Two posters always worth listening to,
@Trommel and
@globalstockguru, recently had a passing exchange about the future of nuclear power on another thread:
http://hotcopper.com.au/posts/20906120/single
In light of the upcoming UAL AGM, and in the context of the central role I think graphite will play in the next generation of commercially-viable nuclear power stations, I thought a nuke thread would be timely.
This April 2016 state-of-play from Neutron Bytes, which I think is just an enthusiast's blog, might be a good start point for discussion (until UAL lists and gets its own HC threads).
Some brief reasons why, contrary to stockguru's suggestion that 'nuclear is done, finished' on that other thread, I think that pebble-bed/gas-cooled nuclear reactors will be a big part of the world's future electricity generation:
Safety (of course).
The essence of Gen IV nuclear reactors is that, being gas-cooled and moderated, rather than water-cooled and mechanically moderated, the engineering can sidestep the complicated problems of (contaminated) water husbandry (either boiling or pressurised), and variable fission-reaction operating parameters. It's the former, in particular, that has been at the heart of all major nuclear accidents. At Chernobyl the damage was done by the massive coolant-steam explosions (resulting from multiple human/systemic screw-ups, sure). At Fukushima, the tsunami (act of god, sure) destroyed even the emergency generator and water coolant systems so that even though the reactor was shut down, serious overheating still occurred. At Three Mile Island it was essentially a stuck water-coolant valve that led to emergency shutdown. (At Commie Russia Kyshtyn back in the early nuke days it was rubbish facility management and an explosion in a storage tank). And if you browse through
this consolidated list of nuke incidents you'll see that, overwhelmingly, the serious incidents have been associated not with the nuclear material or reactions 'as such', but the complicated engineering and management demands of water as primary coolant. Without delving too far into the technical details, the demands of water/steam heavy engineering, intensive operational management and high maintenance have always in turn demanded that fission reactions have had to be conducted at the 'trickier' end of the engineering spectrum, that is, with more systemic risk in terms of operation, maintenance and inspection (more room for human error), refuelling and moderation methods, and power husbandry generally ie spool up/down regimes, and energy capture design. Generation III - essentially high pressure nukes - have been a marked improvement but the fundamental engineering complications of tons of piping hot, often high pressure, often contaminated, water remain.
Pebble bed reactors, which are gas cooled and ideally thermally rather than mechanically moderated ('throttled'), have been increasingly demonstrated at these early stages at least to significantly mitigate if not eliminate these problems. No least, unlike most water-based cooling and control rod moderation systems, the nuclear fission is 'passively' safe: as a fission reaction heats up a process of Doppler broadening reduces the availability of high-speed neutrons for further fission so the reaction slows and cools in a self-regulating way.
Another safety advantage is that whereas coolant water absorbs the free neutrons of a fission reaction it is cooling and so becomes 'radioactive', inert gases like helium, nitrogen and Co2 are resistant to them, leading to much less contaminated by-product.
Efficiencies in energy capture
The 'passive' moderation and gas cooling in pebble-bed reactors (counter-intuitively) allows the reaction itself to be maintained at a much higher temperature than in a water-cooled/control rod modulated system (hence the role of graphite's excellent thermal and neutron-husbandry characteristics in the U-fuel pebbles/bed array, by the way). This in turn yields far more efficient thermal-energy capture possibilities. Particularly if there is insignificant neutron capture in the cooling gas itself (helium, say), direct thermal energy-harvesting can occur across a much higher differential. Some prototype designs have the coolant gas driving generator turbines directly, but even with the (traditional) intervention of a secondary thermal energy transfer component, the electricity-generation efficiencies are much higher.
There is also the authentic possibility of using heated (uncontaminated) coolant gas directly, in industrial processes, and even - don't laugh - domestic heating, etc.
Production and construction simplicities
Overwhelmingly the bulk of the engineering and construction costs in Gen II-III nuclear power stations are associated with the cooling and moderation systems. The 'beating heart' of a plant - the fission reactor - is generally small and surprisingly un-complex. (If you've even been shown around a nuclear power station you will understand). What isn't of course is the huge shroud of cooling systems, the apparatus of the moderating system, the multiple layers of redundancy...and of course, the water system. Oceans of the bloody stuff. It's here that the engineering and construction complexities and all the safeguard, regulatory, environmental and planning/approval difficulties that flow from them, really multiply (as does, as mentioned earlier, the systemic prospect of operational human error).
