JP5408622B2 - Crucible cover and alloy fuel production equipment - Google Patents

Description

  The present invention relates to a crucible cover used in an alloy fuel production apparatus for producing a TRU alloy fuel containing super uranium (TRU) element generated from spent fuel of a light water reactor and a fast reactor, and an alloy to which such a crucible cover is applied. The present invention relates to a fuel manufacturing apparatus.

Among spent fuels from spent fuels in light water reactors and fast reactors, neptunium 237 ( ²³⁷ Np), americium-241 ( ²⁴¹ Am), americium 243 ( ²⁴³ Am),
Trans-Uranium (hereinafter referred to as TRU element) such as curium-242 ( ²⁴² Cm) and curium- ²⁴⁴ ( ²⁴⁴ Cm) is included, and minor actinoids obtained by removing plutonium (Pu) from this TRU element Some elements (hereinafter referred to as MA elements) have half-lives of 2.14 million years, 432 years, such as ²³⁷ Np, ²⁴¹ Am, and ²⁴³ Am,
There are nuclides (minor actinide nuclides) that are extremely long as 7380 and cannot be eliminated in a short time.

  Currently, spent fuel in light water reactors is dissolved in nitric acid and then recovered by extracting and separating U and Pu by solvent extraction using tributyl phosphate (TBP) as an extractant. In this case, various fission products and the above-mentioned transuranium element remain, and this extraction residual liquid becomes a high-level radioactive liquid waste. Such high-level radioactive liquid waste is disposed of through a nitric acid recovery step and an evaporation concentration step, and finally processing into a solidified glass form before storing it in the deep part of the formation. The reason for such disposal is that the TRU element has a very long half-life as described above, and it is necessary to consider that there is no impact on the environment for a very long time when performing disposal. As a result, the cost for processing becomes very large.

On the other hand, there is a possibility that the TRU element can be effectively used as a fast reactor fuel. If the TRU element is recovered from the above high-level radioactive liquid waste and mixed with the fuel and used, the disposal burden can be reduced and energy resources can be reduced. It is also possible to improve the utilization efficiency. In order to recycle by using TRU element as a new fuel, neptunium, americium and curium were added to an alloy body containing uranium or an alloy body further added with plutonium and formed into a rod shape of several tens of centimeters. It shall be called slag. A fuel to which such a TRU element is added is referred to as a TRU alloy fuel in this specification. The recycling of the TRU element is described in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 9-43389).
Japanese Patent Laid-Open No. 9-43389

  By the way, among TRU elements, americium has high vapor pressure, and in the production process of TRU alloy fuel, in the melting process for alloying, this high vapor pressure americium evaporates. There was a problem that evaporation loss occurred. In addition, there is also a problem that due to evaporation during the production of americium as described above, the inside of the production apparatus is contaminated and the dose is increased.

  In order to solve the above problems, the invention according to claim 1 is a crucible cover that covers an upper part of a crucible for melting an alloy raw material containing a transuranium element and prevents evaporation of high vapor pressure elements. The crucible cover is provided with a through hole for mold insertion.

  The invention according to claim 2 is the crucible cover according to claim 1, wherein the diameter of the through hole on the upper surface side of the crucible cover is the first diameter, and the diameter of the through hole on the lower surface side of the crucible cover. Has a second diameter larger than the first diameter.

  The invention according to claim 3 has a crucible covered with the crucible cover according to claim 1 or claim 2, and melts the alloy raw material containing the transuranium element in the crucible, An inner cylinder member that accommodates a melting portion, a top plate member that is disposed so as to substantially close a vertically upper portion of the inner cylinder member, and an outer cylinder member that accommodates the top plate member and the inner cylinder member This is an alloy fuel production apparatus.

  The invention according to claim 4 is the alloy fuel production apparatus according to claim 3, wherein a refrigerant flow path is formed in the top plate member.

  The present invention is a crucible cover for preventing evaporation and scattering of a high vapor pressure element in which only a through hole for inserting a mold is formed, and it is possible to limit the amount of americium evaporated and scattered from the through hole to a very small amount. Therefore, according to the crucible cover according to the present invention, the evaporation loss of americium can be suppressed, and contamination in the apparatus and an increase in dose can be suppressed.

  Further, according to the alloy fuel manufacturing apparatus according to the present invention, the melting portion for melting the alloy fuel containing the TRU element is accommodated in the double tube structure including the inner cylinder member and the outer cylinder member, and the inner cylinder member A top plate member is arranged vertically above, and high vapor pressure americium is intensively attached to the top plate member of the inner cylinder member in the alloy fuel melting process. The possibility of contaminating this becomes very low, and by recovering the americium adhering to the top plate member, it is possible to suppress the evaporation loss of americium and to suppress the contamination in the apparatus and the increase in the dose. Become.

  Moreover, as a TRU alloy fuel manufacturing apparatus according to the present invention, a mold or a cladding tube used in the TRU alloy fuel manufacturing process by the apparatus, or the like, the TRU element is attached or mixed with the TRU alloy fuel, so that radioactive waste is generated. With regard to materials that must be disposed of, waste can be reduced in volume and decontaminated by evaporating and separating americium having a high vapor pressure by melting at a high temperature.

It is a figure which shows the outline of the alloy fuel manufacturing apparatus with which the crucible cover which concerns on embodiment of this invention is used. It is a figure which shows the outline of the top-plate member in the alloy fuel manufacturing apparatus with which the crucible cover which concerns on embodiment of this invention is used. It is a figure explaining each space divided in the alloy fuel manufacturing apparatus in which the crucible cover concerning the embodiment of the present invention is used. It is a figure explaining the refrigerant | coolant flow path in the top-plate member 150 (disk part 151) of the alloy fuel manufacturing apparatus by which the crucible cover which concerns on embodiment of this invention is used. It is a figure explaining the various aspects of the crucible cover which concerns on embodiment of this invention. It is a figure which shows typically the mode of the melting process in the alloy fuel manufacturing apparatus with which the crucible cover which concerns on embodiment of this invention is used. It is a figure which shows the effect in case the 2nd diameter r2 of the through-hole 143 is larger than the 1st diameter r1 in the crucible cover 142 which concerns on embodiment of this invention. It is a figure which shows the insulation structure of the induction coil introducing | transducing part in the alloy fuel manufacturing apparatus with which the crucible cover which concerns on embodiment of this invention is used. It is a figure which shows the alloy fuel manufacturing process by the alloy fuel manufacturing apparatus with which the crucible cover which concerns on embodiment of this invention is used. It is a figure which shows the alloy fuel manufacturing process by the alloy fuel manufacturing apparatus with which the crucible cover which concerns on embodiment of this invention is used. It is a figure which shows the alloy fuel manufacturing process by the alloy fuel manufacturing apparatus with which the crucible cover which concerns on embodiment of this invention is used.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of an alloy fuel production apparatus in which a crucible cover according to an embodiment of the present invention is used. In FIG. 1, 100 is a TRU alloy fuel production apparatus, 110 is a cylindrical chamber, 111 is a base, 112 is an outer cylinder member, 113 is a coil power introduction port, 114 is a thermocouple introduction port, and 115 is an inert gas introduction port. , 116 is an outer cylinder space exhaust port, 117 is an inner cylinder space exhaust port, 118 is a refrigerant introduction port, 119 is a refrigerant discharge port, 120 is an inner cylinder member, 121 is a first seal structure, and 122 is a second seal structure. , 123 is a third seal structure part, 125 is a diffusion plate, 130 is a lid member, 140 is a base part, 141 is a crucible, 142 is a crucible cover, 143 is a through hole, 145 is an induction coil, 146 is an insulating member, 150 is A top plate member, 151 is a disk portion, 152 is a cylindrical portion, 153 is a through hole, 157 is a recovery surface, 160 is an elevating device, and 161 is a mold.

  An alloy fuel production apparatus according to the present invention is an apparatus for producing a TRU alloy fuel containing uranium or plutonium as a main raw material and added with an MA element. The alloy fuel produced by this apparatus is burned in a fast reactor. Is assumed. The raw materials used in the alloy fuel production apparatus 100 according to the present invention are MA elements generated from spent fuels in light water reactors and fast reactors, uranium and plutonium. These raw materials are melted in the melting part in the alloy fuel production apparatus 100, and then filled in a mold 161 such as a quartz tube and molded into slag. Since the melting step in the alloy fuel manufacturing apparatus 100 needs to be performed in an inert gas atmosphere, the melting portion of the alloy fuel manufacturing apparatus 100 is provided in a predetermined chamber.

  In the TRU alloy fuel manufacturing apparatus 100, the inside of the apparatus is kept airtight by the cylindrical chamber 110 and the lid member 130 arranged vertically above the cylindrical chamber 110. The cylindrical chamber 110 includes a base 111 that constitutes the bottom of the apparatus, and a cylindrical outer cylinder member 112 that is erected from the base 111, and various ports are provided on the outer cylinder member 112. Is provided.

  In the alloy fuel production apparatus 100 according to the present invention, the melting portion for melting the TRU alloy raw material is provided in a space defined by the inner cylinder member 120 and the like in the outer cylinder member 112. As described above, the alloy fuel production apparatus 100 according to the present invention is characterized by having a double-pipe structure composed of the outer cylinder member 112 and the inner cylinder member 120. As an advantage of providing a melting portion in the inner tube member 120 having such a double tube structure, high vapor pressure americium can be kept in the space in the inner tube member 120, and the inner tube member 120 of the apparatus Contamination of the space between the outer cylinder member 112 can be eliminated.

  A top plate member 150 is provided vertically above the inner cylinder member 120 so as to substantially close the space above the inner cylinder member 120. The top plate member 150 is disposed for the purpose of adhering high vapor pressure americium to the bottom thereof, and a flow path for circulating a refrigerant is provided inside the top plate member 150.

FIG. 2 is a diagram showing an outline of the top plate member in the alloy fuel production apparatus 100 in which the crucible cover according to the embodiment of the present invention is used. The top plate member 150 includes a disk portion 151 and the disk portion 151.
And a cylindrical cylindrical portion 152 erected from the periphery. The bottom surface of the disk portion 151 is used as a region (collecting surface 157) for adhering and collecting americium. Further, the disk portion 151 is provided with a through hole 153 through which a mold (quartz tube) 161 is inserted.

  Between the base 111 of the cylindrical chamber 110 and the inner cylinder member 120 is a circumferential first seal structure 121, and between the inner cylinder member 120 and the top plate member 150 (disk portion 151) is a circle. Airtightness is maintained by the circumferential second seal structure portion 122 and between the top plate member 150 (cylindrical portion 152) and the lid member 130 by the circumferential third seal structure portion 123. Therefore, the space in the alloy fuel production apparatus 100 is divided as shown in FIG.

  FIG. 3 is a view for explaining each space partitioned in the alloy fuel production apparatus 100 in which the crucible cover according to the embodiment of the present invention is used. As shown in FIG. 3, in the alloy fuel production apparatus 100 according to the present invention, the space R <b> 1 partitioned by the inner cylinder member 120, the disk portion 151 of the top plate member 150, and the base 111, the top plate member 150 and the lid member. Three spaces R2 partitioned by 130 and space R3 partitioned by the outer cylinder member 112, the inner cylinder member 120, the base 111, and the lid member 130 are formed. Among these spaces, the melting part for melting the TRU alloy raw material is provided in the space R1, so the space contaminated with americium, which is a high vapor pressure radioactive element that evaporates in the melting process, is almost this Since it is limited to the space R1, the contamination does not expand to the entire apparatus as in the prior art.

  Various ports are provided in the outer cylinder member 112 of the cylindrical chamber 110, and one of them is a coil power introduction port 113, and power is supplied from the coil power introduction port 113 to the induction coil 145 constituting the melting portion. Is supplied. Electrical insulation is maintained between the stainless steel inner cylinder member 120 and the conductor of the induction coil 145 by an insulating member 146 as shown in FIG. FIG. 8 is a view showing an insulating structure of the induction coil introducing portion in the alloy fuel production apparatus using the crucible cover according to the embodiment of the present invention, and the coil conductor introduced into the inner cylindrical member 120 from the coil power introducing port 113. FIG.

  A base portion 140 is provided at the bottom of the base 111, and a graphite crucible 141 can be placed on the base portion 140. The induction coil 145 is arranged so as to surround the crucible 141 on the pedestal 140, and when power is supplied to the induction coil 145, the crucible 141 is heated and put into the crucible 141 in advance. The MA element and TRU alloy raw materials such as uranium and plutonium are dissolved. A crucible cover 142 is provided on the upper portion of the crucible 141 so that the molten TRU alloy raw material is not evaporated or scattered. However, the crucible cover 142 is provided with a through-hole 143 for allowing the mold (quartz tube) 161 to pass therethrough, and the high vapor pressure americium diffuses from the through-hole 143 into the space R1 in the apparatus. it's possible.

  Here, the crucible cover 142 of the present invention will be described in more detail. FIG. 5 is a view for explaining various aspects of the crucible cover 142 according to the embodiment of the present invention. In each of FIGS. 5A to 5D, the upper diagram shows a top view of the crucible cover 142, and the lower diagram shows a cross-sectional view of the crucible cover 142. Further, in any crucible cover 142, the through hole 143 is configured such that the diameter r1 on the upper surface side of the crucible cover 142 is different from the diameter r2 on the lower surface side of the crucible cover 142, and the inner wall of the through hole becomes a tapered surface. Has been.

In the crucible cover 142 shown in FIG. 5A, the diameter of the through hole 143 on the lower surface side of the crucible cover 142 (second diameter r2) is the same as the diameter of the through hole 143 on the upper surface side of the crucible cover 142 (first diameter r1). A larger convex shape is formed on the lower surface side of the crucible cover 142 from the peripheral edge to the through hole 143. Further, in the crucible cover 142 shown in FIG. 5B, the diameter (second diameter r2) of the through hole 143 on the lower surface side of the crucible cover 142 is the same as the diameter (first diameter) of the through hole 143 on the upper surface side of the crucible cover 142. It is larger than r1) and is formed on a flat surface from the peripheral edge to the through hole 143 on the lower surface side of the crucible cover 142. 5C, the diameter of the through hole 143 on the upper surface side of the crucible cover 142 (first diameter r1) is equal to the diameter of the through hole 143 on the lower surface side of the crucible cover 142 (second diameter). The convex shape which is larger than r2) and protrudes downward from the peripheral edge to the through hole 143 on the lower surface side of the crucible cover 142 is formed. Further, in the crucible cover 142 shown in FIG. 5D, the diameter of the through hole 143 on the upper surface side of the crucible cover 142 (first diameter r1) is the same as the diameter of the through hole 143 on the lower surface side of the crucible cover 142 (second diameter). It is larger than r2) and is formed on a flat surface from the peripheral edge to the through hole 143 on the lower surface side of the crucible cover 142. When the crucible cover 142 of the four modes of FIGS. 5A to 5D as described above was examined for the evaporation loss of the molten raw material, the diameter of the through hole 143 on the lower surface side of the crucible cover 142 (second diameter r2). ) Is larger than the diameter (first diameter r1) of the through-hole 143 on the upper surface side of the crucible cover 142, and the evaporation loss of the one shown in FIGS. 5A and 5B is small. Further, when comparing the crucible cover 142 of FIG. 5 (A) and FIG. 5 (B), as shown in FIG. 5 (A), the bottom surface of the crucible cover 142 protrudes downward from the peripheral edge to the through hole 143. It has been found that a shape is preferred.

  Note that the crucible cover 142 shown in FIGS. 5C and 5D is not limited to FIGS. 5A and 5B, and only the through hole 143 for inserting the mold (quartz tube) 161 is used. Is a crucible cover 142 for preventing evaporation and scattering of the high vapor pressure element, and the amount of americium that is evaporated and scattered from the through hole 143 can be limited to a very small amount, so that evaporation loss of americium can be suppressed, Contamination in the apparatus can be suppressed.

  Next, a mechanism for preventing evaporation of high vapor pressure elements by the crucible cover 142 according to the embodiment of the present invention will be described. FIG. 6 is a view schematically showing a melting process in the alloy fuel production apparatus in which the crucible cover according to the embodiment of the present invention is used. In FIG. 6, the upper diagram shows a configuration diagram around the crucible, and the lower diagram shows the temperature gradient of the molten alloy in the crucible. In the alloy fuel production apparatus 100 according to the present invention, the TRU alloy raw material in the crucible 141 is melted by high-frequency heating by the induction coil 145. In such a heating method, the heat generated in the crucible 141 is used for the alloy in the crucible 141. Since heat conduction is performed to the raw material, the temperature gradient of the molten alloy has a tendency that the inner wall surface of the crucible 141 is high as shown in FIG. Therefore, in the space between the molten alloy liquid level in the crucible 141 and the lower surface of the crucible cover 142, the inner wall surface of the crucible 141 as shown in FIG. 6 moves toward the center and again toward the molten alloy liquid level near the center. Such convection will occur. Due to such convection, it is assumed that the probability that the high vapor pressure element evaporated from the molten alloy escapes from the space through the through hole 143 and is scattered into the space R1 is extremely low.

Further, when the diameter of the through hole 143 on the lower surface side of the crucible cover 142 (second diameter r2) is larger than the diameter of the through hole 143 on the upper surface side of the crucible cover 142 (first diameter r1), In addition to the high vapor pressure element scattering prevention effect by the crucible cover 142 itself, the high vapor pressure element scattering prevention effect by the tapered surface formed by the inner wall surface of the through hole 143 can also be expected. FIG. 7 is a diagram showing an effect when the second diameter r2 of the through hole 143 is larger than the first diameter r1 in the crucible cover 142 according to the embodiment of the present invention. As shown in FIG. 7, a part of the high vapor pressure element to be scattered from the through hole 143 to the space R <b> 1 is returned to the space between the molten alloy liquid surface and the lower surface of the crucible cover 142 by the tapered surface. Convection. For this reason, when the second diameter r2 of the through-hole 143 is larger than the first diameter r1, the amount of americium evaporated and scattered from the through-hole 143 can be limited to a very small amount, and the evaporation loss of americium is suppressed. It is possible to suppress contamination and high dose in the device.

  Returning again to FIG. The outer cylinder member 112 of the cylindrical chamber 110 is provided with a thermocouple introduction port 114, and the temperature at a predetermined location in the apparatus can be monitored by a thermocouple lead introduced from the thermocouple introduction port 114. It is like that. The location where the temperature is detected by the thermocouple introduced from the port 114 is arbitrary, but examples of candidate locations where the temperature should be detected include the crucible 141, the inner cylinder member 120, and the top plate member 150.

  Further, an inert gas introduction port 115 is provided in the outer cylinder member 112 of the cylindrical chamber 110. From the inert gas introduction port 115, an inert gas such as argon can be introduced into the space R1 and the space R2 in the inner cylinder member 120 through a flexible tube. Argon gas is introduced from the inert gas introduction port 115 when the alloy fuel melting step is performed. In addition, when the molten alloy fuel is formed into slag, an injection casting method is employed, but argon gas is also introduced from the inert gas introduction port 115 during the casting process.

  Further, the outer cylinder member 112 of the cylindrical chamber 110 is provided with an outer cylinder space exhaust port 116, and the space R3 can be exhausted from the outer cylinder space exhaust port 116 by a vacuum pump (not shown). It is like that.

  Further, the outer cylinder member 112 of the cylindrical chamber 110 is provided with an inner cylinder space exhaust port 117. The inner cylinder space exhaust port 117 is connected to the inner cylinder member 120 via a flexible tube. A vacuum pump (not shown) is connected to the inner cylinder space exhaust port 117. By evacuating from the inner cylinder space exhaust port 117 using this pump, the space R1 and the space R2 can be exhausted. It is like that.

