CA1061744A - Method for the separation of intermixed isotopes - Google Patents
Method for the separation of intermixed isotopesInfo
- Publication number
- CA1061744A CA1061744A CA236,760A CA236760A CA1061744A CA 1061744 A CA1061744 A CA 1061744A CA 236760 A CA236760 A CA 236760A CA 1061744 A CA1061744 A CA 1061744A
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- Prior art keywords
- mixture
- isotopes
- isotope
- wave
- vaporous
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000000926 separation method Methods 0.000 title description 4
- 239000000203 mixture Substances 0.000 claims abstract description 29
- 238000006243 chemical reaction Methods 0.000 claims abstract description 22
- 230000005284 excitation Effects 0.000 claims abstract description 22
- 238000001816 cooling Methods 0.000 claims abstract description 7
- 239000000126 substance Substances 0.000 claims description 21
- 238000002156 mixing Methods 0.000 claims description 8
- 238000009833 condensation Methods 0.000 claims description 5
- 230000005494 condensation Effects 0.000 claims description 5
- 238000010494 dissociation reaction Methods 0.000 claims description 5
- 230000005593 dissociations Effects 0.000 claims description 5
- 230000001678 irradiating effect Effects 0.000 claims description 5
- 238000004508 fractional distillation Methods 0.000 claims description 4
- 238000001845 vibrational spectrum Methods 0.000 claims description 3
- 230000006872 improvement Effects 0.000 claims description 2
- -1 polytetrafluoro-ethylene Polymers 0.000 claims description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 2
- 230000006837 decompression Effects 0.000 claims 1
- 229940058401 polytetrafluoroethylene Drugs 0.000 claims 1
- 230000003405 preventing effect Effects 0.000 claims 1
- CPELXLSAUQHCOX-UHFFFAOYSA-N Hydrogen bromide Chemical compound Br CPELXLSAUQHCOX-UHFFFAOYSA-N 0.000 description 16
- 150000001875 compounds Chemical class 0.000 description 9
- 229910000042 hydrogen bromide Inorganic materials 0.000 description 8
- 238000010521 absorption reaction Methods 0.000 description 7
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 7
- 230000005855 radiation Effects 0.000 description 6
- 239000007795 chemical reaction product Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 239000000047 product Substances 0.000 description 3
- 229910052770 Uranium Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005281 excited state Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000007805 chemical reaction reactant Substances 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000000053 physical method Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- JFALSRSLKYAFGM-OIOBTWANSA-N uranium-235 Chemical compound [235U] JFALSRSLKYAFGM-OIOBTWANSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D59/00—Separation of different isotopes of the same chemical element
- B01D59/34—Separation by photochemical methods
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biophysics (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physical Or Chemical Processes And Apparatus (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
Abstract
A B S T R A C T
This method for separating intermixed isotopes operates on the principle of selective excitation of one isotope, by means of a laser beam, and a chemical reaction, made possible thereby, of that isotope with a reaction partner. Based on that principle, this method, broadly stated, is distinguish-ed by a step-wise excitation of the one isotope and takes place after de-compressing and cooling down the mixture to below 100°K.
This method for separating intermixed isotopes operates on the principle of selective excitation of one isotope, by means of a laser beam, and a chemical reaction, made possible thereby, of that isotope with a reaction partner. Based on that principle, this method, broadly stated, is distinguish-ed by a step-wise excitation of the one isotope and takes place after de-compressing and cooling down the mixture to below 100°K.
Description
10~
The present invention concerns a method for separating mixtures of substances, particularly of isotopes or isotope compounds, based on the principle of selective excitation, dissociation or ionization of the one substance, for instance to make possible a cnemical reaction with a separately fed-in other reaction partner. Such excitation can be brought about by means of electromagnetic waves, particularly by laser radiation, the frequency of which is adjusted so that the radiation is absorbed selectively by the isotope to be separated. Such a method has become known, for instance, from the German Offenlengungsschrift 1,959,767, laid open on June 3, 1971.
` Use of such methods has shown that in addition to the chemical reactions made possible by the selective laser excitation, which permit a normal separation of the reaction product which contains only the excited isotope, also other reactions take place which have an adverse effect on the desired degree of selectivity. Such other are caused by an overlap of the absorption bands, resonance interchange and thermally activated reactions.
The problem therefore arose, to improve this method so that, on the one hand, the selectivity is increased and, consequently, the yield is also improved substantially~
According to the present invention~ this problem is solved by decompressing the initially vaporous substances of the mixture adiabatically to temperatures below 100 X a~d irradiating them, still before they are con-densed, with an electromagnetic wave, preferably by a laser beam of suitable ` frequency located in a resonator. The electromagnetic wave is adjusted here as to bandwidth and frequency position in such a manner that the Q-branch of the rotational vibration spectrum of the substance to be excited, is covered. In this process, the cooling-down has the effect, and is pushed so far, that the molecular vibrations are largely frozen and the frequency ` distribution of the rotational energies is shaped so that the P- and R-branch . ~' -1- ~.
