Talk:Clean and Environmentally Safe Advanced Reactor

Supercritical Water Reactor ?
I don't think it is complete pseudophysics, because there seem to be similarities with the Supercritical Water Reactor, SCWR, a Generation-IV reactor concept. However, I am not a nuclear scientist and I feel uncomfortable discussing the similarities and differences between the CAESAR and SCWR concepts in the article.

Coenen (talk) 21:38, 10 February 2011 (UTC)

Potential pseudophysics
This is an interisting concept. So... basically this is a epithermal/fast reactor that is cooled and moderated by steam? I am unclear as to how the heat transfer system and fuel are set up. Is the fuel pure U-238 metal in a steam environment, or is there cladding? Is the thermal-hydralic system refered to in the article present to capture waste heat like the material with a large heat capacity that is used in Sterling engines to capture heat? I think I interpreted enough of the original sources info, but it sounds a lot like an adveritsemnt for more funding... other sources for steam moderated power plants would be good to back this up. Lcolson 07:55, 12 February 2006 (UTC)


 * This looks like Pseudophysics. First, slowing down neutrons is a random process.  A certain depth of moderator will slow down some neutrons all the way to thermal speed, leave some at the original velocity, and others at intermediate speeds.  Second, there is no exactly right speed to split U-238.  See the graph for "Neutron Cross-Sections for Fission in Uranium and Plutonium" in http://www.uic.com.au/uicphys.htm.  U-238 has a broad curve starting above 1Mev, with increasing cross section with increasing energy.  The faster the neutron, the higher probability of U-238 fissioning.  I don't have an online source for this, but in "Megawatts and Megatons" by Garwin and Charpak, the capture cross section for U-238 goes down monotonically at all energies above 104 ev. If U-238 could sustain a chain reaction, pure unmoderated U-238 would be best, but it is well known that it does not.


 * As for Carnot efficiency, it is limited by the highest temperatures that the materials can stand. To get 68%, the temperature would have to be 660 degrees C.  If conventional fuel rods could tolerate this temperature in the presence of steam, then conventional plants would do this.


 * Therefore I am labeling this as Pseudophysics. For more wacky stuff, see . pstudier 22:55, 1 March 2006 (UTC)


 * So the A James Clark School of Engineering at University of Maryland is harbouring cranks? I really don't that much about US schools - is this some questionable institution? If so and if this is nonsense I will be the first to put it up for deletion (even though I started the article) B.S. can baffle brains if it is served up right (in the shot term at least). --DV8 2XL 23:39, 1 March 2006 (UTC)


 * Don't know about harboring cranks, nor do I know anything about this university. Maybe he brings enough funding to justify keeping him. Here is another article from 1998 with a wacky scheme Putting Nuclear Waste to Work.  If he wasn't a crack pot, then he would be very rich and famous with this invention.  I think we should keep the article because he has had enough press coverage to be sufficiently notorious. If we delete, then the conspiracy nuts will scream that we are suppressing this invention. pstudier 00:13, 2 March 2006 (UTC)


 * I don't really see how any of your points show this to be pseudophysics. It's a little disturbing that I can't find much of anything published on this, but I rather trust the Economist to identify total cranks.  And the University of Maryland is no research powerhouse (in my field at least), but it's certainly not going to keep around any pseudoscientists.
 * The description of how it works could be improved, but I definitely support removing the pseudophysics label unless anyone can provide some information pointing that way. &mdash; Laura Scudder &#9742; 00:18, 2 March 2006 (UTC)


 * Let me simplify what I said. For fissioning U-238, the faster the neutron, the better.  So unmoderated is better.  It is well known that pure U-238 can not be used for either a reactor or a bomb, so this reactor concept can not work.  Finally, he has been at this stuff since 1998 and has never published anything about it in a peer reviewed journal. pstudier 00:32, 2 March 2006 (UTC)


 * While the article certainly has other problems, you can definitely adjust the average speed of neutrons by adjusting the moderator's density as described. The mean path length before interaction for a given cross-section should be more or less constant, meaning that changing the density changes the number of moderator scattering events before interaction. I've removed the "pseudophysics" tag, for this reason and reasons cited by other editors above. While the article and linked web pages contain hyperbole, they don't appear to claim anything actually impossible (I'd tentatively attribute the Carnot efficiency concerns to something being garbled between the researchers and the reporters, as opposed to an impossible claim being stated by the researchers; this tends to happen a lot). --Christopher Thomas 05:31, 2 March 2006 (UTC)

wow, I was prepared to treat it as any other plant design on Earth, but it would seem to be a bit different (crazier), oh well. -Theanphibian (talk • contribs) 02:08, 14 October 2007 (UTC)

Concerns about this article
While the article doesn't seem to describe anything technically impossible, I'm concerned that both the article and its references appear to use a very pro-nuclear tone, which I don't think is consistent with WP:NPOV. Also, as has been pointed out in the previous thread, there's a lack of links to bona fide peer-reviewed publications about this project and its predecessors, though with U of Maryland backing this it's not likely to be actual junk science. I strongly suggest that the article be rewritten to a short, neutral overview of what this reactor is, what its merits and drawbacks are, and a set of links to related concepts (fast breeders and so forth). It'll be about two months before I'm in a position to handle this myself, which is why I'm writing about it instead of going ahead and doing it. If it's still a problem in May, I'll take another look.--Christopher Thomas 05:36, 2 March 2006 (UTC)


