JP2006045405A - Method for preparing polymer solution for stock solution containing uranyl nitrate for dripping - Google Patents

Method for preparing polymer solution for stock solution containing uranyl nitrate for dripping Download PDF

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JP2006045405A
JP2006045405A JP2004230481A JP2004230481A JP2006045405A JP 2006045405 A JP2006045405 A JP 2006045405A JP 2004230481 A JP2004230481 A JP 2004230481A JP 2004230481 A JP2004230481 A JP 2004230481A JP 2006045405 A JP2006045405 A JP 2006045405A
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uranyl nitrate
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JP4679094B2 (en
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Masashi Takahashi
昌史 高橋
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Nuclear Fuel Industries Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparing polymer solution for stock solution containing uranyl nitrate for dripping capable of preparing the polymer solution having a predetermined viscosity, homogeneity of solution, and finally providing ammonium diuranate particles with good sphericity and good inner texture. <P>SOLUTION: The invention relates to the method for preparing polymer solution for stock solution containing uranyl nitrate for dripping wherein the solution is obtained by mixing a water soluble polymer with water and preparing the aqueous solution of the water soluble polymer and then mixing the aqueous solution of the water soluble polymer with a water soluble cyclic ether. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、硝酸ウラニル含有滴下原液用ポリマー溶液調製方法に関し、さらに詳しくは、内部組織の良好な重ウラン酸アンモニウム粒子を形成することのできる硝酸ウラニル含有滴下原液を得ることのできる粘度の良好な硝酸ウラニル含有滴下原液用ポリマー溶液調製方法に関する。   The present invention relates to a method for preparing a polymer solution for a uranyl nitrate-containing dripping stock solution. More specifically, the present invention relates to a method for preparing a uranyl nitrate-containing dripping stock solution capable of forming ammonium biuranate particles having a good internal structure. The present invention relates to a method for preparing a polymer solution for a dripping stock solution containing uranyl nitrate.

高温ガス炉は、高温ガス炉用燃料を投入する炉心構造を熱容量が大きく、高温健全性の良好な黒鉛で構成している。この高温ガス炉においては、冷却ガスとして高温下でも化学反応の起こらないヘリウムガス等の気体を用いることにより、安全性を確保しているため、出口温度が高い場合でも冷却ガスを取り出すことが可能となっている。そのため、炉心において約９００℃くらいまで上昇しても、発電はもちろん水素製造や化学プラント等、幅広い分野での安全な熱利用を可能にしている。   In the high temperature gas reactor, the core structure into which the fuel for the high temperature gas reactor is charged is made of graphite having a large heat capacity and good high-temperature soundness. In this high temperature gas furnace, safety is ensured by using a gas such as helium gas that does not cause a chemical reaction even at high temperatures as the cooling gas, so the cooling gas can be taken out even when the outlet temperature is high. It has become. For this reason, even if the temperature rises to about 900 ° C. in the core, it is possible to use heat safely in a wide range of fields such as hydrogen production and chemical plants as well as power generation.

一方、この高温ガス炉に投入される高温ガス炉用燃料は、一般的に、燃料核と、この燃料核の周囲に被覆された被覆層とを備えて成る。燃料核は、例えば、二酸化ウランをセラミックス状に焼結してなる直径約３５０〜６５０μｍの微小粒子である。   On the other hand, the fuel for a HTGR to be charged into the HTGR generally includes a fuel nucleus and a coating layer coated around the fuel nucleus. The fuel core is, for example, fine particles having a diameter of about 350 to 650 μm formed by sintering uranium dioxide into a ceramic form.

被覆層は、４層構造を有し、燃料核表面側より、第一層、第二層、第三層、および第四層とを備えて成る。被覆層を構成する被覆粒子の直径は、例えば、約５００〜１０００μｍである。   The coating layer has a four-layer structure, and includes a first layer, a second layer, a third layer, and a fourth layer from the fuel core surface side. The diameter of the coated particles constituting the coating layer is, for example, about 500 to 1000 μm.

第一層は、密度が約１ｇ/ｃｍ３の低密度熱分解炭素からなり、ガス状の核分裂生成物（以下、「ＦＰ」と略す場合がある。）のガス溜めとしての機能および燃料核のスウェリングを吸収するバッファとしての機能を有するものである。第二層は、密度が約１．８ｇ/ｃｍ３の高密度熱分解炭素からなり、ガス状ＦＰの保持する機能を有するものである。 The first layer is made of low-density pyrolytic carbon having a density of about 1 g / cm 3 , functions as a gas reservoir for gaseous fission products (hereinafter sometimes referred to as “FP”), and the fuel nucleus. It has a function as a buffer that absorbs swelling. The second layer is made of high-density pyrolytic carbon having a density of about 1.8 g / cm 3 and has a function of holding the gaseous FP.

第三層は、密度が約３．２ｇ/ｃｍ３の炭素珪素（以下、「SiC」と略す場合がある。）からなり、固体ＦＰの保持する機能を有するものであり、被覆層の主要な強度材である。第四層は、第二層と同様の密度が約１．８ｇ/ｃｍ３の高密度熱分解炭素からなり、ガス状ＦＰの保持する機能を有するとともに、第三層の保護層としての機能を有するものである。 The third layer is made of carbon silicon having a density of about 3.2 g / cm 3 (hereinafter sometimes abbreviated as “SiC”) and has a function to be held by the solid FP. It is a strength material. The fourth layer is made of high-density pyrolytic carbon having a density of about 1.8 g / cm 3 similar to that of the second layer, and has a function of holding the gaseous FP and also functions as a protective layer of the third layer. It is what you have.

以上のような高温ガス炉用燃料は、一般的に以下のような工程を経て製造される。まず、酸化ウランの粉末を硝酸に溶かし硝酸ウラニル原液とする。次に、この硝酸ウラニル原液に純水、増粘剤、例えば、ＰＶＡ溶液を添加し、攪拌して滴下原液とする。調製された滴下原液は、所定の温度に冷却され粘度を調製後、細径の滴下ノズルを用いてアンモニア水溶液に滴下される。   The HTGR fuel as described above is generally manufactured through the following steps. First, uranium oxide powder is dissolved in nitric acid to obtain a uranyl nitrate stock solution. Next, pure water and a thickener such as a PVA solution are added to the uranyl nitrate stock solution and stirred to obtain a dripping stock solution. The prepared dripping stock solution is cooled to a predetermined temperature to adjust the viscosity, and then dropped into an aqueous ammonia solution using a small-diameter dropping nozzle.