: : .
of the isotope that is not to be excited, does not overlap much with the Q-branch of the one to be excited. Furthermore, use is made here particularly of a step-wise excitation.
For a further explanation, this method is illustrated by the example of the separation of the uranium isotopes 235 and 238; it should be pointed out here, of course, that the application of this method is in no way limited thereby.
The action of the method according to the invention is based on the combination of two measures:
1) Lowering the temperature of the mixture to below 100 K.
Thereby, a very considerable narrowing of the absorption bands of the isotope mixture, in this case of UF6, is achieved, whereas at room temper-ature the absorption bands of both isotope compounds U 235 F6 and U 238 F6 overlap in a large range, so that irradiation, using a definite frequency by means of a laser would lead to an almost equal excitation of both isotope compounds. The obtainable selectivity is therefor low. However, due to the narrowing of these abso~ption bands particularly of the Q-branches ~ -obtained by the heavy cooling according to the invention, overlap between the Q-branches practically no longer exists or is greatl~ reduced. The absorption maxima of the two isotope compounds, plotted versus the frequency, are distinctly separated. This means, however, that if a laser frequency which corresponds to the absorption maximum of the uranium 235 F6-compound ~` is radiated, the other isotope compound uranium 238 F6 is practically not ~`~ excited, or only much more weakly so.
`~ 2) Stepwise excitation makes it possible to excite with the ~ .
~` relatively low frequencies at which the molecule exhibits strong absorption .~ .
(for infrared-active fundamentals and simple combination vibrations), and still to achieve the high excitation energy desired for seleetive chemical reaction. For this reason and by excitation in a resonator, one can get `: .
~ Z -2-174~
along with relatively little laser power. This can be smaller by several orders of magnitude than for the excitation of the same intensity in a single-quantum process of the same end energy, although stepwise excitation is usually possible with low losses, only if the power density is chosen so high that the activation rates are higher than the interfering deactivation rates (without stimulated emission). The excitation preferably takes place here with the fundamental frequency V3~ which is 624 cm for U 235 F6.
Depending on the availability of lasers, other vibrations, e.g., the combination vibration vl ~ V3 of the U 235 F6, can also be excited, however.
This stepwise excitation by means of the fundamental frequency is possible because the energy difference between the lower excitation levels are little different. Preferably, the U 235 F6 molecules at resonance are involved.
In cases where this share is too small, the number of collisions is set, by suitable choice of the density or less divergent direction of the flow, to values so high that the other molecules get into the state necessary for absorption during the stay in the reaction zone. The occupation density of the excited states is therefore increased.
According to one broad aspect of the invention there is provided ` a method for separating intermixed isotopes forming vaporous mixture which is irradiated by an electromagnetic wave having a wave length selectively absorbed largely by one of the isotopes so that one isotope is excited to be separated after selective chemical reactions with a chemical partner or selective dissociation or selective ionization~ wherein the improvement compr~ses cooling said mixture to temperatures below about 100 K and irradiating the cooled mixture by said wave.
According to another broad aspect of the invention there is provided an apparatus for separating vaporous intermixed isotopes by mixing them with a vaporous chemical partner to form a vaporous mixture which is irradiated by an electromagnetic wave having a wave length absorbed largely ; ~ ~ 3 -1()ti17~
by one of the isotopes so that that one isotope is excited and selectively chemically reacts with the chemical partner; said apparatus comprising an evacuated chamber, irradiating means for radiating a beam of said wave transversely through said chamber, nozzle means adjacent to said beam for ejecting a flat jet of said mixture into said chamber transversely through the beam, and means beyond said beam on its other side from said nozzle, for peeling of portions of said jet which failed to pass through said beam while allowing the portions that passed through the beam, to continue onward into said evacuated chamber.
The accompanying drawings sohematically show examples of suitable apparatus for practicing this method, the various figures being as follows:
Figure 1 in longitudinal section shows the complete apparatus;
Figure 2 shows an example of the laser used; and Figure 3 shows a modification of the Figure 2 laser.
As already mentioned, the two uranium isotope compounds U 235 F6 and U 238 F6 are to be separated in this example, and specifically, by means of a chemical reaction with hydrogen bromide as the chemical partner.
