JPH04301595A - Manufacture of spherical nuclear fuel particle - Google Patents
Manufacture of spherical nuclear fuel particleInfo
- Publication number
- JPH04301595A JPH04301595A JP3066621A JP6662191A JPH04301595A JP H04301595 A JPH04301595 A JP H04301595A JP 3066621 A JP3066621 A JP 3066621A JP 6662191 A JP6662191 A JP 6662191A JP H04301595 A JPH04301595 A JP H04301595A
- Authority
- JP
- Japan
- Prior art keywords
- fuel particles
- nuclear fuel
- droplets
- particles
- ammonia
- 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.)
- Withdrawn
Links
- 239000002245 particle Substances 0.000 title claims abstract description 70
- 239000003758 nuclear fuel Substances 0.000 title claims abstract description 32
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000011230 binding agent Substances 0.000 claims abstract description 17
- 239000000654 additive Substances 0.000 claims abstract description 8
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 8
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 7
- 239000011347 resin Substances 0.000 claims description 33
- 229920005989 resin Polymers 0.000 claims description 33
- 239000011550 stock solution Substances 0.000 claims description 25
- 239000007864 aqueous solution Substances 0.000 claims description 13
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 12
- 230000001112 coagulating effect Effects 0.000 claims description 12
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 12
- 150000003671 uranium compounds Chemical class 0.000 claims 1
- 239000000446 fuel Substances 0.000 abstract description 18
- 229910052770 Uranium Inorganic materials 0.000 abstract description 14
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 abstract description 14
- 239000007788 liquid Substances 0.000 abstract description 12
- 238000007711 solidification Methods 0.000 abstract description 4
- 230000008023 solidification Effects 0.000 abstract description 4
- 230000002950 deficient Effects 0.000 abstract 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 32
- 230000015271 coagulation Effects 0.000 description 21
- 238000005345 coagulation Methods 0.000 description 21
- 238000000034 method Methods 0.000 description 12
- 229910021529 ammonia Inorganic materials 0.000 description 10
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 230000032683 aging Effects 0.000 description 6
- 230000007547 defect Effects 0.000 description 6
- 230000005070 ripening Effects 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 229910002007 uranyl nitrate Inorganic materials 0.000 description 6
- 238000001035 drying Methods 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 229910002804 graphite Inorganic materials 0.000 description 4
- 239000010439 graphite Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000002253 acid Substances 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000006303 photolysis reaction Methods 0.000 description 3
- 239000002296 pyrolytic carbon Substances 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 229910010271 silicon carbide Inorganic materials 0.000 description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- BSYVTEYKTMYBMK-UHFFFAOYSA-N tetrahydrofurfuryl alcohol Chemical compound OCC1CCCO1 BSYVTEYKTMYBMK-UHFFFAOYSA-N 0.000 description 2
- 239000002562 thickening agent Substances 0.000 description 2
- 125000005289 uranyl group Chemical group 0.000 description 2
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 description 1
- 229910052778 Plutonium Inorganic materials 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 229910052776 Thorium Inorganic materials 0.000 description 1
- 239000001089 [(2R)-oxolan-2-yl]methanol Substances 0.000 description 1
- DHKHKXVYLBGOIT-UHFFFAOYSA-N acetaldehyde Diethyl Acetal Natural products CCOC(C)OCC DHKHKXVYLBGOIT-UHFFFAOYSA-N 0.000 description 1
- 125000002777 acetyl group Chemical class [H]C([H])([H])C(*)=O 0.000 description 1
- 150000003868 ammonium compounds Chemical class 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000007771 core particle Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- PSHRANCNVXNITH-UHFFFAOYSA-N dimethylamino acetate Chemical compound CN(C)OC(C)=O PSHRANCNVXNITH-UHFFFAOYSA-N 0.000 description 1
- 238000000855 fermentation Methods 0.000 description 1
- 230000004151 fermentation Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 230000004992 fission Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000001879 gelation Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000001782 photodegradation Methods 0.000 description 1
- 230000015843 photosynthesis, light reaction Effects 0.000 description 1
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- -1 uranyl nitrate Chemical class 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
Classifications
-
- 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
Landscapes
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
Abstract
Description
【０００１】0001
【産業上の利用分野】この発明は球状核燃料粒子の製造
方法に関し、更に詳しくは、真球度が良好であり、かつ
均一な燃料核を得るのに好適な球状核燃料粒子の製造方
法に関するものである。[Field of Industrial Application] This invention relates to a method for producing spherical nuclear fuel particles, and more particularly, to a method for producing spherical nuclear fuel particles that have good sphericity and are suitable for obtaining uniform fuel nuclei. be.
