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USOO8625731B2

(12) United States Patent (10) Patent No.: US 8,625,731 B2 Holden et al. (45) Date of Patent: Jan. 7, 2014

(54) COMPACT NEUTRONGENERATOR FOR (51) Int. Cl. MEDICAL AND COMMERCIAL SOTOPE G2G 4/02 (2006.01) PRODUCTION, FISSION PRODUCT G2G 4/00 (2006.01) PURIFICATION AND CONTROLLED (52) U.S. Cl. GAMMA REACTIONS FOR DIRECT USPC ...... 376/108: 376/112:376/156 ELECTRIC POWER GENERATION (58) Field of Classification Search USPC ...... 376/157, 108,156, 171, 172 (76) Inventors: Charles S. Holden, San Francisco, CA See application file for complete search history. (US); Robert E. Schenter, Portland, OR (US) (56) References Cited *) Notice: Subject to anyy disclaimer, the term of this U.S. PATENT DOCUMENTS patent is extended or adjusted under 35 3,748,226 A * 7/1973 Ribe et al...... 376,124 U.S.C. 154(b) by 961 days. 3,778,627 A * 12/1973 Carpenter ...... 376, 192 4,749,540 A * 6/1988 Bogartet al...... 376/133 (21) Appl. No.: 12/296,844 4,997,619 A * 3/1991 Pettus ...... 376,288 2004/02284.33 A1* 1 1/2004 Magill et al. ... 376/347 (22) PCT Filed: Apr. 13, 2007 2005/022O248 A1* 10, 2005 Ritter ...... 376/190 2008/O144762 A1* 6/2008 Holden et al...... 376/416 (86). PCT No.: PCT/US2OOTAO66668 * cited by examiner S371 (c)(1), (2), (4) Date: Oct. 10, 2008 Primary Examiner — Jack W Keith Assistant Examiner — Sean P Burke (87) PCT Pub. No.: WO2008/060663 (74) Attorney, Agent, or Firm — Craig M. Stainbrook; PCT Pub. Date: May 22, 2008 Stainbrook & Stainbrook, LLP (65) Prior Publication Data (57) ABSTRACT A neutron generator and production apparatus and US 2011 FO268237 A1 Nov. 3, 2011 method ofusing the same to produce commercially and medi cally useful neutrons. The gamma,n reaction produces neu Related U.S. Application Data trons in and deuterium and the spectrum of the (60) Provisional application No. 60/792,065, filed on Apr. neutrons generated is shaped to optimize capture of the neu 14, 2006, provisional application No. 60/792,066, trons in a gamma emitting isotope. The gammas interact with filed on Apr. 14, 2006, provisional application No. target materials to produce large quantities of neutrons. 60/792,067, filed on Apr. 14, 2006, provisional application No. 60/805,541, filed on Jun. 22, 2006. 14 Claims, 3 Drawing Sheets

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US 8,625,731 B2 1. 2 COMPACT NEUTRON GENERATOR FOR , and other high gamma emitting materials MEDICAL AND COMMERCIAL SOTOPE after one or Successive neutron captures or from gamman PRODUCTION, FISSION PRODUCT reactions on high-Z materials such as , , PURIFICATION AND CONTROLLED and . GAMMA REACTIONS FOR DIRECT For the purpose of this application the thermal ELECTRIC POWER GENERATION region is defined as /1000 electron volts to 5/10 electron volts, the epithermal energy region as 5/10 electron volts to 5000 BACKGROUND OF THE INVENTION electron Volts, the fast energy region as five thousand electron volts (five kilo electron volts, 5 keV) to one million electron 1. Technical Field 10 Volts (1 MeV) and the high energy region as above one mil The present invention relates generally to a novel method for producing neutrons in a controlled manner in a novel type lion electron volts (1 MeV) and in some cases in excess often of neutron generator, and more particularly to a novel method million electron volts (10 MeV). and apparatus for producing commercially and medically The novel neutron generator of the present invention uses useful by transmuting selected precursor isotopes 15 gamma photons to dissociate nuclei of beryllium and/or deu using gamma radiation. terium or to produce neutrons from bismuth, lead, thorium or 2. Background Art uranium. The apparatus is best Summarily described as a It is well known that neutrons produce valuable isotopes photo nuclear neutron generator and isotope producer. Using used in Scientific research, manufacturing, and medicine. the inventive apparatus, gamma photons are produced in vari Radioactive isotopes are employed in Scientific research in ous alloys or compounds of gamma emitting isotopes. Exem fields as diverse as hydrology and life Sciences. Isotopes are plary gamma emitting isotopes that function by neutron cap used in business and commerce in many manufacturing pro ture include, but are not limited to: Vanadium-50, Vanadium cess and in the production of oil and gas. The most valuable, 51, -59, nickel-61, iron-57, iron-54, -167, yet some of the most difficult to make isotopes, are used in the -151 europium-153, -155, gadolinium diagnosis and treatment of human diseases and disorders. 25 157, -79, -105, palladium-107, and others It is also well known that fission in nuclear reactors pro being high-Z refractory materials such as , , duces fission products that area component of nuclear waste. and functioning as a “converter in which Isotopes are currently produced by electron beams, ion energetic electrons are slowed down and emit penetrating and beams, in and in nuclear reactors. Some isotopes energy gamma photons. may be produced by any of the four general methods. Others 30 The inventive photo nuclear neutron generator is a very by one method alone. The science of isotope production compact "plug-in neutron generator that obviates the need involves adding or subtracting the requisite number of nucle for large reactors to produce neutrons for several applications ons (protons or neutrons) to or from the target's parentisotope and uses including: (1) production of therapeutic medical to produce the desired end product in significant quantities isotopes and other important isotopes used for the treatment with appropriate purity. 