このアンモニア水溶液に滴下された液滴は、アンモニア水溶液表面に達するまでの間に、アンモニアガスを吹きかけられる。このアンモニアガスによって、液滴表面をゲル化させるため、アンモニア水溶液表面到達時における変形を防止することができる。アンモニア水溶液中における硝酸ウラニルは、アンモニアと十分に反応し、重ウラン酸アンモニウム粒子（以下、「ＡＤＵ粒子」と略す場合がある。）となる。   The droplets dropped on the aqueous ammonia solution are sprayed with ammonia gas before reaching the surface of the aqueous ammonia solution. Since the droplet surface is gelled by this ammonia gas, it is possible to prevent deformation when reaching the surface of the aqueous ammonia solution. Uranyl nitrate in the aqueous ammonia solution sufficiently reacts with ammonia to form ammonium heavy uranate particles (hereinafter sometimes referred to as “ADU particles”).

この重ウラン酸アンモニウム粒子は、乾燥された後、大気中で焙焼され、三酸化ウラン粒子となる。さらに、三酸化ウラン粒子は、還元・焼結されることにより、高密度のセラミック状の二酸化ウラン粒子となる。この二酸化ウラン粒子をふるい分け、すなわち分級して、所定の粒子径を有する燃料核微粒子を得る。   The ammonium heavy uranate particles are dried and then baked in the air to form uranium trioxide particles. Further, the uranium trioxide particles are reduced and sintered to become high-density ceramic uranium dioxide particles. The uranium dioxide particles are screened, that is, classified to obtain fuel core fine particles having a predetermined particle size.

この燃料核微粒子を流動床に装荷し、被覆層を形成するためのガスを熱分解して、燃料核微粒子表面に被覆層を形成する。被覆層の第一層の低密度熱分解炭素の場合は、約１３００℃でアセチレンを熱分解する。また、被覆層の第二層、第四層の高密度熱分解炭素の場合は、約１４００℃でプロピレンを熱分解する。さらに、被覆層の第三層のSiCの場合は、約１５００℃でメチルトリクロロシランを熱分解する。   The fuel core fine particles are loaded onto the fluidized bed, and the gas for forming the coating layer is pyrolyzed to form the coating layer on the surface of the fuel core fine particles. In the case of the low-density pyrolytic carbon of the first layer of the coating layer, acetylene is pyrolyzed at about 1300 ° C. In the case of the high density pyrolytic carbon of the second layer and the fourth layer of the coating layer, propylene is pyrolyzed at about 1400 ° C. Further, in the case of SiC as the third layer of the coating layer, methyltrichlorosilane is thermally decomposed at about 1500 ° C.

被覆層が形成された後、高温ガス炉用燃料は、一般的な燃料コンパクトとして成型される。この燃料コンパクトは、高温ガス炉用燃料を黒鉛粉末、粘結剤等からなる黒鉛マトリックス材とともに、中空円筒形等にプレス成型またはモールド成型したのち、焼成して得られる(非特許文献１および２参照)。   After the coating layer is formed, the HTGR fuel is molded as a general fuel compact. This fuel compact is obtained by press-molding or molding a HTGR fuel into a hollow cylindrical shape together with a graphite matrix material made of graphite powder, a binder, etc., and then firing (Non-Patent Documents 1 and 2). reference).

原子炉材料ハンドブック ｐ２２１〜２４０、昭和５２年１０月３１日発行、日刊工業新聞社発行Reactor Material Handbook p221-240, published October 31, 1977, published by Nikkan Kogyo Shimbun 原子力ハンドブック、ｐ１６１−ｐ１６９、平成７年１２月２０日発行、株式会社オーム社Nuclear Handbook, p161-p169, issued on December 20, 1995, Ohm Corporation

しかしながら、重ウラン酸アンモニウム粒子を製造する際に、硝酸ウラニルと水と増粘剤とをそれぞれ所定の割合と成るようにそれぞれ秤量し、前記三成分を同時に、或いは順次に混合するだけでは、所定粘度の、均一な溶液であり、しかも真球度が良好であり、内部組織の良好な重ウラン酸アンモニウム粒子を最終的に得ることのできる硝酸ウラニル含有滴下原液用ポリマー用溶液を調製することができなかった。   However, when producing ammonium biuranium particles, uranyl nitrate, water, and thickener are weighed in a predetermined ratio, and the above three components are mixed simultaneously or sequentially. It is possible to prepare a solution for a polymer for dripping stock solution containing uranyl nitrate, which is a uniform solution with viscosity and good sphericity, and can finally obtain ammonium heavy uranate particles having a good internal structure. could not.

本発明は、このような従来の問題点を解消し、所定粘度の、均一な溶液であり、しかも真球度が良好であり、内部組織の良好な重ウラン酸アンモニウム粒子を最終的に得ることのできる硝酸ウラニル含有滴下原液用ポリマー用溶液を調製することができる硝酸ウラニル含有滴下原液用ポリマー溶液の調製方法を提供することを、その課題とする。   The present invention eliminates such conventional problems, and finally obtains ammonium biuranate particles having a uniform viscosity, a uniform solution, good sphericity, and good internal structure. An object of the present invention is to provide a method for preparing a polymer solution for a uranyl nitrate-containing dripping stock solution capable of preparing a uranyl nitrate-containing polymer solution for a dripping stock solution.

上記課題を解決するための手段として、
請求項１は、水溶性ポリマーと水とを混合して、６〜９質量％の水溶性ポリマー水溶液を調製し、前記水溶性ポリマー水溶液と水溶性環状エーテルとを混合することを特徴とする硝酸ウラニル含有滴下原液用ポリマー溶液調製方法であり、
請求項２は、前記水溶性ポリマーと水とを、低くても７５℃に加熱しながら混合することを特徴とする前記請求項１に記載の硝酸ウラニル含有滴下原液用ポリマー溶液調製方法であり、
請求項３は、前記硝酸ウラニル含有滴下原液に含まれる水溶性環状エーテルの含有量の１〜５０体積％に相当する水溶性環状エーテルと前記水溶性ポリマー水溶液とを、低くとも５０℃以上で混合することを特徴とする前記請求項１または請求項２に記載の硝酸ウラニル含有滴下原液用ポリマー溶液調製方法である。 As means for solving the above problems,
Claim 1 is a nitric acid characterized in that a water-soluble polymer and water are mixed to prepare a 6-9 mass% water-soluble polymer aqueous solution, and the water-soluble polymer aqueous solution and a water-soluble cyclic ether are mixed. It is a polymer solution preparation method for uranyl-containing dripping stock solution,
The method for preparing a polymer solution for a uranyl nitrate-containing dripping stock solution according to claim 1, wherein the water-soluble polymer and water are mixed while being heated to at least 75 ° C.
In claim 3, the water-soluble cyclic ether corresponding to 1 to 50% by volume of the content of the water-soluble cyclic ether contained in the uranyl nitrate-containing dropping stock solution and the water-soluble polymer aqueous solution are mixed at 50 ° C or more at least The method for preparing a polymer solution for a uranyl nitrate-containing dripping stock solution according to claim 1 or 2, wherein:

