonly are no more than ordinary wastes that are segregated in case they happen to contain some traces of radioactive material. The main problem with them is their enormous volume. My personal view, which I do not stop to argue or justify, is that such wastes should be converted or disposed of in the most compact and convenient form practical, and forgotten.
    Contrary to what most people think, intermediate-level waste is not a lot worse than low-level waste and can generally be safely handled. It certainly needs responsible attention, and in my opinion (which is too vague to discuss here in detail) there should be more attention given to research into economical and harmless methods of segregating, compacting and dealing with such wastes.
    Recently I visited the South African nuclear waste repository at Vaalputs, which incidentally is a remarkable de facto nature reserve in a very nearly desert area (and I mean very, very nearly!) You have never seen anything so side-of-the-Angels. So far, as far as I know, but I do not vouch for it, it contains only low-level wastes. The serious stuff, old fuel and that sort of thing, is still kept at the power station at Koeberg, which incidentally is a remarkable de facto nature reserve in an arid area with not only fine Spring flower shows, but terrific biology and marvellous fishing near the cooling water outlets. The greenies who went into paroxysms about the effect on wildlife, especially marine wildlife, were badly let down by all the organisms who were extremely grateful for the warm water in our icy Benguela current.
    Anyway, I think that the Vaalputs repository is a boondoggle, and the on-site storage of high-level waste should be giving some authorities to think furiously.
    Okay, that was what I was not interested in saying, much. It was the introductory bit. I'll break off here and start talking about my main point, which deals with high-level wastes, in a separate message.
    Continued in next bottle...
     
  2. jcsd
  3. Aug 25, 2010 #2
    Never heard of this unless the person had a medical procedure involving radioactive isotopes.

    I thought this is what already happens. Most anti-contamination clothing is designed to disolve completely in a chemical bath. The chemicals can be filtered and reused. The only radioactivity that remains is in the filter (demineralizer resins?). Other anti-contamination clothing is laundered and returned to the power plant. I think other low level waste (gloves, rags, etc) can be incinerated and compacted.
     
  4. Aug 25, 2010 #3
    I believe that most serious designs for nuclear waste repositories usually include features to allow the 'waste' to be accessed if/when it is desirable for reprocessing.

    Nuclear waste is politically troublesome because many people fear it, even though it can be stored safely mid-to-long term (many decades) at the NPP people insist on a permanent solution NOW. After all, nuclear waste is seen by the public as very scary stuff -even source material for potential weapons (both dirty or nuclear).

    Take this example from Canada. A nuclear power plant here was recently refurbished including replacement of 16 steam generators. The operator of the plant wants to ship the steam generators to Sweden for recycling to concentrate the radiative material for return to Canada and sell the rest as scrap. The dose rate from the steam generators is very low, the news paper quoted it as it would take more than an hour at 1 m to get the equivalent dose of a single chest x-ray. More than 50 environmental and political groups have been raising hell about this because the plan involves shipping the generators through the Great Lakes water ways. The ends of these steam generators has been welded shut, they have very low activity and the company is making an effort to be transparent but people are still fighting it. I think it is absolutely ridiculous but it is because people fear the term radioactive.
     
  5. Aug 25, 2010 #4

    russ_watters

    User Avatar

    Staff: Mentor

    I doubt it is very common, but that's roughly how the radon issue was discovered:
    http://www.asbestos.com/power-plants/limerick-nuclear-generating-station.php [Broken]
     
    Last edited by a moderator: May 4, 2017
  6. Aug 26, 2010 #5
    I used to live next to the limerick plant, grew up there, and a few years ago did some work for them at both the limerick and peach bottom plants.

    That part of PA has a big radon problem, and if he owned the home long enough he probably never check the levels.
     
  7. Aug 26, 2010 #6

    russ_watters

    User Avatar

    Staff: Mentor

    That's the point: no one checked the radon levels in their home until that guy was found to be radioactive.

    ...and I currently live next to the plant!
     
  8. Aug 26, 2010 #7
    Holo, just reading your response makes me want to gibber and screeeam!!! Not because I disagree, but because of where you are right.
    That is true for chambers, mines and the like where they don't make it inaccessible by closing everything up, nor vitrification and Synroc that make it at the least very difficult to access the material chemically. All the "permanent" solutions I have seen (and some of the stopgaps) seem aimed at effectively total unavailability.

