Perceptions of nuclear risks

2456

Comments

  • So, how do we lobby?
  • Probably more to do with financial risks than any other type of risk, but The new Wylfa nuclear in North Wales is off.
  • edited September 2020
    Economic risks are also behind the on/off plans for Sizewell C (added political complication of the significant contribution from China).
  • As new plants should be good for 80 years, what are the economic risks? JFDI. It's utterly absurd.
  • The risk is of something cheaper coming along in a decade and rendering it obsolete. No nuclear company is willing to take that gamble so the only way it works is if governments guarantee a price for the power or directly underwrite the costs.
  • The risk is of something cheaper coming along in a decade and rendering it obsolete. No nuclear company is willing to take that gamble so the only way it works is if governments guarantee a price for the power or directly underwrite the costs.

    Nothing is cheaper nor ever will be. Nothing. And everybody knows that.
  • Martin54 wrote: »
    The risk is of something cheaper coming along in a decade and rendering it obsolete. No nuclear company is willing to take that gamble so the only way it works is if governments guarantee a price for the power or directly underwrite the costs.

    Nothing is cheaper nor ever will be. Nothing. And everybody knows that.
    Currently, onshore wind is about 2/3 the cost of nuclear, biomass and large scale photovoltaic about the same. Combined cycle gas is cheaper, but almost certainly doesn't fully cost the environmental impact of burning fossil fuels (eg: no contribution to carbon offsetting). If we get fusion in the next few decades that will probably be initially more expensive, but it's likely that if fusion becomes commercial this might prove cheaper (but irrelevant for current nuclear build as that's not going to happen in the 30-40 year lifetime of the plant).
  • There's also storage. There's about eight different ways storage could come online that would allow a fully renewable energy network.
  • Martin54 wrote: »
    The risk is of something cheaper coming along in a decade and rendering it obsolete. No nuclear company is willing to take that gamble so the only way it works is if governments guarantee a price for the power or directly underwrite the costs.

    Nothing is cheaper nor ever will be. Nothing. And everybody knows that.
    Currently, onshore wind is about 2/3 the cost of nuclear, biomass and large scale photovoltaic about the same. Combined cycle gas is cheaper, but almost certainly doesn't fully cost the environmental impact of burning fossil fuels (eg: no contribution to carbon offsetting). If we get fusion in the next few decades that will probably be initially more expensive, but it's likely that if fusion becomes commercial this might prove cheaper (but irrelevant for current nuclear build as that's not going to happen in the 30-40 year lifetime of the plant).

    Nothing touches the energy density of nuclear as you know Alan and all of the massive benefits in land use, environmental impact (no bird, bat and flying insect slaughter). Fusion can never work, as you above all must know. Biomass, PV, wind are worse rip offs than fusion. It just wastes money. They do harm. I know, I know. Prove it. I will. Nigeria will not catch up let alone surpass us on shit.
  • There's also storage. There's about eight different ways storage could come online that would allow a fully renewable energy network.

    Uh huh.
  • Martin54 wrote: »
    Has any nuclear power plant ever been constructed without massive government money?

    I should hope not, they should all be public sector.
    The point is that they aren't actually viable without welfare, without heavy taxpayer subsidies. Which is stupid.

    Find me energy sources which don't require v handouts and don't enrich some glad handing business types.

    And in Saskatchewan we had Cameco do "arms length" selling of uranium to a Swiss company they set up to dodge $2.8billion and tax. And they got away with it. Older article gives the background. https://saskforward.ca/don-kossick-corporate-tax-evasion/
  • Sorry? Fission is the only possible green, sustainable, rational, global energy source. What's wrong with welfare, heavy taxpayer subsidy? Why is it stupid? Rather than throwing money away (fusion) and worse ('renewables')?
  • Of course, the best and greenest option is re-assessing our lifestyles and improved efficiency of our gadgets such that our energy requirements are cut significantly.

    The renewable options will vary with geography and local resources, but in many places are a sustainable and rational approach. Last year in Scotland 90% of our electrical use was from renewables (a mix of mostly on and off-shore wind, the old hydroschemes with some small new capacity added, and solar - with plans for wave and tidal power in some places). In Iceland geothermal is a massive resource, and the same would be true of parts of East Africa and other regions. Solar power is a good bet in desert areas, especially closer to the equator where you don't have to worry so much about what you do in winter with short days.
  • Martin54 wrote: »
    Sorry? Fission is the only possible green, sustainable, rational, global energy source. What's wrong with welfare, heavy taxpayer subsidy? Why is it stupid? Rather than throwing money away (fusion) and worse ('renewables')?