35 or diagnosis of disease or for the production of other com The transmutation reactions that change the number of mercially significant isotopes, (2) production of penetrating protons or neutrons in the isotopes include photo nuclear gamma radiation for industrial applications; (3) production of reactions wherein energetic gamma photons eject neutrons neutrons for the waste treatment of fission products from from nuclei. Also high energy neutrons are able to displace or spent light water reactor fuel to convert the fission products to eject protons from nuclei. Transmutation reactions caused by 40 shorter lived or stable isotopes; (4)) for motive power appli accelerated ions such as protons, deuterons, nuclei cations and (5) the gamma photons can also transmute matter and other ions collide with the nuclei of the target material to by ejecting neutrons from nuclei to accomplish transmuta change the isotope from one to another. These reactions gen tions with the same results and purpose as the aforesaid four erally do not yield the quantity of desired product material as applications and uses. efficiently as reactions involving Successive or singular neu 45 There has thus been broadly outlined the more important tron capture in the nuclear reactor. The above mentioned features of the invention in order that the detailed description reactions also are not as efficient in the treatment of fission that follows may be better understood, and in order that the products to transmuted them to shorter lived isotopes or com present contribution to the art may be better appreciated. mon stable isotopes. Additional objects, advantages and novel features of the 50 invention will be set forth in part in the description as follows, DISCLOSURE OF INVENTION and in part will become apparent to those skilled in the art upon examination of the following. The present invention relates to an inventive compact neu Furthermore, Such objects, advantages and features may be tron generator and isotope production apparatus and method learned by practice of the invention, or may be realized and of using the apparatus to produce copious amounts of com 55 attained by means of the instrumentalities and combinations mercially and medically useful neutrons. The gamma,n reac particularly pointed out in the appended claims. tion produces the neutrons in beryllium and deuterium as well Still other objects and advantages of the present invention as high-Z materials such as bismuth, lead, thorium and ura will become readily apparent to those skilled in this art from nium. The produced neutrons from gamma in reactions are the following detailed description, which shows and moderated or their spectrum is shaped so that the capture of 60 describes only the preferred embodiments of the invention, neutrons in the target isotope is maximized. simply by way of illustration of the best mode now contem The present invention advances the art by employing alloys plated of carrying out the invention. As will be realized, the fashioned from materials that emit energetic gamma radiation invention is capable of modification in various obvious to obviate the use of a reactor or a for these appli respects without departing from the invention. Accordingly, cations when stimulated by high energy electrons. 65 the drawings and description of the preferred embodiments The novel method disclosed herein takes advantage of the are to be regarded as illustrative in nature, and not as restric energetic gamma radiation emitted from , tive. US 8,625,731 B2 3 4 BRIEF DESCRIPTION OF THE DRAWINGS tube, or foil form. This is followed by an outer ring of spec trum shaping alloy 230, and an outer ring of neutron multi This invention will be better understood and objects other plying target material 240 or gamma converting material. An than those set forth above will become apparent when con optional reflector 250 may be axially disposed around the sideration is given to the following detailed description 5 outer ring of neutron multiplying target material in order to thereof. Such description makes reference to the annexed reflect generation neutrons back to the target to drive drawings wherein: fission reactions. The reflector is preferably fabricated from FIG. 1 is a schematic view showing a first preferred beryllium, beryllium deuteride, beryllium triteride, or heavy embodiment (i.e., a two chamber design) of the neutrongen water producing thermalised neutrons. erator/isotope production apparatus of the present invention: 10 Channels 215, 225, 235, 245, may be disposed around and FIG. 2 is a perspective view of the compound target assem between each of the material layers and provided with circu bly (or “capsule') employed in a second preferred embodi lated air or heavy water to cool each layer of the target assem ment of the neutron generator apparatus of the present inven bly. Alternatively, in embodiments where cooling is either not tion; desired or not needed, the channels may be eliminated and FIG. 3 is top cross-sectional perspective view thereof; 15 each material layer (ring or tube) disposed immediately upon FIG. 4 is a cross-sectional end view in elevation of the and approximated to the underlying material layer (ring, tube, target assembly of FIGS. 2 and 3; and or rod). FIG. 5 is a cross-sectional end view in elevation of the FIG. 5 is a cross sectional end view in elevation of the central neutron generator cavity showing structure where the central neutrongenerator cavity where the capsule is attached electronaccelerator tube is attached to an electronics package 20 to an electronics package 270, and showing the relative posi and further showing the gamma generating alloy forming the tion of gamma generating alloy forming the cup 280 and cup and the