One problem I’ve glossed over, is the issue of size. One of the other persistent problems with our current crop of LWR’s is their vast size. While such size gives us economies of scale (making them at least vaguely economically viable) they come with a number of serious draw backs. In this chapter we will discuss the benefits and draw backs of smaller reactors. We’ll also discuss how they could be mass produced as well as the practical barriers to that.
10.1 Size definitions
Up until now, we’ve considered any reactor less than 1,000 MWe as “small”. Let us narrow this definition. We’ll refer to anything in the range of 900-200 MWe as “medium”, 200-50 MWe as “small” and less than 50 MWe as “micro”.
So what’s wrong with big reactors? I’ve already discussed the safety implications of large reactor cores (see section on LWR’s). There also the issue of decommissioning. The current plan is to remove the fuel and then strip down the interior of the reactors pressure vessels, fill it with concrete…and leave it there….for a century or two. Enquire with a nuclear engineer about what they plan to do with our vast concrete sarcophagus at this point in the future and they’ll make some vague reference to picking it up and sawing it into pieces…and how exactly do you propose to pick up a 20,000 ton block of 200 year old (mildy radioactive) concrete and steel (without it fracturing) and then cut it into pieces? I’m assuming that nuclear engineers are gambling on us developing phasers and tractor beams over the next 100-200 years! Obviously small to medium sized reactors reduce the problem. Several such reactors, the Shippingport reactor for example, were successfully loaded onto barges and moved to somewhere that they could be safely buried. One could even envisage us putting some of the smaller pressure vessels into out deep geological storage facilities, if they can be made small enough to transport. So smaller reactors give us a lot more wriggle room as we come around to decommissioning.
Another problem with these large reactors is that that they are impractical and unwieldy. Only a few of the larger nations on Earth can utilise them, as only they have an energy grid large enough to support large reactors, not to mention the financial muscle to pay for them. I recall a talk I saw in Ireland by an advocate of building nuclear power stations in the Republic. He gave as spirited a defence as I’ve ever seen of the nuclear energy issue, although he inevitably glossed over a few issues (the costs, decommissioning problems, spent fuel storage – he seemed to believe we could export nuclear waste abroad, which we can’t, that would violate IAEA rules) but gave a good account of it. Unfortunately his entire hour long talk fell apart in the last 5 minutes when he turned his attention to picking the reactor type. He noted that a single EPR or AP1000 would be impractical, we’d want a minimum of two of any reactors (unless we want to turn off half the lights in the country when its offline!). Unfortunately, 2 of either of the above would drastically stretch the Irish energy grid and probably not be practical. He favoured two of the AP600’s (since cancelled) or possibly several of the South African PBMR (also cancelled) if they became available. In short, what he seemed to be saying is nuclear power in Ireland is off the table at present because the reactors are just too darn big!
In another example, take Lithuania. They are probably one of Europe’s most enthusiastic supporters of nuclear energy. It pained them to have to turn off the remaining RMBK station in the country as part of the price for EU membership. They have been trying since without success to bring in another pair of reactors. But again they have the problem that they are a small country with neither the financial resources nor the grid capacity to manage two large reactors. Thus, they’ve been forced into a bilateral agreement with they’re neighbours, Latvia, Estonia, even Poland, to both finance this project and distribute the electricity. Of course, as always happens when governments get together the whole thing has dragged on and on! As a consequence they have yet to put ink to paper and actually order any reactors. Obviously if small to medium sized reactors were available, they could have 2 or 4 of said reactors up and running already.
Finally, as we will discuss later in this chapter, large reactors often need large engineering workshops to forge and manufacture critical parts. There are only a handful of faculties worldwide that can actually forge key parts of a reactor, such as the pressure vessel for example. Obviously this puts a significant bottle neck on potential nuclear roll out, and makes many countries dependant on foreign support. China for example, even if they can develop their own indigenous large LWR will probably need to get the pressure vessels forged in Japan, something that is unacceptable on a political level. Indeed it’s interesting to note that all of the Chinese reactor development programs (that we know about!), involve small to medium sized reactors.