 * I restored the pseudophysics category. From Nuclear fission:


 * Not all fissionable isotopes can sustain a chain reaction. For example, 238U, the most abundant form of uranium, is fissionable but not fissile: it undergoes induced fission when impacted by an energetic neutron with over 1 MeV of kinetic energy.  But the neutrons produced by 238U fission are not, themselves, energetic enough to induce further fissions in 238U, so no chain reaction is possible with that isotope.  Instead, bombarding 238U with slow neutrons causes it to absorb them (becoming 239U) and decay by beta emission to 239Pu. If this were not true, why would countries all over the world spend billions of dollars enriching uranium and prototyping breeder reactors if they could burn 238U? pstudier 22:02, 2 March 2006 (UTC)


 * This is a breeder reactor. I fully agree that the description as-given is somewhat mangled, and may include erroneous statements, but pseudoscience this is not. When run with steam at high density, it acts as a conventional thermal neutron reactor. When run with steam at low density, it acts as a gas-cooled fast breeder reactor. Most current and proposed FBRs are liquid-cooled, but gas-cooled ones have been proposed. I have doubts about a steam-based FBR being workable for practical reasons, but that doesn't make the project to study the idea pseudoscience. If you have a problem with specific claims in the article, how about editing the article, rather than dismissing the whole thing? Or backtracking sources to see where the claim came from? An article based on press releases reported by journalists _will_ contain serious technical problems, independent of the validity of the original source. --Christopher Thomas 22:19, 2 March 2006 (UTC)


 * From RESEARCH FRONTIERS AT THE UNIVERSITY OF MARYLAND, March 3, 2003, Vol. 4, No. 1, available on the University of Maryland Website :


 * “Right now,” he explains, “in every nuclear reactor in the world, there is a certain amount of nuclear fuel, which is mostly formed from a mixture of Uranium 238 and 235 moderated by water. U-235 is weapons-grade material, the material used to make bombs.  Without U-235 or an equivalent isotope (e.g., plutonium 239) a conventional civilian reactor is unable to sustain chain reactions, and thereby produce power.


 * There are normally two types of these neutrons: prompt and delayed. Prompt neutrons are too fast, delayed neutrons are too slow.  So in a nuclear reactor the prompt neutrons are slowed down by making them collide with water (the moderator).  Therefore the thickness of water between the rods is designed to slow down the neutrons to the optimum speed for fissioning U-238.  Unfortunately, the thickness of the water designed to slow down prompt neutrons and safely cool down the fuel rods is “lethal” to the less energetic delayed neutrons because, even if they manage to travel between the rods, the amount of water that they have to pass through slows them down so much that they have insufficient energy to fission U-238.  Therefore, the thickness of the moderator (water) and its heat transfer characteristics are crucial parameters in the design of a nuclear reactor.  But once the design of a reactor is completed, and the vessel containing the nuclear core is sealed, the ratio between water and fuel cannot be changed.  This is true for nuclear reactor designs anywhere in the world.


 * So it is clear that this is not a breeder but that it supposedly fissions U-238. pstudier 23:32, 2 March 2006 (UTC)

Rewrite
Got rid of some of the POV phrasing for a start and integrated the skepicism in to the main body of text. --DV8 2XL 01:58, 3 March 2006 (UTC)


 * Thank you, it is quite an improvement. pstudier 02:46, 3 March 2006 (UTC)


 * Agreed, though finding reputable literature containing skeptical commentary would be even nicer (just so all is are dotted and ts crossed). Journal papers, rather than newsletters, from the proponents would be ideal, but you've already looked for those.--Christopher Thomas 06:30, 3 March 2006 (UTC)

Still tagged as pseudophysics
I'm having trouble seeing why this is still tagged as pseudophysics. Dr. Filippone thinks it'll work, many others don't, no exotic physics is proposed, the jury is out until they test it, and tests are planned (eventually) by a reputable institution. Isn't this how science is supposed to work? If the device fails, and Dr. Filippone makes claims that it's because mainstream science is wrong about something rather than that he couldn't get high enough neutron economy, then sure, but to my knowledge he hasn't made any such claims yet. The worst I've seen is an unfortunate tendency to hyperbole in the project web page.--Christopher Thomas 06:55, 3 March 2006 (UTC)


 * A chain reaction with U-238 is terribly exotic, and does not work for reasons that I have already given. Besides, he has been doing this stuff since 1998, but apparently has never demonstrated a chain reaction nor published a paper in any journal. pstudier 07:15, 3 March 2006 (UTC)