selected target material for the gamma,n reaction. selected target material 290 for the gamma,n reaction. The gamma emitting assembly of the photo nuclear neu BEST MODE FOR CARRYING OUT THE tron generator of the present invention has unique design INVENTION 25 characteristics. There are common elements to the preferred embodiments of the present invention. The first common Referring to FIGS. 1 through 5, wherein like reference element is the use of neutron multiplication in by elevating the numerals refer to like components in the various views, intensity of cascades of gammas in two or more Volumes wherein FIG. 1 is a schematic view showing a first preferred (200, 240) within the compound target assembly 100 shown embodiment of the neutron generator and isotope production 30 in the diagrams and/or figures. The X-ray Source is depicted as apparatus of the present invention. This view shows that an a tube or rod 200 in the central axis of the cylindrical electron exemplary embodiment 100 includes an electron beam or particle accelerator. source 300 which directs an electron beam, preferably 10 The second element common to all of the preferred mA, between 16 and 32 MeV, to a first chamber, which is a embodiments is the use of a spectrum shaping gamma emit converter cell. The converter cell preferably comprises a hol- 35 ting alloy disposed proximate the neutron multiplying target. low rectangular 2 mm tungsten alloy channel or tube 1 with an These are “cups' 210 of gamma emitting alloy that “hold” or interior Void 2 through which cooling water or other working surround the LBE. These cups are preferably jacketed and fluid Such as helium, dioxide, or selected liquid metal cooled by heavy water pumped through a channel 215 that or alloy of liquid metals as may be continually circulated to also contributes neutrons to the central area of the target. The export heat and enable long term operation of the system. 40 gamma emitting alloy 210 includes spectrum shaping addi While tungsten alloy is the preferred alloy material, alloys of tives that soften the high energy spectrum to an epithermal or other refractory metals, such as rhenium, niobium and or thermal neutron spectrum as needed to promote the most tantalum, or any combination thereof as computationally efficient capture in the selected isotopes comprising the optimized, may be employed. The electron beam source is gamma emitting alloy. separated from the converter cell by dry air 400, which sur- 45 In the preferred embodiments, the metal matrix for shaping rounds the two chambers. the neutron spectrum is composed of vanadium nickel erbium The system next includes a second chamber 4, which con europium or other selected lanthanide(s) that are computa tains one or more target isotopes, and the Volume of target tionally optimized. Aluminum has low parasitic neutron isotope may be demised into a plurality of cells 10-13, 20-23, absorption cross-section, and nickel has high elastic scatter 30-33, 40-43, 50-53, 60-63, 70-73, 80-83, and 90-93, which 50 ing cross-section. Other metals of the alloy such as Vanadium receive various amounts of exposure to gamma rays at various or have unique neutronic properties so these can be . The energy dependent photon fluence may be cal added to improve neutronic behaviors in the spectrum shap culated for each Zone. ing matrix that assists capture in the gamma producing alloy. FIGS. 2-5 show a compound target assembly of a second The atoms in the hydrides function to soften preferred embodiment of the inventive compact neutrongen- 55 neutron spectrum to its optimal shape for transmutations that erator and isotope production apparatus of the present inven produce gamma radiation. The metals that form the intermet tion, showing the target assembly 100, including a central alic deuteride compounds include , europium, gado power rod 200, preferably consisting of high-ZX-ray emitting linium, erbium, , Zirconium, Vanadium, and tita material Such as lead bismuth eutectic, and even more pref nium. Additionally, various oxides are known to shape or erably spiked with or neutron multiplying 60 tailor neutron spectra. These include Zirconia, alumina, and material. This is disposed in an inner tube of spectrum shap lithia-7. Finally carbide compounds and nitrides as homoge ing material, preferably a gamma emittingerbium-167-nickel neously dispersed fine particles can be used with the hydrides cup 210. The cup may be cooled by heavy water pumped to assist in slowing neutrons down in aluminum alloys. All of through channels 215, exterior to the cup, as shown. the additives are fine powders that are homogeneously dis Axially disposed around the inner tube of spectrum shap- 65 persed in the alloy. ing material (and preferably spaced apart therefrom) is a ring The photo nuclear neutron generator can be configured to or tube of precursor isotope target material 220, in either ring, produce more than one medical isotope at a time and can also US 8,625,731 B2 5 6 be used to produce electrical energy. The device can produce aluminum zirconium alloys. This scattering alloy functions as many Positron Emission Tomography (PET) Isotopes, vari a moderator and allows neutrons to be slowed in a controlled ous longer lived positron emitting isotopes, and -225 manner so that they reach the reduced energy needed for and many other useful isotopes by the gamma,n reaction. effective capture in the selected gamma emitting isotope. Further, long lived fission products, mid Z isotopes can be The scattering materials are preferably low Z ceramics transmuted to shorter lived isotopes or to stable isotopes as a tetra carbide (B4C) with the boron as boron-11, method of the treatment of nuclear waste using