Another issue is simple grid mechanics, as we can get more of them on the grid and use them more effectively if we have lots of little reactors rather than a few big ones. Better still if one of the smaller reactors unexpectedly goes offline for some reason, the consequences aren’t as catastrophic as with a big reactor suddenly shutting down. Finally there is the fact that some reactors, notably the HTGR would work better with small or medium sized cores (as discussed earlier).
10.2.1 – why small is NOT beautiful!
So there are a host of practical factors in favour smaller reactors. But what’s the down side? Firstly, economies of scale. With a small reactor, we have all the excess baggage that comes with each power station, all the fixed costs and a much smaller pay-off. As I noted earlier, even thought many smaller reactors are a lot safer than large LWR’s (even a small LWR is somewhat safer!) you would still need to put them under a containment dome. It’s this process of concrete pouring that is often a bottle neck in nuclear reactor construction. We could get around the problem by clustering reactors together, i.e putting 2 or 4 reactors not only on the same site but under the same containment dome. The one downside here is that if one reactor has a problem, it will likely spread to its neighbours. How much of a showstopper this fact is depends on which type of reactors we are discussing.
A proposed modular reactor design with four 250 MWth reactors within the same containment building working a shared pair of turbines to produce 500 MWe
Also, in the shorter term small reactors would be slower to build, especially many of those we’ve been discussing, given that they are often made out of non-standard materials. Only a few facilities in the world could build them as the entire nuclear manufacturing industry is currently geared towards large LWR’s. Turning that juggernaut around would take decades. So by opting for small reactors while we’d get safer more flexible reactors, we be paying for it, as these reactors would be slower to build (initially anyway) and probably more expensive too.
10.2.2 – Just build them underground!
There is a common misconception, that we could solve a lot of the problems with reactor construction, both large and small (though in particular the small ones) by building them in subsurface pits. Certainly it would solve some problems, notably the risk of suicide attacks by kamikaze pilots. It would also simply certain fire scenarios as the reactor would now be below the surface, which restricts the pathways for air to get in.
However, subsurface construction will not necessarily reduce costs. I’m assuming the person who thought up this one has never dug a hole in his back garden! If you have, you’d know that digging a hole is not as easy as it seems. Firstly, the soil type has a big bearing on things. Depending on where you live you could be looking at thick sticky soil that difficult to shift, loose gravely soil that collapses easily or rocky earth, that rapidly turns into bedrock (so after a while you’re not digging any more but blasting!). As we need to put foundations down under out reactor to suit the soil type, and probably piling too (due to its weight), this means we essentially need to design each reactor’s containment vessel individually to suit local soil conditions, playing havoc with conformability and increasing costs.
Another problem is water intrusion, as anyone who’s ever dug a pit, then gone in for lunch, come back out and found it full of water will know all about! Our reactor “pit” needs to be designed like the hull of a boat to stop water leaking in and flooding it. Doing that with concrete, particularly thick section of it, is always difficult. The fact that the reactor will be generating heat complicates things as it raises the risk of subsidence or settlement cracking. While this can happen if the reactor is on the surface too, putting it under ground level “complicates things”.
In general with any construction project significant efforts are made to reduce the amount of earth moving required to start construction, not increase it, as lots of earth moving nearly always results in delays, hold-ups and ultimately higher costs (not the least of those being the cost of hiring out of earth moving equipment, those guys charge an arm and a leg!).
Overall, except in a small number of cases, building reactors this way will often work out as more expensive and slower than just putting the containment dome above ground. But, as noted, it would potentially solve some safety issues.
10.3 Modular small and micro sized Reactors
One proposal that frequently surfaces is small batch production or even mass production of small or micro sized reactors. They would also be operated very differently from current “megatron” reactors. They could be used to supplement or “back up” renewables on small micro grids. Superior passive safety and smaller size would allow both “turnkey” capability and allow them to be build closer to towns and industrial parks, allowing for their use as heat sources as well as for electricity generation (i.e co-generation, overcoming the fact that 60-40% of the energy generated by a nuclear plant is thrown away as waste heat). If built sufficiently small, the supporters say, they could even be rendered “road mobile” and moved around the country as necessary. How realistic is this?