【０００２】0002
【従来の技術と発明が解決しようとする課題】球状核燃
料粒子として、ウラン（Ｕ）、トリウム（Ｔｈ）、プル
トニウム（Ｐｕ）等の核***物質の酸化物、またはそれ
らの混合物等を、直径３００〜８００ミクロン程度の小
球体に形成したものがある。[Prior Art and Problems to be Solved by the Invention] As spherical nuclear fuel particles, oxides of fissile materials such as uranium (U), thorium (Th), and plutonium (Pu), or mixtures thereof, are used as spherical nuclear fuel particles with a diameter of 300 to Some are formed into small spheres of about 800 microns.
【０００３】そして、この球状核燃料粒子の表面に、通
常、熱分解炭素及び炭化硅素等のセラミックスを多重に
被覆してなる被覆燃料粒子を、円筒状若しくは球状の黒
鉛コンポジット成型体に分散せしめたものを高温ガス型
原子炉用燃料として使用している。[0003] Then, coated fuel particles, which are usually made by coating the surface of these spherical nuclear fuel particles in multiple layers with ceramics such as pyrolytic carbon and silicon carbide, are dispersed in a cylindrical or spherical graphite composite molded body. is used as fuel for high-temperature gas reactors.
【０００４】ここで、被覆された球状核燃料粒子の真球
度（真球の程度は核燃料粒子の最大径と最少径の比とし
て規定される。）が良好である程、黒鉛マトリックス中
に埋め込まれて成型される成型工程中において、又は原
子炉運転中において欠陥を生じる割合が小さい。このた
め、核燃料粒子を選別し、真球度の高いものを使用する
のが通常である。[0004] Here, the better the sphericity of the coated spherical nuclear fuel particles (the degree of sphericity is defined as the ratio of the maximum diameter to the minimum diameter of the nuclear fuel particles), the more embedded they are in the graphite matrix. The rate of defects occurring during the molding process or during nuclear reactor operation is low. For this reason, it is common practice to select nuclear fuel particles and use those with high sphericity.
【０００５】被覆された核燃料粒子の真球度を良好に保
つには、芯となる球状核燃料粒子の真球度の高いことが
必要である。球状核燃料粒子の真球度が少しでも悪いと
、被覆されるにつれて形状の歪が増幅され、真球度が低
下していくからである。[0005] In order to maintain good sphericity of the coated nuclear fuel particles, it is necessary that the core spherical nuclear fuel particles have high sphericity. This is because if the sphericity of the spherical nuclear fuel particles is even slightly poor, the shape distortion will be amplified as the particles are coated, and the sphericity will decrease.
【０００６】従来、球状核燃料粒子の製造方法としては
、核***物質を硝酸等の酸に溶解し、これにバインダー
樹脂および光分解停止剤等の添加物を適宜に加えた水溶
性原液を、アンモニア水溶液からなる凝固槽に滴下して
液滴を凝固せしめ、その後、乾燥、焙焼、燒結を行なう
ことにより、金属酸化物である球状核燃料粒子を得る方
法が知られている。Conventionally, as a method for producing spherical nuclear fuel particles, nuclear fissile material is dissolved in an acid such as nitric acid, and a water-soluble stock solution is prepared by adding appropriate additives such as a binder resin and a photodegradation stopper, and then dissolved in an aqueous ammonia solution. A known method is to obtain spherical nuclear fuel particles, which are metal oxides, by dropping the droplets into a coagulation tank consisting of a liquid droplet and solidifying the droplets, followed by drying, roasting, and sintering.
【０００７】すなわち、例えば、核燃料金属元素の塩の
水溶液又は核燃料金属元素の酸化物のゾル、及び適当な
バインダー樹脂を含む樹脂からなる原液を小滴化し、こ
の小滴をアンモニアガス及びアンモニア水中に通過させ
、小球体に凝固させることによって得られる（外部ゲル
化法）。That is, for example, a stock solution consisting of an aqueous solution of a salt of a nuclear fuel metal element or a sol of an oxide of a nuclear fuel metal element, and a resin containing a suitable binder resin is formed into droplets, and the droplets are placed in ammonia gas and ammonia water. Obtained by passing through and coagulating into spherules (external gelation method).
