Perceptions of nuclear risks

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  • If I'm lucky, Dr. Cresswell might give this summary a B-.
    Yeah, B- seems sound.

    Power reactors don't usually enrich as much a 4-5%, 2-3% is more common (some designs use natural uranium, avoiding the enrichment step altogether). In some cases rather than enrich in 235U fuel is produced by mixing in a small quantity of 239Pu - which is called MOX (Mixed OXide). Small reactors need highly enriched fuel, neutrons are lost too readily to maintain a chain reaction without the higher enrichment. Just before I started work here there was a spare set of fuel plates in a cupboard for our research reactor, at 95% enrichment. The other small reactors that use such fuel are for marine applications (submarines and surface vessels) which need to fit into very confined spaces.

    239Pu production still has some sticky steps, you can't just put 238U in a reactor and then separate it out chemically. Too short a time in the reactor and you don't get much 239Pu, leave it in there too long and you make 240Pu and 241Pu which you can't remove by centrifuge (the mass difference is too small) and have a high cross-section for neutron capture without fissioning ... have too much of these and your bomb is a bit of a fizzle (this was also a concern for the Nagasaki bomb, a more complex design requirement and an unknown tolerance for heavy Pu contaminants).
  • The longer a long-term view one takes of our planet the better clean renewables look
  • Merry Vole wrote: »
    The longer a long-term view one takes of our planet the better clean renewables look

    They won't get us through the next ice age maximum!
  • At present, we're heading towards never experiencing a glacial maximum again.

    But, even if we were on a natural cycle there'd still be a few millennia before then, and the only choice we make about low-carbon energy we'll make now that would have any impact over that time scale is nuclear - because there would still be a need to maintain safe storage for the waste generated.
  • sorry, being a vole of very little brain I don't understand the connection with the need for nuclear and the need for safe storage of waste..
  • But that's not a problem is it? Storage? And the thought that our 1% affect on temperature even for 10,000 years ahead would counter the Milankovitch cycles in the 100,000 years we can easily expect as a species is a tad... fanciful?
  • Merry Vole wrote: »
    sorry, being a vole of very little brain I don't understand the connection with the need for nuclear and the need for safe storage of waste..
    It's relatively simple. Nuclear power inevitably produces highly radioactive waste materials, and so safe nuclear power also needs to include safe storage of that waste material - and, that material will need to be kept safe for thousands of years. Despite decades of research, there's still no agreed option for how to store the waste we've already generated over that time scale, much less how to expand the options for a massive increase in the use of nuclear power. We have a viable interim solution, there's no real problem with storing spent fuel at the site of nuclear power stations during the century or so that it'll take to decommission the site. But, should we be generating more waste now in the expectation that we have a century or more to sort out a long term storage solution?
  • Martin54Martin54 Shipmate
    edited October 2020
    There's no real problem is there? 'In 2010, it was estimated that about 250,000 t of nuclear HLW were stored globally' (WFW - Wah Friend Wiki). Vitrification (assuming that isn't post-vitrification, which it probably is?) will increase the mass by an order of magnitude and the volume to, what, 3 t m^3, so, ooooooh (here we go again) 2,500,000 t > 1,000 m^3 to date. A tenth of a cricket field a meter deep. Assuming an order of magnitude more, call it two for every century for the next ten thousand years = 10 cricket fields a century = 1000 cricket fields. One hard rock multi-level mine in Sweden or Finland or Canada or the US or Russia or Antarctica could easily take that. What's the problem?
  • Transporting from A to B safely in an unstable world.
  • The first problem is that no one has answered the question of whether simply burying things in the ground and forgetting about them is the best option. A typical reactor produces 25t of HLW per year, so let's call that 1,000t over the lifetime of the reactor (40y). There are currently about 500 reactors in operation or under construction. So that's at least 500,000t of HLW. Plus the 250,000t from reactors that have closed. Let's call it a round million even without starting construction on any more reactors. That fuel is (literally) too hot to handle for 5-10y after it's removed from the reactor. Thereafter it becomes possible to move it into some form of interim storage - it's still hot enough to need to be actively cooled and monitored (all of which takes electricity that needs to be generated from somewhere) for something like 50-100 years. It's only at that point that it's cooled down enough that it's even possible to consider long term storage - and, the technology for that is totally unproven. We can vitrify material, but we don't know how that glass will behave for long storage (we have some experimental vitrified material monitored for 10-20 years, which gives us a reasonable extrapolation for a 100 years or so ...). How do you ensure that a deep, sealed store doesn't leak over millennia? Or, do you make the store retrievable, so that if there's a problem you can remove the waste and put it somewhere better?