According to the separating apparatus schematically shown in Figure 1, the~ul~anium compounds are contained in the supply vessel 2 and the reaction partner is in the supply vessel 3. They are fed to distribution ` chambers 32 and 22 via valves 31 and 21, and get from there to a mixing chamber 23, which is followed by a slit-shaped discharge nozzle 24. The latter alread~ forms part of the vacuum chamber 1 which is equipped with cooling walls 14, 15 and 16. Unspent reaction partner as well as volatile reaction products can be exhausted from the chamber 1 via connected pumps -; S and 6. In front of the nozzle 24, the laser beam 4 goes lengthwise through the jet of vapor -3a-. - , . . :.. ,. . :,.. ~ . . :
~ 1744 issuing from the nozzle, which represents a mixture of UF6 and Hbr This laser beam 4 is generated in the laser device proper, see Figure 2, and is built up by mirrors 42 and 43 to values so high that the losses are equal to the energy supplied. The position of the walls of the vacuum tank 1 or its t~indow is between the mirrors (see Figure 2) as is indicated here by dashed lines l. In the interior of the vacuum vessel there is the peeler 11, which forms a slit-shaped nozzle and takes care that the particles coming from the zone of the laser radiation are separated from those coming from other zones o~ the jet.
l~ The vapor pressure of the UF6 is adjusted through temperature control in the supply vessel 2, to a value slightly above the total pressure in the mixing chamber 23 of 3300 Torr. The temperature of the reaction part-ner in the supply vessel 3 is assumed to be adjusted so that in the mixing chamber 23, a mixture temperature adjusts itself which is slightly above the condensation temperature at the desired UF6 partial pressure. For 300 Torr ~ partial pressure of the UF6, corresponding to a vessel temperature of 314 K, a - mixture temperature of 320 K is chosen. Then, the HBr gas must be fed-in with a temperature of 290 K. At that temperature, HBr has a vapor pressure of 15,000 Torr. The desired mixture ratio, the ratio of the molecule concentra-~0 tion UF6/HBr = l:lO, is set via the valves~31 and ~1. So that as few thermal ` reactions as possible take place in the mixing chamber, the latter, and there-ore, with a given throughput, the dwelling time, are kept as small as possible.The dwelling time is in the order of lO 3 seconds. In order to prevent reactions at the walls of the mixing chambers, these chambers are designed aerodynamically (not shown) in such a manner that the correct mixture ratio occurs only in the zone of the vapor jet which is to be engaged later by the laser bea~. In praticular, there should be as little UF6 as possible in the outer zones. By lining the walls of these mixing parts with plastic, e.g., with polytetrafluoroethylene ~Teflon), catalytic action by them to release chemical reactions is largely prevented. Through these measures, clogging of ~,~ ~""~k :-17~
of the narrow discharge slit is prevented and the peeled-off UF6 portion, which was not engaged by the laser beam, is reduced. The walls of the nozzle passages may be heated to temperatures higher than that of the substances 10w-ing through the passages to prevent condensation at the walls of the nozzle.
The discharge nozzle 24 is a slit about 1/100 mm wide and 50 cm long and opens into the vacuum tank 1. The mixture jet is heavily decompres-sed adiabatically in the process and expands at the same time considerably in space~ As wall friction cannot occur here, considerable cooling-down occurs.
With an adiabatic coefficient for HBr of 1.42, a lowering of the pressure by tho factor 10 is sufficient to lower the temperature of the vapor jet to about 20 K. It should be pointed out at this point that it is generally advisable to choose reaction partners with adiabatic coefficients as large as possible, so that the required low temperature is reached with a lowering of the pressure of as little as possible. This can be accomplished, of course, also by means of a substance which does not participate in the reaction. In this process, the already mentioned heavy concentration of the Q-branch of the rotational vibration spectrum takes place and as a consequence, high selectivity. This condition occurs about 2.5 mm behind the discharge opening 24, and at this point runs, parallel to the nozzle 24, the laser beam, which - -is about 3 mm thick and whose frequency range should cover also the entire Q-branch including the shifting of the bands with increasing excitation stages.
(With increasing numbers of excitation stages, the excitation frequencies become somewhat lower). The central part of the gas jet issuing from the noz-zle 24 goes through the laser beam and is selectively excited here in steps.
As the quanta generated by stimulated emission are returned to the laser beam ~ ~ .
the excitation takes place with relatively high efficiency. The energy density of the laser beam is chosen here so that with the existing cross ;
section and a sufficiently high number of collisions in the region of the laser beam (about 50 collisions of each molecule), just the essential part of the U 235 F6 is reacted. Due to the great selectivity, only a small part of _ 5 _ ~..
-1(~6174~
the isotope compound U 238 F6 is reacted, as the reactive high excitation levels of molecules of this isotope are only lightly occupied.
