To the Editor, Physics Today,

Responses in the November 2004 issue to the July articles on energy and population seem to fall into two main categories: those who believe the population problem is already solved through declining birth rates, and those who believe the energy problem is already solved because we have nuclear power and continuing energy efficiency improvements. Both of these views are falsely optimistic and minimize the tremendous technology development problem we have ahead of us, to provide sufficient energy for a prosperous world in the 21st century and beyond.

On population: even with the most dramatic conceivable drop in birth rate, the only way population will decrease sufficiently in coming decades to make much difference to the energy question is with a correspondingly dramatic increase in death rate. I am surprised so many physicists seem willing to accept this option.

Nuclear energy has 4 basic obstacles that may prevent it from ever being scaled up by the factor of 20-50 needed to address world energy needs: cost, incompetence, corruption, and waste. No breeder reactor, a technology necessary for nuclear fission to be a long term solution, has ever been successful in the marketplace. Due to the enormous energy content at each plant, staff incompetence can lead to much more serious disasters than for other energy sources, even for reactors billed as "inherently safe". A world filled with breeder reactors would necessarily include large-scale traffic in plutonium; just one criminal in the supply chain could trigger a nuclear holocaust. And the long-lived accumulative character of nuclear waste justifiably frightens many educated members of the public. Billions have been spent on nuclear energy research, with little progress on resolving any of these issues at the scale that would be needed.

Energy efficiency improvements can only slightly mitigate the continued growth in world energy demand, as developing countries advance. The energy problem we face is an immense one - trillions of dollars of energy infrastructure will need to be replaced, in coming decades, with alternatives of one sort or another. All the renewable energy options face cost issues both in production and in transmission and storage of energy that put them out of reach of large-scale deployment, without significant research investment to bring those costs lower. This is a problem on the scale of the Cold War, but we are not treating it as such. It is past time that the US Secretary of Energy was given the same respect, if not the same budget, as the Secretary of Defense, and charged with resolving this critical problem for the nation and the world.

Nobel Chemist Richard Smalley has been speaking on the energy problem around the country; I heard him recently at Brookhaven National Lab. His specific suggestion is a "nickel and dime" solution: a 5 cent/gallon gasoline tax and perhaps similar carbon taxes on other fossil fuels, to raise about $10 billion/year for alternative energy research. That's the scale we need, not the miserly $80 million solar energy gets in the current US budget. And we need physicists and engineers to energetically tackle the critical problems, just as they did 60 years ago for the Manhattan project. Every year of delay in developing these alternatives further threatens the future well-being of humanity.

Arthur Smith

Comments

On Bartlett's response Written by apsmith on 2005-03-31 05:00:24 Both original writers seem to agree with me for the most part - Weisz claims the problem is even more severe than that faced for the Manhattan project, which may well be true.    Bartlett, however, questions my assertion that population will not decrease sufficiently without a dramatic rise in death rate, quoting stable populations in European countries. But that's exactly my point: a stable population is not a declining one, and there are very few nations that have seen an actual population decline in recent years not caused by a rising death rate. To meet the world's energy needs - i.e. providing enough energy for a moderately civilized life, requires either greatly increasing world energy production, or greatly reducing world population, by factors of 2 or more, by 2050 or so. No natural decline caused by declining birth rates can make that happen.

Smith persists ... Written by GRLCowan on 2005-03-31 17:18:27 in his unsupported expression of belief that risk cannot be significantly out of proportion to available energy content. The volatile chemicals that did fuel-air explosion at BP's refinery recently, killing at least 15, have, when condensed, less potential oxidation energy per litre than does solid aluminum. I don't have to know which organics they were to know this, for it's true for every organic compound, even solid cubane.    Similarly, reactor physics and decades of experience concur that fission reactor cores able to deliver thermal gigawatt-years on demand have less severe thousand-year accidents than, for instance, fuel tanker trucks able to deliver gigawatt-hours.