【０００８】この場合、原液が滴下ノズルから吐出され
た液滴が凝固液面に着水し、凝固液により液滴が凝固し
、その結果として凝固液中で多量の水を含んだゲル状粒
子が形成されるのであるが、この一連の過程におけるバ
インダー樹脂の特性が粒子の変形に著しい影響を与える
。In this case, droplets of the stock solution discharged from the dropping nozzle land on the surface of the coagulating liquid, and the droplets are coagulated by the coagulating liquid, resulting in gel-like particles containing a large amount of water in the coagulating liquid. are formed, but the properties of the binder resin during this series of processes have a significant effect on the deformation of the particles.
【０００９】特に滴下ノズルより液滴を形成せしめる工
程において、振動により液滴の分離を行なう場合、一般
に液滴の着水までの時間が短いので、バインダー樹脂を
正しく選択しなければ、滴下ノズルから吐出されてから
着水するまで間での変形が著しくなる。In particular, in the process of forming droplets from the dripping nozzle, when the droplets are separated by vibration, the time required for the droplets to land on the water is generally short, so if the binder resin is not selected correctly, the droplets will separate from the dripping nozzle. The deformation becomes significant between the time it is discharged and the time it lands on the water.
【００１０】このような振動滴下に適合したバインダー
樹脂の一例としてはＰＶＡ（ポリビニルアルコール）樹
脂を挙げることができる。An example of a binder resin suitable for such vibratory dropping is PVA (polyvinyl alcohol) resin.
【００１１】しかしながら、ＰＶＡ樹脂添加の粒子は凝
固が遅く、アンモニア水溶液中に長時間保持しても、粒
子の中心部は不均一になり、後工程での乾燥、焙焼、燒
結での『割れ』等の粒子欠陥の原因となっているという
問題点を有している。However, particles containing PVA resin solidify slowly, and even if kept in an ammonia aqueous solution for a long time, the center of the particles becomes uneven, resulting in ``cracking'' during drying, roasting, and sintering in the subsequent process. The problem is that it causes particle defects such as '.
【００１２】この発明は前記事情に基づいてなされたも
のである。すなわち、本発明の目的は、球状核燃料粒子
の製造方法に関し、ウラン原液液滴の凝固、熟成をアン
モニアガス、あるいはアンモニア水溶液の共存状態にお
いて加圧条件下で行なうことにより、球状核燃料粒子の
真球度が良好であり、より均一な燃料粒子を得るのに好
適な球状核燃料粒子の製造方法を提供しようとするもの
である。[0012] This invention has been made based on the above circumstances. That is, the object of the present invention is to produce true spheres of spherical nuclear fuel particles by coagulating and ripening droplets of uranium stock solution under pressurized conditions in the coexistence of ammonia gas or aqueous ammonia solution. It is an object of the present invention to provide a method for producing spherical nuclear fuel particles that have good consistency and are suitable for obtaining more uniform fuel particles.
【００１３】[0013]
【前記課題を解決するための手段】前記課題を解決すべ
く本発明者が鋭意検討した結果、従来の粒子形成には好
適であるが、一方、凝固が遅く、後工程での欠陥の発生
するウラン原液を使用する燃料核製造工程において、ア
ンモニア浴中での凝固を加圧状態で実施することにより
、上述した問題点を解消し得る事を見出して本発明に到
達した。[Means for Solving the Problems] As a result of intensive studies by the present inventors to solve the problems described above, it has been found that although it is suitable for conventional particle formation, solidification is slow and defects occur in subsequent steps. The present invention has been achieved by discovering that the above-mentioned problems can be solved by performing solidification in an ammonia bath under pressure in a fuel nuclear production process that uses uranium stock solution.
【００１４】前記課題を解決するための請求項１に記載
の発明は、ウランを硝酸に溶解しさらにバインダー樹脂
等の添加剤を加えた原液を、アンモニア水溶液中に滴下
し、アンモニア水浴中で形成される凝固液滴を加圧条件
下で熟成することを特徴とする球状核燃料粒子の製造方
法であり、前記課題を解決するための請求項２に記載の
発明は、前記請求項１に記載のバインダー樹脂としてポ
リビニルアルコール樹脂あるいはアルカリ条件下で凝固
する性質を有する樹脂を用いることを特徴とする前記請
求項１に記載の球状核燃料粒子の製造方法である。[0014] The invention as set forth in claim 1 for solving the above problem is such that a stock solution in which uranium is dissolved in nitric acid and additives such as a binder resin are added thereto is dropped into an ammonia aqueous solution, and the solution is formed in an ammonia water bath. A method for producing spherical nuclear fuel particles characterized by ripening solidified droplets under pressurized conditions. 2. The method for producing spherical nuclear fuel particles according to claim 1, wherein a polyvinyl alcohol resin or a resin having a property of coagulating under alkaline conditions is used as the binder resin.