The already mentioned peeler 11 lets through only that part of the jet which has gone through the laser beam, and the other part is either condensed (the UF6 at the cooling walls 14) or is pumped off (the HBr via the pump 5). The mixture of reaction products and starting materials that flies or ejects through the peeler, can be separated by fractional distillation.
On tl~e collector plate 16, enriched reaction products 7 are precipitated;
these consist, for instance, of enriched UF5 or UF4. Then, mainly U 238 F6 is condensed at the cooling walls 15. The volatile products such as, for in-stance, HF and HBr are exhausted via the pump 6. It would also be possible to freeze-out HBr and to bind the ~E chemically.
~; Essential for the described operation of this apparatus is that the jet of substance is still in vapor form in the region of the nozzle 24, i.e., not yet condensed. Substantial condensation takes place only when the jet of substance hits a cooled wall, as the heat of condensation must be removed, which is not possible because of the low density of the jet of sub-stance in the region of the laser radiation, the power density of which is ; about 103 watts/cm2.
In Figure 3 a lasex arrangement similar to Figure 2 is shown, in which a second additional laser 44 is provided, the radiation 4' of which is kept in the resonance s~stem formed by the mirrors 46 and 45. The lasers 41, 44 and their rsdiations 4, 4' axe arranged practically on the same axis and are shown mutuall~ displaced only to clarify the ray pakh~ A second such laser is advantageous if, starting from a selectively excited state, a still higher excitation, dissociation or ionization of the isotope molecules is to be brought about. The generated products can then be separated from each other in a manner known per se by chemical and/or physical methods. Examples for this are: Selective chemical reaction, possibly connected with subse-3 30 quent fractional distillation, fractional distillation of the dissociation ~: . . : . : .
7~
products, and deflection of the selectively produced ions in an electric and/or magnetic field.
Depending on the choice of the flow and radiation parameters, very high degrees of enrichment and very low residual contents can be obtained by the above methods. With the parameters given, one obtains an enrichment to about 22%, a residue content of 0.08% as well as an effective UF6 throughput of about 30 tons per year.
In conclusion, it should be mentioned that this method, which was described in connection with the separation of isotopes, can also be used for 1~ the preparation of chemical compounds which can otherwise be produced only ~ith difficulty or with low yield.
`~ ' .
.', : "
' ~.
' .
,, . ' ' ' ' ~ .
,
The present invention concerns a method for separating mixtures of substances, particularly of isotopes or isotope compounds, based on the principle of selective excitation, dissociation or ionization of the one substance, for instance to make possible a cnemical reaction with a separately fed-in other reaction partner. Such excitation can be brought about by means of electromagnetic waves, particularly by laser radiation, the frequency of which is adjusted so that the radiation is absorbed selectively by the isotope to be separated. Such a method has become known, for instance, from the German Offenlengungsschrift 1,959,767, laid open on June 3, 1971.
` Use of such methods has shown that in addition to the chemical reactions made possible by the selective laser excitation, which permit a normal separation of the reaction product which contains only the excited isotope, also other reactions take place which have an adverse effect on the desired degree of selectivity. Such other are caused by an overlap of the absorption bands, resonance interchange and thermally activated reactions.
The problem therefore arose, to improve this method so that, on the one hand, the selectivity is increased and, consequently, the yield is also improved substantially~
According to the present invention~ this problem is solved by decompressing the initially vaporous substances of the mixture adiabatically to temperatures below 100 X a~d irradiating them, still before they are con-densed, with an electromagnetic wave, preferably by a laser beam of suitable ` frequency located in a resonator. The electromagnetic wave is adjusted here as to bandwidth and frequency position in such a manner that the Q-branch of the rotational vibration spectrum of the substance to be excited, is covered. In this process, the cooling-down has the effect, and is pushed so far, that the molecular vibrations are largely frozen and the frequency ` distribution of the rotational energies is shaped so that the P- and R-branch . ~' -1- ~.
: : .
of the isotope that is not to be excited, does not overlap much with the Q-branch of the one to be excited. Furthermore, use is made here particularly of a step-wise excitation.
For a further explanation, this method is illustrated by the example of the separation of the uranium isotopes 235 and 238; it should be pointed out here, of course, that the application of this method is in no way limited thereby.
The action of the method according to the invention is based on the combination of two measures:
1) Lowering the temperature of the mixture to below 100 K.
Thereby, a very considerable narrowing of the absorption bands of the isotope mixture, in this case of UF6, is achieved, whereas at room temper-ature the absorption bands of both isotope compounds U 235 F6 and U 238 F6 overlap in a large range, so that irradiation, using a definite frequency by means of a laser would lead to an almost equal excitation of both isotope compounds. The obtainable selectivity is therefor low. However, due to the narrowing of these abso~ption bands particularly of the Q-branches ~ -obtained by the heavy cooling according to the invention, overlap between the Q-branches practically no longer exists or is greatl~ reduced. The absorption maxima of the two isotope compounds, plotted versus the frequency, are distinctly separated. This means, however, that if a laser frequency which corresponds to the absorption maximum of the uranium 235 F6-compound ~` is radiated, the other isotope compound uranium 238 F6 is practically not ~`~ excited, or only much more weakly so.