    Right. Which is one of the maddening factors. Most of the public are so ill-informed, not even having bothered to become poorly informed, that they assume that microwave radiation is the same as nuclear radiation (I kid you not!) and that NMR has had to be renamed MRI because J. Public didn't want anything to do with Nukes! <gbberrrr!!!>

    Right. Read "The Invisible Gorilla" by Chabris & Simons. It is not encouraging, but it is enlightening. (Good reading too, incidentally!)
    Cheers,
    Jon
     
  9. Aug 26, 2010 #8
    Uh... Russ? Do I misunderstand your intention? If so, forgive: I plead in extenuation that your wording is confusing. You do realise, I assume, that the source of the radon has nothing to do with the plant?:confused:

    Sorry!

    Jon
     
  10. Aug 26, 2010 #9
    The first part of my discussion of high-level wastes is the main theme of my intention this thread. In particular I should like to know from those best informed, firstly in what ways my suggestions are unpractical, and secondly, if they have merit, why so much public and official attention is concentrated on what seem to me insane measures such as Synroc and vitrification, not to mention subduction burial, deep space disposal, and all the other little sillinesses.

    Seems to me that there are multiple types of high-level waste, and that they deserve different types of attention. I shall have to generalise wildly in discussing them and I request that you avoid chasing some of the irritating details that are at most correct only in particular contexts. I shall ignore for most purposes, isotopes with half lives of well under a year, not because they don't matter, but because if they are a problem, it can be dealt with by storing them for just a few years. In theory they could be of value as sources of energy, mainly in "spent" fuel, but I get the impression that there is little interest. Whether future generations regard this as a triviality, or the nuclear equivalent of "flaring off" unwanted petroleum gases, I am not prepared to guess at the moment.
    In theory there are of course other possible uses for such isotopes, but I also shall not guess how often their extraction might be worth while, or in which quantities.

    Slightly longer lived isotopes, in the range of decades, have a somewhat different relevance. (Special cases such as tritium, that have particular importance in particular roles, I largely ignore as well. ) However such isotopes as say strontium 90, are sufficiently long lived, and sufficiently useful to be worth extraction in many cases.

    So, here is one proposal: any reasonably extractable isotope (radioactive or not) should be regarded as a resource, and not discarded for political convenience. This might apply in some senses to isotopes present in recently retired fuel, but also to isotopes that accumulate in stored radioactive material. Such detailed decisions I do not mind leaving to the responsible engineers. (Nice of me!)

    There are of course other sources than "spent" fuel, such as commercial or medical irradiation sources, some of them categorised as high-level, but as far as I can tell, they are on too small a scale for separate discussion here.

    It does not often count as high-level waste, but another troublesome class includes mine tailings and certain industrial wastes. I fully agree that all such items deserve intelligent and responsible treatment and precautions (broad-minded, aren't I?) However, much the same applies to tailings from various metal and coal mines, not to mention other minerals such as various clays and asbestos. Now, only about 1500 km from where I live, there happen to be a dwindling number of iconic mine dumps that have been a source of mixed pride and revulsion since before I was born. Nowadays many people are complaining about the disappearance. Most of the dumps contain the slimes from treatment of gold ore, and a couple of decades ago some naive mining chemist pointed out that most of them, especially the very old ones, contained more gold than much of the or currently being mined. Since then, their contents being already conveniently ground and above ground, they have been reprocessed with religious dedication.

    So? Well, so as I see it, suitably stored tailings that today are of no obvious value, and considerable obvious danger to soil water etc, if kept in a safe state, might well be expected to be of unforeseen but considerable value to future generations. Even in their original, un-mined state, many of them presented considerable risks to people farming above them, or dependent on water from below them. To assail responsible mining companies (on the laughable assumption that such exist) for mining valuable resources and removing looming threats, is emphatically unethical.

    Right. End of bottle. In the next bottle, I shall discuss "spent" fuel, the big one.

    Cheers for now,

    Jon
     
  11. Aug 26, 2010 #10
    Well then, here is the main message bottle at last! Here I concentrate on spent nuclear fuel and a few related concepts. For decades I read various proposals to dispose of such fuel permanently. Every single proposal encountered objections, often perfectly reasonable objections. Vitrified wastes cracked and dissolved, burial sites oozed and exhaled unspeakable things. Shooting radioactive waste into space was a guarantee of accidentally wiping out cities. Sinking it into clay or abyssal ooze was leaky. Burial into subduction zones was expensive and uncertain. There was no way to be certain that what we buried today would not return to plague our descendants (if any) in perhaps 100,000 or 100 million years.