this type of -7 boride (with the boron as boron-11), lithium-7 neutron generator/neutron ejector. nitride, and boron nitride (with the boron as boron-11). These When the purpose of the inventive neutron generator is to are low-Z materials with low and they can be produce useful amounts of electrical energy for motive appli 10 combined with hydrides of Zirconium, , Vanadium, cations, then the materials interacting with the gammas would lithium to provide spectrum softening effects to optimize the be selected to produce gamma,2n reactions to multiply the spectrum for capture. For increasing the probabilities of the number of neutrons producing gamma photons. These gam gamma,n reaction, the shaping alloy can be nickel aluminum, mas do not have to be highly energetic So that the selected NiAl, with zirconium hydride. The main alloy matrix lanthanides can provide much of the mass of the gamma 15 employed to produce the gammas is Er-Ni, in which the emitting alloy and the lanthanide Such as erbium-167 has a erbium is erbium-167. high affinity for neutrons having thermal energies. This appa Using the inventive method, neutrons can be generated ratus is called the Photo Nuclear Neutron Generator. For this using a high energy electron beam 275 that interacts with a embodiment matter which most easily “ejects’ neutrons (be liquid lead bismuth eutectic (LBE). The LBE is either spiked ryllium, deuterium, bismuth, lead, thorium, uranium, for with particles of fissile uranium-233, uranium-235 and/or example) is illuminated with energetic gamma radiation gen -239 alloyed with optimized amounts of beryllium, erated from neutron captures in electron slowing down reac or it is not spiked with fissile material but is instead alloyed tions or from neutron capture in vanadium 50 and 51 nickel 61 with beryllium. Spiking with fissile material will increase or similar isotopes with the selected lanthanides disclosed in neutron production provided there is Sufficient spectrum paragraph one above. These isotopes have the attribute of 25 shaping material present. to moderate the produced neutrons emitting energetic gamma photons above the five million to thermal energies with the highest cross-sections for n, electron volt level. These gammas interact with neutron shed fission reactions. The incident electrons produce energetic ding matter to cause a gamma,2n reaction in beryllium and in X-rays in the gamma ranges of the electromagnetic spectrum deuterium or in lead. For the effect to take place in beryllium from interactions with the high-Z materials comprising the the incident photon must have energy in excess of 1.67 MeV. 30 LBE, lead bismuth eutectic that may also contain thorium, For deuterium the energy must be in excess of 2.24 MeV. The uranium and one or more selected fissile isotopes such as cross-section is much higher for the high-Z materials such as uranium-233, uranium-235 or plutonium-239 or plutonium lead, bismuth, thorium and uranium although the threshold 241. These gammas are energetic enough to photo-dissociate energy must be over 8 or so MeV. These energies are the nuclei of beryllium, deuterium and tritium as well as the binding energy for the least bound neutrons in found in 35 high-Z bismuth, thorium and or uranium. The nature. Further particle collisions with these materials will first generation neutrons produced from the interactions of also cause neutrons to be produced by the n.2n reaction as the electron beam with the spiked LBE or non-spiked LBE, well as from the electron generated gamma,n reactions. The can be moderated to a thermal spectrum by spectrum shaping novel idea includes the use of gamma emitting isotopes to alloys, and after moderation are most likely to interact with produce energetic gamma radiation in combination with 40 selected fissile material by neutron capture and fission. Sec gamma produced from energetic electrons. The gamma pho ond generation neutrons are produced by fission are energetic tons are energetic enough to cause neutrons to be ejected from and will escape the liquid target area without interacting with the nuclei of common isotopes, -19, -14 for the fissile material in the target and without interacting with example to produce positron emitting isotopes, fluorine-18 the LBE. Some of second generation neutrons can be and nitrogen-13 for example in commercial quantities as well 45 reflected back to the target by the reflector made of beryllium, as other valuable isotopes including actinium-225 by means beryllium deuteride, beryllium triteride, or heavy water pro of the gamma,n reaction. The gamma emitting alloy is engi ducing thermalised neutrons to drive fission reactions in the neered computationally to slow neutrons down to epithermal spiked LBE embodiment. The reflected second generation energies where captures are most likely in the gamma emit neutrons become low energy neutrons and will interact with ting alloy, containing Vanadium-50 and nickel-61 and others 50 the fissile material in the target with high probability. The like this one that emit energetic photons. The target for the reaction set will amplify without becoming critical because production of isotopes is the selected common isotope and the amplification is dependent upon continuous input of precursor material for each of the desired positron emitting gamma radiation from the electron beam, because the fissile isotopes to be produced. mass is non-critical and the geometry is well considered when As noted, the spectrum shaping alloy material facilitates 55 the mass and density of the selected fissile material(s) in the efficient neutron capture by the gamma emitting isotope in the metal matrix is Sufficient. selected resonance energy regions. This