`~ 2) Stepwise excitation makes it possible to excite with the ~ .
~` relatively low frequencies at which the molecule exhibits strong absorption .~ .
(for infrared-active fundamentals and simple combination vibrations), and still to achieve the high excitation energy desired for seleetive chemical reaction. For this reason and by excitation in a resonator, one can get `: .
~ Z -2-174~
along with relatively little laser power. This can be smaller by several orders of magnitude than for the excitation of the same intensity in a single-quantum process of the same end energy, although stepwise excitation is usually possible with low losses, only if the power density is chosen so high that the activation rates are higher than the interfering deactivation rates (without stimulated emission). The excitation preferably takes place here with the fundamental frequency V3~ which is 624 cm for U 235 F6.
Depending on the availability of lasers, other vibrations, e.g., the combination vibration vl ~ V3 of the U 235 F6, can also be excited, however.
This stepwise excitation by means of the fundamental frequency is possible because the energy difference between the lower excitation levels are little different. Preferably, the U 235 F6 molecules at resonance are involved.
In cases where this share is too small, the number of collisions is set, by suitable choice of the density or less divergent direction of the flow, to values so high that the other molecules get into the state necessary for absorption during the stay in the reaction zone. The occupation density of the excited states is therefore increased.
According to one broad aspect of the invention there is provided ` a method for separating intermixed isotopes forming vaporous mixture which is irradiated by an electromagnetic wave having a wave length selectively absorbed largely by one of the isotopes so that one isotope is excited to be separated after selective chemical reactions with a chemical partner or selective dissociation or selective ionization~ wherein the improvement compr~ses cooling said mixture to temperatures below about 100 K and irradiating the cooled mixture by said wave.
According to another broad aspect of the invention there is provided an apparatus for separating vaporous intermixed isotopes by mixing them with a vaporous chemical partner to form a vaporous mixture which is irradiated by an electromagnetic wave having a wave length absorbed largely ; ~ ~ 3 -1()ti17~
by one of the isotopes so that that one isotope is excited and selectively chemically reacts with the chemical partner; said apparatus comprising an evacuated chamber, irradiating means for radiating a beam of said wave transversely through said chamber, nozzle means adjacent to said beam for ejecting a flat jet of said mixture into said chamber transversely through the beam, and means beyond said beam on its other side from said nozzle, for peeling of portions of said jet which failed to pass through said beam while allowing the portions that passed through the beam, to continue onward into said evacuated chamber.
The accompanying drawings sohematically show examples of suitable apparatus for practicing this method, the various figures being as follows:
Figure 1 in longitudinal section shows the complete apparatus;
Figure 2 shows an example of the laser used; and Figure 3 shows a modification of the Figure 2 laser.
As already mentioned, the two uranium isotope compounds U 235 F6 and U 238 F6 are to be separated in this example, and specifically, by means of a chemical reaction with hydrogen bromide as the chemical partner.
According to the separating apparatus schematically shown in Figure 1, the~ul~anium compounds are contained in the supply vessel 2 and the reaction partner is in the supply vessel 3. They are fed to distribution ` chambers 32 and 22 via valves 31 and 21, and get from there to a mixing chamber 23, which is followed by a slit-shaped discharge nozzle 24. The latter alread~ forms part of the vacuum chamber 1 which is equipped with cooling walls 14, 15 and 16. Unspent reaction partner as well as volatile reaction products can be exhausted from the chamber 1 via connected pumps -; S and 6. In front of the nozzle 24, the laser beam 4 goes lengthwise through the jet of vapor -3a-. - , . . :.. ,. . :,.. ~ . . :
~ 1744 issuing from the nozzle, which represents a mixture of UF6 and Hbr This laser beam 4 is generated in the laser device proper, see Figure 2, and is built up by mirrors 42 and 43 to values so high that the losses are equal to the energy supplied. The position of the walls of the vacuum tank 1 or its t~indow is between the mirrors (see Figure 2) as is indicated here by dashed lines l. In the interior of the vacuum vessel there is the peeler 11, which forms a slit-shaped nozzle and takes care that the particles coming from the zone of the laser radiation are separated from those coming from other zones o~ the jet.