    And, of course, this assumes this material is actually waste. A couple of years ago we had a student do some work calculating how much rare earth metals would be present in these materials ... the answer is more than present in ore grade deposits that are commercially mined. These are some of the most valuable materials on earth, essential to many modern devices (including batteries), do we really want to put them out of use forever? The PhD student currently attached to our group is looking at the heat produced by this material, and whether it can be harnessed for beneficial purposes - which, again, needs these stores to be accessible in some manner.
  • Martin54Martin54 Shipmate
    edited October 2020
    Absolutely, worth a fortune once the economies of scale kick in. And aye, I'm aware of the cooling pools. Wouldn't the heat generate electricity from somewhere ; ) Aren't there natural fossil reactors in Gabon which should tell us what happens to leaking vitreous, ceramic, petrified 'waste'? Not geologically current I realise. What's happening underneath the Chernobyl corium? I'd be surprised if you guys hadn't exposed vitreous ceramics to orders of magnitude more intense neutron, proton, electron, positron and gamma bombardment. What happens? And would would have to assume leakage, what could happen?
  • One...
  • Martin54 wrote: »
    But that's not a problem is it? Storage? And the thought that our 1% affect on temperature even for 10,000 years ahead would counter the Milankovitch cycles in the 100,000 years we can easily expect as a species is a tad... fanciful?
    1%?

    We've raised the temp above pre-industrial by a Celsius already.
  • And a Kelvin.
  • Transporting from A to B safely in an unstable world.

    Unstable in what regard? Trains crash, ships sink, so? Is there any other unquantifiably remote risk?
  • Martin54 wrote: »
    Merry Vole wrote: »
    The longer a long-term view one takes of our planet the better clean renewables look

    They won't get us through the next ice age maximum!

    The wind and the sun cease during an ice age?
  • Merry Vole wrote: »
    Martin54 wrote: »
    Merry Vole wrote: »
    The longer a long-term view one takes of our planet the better clean renewables look

    They won't get us through the next ice age maximum!

    The wind and the sun cease during an ice age?

    It snows a bit. During the last one Glasgow was under a mile of ice.
  • Martin54 wrote: »
    But that's not a problem is it? Storage? And the thought that our 1% affect on temperature even for 10,000 years ahead would counter the Milankovitch cycles in the 100,000 years we can easily expect as a species is a tad... fanciful?

    OK, alarmist.
  • Martin54Martin54 Shipmate
    edited October 2020
    Martin54 wrote: »
    Merry Vole wrote: »
    Martin54 wrote: »
    Merry Vole wrote: »
    The longer a long-term view one takes of our planet the better clean renewables look

    They won't get us through the next ice age maximum!

    The wind and the sun cease during an ice age?

    It snows a bit. During the last one Glasgow was under a mile of ice.

    We're in an ice age now of course, as there is still ice at the poles, the last glacial maximum was: 'According to Clark et al., growth of ice sheets commenced 33,000 years ago and maximum coverage was between 26,500 years and 19–20,000 years ago'.
  • Poking the lion through the cage again (and getting in your notifications):
    At present, we're heading towards never experiencing a glacial maximum again.

    But, even if we were on a natural cycle there'd still be a few millennia before then, and the only choice we make about low-carbon energy we'll make now that would have any impact over that time scale is nuclear - because there would still be a need to maintain safe storage for the waste generated.

    That 'because' itches.
    Martin54 wrote: »
    But that's not a problem is it? Storage? And the thought that our 1% affect on temperature even for 10,000 years ahead would counter the Milankovitch cycles in the 100,000 years we can easily expect as a species is a tad... fanciful?

    Which I later sharpened up from the euphemism with 'OK, alarmist.'.

    The stream moved on with your unquestionable, rightly abundantly cautious exposition of the issues of storage, with the silver lining of benefit, and my Martini bet a nickel questioning nonetheless followed.

    A certain Mr. Clingford then had the temerity to question me!
    1%?

    We've raised the temp above pre-industrial by a Celsius already.