Firstly the reactors themselves, some small versions of the BWR or PWR (possibly a civilianised version of a navy reactor), or a small HTGR are obvious candidates. None of other reactors discussed wouldn’t be appropriate. The CANDU’s extensive piping network and needs for Heavy water rules it out (plus a number of other issues such as that positive void co-efficient), the LFTR won’t be a candidate either, due to its need for filtering plant and the exotic materials it would need to be made from, nor would the GcFR (as its primary role would be burning off of spent fuel it would be better building large to medium sized such reactors….fixed in place!).
Ironically, another “poor choice” of candidate is the IAEA’s proposed Generation IV reactor the modular lead cooled fast reactor. This reactor is remarkably similar to the BM-40A used on the Soviet Alfa class submarines of the cold war. The Alfa class was one of the best submarines the soviets ever built, small, capable of going much deeper than any Western boat, highly manoeuvrable and blisteringly fast – so fast and manoeuvrable that they could actually out run and out turn a number of allied torpedoes of the era!
However, the US navy Admirals slept quietly in their beds over the Alfa as it has two drawbacks, they were noisy (thus easily tracked) and it got this performance from its Lead-cooled reactor. The Lead had to be kept heated at above 125 °C or the core froze solid. In practical terms this meant keeping the reactor running 24/7 which made maintenance a nightmare. Of 7 Alfa class boats, 4 had problems with their cores freezing solid, in one case while the boat was at sea! For most of the boats this meant decommissioning and after it happened to the final boat in service, K-123, it seems that even the Soviet navy ran out of patience with the Lead-cooled reactor as they cut it out of the sub and replaced it with a standard PWR type.
While the developers of the LCFR claim to have solved this “freezing” core problem, the experience of the Russian navy suggests that this is not the sort of reactor we want to be putting in the hands of amateurs. Also, as it relies on running on highly enriched uranium, there are a number of potential proliferation issues which means we don’t want to be handing them out willy nilly… not without them drawing terrorists to them like moths to a flame!
10.3.2 – Turn-key capability
The above points regarding the LCFR of course raises the question as to whether any nuclear reactor can be designed with truly turn key capability, or indeed whether we even want to do that (on a practical and security conscious level). Currently the closest thing to anything nuclear with “turnkey” capability are radiation sources used by industry and hospitals, and there have already been a number of cases of such sources falling into the wrong hands, leading to serious contamination incidents (see the Goiania Incident or the Acerinox theft or a number of recent incidents involving “orphaned” Soviet RTG‘s) and several deaths.
And the truth is, as our society becomes more technologically advanced the number of products with true “turnkey” capability is growing rather small. Take your car, these days it’s likely to have more computers running it than the Apollo moon lander! Airlines are frequently wedded to aircraft manufacturers, who will regularly issue service bulletins, or have some of its own staff working permanently on site with major customers. And the primary “end users” of aircraft, pilots, are hardly lay-men!
So requiring our reactors to possess a level of capability that few rival products actually possess would be unfair. That said it’s certainly possible and desirable to reduce the level of dependence of new nuclear plant on a large body of highly paid staff, but inevitably some skilled and specially trained staff will always be required, at least so long as we want them run safely.
And besides which, sometimes the best way to make money on products is through after sales service contracts! Hence, manufacturers have little incentive to make true Turn-key capable products….indeed they have every incentive to do the opposite!
One of the other advantages of small or micro sized reactors, the ability to provide power for micro grids, may not be all its cracked up to be. In many cases a combination of renewables backed up by biomass fuel, or fossil fuels often works out cheaper and more practical.
One example often sited for these modular reactors is remote Artic stations and military bases. However, putting a reactor here ignores certain realties, notably that such sites are usually only occupied for part of the year. Artic stations often shut down over the winter with most of the serious scientists going home. The rest of the year a small skeleton crew keeps things running and basically keep digging the place out of the snow. By keeping a reactor on site we greatly increase the size of this skeleton crew (even a turnkey reactor needs someone to look after it!). Once you factor in the increased costs imposed by this, plus the higher capital costs of the nuclear plant to begin with, plus the difficulty of getting it and many tons of concrete (to provide radiation shielding) out to the middle of a wilderness, you realise it would be much cheaper just sticking with a diesel generator and shipping in the fuel.