The nature of pebble-bed design and construction, once it is proven, will in fact be ideally suited to a greatly simplified, modular, even largely off-site pre-production process. If you think about it, if the husbandry of coolant water constitutes one of your greatest engineering design and construction headaches, then every new nuke power station becomes a 'one-off' project. Where do I get enough water? Where and how do I cycle/pump/decontaminate it? How do I make it a squillion-fold redundant? What are the particular locational 'act of god' risks against which I have to design? Can I rely on the in-location infrastructure? How above all else do I get this bloody thing approved??!! All of these construction and production matters are multiplied ten, a hundred fold, if at the core of your nuclear power plant is a fission reaction demanding that inherently 'active', water-cooled safety approach. The endless explanations about how you're going to cope with 'reaction melt-downs' and 'critical runaways' using 'triply-redundant emergency shutdown protocols'...I mean, come on. That sh*t scares even me. And it's all about the water, in my view.
But once the move away to a (self-throttling) passive nuclear fission reaction is really proven and bedded into the public understanding, well...the economies-of-scale of the modular, off-site design approach it empowers becomes immeasurably more feasible, and will in turn feed back into making the building of new nuke power stations much less physically and conceptually intimidating for the people who have to live near them. And critically - maybe the most important point - it becomes more viable to stick them in the middle of bloody nowhere. Rather than on lovely coastlines, on lovely lakes, in the densely populated - and often act-of-god/nature vulnerable - places that lots of water invariably attracts.
Cost, cost, cost
All of the above which leads to...realistic cost, cost, cost-return. Bankable again. Building a nuke power station is bloody expensive, and since Fukushima has just not been worth it, frankly. Just not worth it. But it's fair to say that a big and probably un-measurable component of that unviable cost is due to a stubbornly resistant, globally-domain reluctance on the part of many us to take the obvious (I think the inevitable) step into what we still apparently regard as the scary world of fizzing atoms.
Industrial health and a sustainable energy future
Which is just nuts. Nuts. Because firing a neutron at a chunk of U-235 causing it to turn into a chunk of barium-139 and a little puff of krypton-141 (or wotsit) is not really any different to holding a match to a bit of coal and turning its captured carbon/nitrogen/hydrogen/sulphur/oxygen into a lump of (mostly) carbon, and puffs of CO2, SO2, NO (and a bit of H2O).
In both cases energy is released, and potentially dangerous by-products are created.
It's just that...well, in the U-235 case the whizzing neutrons and the subatomic bonding energy they unshackle represent about 3.5-4 million times as much energy as the same amount of oxidising coal releases in the form of heat and light. And, to give you bleeding heart greenies a rough idea, to match a 1000 megawatt electricity (MWe) nuke station...you'd need something like 10,000 tons of burnt coal a day. Over a year, even if the station is state-of-the-art best practice, this WILL - even if everything goes 'to design plan' - pump up to six, seven, maybe eight million tons of that toxic sh*t into the air.
In that time the comparative amount of actual nuclear waste produced is negligible.
Meanwhile, even adding all those vanishingly rare times when things
haven't gone according 'to design plan', the sixty-year-old nuclear power industry has to date directly and indirectly killed, at absolute most, 13-14,000 people. That's assigning an extreme worst-case like 10,000 to Chernobyl over three decades and perhaps 2000 to Kyshtyn over five. Given that these worst-two-ever both occurred in Communist Russia, one thirty years ago and one sixty years ago, the case that improving technology will only decrease an already very, very comparatively low industrial health risk-return metric considerably seems to me irrefutable. Mortality rate arising directly and indirectly from the fossil fuel energy industry across the ages, anyone? (Especially given that if we keep on going as we are, it's likely to hit 100% sooner or later...!)
So to me: it's a no-brainer, globalstocky...and any other heathen unbeliever greenie moonbat feral tree-hugger lurking out there in HC Land.
But let's have at the discussion...
(20min delay)