    Now, the reason most of those were so open to criticism was that they were uniformly hen-witted. Apart from practical problems of disposal and hypothetical problems of what would happen to our seed in the third thousandth or fourth millionth generation, what we were trying to dispose of firstly was not disposable, and secondly could more safely, competently, and rationally be disposed of by using it. As things stand one major reason that the materials are hazardous is largely that they have not yet been used up! Another is that trying to achieve irrelevantly “permanent” storage for something that is not permanent and can safely be dealt with on a comparatively modest time scale is counterproductive in terms of safety as well as practicality.

    Consider: apart from valuable material that is not of much use as fuel, the bulk of the fuel still is present in "spent" fuel. To waste it is criminal. Secondly in most typical modern fuel, the content of fissionable material that is not regarded as fuel is far higher than the original so-called fuel. I will not insult the forum by going into details, but just think of the ratio of power that could still be extracted, either in breeder reactors, or different fuel cycles. If you go surfing for reactor options, the range of designs is bewildering, as are the options for applying waste neutrons.
    We are now urged to burn our fissionable fuels, partly because burning fossil hydrocarbons makes about as much sense as burning banknotes, partly because the supply of hydrocarbons is finite, and partly because burning them creates poisons, allegedly both to humans and the planet. Fissionable fuels in contrast, are an inexhaustible source of power.

    Right?

    Well actually you know the answer to that don't you? If we look at uranium 235, the supply is shockingly small, especially since we burn only a modest proportion of it. The supply of uranium 238 is a lot better, though far from satisfactory. Thorium is better still, though our interest in thorium burning is still faltering. But none of these is so plentiful that we can afford to waste them. People are speaking of supplies adequate for hundreds or thousands of years; that is a blink, not a prospect! On even the most optimistic estimates we bid fair to burn all our carbon fuels in a few centuries, and we hardly started doing that two centuries ago!

    We need every joule we can get out of our fuel, and all the valuable material that we can get as well. The same people who demand that we waste more than 90% of our fissionable fuel in the form of useless, dangerous residues would be horrified at the suggestion that we do the same with all our coal by burning it uselessly in the open or for that matter in underground fires, but the proposed incompetent disposal of nuclear fuel seems to be just what they want.

    There is no prospect of immediate replacement of current nuclear power technologies or infrastructures, and in fact there is no foreseeable prospect of fission power without fuel recycling. The question then reduces to what to do with the fuel between one cycle and the next.
    There are many considerations. Suppose that we immediately and infallibly treat all spent fuel as soon as it can be handled by the most convenient technology. This would only be desirable if we could use the products quite soon, since radioactive decay continues even in the absence of criticality, and many of the products are undesirable in the fuel material. Secondly, justifiably or not, there is considerable concern for nuclear security. Processed fuel is far more valuable, and easier to steal and dangerous, than unprocessed, which is harder for unauthorised people to handle and process. It follows that most rational approaches would delay fuel recycling to the last practical time.

    What to do with the spent fuel in the meantime? There are two approaches. One would be to keep it in standard, high security, stores, unprocessed until it is needed. Suitable protocols should defend it from inimical parties and protect the health of the public as well. One principle would be to seal them in large, heavy containers that only could be moved and opened slowly with special equipment and moved with special, large, slow vehicles. Call these nuclear ashcans. The containers would be self-contained and sealed to contain volatiles. They would not have to last forever, and they could be kept anywhere secure, irrespective of earthquake, fire, flood or aircraft crashes. Only war and large meteorites could threaten them, or perhaps other events of such a nature that breaching of the ashcans would seem like a minor nuisance in comparison. They could not be used as dirty (conventional) bomb materials, would be re-usable, and if decently designed, should be a fraction of the price of long-term storage proposals.

    Details of ashcan designs and protocols for handling them should be fun to design, but not of immediate concern here.

    An alternative, probably to be used in combination with the ashcans, would be a range of reactors in which spent fuel could surround the main core, to be irradiated by waste neutrons of a suitable spectrum of energies, either for breeding, or transmuting unwanted isotopes until the resultant state suited the reprocessing requirements. Anyone stealing anything from such a repository had better be heatproof, neutron-proof, and proof against ionising radiation. Again, access should require special equipment and permit only slow, monitored removal with the cooperation of multiple authorised personnel.