Indeed even the DEW line radar sites which operated from the 1950’s to 1990’s year round deep within the Canadian Artic, were powered by diesel generators. The idea of nuclear power was indeed floated, but dropped as impractical and too costly. As far as active military bases, there is the tactical issue of shipping the reactors in (if I were the enemy I know when I’d chose to attack!) plus the small matter of running or refuelling a nuclear reactor while under fire from incoming artillery!
Of course there are some situations where a small or micro reactor could work out quite well, some small artic towns (that are occupied year around) and a few isolated spots in the steppes of North America and Central Asia, but we are talking a tiny niche market here.
10.3.4 – Co-generation with small reactors
Putting reactors closer to towns or at the very least industrial parks would certainly be useful. But it would require a major shift in public opinion. It was once commented to me by a supporter of nuclear energy that the best place in Britain to site a new nuclear power station would be on the same site as the old coal fired Battersea power plant right in the heart of London!
If you think about it from a technical point of view he’s absolutely right. Transmission losses would be practically zero, you could use the heat from the reactor to meet much of London’s winter heating needs and you could be guaranteed that the politicians down the river in Westminster would never go all penny pinching on the reactor and cut back on expenses as regards safety!
Of course from a political point of view, it’s a crazy idea. You’d have every woolly eared NIMBY in London coming out of the woodwork to oppose it. Unfortunately, like windfarms, everybody wants nuclear power stations (or geological storage facilities) in someone else’s backyard. The only exception to the above being certain communities where nuclear is a large employer, but often these aren’t the best places to put new industrial kit, nor housing estates.
10.3.5 – Convoy!
As regards putting reactors on the back of lorries and moving them around the country, that would also require a significant shift in public opinion, which I don’t see happening any time soon. Also there are the practical issues. Obviously such a road convoy would need to be conducted safely, so as to prevent a simple road crash creating a major radiological disaster. It would be difficult to see how this could be cheaper than shipping diesel generators around, or indeed renewable systems.
I also doubt whether you could ever get a self contained nuclear reactor onto the back of a lorry, at least a reactor that’s of some practical use at the other end. Bear in mind, that its not just an issue of volume, but also weight. The bridges on most “B” roads in the UK (and many of the A roads too) are designed for a maximum vehicle weight of 60 tons or less, and many smaller roads have even lower weight limits (under 15 tons). This would restrict a heavy single trailer reactor (as shown below) to travel on a handful of major “A” roads and motorways, which would probably have to be closed off for it to use them, and such roads rarely travel through locations where the electrical/heat load it is meant to satisfy would be located.
Then there’s the matter of shielding, i.e. the containment dome. It would probably be more practical to build that on site, though with a small reactor it wouldn’t be terribly large and could probably be put up by local building contractors reasonably quickly (so long as the reactor has a good, proven “passively safe” capability). In all likelihood you’d be spreading the power plant out over several trucks, so it’s more a sort of “nuclear circus” than a single 18 wheeler. Even so, I’m not sure how useful this would be. Most power demand in the sort of range than these modular micro-nuclear plants are pitched at are often more or less permanent installations. In such a situation, it would be more sensible in economic terms to just build a permanent power source (nuclear, fossil fuel, renewable, which ever works out best) on site, than stringing something together with a portable power station.
10.3.6 – The life atomic
Of course the most obvious use for a portable reactor is to power a ship. As with our artic bases, the extra crewing costs of nuclear combined with the higher capital costs of ship’s construction have often outweighted any benefits, except where performance is an issue, as would be the case for Arctic Icebreakers or nuclear powered warships. The size of the reactor can also leads to a reduction in cargo carrying capacity. While these conditions may change in the future, particularly if a cheap, compact and reliable nuclear reactor becomes available, but again the scope is likely to be fairly limited in scale (in global terms). And again, public acceptance would need to be forthcoming.