maximizes the pro Additional gammas are provided by the interior of the duction of the desired gammas of high intensity. The spec target containing the spiked or unspiked LBE. The part of the trum shaping material can be a hydrided or deuterated alloy or target that surrounds the LBE is comprised of erbium-nickel an oxide strengthened alloy or an alloy containing carbides, 60 alloy which emits energetic and penetrating gamma radiation nitrides or other neutron scattering material that shapes or in excess of8 MeV for each neutron captured by eacherbium tailors the spectrum appropriately, each spectrum shaping 167 nuclei. This alloy is also an excellent conductor of heat to alloy being specifically formulated to shape or tailor the spec provide cooling for the LBE. More energetic gammas are trum to maximize production of gammas in the selected provided by the capture in erbium-167 than what is produced gamma emitting isotope. One particularly effective scattering 65 by the electron beams. The gammas from erbium-167 are alloy is composed of very fine particles of borontetra carbide energetic enough to photo-dissociate more than one nuclei of (B4C) dispersed in aluminum silumen or vanadium-nickel, beryllium, deuterium or tritium that may be encountered. US 8,625,731 B2 7 8 Also the erbium-nickel 'cup' that holds the LBE has heavy material. Additional neutrons can be produced in a Surround water circulating in it. Heat is generated from the electron ing the Sub-critical assembly. The generator will not sustain a beam and from fission in the target. Heat is removed by nuclear chain reaction because the fissile materials are care pumping heavy water through the Vanadium-erbium-nickel fully distributed and are too low of mass to Support an uncon alloy that functions as the structural material to hold the 5 trolled chain reaction. The device is activated electrically so spiked or unspiked LBE. Since erbium nickel is an excellent that the produced stream of neutrons can be conveniently conductor of heat and since the working fluid for heat trans turned on and off to suit the needs of the application. port is heavy water, D2O, heat is managed well and additional The electronbeam area of the neutron generator consists of neutrons are produced via gamma,n reactions from the D2O. an evacuated tube made from a commercially available com The heavy water is pumped through the interior element of 10 the target to transportheat to the heat exchanger outside of the ponents. At the top end of the evacuated tube the electrons or apparatus to keep the operating temperature of the neutron alpha particles are gathered, excited and are accelerated by generator within satisfactory ranges. the electronic package to the target. The electrons or alpha Each embodiment of the invention discloses the novel ions are accelerated in the evacuated tube by electrostatic apparatus that produces significant quantities of neutrons out 15 field effects, electrical effects and/or magnetic means to a side of the conventional nuclear reactor or neutron generators high velocity near 99.99c (99.99% of the speed of light). The using fusion reactions of tritium and deuterium, or using energy of the electron beam should be between two and four alpha emitters on beryllium. The produced neutrons can be times the Giant Resonance region of the targeted material for used to transmute isotopes using the n.2 reaction, the n,3n the gamma,n reaction to occur within that material. Beryllium reaction and or the gamma,n reaction. Further, significant and deuterium have the lowest gamma,n threshold energies amounts of gamma radiation for direct conversion to direct known, 1.67 MeV and 2.24 MeV respectively. The Giant current is available. The neutrons or the produced gamma Resonance energy region for these reactions in these materi radiation could be used to transmute many unstable isotopes als spans energies of 2.0 million electron volts (2.0 MeV) to commonly known as “fission products to shorter lived radio ten million electron volts (10 MeV). Electrons having a veloc active isotopes or to stable non-radioactive isotopes. Numer 25 ity of 99.99c have an energy often million electron volts (10 ous medical and commercial isotopes, especially the positron MeV). emitting isotopes, can be produced using the gamma,n reac At the bottom end of the evacuated beam tube, the 10 MeV tion. Energetic gammas eject neutrons from the nuclei of electron beam interacts with the target matter the selected target isotopes to make important future commercial medical converter alloy of refractory elements, tantalum, tungsten isotopes. The gamma photons can produce a usable electric 30 rhenium and niobium or the beam interacts with high-Z mate current by the photoelectric effect for direct electrical pro rials, lead, bismuth, thorium and uranium with optimized duction in other embodiments. amounts of selected fissile materials comprising the spiked Depending on the application, this device produces neu LBE. In all embodiments there is a subcritical mass, density trons up to 5x10'' (5x10sup.14) neutrons per second with and geometry when the LBE is spiked with fissile material as about 250 kilowatts of thermal output that is managed by the 35 set out above in another embodiment and in the preferred cooling system. These neutrons have a different spectrum embodiment High-Zbismuth lead eutectic is used with out than the thermal or fast fission spectra. Copious high energy fissile material, with a low Z neutron source materials such as neutrons are produced with a significant population above beryllium in the LBE target and deuterium in the heavy water eight million electron volts (8 MeV). The output of the neu coolant to provide