 * As near as I can tell from the description you quoted and the project page, he's proposing that daughter products from induced fissioning of U238 produce enough neutrons (delayed neutrons) to keep fissioning U238, in a suitably designed reactor. I'm certainly _skeptical_ of this claim (I'd expect spent fuel rods to melt once removed from a normal reactor, for one thing), but I don't see how this can be ruled as pseudoscience unless someone actually demonstrates that the concept as-proposed can't possibly ever work, and he continues claiming that it does (paper demonstration would be fine, with good enough data on cross sections at various energies and species produced). Re. testing since 1998, I don't get the impression that Dr. Filippone has actually managed to test this under conditions that would conclusively prove him right or wrong (just much fooling with mock-ups of other parts of the system, and some testing with U of Maryland's experimental reactor, which is moderated by liquid water). His web page only lists very old publications. I've emailed him politely asking for CAESAR-related publication citations, and will post here when I get a response. If he hasn't gotten anything published, it does indeed bode ill for his credibility; we'll find out soon enough. --Christopher Thomas 07:33, 3 March 2006 (UTC)

Update: I've been extremely busy for the past few weeks, and will likely remain so. I didn't hear anything from Dr. Filippone regarding publications. I defer to your judgements regarding article content, as I'm not in a position to research it further at present. --Christopher Thomas 06:15, 22 March 2006 (UTC)

Some notes on Dr. Filippone

 * From here (for what it's worth):


 * "Claudio Filippone spent more than a year in a dispute with the University of Maryland over the patent status of his discovery, which would recycle used nuclear waste into fuel. "The inventor puts years into his work and the technology office gets a paycheck, no matter what," he says. "They never suffered for the technology but now they say that I owe them half of the work."


 * This shows that The College of Engineering of The University of Illinois Urbana-Champaign had him give a seminar on the topic last year.


 * The neutronics, as described by the Press, are a crock - no question.

HOWEVER

Considering what I see in this paper by Filippone, which deals with the thermodynamic aspects of this idea I have drawn the following tentative conclusions:


 * 1) The design of the reactor would use a film of steam on the fuel rods, not an all gas moderator, and this makes a little more sense.
 * 2) I suspect that he is not claiming to start or maintain fission in U-238, but use the increased neutron efficiency to do what CANDU's do right now with theirs and convert and burn more of the stuff through the standard reactor cycle of first converting it to Pu. The common Press being to lazy or stupid to describe it fully to their readers.
 * 3) What isn't clear is that it is my understanding that it is not the lack of neutrons that stops CANDU fuel from burning but the build up of neutron poisons that renders the fuel exausted.

--DV8 2XL 15:08, 3 March 2006 (UTC)


 * Note that Dr. Filippone is not currently associated with the University of Maryland and that the document you reference is not a refereed paper but a proposal from 1998.    As far as I can tell, the CAESAR concept has not been described in the regular scientific literature at all.    I believe that this article violates the spirit of the No_original_research rule and should be deleted.   I see no reason that the CAESAR concept should not be mentioned in a longer nuclear reactor article though.   Alison Chaiken 05:32, 5 March 2006 (UTC)


 * Alison, would you mind telling me how I have violated WP:NOR here? There is no novel interpretation or synthesis by me of this persons work; I have provided sources on the main article page that meet the terms of WP:V. I think that you might be confused about these policies and how they are applied here. --DV8 2XL 06:37, 5 March 2006 (UTC)


 * To pedantically quote the cited policy, "Original research is a term used on Wikipedia to refer to material added to articles by Wikipedia editors that has not been published already by a reputable source."   We can argue that the CAESAR concept has been "published" on a web page, but I believe that's not the type of publication the policy intends.    The links you have created point to popular articles written by journalists who don't have the ability to judge Filippone's contribution, not scientific publications by Filippone himself.


 * Perhaps I'm being too critical here.   After all WP has articles on all kinds of inanities like television shows and rock songs.    Nonetheless I take the physics articles personally and hope to hold them to a higher standard!   Alison Chaiken 07:34, 5 March 2006 (UTC)
 * I can certainly appreciate your thinking Alison, and yes we could both keep each other in stiches for an hour or so trading URL's to web pages with some very bizarre ideas claiming to be physics, however I came across this in the Economist and then found the University of Maryland website, and these seemed to give some weight to the idea. So at worse I'm a victim of McLuhan's ditum that "the medium is the message." This is why I asked up thread if we should take this to AfD.
 * I reacted strongly to your insinuation because what I had written at the top of this section would indeed draw a righteous charge of OR had I put it in the main article space; but to the best of my knowledge this policy has not been in force on the discussion pages.--DV8 2XL 18:06, 5 March 2006 (UTC)

I have been aware of Filippone claims for quite some time. I think that this makes CAESAR noteworthy enough for an article that includes the reasons to be skeptical. Just like N ray and Polywater. pstudier 06:22, 5 March 2006 (UTC)

A physically impossible reactor
I am new to this sort of thing, but I must admit that I find myself fascinated at the discussion about whether or not this is "real" or "psuedo" or something else; yet no one seems to have taken the time to contact someone who knows anything about how a nuclear reactor works to see if there's any substance to the inventor's claims. My credentials: a doctorate in fission reactor engineering from MIT and 25+ years experience in the nuclear industry. My conclusion: the so-called "CAESAR" concept is bogus. To call it psuedophysics is being kind; the physics governing nuclear reactors show that nuclear chain reactions cannot be sustained in U-238, as Filippone claims. Moreover, his assertion that he can somehow "tune" delayed neutrons to cause U-238 to fission is false. Delayed neutrons are "born" with energies less than 1 MeV, and as pointed out in an earlier comment, U-238 has a 1-MeV fission threshold.

If you stick U-238 in a stream of neutrons with less than 1-MeV, all you get is conversion of the uranium to something else--primarily Pu-239. That's how a breeder reactor works. But it does not change the fact that you can't run a reactor off of U-238.

By the way, I have challenged Dr. Filippone on several occasions to submit his work to a reputable technical journal for peer review. His former colleagues at the University of Maryland have made the same request. He refuses to do so. Draw your own conclusions on that. —Preceding unsigned comment added by Anuke (talk • contribs) on 05:28, 22 March 2006
 * Since this is your first entry to Wikipedia let me say welcome on everyone's behalf. It might come as surprise to you to find that the criteria for inclusion of a topic in this project are notability and verifiability - not truth. We have found it best not to take a high-handed approach to issues and claims, but to carefully report on a topic not giving it too much weight or too much criticism. Sorting through a subject like this requires that all of the editors examine the source material, and from it produce a balanced article. Filippone has some very vocal critics - doubtless you are one of them - however the users and editors here at Wikipedia would rather not see disputes like these spill into our pages. This is not to say you are not welcome to contribute, however this is not the place for a fight. --DV8 2XL 15:35, 22 March 2006 (UTC)
 * Well, I understand the rules and I admire your efforts to retain a certain objectivity, but science is a discipline that deals in truth, or at least, in facts--and provides a mechanism, the scientific method, for investigating claims and determining their validity. Not every argument has two "equal" sides, and "balance," in my view, is a virtue only when there is, in fact, more than one credible point of view.  I don't think that applies here--after all, would you publish a "balanced" article on perpetual motion machines?  But it also appears at first glance (from my perspective) that you have violated your own criteria--or at least one of them.  How can you verify a topic when the only real evidence supporting it is the claim of the "inventor?"  There's no scientific basis for the assertion that the "CAESAR" concept will work, and a great deal of verifiable evidence that it will not.  Based on what is "verifiable," I can't see any justification for flagging this article as anything other than pseudoscience, until and unless Filippone or someone else can provide "verifiable" scientific data to support his claims.  I've been following "CAESAR" for about 2 years now, and I'd be happy to elaborate on what I've found, if anyone's interested.  In the meantime, I'll refrain from discussing other philosophical issues associated with publication of "voodoo science," but I will observe that if Wikipedia envisions itself as a credible information resource, you are going to have to make some value judgments along the way about what that word "verifiable" really means; I would offer that when you're dealing with science, "verifiable" does not necessarily mean the same thing as it does in other contexts.Anuke 04:25, 23 March 2006 (UTC)


 * As was pointed out by other editors above, this story has developed enough notoriety to warrant inclusion here. I myself was willing to put the article up for a deletion review and was dissuaded by the other editors. Verifiable in the Wikipedia context WP:V is that which can be demonstrated to have been reported elsewhere in other publications, in this case the Economist, it does not mean that the subjects contentions have been proven true. This is a mater of policy here. We both know that you have been disputing rather acrimoniously elsewhere with Filippone, and that is between you and him. If you try and bring this high POV fight here you will likely wind up barred. Edit this topic if you will, but stay within the boundaries of WP:NPOV or your work will be reverted away. --DV8 2XL 05:32, 23 March 2006 (UTC)


 * You misunderstand me; I have little interest in editing the article as it appears in Wikipedia, though I do assert you ought to remove the line about Filippone's affiliation, because the "center" that he directed no longer exists and he is no longer (as far as I can tell) on the faculty or staff of U of M at College Park. (This can be verified on the UMCP website; the fact that the CAESAR web page still exists only attests to the fact that it's very difficult to eliminate things from the Internet once they appear--they may be forgotten, but unless the file is deleted at the source, it sticks around.)  But I also agree with an earlier commenter--to the effect that she holds articles on physics to a "higher standard," and I would extend that comment to science in general.  Wikipedia can set any rules that it wants, I suppose, but in my opinion, your definition of "verifiable" for science-based articles needs some work.  Simply because a story has been reported elsewhere does not make it true (yeah, I know, you don't do "truth"), and most of us who work in science or related fields (such as engineering) know all too well that when science makes its way into the mass media, there's a high probability that some of the information is inaccurate.  In this case, the reporting that has been done is based solely on the word of the "inventor"--whatever his faults as a scientist, he's a fabulous self-promoter.  There has been no information published anywhere else that supports his claims, and as amply discussed above, in my own and other comments, the concept as described in The Economist is nonsense, and it's too bad that no one at The Economist had the perspicacity to realize it (or had the initiative to consult a nuclear reactor engineer for a "second opinion").  Note:  I already contacted the people at the U. of Md. who publish Research Frontiers and told them they ought to be ashamed for publishing such tripe.  If you're going to publish an article on junk science, fine; just be honest enough to call it junk science, and not a design for a nuclear reactor--because people who are not knowledgeable about the issue may not be able to distinguish the difference.  And if you "bar" people who bring such issues to the fore, you are doing far more disservice to the Internet community at large than service.  All I can hope is that people who come to this article take the time to look at this discussion page to find out the real story, and don't take the article at face value (which ain't worth much).Anuke 19:59, 23 March 2006 (UTC)
 * Please take up your argument with the rules with the Foundation or directly with Jimbo Wales. I have nothing to do with the policies here, and if I did they would probable run closer to your ideas than not. I just don't want a war breaking out here and was hoping to nip it in the bud, that is all. --DV8 2XL 20:10, 23 March 2006 (UTC)