10.3.7 – Construction projects
There is some scope for using these “micro” reactors in construction projects, which often require power and heat in remote off grid locations (oil drillers for example, or ironically renewable energy projects!). But often the power demand varies depending on the project, meaning you need a range of reactors of different sizes. Building reactors this small, worse a range of smaller reactors, is going to be difficult to do on an economic basis. Also there is, again, the issue of supervision. It’s a lot easier (and thus cheaper) to train someone how to use a diesel generator, than how to use a nuclear reactor, even a “Turnkey” one! Also, as such sites move around frequently, moving our “nuclear circus” around would inevitably work out much more expensive than a simple diesel generator, even after we factor in fuel costs and future fuel price hikes.
Also, as anyone who has ever driven through road works late at night will know, rarely do such projects operate on a 24/7 basis, often just 9 to 5 on weekdays (yet they still make you do 30 mph!). There is little point in bringing in a nuclear reactor that’s designed to operate 90% of the year when its only needed 23% of the time!
So while there is some market for portable nuclear reactors, it’s unlikely to be huge. Given the development costs likely associated with such a reactor (especially if we want something with a reasonable “turnkey” capability) it’s difficult to say whether there is enough of a demand to warrant such an investment. Now I could be wrong in saying that and in the future some bright business person manages to make a small fortune with modular reactors meeting the niche energy markets they could supply (but it would be a risky investment strategy), but it won’t hugely change the global energy outlook given that you’d be talking about less than 1% of global energy use at most.
10.4 Mass producing reactors
One solution to the above would be if we mass produced reactors and started running them off a production line by the hundreds or even thousands. It is worth remembering that the whole reason why renewables is now on the verge of pulling ahead of nuclear is that they can be readily mass produced. If the Germans can get to the stage where they are running PV panels off the production line like sausages (and fuel cells to back everything up during the night) then they’ll have the French nuclear industry out of business very quickly. So in the longer term if nuclear is to keep up it’s got to start mass production.
Mass producing any product means keeping things as simple as possible, as Kelly Johnson once put it “keep it simple, stupid” . Hence again we can rule out all the reactor types mentioned other than a few Light water types and possibly some form of miniature Gas cooled reactor. Ideally such reactors should be made of as simple materials as possible, with the minimum of parts and assembly stages.
10.4.1 Design for manufacture
A good case study of how we Design for Manufacture (DfM) of complex products would be how the aviation industry batch produces jet airliners.
Ever notice how the standard jet airliner designs all look almost the same? with lightly swept back wings, 2 or 4 large turbofan engines hung under the wings, a near identical width-to-wing ratio for the fuselage dimensions, and a tricycle landing gear. This has been the standard configuration of a wide bodied jet airliner for the past 40 years with little significant variation, aside from the electronics (which have changed considerably over the last few decades).
Go on any aviation enthusiasts blogs and you’ll occasionally hear the question floated as to why certain design variations aren’t implemented. Putting the engines above the wings for example would allow use of the Coanda Effect allowing for shorter take off and landing runs, as the A-72 already is capable of doing. More heavily swept back wings would allow a faster cruising speeds, as the Sonic Cruiser proposed, the use of composites would also reduce fuel consumption plus allow for higher speeds. Radical designs such as the Blended Wing Body would produce greater overall performance, higher carrying capacity and a more spacious interior.
However, all of the proposals I’ve just listed off ignore the simple fact the modern jet airliner design represents a compromise between performance and ease of manufacturing. Most of the proposals above would be much more expensive to produce, awkward for the airline companies to use (imagine trying to park the plane shown above at a congested JFK!) and thus less economically viable.
Take materials for example. By and large the dominant weapon of choice of the airline industry for 50 years straight has been Duralumin, an alloy of Aluminium. This is despite major advances in composites such as Fibreglass over the last 40 years. Building large objects out of composites is something we’ve been doing since the late 1970’s, when the British introduced a minesweeper class of ships with GRP (Glass Reinforced Plastic) hulls. Bikes made of composites have been available since the 90’s and they are pretty much the standard material choice for yachts and even surf boards since the 90’s too. So why has it taken so long for the airline industry, who are normally at the cutting edge of technology, to jump on the composites band wagon?Again, cost and ease of manufacture are the simple answers.