    In sum:
    We need to keep our nuclear fuel in all its forms till it has been utilised to the full.
    We need to use the products (isotopes mainly) to the full.
    We should not waste money or require special locations for long-term storage. Storage on the scale of decades instead of millennia should be quite adequate.
    No fancy immobilisation, vitrification or similar technologies need be developed.

    Any comments?

    Jon
     
  12. Aug 26, 2010 #11

    mheslep

    User Avatar
    Gold Member

    The reserves of Uranium 238 are very satisfactory.

    [PLAIN]http://www.klydon.co.za/images/Depleted_Uranium.jpg [Broken]
     
    Last edited by a moderator: May 4, 2017
  13. Aug 26, 2010 #12

    Astronuc

    User Avatar
    Staff Emeritus
    Science Advisor

    Well that's easy to say, but it's expensive to practice.

    Spent fuel (from an LWR) has reached it's useful life in that LWR. The fission products have accumulated such that the U-235 and Pu-239 cannot be effectively used. The cladding and structural members are oxidized and hydrided to preclude reliable operation, and rod internal pressure may be approaching a threshold where fuel rod hermeticity is challenged or compromised under normal operating conditions, anticipated operational occurrences (AOOs) or postulated accidents.

    Sure one can reprocess the spent fuel, but that requires a chemical processing plants, which is a huge liability, not to mention cost to the operator. That's why the government has traditionally performed and controlled that activity, although the vendors did perform some of the activities in the 70's.

    Most proponents of reprocessing expect that there would be a centralized facility for receiving, reprocessing the spent fuel, recycling of fuel materials, fabricating new fuel, and disposing of fission product waste. One factor with respect to reprocessed (Pu-bearing) and recycled fuel is the radioactivity, which then necessitates remote handling and remote inspection. It's not as simple as one might imagine.
     
  14. Aug 30, 2010 #13
    That is for now. For now, even our oil reserves are satisfactory; not compared to 50 years ago, but at least we can get as much as we like any time we like. All we have to do is dig down for kilometres, far below the ocean... etc.
    I wold have found your (very striking) pic more reassuring if I had not seen the huge amounts of hydrocarbon fuels we gobble daily, and some of the figures for how fast we would need to burn U238 et al. just to keep up with our current consumption. Guess how fast our fuel demands are slowing down?
     
  15. Aug 30, 2010 #14
    OK, did anyone suggest that less wasteful practices came free? If they did, no one would bother to avoid their use. The question is whether the fuel that some parties want to waste in their permanent sequestration schemes can be used at an energetic profit. As long as there is more energy to be got by burning it than dumping it, then it should not be dumped. If you think that burning it will raise the price of power, just wait till you see what dumping does to the price!

    No quarrel. The details I am certain, will vary with the nature of the fuel and the fuel assemblies and the fuel cycle. I am not suggesting that every kind of item could be retained just anywhere forever. In engineering everything is subject to objectives and practicality. You know that for sure!

    Liability? I suppose you could put it that way. I would rather have called it part of the cost of doing business. Are we at cross purposes?

    I don't much mind who does it, as long as it gets done safely and efficiently. After all, I am one of the guys who pays in the end.

    Well, once again, who could possibly have thought it simple or cheap? If it means more power, less waste, and less long-term risk, then that is the way to go, no?
    And when still better ways emerge, with different (hopefully smaller) overheads, then we change again...
    Progress and all that!

    Cheers,

    Jon
     
  16. Aug 30, 2010 #15

    mheslep

    User Avatar
    Gold Member

    In the case of U238 or Thorium, now is several thousand years.

    Consider that the energy density of nuclear fuel is roughly one million times that of chemical fuels, then that U238 storage photo above truly is striking.

    Lately in the US consumption has been slowing down about 4% per year.
    http://tonto.eia.doe.gov/dnav/pet/pet_cons_psup_dc_nus_mbblpd_a.htm
    Further into the future for the US oil consumption is forecast as flat, with a growing economy roughly offsetting increasing efficiency.
     
    Last edited: Aug 30, 2010
  17. Sep 1, 2010 #16
    Yes? And?
    For a start, how much U238, let alone any isotope of thorium, are we using now? Last time I looked it was mainly U235 plus some plutonium. A lot of people are getting very upset at the very idea of burning U238, let alone deriving useful fissile material from it.
    And, "several thousand years"?
    Are you serious? If you had said several million, then if I had believed you I might have been favourably impressed, but several thousand years amounts to a blink, hardly longer than our recorded history in any form. If that is the scale we are working on, then we are in serious trouble!