    Why? What exactly is wrong with solar, wind, hydro and geothermal such that fission is the only possible energy source to use?

    Any assessment of what works that is bound by current technology is already in trouble. I've watched in frustration as certain people spent years poo-poohing solar as too expensive (Australia of course has copious sunshine as a resource), and meanwhile there were businesses in China working out how to make the panels cheaper that then went and made huge amounts of money selling those cheaper solar panels.

    Then it was all about how you couldn't do the storage. So people are now working out the storage.

    There are plenty of energy sources that nature provides to us. Most of the issues are technological ones, and when it comes to technological problems, while one bunch of people are busy declaring that it will never work, there quite frequently is another bunch of people figuring out how to make it work.
  • edited September 2020
    There's also storage. There's about eight different ways storage could come online that would allow a fully renewable energy network.

    I don't think that's true in the UK, for a number of reasons, though I wish it was. I'm not a power engineer, but I do hold a degree accredited by IEE (IET) and I think I understand the issues.

    At the moment, the grid contains a number of high-inertia spinning things (turbines in nuclear and CCGT plants) which, with some care, can be brought into synchronous phase and connected together. Onto that can be added smaller generating units, including those which generate DC (solar and wind) which is then converted in small inverters to ac, which can then also operate phase-locked. As far as I know, at the moment a 'black start' is not possible using a bunch of small inverters alone, as stable grid operation cannot be established using the very large numbers of small inverters without the large-inertia generating sets holding it all together.

    On top of that, where we build enough wind-turbines to provide average power requirements on an averagely-windy day, we face two problems - one being where the wind drops in January for a week, and the other being when it is very windy over the same period. In the first instance, you mention storage - yet I have read figures for the (heavily projected) cost of storage which wildly exceed those of new-nuclear (I'll come back to this in a minute) for the kind of Squigga-Joules we are talking about, and where the technologies discussed seem to me to fall onto the realms of fusion - here's an idea, that might work one day, but which is currently so expensive that no-one has got it off the bench - even a very large (CERN) bench. Much more prosaically, in the second (windy) scenario, we have too much generation capacity and the wind units can end up pricing each other out of the market.

    I am very worried by the climate emergency, and I am also very worried by the long-term waste storage and decommissioning problems presented by past (and as far as I know current) fission reactors. But if it is true that we need base-load capacity, I would rather it were nuclear than CCGT, for climate reasons. If we had a proper go at costing the decommission and storage cleanup of nuclear generation, then the cost-advantage of reducing its contribution to the grid (now possible with load-following nuclear generation; a point sometimes missed by detractors) when wind is available, would be clear, and despite their great cost to build, it would make sense to reduce their run-hours wherever we could so as to minimise nuclear waste and thus to minimise the overall cost associated with running the whole grid at a given load on a given day.

    So it seems to make more sense to me to look at *how* a grid can operate, and what you need to produce and distribute however many squigga-watts, in an integrated system where some types of generation rely on the existence of others. Just pitting one type of generation against another on pure cost does not make sense when there are other issues at play. At the same time, having an accurate whole-life cost model - including environmental costs - is essential, or else one cannot optimise the operation of the whole system.

    It looks like government-level operation of such a system, as opposed to commercial competition of different operators, is pretty much vital - even wrapping up government-level operation as a system of 'market' rules under which pretend competition takes place, is likely to generate perverse incentives and outcomes.
  • Martin54 wrote: »
    Has any nuclear power plant ever been constructed without massive government money?

    I should hope not, they should all be public sector.
    The point is that they aren't actually viable without welfare, without heavy taxpayer subsidies. Which is stupid.

    This is only really true because fossil-fuel electricity generation does not factor in the HUGE environmental costs. For example, if you made coal-generating plants pay to cost of the consequential damage health resulting from their pollution, they would have to factor that into the cost of production and electricity for coal would be expensive....

    AFZ
  • Martin54 wrote: »
    Has any nuclear power plant ever been constructed without massive government money?

    I should hope not, they should all be public sector.
    The point is that they aren't actually viable without welfare, without heavy taxpayer subsidies. Which is stupid.

    This is only really true because fossil-fuel electricity generation does not factor in the HUGE environmental costs. For example, if you made coal-generating plants pay to cost of the consequential damage health resulting from their pollution, they would have to factor that into the cost of production and electricity for coal would be expensive....