本発明によれば、水溶性ポリマーの溶解残渣が発生することがなく、かつ、所定粘度の硝酸ウラニル含有滴下原液用ポリマー溶液を得ることができる。   ADVANTAGE OF THE INVENTION According to this invention, the melt | dissolution residue of a water-soluble polymer does not generate | occur | produce, and the polymer solution for dripping stock solutions containing uranyl nitrate of predetermined viscosity can be obtained.

水溶性ポリマーと水とを混合するに際し、低くとも７５℃に加熱するので、水溶性ポリマーの水への溶解が円滑に行われ、水溶性ポリマーの固形分残渣を生じることがない。   When mixing the water-soluble polymer and water, the water-soluble polymer is heated to at least 75 ° C., so that the water-soluble polymer is smoothly dissolved in water and no solid residue of the water-soluble polymer is produced.

前記硝酸ウラニル含有滴下原液に含まれる水溶性環状エーテルの含有量に対して所定量の水溶性環状エーテルと前記水溶性ポリマー水溶液とを所定温度下で混合するので、水溶性ポリマーの皮膜が混合液の表面に生じることがなく、内部組織の良好な重ウラン酸アンモニウム粒子を形成することのできる所定粘度の硝酸ウラニル含有滴下原液を調製することができる。   Since a predetermined amount of the water-soluble cyclic ether and the water-soluble polymer aqueous solution are mixed at a predetermined temperature with respect to the content of the water-soluble cyclic ether contained in the uranyl nitrate-containing stock solution, the water-soluble polymer film is a mixed solution. Thus, a uranyl nitrate-containing dropping stock solution having a predetermined viscosity capable of forming ammonium heavy uranate particles having a good internal structure can be prepared.

本発明の硝酸ウラニル含有滴下原液用ポリマー溶液調製方法は、水溶性ポリマー水溶液を調製する水溶性ポリマー水溶液調製工程と、硝酸ウラニル含有滴下原液用ポリマー溶液調製工程とを含む。   The method for preparing a polymer solution for a uranyl nitrate-containing dropping stock solution of the present invention includes a water-soluble polymer aqueous solution preparing step for preparing a water-soluble polymer aqueous solution and a polymer solution preparing step for a uranyl nitrate-containing dropping stock solution.

［水溶性ポリマー水溶液調製工程］
本発明における水溶性ポリマー水溶液調製工程は、水溶性ポリマーと水とを加熱しながら混合して水溶性ポリマー水溶液を得る操作を含む。 [Water-soluble polymer aqueous solution preparation process]
The water-soluble polymer aqueous solution preparation step in the present invention includes an operation of mixing a water-soluble polymer and water while heating to obtain a water-soluble polymer aqueous solution.

前記水溶性ポリマーとしては、ポリビニルアルコール（以下、ＰＶＡと略する。）、ポリアクリル酸ナトリウム及びポリエチレンオキシド等の合成ポリマー、カルボキシメチルセルロース、ヒドロキシエチルセルロース、メチルセルロース、及びエチルセルロース等のセルロース系ポリマー、可溶性でんぷん、及びカルボキシメチルでんぷん等のでんぷん系ポリマー、デキストリン、及びガラクタン等の水溶性天然高分子等を挙げることができる。   Examples of the water-soluble polymer include polyvinyl alcohol (hereinafter abbreviated as PVA), synthetic polymers such as sodium polyacrylate and polyethylene oxide, cellulose polymers such as carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, and ethyl cellulose, soluble starch, And starch-based polymers such as carboxymethyl starch, water-soluble natural polymers such as dextrin, and galactan.

これら各種の水溶性ポリマーは、その一種を単独で使用されても、また、それらの二種以上が併用されていても良い。これらの中でも、水溶性ポリマーとして前記合成ポリマーが好ましく、特にポリビニルアルコールが好ましい。   One of these various water-soluble polymers may be used alone, or two or more thereof may be used in combination. Among these, the synthetic polymer is preferable as the water-soluble polymer, and polyvinyl alcohol is particularly preferable.

前記水溶性ポリマー、例えば、ＰＶＡの形態については、特に制限はなく、粉末状であっても、顆粒状であってもよい。   There is no restriction | limiting in particular about the form of the said water-soluble polymer, for example, PVA, A powder form or a granular form may be sufficient.

前記水溶性ポリマーの水溶性ポリマー水溶液における含有割合としては、通常、６〜９質量％であり、特に、７〜８質量％が好ましい。前記水溶性ポリマーの水溶性ポリマー水溶液における含有割合が前記範囲内にあると、硝酸ウラニル含有滴下原液の粘度を、０．０４〜０．０６Ｐａ・ｓの範囲内に良好に維持することができ、さらに、水溶性ポリマー水溶液、例えば、ポリビニルアルコール水溶液（以下、ＰＶＡ水溶液と略する。）中にＰＶＡ等の水溶性ポリマーの溶解残渣が生じることがない。   As a content rate in the water-soluble polymer aqueous solution of the said water-soluble polymer, it is 6-9 mass% normally, and 7-8 mass% is especially preferable. When the content ratio of the water-soluble polymer in the water-soluble polymer aqueous solution is within the above range, the viscosity of the uranyl nitrate-containing dropping stock solution can be well maintained within the range of 0.04 to 0.06 Pa · s, Further, a water-soluble polymer aqueous solution, for example, a polyvinyl alcohol aqueous solution (hereinafter abbreviated as PVA aqueous solution) does not cause a residue of water-soluble polymer such as PVA.

前記水溶性ポリマーの水溶性ポリマー水溶液における含有割合が６質量％未満であると、最終的に得られる硝酸ウラニル含有滴下原液の粘度が小さくなり過ぎて硝酸ウラニル含有滴下原液の滴下に支障を来たし、９質量％を超えると水溶性ポリマー水溶液に水溶性ポリマーの溶解残渣を生じてしまう。   When the content ratio of the water-soluble polymer in the water-soluble polymer aqueous solution is less than 6% by mass, the viscosity of the finally obtained uranyl nitrate-containing dripping stock solution becomes too small, which hinders the dripping of the uranyl nitrate-containing dripping stock solution, When it exceeds 9 mass%, the melt | dissolution residue of a water-soluble polymer will be produced in water-soluble polymer aqueous solution.

前記混合に際する加熱温度つまり水溶性ポリマーと水との混合物を加熱する温度は、低くとも７５℃つまり７５℃以上であるのが好ましい。前記加熱温度が７５℃以上であれば、水溶性ポリマーの未溶解残渣がなく、均一な水溶性ポリマー水溶液を調製することができる。   The heating temperature for the mixing, that is, the temperature for heating the mixture of the water-soluble polymer and water, is preferably at least 75 ° C., that is, 75 ° C. or higher. When the heating temperature is 75 ° C. or higher, there is no undissolved residue of the water-soluble polymer, and a uniform water-soluble polymer aqueous solution can be prepared.

水溶性ポリマーと水との混合物は通常、攪拌される。攪拌時間は、通常、８０〜１００分であるのが好ましい。加熱しながら前記混合物を攪拌混合すると、水が蒸発して混合物中の水分の含有量が低下することがあるが、減少した水分量は、加熱されている混合物に適宜に水を添加することにより、補われる。   The mixture of water-soluble polymer and water is usually stirred. The stirring time is usually preferably 80 to 100 minutes. When the mixture is stirred and mixed while heating, water may evaporate and the water content in the mixture may decrease. The reduced water content can be reduced by adding water to the heated mixture as appropriate. To be compensated.

［硝酸ウラニル含有滴下原液用ポリマー溶液調製工程］
本発明における硝酸ウラニル含有滴下原液用ポリマー溶液調製工程は、前記水溶性ポリマー水溶液と水溶性環状エーテルとを混合する操作を含む。この硝酸ウラニル含有滴下原液用ポリマー溶液を調製する際に水溶性環状エーテルを混合するのは、水溶性環状エーテルが系中に存在しない場合には、水溶性ポリマー水溶液の温度が低下すると、水溶性ポリマー水溶液の表面に水溶性ポリマーの皮膜が形成されてしまい、水溶性ポリマー水溶液の均一な溶解状態が維持されなくなってしまうのであるが、水溶性環状エーテルが系中に存在すると、硝酸ウラニル含有滴下原液用ポリマー溶液の均一な溶液状態を実現することができる。 [Process for preparing polymer solution for dripping stock solution containing uranyl nitrate]
The polymer solution preparation step for the uranyl nitrate-containing dropping stock solution in the present invention includes an operation of mixing the water-soluble polymer aqueous solution and the water-soluble cyclic ether. The water-soluble cyclic ether is mixed when preparing the polymer solution for uranyl nitrate-containing dripping stock solution when the temperature of the water-soluble polymer aqueous solution decreases when the water-soluble cyclic ether does not exist in the system. A water-soluble polymer film is formed on the surface of the polymer aqueous solution, and the uniform dissolution state of the water-soluble polymer aqueous solution is not maintained. However, when water-soluble cyclic ether is present in the system, dripping with uranyl nitrate is included. A uniform solution state of the polymer solution for the stock solution can be realized.

前記水溶性環状エーテルとしては、テトラヒドロフルフリルアルコール（以下、ＴＨＦＡと略する。）、オキセタン、テトラヒドロフラン、及びジオキサン等の炭素数１〜４の水溶性環状エーテル、並びに２，５−テトラヒドロフランジメタノール等の、炭素数が１〜３のアルカノール基を前記環状エーテルに結合するアルカノール基含有水溶性環状エーテル等を挙げることができる。   Examples of the water-soluble cyclic ether include water-soluble cyclic ethers having 1 to 4 carbon atoms such as tetrahydrofurfuryl alcohol (hereinafter abbreviated as THFA), oxetane, tetrahydrofuran, and dioxane, and 2,5-tetrahydrofuran dimethanol. The alkanol group containing water-soluble cyclic ether which couple | bonds the C1-C3 alkanol group with the said cyclic ether can be mentioned.

これら各種の水溶性環状エーテルは、その一種を単独で前記水溶性ポリマー水溶液に添加することができ、また、それらの二種以上を前記水溶性ポリマー水溶液に添加することもできる。この発明において好ましい水溶性環状エーテルとしては、テトラヒドロフラン、ジオキサン、ＴＨＦＡ及び２，５−テトラヒドロフランジメタノール等の水溶性環状エーテルを挙げることができる。   One of these various water-soluble cyclic ethers can be added alone to the water-soluble polymer aqueous solution, or two or more of them can be added to the water-soluble polymer aqueous solution. Preferred water-soluble cyclic ethers in the present invention include water-soluble cyclic ethers such as tetrahydrofuran, dioxane, THFA, and 2,5-tetrahydrofuran dimethanol.

前記水溶性環状エーテルと前記水溶性ポリマー水溶液との混合割合は、硝酸ウラニル含有滴下原液を調製する際の前記水溶性ポリマー水溶液が硝酸ウラニル滴下原液全体の１５〜２０体積％となる水溶性ポリマー水溶液の量に対し、前記水溶性環状エーテルの配合量が、硝酸ウラニル含有滴下原液中の前記水溶性環状エーテルの全量に対して１〜５０体積％、特に３０〜４０体積％となるように、調整される。   The mixing ratio of the water-soluble cyclic ether and the water-soluble polymer aqueous solution is such that the water-soluble polymer aqueous solution in preparing the uranyl nitrate-containing dropping stock solution is 15 to 20% by volume of the whole uranyl nitrate dropping stock solution. The amount of the water-soluble cyclic ether is adjusted to 1 to 50% by volume, particularly 30 to 40% by volume, based on the total amount of the water-soluble cyclic ether in the uranyl nitrate-containing dropping stock solution. Is done.

前記水溶性環状エーテルの配合量が前記範囲内にあると、硝酸ウラニル含有滴下原液用ポリマー溶液の温度が下がっても、この硝酸ウラニル含有滴下原液用ポリマー溶液の表面に、水溶性ポリマーの皮膜が形成されることがなく、したがって、水溶性ポリマーが均一に分散した硝酸ウラニル含有滴下原液用ポリマー溶液を得ることができる。   When the blending amount of the water-soluble cyclic ether is within the above range, a water-soluble polymer film is formed on the surface of the uranyl nitrate-containing dropping stock solution polymer solution even when the temperature of the uranyl nitrate-containing dropping stock solution polymer solution is lowered. Thus, a uranyl nitrate-containing polymer solution for dripping stock solution in which the water-soluble polymer is uniformly dispersed can be obtained.

また、前記水溶性環状エーテルと前記水溶性ポリマー水溶液とを混合する際には、それら混合物の温度を低くても５０℃、好ましくは、低くても６０℃になる前に、水溶性環状エーテル、例えば、ＴＨＦＡを攪拌、混合しながら、添加するのが好ましい。   Further, when mixing the water-soluble cyclic ether and the water-soluble polymer aqueous solution, the temperature of the mixture is at least 50 ° C., preferably at least 60 ° C. before the water-soluble cyclic ether, For example, it is preferable to add THFA while stirring and mixing.

前記水溶性ポリマー水溶液の温度が、５０℃未満になってから、水溶性環状エーテル、例えば、ＴＨＦＡを添加すると、水溶性ポリマー溶液中の水溶性ポリマーがゲル化してしまい、その結果、滴下原液を滴下するときに不都合を生じることがある。   When a water-soluble cyclic ether such as THFA is added after the temperature of the water-soluble polymer aqueous solution is less than 50 ° C., the water-soluble polymer in the water-soluble polymer solution is gelled. There may be inconveniences when dripping.

前記水溶性ポリマー水溶液と前記水溶性環状エーテルとを混合することにより硝酸ウラニル含有滴下原液用ポリマー溶液を得ることができる。   By mixing the water-soluble polymer aqueous solution and the water-soluble cyclic ether, a polymer solution for dripping stock solution containing uranyl nitrate can be obtained.

［硝酸ウラニル含有滴下原液調製工程］
本発明に係る硝酸ウラニル含有滴下原液用ポリマー溶液は、さらに硝酸ウラニルと水溶性環状エーテルと混合されて硝酸ウラニル含有滴下原液（以下において、単に滴下原液と称することがある。）が調製される。 [Uranyl nitrate-containing dripping stock solution preparation process]
The uranyl nitrate-containing dropping stock solution according to the present invention is further mixed with uranyl nitrate and a water-soluble cyclic ether to prepare a uranyl nitrate-containing dropping stock solution (hereinafter, sometimes simply referred to as a dropping stock solution).

前記硝酸ウラニルは、硝酸に酸化ウランを溶解することにより容易に形成することができる。前記硝酸は、硝酸水溶液の形態で通常に使用される。硝酸水溶液の濃度としては、特に制限がなく、公知の濃度でよい。硝酸ウラニルの滴下原液における含有量としては、通常、０．６〜０．９mol−Ｕ/Ｌであるのが好ましい。   The uranyl nitrate can be easily formed by dissolving uranium oxide in nitric acid. The nitric acid is usually used in the form of an aqueous nitric acid solution. There is no restriction | limiting in particular as a density | concentration of nitric acid aqueous solution, A well-known density | concentration may be sufficient. The content of uranyl nitrate in the dropping stock solution is usually preferably 0.6 to 0.9 mol-U / L.

硝酸ウラニルの含有量が前記範囲内にあると、水溶性環状エーテル及び水溶性ポリマーの共存とによって、真球度の高い二酸化ウランを良好に再現性よく製造することができ、前記範囲を外れると、真球度の低い二酸化ウランが生成することがある。   When the content of uranyl nitrate is within the above range, uranium dioxide with high sphericity can be produced with good reproducibility by the coexistence of the water-soluble cyclic ether and the water-soluble polymer. Uranium dioxide with low sphericity may be produced.

前記水溶性環状エーテルは、硝酸ウラニル含有滴下原液用ポリマー溶液を調製する際に使用される水溶性環状エーテルと同じ種類の水溶性環状エーテルであるのが好ましいが、異なる種類の水溶性環状エーテルであっても良い。   The water-soluble cyclic ether is preferably the same type of water-soluble cyclic ether as the water-soluble cyclic ether used in preparing the uranyl nitrate-containing dropping stock solution polymer solution. There may be.

硝酸ウラニル及び硝酸ウラニル含有滴下原液用ポリマー溶液と混合される水溶性環状エーテルの量は、滴下原液中の水溶性環状エーテルの含有量が４０〜５０体積％となるように、適宜に調整され、添加する。   The amount of the water-soluble cyclic ether mixed with the uranyl nitrate and uranyl nitrate-containing dropping stock solution polymer solution is appropriately adjusted so that the content of the water-soluble cyclic ether in the dropping stock solution is 40 to 50% by volume, Added.

本発明における滴下原液は、本発明の目的を阻害しない限り、その他の成分を含有することができる。   The stock solution for dripping in the present invention can contain other components as long as the object of the present invention is not impaired.

硝酸ウラニル含有滴下原液の調整においては、硝酸ウラニルと、ＴＨＦＡ等の水溶性環状エーテルとを混合し、その後、更にポリマー溶液を混合することが好ましい。   In preparing the uranyl nitrate-containing dropping stock solution, it is preferable to mix uranyl nitrate and a water-soluble cyclic ether such as THFA, and then further mix the polymer solution.

以上のようにして得られた滴下原液においては、ウランが０．６〜０．９ｍｏｌ／Ｌ、より好ましくは、０．７〜０．８ｍｏｌ／Ｌ、水溶性ポリマーが１０〜１５ｇ／Ｌ、水溶性環状エーテルが４０〜５０体積％である組成割合になるように、適宜に水を補充することなどによりその組成割合が調整される。   In the dropping stock solution obtained as described above, uranium is 0.6 to 0.9 mol / L, more preferably 0.7 to 0.8 mol / L, water-soluble polymer is 10 to 15 g / L, water-soluble The composition ratio is adjusted, for example, by supplementing water appropriately so that the composition ratio of the cyclic ether is 40 to 50% by volume.

［重ウラン酸アンモニウム粒子の製造手順］
以上のようにして調製された硝酸ウラニル含有滴下原液は、所定の温度に冷却され粘度を調製後、細径の滴下ノズルを用いてアンモニア水溶液に滴下される。 [Procedure for producing ammonium heavy uranate particles]
The uranyl nitrate-containing dropping stock solution prepared as described above is cooled to a predetermined temperature, adjusted in viscosity, and then dropped into an aqueous ammonia solution using a small-diameter dropping nozzle.

このアンモニア水溶液に滴下された液滴は、アンモニア水溶液表面に達するまでの間に、アンモニアガスを吹きかけられる。このアンモニアガスによって、液滴表面をゲル化させるため、アンモニア水溶液表面到達時のおける変形を防止することができる。アンモニア水溶液中における硝酸ウラニルは、アンモニアと十分に反応し、重ウラン酸アンモニウム粒子（ＡＤＵ粒子）となる。   The droplets dropped on the aqueous ammonia solution are sprayed with ammonia gas before reaching the surface of the aqueous ammonia solution. Since the droplet surface is gelled by this ammonia gas, it is possible to prevent deformation when reaching the surface of the aqueous ammonia solution. Uranyl nitrate in the aqueous ammonia solution sufficiently reacts with ammonia to form ammonium heavy uranate particles (ADU particles).

［燃料核の製造手順］
この重ウラン酸アンモニウム粒子は、乾燥された後、大気中で焙焼され、三酸化ウラン粒子となる。さらに、三酸化ウラン粒子は、還元・焼結されることにより、高密度のセラミック状の二酸化ウラン粒子となる。この二酸化ウラン粒子をふるい分け、すなわち分級して、所定の粒子径を有する燃料核を得る。 [Procedure for fuel core production]
The ammonium heavy uranate particles are dried and then baked in the air to form uranium trioxide particles. Further, the uranium trioxide particles are reduced and sintered to become high-density ceramic uranium dioxide particles. The uranium dioxide particles are screened, that is, classified to obtain fuel nuclei having a predetermined particle size.

［高温ガス炉用燃料］
なお、この燃料核を使用してなる高温ガス炉用燃料は、以下のような構造を有している。高温ガス炉用燃料は、燃料核と、燃料核と、この燃料核の周囲に被覆された被覆層とを備えて成る。 [Fuel for HTGR]
Note that the fuel for a high temperature gas reactor using this fuel nucleus has the following structure. The fuel for the HTGR comprises a fuel nucleus, a fuel nucleus, and a coating layer coated around the fuel nucleus.

また、被覆層は、４層構造を有し、燃料核表面側より、第一層、第二層、第三層、および第四層とを備えて成る。被覆粒子の直径は、例えば、約５００〜１０００μｍである。   The coating layer has a four-layer structure, and includes a first layer, a second layer, a third layer, and a fourth layer from the fuel core surface side. The diameter of the coated particles is, for example, about 500 to 1000 μm.

第一層は、密度が約１ｇ/ｃｍ３の低密度熱分解炭素からなり、ガス状の核分裂生成物（以下、「ＦＰ」と略す場合がある。）のガス溜めとしての機能および燃料核のスウェリングを吸収するバッファとしての機能を有するものである。 The first layer is made of low-density pyrolytic carbon having a density of about 1 g / cm 3 , functions as a gas reservoir for gaseous fission products (hereinafter sometimes referred to as “FP”), and the fuel nucleus. It has a function as a buffer that absorbs swelling.

第二層は、密度が約１．８ｇ/ｃｍ３の高密度熱分解炭素からなり、ガス状ＦＰの保持する機能を有するものである。第三層は、密度が約３．２ｇ/ｃｍ３の炭素珪素からなり、固体ＦＰの保持する機能を有するものであり、被覆層の主要な強度材である。第四層は、第二層と同様の密度が約１．８ｇ/ｃｍ３の高密度熱分解炭素からなり、ガス状ＦＰの保持する機能を有するとともに、第三層の保護層としての機能を有するものである。 The second layer is made of high-density pyrolytic carbon having a density of about 1.8 g / cm 3 and has a function of holding the gaseous FP. The third layer is made of carbon silicon having a density of about 3.2 g / cm 3 , has a function to be held by the solid FP, and is a main strength material of the coating layer. The fourth layer is made of high-density pyrolytic carbon having a density of about 1.8 g / cm 3 similar to that of the second layer, and has a function of holding the gaseous FP and also functions as a protective layer of the third layer. It is what you have.

［高温ガス炉用燃料の製造手順］
高温ガス炉用燃料の製造手順は、以下のとおりである。まず、上記のようにして得られた二酸化ウラン粒子を流動床に装荷し、被覆層を形成するためのガスを熱分解して、高温ガス炉用燃料核微粒子としての二酸化ウラン粒子表面に被覆層を形成する。被覆層の第一層の低密度熱分解炭素の場合は、約１３００℃でアセチレンを熱分解する。 [Manufacturing procedure of fuel for HTGR]
The manufacturing procedure of the HTGR fuel is as follows. First, the uranium dioxide particles obtained as described above are loaded onto a fluidized bed, the gas for forming the coating layer is pyrolyzed, and the coating layer is formed on the surface of the uranium dioxide particles as fuel core fine particles for the high temperature gas reactor. Form. In the case of the low-density pyrolytic carbon of the first layer of the coating layer, acetylene is pyrolyzed at about 1300 ° C.

また、被覆層の第二層、第四層の高密度熱分解炭素の場合は、約１４００℃でプロピレンを熱分解する。さらに、被覆層における第三層の炭素珪素の場合は、約１５００℃でメチルトリクロロシランを熱分解する。   In the case of the high density pyrolytic carbon of the second layer and the fourth layer of the coating layer, propylene is pyrolyzed at about 1400 ° C. Furthermore, in the case of the third layer of carbon silicon in the coating layer, methyltrichlorosilane is thermally decomposed at about 1500 ° C.

以上の被覆層が形成された後、高温ガス炉用燃料は、一般的な燃料コンパクトとして成型される。この燃料コンパクトは、高温ガス炉用燃料を黒鉛粉末、粘結剤等からなる黒鉛マトリックス材とともに、中空円筒形等にプレス成型またはモールド成型したのち、焼成して得られる。   After the above coating layer is formed, the HTGR fuel is molded as a general fuel compact. This fuel compact is obtained by press-molding or molding a fuel for a high-temperature gas reactor into a hollow cylinder or the like together with a graphite matrix material made of graphite powder, a binder, and the like, followed by firing.

（実施例１）
４Ｌの純水に、３００ｇのポリビニルアルコール粉末（ＰＶＡ粉末）を添加して得た混合液を、９５℃で９０分間、攪拌することにより、ＰＶＡの濃度が７質量％であるＰＶＡ水溶液を得た。このＰＶＡ水溶液は本発明における水溶性ポリマー水溶液である。次いで、このＰＶＡ水溶液を、液温が５０℃になるまで放冷した後、４Ｌのテトラヒドロフルフリルアルコール（ＴＨＦＡ）を添加して硝酸ウラニル含有滴下原液用ポリマー溶液を得た。 Example 1
By stirring a mixed solution obtained by adding 300 g of polyvinyl alcohol powder (PVA powder) to 4 L of pure water at 95 ° C. for 90 minutes, a PVA aqueous solution having a PVA concentration of 7% by mass was obtained. . This PVA aqueous solution is the water-soluble polymer aqueous solution in the present invention. Next, this PVA aqueous solution was allowed to cool until the liquid temperature reached 50 ° C., and then 4 L of tetrahydrofurfuryl alcohol (THFA) was added to obtain a polymer solution for dripping stock solution containing uranyl nitrate.

以上のようにして得られた硝酸ウラニル含有滴下原液用ポリマー溶液中に、溶解残渣は確認されなかった。   No dissolution residue was confirmed in the polymer solution for uranyl nitrate-containing dripping stock solution obtained as described above.

さらに、この硝酸ウラニル含有滴下原液用ポリマー溶液 約８Ｌに硝酸ウラニル溶液 ９ＬとＴＨＦＡ ７Ｌと適宜、純水を添加して、硝酸ウラニル含有滴下原液を得た。   Further, 9 L of uranyl nitrate solution and 7 L of THFA were appropriately added to about 8 L of the polymer solution for dripping stock solution containing uranyl nitrate to obtain a dripping stock solution containing uranyl nitrate.

また、本実施例で得られた硝酸ウラニル含有滴下原液の粘度を、粘度計（山一電機社製）を用いて測定したところ、１２℃において、０．０５５Ｐａ・ｓであった。   Further, the viscosity of the uranyl nitrate-containing dropping stock solution obtained in this example was measured by using a viscometer (manufactured by Yamaichi Electronics Co., Ltd.) and found to be 0.055 Pa · s at 12 ° C.

この滴下原液をアンモニア水中に滴下することにより重ウラン酸アンモニウム粒子を製造した。その後、乾燥工程を経た重ウラン酸アンモニウム粒子の直径面で二つに切断してその裁断面を観察したところ、均一な内部組織が形成されていることを確認した（図１参照）。また、後述する真球度の評価方法によって、燃料核の真球度の評価を行い、１％以下の不良率であることを確認した。   The dripping stock solution was dropped into ammonia water to produce ammonium heavy uranate particles. Then, when it cut | disconnected in the diameter surface of the ammonium biuranium-particles which passed through the drying process and observed the cut surface, it confirmed that the uniform internal structure | tissue was formed (refer FIG. 1). Further, the sphericity of the fuel nucleus was evaluated by a sphericity evaluation method described later, and it was confirmed that the defect rate was 1% or less.

（比較例１）
実施例におけるＰＶＡの添加量を２３０ｇに変更した以外は、実施例１と同様にして、滴下原液を得た。すなわち、ＰＶＡの濃度が５．４質量％であるＰＶＡ水溶液を使用した。 (Comparative Example 1)
A dripping stock solution was obtained in the same manner as in Example 1 except that the amount of PVA added in the example was changed to 230 g. That is, a PVA aqueous solution having a PVA concentration of 5.4% by mass was used.

また、前記滴下原液の粘度を、前記粘度計を用いて測定したところ、０．０３５Ｐａ・ｓであり、実施例１で調製した滴下原液よりも、粘度が低いことがわかった。   Moreover, when the viscosity of the said dripping stock solution was measured using the said viscometer, it was 0.035 Pa * s, and it turned out that the viscosity is lower than the dripping stock solution prepared in Example 1.

この滴下原液を用いて製造された重ウラン酸アンモニウム粒子を、乾燥した後、大気中で焙焼し、三酸化ウラン粒子とした。さらに、三酸化ウラン粒子は、還元・焼結されることにより、高密度のセラミック状の二酸化ウラン粒子とした。この二酸化ウラン粒子をふるい分け、すなわち分級して、所定の粒子径を有する燃料核（二酸化ウラン粒子）を得た。   The ammonium heavy uranate particles produced using this dropping stock solution were dried and then baked in the air to obtain uranium trioxide particles. Furthermore, the uranium trioxide particles were reduced and sintered to obtain high-density ceramic uranium dioxide particles. The uranium dioxide particles were screened, that is, classified to obtain fuel nuclei (uranium dioxide particles) having a predetermined particle size.

得られた燃料核（二酸化ウラン粒子）を以下に説明する真球度の評価方法を用いて真球度の低い燃料核（二酸化ウラン粒子）を分別したところ、７％の燃料核が不良となった。   When the obtained fuel nuclei (uranium dioxide particles) were separated from low sphericity fuel nuclei (uranium dioxide particles) using the sphericity evaluation method described below, 7% of the fuel nuclei became defective. It was.

これは、滴下原液の粘度が低いことにより、アンモニア水への着水時の衝撃が加わり、この衝撃によって重ウラン酸アンモニウム粒子が変形したことに起因すると思われる。なお、以下に、燃料核（二酸化ウラン粒子）の真球度の評価方法を述べる。   This is considered to be due to the fact that the dripping stock solution has a low viscosity, and an impact upon landing on the ammonia water is applied, and the ammonium heavy uranate particles are deformed by this impact. A method for evaluating the sphericity of fuel nuclei (uranium dioxide particles) will be described below.

[真球度の評価方法]
ＰＳＡ法によって、燃料核（二酸化ウラン粒子）の真球度の評価を行った。ＰＳＡ法とは、図２に示されるように、フォトダイオード、スリット、光源を使用する方法である。光源から照射された光がスリットを通過し、フォトダイオードおよびスリットの間を動く燃料核（二酸化ウラン粒子）の陰影をフォトダイオードにより測定する。フォトダイオードにより測定された燃料核（二酸化ウラン粒子）の陰影により粒子の直径が求められる。以上の測定を燃料核（二酸化ウラン粒子）のあらゆる方向に関して行うことにより、燃料核（二酸化ウラン粒子）の真球度が求められる。 [Evaluation method of sphericity]
The sphericity of the fuel core (uranium dioxide particles) was evaluated by the PSA method. The PSA method is a method using a photodiode, a slit, and a light source, as shown in FIG. The light emitted from the light source passes through the slit, and the shadow of the fuel nucleus (uranium dioxide particles) moving between the photodiode and the slit is measured by the photodiode. The particle diameter is determined by the shadow of the fuel core (uranium dioxide particles) measured by the photodiode. The sphericity of the fuel nucleus (uranium dioxide particles) can be obtained by performing the above measurement for all directions of the fuel nucleus (uranium dioxide particles).

