CA1081436A - Remote nuclear green pellet processing system - Google Patents
Remote nuclear green pellet processing systemInfo
- Publication number
- CA1081436A CA1081436A CA295,976A CA295976A CA1081436A CA 1081436 A CA1081436 A CA 1081436A CA 295976 A CA295976 A CA 295976A CA 1081436 A CA1081436 A CA 1081436A
- Authority
- CA
- Canada
- Prior art keywords
- access area
- disposed
- restricted access
- feed hopper
- components
- 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.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
- G21C3/42—Selection of substances for use as reactor fuel
- G21C3/58—Solid reactor fuel Pellets made of fissile material
- G21C3/62—Ceramic fuel
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Solid Fuels And Fuel-Associated Substances (AREA)
- Glanulating (AREA)
- Monitoring And Testing Of Nuclear Reactors (AREA)
Abstract
REMOTE NUCLEAR GREEN FELLET PROCESSING SYSTEM
ABSTRACT OF THE DISCLOSURE
An automated system for manufacturing nuclear fuel pellets for use in nuclear fuel elements of nuclear power reactors. The system comprises process components arranged vertically but not directly under each other within a single enclosure. The vertical-lateral arrangement provides for gravity flow of the product from one component to the next and for vertical removal of each component without inter-ference with the other components. The single enclosure eliminates time consuming transfer between separate en-closures of each component while providing three-sided access to the component through glove ports.
ABSTRACT OF THE DISCLOSURE
An automated system for manufacturing nuclear fuel pellets for use in nuclear fuel elements of nuclear power reactors. The system comprises process components arranged vertically but not directly under each other within a single enclosure. The vertical-lateral arrangement provides for gravity flow of the product from one component to the next and for vertical removal of each component without inter-ference with the other components. The single enclosure eliminates time consuming transfer between separate en-closures of each component while providing three-sided access to the component through glove ports.
Description
BACKGROUND OF THE INVENTION
This invention relates to systems for manu~act-uring nuclear fuel green pellets and particularly to such systems wherein the process is automated.
In many designs of nuclear reactors, the reactor vessel has an inlet and outlet for circulation of a coolant in-heat transfer relationship with a core contained therein that produces heat. The core comprises~an array or-arrays of fuel assemblies which contain fuel elements. The fuel element is generally a cylindrical metallic sheath sealed a' -- both ends containing nuclear fuel. The nuclear fuel which may be, for example, ceramic fuel pellets of a uranium com-pound, is stacked within the metallic sheath. During reacto~
operation, the nuclear fuel pellets decompose releasing fission products such as fission gas while generating heat in a manner well known in the art.
.
, , - : . :. .
~ 46,5~1 1081~36 There are many known methods for manufacturing the nuclear fuel pellets used in nuclear reactors. Most of these methods generally consist of cold pressing a powder which may be an oxide of fissionable material such as uranium dioxide to form dense compacts. These dense com-pacts are ~enerally referred to as green pellets. The green pellets are then sintered in a non-oxidi~ing atmosphere to produce a sintered pellet which may have slight irregulari-ties on its surface. The sintered pellet may then be ground to remove those irregularities thereby forming a right cylindrical pellet. This finished pellet is then stacked within the metallic sheath to form the fuel element that may be used in a nuclear reactor.
A commonly known method for producing the nuclear fuel pellets is described in U.S. Patent No. 2,991,601 to J.
Glatter et all issued July 11, 1961. In this process, ~; hydrogen reduction of uranium trioxide is employed to produce uranium dioxide powder. As received from commercial manufacturers, this uranium dioxide is not free flowing and ~,-is, therefore, not adaptable for use in automatic machinery for the production of the green pellets. In order to produce a free flowing powder, the uranium dioxide powder is mlxed - with a suitable binder such as aluminum stearate and water . ~-~ to form a wet granulate. The wet granulate is then forced .
-~ through a screen and dried, after which it is dry-screened '~6~' thereby separating the larger particles from the smaller particles. The water may be substantially removed in the later sintering process while the aluminum stearate wiIl re-main and act as a lubricant in the compacting process. Once the uranium dioxide powder has thus been converted into a .. . . . . .
~ 46,581 :~081436 free flowing granulate, the granulate is then compacted in~o green pellets in a cold pressing operation. The compactin~
process comprises flowing the granulate into a die and cold pressing the granulate in the die into substantially cylin-drical green pellets. The green pellets may then be heat treated, sinteræd and ground to form the finished pellet for use in nuclear fuel elemellts.
While the patent to ~-latter and other known methods lllustrate conlmonly understood metllods of manufacturing 10 green pellets, these methods all involve relatively small -volume production. Because the prior art methods involved small volume production, these processes were performed in a . .
glove box environment. Each process was performed in a separate glove box type enclosure and then moved under secure conditions to the next glove box where the succeeding step was performed. This glove box arrangement not only required long time intervals during bag-out transfer between glove boxes, but it also required a large amount of floor space to accommodate the glove boxes. Furthermore, the glove box enclosure did not provide adequate accessibility to the~apparatus therein due to the limlted oapability of the typical glove box arrangements. With the demand for nuclear fuel increasing it became a commercial necessity to be able to mass produce the green pellets. Such mass pro-duction would entaIl larger apparatus and faster throughput both of which were not compatible with conventional glove box arrangements. In addition, the recent use of plutonium dloxide in a mixed oxide pellet increased the safeguards which must be employed to assure accountability of the plu-tonium. The necessity of moving the plutonium from one --3-- ~
: . .. . . ,: - ~ , , -- ,-- 46,581 ~ 108~436 --.
glove box to the next in a large volume process would crea~
serious accountability problems that result in substantial time delays during such transfer between glove boxes. All of these problems together render impractical a large volul~-production of a mixed oxide green pellet in a typical glo~e box arrangement.
;SUMMARY OF THE INV~NTION
~ An automated system for manufacturing nuclear fue .
green pellets for use in nuclear fuel elements of nuclear power reactors. The system comprises process components for manufacturing nuclear fuel green pellets arranged in verti-cal succession with each component displaced laterally with J ' ~
- respect to the other components. The vertical arrangement provides for gravity f~ow of the products from one component to the next while the lateral placement allows for unob-structed overhead access to each component so that each - component may be vertically removed without interference ~ -from the other components. The components are eontained ; wlthin a single enclosure that provides access to three 20~ sides of each component for maintenance and operation.
It is an ob~ect of this invention to prov~de an automated sy~tem for manufacturing nuclear fuel green pel-,; . ~ ~ .
- ; lets in which the components are arranged vertlcally so that the products Or the process may flow from one component to the next by the force of gravity.
It is another obJect of this inventlon to provide an automated system for manufacturing nuclear fuel green . .
pellets ln which the components are arranged to allow un-obætructed vertical access to each component.
` 30 It is another ob~ect of this inventlon to provide -`~ ~4~
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. . . ... . .... . . .
.. , .. - . . .. -. : .. - . . : ... - . ....... . -~`
46,581 108~436 an autonlated system for manufacturing nuclear green pellets in which the components are arranged within a single enc-losure that allows for access to each component from at least three sides.
It is a particular ob~ject of this invention to provide an autolll3ted syste!n for manufacturing nuclear fuel ~r~en pellet~ in which the components are arran~ed within a single enclosure to provide unobstructed vertical access to each component, gravity flow between components, and access to each component from at least three sides.
- - BRIEF DESCRIPTION_~F THE DRAWINGS
While the specification concludes wlth claims specifically pointing out and distinctly claiming the subject matter of the invention, it is believed the in-vention will be better understood from the following des-crlption taken in con~unction with the accompanying drawings, wherein:
~ . . .
Figure 1 is a partial cross-sectional view in ele-vation of the enclosure;
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20~ Figure 2 is a plan view of Figure l;
Figure 3 1s a partial cross-sectional.view in ele-vation of the enclosure lncluding apparatus; and Flgure 4 is a view alon~ llne IV-IV of Figure 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the commonly known processes used to manufac-~ .
~ .' ture nuclear fuel pellets, the individual subprocesses are ... ~ . .
performed in separate glove box enclosures. Upon completion of-each subprocess, the material is carefully moved to the neXt glove box enclosure. The invention described hereln provides method and apparatus for manufacturing nuclear fuel ~5~
' . .
~- ~081436 46,581 ~ green pellets in an automated fashion capable of large : volume production.
Referring to Figure 1, a horizontal first floor 10 .
is supported by a vertical first wall 12. First wall 12 is supported from second floor 14 with first floor 10, first wall 12, and a portion of second floor 14 definin~ a first chamber 16. A second wall 18 extends from second floor 14 down to third floor 20. A first partitioll 22, second parti-tion 24, third pqrtitiorl '6, fourth yartition 28, and fifth 10 partition 30 together with second wall l8 and second floor :`
: 14 define second chamber 32 and third chamber 34. A third .
wall 36 extends downwardly from third floor 20 and encloses fourth chamber 38. A fourth wall 40 that is parallel to second wall 18 and third wall 36 extends from second floor 14 to fourth floor 42. The entire structure defined above is contained within a single bullding the inner walls of : which along with first wall 12 and second floor 14 define a .
: . first area 44. A second area 46 is defined below fir-st area 44 by second wall l8, third floor 20, and fourth wall 40.
In:addition, a third area 48 is defined below second area 46 by~fourth wall 40 and third wall 36. A tunnel 50 which is : used for maintenance access ls supported through second area 46 and third area 48 while a sixth partition ~2 defines a fifth chamber 54 thereunder.
Referring now to Figùre 4? first area 44 is fur-ther defined by a fifth wall 56 which is perpendicular to :flrst wall 12. .Similarly, second area 46 ls bounded on two .~ sides by sixth wall 58 and seventh wall 60 which are per-pendicular to second wall 18. Likewise, eighth wall 62 and ninth wall 64 further define third area 48. Flrst area 44, -.
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-.. . . : . . : .: . . .
' ' ', ' . : ., . ~ . '. '. . ,, , ' ., -:
~ A 46,581 lQ~L436 second area 46, and thiId area 48 together with their sur-rounding structure establish areas such that fuel processing equipment may be vertically arranged therein. The vertical arrangement allows for gravity flow of the material from one subprocess to another. This arrangement also allows for vertical access to the equipment along with side access from behind radiatioll protective walls.
Referring now to Figures 3 and 4, a compactor feed hopper G6 is disposed in first area 44 near flrst wall 12.
A selected mixture of plutonium dioxide (Pu02) and uranium dioxide (U02) known as mixed oxide fuel powder is introduced into compactor feed hopper 66 through pneumatic line 68.
Compactor feed hopper 66 which is used to store the mixed oxide powder has level sensors (not shown) that indicate the level of the mixed oxide powder in the hopper. A star feeder 70 is connected between compactor feed hopper 66 and .
roll compactor 72 so as to control the flow rate of mixed oxide powder from compactor feed hopper 66 to roll compactor ~ 72. Roll compactor 72 is located on second floor 14 at an P~ ~ 20 elevation lower than star feeder 70 which allows the mixed ox1de powder to flow into roll compactor 72 under the influ-ence of gravity. Star feeder 70 has a first drive meohanism 74 and roll compactor 72 has a second drive mechanism 76 that are both located in first chamber 16 behind first wall 12. ~he driving arm of both drive mechanisms e~tend through sealing mechanisms in first wall 12 to their respective machinery. Because the mixed oxide powder in the apparatus such as compactor feed hopper 66 and roll compactor 72 may produce radiation levels that are unacceptable for a long-term working environment, first wall 12 is constructed by if~':' ~ `
1-' ' :' ' , ~ ~ 46,581 ~01 31436 common methods so as to limit such radiation in first chamber 16. First wall 12, therefore, allows working personnel to operate and repair the apparatus in first chamber 16 such as drive mechanisms 74 and 76 without exposing such personnel to excessive radiation. In addition, the location of such equipmellt behind a shielding wall decreases repair time because such equipl1lent is not contaltlinated. In ~ddition, glove holes are providæd at various locations alon~ the walls so that a~cess may be had to the equipment in the enclosures. For example, glove holes are provided at loca-tions referred to generally by 78. It should be noted that the equipment is placed near the walls such as 12 and 56 so that access may be had to the equipment when necessary. As shown in Figure 4, a person standing on second floor 14 could reach through glove holes 78 to reach star feeder 70 . ~
or roll compactor 72. Should this apparatus malfunction, mlnor repalrs could be made in this manner or the non-unct1aning equipment could be disconnected by hand and then removed by mechanical apparatus such as a crane 80.
ZO~ Roll~compactor 72 comprises two opposing drums that~rolls the powde~r into ribbon-like strips of various leneths. These ribbon-like strlps fall by gravity into a granulator 82 that granulates the strips into fine particles.
Granulator 82 is disposed in second area 46 and below roll compactor 72 so that gravity may be employed to move the ribbon-like strips. However, granulator 82 is not located directIy under roll compactor 72, rather it is located laterally from roll compactor 72 as shown in Figure 3.
Granulator 82 is not located directly below roll compactor 72 80 that should it need to be replaced it could be dis-~ -8-: ;~ ,~ :
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46,581 connected by iland throu~h ~,love holes 78 and then be lifted upwardly onto first floor 10 without having to remove roll compactor 72. This arrangement provides for an automated gravity flow without havlng the various components interfere with each other during insertion or removal of a particular component. As with roll compactor 72, granulator 82 has a granulator drive mechanism 84 located in second chamber 32 behind second wall 18.
A cl~ssifier 86 is located below granulator 82 in second area 46. Classifier 86 consists of three chambers arranged vertically within a single housing with two vibrat-ing screens separating the three chambers. Granules from granulator 82 flow by gravity into the first chamber and onto the first screen of classifier 86. Oversized granules are caught on the first vibrating screen and carrled off by the vibrating actlon into a scrap transfer can 88. The remaining granules fall through the first screen onto the second vibrating screen. The proper size granules are ~ ~ carried by the second vibrating screen to a bulk density `~ 20 check station 89 that monitors the density of the granules. -~- Granules having the proper density are permitted to flow to rolling drum 90. The smaller granules fall through both the first and second screens into the bottom of the classifer 86 -~ from where they are pneumatically transferred through re-~ cycle line 92 back into compactor feed hopper 66.
-~ Rolling drum 90 is located on third floor 20 and disposed laterally from classifier 86 so that the proper size granules may flow from the second vibrating screen to rolling drum 90 under the influence of gravity while being able to be lifted vertically by crane 80 without interfering _9_ ~ .
.. . .. . .. . . . . .. . . .. . .. .... ... . . . . . .
~081436 46,5~1 onents. As is well underst~od in the art, the granules that are formed as previously described do not readily compact.
In order to promote compaction of the granules into pellets a lubricant is added. A typical lubricant so used is aluminum stearate. A stearate feed hopper 94 is disposed on fifth wall 56 with a stearate line 96 attached to the under-side thereof. Stearate line 96 is also attached to the top portion of ste~late feeder 98 so that the stearate may flow from stearate feed hoppeI 94 through stearate line 96 into - 10 stearate feeder 98 under the force of gravity. Stearate feeder 98 serves to accumulate stearate therein to insure a constant flow to rolling drwn 90. Rolling drum 90 is a drum which mechanically rotates about its longitudinal axis to , ~ . .
thereby mix the granules with the stearate. As with the other components in the system, the stearate feeder 98 is lntended to be located near the enclosing walls such as sevénth wall 60 so that maintenance and operational access may be had through glove holes 78. Furthermore, stearate feeder 98 is located so that gravity flow may be utilized 20~ while crane 80 may be employed to manipuIate the component.
; From rolling drum gO, the mixture of stearate and granules flows by gravity into pellet press feed hopper 100.
,: ~
Pellet press feed hopper 100 is disposed below rolling drum 90 to facilitate gravity flow but not directly thereunder so as to facilitate removal by crane 80. From pellet press feed hopper 100, the mixture flows through dual powder lines 102 into pellet press 104. Pellet press 104 consists of an , upper punch 106, lower punch 108, and die 110 as is commonly known in the art. Pellet press 104 is disposed in third area 48 so that gravity may be utilized to flow the mixture :
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from pellet press feed hopper 100 to pellet press 104.
Upper punch 106 is mounted in tunnel 50 and ex-tends downwardly through a sealing mechanism into third area 48. Similarly, lower punch 108 is mounted in sixth chamber 54 and extends upwardly into opposition with upper punch 106. The arr~n~,elnent of u~per pullch 106 in tunnel 50 and lower punch 10~ in sixth chamber 54 provides for an auto-mated operation while allowing access to the machinery from an enclosure to avoid exposure to radlation. For example, repairs may be made to upper punch 106 from within tunnel 50 without exposing the personnel to radiation. Furthermore, since tunnel 50 extends through second area 46 and third area 48, personnel in tunnel 50 nlay access other equipment through glove holes 78, When one of the dual powder lines 102 is altern-ately placed over die 110, a predetermined amount of the mixture in pellet press feed hopper 100 is allowed to flow into dle 110. Upper punch 106 and lower punch 108 are then advanced into opposite ends of die 110 which compresses the mlxture into nuclear fuel pellets conforming to the shape of dle 110. Such pellets are referred to as green pellets.
The punches are then withdrawn and pellet loader 112 or dual powder lines 102 pushes the green pellet onto conveyor 114 which moves the green pellet to the next operation which may ~ ~ be a sintering operatlon.
-`~ As can be seen from the foregoing descriptlon, first area 44, second area 46 and third area 48 define a restricted access area that is exposed to radiation and other contaminants. Because of the nature of the radiation and contamination due primarily to plutonium in the re-.
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1081436 4~,581 stricted access area, it is recommended that personnel not be present therein for extended lengths of time. It is, therefore, recommended that the working personnel remain behind radiation protection such as first wall 12, second wall 18, ~ilird wall 36, and fourth wall 40. The areas - behind such protective walls including but not limited to first chamber 1~, second chamber 32 and third chamber 34 define a limited access area wherein working personnel may be present for controlled periods of time. As described above, parts of the equipment extend through the protective walls into the limited access area so that personnel may have access to them without being unnecessarily exposed to radiation. The gloves holes 70 provide access from the limited access area to the restricted access area while a higher pressure is maintained in the limited access area so that the flow of air and particles will be into the re-strlcted access area thereby preventing outward flow. The equipment in the restricted access area is, therefore, arranged close to at least one of three protective walls so as to increase this access. In addition, to this three-sided accessibility the equipment is arranged vertically but not directly under each other so that removal and replace-ment of the equipment may be facilitated by means such as crane 80 without interfering with the remaining equipment.
Moreover, the vertical arrangement provides for gravity flow .~
of the products while minimizing the required floor space.
The gravity flow feature is particularly important because it provides for rapid product throughput with minimal hold-up periods and allows for efficient material clean-out, more commonly known as run-out. Efficient material run-out ' 108~436 46,581 assures that no material remains in the components after each batch is completed. The importance of this liesin the fact that strict accountability of the plutonium is necessitated by governmental and industry standards and that a previous batch will not contaminate a subsequent batch wlth a diffeIetlt materi~l composition. The invention, therefore, provides an autolllated system for manufacturing nuclear fuel gleen pellets withill ~ sin~le enclosure to provide unobstructed vertical access to each cQmponent, ~r~vity flow between components, and access to each compo-nent from at least three sides. `
While there is described what is now considered to be the preferred embodiment of the invention, it is, of course, understood that various other modifications and varlations will occur to those skilled in the art. The clalms, therefore are intended to include all such modi-~; fications and variations which fall within the true spirit and scope of the present invention.
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This invention relates to systems for manu~act-uring nuclear fuel green pellets and particularly to such systems wherein the process is automated.
In many designs of nuclear reactors, the reactor vessel has an inlet and outlet for circulation of a coolant in-heat transfer relationship with a core contained therein that produces heat. The core comprises~an array or-arrays of fuel assemblies which contain fuel elements. The fuel element is generally a cylindrical metallic sheath sealed a' -- both ends containing nuclear fuel. The nuclear fuel which may be, for example, ceramic fuel pellets of a uranium com-pound, is stacked within the metallic sheath. During reacto~
operation, the nuclear fuel pellets decompose releasing fission products such as fission gas while generating heat in a manner well known in the art.
.
, , - : . :. .
~ 46,5~1 1081~36 There are many known methods for manufacturing the nuclear fuel pellets used in nuclear reactors. Most of these methods generally consist of cold pressing a powder which may be an oxide of fissionable material such as uranium dioxide to form dense compacts. These dense com-pacts are ~enerally referred to as green pellets. The green pellets are then sintered in a non-oxidi~ing atmosphere to produce a sintered pellet which may have slight irregulari-ties on its surface. The sintered pellet may then be ground to remove those irregularities thereby forming a right cylindrical pellet. This finished pellet is then stacked within the metallic sheath to form the fuel element that may be used in a nuclear reactor.
A commonly known method for producing the nuclear fuel pellets is described in U.S. Patent No. 2,991,601 to J.
Glatter et all issued July 11, 1961. In this process, ~; hydrogen reduction of uranium trioxide is employed to produce uranium dioxide powder. As received from commercial manufacturers, this uranium dioxide is not free flowing and ~,-is, therefore, not adaptable for use in automatic machinery for the production of the green pellets. In order to produce a free flowing powder, the uranium dioxide powder is mlxed - with a suitable binder such as aluminum stearate and water . ~-~ to form a wet granulate. The wet granulate is then forced .
-~ through a screen and dried, after which it is dry-screened '~6~' thereby separating the larger particles from the smaller particles. The water may be substantially removed in the later sintering process while the aluminum stearate wiIl re-main and act as a lubricant in the compacting process. Once the uranium dioxide powder has thus been converted into a .. . . . . .
~ 46,581 :~081436 free flowing granulate, the granulate is then compacted in~o green pellets in a cold pressing operation. The compactin~
process comprises flowing the granulate into a die and cold pressing the granulate in the die into substantially cylin-drical green pellets. The green pellets may then be heat treated, sinteræd and ground to form the finished pellet for use in nuclear fuel elemellts.
While the patent to ~-latter and other known methods lllustrate conlmonly understood metllods of manufacturing 10 green pellets, these methods all involve relatively small -volume production. Because the prior art methods involved small volume production, these processes were performed in a . .
glove box environment. Each process was performed in a separate glove box type enclosure and then moved under secure conditions to the next glove box where the succeeding step was performed. This glove box arrangement not only required long time intervals during bag-out transfer between glove boxes, but it also required a large amount of floor space to accommodate the glove boxes. Furthermore, the glove box enclosure did not provide adequate accessibility to the~apparatus therein due to the limlted oapability of the typical glove box arrangements. With the demand for nuclear fuel increasing it became a commercial necessity to be able to mass produce the green pellets. Such mass pro-duction would entaIl larger apparatus and faster throughput both of which were not compatible with conventional glove box arrangements. In addition, the recent use of plutonium dloxide in a mixed oxide pellet increased the safeguards which must be employed to assure accountability of the plu-tonium. The necessity of moving the plutonium from one --3-- ~
: . .. . . ,: - ~ , , -- ,-- 46,581 ~ 108~436 --.
glove box to the next in a large volume process would crea~
serious accountability problems that result in substantial time delays during such transfer between glove boxes. All of these problems together render impractical a large volul~-production of a mixed oxide green pellet in a typical glo~e box arrangement.
;SUMMARY OF THE INV~NTION
~ An automated system for manufacturing nuclear fue .
green pellets for use in nuclear fuel elements of nuclear power reactors. The system comprises process components for manufacturing nuclear fuel green pellets arranged in verti-cal succession with each component displaced laterally with J ' ~
- respect to the other components. The vertical arrangement provides for gravity f~ow of the products from one component to the next while the lateral placement allows for unob-structed overhead access to each component so that each - component may be vertically removed without interference ~ -from the other components. The components are eontained ; wlthin a single enclosure that provides access to three 20~ sides of each component for maintenance and operation.
It is an ob~ect of this invention to prov~de an automated sy~tem for manufacturing nuclear fuel green pel-,; . ~ ~ .
- ; lets in which the components are arranged vertlcally so that the products Or the process may flow from one component to the next by the force of gravity.
It is another obJect of this inventlon to provide an automated system for manufacturing nuclear fuel green . .
pellets ln which the components are arranged to allow un-obætructed vertical access to each component.
` 30 It is another ob~ect of this inventlon to provide -`~ ~4~
. . .
. . . ... . .... . . .
.. , .. - . . .. -. : .. - . . : ... - . ....... . -~`
46,581 108~436 an autonlated system for manufacturing nuclear green pellets in which the components are arranged within a single enc-losure that allows for access to each component from at least three sides.
It is a particular ob~ject of this invention to provide an autolll3ted syste!n for manufacturing nuclear fuel ~r~en pellet~ in which the components are arran~ed within a single enclosure to provide unobstructed vertical access to each component, gravity flow between components, and access to each component from at least three sides.
- - BRIEF DESCRIPTION_~F THE DRAWINGS
While the specification concludes wlth claims specifically pointing out and distinctly claiming the subject matter of the invention, it is believed the in-vention will be better understood from the following des-crlption taken in con~unction with the accompanying drawings, wherein:
~ . . .
Figure 1 is a partial cross-sectional view in ele-vation of the enclosure;
,, s i: ~
20~ Figure 2 is a plan view of Figure l;
Figure 3 1s a partial cross-sectional.view in ele-vation of the enclosure lncluding apparatus; and Flgure 4 is a view alon~ llne IV-IV of Figure 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the commonly known processes used to manufac-~ .
~ .' ture nuclear fuel pellets, the individual subprocesses are ... ~ . .
performed in separate glove box enclosures. Upon completion of-each subprocess, the material is carefully moved to the neXt glove box enclosure. The invention described hereln provides method and apparatus for manufacturing nuclear fuel ~5~
' . .
~- ~081436 46,581 ~ green pellets in an automated fashion capable of large : volume production.
Referring to Figure 1, a horizontal first floor 10 .
is supported by a vertical first wall 12. First wall 12 is supported from second floor 14 with first floor 10, first wall 12, and a portion of second floor 14 definin~ a first chamber 16. A second wall 18 extends from second floor 14 down to third floor 20. A first partitioll 22, second parti-tion 24, third pqrtitiorl '6, fourth yartition 28, and fifth 10 partition 30 together with second wall l8 and second floor :`
: 14 define second chamber 32 and third chamber 34. A third .
wall 36 extends downwardly from third floor 20 and encloses fourth chamber 38. A fourth wall 40 that is parallel to second wall 18 and third wall 36 extends from second floor 14 to fourth floor 42. The entire structure defined above is contained within a single bullding the inner walls of : which along with first wall 12 and second floor 14 define a .
: . first area 44. A second area 46 is defined below fir-st area 44 by second wall l8, third floor 20, and fourth wall 40.
In:addition, a third area 48 is defined below second area 46 by~fourth wall 40 and third wall 36. A tunnel 50 which is : used for maintenance access ls supported through second area 46 and third area 48 while a sixth partition ~2 defines a fifth chamber 54 thereunder.
Referring now to Figùre 4? first area 44 is fur-ther defined by a fifth wall 56 which is perpendicular to :flrst wall 12. .Similarly, second area 46 ls bounded on two .~ sides by sixth wall 58 and seventh wall 60 which are per-pendicular to second wall 18. Likewise, eighth wall 62 and ninth wall 64 further define third area 48. Flrst area 44, -.
'. :
-.. . . : . . : .: . . .
' ' ', ' . : ., . ~ . '. '. . ,, , ' ., -:
~ A 46,581 lQ~L436 second area 46, and thiId area 48 together with their sur-rounding structure establish areas such that fuel processing equipment may be vertically arranged therein. The vertical arrangement allows for gravity flow of the material from one subprocess to another. This arrangement also allows for vertical access to the equipment along with side access from behind radiatioll protective walls.
Referring now to Figures 3 and 4, a compactor feed hopper G6 is disposed in first area 44 near flrst wall 12.
A selected mixture of plutonium dioxide (Pu02) and uranium dioxide (U02) known as mixed oxide fuel powder is introduced into compactor feed hopper 66 through pneumatic line 68.
Compactor feed hopper 66 which is used to store the mixed oxide powder has level sensors (not shown) that indicate the level of the mixed oxide powder in the hopper. A star feeder 70 is connected between compactor feed hopper 66 and .
roll compactor 72 so as to control the flow rate of mixed oxide powder from compactor feed hopper 66 to roll compactor ~ 72. Roll compactor 72 is located on second floor 14 at an P~ ~ 20 elevation lower than star feeder 70 which allows the mixed ox1de powder to flow into roll compactor 72 under the influ-ence of gravity. Star feeder 70 has a first drive meohanism 74 and roll compactor 72 has a second drive mechanism 76 that are both located in first chamber 16 behind first wall 12. ~he driving arm of both drive mechanisms e~tend through sealing mechanisms in first wall 12 to their respective machinery. Because the mixed oxide powder in the apparatus such as compactor feed hopper 66 and roll compactor 72 may produce radiation levels that are unacceptable for a long-term working environment, first wall 12 is constructed by if~':' ~ `
1-' ' :' ' , ~ ~ 46,581 ~01 31436 common methods so as to limit such radiation in first chamber 16. First wall 12, therefore, allows working personnel to operate and repair the apparatus in first chamber 16 such as drive mechanisms 74 and 76 without exposing such personnel to excessive radiation. In addition, the location of such equipmellt behind a shielding wall decreases repair time because such equipl1lent is not contaltlinated. In ~ddition, glove holes are providæd at various locations alon~ the walls so that a~cess may be had to the equipment in the enclosures. For example, glove holes are provided at loca-tions referred to generally by 78. It should be noted that the equipment is placed near the walls such as 12 and 56 so that access may be had to the equipment when necessary. As shown in Figure 4, a person standing on second floor 14 could reach through glove holes 78 to reach star feeder 70 . ~
or roll compactor 72. Should this apparatus malfunction, mlnor repalrs could be made in this manner or the non-unct1aning equipment could be disconnected by hand and then removed by mechanical apparatus such as a crane 80.
ZO~ Roll~compactor 72 comprises two opposing drums that~rolls the powde~r into ribbon-like strips of various leneths. These ribbon-like strlps fall by gravity into a granulator 82 that granulates the strips into fine particles.
Granulator 82 is disposed in second area 46 and below roll compactor 72 so that gravity may be employed to move the ribbon-like strips. However, granulator 82 is not located directIy under roll compactor 72, rather it is located laterally from roll compactor 72 as shown in Figure 3.
Granulator 82 is not located directly below roll compactor 72 80 that should it need to be replaced it could be dis-~ -8-: ;~ ,~ :
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46,581 connected by iland throu~h ~,love holes 78 and then be lifted upwardly onto first floor 10 without having to remove roll compactor 72. This arrangement provides for an automated gravity flow without havlng the various components interfere with each other during insertion or removal of a particular component. As with roll compactor 72, granulator 82 has a granulator drive mechanism 84 located in second chamber 32 behind second wall 18.
A cl~ssifier 86 is located below granulator 82 in second area 46. Classifier 86 consists of three chambers arranged vertically within a single housing with two vibrat-ing screens separating the three chambers. Granules from granulator 82 flow by gravity into the first chamber and onto the first screen of classifier 86. Oversized granules are caught on the first vibrating screen and carrled off by the vibrating actlon into a scrap transfer can 88. The remaining granules fall through the first screen onto the second vibrating screen. The proper size granules are ~ ~ carried by the second vibrating screen to a bulk density `~ 20 check station 89 that monitors the density of the granules. -~- Granules having the proper density are permitted to flow to rolling drum 90. The smaller granules fall through both the first and second screens into the bottom of the classifer 86 -~ from where they are pneumatically transferred through re-~ cycle line 92 back into compactor feed hopper 66.
-~ Rolling drum 90 is located on third floor 20 and disposed laterally from classifier 86 so that the proper size granules may flow from the second vibrating screen to rolling drum 90 under the influence of gravity while being able to be lifted vertically by crane 80 without interfering _9_ ~ .
.. . .. . .. . . . . .. . . .. . .. .... ... . . . . . .
~081436 46,5~1 onents. As is well underst~od in the art, the granules that are formed as previously described do not readily compact.
In order to promote compaction of the granules into pellets a lubricant is added. A typical lubricant so used is aluminum stearate. A stearate feed hopper 94 is disposed on fifth wall 56 with a stearate line 96 attached to the under-side thereof. Stearate line 96 is also attached to the top portion of ste~late feeder 98 so that the stearate may flow from stearate feed hoppeI 94 through stearate line 96 into - 10 stearate feeder 98 under the force of gravity. Stearate feeder 98 serves to accumulate stearate therein to insure a constant flow to rolling drwn 90. Rolling drum 90 is a drum which mechanically rotates about its longitudinal axis to , ~ . .
thereby mix the granules with the stearate. As with the other components in the system, the stearate feeder 98 is lntended to be located near the enclosing walls such as sevénth wall 60 so that maintenance and operational access may be had through glove holes 78. Furthermore, stearate feeder 98 is located so that gravity flow may be utilized 20~ while crane 80 may be employed to manipuIate the component.
; From rolling drum gO, the mixture of stearate and granules flows by gravity into pellet press feed hopper 100.
,: ~
Pellet press feed hopper 100 is disposed below rolling drum 90 to facilitate gravity flow but not directly thereunder so as to facilitate removal by crane 80. From pellet press feed hopper 100, the mixture flows through dual powder lines 102 into pellet press 104. Pellet press 104 consists of an , upper punch 106, lower punch 108, and die 110 as is commonly known in the art. Pellet press 104 is disposed in third area 48 so that gravity may be utilized to flow the mixture :
-, . . : : :
: ` . ~ '', ~ . `
@,.,`~
from pellet press feed hopper 100 to pellet press 104.
Upper punch 106 is mounted in tunnel 50 and ex-tends downwardly through a sealing mechanism into third area 48. Similarly, lower punch 108 is mounted in sixth chamber 54 and extends upwardly into opposition with upper punch 106. The arr~n~,elnent of u~per pullch 106 in tunnel 50 and lower punch 10~ in sixth chamber 54 provides for an auto-mated operation while allowing access to the machinery from an enclosure to avoid exposure to radlation. For example, repairs may be made to upper punch 106 from within tunnel 50 without exposing the personnel to radiation. Furthermore, since tunnel 50 extends through second area 46 and third area 48, personnel in tunnel 50 nlay access other equipment through glove holes 78, When one of the dual powder lines 102 is altern-ately placed over die 110, a predetermined amount of the mixture in pellet press feed hopper 100 is allowed to flow into dle 110. Upper punch 106 and lower punch 108 are then advanced into opposite ends of die 110 which compresses the mlxture into nuclear fuel pellets conforming to the shape of dle 110. Such pellets are referred to as green pellets.
The punches are then withdrawn and pellet loader 112 or dual powder lines 102 pushes the green pellet onto conveyor 114 which moves the green pellet to the next operation which may ~ ~ be a sintering operatlon.
-`~ As can be seen from the foregoing descriptlon, first area 44, second area 46 and third area 48 define a restricted access area that is exposed to radiation and other contaminants. Because of the nature of the radiation and contamination due primarily to plutonium in the re-.
: . , . ,, ~ ..
... - :, :
~ ' . : ~ .' ' ' . ' ' ' ;., '. . ' ;
.
. .
.
~ \ ~
1081436 4~,581 stricted access area, it is recommended that personnel not be present therein for extended lengths of time. It is, therefore, recommended that the working personnel remain behind radiation protection such as first wall 12, second wall 18, ~ilird wall 36, and fourth wall 40. The areas - behind such protective walls including but not limited to first chamber 1~, second chamber 32 and third chamber 34 define a limited access area wherein working personnel may be present for controlled periods of time. As described above, parts of the equipment extend through the protective walls into the limited access area so that personnel may have access to them without being unnecessarily exposed to radiation. The gloves holes 70 provide access from the limited access area to the restricted access area while a higher pressure is maintained in the limited access area so that the flow of air and particles will be into the re-strlcted access area thereby preventing outward flow. The equipment in the restricted access area is, therefore, arranged close to at least one of three protective walls so as to increase this access. In addition, to this three-sided accessibility the equipment is arranged vertically but not directly under each other so that removal and replace-ment of the equipment may be facilitated by means such as crane 80 without interfering with the remaining equipment.
Moreover, the vertical arrangement provides for gravity flow .~
of the products while minimizing the required floor space.
The gravity flow feature is particularly important because it provides for rapid product throughput with minimal hold-up periods and allows for efficient material clean-out, more commonly known as run-out. Efficient material run-out ' 108~436 46,581 assures that no material remains in the components after each batch is completed. The importance of this liesin the fact that strict accountability of the plutonium is necessitated by governmental and industry standards and that a previous batch will not contaminate a subsequent batch wlth a diffeIetlt materi~l composition. The invention, therefore, provides an autolllated system for manufacturing nuclear fuel gleen pellets withill ~ sin~le enclosure to provide unobstructed vertical access to each cQmponent, ~r~vity flow between components, and access to each compo-nent from at least three sides. `
While there is described what is now considered to be the preferred embodiment of the invention, it is, of course, understood that various other modifications and varlations will occur to those skilled in the art. The clalms, therefore are intended to include all such modi-~; fications and variations which fall within the true spirit and scope of the present invention.
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i :
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Claims (2)
1. A system for manufacturing nuclear fuel pellets comprising:
a restricted access area defined by a plurality of radiation protective vertical walls and horizontal floors offset from each other which contain components for manu-facturing nuclear fuel pellets;
a limited access area defined by said protective walls and floors and separated from said restricted access area by said protective walls and floors for containing working personnel for operating and maintaining said com-ponents, said components comprising;
a compactor feed hopper disposed in said restricted access area and attached to one of said walls for collecting the nuclear fuel material to be made into nuclear fuel pellets, a star feeder valve disposed in said restricted access area below and laterally to said compactor feed hopper and connected to said compactor feed hopper for controlling the flow from said compactor feed hopper, a roll compactor connected to said star feeder valve and disposed in said restricted access area for rolling said fuel mat-erial into ribbon-like strips of various lengths, a granu-lator connected to said roll compactor and disposed in said restricted access area below and laterally to said roll compactor for granulating said ribbon-like strips into granules, a classifier connected to said granulator and disposed in said restricted access area below and laterally to said granulator for separating said granules according to size and allowing properly sized granules to remain in the process stream, a bulk density check station connected to said classifier and disposed in said restricted access area below and laterally to said classifier for checking the density of said granules, a stearate feed hopper disposed in said restricted access area for collecting stearate mat-erial, a rolling drum connected to said stearate feed hopper and said bulk density check station and disposed in said restricted access area below and laterally to said bulk density check station and said stearate feed hopper for mixing said granules with said stearate, a pellet press feed hopper connected to said rolling drum and disposed in said restricted access area below and laterally to said rolling drum for collecting said mixture of said granules and said stearate, and a pellet press connected to said pellet press feed hopper and partially disposed in said restricted access area and partially disposed in said limited access area and disposed below and laterally to said rolling drum for form-ing said mixture into nuclear fuel pellets, said components being disposed below and laterally relative to the preceding component thereby allowing said nuclear material to flow between said components under the influence of gravity and allowing said components to be vertically manipulated without interfering with the other components.