the neutrons in response to the gamma trons can be modulated by changing the pulse rate of the 40 photons produced from the activated electron beam or from electron beam so that as fewer pulses per second occur, to the vanadium-50-nickel-58-erbium-167 alloy or from palla reduce the neutron production rate. Cooling is achieved by dium-105 and palladium-107 deuteride in compartments in circulating heavy water or other selected coolants through the the target assembly. interior of the target, specifically the Vanadium-erbium When alpha particles are used at high enough energy, spal nickel alloy that readily absorbs neutrons, conducts heat well 45 lation neutrons are produced from the LBE. These neutrons and provides high energy gamma radiation in return. interact with the gamma emitting alloys. This embodiment of The structural components of the target preferably com the neutron generator can produce its neutrons from pow prise a vanadium-nickel-erbium alloy which transfers heat dered beryllium dispersed in an aluminum “lamp shade sur efficiently and from which energetic and penetrating gamma rounding the exterior of the generator with out the need for the radiation is produced when neutrons are captured. This 50 use of fissile materials in the generator. An aluminum clad gamma radiation is produced from thermal epithermal neu powdered beryllium “lampshade' would reflect neutrons tron capture in erbium-167 for the most part. These gammas from the interior to Sustain production of energetic gammas in are energetic enough to photo dissociate neutrons from nuclei the erbium alloy driving photo-dissociation reactions in the of beryllium or deuterium. These photo produced neutrons beryllium powder portion of the “lamp shade.” will be in the thermal spectrum and will cause uranium-233, 55 The electronics package 270 contemplates the use of any uranium-235, plutonium-239, or -243m to fission. Suitably charged particles: electrons, protons, deuterons and These produce fission spectrum neutrons that are too ener alpha particles, depending on the application and the effec getic to cause a chain reaction and they escape from the target tiveness of each charged particle to produce the desired reac compartment(s) containing the selected fissile materials. tion. The target generates the neutrons upon stimulation from The embodiments of this neutron generator include trans 60 bombardment of the relativistic electrons after the electrons portable devices that are electrically energized; allowing neu are converted to X-rays and after the X-rays interact with tron production to cease shortly after the generator's electron deuterium and beryllium. The LBE spiked target is uranium beam is de-energized. The first generation neutrons are pro 235, uranium-233 or plutonium-239, plutonium-241 or duced in the target from energetic X-rays above 5 MeV by the americium-243, or any combination thereof (as the fissile displaced electrons in the high-Z, LBE or LBE containing 65 neutron Source) with, beryllium, deuterium or tritium, or a thorium and uranium spikes also with spectrum shaping combination thereof (as the non-fissile neutron Source) in one alloys and computationally optimized amounts of fissile embodiment. The target geometry and target mass are calcu US 8,625,731 B2 10 lated computationally, optimized and engineered so that the side of the target. These materials “shed neutrons when target assembly and its components are highly Sub-critical at exposed to high energy gamma radiation. The 'shed neu all times. trons' are the product of the generator and escape the target The accelerated electrons interact with the high-Z materi area. These can be captured by a covering of gamma emitting als, uranium, plutonium or americium to produce energetic isotopes for the production of medical isotopes placed outside X-rays or in the preferred embodiment to produce X-rays in a of the beryllium lampshade. If power is to be produced, the lead bismuth eutectic. These X-rays are powerful enough to covering of gamma emitting isotopes is, in turn, covered by dissociate beryllium nuclei by the gamma,n reaction when the photo electric materials that produce a direct current from the emitted energy is above 1.67 MeV. The target may include a gamma photons like -, cadmium tel chamber containing beryllium di-deuteride or lithium beryl 10 lurium, cesium iodide plus . A different lium tri-deuteride and tri-triteride or palladium deuteride. The embodiment of the neutron generator is used for the produc gammas produced from the electron beam will dissociate tion of commercial or medical isotopes by the use of the deuterium nuclei (as well as the beryllium nuclei) by the gamma.neutron reaction. The generator neutrons are cap gamma,n reaction when the energy of the gamma is above tured outside of the target by the gamma emitting target 2.24 MeV. Higher energy gammas will be produced by cap 15 comprised of isotopes such as Vanadium-50 Vanadium-51, ture reactions in the target where neutrons are captured by nickel-58 and nickel-61 and erbium-167 that emit energetic erbium-167. These gammas exceed 6 MeV which can photo and penetrating gamma radiation when neutrons are cap dissociate more than one nuclei of beryllium or deuterium but tured. These alloys are placed in close proximity to target will interact with high-Z materials such as lead, bismuth, isotopes and the transmutation reactions result as the gamma thorium and uranium to produce neutrons more efficiently. photons interact with nuclei of the target isotope by causing To recapitulate and further clarify the teaching of this dis neutrons to be ejected from the nuclei of the targets. closure: There are three energy “generations” for the neutrons All of the preferred embodiments of the neutron generator produced by the target and four energy “generations of gam of the present invention employ isotopes that have large cap aS. ture cross sections for neutrons and emit very energetic The first generation neutrons are produced by the gamma,n 25 gamma photons. These include Vanadium isotopes, vana reaction as a consequence of the high energy electron beam dium-50 and vanadium-51 nickel isotopes, nickel-59 and interacting with the converter material and high-Z target Such nickel-61, the iron isotopes iron-57 and iron-54, europium as lead, bismuth, thorium or uranium. isotopes europium-152 and europium-154, erbium isotopes The second generation neutrons are produced from fission including erbium-167, gadolinium isotopes and bromine iso in one embodiment. 