    To which I said 'And a Kelvin.' as the % change is over the absolute temperature scale and we're not even half way to 1% up on pre-industrial.
  • Martin54 wrote: »
    Poking the lion through the cage again (and getting in your notifications):
    At present, we're heading towards never experiencing a glacial maximum again.

    But, even if we were on a natural cycle there'd still be a few millennia before then, and the only choice we make about low-carbon energy we'll make now that would have any impact over that time scale is nuclear - because there would still be a need to maintain safe storage for the waste generated.

    That 'because' itches.
    Martin54 wrote: »
    But that's not a problem is it? Storage? And the thought that our 1% affect on temperature even for 10,000 years ahead would counter the Milankovitch cycles in the 100,000 years we can easily expect as a species is a tad... fanciful?

    Which I later sharpened up from the euphemism with 'OK, alarmist.'.

    The stream moved on with your unquestionable, rightly abundantly cautious exposition of the issues of storage, with the silver lining of benefit, and my Martini bet a nickel questioning nonetheless followed.
    I'm unclear whether there's a question there that you want me to answer.

    Storage is a problem, or a potential problem (and, an unknown is still a problem of a different kind) because we don't have a proven means of storing nuclear waste safely on the long timescale needed. We know how to store waste in the interim (the next century, ish) though our implementation of that often leaves something to be desired - on the surface in ponds, which require energy to maintain (so present an additional carbon cost in most places), or in dry form (usually vitrified) which can usually be cooled passively (air intake at the bottom gets heated by the waste and rises up a chimney drawing more air in), in most cases short term water storage before vitrification at present with a massive backlog of old material in ponds. The long term is unclear, we don't have data on how long the glass will last under the heat and radiation it's exposed to, our best analogues are medieval glasses with a few centuries of history which we know flow and deform ... the question is do our vitrified wastes behave in the same way over a few centuries or a century of millennia? An underground store could be preferable in terms of control of the environment the waste is stored in (the surrounding rock providing a large thermal capacity to maintain temperature) providing water ingress can be controlled. But, it's very difficult to maintain an underground facility without water getting in even over a few years much less millennia. A surface store can be kept dry more easily, but is also inherently less secure against climate change or societal change (will future generations be able to monitor and maintain such a store?)

  • Martin54 wrote: »
    To which I said 'And a Kelvin.' as the % change is over the absolute temperature scale and we're not even half way to 1% up on pre-industrial.

    I'm sorry - are you under some kind of bizarre impression that a percentage change on an absolute temperature scale is a useful metric for quantifying climate change?
  • Martin54 wrote: »
    To which I said 'And a Kelvin.' as the % change is over the absolute temperature scale and we're not even half way to 1% up on pre-industrial.

    I'm sorry - are you under some kind of bizarre impression that a percentage change on an absolute temperature scale is a useful metric for quantifying climate change?

    Why would I be?
  • Martin54 wrote: »
    Martin54 wrote: »
    To which I said 'And a Kelvin.' as the % change is over the absolute temperature scale and we're not even half way to 1% up on pre-industrial.

    I'm sorry - are you under some kind of bizarre impression that a percentage change on an absolute temperature scale is a useful metric for quantifying climate change?

    Why would I be?

    Because you dragged it into the thread.
  • Martin54 wrote: »
    Poking the lion through the cage again (and getting in your notifications):
    At present, we're heading towards never experiencing a glacial maximum again.

    But, even if we were on a natural cycle there'd still be a few millennia before then, and the only choice we make about low-carbon energy we'll make now that would have any impact over that time scale is nuclear - because there would still be a need to maintain safe storage for the waste generated.

    That 'because' itches.
    Martin54 wrote: »
    But that's not a problem is it? Storage? And the thought that our 1% affect on temperature even for 10,000 years ahead would counter the Milankovitch cycles in the 100,000 years we can easily expect as a species is a tad... fanciful?

    Which I later sharpened up from the euphemism with 'OK, alarmist.'.

    The stream moved on with your unquestionable, rightly abundantly cautious exposition of the issues of storage, with the silver lining of benefit, and my Martini bet a nickel questioning nonetheless followed.
    I'm unclear whether there's a question there that you want me to answer.