While the new Dreamliner and its Airbus competitor (the A350) will use substantial amounts of Composites, 80% by volume for the Dreamliner, its interesting to note that by weight they’ll still be largely using metals (50% by weight is composite, probably representing non-structural parts, such as the wing and fuselage outer surfaces, the important load baring sections are still likely made of metal). Indeed if it weren’t for the ferocious rivalry between these two companies, and the heavy subsidies both receive from governments, I doubt they otherwise would be using any material other than Duralumin, as indeed the other leading manufacturers of aircraft are still sticking too. So it’s important to realise the necessity of “dumbing down” any design if we want to build it in very large quantities. Of course, this means compromising on performance.
10.4.2 – Design for Manufacture, the HTGR
To take a case study, let’s look at those HTGR and try and prepare one for mass production. Firstly I’d recommend dropping the core temperature down to 650 °C. We’d still likely require at least a Nickel alloy lining of the core, but the outer casing of the pressure vessel and the turbogenerator kit can now be made out of Stainless steel alloys. We would of course be sacrificing superior energy efficiency and the ability to make hydrogen thermally, but this drop in core temperature would solve so many problems it would be worth it. I’d also recommend shrinking it in size to around 20 – 40 MWth, that way we end up with a pressure vessel that’s easily forged or cast and yet still light enough to be moved around by a small crane and hoist system and that is also easily road or rail transportable (I’ll admit to WEG’ing it on that point though!).
I’d also probably ditch the whole “pebble bed” idea, as the mechanics of that while not impossible to mass produce “complicate things” and could lead to maintenance issues further down the line. Again, that graphite core, I would also investigate whether some alternative to that can be used, ideally something easier to dispose of afterwards and less of a fire hazard. I’d also likely drop any ideas about using Thorium, at least until any market for it, and the technology to make it work, have both been firmly proven. Another idea is to reduce the connections from core to any turbogenerator system, possibly by running on an open cycle directly connected to the core (see the GT-MHR for an idea about what I’m talking about).
10.4.3 – Design for Manufacture, the LWR
In another example we could take an off the shelf naval BWR or PWR reactor and civilianise it. Firstly, we’d need to ditch the highly enriched fuel and use something less “terrorist friendly”. We’d also need to beef up safety systems, ideally make the core capable of cooling by natural convection and fit some form of last ditch Boric acid injection system to shutdown reactions in an emergency. The individual parts of the reactor would likely need to be redesigned for mass production.
A good example of such a small modular LW reactor is the Babcock & Wilcox 125 MW Mpower reactor. This is a “small” modular PWR with a host of passive safety features. I would note however, that the idea of 60 fuel storage in proximity to the core might not survive past the post-Fukushima safety reviews and the problems of underground construction I’ve already addressed. I also suspect that it would be a little too big to be easily mass produced. Even so, it gives you an idea for the sort of reactor I’m proposing.
10.4.4 – Design for Manufacture, the implications
Looking at the two proposals above it is clear that in all likelihood the mass production of small reactors would result in a reactor design that is less energy efficient and thus burns more fuel per kWh than current reactors. So if we planned on using these to replace our existing nuclear capacity, we’d be increasing the burn up rate of our global fuel stocks, and increasing the amount of nuclear waste being generated. So we just made a failing grade on two of our important criteria!
10.4.5 – The dark arts of mass production
But the key question is, could we mass produce nuclear reactors cheaply? Could we run them off by the thousands and keep pace with renewables? Tricky! Mass production of any product is always a black art. What it amounts to is spending a large amount of capital on your production plant and design process with the goal of reducing the overall unit cost.