30 topes. The nuclei of these isotopes emit very energetic gam The second or third generation neutrons, depending on the mas when neutrons are captured. These attributes allow alloys presence or absence of fissile material in the target, are from to be engineered from combinations of these isotopes and the higher energy gamma,n reactions from erbium, nickel and computationally optimized to produce cascades of penetrat Vanadium acting on high-Z materials, lead, bismuth, thorium ing gamma radiation that is useful for isotope production, and uranium. The gammas are from the electron beam and 35 electrical energy production and other national security appli from neutron capture in erbium, nickel and Vanadium. Each cations. The Vanadium isotopes, Vanadium-50 and Vanadium has its characteristic wavelength. These gammas cause photo 51, produce gammas in excess of eleven million electron Volts dissociation in the heavy water coolant as well, in compart (11 MeV). The nickel isotopes, nickel-59 and nickel-61 pro ments containing either beryllium or deuterium and in the duce photons whose energy is in excess often million elec exterior beryllium-containing aluminum lampshade. 40 tron volts (10 MeV). The europium isotopes produce photons The first generation neutrons, those produced by the inci whose energy in excess of eight million electron Volts (8 dent accelerated particles, have energy in or near the thermal MeV). Erbium produces gammas in excess of seven million neutron range. These primary neutrons will interact with the electron volts (7 MeV). The iron isotopes provide energetic nuclei of the fissile materials and will cause the fissile mate photons as do certain -105 paladium rial in the target to fission with known probabilities in one 45 107, bromine-79 and gadolinium-155 and gadolinium-157. embodiment. The resulting fissioning will produce energetic Each neutron captured by the above mentioned isotopes of neutrons and fission fragments. Some of these neutrons will Vanadium, nickel, palladium, bromine gadolinium, bromine escape from the target and others will interact with the beryl and/or iron causes highly energetic gammas to be emitted lium nuclei to either produce additional neutrons or will be from the nuclei. These gammas are penetrating and useful and thermalised to be captured by fissile materials and cause 50 the composition of the alloys can be optimized using these fission with a Keff below 1. The liquid metal alloy compris materials. The alloys comprising the invention, the gamma ing the beam target is electrically conductive so that the emitting alloys, will also contain materials that slow high electronbeam can be maintained indefinitely. The LBE target energy neutrons produced from fission For example, Vana is arrayed like a wick inside a candle made from thoria dium-50, Vanadium-51, nickel-59, nickel-61, iron-57 and containing Zirconium hydride or other refractory material. 55 iron-54 can be placed under a beryllium and lead shell that The tube of electrically insulating material surrounds the reflects produced neutrons back below the reflecting shell but target at the down end of the evacuated tube and the down end allowing the gamma stream freely through the beryllium shell comprised of the vanadium-nickel-erbium alloy that holds the for applications outside of the neutron generator. On the liquid metal LBE, as if it were a deep cup. The target is cooled inside of the inventive neutron generator in the central region by circulating heavy water through the deep cup comprising 60 proximate to the electron beam target is placed a layer of the gamma emitting alloy. This provides for the production of palladium, titanium, or erbium infused with tritium and deu gammas boosting the yield from the electron input. terium. This matrix will generate secondary neutrons and will The deuterium in the coolant circulating through the deep moderate fission spectrum neutrons. cup provides additional neutrons from the gamma,n reac Beryllium-9 dissociates into a neutron and two alpha par tions. These neutrons will be captured by erbium in the target 65 ticles when it is hit with an energetic neutron whose collision to produce energetic gamma photons Sufficient to effectively energy is more than 1.67 million electron volts or when (with dissociate nuclei of deuterium and beryllium positioned out less likelihood) the beryllium nuclei interact with a gamma US 8,625,731 B2 11 12 photon having an energy of more than 1.67 million electron other equivalents and alternatives are intended to be included Volts. Deuterium dissociates into a neutron and a proton when within the scope of the present invention. it is hit with an energetic neutron whose collision energy is What is claimed as invention is: more than 2.24 million electron volts. There will be an 1. A compact neutron generator, comprising: increase in the population of neutrons cause by the