l~ The vapor pressure of the UF6 is adjusted through temperature control in the supply vessel 2, to a value slightly above the total pressure in the mixing chamber 23 of 3300 Torr. The temperature of the reaction part-ner in the supply vessel 3 is assumed to be adjusted so that in the mixing chamber 23, a mixture temperature adjusts itself which is slightly above the condensation temperature at the desired UF6 partial pressure. For 300 Torr ~ partial pressure of the UF6, corresponding to a vessel temperature of 314 K, a - mixture temperature of 320 K is chosen. Then, the HBr gas must be fed-in with a temperature of 290 K. At that temperature, HBr has a vapor pressure of 15,000 Torr. The desired mixture ratio, the ratio of the molecule concentra-~0 tion UF6/HBr = l:lO, is set via the valves~31 and ~1. So that as few thermal ` reactions as possible take place in the mixing chamber, the latter, and there-ore, with a given throughput, the dwelling time, are kept as small as possible.The dwelling time is in the order of lO 3 seconds. In order to prevent reactions at the walls of the mixing chambers, these chambers are designed aerodynamically (not shown) in such a manner that the correct mixture ratio occurs only in the zone of the vapor jet which is to be engaged later by the laser bea~. In praticular, there should be as little UF6 as possible in the outer zones. By lining the walls of these mixing parts with plastic, e.g., with polytetrafluoroethylene ~Teflon), catalytic action by them to release chemical reactions is largely prevented. Through these measures, clogging of ~,~ ~""~k :-17~
of the narrow discharge slit is prevented and the peeled-off UF6 portion, which was not engaged by the laser beam, is reduced. The walls of the nozzle passages may be heated to temperatures higher than that of the substances 10w-ing through the passages to prevent condensation at the walls of the nozzle.
The discharge nozzle 24 is a slit about 1/100 mm wide and 50 cm long and opens into the vacuum tank 1. The mixture jet is heavily decompres-sed adiabatically in the process and expands at the same time considerably in space~ As wall friction cannot occur here, considerable cooling-down occurs.
With an adiabatic coefficient for HBr of 1.42, a lowering of the pressure by tho factor 10 is sufficient to lower the temperature of the vapor jet to about 20 K. It should be pointed out at this point that it is generally advisable to choose reaction partners with adiabatic coefficients as large as possible, so that the required low temperature is reached with a lowering of the pressure of as little as possible. This can be accomplished, of course, also by means of a substance which does not participate in the reaction. In this process, the already mentioned heavy concentration of the Q-branch of the rotational vibration spectrum takes place and as a consequence, high selectivity. This condition occurs about 2.5 mm behind the discharge opening 24, and at this point runs, parallel to the nozzle 24, the laser beam, which - -is about 3 mm thick and whose frequency range should cover also the entire Q-branch including the shifting of the bands with increasing excitation stages.
(With increasing numbers of excitation stages, the excitation frequencies become somewhat lower). The central part of the gas jet issuing from the noz-zle 24 goes through the laser beam and is selectively excited here in steps.
As the quanta generated by stimulated emission are returned to the laser beam ~ ~ .
the excitation takes place with relatively high efficiency. The energy density of the laser beam is chosen here so that with the existing cross ;
section and a sufficiently high number of collisions in the region of the laser beam (about 50 collisions of each molecule), just the essential part of the U 235 F6 is reacted. Due to the great selectivity, only a small part of _ 5 _ ~..
-1(~6174~
the isotope compound U 238 F6 is reacted, as the reactive high excitation levels of molecules of this isotope are only lightly occupied.
The already mentioned peeler 11 lets through only that part of the jet which has gone through the laser beam, and the other part is either condensed (the UF6 at the cooling walls 14) or is pumped off (the HBr via the pump 5). The mixture of reaction products and starting materials that flies or ejects through the peeler, can be separated by fractional distillation.
On tl~e collector plate 16, enriched reaction products 7 are precipitated;
these consist, for instance, of enriched UF5 or UF4. Then, mainly U 238 F6 is condensed at the cooling walls 15. The volatile products such as, for in-stance, HF and HBr are exhausted via the pump 6. It would also be possible to freeze-out HBr and to bind the ~E chemically.
~; Essential for the described operation of this apparatus is that the jet of substance is still in vapor form in the region of the nozzle 24, i.e., not yet condensed. Substantial condensation takes place only when the jet of substance hits a cooled wall, as the heat of condensation must be removed, which is not possible because of the low density of the jet of sub-stance in the region of the laser radiation, the power density of which is ; about 103 watts/cm2.
In Figure 3 a lasex arrangement similar to Figure 2 is shown, in which a second additional laser 44 is provided, the radiation 4' of which is kept in the resonance s~stem formed by the mirrors 46 and 45. The lasers 41, 44 and their rsdiations 4, 4' axe arranged practically on the same axis and are shown mutuall~ displaced only to clarify the ray pakh~ A second such laser is advantageous if, starting from a selectively excited state, a still higher excitation, dissociation or ionization of the isotope molecules is to be brought about. The generated products can then be separated from each other in a manner known per se by chemical and/or physical methods. Examples for this are: Selective chemical reaction, possibly connected with subse-3 30 quent fractional distillation, fractional distillation of the dissociation ~: . . : . : .
7~
products, and deflection of the selectively produced ions in an electric and/or magnetic field.
Depending on the choice of the flow and radiation parameters, very high degrees of enrichment and very low residual contents can be obtained by the above methods. With the parameters given, one obtains an enrichment to about 22%, a residue content of 0.08% as well as an effective UF6 throughput of about 30 tons per year.
In conclusion, it should be mentioned that this method, which was described in connection with the separation of isotopes, can also be used for 1~ the preparation of chemical compounds which can otherwise be produced only ~ith difficulty or with low yield.
`~ ' .
.', : "
' ~.
' .
,, . ' ' ' ' ~ .
,
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for separating intermixed isotopes by forming a vaporous mixture which is irradiated by an electromagnetic wave having a wave length selectively absorbed largely by one of the isotopes so that one isotope is excited to be separated after selective chemical reactions with a chemical par-tner or selective dissociation or selective ionisation; wherein the improve-ment comprises cooling said mixture to temperatures below about 100°K and irradiating the cooled mixture by said wave.
2. The method of claim 1 in which said wave has a bandwidth and frequency covering a Q-branch of the rotational vibration spectrum of said one isotope.
3. The method of claim 2 in which the intensity of said wave and the density of said one isotope in said mixture are adjusted to obtain a step-wise excitation of that one isotope.
4. The method of claim 2 in which said mixture is irradiated simul-taneously by two electromagnetic waves having said wave lengths and formed by a resonant system powered by two lasers.
5. The method of claim 1 in which said mixture is cooled by being decompressed adiabatically by ejection through a slit-shaped nozzle orifice.
6. The method of claim 1 in which said mixture and its chemical partner are decompressed in two different nozzles.
7. The method of claim 5 in which the cooled and irradiated mixture is ejected into a vacuum chamber and its vaporous components are condensed and separated by fractional distillation.
8. The method of claim 5 in which said vaporous intermixed isotopes and said vaporous chemical partner are separately conducted to said nozzle and mixed while ejecting through the nozzle or behind it.
9. The method of claim 7 in which the intermixed isotopes and partner are separately conducted to the nozzle through warm passages preven-ting their condensation.
10. The method of claim 7 in which said passages have polytetrafluoro-ethylene surfaces.
11. The method of claim 5 or 6 in which said mixture comprises a substance to achieve lower temperatures during decompression which substance does not undergo chemical reactions with any component of the mixture.
12. An apparatus for separating vaporous intermixed isotopes by mixing them with a vaporous chemical partner to form a vaporous mixture which is irradiated by an electromagnetic wave having a wave length absorbed largely by one of the isotopes so that that one isotope is excited and selectively chemically reacts with the chemical partner; said apparatus comprising an evacuated chamber, irradiating means for radiating a beam of said wave trans-versely through said chamber, nozzle means adjacent to said beam for ejecting a flat jet of said mixture into said chamber transversely through the beam, and means beyond said beam on its other side from said nozzle, for peeling of portions of said jet which failed to pass through said beam while allowing the portions that passed through the beam, to continue onward into said evacuated chamber.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2447762A DE2447762C2 (en) | 1974-10-07 | 1974-10-07 | Method and device for separating mixtures of substances and application of the same for the production of chemical compounds |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1061744A true CA1061744A (en) | 1979-09-04 |