    AFZ

    Excellent.
  • Martin54 wrote: »
    The risk is of something cheaper coming along in a decade and rendering it obsolete. No nuclear company is willing to take that gamble so the only way it works is if governments guarantee a price for the power or directly underwrite the costs.

    Nothing is cheaper nor ever will be. Nothing. And everybody knows that.
    Currently, onshore wind is about 2/3 the cost of nuclear, biomass and large scale photovoltaic about the same. Combined cycle gas is cheaper, but almost certainly doesn't fully cost the environmental impact of burning fossil fuels (eg: no contribution to carbon offsetting). If we get fusion in the next few decades that will probably be initially more expensive, but it's likely that if fusion becomes commercial this might prove cheaper (but irrelevant for current nuclear build as that's not going to happen in the 30-40 year lifetime of the plant).

    OKayyyyyy. Martini bets a buck:

    If the US only used unreliables it would need at least 25% of its land. Up to 50% (1)

    The footprint of the current energy infrastructure is 0.5% - 50 x less. Up to 100 x less. (2)

    Wind power generation and (virtually non-existent) storage doesn’t return the investment in energy by at least an order of magnitude: (3)

    EROI (Energy Return On Investment)
    Nuclear (cement CO2 only): 75
    Hydroelectric Dams (renewable!, cement CO2 only): 35
    Coal (which gave us the industrial revolution), Gas, Oil (CO2): 30
    Wind (unreliable, must have gas backup = CO2): 4
    Biomass : 4
    Solar PV (unreliable, must have gas backup = CO2): 2

    (1) (2) Smil, Power Density… 247
    (3) Weissbach et al, …EROI… https://doi.org/10.1016/j.energy.2013.01.029

    This needs a spreadsheet, to show the contribution of each and the even more trivial geothermal and tidal and other indicators, but the site can’t facilitate that?

    The unreliables are a joke. Or con in the case of PV, by Musk. And fusion technofix. Although the savants forever 25 years away from harnessing it witlessly con themselves. Fission plants should easily double their lifetimes. Every claim I make is backed up, but the point has to be made. We have the technology. And it is 80% (ok, 98%, but poetry, you know?) fission and 20% (ok, 2%) hydroelectric.
  • Martin54 wrote: »
    (1) (2) Smil, Power Density… 247
    If you can supply a full reference, preferably with a doi or similar link to the reference, then we can examine the reference.
    (3) Weissbach et al, …EROI… https://doi.org/10.1016/j.energy.2013.01.029
    You should also read the comments and rebuttals that follow that article that demonstrate the deficiencies of the EROI parameter (and, thus that this shouldn't be considered in isolation) and also the particular calculations of Weißbach et.al. which are applied to specific power plants which could possibly be 'average' values but certainly different examples would produce different numbers (eg: in wind power they give an EROI of 16 for their example at Schleswig-Holstein, which they reduce to 4 based on the need to invest in buffering - though I'm not immediately seeing where in the paper they define that buffering technology. But they then state that in other locations EROI of 25 are achieved). The comments and rebuttals highlight various factors not included in the calculations (even my inexpert eye reading the original paper noticed that they explicitly excluded flaring and gas loss in the costs of supply gas to power stations). At the least Weißbach et.al. should have generate values of EROI that exhibit the range of values that are actually achieved, which would to my mind be a wide spread from highest to lowest (even if limited to 90% percentiles).
  • Smil and from MIT.

    And I will read the Weißbach link too.

    Alan, you are THE expert. @mark_in_manchester's view is expert too. Neither of you is PhD. in the narrow field, but you're more than good enough for me. Arm jest uh born agen evidence based environmental humanist purged of over 50 years of alarmism.
  • It was interesting reading the news reports of Microsoft raising their test data centre off Orkney, that although the electricity supply was all from renewable sources, they had no problems with reliability.
  • Martin54Martin54 Shipmate
    edited September 2020
    Pendragon wrote: »
    It was interesting reading the news reports of Microsoft raising their test data centre off Orkney, that although the electricity supply was all from renewable sources, they had no problems with reliability.

    Uh huh. What, 25kw? Yeah, sure, that'll run Nigeria.
  • Martin54 wrote: »
    Has any nuclear power plant ever been constructed without massive government money?

    I should hope not, they should all be public sector.
    The point is that they aren't actually viable without welfare, without heavy taxpayer subsidies. Which is stupid.

    This is only really true because fossil-fuel electricity generation does not factor in the HUGE environmental costs. For example, if you made coal-generating plants pay to cost of the consequential damage health resulting from their pollution, they would have to factor that into the cost of production and electricity for coal would be expensive....

    AFZ

    But it is a dynamic equilibrium of course, as there are OOM a billion or ten people who would not have lived without fossil-fuel electricity generation.
  • Martin54 wrote: »
    (1) (2) Smil, Power Density… 247
    If you can supply a full reference, preferably with a doi or similar link to the reference, then we can examine the reference.
    (3) Weissbach et al, …EROI… https://doi.org/10.1016/j.energy.2013.01.029
    You should also read the comments and rebuttals that follow that article that demonstrate the deficiencies of the EROI parameter (and, thus that this shouldn't be considered in isolation) and also the particular calculations of Weißbach et.al. which are applied to specific power plants which could possibly be 'average' values but certainly different examples would produce different numbers (eg: in wind power they give an EROI of 16 for their example at Schleswig-Holstein, which they reduce to 4 based on the need to invest in buffering - though I'm not immediately seeing where in the paper they define that buffering technology. But they then state that in other locations EROI of 25 are achieved). The comments and rebuttals highlight various factors not included in the calculations (even my inexpert eye reading the original paper noticed that they explicitly excluded flaring and gas loss in the costs of supply gas to power stations). At the least Weißbach et.al. should have generate values of EROI that exhibit the range of values that are actually achieved, which would to my mind be a wide spread from highest to lowest (even if limited to 90% percentiles).

    Not read yet, quaking at the cost, but let us assume wind EROI of 25, we don't have the land to scale that up, there is no economic storage - where do we pump Windermere uphill to? - and we'd need an order of magnitude more gas including by fracking. Unreliables are not scalable in land use alone. They look nearly as absurd as fusion. More in fact, Heath-Robinson contraptions with unintended consequences none of which are sustainable. Fission and hydroelectric are the only rational, humanist, sustainable options to the next ice age maximum and beyond.
  • I've said many times before (though, not actually on this thread) that I'm in favour of safer nuclear power being the only viable means of providing a realistic base load for our electricity supply (at probably about 20-25% of electricity generation). Safer being smaller reactors, and not water cooled - so I oppose the big PWR schemes that are the current plans, though I recognise that pursuing smaller gas cooled graphite moderated reactors will be more expensive (cheapest is not always best).

    But, I also believe that we need a broad energy platform that incorporates multiple production methods (the precise mix being different depending on local resources) and also some smart elements in generation and use. This would include a lot more local power generation (semi-independent from national grids), and must also include transport. Some examples of elements of this (all based on existing, proven technology - we can't make realistic energy policy based on wanting something that doesn't exist):

    Geothermal. In a few places in the world (basically where you get natural hot springs) this can include electricity generation. But, the big application is space heating - for the last decade or more we could have used ground heat for central heating instead of gas, at about the same cost as installing gas heating - especially in new builds where the infrastructure can be put in at construction stage and shared between several properties.

    Hydroelectric. One of the few "baseload" options for renewable power generation - though we still need to devise means of dealing with old dams and sediment buildup in reservoirs. Small hydro, which doesn't have big dams with all the problems they entail, can be particularly effective with multiple turbines spread along the length of almost any river deep enough that turbines can be held off the river bed without being fouled by river plants.

    Wind. Onshore and offshore, the technology is very cheap to install and maintain (obviously off shore that bit harder to maintain), the output is obviously variable but across a large enough area it's very unlikely that output will ever fall to zero. Inertia of big turbine blades provide an automatic storage and supply smoothing function. They occupy a lot of space, but don't need to be exclusive use of that space - the ground around turbines can be farmed, or in upland areas returned to active peat bogs (which are a big carbon sink as well as vital for water storage and flood mitigation and as ecosystems). Vertical axis wind turbines have advantages in urban areas with uncertain, gusty and constantly changing wind direction - but if they stop they need an energy input to get going again which is why they're not commonly used.

    Solar. Again, quite cheap and easy to install, ideally suited to urban areas with lots of roof space to mount PV panels on. A set of panels on the roof of a house with a small battery pack can provide most of the energy needed for the home (heating, using ground source, lighting etc) though probably not extra loads (eg: charging one or more electric vehicles) and in somewhere like the UK with distinct seasons may need additional source of energy over the winter due to reduced daylight hours. In some locations with lots of strong sunshine (so, not Scotland!) tracking mirrors focussing sunlight onto a central receptor to generate steam are more efficient than PV panels. Unlike wind, there are few options for using ground around solar power farms for other purposes.