    Storage is a problem, or a potential problem (and, an unknown is still a problem of a different kind) because we don't have a proven means of storing nuclear waste safely on the long timescale needed. We know how to store waste in the interim (the next century, ish) though our implementation of that often leaves something to be desired - on the surface in ponds, which require energy to maintain (so present an additional carbon cost in most places), or in dry form (usually vitrified) which can usually be cooled passively (air intake at the bottom gets heated by the waste and rises up a chimney drawing more air in), in most cases short term water storage before vitrification at present with a massive backlog of old material in ponds. The long term is unclear, we don't have data on how long the glass will last under the heat and radiation it's exposed to, our best analogues are medieval glasses with a few centuries of history which we know flow and deform ... the question is do our vitrified wastes behave in the same way over a few centuries or a century of millennia? An underground store could be preferable in terms of control of the environment the waste is stored in (the surrounding rock providing a large thermal capacity to maintain temperature) providing water ingress can be controlled. But, it's very difficult to maintain an underground facility without water getting in even over a few years much less millennia. A surface store can be kept dry more easily, but is also inherently less secure against climate change or societal change (will future generations be able to monitor and maintain such a store?)

    Sorry, OK Alan. Yeah, so there is no reason not to go ahead, not to vitrify. The carbon cost of the ponds, vitrification and storage must be negligible compared with non-nuclear waste. All the, in every way remote, hypotheticals can be addressed if they ever look like arising, which is incalculably unlikely, or if not we're in to Second Sleep and all bets are off anyway.
  • A PhD student I'm helping to supervise is just starting to put together a paper in which she'll quantify the carbon cost of storing nuclear waste - or, rather the energy cost and then the carbon cost under different scenarios; the carbon cost in Scotland will be small because of our majority and growing renewable generating capacity; in France it will be small because of their large nuclear capacity, but only until their reactors are all shut; in the US where over 60% of electricity generation is from fossil fuels (and a quarter of the capacity is coal, the dirtiest of the fossil fuels) the carbon cost will be higher. It's not an inconsiderable amount of energy needed to maintain these stores.

    The present trajectory for waste storage is to vitrify at least the highest activity waste, something like 20-30 years after the fuel has been removed from the reactor. That certainly looks like the most promising approach to secure these materials over the 100-1000y timescale. What we do with these lumps of glass containing high level waste for storage beyond that timescale is an unanswered question, and one that will almost certainly leave our grandchildren pondering what they're going to do with the waste we produced.
  • Fascinating. The more the merrier. But why would France ever shut down all of its nuclear capacity? And again, seriously, the Marianas Trench and/or shield volcanoes?
  • Martin54 wrote: »
    Fascinating. The more the merrier. But why would France ever shut down all of its nuclear capacity? And again, seriously, the Marianas Trench and/or shield volcanoes?

    You want to pollute the deep sea and/or risk a large-scale radiological disaster when said volcano erupts?
  • DafydDafyd Shipmate
    Martin54 wrote: »
    And again, seriously, the Marianas Trench and/or shield volcanoes?
    I wonder why nobody has thought of that before.

  • Martin54 wrote: »
    But why would France ever shut down all of its nuclear capacity?
    You'll probably have to ask the French why they've only one reactor under construction and have a policy to reduce nuclear to 50% of capacity by 2035. Public concerns over safety is one part of the reason. Increasing costs, while wind and solar get cheaper, is another. Lack of a programme for long term storage of waste is another. Basically, the same reasons why the UK is lukewarm about new nuclear.
  • Martin54Martin54 Shipmate
    edited October 2020
    Thanks Sensei. Again. Fascinating. So the brilliant French establishment, who know that safety is a non-issue, are going with - irrational - public concern. Including of storage. I can't believe they are concerned about the fiscals: The tax payer is prepared to sacrifice and 'Qui sommes nous...?'. Same in our brilliant establishment.

    Can Nigeria afford that luxury? I hope so, that is
    if @Arethosemyfeet is right. And they might be.

    ('Who are we...?')
  • To me the obvious solution is deep burial in a non-geologically active area. Nuclear waste is after all not the only hazardous substance in the world - there are other non-nuclear dangerous things that don't even decay over time but remain permanently toxic. Since nuclear waste already exists, surely it must be better to get on with putting it into long-term storage rather than leaving it lying around in short-term storage such as cooling ponds.