a restricted access area defined by a plurality of radiation protective vertical walls and horizontal floors offset from each other which contain components for manu-facturing nuclear fuel pellets;
a limited access area defined by said protective walls and floors and separated from said restricted access area by said protective walls and floors for containing working personnel for operating and maintaining said com-ponents, said components comprising;
a compactor feed hopper disposed in said restricted access area and attached to one of said walls for collecting the nuclear fuel material to be made into nuclear fuel pellets, a star feeder valve disposed in said restricted access area below and laterally to said compactor feed hopper and connected to said compactor feed hopper for controlling the flow from said compactor feed hopper, a roll compactor connected to said star feeder valve and disposed in said restricted access area for rolling said fuel mat-erial into ribbon-like strips of various lengths, a granu-lator connected to said roll compactor and disposed in said restricted access area below and laterally to said roll compactor for granulating said ribbon-like strips into granules, a classifier connected to said granulator and disposed in said restricted access area below and laterally to said granulator for separating said granules according to size and allowing properly sized granules to remain in the process stream, a bulk density check station connected to said classifier and disposed in said restricted access area below and laterally to said classifier for checking the density of said granules, a stearate feed hopper disposed in said restricted access area for collecting stearate mat-erial, a rolling drum connected to said stearate feed hopper and said bulk density check station and disposed in said restricted access area below and laterally to said bulk density check station and said stearate feed hopper for mixing said granules with said stearate, a pellet press feed hopper connected to said rolling drum and disposed in said restricted access area below and laterally to said rolling drum for collecting said mixture of said granules and said stearate, and a pellet press connected to said pellet press feed hopper and partially disposed in said restricted access area and partially disposed in said limited access area and disposed below and laterally to said rolling drum for form-ing said mixture into nuclear fuel pellets, said components being disposed below and laterally relative to the preceding component thereby allowing said nuclear material to flow between said components under the influence of gravity and allowing said components to be vertically manipulated without interfering with the other components.
2. The system according to claim 1 wherein said components are disposed in close proximity to said pro-tective vertical walls and wherein said protective vertical walls have glove holes therein for providing access to said components from said limited access area.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US76548577A | 1977-02-04 | 1977-02-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1081436A true CA1081436A (en) | 1980-07-15 |
Family
ID=25073680
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA295,976A Expired CA1081436A (en) | 1977-02-04 | 1978-01-31 | Remote nuclear green pellet processing system |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5397197A (en) |
| BE (1) | BE863648A (en) |
| CA (1) | CA1081436A (en) |
| DE (1) | DE2803808A1 (en) |
| ES (1) | ES466430A1 (en) |
| FR (1) | FR2379885A1 (en) |
| GB (1) | GB1588606A (en) |
| IT (1) | IT1092410B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59174529U (en) * | 1983-05-10 | 1984-11-21 | 三菱電機株式会社 | Ceiling air conditioner |
| FR2562309B1 (en) * | 1984-03-30 | 1989-06-02 | Cogema Framatome Cfc | PLANT FOR THE PRODUCTION OF SINTERABLE OXIDIZED NUCLEAR FUEL GRANULES |
| JPH0310118U (en) * | 1989-06-14 | 1991-01-30 | ||
| DE19812320C1 (en) * | 1998-03-20 | 1999-11-04 | Siemens Ag | Process for producing nuclear fuel sintered bodies and corresponding sintered bodies |
| CN116864168B (en) * | 2023-06-09 | 2024-05-17 | 武汉科技大学 | Nuclear fuel microsphere dressing method and equipment |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL247542A (en) * | 1959-01-20 | |||
| GB1397014A (en) * | 1972-04-13 | 1975-06-11 | Atomic Energy Of Australia | Fabrication process for nuclear fuel pellets |
-
1978
- 1978-01-27 ES ES466430A patent/ES466430A1/en not_active Expired
- 1978-01-28 DE DE19782803808 patent/DE2803808A1/en not_active Withdrawn
- 1978-01-31 FR FR7802690A patent/FR2379885A1/en active Granted
- 1978-01-31 CA CA295,976A patent/CA1081436A/en not_active Expired
- 1978-02-02 JP JP994078A patent/JPS5397197A/en active Granted
- 1978-02-02 GB GB4225/78A patent/GB1588606A/en not_active Expired
- 1978-02-03 BE BE184900A patent/BE863648A/en not_active IP Right Cessation
- 1978-02-03 IT IT19949/78A patent/IT1092410B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| ES466430A1 (en) | 1979-02-01 |
| IT1092410B (en) | 1985-07-12 |
| FR2379885A1 (en) | 1978-09-01 |
| FR2379885B1 (en) | 1984-02-17 |
| JPS5640319B2 (en) | 1981-09-19 |
| JPS5397197A (en) | 1978-08-25 |
| DE2803808A1 (en) | 1978-08-10 |
| BE863648A (en) | 1978-08-03 |
| IT7819949A0 (en) | 1978-02-03 |
| GB1588606A (en) | 1981-04-29 |
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