persists? Written by apsmith on 2005-03-31 22:56:20 I'm not sure where I've said it elsewhere before... comparing vaporized chemicals in an oil refinery with solid aluminum is a rather extreme example: nevertheless aluminum powder can also explode in the right circumstances - see this MSDS: http://www.jtbaker.com/msds/englishhtml/A2712.htm  we just don't normally use it that way.    You claim my "expression of belief" is unsupported - well it's supported at least by logic that, all else being equal, certainly implies accident potential proportionality to energy content. Much of the energy content of a fission reactor is not released in the fission (explosive or normal), but remains in the radioactive fission byproducts, whose release is of great and valid concern to the world (I'll mention Chernobyl, but it's not the only example).    Do you have any support for the belief that "thousand-year accidents" for fission reactors are less severe than those for fuel tanker trucks, measured on equal terms (a few thousand fuel trucks = 1 reactor?).    Or if terrorists gained control of (and were able to reprocess for plutonium etc.) the contents of a single reactor core, could they do more or less damage than with a comparable bunch of fuel trucks?

Table link Written by GRLCowan on 2005-04-02 16:22:58 "Supported at least by logic that, all else being equal, certainly implies accident potential proportionality to energy content"? Well yes: if all else is equal, then all else is equal.     Smith uses an MSDS to argue that aluminum can be dangerous. He should see the MSDS for neutral saline. But the contention is true; people have been hurt in lab demos with powdered aluminum and liquid oxygen, and misbehaviour by an aluminum/ammonium perchlorate combustor figured centrally in the first Shuttle disaster.    The contention is true, but not to the point. Aluminum can be dangerous, but it can also be safe. In normal use 3-ethyl-3-methylpentane, or whatever similar thing it was that most recently blew up Texas City, isn't explosive either, but the ease of avoiding abnormal conditions allowing runaway oxidation differs very much between it and aluminum, and the direction of the difference is such that greater energy concentration -- a darker cell on this chart -- is safer.    I'm not sure anyone but Smith and me is reading this, so maybe this would be a good time to check whether we're getting anywhere. Does Smith acknowledge any fault in supporting his proportionality assertion with its reassertion in different words?    --- Graham Cowan, former hydrogen fan  boron: how individual mobility gains nuclear cachet

sure (and any lurkers out there?) Written by apsmith on 2005-04-02 19:56:05 There is certainly no strict proportionality between energy density and risk, I would agree. Nice web page on boron etc. by the way!    In the case of boron and aluminum, there are certainly chemical details that matter - the solidity of the oxides protects the energy content of the solid metals. Starting with a solid material in the first place helps - our asphalt roads are full of combustible hydrocarbons, but rarely catch fire. Material details do matter.    Nevertheless, given the energy content, there are always pathways to releasing it, and rarer pathways to rapid release. They may have large barriers under normal circumstances, sure. But given such a pathway's existence, it's impossible to guarantee that the normal barriers cannot, under deliberate or accidental circumstances, be breached.    It was the high energy content of the jet aircraft on 9-11 that made them such attractive targets and destructive weapons. The enormous energy content of a nuclear reactor likewise makes it an attractive target for those who wish to be destructive. Even small research reactors these days have armed guards.    The point is, we're not talking about mere factors of 10 here in energy content levels - your chart compared chemcial fuels that were all pretty much within a factor of 2 or so of each other. With nuclear fuels, the energy content is on the order of millions or billions of times greater - 1 cu. ft of uranium for example has the same energy content as 32 billion cu. ft of natural gas! So even if there is a factor of 10 or even 1000 due to natural barriers to that energy release, the likely risks are still extraordinarily high for fission reactors.