multipli an electron beam source: cation effects of the levels of energies of the gamma photons a power rod at which an electron beam from said electron and the presence offissile material in the target. This feedback beam source is directed, said power rod including at will contribute to gamma production and may obviate the least one neutron multiplying material; need for continual input of electrons from the beam to supply a target isotope; primary neutrons. Pulses may be more separated in time as 10 at least one neutron spectrum shaper disposed between said the neutronic feedback effects increase the neutron produc neutron multiplying material and said target isotope; and tion rate. at least one cooling channel disposed around said at least The various examples disclosed in this patent application one spectrum shaper and through which a coolant is are generally called embodiments of the neutron generator. pumped. The gamma,n effects will produce additional neutrons from 15 2. The apparatus of claim 1, wherein said power rod target materials that are available for capture by the gamma includes high-Z material. emitting isotopes in the target. These neutrons will come from 3. The apparatus of claim 1, wherein said high-Z material is the beryllium nuclei or the deuterium or tritium nuclei or liquid lead bismuth eutectic. both. The neutrons will be slowed to the epithermal and 4. The apparatus of claim 3, wherein said LBE is spiked thermal energies where capture by the gamma emitting iso with neutron multiplying material. tope is most probable or where fission is most probable. 5. The apparatus of claim 1, including one neutron spec The gamma emitter alloy contains vanadium-50, vana trum shaper, wherein said neutron spectrum shaper contains dium-51, nickel-59, nickel-61, iron-57 or iron-54, or bro LBE. mine-79, and selected lanthanides such as europium and/or 6. The apparatus of claim 1, including first and second erbium that are deuterated or tritiated for secondary and/or 25 neutron multiplying materials, and first and second neutron tertiary neutron production. spectrum shapers. The present invention considers the neutronic properties of 7. The apparatus of claim 6, wherein said generator is the materials as well as the metallurgical aspects of the target Substantially cylindrical, and wherein said first neutron mul alloy to optimize the production of neutrons for various func tiplying material is disposed in the general center of the tions adjacent to the generator. 30 cylinder, said first neutron spectrum shaper is axially dis Another potential use of the inventive neutron generator is posed around said first neutron multiplying material, said for power production applications, i.e., for motive power from target isotope is axially disposed around said first neutron direct conversion of gamma photons to electrical power. The spectrum shaper, said second neutron spectrum shaper is gamma photons stimulate the movement of electrons taking axially disposed around said target isotope, and said second advantage of the photoelectric effects to convert the nuclear 35 neutron multiplying material is axially disposed around said energy, the gamma radiation, directly to electrical energy for second neutron spectrum shaper. motive power or other purposes. The high energy gammas 8. The apparatus of claim 7, further including a reflector produce pairs of electrons and holes in selected materials. The axially disposed around said second neutron multiplying distribution of the energies of the neutrons leaving the target material so as to reflect second generation neutrons. is managed and controlled by the thickness of the neutrons 40 9. The apparatus of claim 7, further including one or more average traverse through the alloys comprising the target, the cooling channels disposed between one or more of said first geometry of the shaping alloy and the neutron scattering and and second neutron multiplying materials, said first and sec slowing down properties engineered into the shaping or tai ond neutron spectrum shapers, and said target isotope. loring alloy for energetic gamma production to make neu 10. The apparatus of claim 7, further including a reflector trons available outside the target. The target alloy will include 45 axially disposed around said first and second neutron multi two or more gamma emitters having markedly different neu plying materials converters. tron capture cross sections so that as the neutrons slow down 11. The neutron generator of claim 10, wherein said reflec they will have opportunity to interact by capture reactions in tor is fabricated from a beryllium alloy. two or more gamma emitting isotopes. The lanthanides have 12. The neutron generator of claim 11, wherein said beryl the largest cross sections and will capture neutrons at lower 50 lium alloy is beryllium deuteride. energies very efficiently. The gammas produced will generate 13. The apparatus of claim 1, wherein said at least one more neutrons from the neutron donor materials. neutron spectrum shaper includes a gamma emitting alloy The action of an electron beam may be optimized in the that includes spectrum shaping additives for slowing high alloy to produce secondary neutrons by particle interactions energy neutrons to energies in the epithermal or thermal neu and by the photo nuclear effects caused by high energy 55 tron spectrum. gamma radiation. 14. The apparatus of claim 13, wherein said neutron spec Having fully described several embodiments of the present trum shaper includes a metal matrix fabricated from metal invention, many other equivalents and alternative embodi hydride material. ments will be apparent to those skilled in the art. These and ck ck ck ci: C