    Biofuels. I don't think these will ever be a major component in our energy mix. We probably will need some bio-oil to replace liquid fuels in some transport applications where a fully electric alternative doesn't exist (aviation is an obvious example). And, a few coal fired power stations can be converted to burn fuel from coppiced woodlands to boost baseload capacity (may be useful in locations without a significant hydro potential).

    Smart power use. At the other end of the grid, smart technology can be used to vary energy use to smooth out demand to better match current generating capacity and to link together local and grid generation. We already have much of the technology, used in regulating domestic power generation on feed-in tariffs. We'll probably need all car chargers to respond to capacity - and reduce charging when generation capacity falls (and, potentially feed back into the grid if essential demand exceeds capacity), and have other users phase to lower use at times when insufficient generating capacity is available (maybe, dim street lighting shut down display lighting in closed shops ...)

    [probably it's only the first paragraph on 'safer nuclear power' part of all that which is directly relevant to this thread]
  • Thanks as ever for your peerless consideration Alan. What are the risks of large (economy of scale), 100 year, PWR (magic word pressure there...) sites and how have any been realised? All nuclear accidents combined, outside the Soviet Union, since Windscale in 1957 (in the desperate race for an H-bomb) have directly killed less than 10 people. Fossil fuel processing will have killed at least three OOM more and at least five in consumption. The Great Smog of London of 1952 killed 4,000 alone.

    And why only 20% when France produces 70%? 20% from expensive, high environmental, low density energy unreliables is more like it, although how can they possibly compete except in marginal places like Iceland with the same population as Coventry? How do they in France?

    None of the non-nuclear power sources can begin to address climate injustice except the biggest possible hydroelectric schemes, especially Inga, which the all but terrorist XR-type Malthusian alarmists have stopped the World Bank financing.
  • Martin54Martin54 Shipmate
    edited September 2020
    !
  • Martin54 wrote: »
    What are the risks of large (economy of scale), 100 year, PWR (magic word pressure there...) sites and how have any been realised?

    The biggest risks for nuclear relate to significant core melting - which may be contained or may lead to secondary events (at Chernobyl this lead to ignition of the graphite moderator and a fire that burnt for days, at Fukushima partial core exposure resulted in hydrogen production which caused the explosions). When a reactor is shut down the thermal output doesn't immediately cease, in the first hour or so after shut down a reactor still produces about 6% of the heat that it produced at full power - this heat production decays over time, but reactor fuel needs to be cooled to prevent damage to it for years after shutdown. In a water cooled reactor this means that the water needs to be actively pumped around the core, loss of power to pumps even for more than a few minutes leads to the water boiling with a significant increase in pressure and exposure of the top of the core which is why these reactors rely on batteries (for short, <1h, periods) and diesel back-up generators in the event of loss of power from the grid. The risks of loss of grid power are quite high (events leading to this include storms bringing down power lines, damage to local substations etc - in effect anything that might lead to a power cut to anyone) and in the 30-40 year design life of a reactor can be expected to occur at least once, probably several times. A serious accident will occur if power isn't restored (either the grid is reinstated or the backup generators started) before the batteries run down; that shouldn't happen, but did at Fukushima (and at Chernobyl where those back-ups had been deliberately turned off). Loss of primary coolant is a frequent accidental scenario in water cooled reactors - in several cases pressure release valves open in response to momentary fluctuations in reactor power or secondary coolant supply and have failed to shut resulting in venting of steam, which shouldn't lead to as serious a melt down (the coolant is still being pumped around) providing an adequate supply of water is available to top up the primary coolant circuit as fast as it boils off until the vent can be closed (which isn't necessarily easy as this is a vent releasing superheated, radioactive steam), Three Mile Island is the most serious accident of this sort. Loss of secondary coolant also leads to reductions in cooling efficiency, but the primary circuit should cope once the reactor is shut down.

    Gas cooled reactors have a different set of emergency scenarios. But, loss of pump power isn't one of them. Gas naturally circulates, so in shut down the circulation is sufficient to prevent core meltdown even without active pumping (in practice, you would still run the pumps to circulate the gas) so loss of grid power, which is by far the likeliest event, wouldn't leave operators scrambling around to get emergency power re-engaged or face a meltdown. Loss of primary coolant is still a risk.

    Gas is less efficient at moving heat from an operating reactor, which limits the core size and operating temperature - and hence output power. Current AGRs are probably the biggest reactor that can be achieved using gas cooling. Water is much more efficient at moving heat, so you can build reactors with hotter and larger cores, making much more power at much lower cost per kWh, and hence PWRs and BWRs are the preference on economic grounds though present reactors are not much bigger than AGRs in terms of output.

    We're still in the initial building phases of truly large PWRs and, although they've been certified as safe enough by regulators, they carry the same risks as current operational designs - the accident frequency would probably be about the same, but the consequences of a severe accident could be much higher. And, they're all still being built on a design lifescale of 30-40 years. We simply don't have the knowledge of material behaviour to know how vital structural components will last beyond that while subjected to high pressure, high temperature and radiation.
  • Martin54 wrote: »
    Pendragon wrote: »
    It was interesting reading the news reports of Microsoft raising their test data centre off Orkney, that although the electricity supply was all from renewable sources, they had no problems with reliability.

    Uh huh. What, 25kw? Yeah, sure, that'll run Nigeria.

    Orkney is small. It only has room for a relatively small amount of energy generation, but only has relatively small needs. Nigeria, being much bigger, has much bigger energy needs... but also much more capacity to generate energy.

    In other words, your attempt at a comparison as if the amount of energy generated in Orkney is any way remotely relevant to what would happen in Nigeria, fails.
  • orfeo wrote: »
    Martin54 wrote: »
    Pendragon wrote: »
    It was interesting reading the news reports of Microsoft raising their test data centre off Orkney, that although the electricity supply was all from renewable sources, they had no problems with reliability.

    Uh huh. What, 25kw? Yeah, sure, that'll run Nigeria.

    Orkney is small. It only has room for a relatively small amount of energy generation, but only has relatively small needs. Nigeria, being much bigger, has much bigger energy needs... but also much more capacity to generate energy.

    In other words, your attempt at a comparison as if the amount of energy generated in Orkney is any way remotely relevant to what would happen in Nigeria, fails.

    Indeed it does. Nigeria will need ten thousand times more. With nothing like the wind and tidal resources. How are they going to get to that?
  • orfeoorfeo Shipmate
    edited September 2020
    Martin54 wrote: »
    orfeo wrote: »
    Martin54 wrote: »
    Pendragon wrote: »
    It was interesting reading the news reports of Microsoft raising their test data centre off Orkney, that although the electricity supply was all from renewable sources, they had no problems with reliability.

    Uh huh. What, 25kw? Yeah, sure, that'll run Nigeria.

    Orkney is small. It only has room for a relatively small amount of energy generation, but only has relatively small needs. Nigeria, being much bigger, has much bigger energy needs... but also much more capacity to generate energy.

    In other words, your attempt at a comparison as if the amount of energy generated in Orkney is any way remotely relevant to what would happen in Nigeria, fails.

    Indeed it does. Nigeria will need ten thousand times more. With nothing like the wind and tidal resources. How are they going to get to that?

    By using different resources. Orkney has nothing like the solar or hydro resources of Nigeria, for example, and I'm a little mystified by your determination to treat the entire world as if it must be uniform. I grant you that nuclear reactions run in much the same way regardless of location, but the natural world is not so boring. :wink:

    Nigeria's energy problems are to do with the grid and infrastructure, not with a lack of resources to make energy from.
  • Thanks again Alan. When I toured Dungeness B AGR after it had gone operational, I recall that I was told it was failsafe, that if power failed the damper rods, which were held aloft magnetically, would fall. So were they telling porkies? Being economical with the truth? Would there be a core melt if there was no power at all? Like at Fukushima where the massive overreaction - panic - to a leak that killed no one killed over a thousand people directly and thousands more indirectly.
  • [
    Martin54 wrote: »
    Thanks again Alan. When I toured Dungeness B AGR after it had gone operational, I recall that I was told it was failsafe, that if power failed the damper rods, which were held aloft magnetically, would fall.

    That's an AGR. It doesn't pump water around. Alan's message mentions that pump failure is not a safety issue for AGRs, because the core continues to cool as the gas circulates, even without pump power.
  • Martin54Martin54 Shipmate
    edited September 2020
    Of course, the best and greenest option is re-assessing our lifestyles and improved efficiency of our gadgets such that our energy requirements are cut significantly.

    The renewable options will vary with geography and local resources, but in many places are a sustainable and rational approach. Last year in Scotland 90% of our electrical use was from renewables (a mix of mostly on and off-shore wind, the old hydroschemes with some small new capacity added, and solar - with plans for wave and tidal power in some places). In Iceland geothermal is a massive resource, and the same would be true of parts of East Africa and other regions. Solar power is a good bet in desert areas, especially closer to the equator where you don't have to worry so much about what you do in winter with short days.