    Certainly. Make no mistake, I was struck! But not dumbstruck. If striking photographs were what it is all about, then there are many photographs that might well reduce a peak oil partisan to a state of gibbering terror.

    Now there is a gobsmacker! Just how far into the future do you suppose you could rationally extrapolate that trend?
    Go well,
    Jon
     
  18. Sep 1, 2010 #17

    mheslep

    User Avatar
    Gold Member

    'We', being those of us currently walking and talking, our descendants, their descendants, and so on a few times over are not in trouble of running out of some kind of nuclear fission fuel.
    The ~flat forecast for US oil consumption is indefinite. For that matter thehttp://en.wikipedia.org/wiki/Energy_intensity" [Broken] of most developed countries is flattening out.

    1zfmlo8.gif
    http://www.eia.gov/oiaf/aeo/pdf/trend_4.pdf [Broken]
     
    Last edited by a moderator: May 4, 2017
  19. Sep 2, 2010 #18
    Get real! Is that really your criterion for justification of waste? I thought that attitude had gone out with the Victorians.
    Apart from anything else, in that comment you do not distinguish between fission of U235, thorium and uranium 238. What is your estimate for our future if the nuclear energy Nazis were to succeed in preventing the use of anything but U235? (Hint: think 0.7% as an overoptimistic assessment!)

    Please note that nothing that you say in that assertion, even if your most optimistic assumptions were true, would change the situation that I describe any more than slightly and quantitatively. I hope it is becoming plain that in key respects we are at cross purposes. You essentially are saying: "there is nothing to worry about; we have fissionables for a long time yet."
    I, in turn, have permitted myself to be side-tracked into saying: "there is plenty to worry about, what you call a long time is horrifyingly short."
    What I started out by saying was the more fundamental point that:
    1: fissionables are finite resources and not easily renewable
    2: the most convenient fissionables (mainly U235) are locally in short supply in nature
    3: less convenient fissionables, whether occurring in nature or as by-products of nuclear power plants, are available in far larger, but still finite amounts
    4: to waste those fissionables, whether through inefficiency or refusal to use them constructively, is gross irresponsibility.
    Okay.
    Okay?
    Does that put us more nearly onto the same page?
    Please let me know.
    Cheers,
    Jon
     
    Last edited by a moderator: May 4, 2017
  20. Sep 2, 2010 #19

    mheslep

    User Avatar
    Gold Member

    Wasted? Yes some U235 and Pu is left in spent fuel rods in once through cycle countries, requiring a process to recover it, but its not wasted in the 'destroyed' sense. Aside from U235/Pu that's undergone fission to produce energy or decayed naturally, U235 is not going anywhere.
     
  21. Sep 3, 2010 #20
    If it is deeply buried in synrock or inaccessible repositories, it doesn't need to go anywhere; it has largely gone. If it is in wells dug into subduction zones it certainly does go somewhere: away! In neither case does it need to be "destroyed" to be wasted.
    For purposes of public safety, no such wastage is necessary. Simple, secure, accessible storage would be quite enough protection without going crazy about making anything go away forever.
    And the amount of usable fissionables remaining in fuel rods is not just "some". It is the greater part by far. For a start, commercial enriched fuel is not 100% U235, remember? More like 3% to 6%. The rest is mainly U238 and isotopes of Pu, and much of it is neither burned nor even converted on that pass through most current LWRs etc.
    Secondly, the reason for removal of fuel from a reactor is usually mainly that it is full of poisons that absorb neutrons, not shortage of fissionable material. To dump such fuel in any form whatever, such that it cannot be retrieved, is the crime that I referred to: the wastage of usably fissionable fuels.
    Are we getting closer?
    CU,
    Jon
     
  22. Sep 3, 2010 #21

    mheslep

    User Avatar
    Gold Member

    I'm aware of synrock proposals, but where is this done today? Not in the US on any scale. Do you have a source?

    We're talking about just fissionable U235 at this point, merely fertile U238 up thread, and U235 achieves about 3/4 burnup in LWRs.
    http://www.ricin.com/nuke/gifs/burnup.gif

    What are you talking about? This doesn't occur on any scale, at least not in the US. And BTW, I suggest there is virtually no place waste can be safely dumped where it can not also be retrieved given sufficient resource. That being the case, only effort is wasted, not matter.
     
    Last edited by a moderator: Apr 25, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook