US3613989A - Gas centrifuges, their assembly and a process for enriching uranium 235 - Google Patents

Gas centrifuges, their assembly and a process for enriching uranium 235 Download PDF

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Publication number
US3613989A
US3613989A US768981A US3613989DA US3613989A US 3613989 A US3613989 A US 3613989A US 768981 A US768981 A US 768981A US 3613989D A US3613989D A US 3613989DA US 3613989 A US3613989 A US 3613989A
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Prior art keywords
gas
centrifuge
chamber
uranium
gases
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US768981A
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English (en)
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Yoshitoshi Oyama
Yoichi Takashima
Shigebumi Aoki
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Doryokuro Kakunenryo Kaihatsu Jigyodan
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Doryokuro Kakunenryo Kaihatsu Jigyodan
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    • 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
    • B01D59/20—Separation by centrifuging

Definitions

  • Pressured Source Hegting means Evacuattng Pump Depleted GaB Output
  • SHEET 10F 3 I Pressured Source 1st Orifice 1st t Means to rotate 1- Container 27 3
  • the prior art employs a process of centrifuging uranium hexafluoride having about 0.7 percent-uranium 235 comixed therewith in a rotor subjected to pressure diffusion and countercurrent separating and extracting thereby a gas of uranium 238 comprising a mass larger than the uranium hexafluoride and a gas of uranium 235 comprising a mass smaller than that.
  • This system necessitates taking out the two kinds of gases under precautions, to avoid their comixing.
  • To accomplish this some additional method has to be employed, which increases the difiiculties and expenses of production and demands on power.
  • the centrifuging process depends, essentially, upon differences between minute masses of isotopes (that is, small separation effect) and therefore, as a result, numerous operating steps of centrifuging are required in order to obtain moderately enriched uranium 235 (for example, about percent). Especially, as tremendous numbers of centrifuges are demanded in each early step, it is not desirable that the cold trap should be applied in each early process of centrifuging in which the gas will be close to natural.
  • An object of the present invention is to provide a gas centrifuging process and an apparatus for use directly in the process wherein uranium 235 is enriched and separated, without using a cold trap, from mixed gas of inert light gas with uranium hexafluoride which are fed as a starting material.
  • mixed gas of nearly an equal amount of uranium hexafluoride with inert light gas is fed into a rotor, rotating at a high velocity, so that the mixed gas may be separated into an enriched gas of uranium 235, depleted gas of uranium 235 and an inert light gas.
  • the separated inert light gas of a high purity is taken out through a hollow center shaft of the rotor and is circulated again around the outer surface of the rotor.
  • the pure inert light gas fed around the rotor is divided into an upper and a lower flow so that they are mixed respectively with the depleted uranium 235.
  • Enriched uranium 235 is jetted out through holes of the end plates of the rotor.
  • the mixed gas of enriched gas of uranium 235 with the inert light gas is fed to a rotor of the next step while the mixed gas of depleted gas of uranium 235 with the inert light gas is fed to a rotor of the former step as constructed to be cascade formation.
  • the ratio of the inert light gas, for example, helium gas, to the uranium hexafluoride to be fed into the rotor as mixed gas is changeable.
  • the ratio of the helium gas to the uranium hexafluoride is in the range of from 1 to l to 3 to I. If the amount of the helium gas is beyond this range, the cost for operating power cannot be disregarded.
  • the inert light gas in the rotor is to be collected in the center part of the rotor, it is taken out through another rotating hollow shaft from the rotor to the outside thereof so that it may be introduced into the space between the sidewall of the rotor and the fixed outer cylinder.
  • the size and position of small holes in the end plates of the rotor are arranged so accurately that the ratio of amount of uranium hexafluoride from the upper plate to that from the lower plate, to be jetted out through holes, respectively, is almost perfectly I to 1.
  • Each gas is then, mixed with the inert light gas introduced into the space between the sidewalls of the rotor and the cylinder so as to provide equal amounts by means of valve operation of suction pipes above and below the rotor.
  • the mixed gas of enriched uranium 235 with the inert light gas is fed to a rotor of the next step while the mixed gas of depleted gas of uranium 235 with the inert light gas is fed back to another rotor of the former step.
  • the gas material balance is such that the amount of the gas fed to a certain rotor is equal to the sum of the amount of the mixed gas of the enriched uranium 235 with the inert light gas from a rotor of the former step and that of the mixed gas of the depleted gas of uranium 235 with the inert light gas from a rotor of the next step.
  • the present invention provides for a cascade formation comprising a supply step as a center thereof with a plurality of enriching steps for enrichment of uranium 235 and a plurality of recovery steps for depleting uranium 235.
  • uranium hexafluoride gas of moderately enriched degree of uranium 235 is obtained from the enriching step without using a cold trap.
  • the uranium gas enriched to a higher degree gained from the successive enriching step is separated and may be enriched by using a cold trap because the amount of uranium gas handled becomes much smaller in the successive steps.
  • FIG. I is a cross-sectional view of a gas centrifuge unit of the invention with portion between the broken lines omitted, which unit is self sustaining but also may serve as the first, the last, or an intermediate unit of a cascade system of such units;
  • FIG. 2 is a view in cross section along lines II-II of FIG. I;
  • FIG. 3 is a flow sheet explaining the method of the invention.
  • FIG. 4 is a diagrammatical representation of the cascade system of and method and apparatus of the present invention.
  • FIGS. 1 and 2 are drawn to scale.
  • FIGS. 1 and 2 three helium gas feeding pipes 11 are shown radially connected at angular intervals of degrees to orifices in the central part of a long, fixed outer housing 10 on the outside thereof.
  • each pipe 11 has a small nozzle 12 within the respective orifice for control of helium flow rate of an angle suitable for aiming the flow in the same direction as the rotation of a rotor 20 and tangentially to the outer surface thereof.
  • Suction pipes 13 and 14, for separated gas having valve devices 15 and 16, respectively, are fixed respectively near both end regions of the fixed outer cylinder 10.
  • An elongated rotor 20 is fitted within said fixed outer housing and is supported with bearings 17 and 18, respectively, so as to be rotated in counterclockwise direction, indicated by the arrow, at such high velocity that its peripheral velocity reaches, for example, 350 meters/second.
  • An upper shaft 23 and a lower shaft 24 having a gas introducing port 23a and a gas pulling-out port 240 therein are integral with an upper end plate 21 and a lower end plate 22, respectively, so as to connect the inside of the rotor with the outside of the housing.
  • Conventional commutators are provided to connect airtight the rotating shafts with stationary feeding conduits.
  • the upper and lower end plates 21 and 22 have gas jetting small holes 25 and 26 therein, respectively.
  • the inside wall surface of the outer housing 10 opposite to the respective end plates 21 and 22 has circumferential flange-shaped projecting parts 27 and 28 so as to form with the end plates annular narrow clearance 31 and 32, respectively.
  • a heating device 41 and a cooling device 42, respectively, are provided at the upper and lower ends of the rotor.
  • a gas mixed in the ratio of 1:1 of uranium hexafluoride to helium gas is fed into the rotor through the gas introducing port 230 by a pump.
  • the mixed gas in the rotor is subjected to pressure diffusion by means of rotation of the rotor at a high velocity and is subjected to countercurrent flow by means of a heating device 41 and cooling device 42. Therefore, the arrangement in FIG. 1 forms a flow pattern as shown by arrows.
  • the position of the gas jetting small holes 25 and 26 is drawn to scale. Their size is calculated so that the ratio of amount of the gas, containing depleted uranium 235 as mixed, to be jetted through the holes 25 to a chamber A in FIG.
  • the helium gas collected in the axially central part of the rotor is pulled out through the gas pulling-out port 24a at a high purity and is then jetted through a valve device 19, tangentially to the outer surface of the rotor, into the circumferential chamber 50 through small orifices 12 at the tip of each feeding pipe so that the stability of the rotor, rotating at a high velocity is not disturbed and may be that the rotor is surrounded on the greater part of its outer surface with the helium gas.
  • the helium gas pulled out from the rotor to the outside thereof may be further purified before it is fed to the outside of the rotor, for example, by using a purification centrifuge.
  • the valve device 19 is, preferably, an automatic regulating valve with an inlet pressure arranged at a fixed pressure so that the amount of the helium gas to be jetted through the valve device corresponds at a predetermined ratio with that of the helium gas fed into the rotor for the first time.
  • metering means of the helium passing through the valve and of the newly introduced gas and means to control the supply by the output of the metering means may be interposed.
  • the helium gas sweeps out through annular clearance 31 and 32 into the chambers A and B, respectively, it is mixed respectively with the gases jetted out through the holes 25 and 26 and is then evacuated by vacuum pumps through pipes 13 and 14.
  • Means are provided to control the flow of the helium gas, divided into the upper and lower flow into amounts equal to each other by providing flow control arranging valve devices a and 160, respectively.
  • FIG. 3 shows a flow sheet of the process of the invention in a cascade formation through a plurality of centrifuging apparatus.
  • Each supply step Cf, enriching step C0,, CCg and Ccm, and recovery step Cr,, Cr, and Crn are combined with one another, so that each step may be arranged in parallel having a great number of centrifuges, especially, greater number thereof in the vicinity of the supply step and a decreasing number in the direction toward the last step.
  • FIG. 4 represents schematically the system of the invention in the combination of a plurality of centrifuges, showing the interconnections from the first supply centrifuge to the first recovery centrifuge, to the last recovery centrifuge with broken line indicating a chain of additional interposed recovery centrifuges and from the first supply centrifuge to the first enriching centrifuge and to the last enriching centrifuge with a broken line indicating a chain of additional interposed enriching centrifuges, each centrifuge having an additional helium purification centrifuge interposed between the output of its parent centrifuge and its feedback to it.