    Gadgets like cars? Cookers? Fridges? Air con? For two hundred million Nigerians and rising? Thirty million households. Again Iceland is Coventry. Solar power luckily can never be scaled up to pave and destroy the Mojave or any non-fertile region. Close to the equator means removing the rain forest.

    (The previous comment was in response to your last.)
  • [
    Martin54 wrote: »
    Thanks again Alan. When I toured Dungeness B AGR after it had gone operational, I recall that I was told it was failsafe, that if power failed the damper rods, which were held aloft magnetically, would fall.

    That's an AGR. It doesn't pump water around. Alan's message mentions that pump failure is not a safety issue for AGRs, because the core continues to cool as the gas circulates, even without pump power.
    And, these are different issues. Almost all nuclear reactors contain gravity driven control rods that will shut down the reactor automatically and very quickly as you describe for the AGRs - actually, in most cases they'd be powered into place faster than gravity alone, shutting off the magnets and letting gravity do the rest is the failsafe in case the motor stops working. Exceptions would be the CANDU reactors where control rods are inserted horizontally, and the Soviet VVER and RMBK reactors which are entirely mechanically driven.

    Issues with cooling relate to what happens after those control rods are in place and fission has ceased.
  • orfeo wrote: »
    Nigeria's energy problems are to do with the grid and infrastructure, not with a lack of resources to make energy from.
    Nigeria has two large rivers, which would equate to some considerable hydro potential - though with the heavy deforestation and associated soil loss during the rainy season dams are liable to sedimentation limiting longevity (deforestation is, of course, an issue that needs addressing anyway). And substantial highlands with smaller rivers draining them which would also be suitable for hydro. With 500miles (ish) of coast wave and tidal are going to be options in places. The far north of the country is arid desert, ideal for solar - though a long way from anywhere the power would be needed. As @orfeo said, the issues are with developing and maintaining a distribution infrastructure rather than actual potential for resources.
  • Exceptions would be the CANDU reactors where control rods are inserted horizontally, and the Soviet VVER and RMBK reactors which are entirely mechanically driven.
    The book I've recently been reading about the Chernobyl disaster also gives the impression that, at a certain point of control rod insertion, the RBMK reactor core in fact "speeds up" rather than being damped; it further suggests that excess heat at Chernobyl (due to earlier misjudgemrents) caused the rods to deform which meant they jammed in precisely this wrong position. Is that correct?

  • Exceptions would be the CANDU reactors where control rods are inserted horizontally, and the Soviet VVER and RMBK reactors which are entirely mechanically driven.
    The book I've recently been reading about the Chernobyl disaster also gives the impression that, at a certain point of control rod insertion, the RBMK reactor core in fact "speeds up" rather than being damped; it further suggests that excess heat at Chernobyl (due to earlier misjudgemrents) caused the rods to deform which meant they jammed in precisely this wrong position. Is that correct?
    Yes, pretty much. The RMBK design is graphite moderated and water cooled, the water also acts as a moderator. The control rods have a graphite tip, and as they're inserted they displace the water in the channels; the graphite is designed to compensate for the displaced water so that the reactivity of the reactor is controlled only by the boron in the rods which made modelling of the reactor control much simpler. The issue is that water is also a weak neutron absorber and graphite isn't, so although the moderation effect is the same inserting the graphite tip reduces the number of neutrons absorbed, increasing the reactivity until the boron carbide section of the rod enters the reactor.

    The rods are inserted into channels which carry cooling water, with very little space between the rod and the channel wall. This acts as an inefficient hydraulic system similar to a damper, pushing against the rod as it's inserted - which is why they're all motor driven and relatively slow to insert for an emergency scram. In the hours preceding the accident in 1986 the operators had inserted the rods to reduce the reactor output - they were actually trying to see if they could generate enough power from the turbine inertia to run the cooling pumps without the need for an emergency diesel generator. This put the whole core into an unstable condition, well outside design operating limits - there's some scope to change operating conditions for a bit more or less power, but no one designing the thing thought anyone would take it down to barely operating (let alone hold it there for a significant period of time). Reactor power started to fall, the operators pulled the control rods back out to compensate, reactor power then shot up and as the operators tried to reinsert the rods the reactor heat had risen to the point where the channels deformed such that the rods no longer fitted, and jammed in a partially inserted state where the graphite tips made things even worse (though, by that stage it would have made no difference).
  • [
    Martin54 wrote: »
    Thanks again Alan. When I toured Dungeness B AGR after it had gone operational, I recall that I was told it was failsafe, that if power failed the damper rods, which were held aloft magnetically, would fall.