【００１５】以下、さらに本発明の製造方法について詳
細に説明する。The manufacturing method of the present invention will be further explained in detail below.
【００１６】本発明の方法は、従来の球状核燃料粒子の
製造方法、すなわち、核***物質を硝酸等の酸に溶解し
、これにバインダー樹脂および添加剤を適宜加えた水溶
性原液を、アンモニア水溶液からなる凝固浴に滴下し、
液滴を凝固させ、その後、乾燥、焙焼、燒結を行なうこ
とにより、金属酸化物である球状核燃料粒子を得る方法
に適用することができる。The method of the present invention is similar to the conventional method for producing spherical nuclear fuel particles, that is, a water-soluble stock solution in which fissile material is dissolved in an acid such as nitric acid and a binder resin and additives are appropriately added thereto is prepared from an ammonia aqueous solution. drop into a coagulation bath,
It can be applied to a method for obtaining spherical nuclear fuel particles, which are metal oxides, by solidifying droplets and then drying, roasting, and sintering.
【００１７】その内でも、ウランを硝酸に溶解して硝酸
ウラニルを形成し、バインダー樹脂等の添加剤を加えた
原液を、アンモニア水溶液中に滴下し、凝固させてなる
球状核燃料粒子の製造方法に好適に適用する事ができる
。Among them, a method for producing spherical nuclear fuel particles in which uranium is dissolved in nitric acid to form uranyl nitrate, and a stock solution containing additives such as a binder resin is dropped into an ammonia aqueous solution and solidified. It can be suitably applied.
【００１８】原液成分としては、たとえば、重ウラン酸
アンモニウム粒子を製造する場合には、硝酸ウラニル溶
液が用いられる。As the stock solution component, for example, when producing ammonium deuterate particles, a uranyl nitrate solution is used.
【００１９】また、原液は増粘剤としてバインダー樹脂
等を含有するのが好ましい。前記ウランを硝酸に溶解し
たものや、硝酸ウラニル溶液が増粘剤を含有すると、原
液をアンモニア水溶液中に滴下して生じる適下粒の変形
を防止することができ、より良好な真球度で、より低い
破損率で燃料粒子を製造することができる。[0019] Furthermore, the stock solution preferably contains a binder resin or the like as a thickener. When the uranium dissolved in nitric acid or the uranyl nitrate solution contains a thickener, it is possible to prevent the deformation of the lower grains that occurs when the undiluted solution is dropped into an ammonia aqueous solution, resulting in better sphericity. , fuel particles can be produced with a lower failure rate.
【００２０】前記バインダー樹脂としては、ポリビニル
アルコ−ル樹脂あるいはアルカリ条件下で凝固する性質
を有する樹脂を用いることができる。As the binder resin, a polyvinyl alcohol resin or a resin having a property of coagulating under alkaline conditions can be used.
【００２１】アルカリ条件下で凝固する性質を有する樹
脂としては、樹脂単独でもアルカリ雰囲気中で凝固性能
を有するもの、例えばポリビニルアセタール／Ｎ；Ｎ−
ジメチルアミノアセテート酸中和物（商品名 ＡＥＡ
，三共製）等を挙げることができる。[0021] Examples of resins that have the property of coagulating under alkaline conditions include those that have the ability to coagulate in an alkaline atmosphere even when the resin alone has the property of coagulating in an alkaline atmosphere, such as polyvinyl acetal/N;
Dimethylaminoacetate acid neutralized product (product name: AEA
, Sankyo), etc.
【００２２】本発明においては、ポリビニルアルコール
樹脂を特に好ましく用いることができる。In the present invention, polyvinyl alcohol resin can be particularly preferably used.
【００２３】本発明に好適な原液組成の一例としては、
ウランが硝酸ウラニルとして濃度１００ｇＵ／リットル
〜４００ｇＵ／リットル、バインダー樹脂が２ｇ／リッ
トルより５０ｇ／リットルとして含有されているものを
挙げることができる。[0023] An example of a stock solution composition suitable for the present invention is:
Examples include those containing uranium as uranyl nitrate at a concentration of 100 gU/liter to 400 gU/liter and binder resin at a concentration of 2 to 50 g/liter.