Family
ID=5927735
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA236,760A Expired CA1061744A (en) | 1974-10-07 | 1975-09-30 | Method for the separation of intermixed isotopes |
Country Status (7)
| Country | Link |
|---|---|
| AU (1) | AU501570B2 (en) |
| CA (1) | CA1061744A (en) |
| DE (1) | DE2447762C2 (en) |
| FR (1) | FR2287262A1 (en) |
| GB (1) | GB1506766A (en) |
| IL (1) | IL47756A (en) |
| ZA (1) | ZA756033B (en) |
Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5015348A (en) * | 1972-06-14 | 1991-05-14 | Eerkens Jozef W | High mass isotope separation arrangement |
| DE2536940C3 (en) * | 1974-10-07 | 1983-12-08 | Kraftwerk Union AG, 4330 Mülheim | Device for separating isotope mixtures |
| DE2458563A1 (en) * | 1974-12-11 | 1976-06-16 | Uranit Gmbh | PROCESS FOR ISOTOPE SEPARATION BY USING LASER |
| US4734177A (en) * | 1975-11-26 | 1988-03-29 | The United States Of America As Represented By The United States Department Of Energy | Laser isotope separation |
| DE2609205A1 (en) * | 1976-03-05 | 1977-09-22 | Kraftwerk Union Ag | PROCESS FOR ISOTOPE SEPARATION WITH THE AID OF A COHERENT ELECTROMAGNETIC RADIATION |
| DE2621345A1 (en) * | 1976-05-14 | 1977-11-17 | Messerschmitt Boelkow Blohm | PROCESS FOR SEPARATION OF ISOTOPES WITH THE AID OF A LASER AND EQUIPMENT FOR CARRYING OUT THE PROCESS |
| DE2651306A1 (en) * | 1976-11-10 | 1978-05-11 | Kraftwerk Union Ag | PROCESS FOR THE SEPARATION OF GASEOUS ISOTOPE COMPOUNDS |
| US4439404A (en) * | 1976-12-03 | 1984-03-27 | Ga Technologies Inc. | Separation of uranium isotopes |
| DE2659590C2 (en) * | 1976-12-30 | 1985-03-21 | Kraftwerk Union AG, 4330 Mülheim | Process for isotope separation from gaseous mixtures of substances |
| JPS53100398A (en) * | 1977-02-15 | 1978-09-01 | Kyoto Daigaku Souchiyou | Method of separating uranium isotope by infrared rays |
| DE2718030C2 (en) * | 1977-04-22 | 1982-12-16 | Kraftwerk Union AG, 4330 Mülheim | Method and device for the photochemical separation of a mixture of substances |
| CA1100438A (en) * | 1977-08-10 | 1981-05-05 | Kyu C. Kim | Method and apparatus for controlled condensation isotope separation |
| DE2805958C3 (en) * | 1978-02-13 | 1981-03-19 | Kraftwerk Union AG, 4330 Mülheim | Nozzle for the adiabatic expansion of gases |
| DE2810791C3 (en) * | 1978-03-13 | 1985-06-05 | Kraftwerk Union AG, 4330 Mülheim | Method and device for separating a gaseous mixture of isotope compounds |
| DE2849162C2 (en) * | 1978-11-13 | 1986-02-20 | Kraftwerk Union AG, 4330 Mülheim | Device for carrying out the process for isotope separation according to patent 26 59 590 |
| US4199329A (en) * | 1978-11-20 | 1980-04-22 | Northrop Corporation | Process and apparatus for the removal of vaporized contaminants from closed gas system |
| FR2495493B1 (en) * | 1980-12-04 | 1985-06-28 | Westinghouse Electric Corp | PROCESS FOR SEPARATING URANIUM ISOTOPES |
| DE3438502A1 (en) * | 1984-10-18 | 1986-04-24 | Kraftwerk Union AG, 4330 Mülheim | Process and apparatus for separating off the product in the isotopic separation of uranium |
| DE4331267A1 (en) * | 1993-09-15 | 1995-03-16 | Uranit Gmbh | Multiple-orifice nozzle arrangement |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1391738A (en) | 1963-10-21 | 1965-03-12 | Comp Generale Electricite | Isotopic separation process |
| US3558877A (en) * | 1966-12-19 | 1971-01-26 | Gca Corp | Method and apparatus for mass separation by selective light absorption |
| DE1959767C2 (en) * | 1969-11-28 | 1982-12-23 | Battelle-Institut E.V., 6000 Frankfurt | Process for isotope separation |
-
1974
- 1974-10-07 DE DE2447762A patent/DE2447762C2/en not_active Expired
-
1975
- 1975-07-22 IL IL47756A patent/IL47756A/en unknown
- 1975-09-23 ZA ZA00756033A patent/ZA756033B/en unknown
- 1975-09-25 AU AU85193/75A patent/AU501570B2/en not_active Expired
- 1975-09-25 GB GB39430/75A patent/GB1506766A/en not_active Expired
- 1975-09-30 CA CA236,760A patent/CA1061744A/en not_active Expired
- 1975-10-06 FR FR7530546A patent/FR2287262A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| FR2287262A1 (en) | 1976-05-07 |
| GB1506766A (en) | 1978-04-12 |
| DE2447762A1 (en) | 1976-04-08 |
| FR2287262B1 (en) | 1979-02-02 |
| DE2447762C2 (en) | 1987-10-01 |
| IL47756A0 (en) | 1975-12-31 |
| ZA756033B (en) | 1976-08-25 |
| IL47756A (en) | 1978-03-10 |
| AU8519375A (en) | 1977-03-31 |
| AU501570B2 (en) | 1979-06-21 |
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