    That's an AGR. It doesn't pump water around. Alan's message mentions that pump failure is not a safety issue for AGRs, because the core continues to cool as the gas circulates, even without pump power.

    So it did. Failsafe PWR anyone?
  • My concern is that failure by the West to advocate nuclear power will lead to less safe Russian designs spreading across the developing word. Is that a legitimate fear?
  • Probably not, as the Russian designs a) have very bad press and b) are still quite expensive.

    Now, if you were to talk about Chinese reactor designs ...
  • Alan & Orfeo, we got here from coal, oil, gas and nuclear in two hundred years. The world is the same. Everywhere. Except Iceland=Coventry. Paving the Sahel with PVs, putting turbines above and below 500 miles of coastal waters won't touch Nigeria's requirements even if it were to happen, which is less likely than fusion. Fission will. Watch them. Watch the Chinese (5% nuclear, doubling in progress and again by 2100) and/or the French (71% nuclear) and/or the South Koreans (29%) make a fortune providing them. PWRs. And the grid to go with them.

    Why choose expensive low energy density when fission is three times cheaper at least? I don't understand? Polar bears? What?
  • Probably not, as the Russian designs a) have very bad press and b) are still quite expensive.

    Now, if you were to talk about Chinese reactor designs ...

    OK.... are they any good?
  • Leorning CnihtLeorning Cniht Shipmate
    edited September 2020
    Martin54 wrote: »
    Why choose expensive low energy density when fission is three times cheaper at least? I don't understand? Polar bears? What?

    You keep asserting this, but it doesn't seem to be true.

    Here's Alan from earlier:
    Currently, onshore wind is about 2/3 the cost of nuclear, biomass and large scale photovoltaic about the same. Combined cycle gas is cheaper, but almost certainly doesn't fully cost the environmental impact of burning fossil fuels

    Can you justify your claim that renewables are "expensive", and in particular 3 times the price of nuclear?
  • Martin54 wrote: »
    Why choose expensive low energy density when fission is three times cheaper at least? I don't understand? Polar bears? What?

    You keep asserting this, but it doesn't seem to be true.

    Here's Alan from earlier:
    Currently, onshore wind is about 2/3 the cost of nuclear, biomass and large scale photovoltaic about the same. Combined cycle gas is cheaper, but almost certainly doesn't fully cost the environmental impact of burning fossil fuels

    Can you justify your claim that renewables are "expensive", and in particular 3 times the price of nuclear?

    Because they can't be scaled without massively reducing fertile land, slaughtering winged creatures to extinction and generating vast amounts of toxic waste (PV). The table above shows nuclear EROI at 75 and taking the very best case for unreliables of 25.

    Tractors, fertilizer, cement, infrastructure, grids, roads, rail, goods and hydrogen for carbon free aviation and ground vehicles all need abundant, cheap, fission generated electricity. That will save the rain forests.
  • Martin54Martin54 Shipmate
    edited September 2020
    Ooh and desalination plants. And pumping stations, to maintain land below sea level. They need it too. We need much more electricity.
  • BroJamesBroJames Purgatory Host, 8th Day Host
    Martin54 wrote: »
    <snip>The table above shows nuclear EROI at 75 and taking the very best case for unreliables of 25.
    <snip>
    But note Alan’s critique of said table.
  • Alan is one of the most trusted people here especially on science and technology. In this field of nuclear technology I think he counts as an expert. Who are we to believe, Alan or Martin who makes claims but can't back them up?
  • BroJames wrote: »
    Martin54 wrote: »
    <snip>The table above shows nuclear EROI at 75 and taking the very best case for unreliables of 25.
    <snip>
    But note Alan’s critique of said table.

    I did, which is why I used the most unrealistic unreliables EROI, despite the conservative Weissbach figures. Unreliables scaled up to match nuclear would need orders of magnitude more land.
  • orfeoorfeo Shipmate
    edited September 2020
    Martin54 wrote: »
    Alan & Orfeo, we got here from coal, oil, gas and nuclear in two hundred years.

    See, I live in a part of the world that simply doesn't have nuclear power. Australia has one-third of the world's uranium deposits, but we have never, ever had a nuclear power station.

    So who is this "we" you are talking about? And what part of the Industrial Revolution do you think relied on nuclear energy?

Sign In or Register to comment.