Labeling this article pseudophysics is just a polite way of saying that it is BS, and I agree that this reactor is nothing but BS. If Anuke has any links to criticisms of this concept, please add them to this article. pstudier 23:24, 23 March 2006 (UTC)


 * The only recent critique on the Web of which I'm aware is the one that I posted on a blog site of "People Building Peace." PBP published an article on "CAESAR"last September in their on-line newsletter, similar to the one in The Economist, and I contacted the editor, who suggested I post my remarks. Filippone then responded and I addressed his comments in a second post.  As far as I know, that's it.  I've found other discussions on various chat and blog sites, most of which were posted shortly after the article in The Economist, about 3 years ago--and few by anyone who really knows anything about nuclear reactor technology. (Most of them seemed to take the claims at face value and went on to speculate what a great advance it would be if spent fuel could really be used in this manner.  A few raised questions; fewer still were critical.)  This discussion page is the only one I've seen that has recent commentary on the issue and that has information (aside from my own comments) that seriously challenges Filippone's claims.  Anyone who's interested in seeing the older comments can find most of them, I think, by searching on Google using something along the lines of .  I can provide the URL to the PBP blog site if you'd like; as indicated in my original comments, I'm a novice at this and am not sure how to link the site to this page.Anuke 16:57, 24 March 2006 (UTC)

"Disputed science" infobox
If it appears that Dr. Filippone's reactor proposal isn't published academically anywhere or supported by a reputable organization, it's probably safe to stick a "disputed science" box on it, describing how it departs from mainstream understanding of scientific fact. Details of use are here. --Christopher Thomas 07:00, 25 March 2006 (UTC)
 * Yes, for sure. --DV8 2XL 09:31, 25 March 2006 (UTC)
 * One of you should go ahead, then, as you have a better grasp of the background material than I do. --Christopher Thomas 14:10, 26 March 2006 (UTC)

Additional edits
Well, I finally gave in and edited the page, but I kept my own POV out of it; just cleaned up a couple of English gaffes and provided a clearer explanation of the fission and moderation process. For instance, fission itself does not create the "Maxwellian" distribution of thermalized (low-energy) neutrons; rather, that occurs because of the way in which water moderates (reduces) neutron energies. Also, it needed to be made clear that the discussion of delayed neutrons in the articles about CAESAR (e.g., in The Economist), as repeated in this article, represent Filippone's theory. In reality, his claims are nonsense. Aside from the fact that delayed neutrons are "born" at energies below the 1 MeV U-238 fission threshold and thus could not fission U-238 even if they were not moderated by anything, his claims that moderation slows them down so much that they don't contribute to the fission process is utterly absurd. In fact, it is ONLY because of delayed neutrons that nuclear reactors can be controlled. The time between the fission event that creates the fission product that emits a delayed neutron and the emission of the neutron itself varies from seconds to tens of seconds, depending on the actual fission product; this is in contrast to the "prompt" neutrons, which appear in about a millionth of a second (give or take). In a system that is exactly critical (number of neutrons created by fission equals the number lost through absorption or escape), that delayed neutron "delay time" actually controls the rate at which the neutron population grows or declines. And of course, these delayed neutrons, once thermalized (moderated to an energy equivalent to the temperature around them, on the average about 0.025 eV--that's correct, "electron volts," not "million electron volts"), are just as liable to cause fission as any other neutron; the fissile nucleus that absorbs it has no way of "knowing" whether it was delayed or prompt. Note that the fraction of fission neutrons that are delayed is referred to as "beta." For U-235 fission, that number is about 0.0065 (0.65%). Small changes in the "reactivity" of a reactor (a measure of how close it is to exact criticality), within a range plus or minus "beta" cause slow changes in the neutron population (and power). An explanation of this process can be found in almost any text on nuclear energy or nuclear reactors.

In addition, the issue with U-238 is not that it won't fission, but that it can't sustain a controlled chain reaction. If you hit it with high-energy neutrons, it might fission (fission is a probabilistic or statistical process, not a deterministic one), but successive generations of neutrons will not equal the original number and the process dies off very rapidly. Also, Pu-239 is referred to as "fissile," meaning it readily undergoes fission. "Fissionable" means that there is some probability, possibly very low, that it will fission, so U-238 is "fissionable" for neutron energies > than about 1 MeV. I trust these edits are acceptable.Anuke 00:24, 30 March 2006 (UTC)

Additional note: There is a subtle, but crowning, irony in this whole discussion of Filippone's theory. If, in fact, he were correct, a lot of people in the U.S. would be in great danger right this moment. It is possible to make a reactor critical on prompt neutrons alone--logically enough, this condition is referred to as "prompt critical." At that point, though, any further growth in the neutron population would be controlled by the emission time of the prompt neutrons as they fission--there would be no need to "wait" until the delayed neutrons were emitted to balance the neutron equation, so the power would increase by thousands of times (or more) each second. This is how an atomic bomb works. Recall from above that the delayed neutrons given off from U-238 fission do not have enough energy to cause U-238 to fission, so if it WERE possible to make a reactor from U-238, it would have to be critical on prompt neutrons only. (This would also imply, incidentally, that you could make a bomb from U-238.) Now, when uranium is enriched for use in nuclear reactors, the small amount of U-235 in natural uranium (about 0.7%) is concentrated in a U-238 matrix. Since mass must be conserved, there is a large amount of U-238 that has been depleted in U-235 (called, logically enough, depleted uranium) in the "tails" that come from the enrichment process. The concentration of U-235 in that material is not zero, but it's down to about 0.2-0.25%; i.e., it's almost pure U-238. This material is often stored in drums at the enrichment plant. If it were possible to make this material into a reactor, as Filippone claims, each drum of depleted uranium would be a potential bomb!! Of course, this is nonsense; that depleted uranium is in no danger of becoming an atomic bomb because U-238 can't sustain a chain reaction. Think about it. And if this argument does not convince you, get copies of the articles from The Economist and the U. of Md. "Research Frontiers" from the links above (since there are no other publications to which you might refer), go on the Internet and look up the name of a nuclear engineering professor--there are about 30 or so NE departments around the U.S.--and send him/her the papers with a letter asking him/her to provide an opinion as to whether the concept as described in those papers is physically possible. Let me know if you get an answer.Anuke 02:22, 30 March 2006 (UTC)

Comment moved from article
(Originally posted to main article by User:151.200.150.228 (talk • contribs) on 15:54, 4 May 2006.)

I simply wanted to add a technical clarification. The CAESAR concepts is NOT only based on steam moderation. The CAESAR core is equipped with special thermal-hydraulic systems able to "switch" coolant density from super-heated steam (extremely low densities) to pressurized liquid water (higher density). Under these conditions the core can, via external operations, be operated as a gas-cooled system (where the gas is H2O-gas) and, controllably, create fissile materials. Later, when the inventory of fissile materials has reached a desired level the core is switched back to thermal-neutron operation, thereby burning the fissile materials it had previously created. Therefore, CAESAR can sustain chain reactions based on its own unique "enriching" capabilities. All statements indicating that the CAESAR core is able to operate only by splitting U-238 are incomplete and feed an army of skeptics too eager to shut down new ideas. CAESAR can sustain chain reactions because it is a machine that "transforms" its core characteristics from gas-to-liquid moderators on command and quickly (the 2 meter long laboratory analog at the University of Maryland is switched from liquid water to steam operation in approximately 7 milliseconds). This is the key that allows this core to operate as a breeder that can become a thermal reactor whenever it is desired or needed.

Claudio Filippone
 * This was moved here as this kind of entry is not permitted in the main namespace. --DV8 2XL 16:24, 4 May 2006 (UTC)

A challenge to Filippone
Ah, so now CAESAR is a "breeder" reactor. A breeder reactor requires a driver core to produce neutrons that can be absorbed in the fertile material to create more fissile material. This "clarification" does nothing to explain how the "driver" operates--though there is at least an implication that it is still based on U-238 fission. This is typical of how the "inventor" of this "reactor" has responded to criticism; he claims that the design has been misrepresented in various articles/descriptions/discussions. Of course, since he has never published a technical paper or journal article detailing the design, he can claim anything he wants; there is no objective evidence that can be used to refute such claims.

It is still impossible to create a reactor with U-238 as the fuel. It is still impossible to "tune" the energy of delayed neutrons so that they will fission U-238, since they are "born" with energies below the 1 MeV U-238 fission threshold energy. As far as designing a reactor that can change coolant characteristics at the touch of a button, Filippone's claim overlooks the fact that the optimum configuration (e.g., fuel pin size, spacing, enrichment) of a system operating on thermal neutrons is different from that of a system operating (in a steam-cooled environment) on a harder (more energetic) neutron spectrum.1 Not to mention the sorts of materials-related issues that would arise in changing rapidly from a high-pressure, high-temperature liquid to a superheated steam environment (or vice-versa), if such a transformation was, in fact, possible. (The claim that a 2-meter-long "laboratory analog" can supposedly achieve such a transformation in the blink of an eye proves nothing about how a real reactor core--with real thermal-hydraulic/neutronic feedback--would behave.)

In any event, a breeder reactor is not a new concept; it's only been around for about 50 years. A gas- or steam-cooled breeder is not a new idea either; that's been around for at least 30 years. And long-life (30+ year) cores that essentially both breed and burn have been studied for at least 25 years. So the only thing that is "new" about CAESAR is the part that doesn't work (fissioning U-238).

But here's my challenge to Filippone: submit a paper on CAESAR, with a full description of the design and its operation (including, preferably, thermal-hydraulic and neutronic analyses), to a reputable nuclear engineering technical journal, either the American Nuclear Society's "Nuclear Technology" or Elsevier's "Nuclear Engineering and Design." (A description of your "laboratory analogs" along with scaling analyses showing that the results are valid for the reactor design would be helpful, too.) Let the technical community peer-review your work. As long as you refuse to take that step, it is impossible to treat your claims as anything more than pseudo-scientific nonsense.

I'll give Filippone one thing, though. He claims his "reactor" is "environmentally safe." Well, the safest reactor is one that can't operate--if it doesn't operate, it poses no risk. So I guess that claim must be true.Anuke 17:47, 4 May 2006 (UTC)


 * 1Much different, in fact--pointing out yet another problem with the design as described. Fissile enrichments in thermal (slow neutron) systems range from about 2-5%, depending on plant design and fuel management schemes.  Fissile enrichments in breeders (fast [unmoderated] neutron spectrum) are on the order of 20%, because fission cross sections (interaction probabilities) for fissile materials generally decrease with neutron energy.  (Recall that U-238 is not fissile, so this characteristic does not apply.)  Thus, even if CAESAR could operate as described (which it cannot), switching from gas (steam)-cooled to liquid water-cooled operation would mean operating a thermal reactor at enrichments on the order of 20% fissile.  Not only would this violate Nuclear Regulatory Commission rules (which limit thermal power reactor fissile enrichment to a maximum of 5%), but it would likely create an unsafe system because it would degrade the normal reactivity feedback mechanisms that allow thermal reactors to be operated safely.

A General Warning
The two previous posters have a long history of debate elsewhere in cyberspace, and I want to make it very clear to both of them that we maintain a high standard for courtesy here and I will have no problem reporting any violations to the Admins. In particular I would like to draw their attention to our standard of "assume good faith." --DV8 2XL 18:32, 4 May 2006 (UTC)
 * I don't have a problem with this. If you define "good faith" as believing what you say, I'll accept that Filippone believes what he has written about his "invention."  However, that "invention"--and his claims (as reported in "The Economist," "Research Frontiers," and his own comments on this page)--violate just about every law of nuclear reactor physics of which I'm aware and/or contravene scientific evidence developed over 60+ years of nuclear reactor design and operation, and he has not presented one shred of objective, verifiable evidence to support his claims.  I'm sure the folks who "invented" cold fusion believe in what they did, too--but that doesn't make it true.  "Belief" is a subjective matter; however, real science deals in objective facts.  That may not be part of Wikipedia's standards, but facts do matter.Anuke 20:32, 5 May 2006 (UTC)
 * I was referring only to comportment in discussion. See WP:NPA As for truth, the policy here is verifiability not truth. See WP:V. While I happen to agree that Filippone's claims do not make much sense, the fact that his ideas have had wide dissemination makes them notable enough for inclusion here. --DV8 2XL 20:59, 5 May 2006 (UTC)
 * ...With the caveat that this doesn't mean the claims should be presented as _fact_ here. However, the last version of the article I looked at seemed to make the differences in views between Dr. Filippone and the majority of scientists sufficiently clear. --Christopher Thomas 06:21, 6 May 2006 (UTC)

Having been in two seminars by Filippone...
... I can attest that there was a lot of interest in the idea, even from several well-funded nuclear physicists. I am surprised at the venom, given the level of information of some posters. Here is a summary of what I know about CAESAR:

1) the primary cooling is done with heat cavities (a steam film) which should produce negligible moderation. Because of the high steam temperature, fuel cladding can not be manufactured out of zirconium alloys (which is attacked by steam). It would have to be one of the silicon and carbon based materials that the NGNP project was supposed to develop (I believe funding for NGNP, projected to be $1.4B with about 1 billion devoted to the development of new materials, has now been eliminated). Filippone said that in fact the whole core (structural elements as well) should be made of such materials. There were objections re: the use of heat cavities in one of the seminars, related to steam exceeding the speed of sound (and therefore creating a destructive shockwave) and also how to handle the recoil force of the ejected steam. No one saw a showstopper there.

2) As pointed out above, there are parts of the core which can be filled with water for the purpose of switching from thermal to breeder operations. Because the reactor has to operate in thermal mode, one has the material constraints of a thermal reactor (materials with low capture cross section). Because it is to be operated at high temperatures, it has to be new materials.

The crucial point, however, and everyone agreed, is that there is no neutronics calculation confirming or dispelling the possibility of having a working point in the nuclear reactor parameters. Dr Filippone, being a hardware man by training, would not be able to do the calculation himself in a reasonable amount of time. Even though I am fluent in one of the standard nuclear codes, for which I was a beta tester in the early 1990, and have programmed for two decades, it would take me six months to evaluate the neutronics. It is not something that can be done without funding.