  • Every of these centrifuges is provided with its own three evacuating pumps, an enriched U-235 evacuating pump, a depleted U-235 evacuating pump and a helium pump, as shown in greater detail schematically in FIG. 1 only.
  • the mixing chamber shown in FIG. 4 is provided only for the first centrifuge. Only the last recovery centrifuge and the last enriching centrifuge each have an enriched Uranium output means and depleted uranium output means, respectively.
  • a gas centrifuge for separating and enriching mixtures of gases in accordance with minute differences between mass numbers ofisotopes comprising:
  • a rotary chamber coaxially situated within said outer housing, mounted rotatably thereto having an upper and a lower end-plate; the radius of said housing being larger than the radius of said rotary, the said housing and said rotary chamber thus providing a circumferential chamber in between their walls; said housing provided internally at the levels of said upper and lower end plates with flanges, forming with said plates an upper and lower jetting containers with jet inlets;
  • a first duct means including a first orifice in said housing to feed a mixture of gases into said rotary chamber through the upper end-plate thereof;
  • a first jet means to jet enriched gas of a smaller mass number of said mixture of gases from the internal axially peripheral region of said rotary chamber into said lower jetting container;
  • a second jet means to jet depleted gas of a smaller mass number of said mixture of gases from the internal axially peripheral region of said rotary chamber into said upper container;
  • a fifth duct feeding means to feed said light gas into said circumferential chamber and from there from the upper and lower regions thereof into said upper and lower containers, respectively;
  • a centrifuge as claimed in claim 1 further comprising a heating device adjacent the upper region of said rotary chamber and a cooling device adjacent the lower region of said rotary chamber.
  • each said end plate provided with an integral shaft axially protruding to the outside of said rotary chamber through a first and fourth orifice, respectively, for rotation through the said housing, and means connected to at least one of said shafts to rotate said rotary chamber.
  • a centrifuge as claimed in claim l the shaft of said upper 5.
  • said first duct means comprising a pressure control valve and a pump means.
  • said first duct means including a pressurized source of a mixture of first gases to be separated and enriched; a pressurized source of a second gas to be admixed to said first gases, a pressurized comixing chamber and a conduit leading from said comixing chamber to said first feeding means.
  • said first jet means comprising orifices spaced in said lower endplate.
  • said second jet means comprising orifices spaced in said upper end-plate.
  • a centrifuge as claimed in claim 1 said second duct means comprising a pressurized valve and a pump means.
  • a centrifuge as claimed in claim ll said third duct means comprising an evacuating pump and pressurized valve means.
  • said fourth duct means comprising a pump and conduits between said shaft of said lower end-plate and said pump.
  • a centrifuge as claimed in claim 1 said circumferential chamber comprising an orifice to the outside, said second duct means comprising a pump and conduits between said orifice and said pump and between said pump and said second duct means.
  • said third jet means comprising means to control the amounts of gases to be drained respectively to the outside of said upper and lower containers to be equal to each other.
  • a centrifuge as claimed in claim 1 said fifth duct including means of flowing the ducted light gas in vector directions parallel to the velocity vectors of said cylindrical surface of said rotary chamber.
  • a centrifuge as claimed in claim 1 further comprising means of providing a thermal gradient within said cylindrical chamber.
  • a centrifuge as claimed in claim 20 wherein said light gas pulled out from the rotor to the outside thereof may be further subjected to purification before it is fed to the outside of the rotor by using another type of centrifuge.
  • said centrifuge including an outer chamber and a rotary chamber situated within said outer chamber and mounted rotatably thereto;
  • said process comprising the steps of feeding the mixture of gases with a light gas into said rotary chamber through one end plate thereof;
  • pressurizing said gas mixture centrifuging said gas mixture into a first (upper) and second (lower) region; heating said gas in said first region; cooling the gas in said second region; jetting said gas from said first region into a depleted gas zone and said gas from said second region into an enriched gas zone; providing an intermediate gas zone; simultaneously centrifuging the gas from said second zone to said intermediate zone, and withdrawing gas from said lower region to said intermediate zone; withdrawing gas from said first zone; and repeating said cycle using the last mentioned step of said withdrawing said gas as the initial step of pressurizing said gas mixture in said subsequent cycle.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Centrifugal Separators (AREA)
US768981A 1967-10-26 1968-10-21 Gas centrifuges, their assembly and a process for enriching uranium 235 Expired - Lifetime US3613989A (en)