【００２４】また、原液中に光分解停止剤や、原液の表
面張力を調整する為の界面活性剤等の添加剤を適宜に含
有することが好ましい。光分解停止剤としては、バイン
ダー樹脂の光分解（ウランが触媒となる）を防止する効
果のある物質、例えばテトラハイドロフルフリルアルコ
ール（４ＨＦ）やポリエチレングリコール等を挙げるこ
とができる。[0024] Furthermore, it is preferable that additives such as a photolysis stopper and a surfactant for adjusting the surface tension of the stock solution are appropriately contained in the stock solution. Examples of the photodecomposition stopper include substances that are effective in preventing photodecomposition of the binder resin (uranium serves as a catalyst), such as tetrahydrofurfuryl alcohol (4HF) and polyethylene glycol.
【００２５】本発明の球状核燃料粒子は、原液の液滴を
凝固液中に滴下することにより製造される。The spherical nuclear fuel particles of the present invention are produced by dropping droplets of a stock solution into a coagulating solution.
【００２６】原液の液滴化方法は、特に制限がないので
あるが、たとえば、細径のノズルを適宜の手段で振動さ
せることにより実現することができる。[0026] There is no particular restriction on the method of turning the stock solution into droplets, but it can be realized, for example, by vibrating a small-diameter nozzle by an appropriate means.
【００２７】ウラン原液を、滴下ノズルを振動させる等
の手段を用い、液滴を形成させるが、液滴が着水するま
での空間において、液滴の表面が硬化を開始するように
するのが、着水時の変形を防止するために望ましい。[0027] The uranium stock solution is formed into droplets using means such as vibrating the dropping nozzle, but it is best to make the surface of the droplet start to harden in the space until the droplet lands on the water. , desirable to prevent deformation when landing on water.
【００２８】よって、この空間がアンモニアガスにより
充たされていることが望ましい。アンモニアガスは凝固
槽から発生するアンモニアガスでもよいが、原液の組成
によってはアンモニアガスを液滴が着水するまでの空間
に強制的に放出し、その空間内のアンモニア濃度を調整
することも時により必要である。[0028] Therefore, it is desirable that this space is filled with ammonia gas. The ammonia gas may be ammonia gas generated from a coagulation tank, but depending on the composition of the stock solution, it is sometimes possible to forcefully release ammonia gas into the space until the droplets land on the water and adjust the ammonia concentration in that space. It is necessary due to
【００２９】凝固液として好適に使用されるのは、通常
、２０重量％〜飽和濃度の濃厚アンモニア水溶液である
。A concentrated ammonia aqueous solution having a concentration of 20% by weight to saturation is preferably used as the coagulating liquid.
【００３０】濃厚アンモニウム水溶液を採用すると、そ
の液面上はアンモニア蒸気の雰囲気となっているから、
濃厚アンモニウム水溶液に落下する前記原液の液滴が前
記アンモニア蒸気雰囲気中を通過する間に、凝固を開始
して、液滴の表面に凝固皮膜が形成される。そしてその
凝固皮膜の形成によって、液滴が原液の液面に衝突する
際の粒子形状の変形が防止される。この凝固皮膜は、ア
ンモニアとの反応により金属塩、例えば硝酸ウラニルが
重ウラン酸アンモン（ＡＤＵ）の様なアンモニウム化合
物に転化することにより、形成される。[0030] When a concentrated ammonium aqueous solution is used, there is an atmosphere of ammonia vapor above the liquid surface.
While the droplets of the stock solution falling into the concentrated ammonium aqueous solution pass through the ammonia vapor atmosphere, coagulation starts and a coagulated film is formed on the surface of the droplets. The formation of the solidified film prevents deformation of the particle shape when the droplets collide with the liquid surface of the stock solution. This coagulated film is formed by converting a metal salt, such as uranyl nitrate, into an ammonium compound such as ammonium diurate (ADU) by reaction with ammonia.
【００３１】形成された粒子の量が多い場合には、粒子
が重畳した状態で凝固浴中に滞留することにより粒子の
破損を生じることがあるので、このような粒子の破損を
防止するために凝固槽のアンモニア水溶液を循環させる
ことも好ましい。[0031] If a large amount of particles are formed, the particles may remain in the coagulation bath in a superimposed state, resulting in particle breakage; therefore, in order to prevent such particle breakage, It is also preferable to circulate the ammonia aqueous solution in the coagulation tank.
【００３２】本発明の球状核燃料粒子の製造方法におい
ては、ウランおよびバインダー樹脂等の添加剤を加えた
原液の液滴をアンモニア水浴中に滴下して得られる凝固
液滴を加圧条件下で熟成する。In the method for producing spherical nuclear fuel particles of the present invention, droplets of a stock solution containing uranium and additives such as a binder resin are dropped into an ammonia water bath, and the resulting solidified droplets are aged under pressurized conditions. do.
【００３３】熟成は、凝固液滴を形成するアンモニア凝
固液の装填された凝固槽にて、一定量の凝固液滴が得ら
れてから、その凝固槽内を加圧することにより行うこと
もできるし、また凝固槽で得られた凝固液滴を集めて別
の加圧可能な熟成槽に移動し、その熟成槽中で行っても
良い。熟成槽中で熟成する場合、凝固液滴と共にアンモ
ニア凝固液が熟成槽中に同伴されても良い。[0033] Aging can also be carried out by pressurizing the inside of the coagulation tank after a certain amount of coagulation droplets have been obtained in a coagulation tank filled with an ammonia coagulation solution that forms coagulation droplets. Alternatively, the solidified droplets obtained in the coagulation tank may be collected and transferred to another pressurized ripening tank, and the fermentation may be carried out in that ripening tank. In the case of aging in the aging tank, the ammonia coagulation liquid may be entrained into the aging tank together with the coagulation droplets.
【００３４】また、加圧の際の雰囲気は、凝固液滴に対
して不活性な気体であれば特に制限がないのであるが、
凝固を更に促進するためにアンモニアガスとするのが好
ましい。また、凝固中の粒子の過度の乾燥を防止するた
めに、アンモニアガス中で行なう場合であっても、湿っ
た雰囲気で行なうことが必要である。[0034] Furthermore, the atmosphere during pressurization is not particularly limited as long as it is a gas that is inert to the solidified droplets.
Ammonia gas is preferably used to further promote coagulation. Further, in order to prevent excessive drying of particles during coagulation, it is necessary to carry out the process in a humid atmosphere even when carrying out the process in ammonia gas.
【００３５】加圧圧力は大きいほど望ましい。圧力が大
きいほど反応が速くなる。しかし、加圧槽の耐圧への要
求性能を考慮すると１０ｋｇ／ｃｍ２ 位までで十分で
ある。[0035] The higher the pressurizing pressure, the more desirable. The greater the pressure, the faster the reaction. However, considering the required performance for pressure resistance of the pressurized tank, up to about 10 kg/cm2 is sufficient.
【００３６】加圧時間は原液組成により変るが、一般的
には１０時間位までで十分である。The pressurizing time varies depending on the composition of the stock solution, but generally up to about 10 hours is sufficient.
【００３７】また加圧時に加熱してもよい。加熱する温
度は使用する樹脂の特性によるが、たとえばポリビニル
アルコ−ルの場合９０℃までである。[0037] Furthermore, heating may be performed during pressurization. The heating temperature depends on the characteristics of the resin used; for example, in the case of polyvinyl alcohol, it is up to 90°C.
【００３８】凝固液滴を熟成する際、粒子の積み重なり
状態による凝固液滴の破損が懸念される場合には、加圧
している容器を揺動あるいは回転させることにより、凝
固液滴を流動状態に置くことも好ましい。When ripening the solidified droplets, if there is a concern that the solidified droplets may be damaged due to the stacked state of the particles, the solidified droplets may be brought into a fluid state by shaking or rotating the pressurized container. It is also preferable to put
【００３９】本発明においては、このように凝固液滴を
加圧状態の下に熟成すると、凝固が促進される。何故に
凝固が促進されるのかの理論的な解明は未だなされては
いないが、例えば、ポリビニルアルコール樹脂を含有す
るウラン原液では、硝酸ウラニルがアンモニアとの接触
により重ウラン酸アンモンになると共に多量のウラン金
属塩の存在によりポリビニルアルコール樹脂が凝固して
、凝固液滴が形成される。この凝固液滴を加圧状態の下
に熟成すると、凝固したポリビニルアルコール樹脂およ
び重ウラン酸アンモン中でのアンモニア分子の拡散が速
められることから、凝固が促進されると推定される。In the present invention, solidification is promoted by ripening the solidified droplets under pressure in this manner. Theoretical explanation of why coagulation is promoted has not yet been made, but for example, in a uranium stock solution containing polyvinyl alcohol resin, uranyl nitrate becomes ammonium deuterate upon contact with ammonia, and a large amount of The presence of the uranium metal salt causes the polyvinyl alcohol resin to coagulate, forming coagulated droplets. When these coagulated droplets are aged under pressurized conditions, the diffusion of ammonia molecules in the coagulated polyvinyl alcohol resin and ammonium deuterate is accelerated, so it is presumed that coagulation is promoted.
【００４０】上述した製造方法により得られた凝固粒子
は、内部に水分を含有しているので、更に純水等で洗浄
した後、乾燥し、焙焼、焼結を行ない球状核燃料粒子と
した後、球状核燃料粒子の表面に、熱分解炭素及び炭化
硅素等のセラミックスを蒸着被覆し、核***で生じる生
成物を閉じ込める特性を付与して高温ガス炉用被覆核燃
料粒子にすることができる。この被覆燃料粒子は、黒鉛
マトリックスに埋め込まれ、円筒状若しくは球状の黒鉛
コンポジット成型体に成型されて高温ガス型原子炉用燃
料として使用される。Since the coagulated particles obtained by the above-mentioned production method contain moisture inside, they are further washed with pure water, dried, roasted, and sintered to form spherical nuclear fuel particles. The surface of spherical nuclear fuel particles can be coated with ceramics such as pyrolytic carbon and silicon carbide by vapor deposition to impart properties that trap products generated by nuclear fission, thereby making coated nuclear fuel particles for high-temperature gas reactors. The coated fuel particles are embedded in a graphite matrix, formed into a cylindrical or spherical graphite composite molded body, and used as a fuel for a high-temperature gas nuclear reactor.
【００４１】[0041]
【実施例】以下、実施例により本発明を更に具体的に説
明するが、本発明は、これらの実施例に限定されるもの
ではない。[Examples] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.
【００４２】（実施例１）ウラン濃度２００ｇＵ／リッ
トル、ＰＶＡ樹脂３０ｇＵ／リットルおよび４ＨＦ１０
ｖ／ｏからなる硝酸性の原液を調製した。この原液を、
１００ヘルツの振動を与えながら適下ノズルよりアンモ
ニア飽和水溶液から成る凝固液中に滴下した。なお、滴
下ノズルの先端部から凝固液面迄の距離は２０ｃｍであ
った。更に、凝固液に液滴が着水するまでの空間には５
リットル／ｍｉｎの流量でアンモニアガスを流した。こ
のようにして、約５０ｇＵのＡＤＵ（重ウラン酸アンモ
ン）粒子が形成される迄滴下を継続した。(Example 1) Uranium concentration 200 gU/liter, PVA resin 30 gU/liter and 4HF10
A nitric stock solution consisting of v/o was prepared. This stock solution,
It was dropped into a coagulation liquid consisting of an ammonia saturated aqueous solution from a dropper nozzle while applying vibrations of 100 Hz. Note that the distance from the tip of the dropping nozzle to the surface of the solidified liquid was 20 cm. Furthermore, in the space before the droplet lands on the coagulation liquid, there are 5
Ammonia gas was flowed at a flow rate of liter/min. Dripping was continued in this manner until approximately 50 gU of ADU (ammonium deuterate) particles were formed.
【００４３】次に、容量５００ｃｃのオ−トクレ−ブに
２００ｃｃの２８％アンモニア水溶液を入れ、このオー
トクレーブ内に、捕集した前記ＡＤＵ粒子を移し替え、
アンモニアガスを５ｋｇ／ｃｍ２ になる迄まで加圧充
填し、オートクレーブを密封した。オ−トクレ−ブを８
０℃まで加熱し、５時間静置することにより熟成を行っ
た。Next, 200 cc of 28% ammonia aqueous solution was placed in an autoclave with a capacity of 500 cc, and the collected ADU particles were transferred into this autoclave.
Ammonia gas was filled under pressure to 5 kg/cm2, and the autoclave was sealed. Autoclave 8
Aging was performed by heating to 0° C. and allowing it to stand for 5 hours.
【００４４】熟成後、オートクレーブ内の凝固粒子を取
り出してこれを乾燥し、４５０℃の空気中で焙焼後、１
６００℃のＨ２ ガス中で還元・焼成を行ない、平均径
６００μの燃料粒子を得た。After aging, the coagulated particles in the autoclave are taken out, dried, and roasted in air at 450°C.
Reduction and firing were performed in H2 gas at 600°C to obtain fuel particles with an average diameter of 600μ.
【００４５】得られたＵＯ２ 燃料粒子は真球度もよく
（平均真球度は１、０６）、１０００個の粒子の金相観
察の結果、割れや欠けのある欠陥部を有する粒子は存在
しなかった。The obtained UO2 fuel particles had good sphericity (average sphericity was 1.06), and as a result of observing the metal phase of 1000 particles, there were no particles with defects such as cracks or chips. There wasn't.