So it is a problem of chicken and egg. No funding no neutronics. No neutronics no funding. In my opinion, if a working point exists, it would be for a large core (with large power), and the aforementioned as yet undeveloped carbon structure. It is very possible that the uranium would have to have some level of enrichment.

But, the merit of the idea is that perhaps there is a way to use a reactor in dual mode. I am pretty sure no one else said it before. The device would burn more uranium than current devices, and would significantly diminish proliferation problems.

In regard to some of the comments posted here,

1) I don't know that this project needs a "pseudophysics" tag. It is unproven but not necessarily wrong. It is unfeasible with current standard nuclear technology, but the possibility exists with materials which the community wanted to develop only last year. The projected advantages of this idea have a lot of merit 2) The NRC does not rule over what is physically true. It rules over what is perceived as safe given current technology. 3) breeders work at 20% enrichment because they have very small cores. The CAESAR concept leads to cores which are larger, and therefore require less enrichment.

Gbli 03:10, 25 January 2007 (UTC)

Response to comments above
1. As originally described by Filippone (a U-238-fueled reactor that operates by means of "tuning" delayed neutron energies--see the 2003 article in "The Economist"), the "psuedophysics" tag is appropriate, since it is physically impossible to design a reactor that operates in such a fashion. As far as I'm aware, Filippone has still (as of May 2007) not published anything that could be peer-reviewed that describes in full what his design actually comprises or how it works. More recently, every time Filippone presents something on his "concept," it has morphed into something else: a breeder, a breeder/burner, etc., etc. In my view, his funding problem, if that's what it is, could be solved relatively easily: submit an article to a peer-reviewed publication (see "A challenge to Filippone," above). If the technical community thinks this is an idea worth pursuing, people will be willing to work on it. The basic neutronics could probably be investigated as a Master's thesis, on the cheap. But I'm betting that the technical community will see this as bogus, as extensively documented above. (I cannot document it, but I understand from one source that someone at MIT asked for information from Filippone about the design so that it could be studied further, and Filippone either would not or could not provide what was requested.)

2. I'm not sure what the point of the comment about the NRC was supposed to be. What I said was accurate--that the enrichment needed (see next comment) is far in excess of what the NRC permits for thermal reactors.

3. The statement regarding core size is incorrect. Breeders--at least, fast (low-moderation) breeders--require (relatively) high enrichments because fission cross sections decrease substantially at increased neutron energies. It's not primarily a function of core size. (See "Fast Breeder Reactors," by Waltar and Reynolds, p. 46.) Even for a 3000+ MW (thermal) fast breeder core, comparable to the output of today's large water-cooled reactors, the average enrichment (or fissile fraction, in a Pu-fueled core)is in the range of 15-20%. (Core size is, on the other hand a factor in thermal reactors--in general, the larger the core, the lower the neutron leakage, and the lower the necessary enrichment.) Operating a reactor in a "dual-mode" configuration (water-cooled thermal burner/steam-cooled fast breeder) thus becomes a significant nuclear design challenge. The enrichment you need for a fast spectrum is generally too high for a thermal reactor, unless it's very small or operating very inefficiently. (And incidentally, if you think that steam moderation of neutrons is "negligible," see p. 132 of Waltar and Reynolds, which shows the energy spectrum for various breeder reactor designs. Steam causes a significant shift to lower energies.)

Incidentally, I suspect that the discussion of the problems with zirconium-based cladding in a steam environment would come as a surprise to boiling water reactor designers, who use zirc-based cladding in their steam-and-water-cooled cores. Of course, there are no details provided (anywhere) as to the temperatures and pressures involved in the CAESAR design, so it is impossible to determine if the conditions under which the reactor is proposed to operate are, in fact, in the range in which steam becomes excessively corrosive to zirc. In any event, it is worth noting that studies are currently being carried out for reactors cooled by water at supercritical conditions (temperatures up to around 500 degrees C), and while zirconium-based cladding is not appropriate (because of corrosion), other metallic cladding materials, e.g., ferritic-martensitic stainless steels or dispersion-strengthened "super alloys," may be. Thus the potential lack of funding for development of silicon carbide-based materials for NGNP, even if true, is largely irrelevant. As discussed above, the concept of a steam-cooled breeder reactor has been around for a long time; if that's all the CAESAR concept comes down to, it's hardly new, novel, or innovative. As far as "dual mode" operation is concerned, it might be _possible_ to design a reactor that operates as both a water-cooled burner and a steam-cooled breeder (though I strongly suspect it would not look like "CAESAR"), but in view of the challenges involved with materials, nuclear design, and operations, not to mention safety, I have to ask "why bother?" I do not believe the claim ("projected advantages") that the U/Pu utilization of such a design would be superior to other, far simpler (and technically demonstrable) concepts. Despite the fact that Filippone has been working on this "concept" for something like 10 years, including his doctoral research at U. of Maryland, he has absolutely nothing to document its supposed superiority, except some flashy slides and--I gather--a persuasive spiel. He's apparently a great salesman...but I reserve judgment on his capabilities as a nuclear engineer until I see some real proof.User:Anuke 17:55, 3 May 2007 (UTC)Anuke