    One speculation I have seen is that some of the fission products and associated decay products - various rare-earth elements - could be quite valuable either now or in the future, and that long-term storage should therefore include the possibile of getting the waste back in order to extract these. I don't know whether this really makes sense though.
  • Dafyd wrote: »
    Martin54 wrote: »
    And again, seriously, the Marianas Trench and/or shield volcanoes?
    I wonder why nobody has thought of that before.

    Of course they have, it's the kind of thing you keep in your back pocket. But as @Alan Cresswell initially said & @TurquoiseTastic just above, it will be worth storing. Providing that wind isn't being massively overstated.
  • Martin54 wrote: »
    Dafyd wrote: »
    Martin54 wrote: »
    And again, seriously, the Marianas Trench and/or shield volcanoes?
    I wonder why nobody has thought of that before.

    Of course they have, it's the kind of thing you keep in your back pocket. But as @Alan Cresswell initially said & @TurquoiseTastic just above, it will be worth storing. Providing that wind isn't being massively overstated.

    Irony meter needs recalibrating.

    Martin, try increasing the greys in your view to decrease the black and white.

    But, it's nice to be able to comprehend what you say. I read your posts now. Which might sound a bit passive-aggressive, but isn't meant to be. Damn lack of tone in text!
  • Cool @Mr Clingford. Nuclear power has been blackened for 70 years and environmental alarmism in general is as dark as it gets. They benighted me for 50 years, all part of the same apocalyptic hysteria which pervades this site as it does our culture. Difficult to see it as a monochrome issue. And I'm not whitewashing to the other extreme to 'compensate', for 'balance'. Just shining some evidentiary orthogonal light for critique.

    I'm open to reason about wind power, if @Arethosemyfeet's information pans out. But still see no rational reason whatsoever that the non-WEIRD world will, can, would, could, should not pursue nuclear power. As for the WEIRD world...
  • Martin54 wrote: »
    Dafyd wrote: »
    Martin54 wrote: »
    And again, seriously, the Marianas Trench and/or shield volcanoes?
    I wonder why nobody has thought of that before.

    Of course they have, it's the kind of thing you keep in your back pocket. But as @Alan Cresswell initially said & @TurquoiseTastic just above, it will be worth storing. Providing that wind isn't being massively overstated.

    Not happy with myself there. Losing the stuff in Hawaii would only be worthwhile if it were useless. The more we make, the less useless it will be, we'll find a use for it. I like the idea of wind for hydrogen, but I still can't see how wind as primary, even at 50% efficiency, can cope with peak demand without massive storage infrastructure (reverse, i.e. uphill, hydroelectric?) for trough demand. A mixed nuclear, wind, hydro, hydrogen economy would be optimal?
  • Question re storage: I read James Lovelock's book on Gaia but I have since passed it on. In it he says he has offered to have nuclear waste buried in his own garden because it is so low risk. What's that all about?
  • Short term, nuclear waste can be packaged such that it can be stored safely in small quantities almost anywhere - packaging needs to be sealed such that active materials can't escape, and such packaging will block alpha and beta radiation, and if the quantity is small then the gamma radiation that will penetrate the packaging will be small compared to the natural background - plus if buried below 30cm the soil will block the vast majority of the radiation that is left. So, yes if I had a garden I'd have no problem with a small quantity of properly packaged waste buried there. But, that's short term - the long term problem is that it's impossible to package such material which will ensure that material is safely contained, especially in an uncontrolled environment such as a garden where it will be subject to water, changing temperatures if near the surface, roots of trees, burrowing insects and animals ... or some curious child digging it up in 40 years without knowing what it is.

    The proposals for long term storage in a deep cavern presents the same problems writ large. We can build a dry store, but can't keep it dry over millennia. Building that store creates new routes to underground environments and new ecological niches for various lifeforms. We may be able to put in place schemes to have the entrance guarded for a century or two ... but, we can't plan for next year with certainty, can we be sure that our plans to prevent our curious great(x several times) grand kids from being curious about this hole in the ground and pulling highly radioactive material back to the surface?
  • But don't the same issues exist to a much greater degree with other dangerous objects, man-made or otherwise, strewn around the environment? We can't be sure that curious people in 2000 years time won't fall into old coal-mines or bore-holes, or indeed dig up naturally occurring nuclear material or other toxins and poison themselves with it, can we?
  • Indeed, nuclear waste isn't unique in that sense. Various parts of the world have significant issues with toxic residues from mineral extraction or refinement - lead, mercury, arsenic etc can be as dangerous if ingested. And, some of these problems could be as long lasting. Does that justify adding even more waste onto the problem?
  • We may be able to put in place schemes to have the entrance guarded for a century or two ... but, we can't plan for next year with certainty, can we be sure that our plans to prevent our curious great(x several times) grand kids from being curious about this hole in the ground and pulling highly radioactive material back to the surface?