このＰＳＡ法により、１粒子につき、５０回直径を測定し、最大直径/最小直径の比により、１００粒子について真球度を求めた。真球度１．２以上を不良と判断した。   By this PSA method, the diameter was measured 50 times per particle, and the sphericity was determined for 100 particles by the ratio of the maximum diameter / minimum diameter. A sphericity of 1.2 or higher was judged as bad.

（比較例２）
実施例１におけるＰＶＡの添加量を４００ｇに変更した以外は、実施例１と同様にして、滴下原液を得た。すなわち、ＰＶＡの濃度が９．１質量％であるＰＶＡ水溶液を使用した。 (Comparative Example 2)
A dripping stock solution was obtained in the same manner as in Example 1 except that the amount of PVA added in Example 1 was changed to 400 g. That is, a PVA aqueous solution having a PVA concentration of 9.1% by mass was used.

本比較例で得られたＰＶＡ溶液中に残渣が確認され、ＰＶＡが均一に分散したＰＶＡ溶液を得ることができなかった。この滴下原液をアンモニア水中に滴下することにより重ウラン酸アンモニウム粒子を製造した。その後、乾燥工程を経た重ウラン酸アンモニウム粒子の直径面で二つに切断してその裁断面を観察したところ、不均一な内部組織が形成されていることを確認した（図３参照）。これは、ＰＶＡ溶液中のＰＶＡ濃度が高すぎるので、アンモニアと硝酸ウラニルとの反応が、粒子内部まで進行していないことに起因すると思われる。   A residue was confirmed in the PVA solution obtained in this comparative example, and a PVA solution in which PVA was uniformly dispersed could not be obtained. The dripping stock solution was dropped into ammonia water to produce ammonium heavy uranate particles. Then, when it cut | disconnected in the diameter surface of the ammonium biuranium-particles which passed through the drying process and observed the cut surface, it confirmed that the non-uniform | heterogenous internal structure | tissue was formed (refer FIG. 3). This is probably because the PVA concentration in the PVA solution is too high, so that the reaction between ammonia and uranyl nitrate does not proceed to the inside of the particles.

図１は、実施例１で得られた重ウラン酸アンモニウム粒子の裁断面の写真である。1 is a photograph of a cut surface of ammonium deuterated uranate particles obtained in Example 1. FIG. 図２は、燃料核の真球度を評価する方法を示す概略図である。FIG. 2 is a schematic diagram showing a method for evaluating the sphericity of a fuel nucleus. 図３は、比較例２で得られた重ウラン酸アンモニウム粒子の裁断面の写真である。FIG. 3 is a photograph of a cut surface of the ammonium heavy uranate particles obtained in Comparative Example 2.

Claims (3)

水溶性ポリマーと水とを混合して、６〜９質量％の水溶性ポリマー水溶液を調製し、
前記水溶性ポリマー水溶液と水溶性環状エーテルとを混合する
ことを特徴とする硝酸ウラニル含有滴下原液用ポリマー溶液調製方法。 A water-soluble polymer and water are mixed to prepare a 6-9 mass% water-soluble polymer aqueous solution,
A method for preparing a polymer solution for a uranyl nitrate-containing dropping stock solution, wherein the water-soluble polymer aqueous solution and a water-soluble cyclic ether are mixed. 前記水溶性ポリマーと水とを、低くても７５℃に加熱しながら混合する
ことを特徴とする前記請求項１に記載の硝酸ウラニル含有滴下原液用ポリマー溶液調製方法。 The method for preparing a polymer solution for a uranyl nitrate-containing dripping stock solution according to claim 1, wherein the water-soluble polymer and water are mixed while being heated to 75 ° C at least. 前記硝酸ウラニル含有滴下原液に含まれる水溶性環状エーテルの含有量の１〜５０体積％に相当する水溶性環状エーテルと前記水溶性ポリマー水溶液とを、
低くとも５０℃以上で混合する
ことを特徴とする前記請求項１または請求項２に記載の硝酸ウラニル含有滴下原液用ポリマー溶液調製方法。
A water-soluble cyclic ether corresponding to 1 to 50% by volume of the content of the water-soluble cyclic ether contained in the uranyl nitrate-containing dropping stock solution, and the water-soluble polymer aqueous solution,
3. The method for preparing a polymer solution for a uranyl nitrate-containing dripping stock solution according to claim 1 or 2, wherein the mixing is performed at a temperature of at least 50 ° C.
JP2004230481A 2003-12-24 2004-08-06 Method for preparing polymer solution for dripping stock solution containing uranyl nitrate Expired - Fee Related JP4679094B2 (en)

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JP2004230481A JP4679094B2 (en) 2004-08-06 2004-08-06 Method for preparing polymer solution for dripping stock solution containing uranyl nitrate
PCT/JP2004/019171 WO2005061387A1 (en) 2003-12-24 2004-12-22 Liquid stock for dropping, method for preparing liquid stock for dropping, method for preparing uranyl nitrate solution, and method for preparing polyvinyl alcohol solution
EP04807528.7A EP1714943B1 (en) 2003-12-24 2004-12-22 Liquid stock for dropping, method for preparing liquid stock for dropping, method for preparing uranyl nitrate solution, and method for preparing polyvinyl alcohol solution
US10/583,906 US7628970B2 (en) 2003-12-24 2004-12-22 Method of preparing feedstock liquid, method of preparing uranyl nitrate solution, and method of preparing polyvinyl alcohol solution

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05279043A (en) * 1992-03-27 1993-10-26 Nuclear Fuel Ind Ltd Process and apparatus for production of ammonium diuranate particle
JPH0954187A (en) * 1995-08-11 1997-02-25 Nuclear Fuel Ind Ltd Producing method for nuclear fuel pellet using uranium oxide particle as raw material
JPH10332861A (en) * 1997-03-31 1998-12-18 Nuclear Fuel Ind Ltd Method for preparing uranium mononitride

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05279043A (en) * 1992-03-27 1993-10-26 Nuclear Fuel Ind Ltd Process and apparatus for production of ammonium diuranate particle
JPH0954187A (en) * 1995-08-11 1997-02-25 Nuclear Fuel Ind Ltd Producing method for nuclear fuel pellet using uranium oxide particle as raw material
JPH10332861A (en) * 1997-03-31 1998-12-18 Nuclear Fuel Ind Ltd Method for preparing uranium mononitride

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