【００４６】（比較例１）実施例１においてＡＤＵ粒子
の滴下までは実施例１と同じ工程で行なった。(Comparative Example 1) The same steps as in Example 1 were followed up to the dropping of ADU particles.
【００４７】その後、同一の凝固槽中に常圧のまま１５
時間保持した。この場合ＡＤＵ粒子が５０ｇＵと少ない
ため、重なりによるつぶれ防止のための撹拌は行なわな
かった。[0047] After that, it was left in the same coagulation tank for 15 minutes at normal pressure.
Holds time. In this case, since the ADU particles were as small as 50 gU, stirring was not performed to prevent crushing due to overlapping.
【００４８】その後、実施例１と同様に乾燥、焙焼、焼
成を実施し、ＵＯ２ 粒子を得た。[0048] Thereafter, drying, roasting, and calcination were carried out in the same manner as in Example 1 to obtain UO2 particles.
【００４９】得られた粒子のうちの１０００粒子を観察
した結果、約５０個の粒子に部分的な割れなどの欠陥が
見られた。As a result of observing 1000 of the obtained particles, defects such as partial cracks were observed in about 50 particles.
【００５０】[0050]
【発明の効果】この発明により、真球度、粒径の均一性
の良好な、かつ欠陥のない燃料核粒子が得られる。[Effects of the Invention] According to the present invention, fuel core particles having good sphericity and uniformity in particle size and having no defects can be obtained.
【００５１】この発明の方法により得られる燃料各粒子
を用いると、熱分解炭素及び炭化硅素等のセラミックス
を均一に被覆してなる被覆燃料粒子が得られ、また被覆
燃料粒子の強度も高められるので、最終的な燃料コンパ
クトでの特性が良好になる。By using the fuel particles obtained by the method of the present invention, coated fuel particles uniformly coated with ceramics such as pyrolytic carbon and silicon carbide can be obtained, and the strength of the coated fuel particles can also be increased. , the properties of the final fuel compact will be better.
【００５２】[0052]
Claims (2)
インダー樹脂等の添加剤を加えてなる原液を、アンモニ
ア水溶液中に滴下し、アンモニア水浴中で形成される凝
固液滴を加圧条件下で熟成することを特徴とする球状核
燃料粒子の製造方法。Claim 1: A stock solution prepared by dissolving a uranium compound in nitric acid and adding additives such as a binder resin is dropped into an ammonia aqueous solution, and the solidified droplets formed in an ammonia water bath are aged under pressurized conditions. A method for producing spherical nuclear fuel particles, characterized by:
としてポリビニルアルコール樹脂あるいはアルカリ条件
下で凝固する性質を有する樹脂を用いることを特徴とす
る前記請求項１に記載の球状核燃料粒子の製造方法。2. The method for producing spherical nuclear fuel particles according to claim 1, wherein a polyvinyl alcohol resin or a resin having a property of coagulating under alkaline conditions is used as the binder resin according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3066621A JPH04301595A (en) | 1991-03-29 | 1991-03-29 | Manufacture of spherical nuclear fuel particle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3066621A JPH04301595A (en) | 1991-03-29 | 1991-03-29 | Manufacture of spherical nuclear fuel particle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04301595A true JPH04301595A (en) | 1992-10-26 |
Family
ID=13321146
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3066621A Withdrawn JPH04301595A (en) | 1991-03-29 | 1991-03-29 | Manufacture of spherical nuclear fuel particle |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04301595A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006052108A (en) * | 2004-08-11 | 2006-02-23 | Nuclear Fuel Ind Ltd | Method for producing fuel particles for high-temperature gas-cooled reactor |
| RU2496162C2 (en) * | 2008-12-01 | 2013-10-20 | Нукем Текнолоджиз Гмбх | Method of and device for fuel particle production |
-
1991
- 1991-03-29 JP JP3066621A patent/JPH04301595A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006052108A (en) * | 2004-08-11 | 2006-02-23 | Nuclear Fuel Ind Ltd | Method for producing fuel particles for high-temperature gas-cooled reactor |
| JP4540047B2 (en) * | 2004-08-11 | 2010-09-08 | 原子燃料工業株式会社 | Method for producing fuel particles for HTGR |
| RU2496162C2 (en) * | 2008-12-01 | 2013-10-20 | Нукем Текнолоджиз Гмбх | Method of and device for fuel particle production |
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