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JP42068490A JPS4811278B1 (enrdf_load_stackoverflow) 1967-10-26 1967-10-26

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JP (1) JPS4811278B1 (enrdf_load_stackoverflow)
DE (1) DE1801307A1 (enrdf_load_stackoverflow)
FR (1) FR1589275A (enrdf_load_stackoverflow)
GB (1) GB1212449A (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3774376A (en) * 1970-06-17 1973-11-27 Tokyo Shibaura Electric Co Centrifugal gas separator
US3973929A (en) * 1973-07-12 1976-08-10 Balzers Patent Und Beteiligungs Ag Method and apparatus for enriching a lower molecular weight gas with substances of higher molecular weight contained therein
US4193775A (en) * 1976-07-27 1980-03-18 Wang Chia Gee Methods and apparatus for separating gases with ventilated blades
WO1981001801A1 (en) * 1979-12-19 1981-07-09 C Wang Method and apparatus for separating gases with ventilated blades
US4290781A (en) * 1977-08-15 1981-09-22 Wang Chia Gee Methods and apparatus for separating gases with ventilated blades
US4516966A (en) * 1981-07-21 1985-05-14 British Nuclear Fuels Limited Centrifuges, centrifuge plants and flow control arrangements therefor
US20080300124A1 (en) * 2007-05-31 2008-12-04 Hitachi Koki Co., Ltd. Centrifuge
US20100018392A1 (en) * 2006-05-31 2010-01-28 Swce Supercritical fluid enrichment of isotopes
US20100313751A1 (en) * 2009-02-20 2010-12-16 H R D Corporation Apparatus and method for gas separation
US20220152631A1 (en) * 2019-02-26 2022-05-19 Gea Mechanical Equipment Gmbh Separator