Imagine we are currently building a particular product for $1 million each. We spend $50 million on a mass production facility, plus a further $100 million designing the product for mass production, such that we can build each unit for a cost of $300,000…..but a share of that $150m must come from each product sold. We’d need to sell around 215 units before we’d be breaking even. If we sold 500, and lowered the price to $750,000 we’d still be raking it in….but if we only sold 200 units we’d make a loss, more so if we foolishly lowered the sales price below $1m before proving there was a market out there. Equally in order to sell at a price of $1m (or $0.75m) we’d need to prove that a market for several hundred units at this price existed. Another pitfall is if our R&D costs or the plant construction costs turn out to be higher than we’ve estimated. If they worked out as double our original estimate, than even with the 500 unit sales case, we’d still lose money. Then there’s other issues, notably materials costs can unexpectedly go up, as can labour, transport or energy costs. If they rise, the production cost of each unit rises too (as does the minimum number of units to break even), but we may not be able to raise the price to compensate for fear of reducing sales volume. And it is unlikely we’d find any of this out until after production has already started.
It is not unheard of in many cases of mass produced products for the company bean counters to do the sums after the product has already been on sale for some time and work out that the firm is loosing money on every unit sold! I’m told that this happens all the time in the car industry, which has been mass producing products for a good century! If they can screw it up you can imagine how easy it would be for our nuclear reactor production to do the same. And making a loss with mass production is worse than individually sold reactors as it means any losses are multiplied by a factor of hundreds or thousands (i.e. each unit sold!).
This is the problem with mass production; you are multiplying your mistakes many times over, so you need to get it right first time. If you make a tiny flaw in the design, that flaw gets repeated and made hundreds of times over, before you actually notice it. The end result is either a lot of scrap metal or a messy product recall that will drastically undermine your customer’s confidence in you as a supplier and hurt sales. This is why it’s crucial to iron out any design issues at the development stage, not when you’re building 10 units a day! Of course, more careful design means higher development costs, which again gets deducted from every unit sold.
Another problem with mass production is start up problems. Almost every product has some production problems when mass production starts. I once worked for an electronics company and was surprised to learn that 50% of our new product was failing or being scraped at various points in the process. This was considered perfectly normal! The one small stage we were overseeing was seeing a failure rate of +20% due to a small change we’d made in the manufacturing method! Of course as diligent engineers we soon cut that down to less than 2%, with commensurate drops by our colleagues at other production stages over the preceding year. But if we’re talking about nuclear reactors rather than mobile phones or laptops, that’s an awful lot of scrap metal to be throwing away. Worse, as the consequences of a “dud” reactor being loaded with fuel and turned on are unthinkable, we’d need to enforce a strict (and expensive) system of inspection of said reactors to ensure no “duds” leave the factory.
Weighing all these factors up should tell you that developing a small or micro reactor capable of mass production, isn’t going to be easy and would be expensive. It is difficult to see whether this expense would be justified, given the likely small market for such reactors.
10.4.6 – Small batch production
An alternative is so-called batch production of products. Here you use many of the techniques of mass production, just on a lower volume scale, which reduces the financial risks somewhat. This is already being performed with reactors such as the French EPR. However, Batch production suffers from many of the above problems, notably all you’re R&D plus manufacturing infrastructure costs have to be deducted from each unit sold. If they are too high, or you simply don’t sell enough units, you make a loss, although not as much of a loss as with a higher volume mass production process. Equally though by building on a smaller scale the “volume gain” is much smaller, as you are producing much less units and the price reduction (if any) is smaller.
10.4.7 Don’t forget the dome!
Finally in the case of nuclear, don’t forget that big (or small) concrete containment vessel. Those would inevitably have to be built on site and most of the recent problems with nuclear construction, in terms of delays and cost overruns, have been in the construction of those. So mass production isn’t really going to help solve that bottle neck.
While there is some scope for “mass producing” reactors, it’s not nearly a possibility on the scale the supporters of nuclear energy suggest, at least not in the short term anyway. Worse still, in order to make any reactor capable of being mass produced it would be necessary to essentially “dumb it down” meaning poorer thermal efficiency and a higher rate of fuel burn up and ultimately a greater volume of nuclear waste generated. While safety and flexibility would be improved, we’d be paying for it!