  Further, the outer cylinder member 112 of the cylindrical chamber 110 is provided with a refrigerant introduction port 118 and a refrigerant discharge port 119. These ports are connected to the top plate member 150 through flexible tubes, and the temperature of the top plate member 150 is lowered by the refrigerant introduced from the refrigerant introduction port 118. The refrigerant that has passed through the refrigerant flow path in the top plate member 150 is discharged from the refrigerant discharge port 119. In addition, as a refrigerant | coolant used for cooling the top-plate member 150, it is possible to use both gas and a liquid.

  Next, the flow path of the refrigerant introduced from the refrigerant introduction port 118 and discharged from the refrigerant discharge port 119 will be described. FIG. 4 is a diagram illustrating a refrigerant flow path in the top plate member 150 (disk portion 151) of the alloy fuel production apparatus in which the crucible cover according to the embodiment of the present invention is used. The disk portion 151 of the top plate member 150 is hollow, and this hollow portion serves as a flow path for the refrigerant introduced from the refrigerant introduction port 118. Further, a fin member 156 is provided so as to stand upright in the hollow portion, so that the cooling efficiency of the disk portion 151 is improved. In the embodiment shown in FIG. 4, two fin members 156 are provided, but more fin members 156 can be provided in order to further improve the cooling efficiency of the top plate member 150, Various arrangements can be adopted for the arrangement of the fin members 156. The refrigerant that passes through the hollow part of the top plate member 150 and cools the disk part 151 is discharged from the refrigerant discharge port 119.

As described above, the disk portion 151 of the top plate member 150 cooled by the refrigerant efficiently captures the americium evaporated in the melting step on the recovery surface 157 on the bottom surface. In the melting step, the TRU alloy raw material is melted by high-frequency heating by the induction coil 145. At this time, a small amount of evaporated material (americium) evaporated and diffused in the space R1 does not easily adhere to the side wall of the inner cylinder member 120. It is assumed that the floating will continue due to the convection of the atmospheric gas. On the other hand, the top plate member 150 provided on the upper portion of the inner cylinder member 120 has a temperature lower than that of the inner cylinder member 120 due to the cooling by the refrigerant as described above, and the floating evaporated substance is preferentially deposited.

  As an alloy fuel production device, it is possible to efficiently recover a little vaporized and evaporated material (Americium) in order to prevent contamination within the device, or to manage the exposure of workers and the measurement of nuclear fuel materials. Although it is necessary from the viewpoint, according to the alloy fuel manufacturing apparatus 100 according to the present embodiment, it is possible to efficiently evaporate the collection surface 157 of the top plate member 150, so that these needs are satisfied. Can do.

  Also, in the alloy fuel production equipment, the side of the normal single-structure chamber needs to be cooled because it is in contact with workers, manipulators or other substances (air cooling / water cooling). When manufactured, if the side surface of the chamber is at room temperature, preferential deposition of the evaporating substance occurs over a wide range. Therefore, as in the alloy fuel production apparatus 100 according to the present embodiment, it is important to install a low temperature part other than the side wall in the chamber.

  Next, an alloy fuel production procedure by the alloy fuel production apparatus 100 according to this embodiment configured as described above will be described. 9 to 11 are views showing an alloy fuel production process by an alloy fuel production apparatus in which the crucible cover according to the embodiment of the present invention is used.

  First, when the melting process is performed by the alloy fuel manufacturing apparatus 100, after the MA element and TRU alloy raw materials such as uranium and plutonium are put into the crucible 141, the crucible cover 142 is put on the crucible 141, and the lid member 130 is set. The outer cylinder space exhaust port 116 exhausts the space R3, and the inner cylinder space exhaust port 117 exhausts the space R1 and the space R2. Next, argon gas is introduced from the inert gas introduction port 115 into the space R1 and the space R2.

  After the atmosphere adjustment in the apparatus as described above is performed, the melting step is performed (FIG. 9). In this melting step, electric power is supplied to the induction coil 145, and the TRU alloy raw material in the crucible 141 is melted by high-frequency heating by the induction coil 145.