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2936110A (en) * 1945-01-31 1960-05-10 Cohen Karl Method of centrifuge operation
US3191856A (en) * 1962-03-27 1965-06-29 Beckman Instruments Inc Centrifuge rotor
US3289925A (en) * 1957-11-14 1966-12-06 Degussa Centrifugal separators
US3332614A (en) * 1964-10-30 1967-07-25 Donald S Webster Centrifugal extractor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2936110A (en) * 1945-01-31 1960-05-10 Cohen Karl Method of centrifuge operation
US3289925A (en) * 1957-11-14 1966-12-06 Degussa Centrifugal separators
US3191856A (en) * 1962-03-27 1965-06-29 Beckman Instruments Inc Centrifuge rotor
US3332614A (en) * 1964-10-30 1967-07-25 Donald S Webster Centrifugal extractor

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3774376A (en) * 1970-06-17 1973-11-27 Tokyo Shibaura Electric Co Centrifugal gas separator
US3973929A (en) * 1973-07-12 1976-08-10 Balzers Patent Und Beteiligungs Ag Method and apparatus for enriching a lower molecular weight gas with substances of higher molecular weight contained therein
US4193775A (en) * 1976-07-27 1980-03-18 Wang Chia Gee Methods and apparatus for separating gases with ventilated blades
US4290781A (en) * 1977-08-15 1981-09-22 Wang Chia Gee Methods and apparatus for separating gases with ventilated blades
WO1981001801A1 (en) * 1979-12-19 1981-07-09 C Wang Method and apparatus for separating gases with ventilated blades
US4516966A (en) * 1981-07-21 1985-05-14 British Nuclear Fuels Limited Centrifuges, centrifuge plants and flow control arrangements therefor
US8241394B2 (en) * 2006-05-31 2012-08-14 SWCE Inc. Supercritical fluid enrichment of isotopes
US20100018392A1 (en) * 2006-05-31 2010-01-28 Swce Supercritical fluid enrichment of isotopes
US7967893B2 (en) * 2006-05-31 2011-06-28 Swce Supercritical fluid enrichment of isotopes
US20080300124A1 (en) * 2007-05-31 2008-12-04 Hitachi Koki Co., Ltd. Centrifuge
US7874973B2 (en) * 2007-05-31 2011-01-25 Hitachi Koki Co., Ltd. Centrifuge with steam sterilization
US20100313751A1 (en) * 2009-02-20 2010-12-16 H R D Corporation Apparatus and method for gas separation
US8277540B2 (en) * 2009-02-20 2012-10-02 H R D Corporation Apparatus and method for gas separation
US20130133514A1 (en) * 2009-02-20 2013-05-30 H R D Corporation Apparatus and method for gas separation
US8734566B2 (en) * 2009-02-20 2014-05-27 H R D Corporation Apparatus and method for gas separation
US9108148B2 (en) 2009-02-20 2015-08-18 H R D Corporation Apparatus and method for gas separation
US20220152631A1 (en) * 2019-02-26 2022-05-19 Gea Mechanical Equipment Gmbh Separator
US12303918B2 (en) * 2019-02-26 2025-05-20 Gea Mechanical Equipment Gmbh Separator for separating a flowable suspension into two flowable phases of different density
US12311388B2 (en) 2019-02-26 2025-05-27 Gea Mechanical Equipment Gmbh Magnetically suspended and rotated separator

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Publication number Publication date
GB1212449A (en) 1970-11-18
FR1589275A (enrdf_load_stackoverflow) 1970-03-23
DE1801307A1 (de) 1970-04-23
JPS4811278B1 (enrdf_load_stackoverflow) 1973-04-12

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