    ...remembering, of course, that if our ancestors 1000 years ago made a big sign saying "don't come in here, it will kill you", most contemporary people wouldn't be able to read it.
  • We may be able to put in place schemes to have the entrance guarded for a century or two ... but, we can't plan for next year with certainty, can we be sure that our plans to prevent our curious great(x several times) grand kids from being curious about this hole in the ground and pulling highly radioactive material back to the surface?

    ...remembering, of course, that if our ancestors 1000 years ago made a big sign saying "don't come in here, it will kill you", most contemporary people wouldn't be able to read it.

    As I recall, plans for nuclear waste storage included pictures depicting consequences of getting too close, and text in multiple languages providing warnings and asking that if the text was fading it be renewed and if the languages were passing from use they be replaced with contemporary ones.
  • Martin54Martin54 Shipmate
    edited October 2020
    All extremely remote theoretical contingencies. If our descendants are at risk, they will have survived the almost impossible, total, decapitating collapse of civilization killing 95% and more. Why otherwise would we forget?
  • Martin54 wrote: »
    All extremely remote theoretical contingencies. If our descendants are at risk, they will have survived the almost impossible, total, decapitating collapse of civilization killing 95% and more. Why otherwise would we forget?

    Poor record keeping and/or deliberate destruction of records could happen as part of an incompetent regime (say, a future Trump-alike) revolution or natural disaster far short of total collapse. The point is that we simply don't know what will happen in the future, and whether our present information-rich age is a permanent fixture or a temporary and unsustainable blip.
  • Martin54 wrote: »
    All extremely remote theoretical contingencies. If our descendants are at risk, they will have survived the almost impossible, total, decapitating collapse of civilization killing 95% and more. Why otherwise would we forget?

    Poor record keeping and/or deliberate destruction of records could happen as part of an incompetent regime (say, a future Trump-alike) revolution or natural disaster far short of total collapse. The point is that we simply don't know what will happen in the future, and whether our present information-rich age is a permanent fixture or a temporary and unsustainable blip.

    If it's not sustainable, billions will die at the turning point. May be in an afternoon or a year or ten. All bets are off. No reason not to pursue a nuclear backbone economy.
  • Excellent news. Seems that the UK will have a nuclear powered backbone.
  • Sizewell C passed through a few legislative hoops in March, but faced big finance problems in relation to the Chinese stake in the plant and considerable uncertainty about Bradwell (the Chinese design there hasn't progressed through even the first sets of regulatory hurdles relating to the suitability of the generic design - the EPR planned for Sizewell, and being built at Hinckley, has gone through all those steps ... obviously, otherwise construction wouldn't have started). This news looks like the UK government has taken on that Chinese stake in Sizewell, thus removing the big finance hurdle, which is a reversal of previous government policy (we seem to now have a government committed to U-turns). It would mean plans for Bradwell are dead.
  • Martin54Martin54 Shipmate
    edited October 2020
    An open question @Alan Cresswell: as wind can never fulfil demand without massive redundancy of generation and storage (reverse hydro) capacity alone, nuclear as the greenest backbone is essential even in the windiest country in the world. So what is the most rational financing model for nuclear-hydro-wind-hydrogen (solar on all roofs)? It's got to be a level playing field hasn't it? Weighted, if anything, with JFDI: just flamin' do it. There must be a treasury model for this? If not, there's another Ph.D. for you.
  • Concerning storage, is it conceivable that a distributed model with every household having a Tesla battery wall or equivalent could solve the problem of intermittent renewable generation?
  • Concerning storage, is it conceivable that a distributed model with every household having a Tesla battery wall or equivalent could solve the problem of intermittent renewable generation?

    Depending on its capacity, sure. Probably more efficient to have them at neighbourhood or street level, or building level in high rise areas.
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