  After the TRU alloy raw material in the crucible 141 is sufficiently melted in the melting process, an injection casting process is performed to mold the TRU alloy into slag. In this injection casting process, the inner cylinder space exhaust port 117 exhausts the argon gas in the space R1 and the space R2. At the same time, the space R3 is also exhausted by the outer cylinder space exhaust port 116. And after making the space in the alloy fuel manufacturing apparatus 100 into a vacuum state by each exhaust port as mentioned above, the mold 161 is lowered | hung with the raising / lowering apparatus 160, The one end is made into the molten TRU alloy raw material in the crucible 141. Immerse it (Fig. 10). Next, argon gas is introduced into the space R1 and the space R2 from the inert gas introduction port 115, and these spaces are pressurized. Then, pressure is applied to the liquid surface of the molten TRU alloy raw material in the crucible 141, and the molten TRU alloy flows into the mold 161 as shown in FIG. Thus, the TRU alloy fuel slag-ized in the mold 161 can be obtained by natural or forced cooling while the TRU alloy is injected into the mold 161.

As described above, according to the alloy fuel manufacturing apparatus described above, the melting portion for melting the alloy fuel containing the TRU element is accommodated in the double tube structure including the inner cylinder member and the outer cylinder member, and vertically above the inner cylinder member. In the alloy fuel melting process, the high vapor pressure americium concentrates on the top plate member of the inner cylinder member, so that it adheres to other parts of the device and attaches it. The possibility of contamination and a high dose becomes very low, and by collecting americium adhering to the top plate member, it becomes possible to suppress evaporation loss of americium.

  Further, the present invention is a crucible cover for preventing evaporation and scattering of a high vapor pressure element in which only a through hole for inserting a mold is formed, and it is possible to limit the amount of americium evaporated and scattered from the through hole to a very small amount. Therefore, according to the crucible cover according to the present invention, evaporation loss of americium can be suppressed and contamination in the apparatus can be suppressed.

  Moreover, as a TRU alloy fuel manufacturing apparatus according to the present invention, a mold or a cladding tube used in the TRU alloy fuel manufacturing process by the apparatus, or the like, the TRU element is attached or mixed with the TRU alloy fuel, so that radioactive waste is generated. With regard to materials that must be disposed of, waste can be reduced in volume and decontaminated by evaporating and separating americium having a high vapor pressure by melting at a high temperature.

DESCRIPTION OF SYMBOLS 100 ... TRU alloy fuel manufacturing apparatus 110 ... Cylindrical chamber 111 ... Base 112 ... Outer cylinder member 113 ... Coil electric power introduction port 114 ... Thermocouple introduction port 115 ... Non Active gas introduction port 116 ... outer cylinder space exhaust port 117 ... inner cylinder space exhaust port 118 ... refrigerant introduction port 119 ... refrigerant discharge port 120 ... inner cylinder member 121 ... first seal Structure part 122 ... second seal structure part 123 ... third seal structure part 125 ... diffusion plate 130 ... lid member 140 ... base part 141 ... crucible 142 ... crucible cover 143 ... through-hole 145 ... induction coil 146 ... insulating member 150 ... top plate member 151 ... disc part 152 ... cylindrical part 153 ... through-hole 156 ... fin member 157 ..Times Surface 160 ... lifting device 161 ... mold

Claims (4)

A crucible cover that covers the upper part of the crucible that melts the alloy raw material containing the transuranium element and prevents evaporation of high vapor pressure elements,
The crucible cover, wherein the crucible cover is provided with a through hole for mold insertion. The diameter of the through hole on the upper surface side of the crucible cover is a first diameter,
The crucible cover according to claim 1, wherein a diameter of the through hole on the lower surface side of the crucible cover is a second diameter larger than the first diameter. A melting part having a crucible covered with the crucible cover according to claim 1 or 2, and melting an alloy raw material containing a transuranium element in the crucible,
An inner cylinder member that accommodates the melting portion;
A top plate member arranged so as to substantially block the vertical upper side of the inner cylinder member;
An alloy fuel production apparatus comprising: the top plate member; and an outer cylinder member that accommodates the inner cylinder member. The alloy fuel manufacturing apparatus according to claim 3, wherein a refrigerant flow path is formed in the top plate member.

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