32 billion volumes ... Written by GRLCowan on 2005-04-03 02:04:20 seems about right, if the 235/238 business can be ignored, and also the volume of stoichiometric air for the gas.    But this is an argument for steering very wide of rocks, in case they might be ornamental tiling stone storing, with respect to fission, the energy that a million times their volume in maximally explosive gas-air mixture might release in exploding. Any boulder could create another Ghislenghien, at any moment.    And what if the natural barriers are a trillion times greater, not just 1,000? Might this not make more sense, in light of our experience of getting through fission, so far, 180 EJ of electricity -- 500,000 cubic km of gas worth, 5 million km^3 of gas-air mix -- with, as far as I know, just four associated runaway-fission accidents? (SL-1, Chernobyl, Tokai-Mura, NRX.)    Rather than reasoning that while risks associated with runaway energy release can be a little decoupled from stored energy density they surely-to-goodness can't be a lot decoupled -- do you cringe when the Sun comes up? -- consider the late Edward Teller -- whom I like to compare to Gandalf -- and his Reactor Safety Council.    They put their minds to playing devil's advocate in a disciplined way, not just saying, "There's got to be some way to blow that thing up", but finding it. They learned the lessons of Chernobyl in 1950. (The NRX story shows we in Canada didn't get it until 1952, and not entirely just by thinking on the matter, although the reactor was repaired.)    Thank you for noticing my web page. What do you think of the negative feedback mechanisms I note, with a reference, here?      --- Graham Cowan  boron: how individual mobility gains nuclear cachet

Correction, 14,000 km^3 Written by GRLCowan on 2005-04-03 05:19:28 of natural gas, not 500,000.

Link correction Written by GRLCowan on 2005-04-03 14:47:28 The textbook chapter linked from my SciScoop comment can now be found at http://book.nc.chalmers.se/KAPITEL/CH19NY3.PDF

ways to blow things up Written by apsmith on 2005-04-05 04:43:37 I'm not sure what "learned the lessons of Chernobyl in 1950" signifies - other than avoiding carbon as a moderator... Have you ever visited the Hanford site? I have. It's a scary place, especially after you talk to the people who work there (I was with the environmental sciences group briefly).    Only 4 "runaway fission accidents"? What about Three Mile Island?! This site lists 8 events:  http://www.nucleartourist.com/events/part-melt.htm  from 1951 to 1979, so not including Chernobyl or Tokai-Mura. There were 35 immediate fatalities at Windscale, as at Chernobyl. Not included on this list also are the dozens of reactor accidents that have occurred aboard nuclear submarines.    Perhaps those seem like relatively few accidents anyway, for 180 EJ of energy - although I think most people realize none of these accidents was really a "worst case". But we have also used something like 10,000 EJ of chemical fuels in the past 50 years - which side has killed or injured more people per EJ? It may of course depend how you count - if you count those killed in coal mining accidents, you probably also should count (at some level) those whose lives were shortened by exposure to radiation in uranium mining - which I've been told adds up to significantly more damage than the accident totals (so far).    On negative feedback - sure that exists; the basic problem of reactor physics is maintaining an exquisite balance between the positive and negative feedbacks so that a reaction proceeds at a steady rate. We're not leaving the uranium sitting in rocks, after all, we're actually trying to extract substantial quantities of energy from it, and that's where the danger lies - our interference, not the intrinsic danger of the materials on their own.    And was Teller more like Gandalf, or Saruman?

Against that power, there can be no vict Written by GRLCowan on 2005-04-06 12:17:32 Doesn't sound like Teller to me. Teller was more like Gandalf. If he was right in questioning Oppenheimer's judgment, that would make Oppenheimer, near as I can guess, correspond to the Steward of Gondor. I don't know who, if anyone, was like Saruman.    If your Prius loses power and you have to push it along a level road, do you believe an"exquisite balance" will exist between your pushing it and its drag? How about the Oklo reactor? Was that, as it lay untended in the ground, in exquisite balance? What positive feedbacks do you see working in it?    "Exquisite balance" suggests a marble perched on a beach ball, not, as fairly represents the case of fission reactors that get less reactive as they get hotter, a marble at the bottom of a bowl.    --- Graham Cowan, former hydrogen fan  how individual mobility gains nuclear cachet

positive feedbacks Written by apsmith on 2005-04-13 21:30:44 If there were no "positive" force here, Oklo would not have fissioned any material at all (beyond the natural isolated Uranium rate). What happens in a commercial reactor is the balance between the chain reaction (associated with number of slow neutrons available and material geometry and density) and the negative feedbacks is adjusted to increase the fission rate from that of isolated uranium to something commercially useful. One hopes the design ensures that this balance does not get out of hand, but it's only "a marble at the bottom of a bowl" if you neglect half the variables in the picture (the ones that we humans are using to increase the reaction rate, variables that were not present at Oklo).

