In-Reply-To: <[EMAIL PROTECTED]> Organization: http://www.cosmicpenguin.com/911
On Wed, Mar 02, 2005 at 10:41:47AM -0800, Jones Beene wrote: >The reaction p+11B --> 3 alphas has always seemed the ideal, >in-a-perfect-world kind of nuclear reaction for ecological >energy production. Would this reaction p + 11B -> 3 alphas + 8.7 Mev be a candidate for hydrino fusion (resulting in fission), in an electrolytic or plasma-electrolytic cell? 80% of boron atoms are 11B, the rest are 10B. Boric acid (H3BO3) and borax (Na2B4O7) are highly soluble in hot water. Boric acid, H3BO3 -- solubility 27.6% at 100degC Borax (Disodium Tetraborate) pentahydrate, Na2B4O7 x 5 H20, water solubility: 160 g/l (60degC) Is the required proton energy for hot fusion of p+11B higher than for d+t or d+d? If so, does that mean that the proton has to get closer to the B nucleus to fuse, thus requiring an even tinier hydrino than for deuterino+deuterino fusion? __________________________________________________________ Here's an analysis of neutron production in p + 11B hot fusion from secondary reactions (fixed -- it was written in all lower case, with no paragraph breaks). Maybe in water the alphas would be slowed down before they could react with boron and create a neutron? > http://www.gerhard.de/gerold/owa/gerhard.browsen_soif?form_seq=979306&form_timestamp=&form_language=0 > http://www.gerhard.de/gerold/owa/gerhard.browsen_soif?form_seq=979306 > > Radiation from "Aneutronic" Fusion > Arthur Carlson > > Written: 1998 Jul 9, replacing the version first written 1998 Feb. > > Status: I'm starting to understand the issues, but the answers > are by no means final. > > Disclaimer: the content of these pages is my responsibility and > does not necessarily represent the position of my employer. > > Fusion based on exotic reactions like proton-boron11 is sometimes > claimed to use and produce no radioactive substances, thus freeing > fusion from the burden of radiation damage, biological shielding, > remote handling, and safety issues. We will here investigate > under what conditions and to what extent that is true, without > regard to the perhaps insurmountable difficulties of producing > net energy from the process. > > An "aneutronic" reaction is often defined as one where no more than > 1% of the total fusion energy released is carried by neutrons. > Detailed calculations [Heindler and Kernbichler, Proc. 5th > Intl. Conf. on emerging nuclear energy systems, 1989, pp. 177-82] > show that at least 0.1% of the reactions in a thermal p-B11 plasma > would produce neutrons. This is still an awful lot of neutrons, > as can be seen by the following simple calculation. > > If we assume 0.1% of the energy is carried off by neutrons, even a > "kitchen-sized" reactor with 30 KW of fusion power will produce 30 > w of neutrons. If there is no significant shielding, a worker in > the next room, 10 m away, might intercept (0.5 m^2)/(4 pi (10 m)^2) > = 4e-4 of this power, i.e., 0.012 W. With 70 kg body mass and the > definition 1 erg/.01 j/kg, we find a dose rate of 0.017 rad/sec. > Using a quality factor of 20 for fast neutrons, this is equivalent > to 0.34 rem/sec. The maximum yearly occupational dose of 5 rem > will be reached in 15 sec, the fatal (LD-50) dose of 500 rem will > be reached in half an hour. > > For an industrial size (100 MW) reactor under the same assumptions, > the dose rate would be thousands of time higher, and anyone > standing nearby would be dead in a fraction of a second. > The neutrons would also activate the structure so that remote > maintenance and radioactive waste disposal would be necessary. > Of course, material damage and safety problems would be brought > into an easily manageable range. > > If we look at where these neutrons come from, they are dominated by > the reaction 11B + alpha -> 14N + n + 157 kev. If we really want > to eliminate neutrons, we see that we cannot tolerate fast alphas > in the plasma. Usually, the product alphas are relied on to keep > the fuel hot. If the alphas have to be extracted with their full > energy, we will need very, very efficient processes to collect > this power, transfer it, and drive whatever process maintains > the plasma energy. The reaction itself produces only 157 kev, > but the neutron will carry a large fraction of the alpha energy, > which will be close to e_fusion/.9 mev. This should be large > enough that the gammas produce some nuclear reactions, including > (gamma,n) reactions, in the structure. > > Suppose we can do this, so that fast alpha reactions are suppressed > by several orders of magnitude. We will always have the fuel ions, > protons and borons. Of course, p+p doesn't do much, and boron-boron > reactions can probably also be neglected due to the large coulomb > barrier. The species can however react with one another in a number > of ways to produce neutrons. These reactions are all endothermic. > > The smallest barrier is for the reaction 11B + p -> 11C + n - > 2.8 mev in a thermal plasma of a few hundred kev temperature, > there is a sufficient number of protons in the high energy tail > that this reaction is a significant source of neutrons. If the > proton temperature is reduced below about 30 kev, then this process > is suppressed, but there is also no longer any significant fusion. > > The only way around this dilemma is to produce a nearly > mono-energetic proton energy distribution, that is, a beam. > If the beam energy is chosen to be at the fusion resonance around > 600 kev, then the reactivity is also about three times higher than > the maximum for a thermal plasma. > > Let us assume that we can produce and maintain such a non-maxwellian > distribution, so that (p,n) reactions are suppressed by several > orders of magnitude. What is the next most serious source > of neutrons? Probably those associated with fuel impurities. > If the density of fast alphas and fast protons is controlled to > suppress reactions with 11B, then the reactions with impurity 10B > should be similarly suppressed for the same reasons. > > The impurity deuterium density must be kept low enough to suppress > d-d fusion. Since the fusion rate is proportional to the square of > the deuterium density, I presume that this is not too difficult. > More serious is perhaps the reaction 11B + d -> 12C + n + 13.7 > mev the cross section for this reaction should be similar to that > for p-11B fusion, so that it will be necessary to use very pure > hydrogen fuel. I haven't analyzed this problem, but considering > the factor 2 mass difference and the small amount of fuel needed, > i assume that it is technically and economically feasible to reduce > the deuterium concentration several orders of magnitude below its > natural abundance of 1.5e-4. > > Let us assume that fuel of sufficient chemical and isotopic purity > can be made. Any other elements getting into the plasma, for > example through outgassing of the walls, are another potential > source of neutrons. Any energetic fuel or product particles > striking solid surfaces can also produce neutrons. It is difficult > to estimate the severity of these reactions, even with a particular > configuration in mind. If, in addition to the other assumptions > above, we assume that interactions between the plasma and the > containment device can be adequately controlled, then neutron > production will be suppressed by many orders of magnitude. > > What other types of radiation will be a concern? Bremsstrahlung > will produce extremely large quantities of hard x-rays, which must, > and I suppose can, be shielded by a modest amount of metal. > > The fusion reaction 11B + p -> 12C + gamma + 16.0 mev will produce > 4, 12, and 16 mev gammas with a branching probability relative to > the primary fusion reaction of about 10^-4. With no shielding, > this would be a tremendous radiation dose. The calculation above > would apply if the production rate is decreased a factor of ten > and the quality factor is reduced from 20 to 1. Without shielding, > the occupational dose from a small (30 KW) reactor would still be > reached in about an hour, so enough shielding must be installed > to attenuate the hard gamma flux by well over three orders of > magnitude. For an industrial reactor, the attenuation should be > well over six orders of magnitude. > > This should be doable, but does not, in my opinion, support the > statement of Rostoker, et al., in Science, that "radioactivity > from side reactions is negligible". >