Smith seems not to understand the term " Written by GRLCowan on 2005-04-15 18:36:18 Witness his use of it as a heading followed in the text by the switch to variables and positive force, with positive in quotes.    I see the principal difference, fission kinetics-wise, between an Oklo reactor in a starting-up state and a man-made BWR in that same state as the amount of water flow. When shut down, an Oklo reactor was watered only by the slow influx of groundwater; eventually its increasing water content would send it supercritical, i.e. turn it on.     Kinetically it would then be just like a man-made BWR to which just enough control rod withdrawal has been done to make it supercritical.    The addition of moderator at Oklo and the removal of poison from the BWR are both, to use Smith's term, positive forces. But neither is a feedback, because both are external. Feedback is what a system that one wants to control does to control itself. When a car's accelerator pedal pushes back on the driver's foot, that's a negative feedback: the driver must overcome the car's tendency to reduce its own power.    If, however, it were set up to push back only through part of its travel, and beyond that to pull away from the driver's foot, the pulling-away part of its range would be the domain of positive feedback.    From the "natural isolated uranium rate" of fission both supercritical reactors now will slowly speed up. At first, with watts or milliwatts of power, this won't significantly change the temperature of the water, nor of the fuel and the neutrons that are in thermal equilibrium with it. If no more groundwater comes and no more poison-rod withdrawal is done, both powers will continue to rise at a steady several percent per minute or per hour. Eventually, though, the temperature will rise significantly, and this is where the accumulating effects of supercriticality will begin to affect supercriticality: it will begin, indirectly, to brake itself.    If supercriticality's accumulated effects were to increase supercriticality, that would be it "feeding back on itself", hence the term. But self-braking is also a feedback, a negative one, and obviously it is the useful kind, like the sprung resistance of a car's gas pedal. Negative feedback is a positive good.    I see three shared negative feedbacks between Oklo and a modern BWR. One, hotter neutrons are more likely to escape a reactor, and so end the fission chains they might otherwise have participated in. Two, they are less likely to avoid capture by uranium-238 and find their way to a 235-U nucleus; this is the Doppler broadening mentioned on p. 15 of http://book.nc.chalmers.se/KAPITEL/CH19NY3.PDF.    Three, the water eventually begins to evaporate, and as there gets to be less of it, neutrons are not so effectively thermalized, and their tendency to escape or be captured in ways that do not extend fission chains is further increased. So again, supercriticality is reduced. When it gets to zero, the reactor is critical: power neither rises nor falls.    By providing lots of broad channels for water to flow through, and anchoring the fuel securely, the purpose-made boiling-water reactor settles on the same equilibrium that Oklo oscillated around, but at a higher power level. Neutronically, nothing else seems much different to me.    Moreover, despite repeated assertions that the man-made system is not at the stable equilibrium that one would think its designers would diligently seek, and the Oklo reactors seem naturally to have more-or-less found, because in believing it to be there I have neglected "half the variables", Smith does not identify any of these variables.    This leaves him with little right to condemn critics of his preferred powerplant, the solar power satellite, when they talk about stray gigawatts of microwaves wandering the landscape, dropping birds in flight, making instant volcanoes. Who said mere criticism had to be numerate, or take any interest in details?    (It wasn't carbon reactors per se that Teller discontinued; several excellent reactors have been full of carbon, including at least one of those that have been put through the "Stop coolant flow at full power and walk away stunt". It is the combination of carbon and light water in the same core that Teller put a stop to, so that nowhere outside the former Soviet Union was the chance of a Chernobyl ever taken. Fatalities at Windscale numbered zero, not 35. Residual beta-radioactivity, not runaway fission, wrecked the Three Mile Island reactor, and some others, but only runaway fission has ever hurt anyone, and today's Oklo-style reactors can't do it. Details ...)    --- Graham Cowan, former hydrogen fanboron: how individual mobility gains nuclear cachet

"Feedback" concept not got Written by GRLCowan on 2005-04-16 14:33:07 Mighty short titles allowed here.    --- Graham Cowan  how individual mobility gains nuclear cachet

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