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Journal Articles

Overview and outcomes of the OECD/NEA benchmark study of the accident at the Fukushima Daiichi NPS (BSAF), Phase 2; Results of severe accident analyses for unit 3

Lind, T.*; Pellegrini, M.*; Herranz, L. E.*; Sonnenkalb, M.*; Nishi, Yoshihisa*; Tamaki, Hitoshi; Cousin, F.*; Fernandez Moguel, L.*; Andrews, N.*; Sevon, T.*

Nuclear Engineering and Design, 376, p.111138_1 - 111138_12, 2021/05

 Times Cited Count:3 Percentile:81.22(Nuclear Science & Technology)

This is the third part of the three part paper describing the accidents at the FDNPS as analyzed in the Phase 2 of the OECD/NEA project "Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Plant" (BSAF). In this paper, we describe the accident progression in unit 3. In the BSAF project, eight organizations from five countries analyzed severe accident scenarios for Unit 3 at the Fukushima Daiichi site using different severe accident codes. The present paper for Unit 3 describes the findings of the comparison of the participants' results against each other and against plant data, the evaluation of the accident progression and the final status inside the reactors. Special focus is on the status of the reactor pressure vessel, melt release and fission product release and transport. Unit 3 specific aspects, e.g., the complicated accident progression following repeated containment venting actuations and attempts at coolant injection at the time of the major core degradation, are highlighted and points of consensus as well as remaining uncertainties and data needs will be summarized. FP transport is analyzed, and the calculation results are compared with dose rate measurements in the containment. The release of I-131 and Cs-137 to the environment is compared with analysis conducted by using WSPEEDI code.

Journal Articles

A Study on precipitation behavior of plutonium and other transuranium elements with N-cyclohexyl-2-pyrrolidone for development of a simple reprocessing process

Morita, Yasuji; Kawata, Yoshihisa*; Mineo, Hideaki; Koshino, Nobuyoshi*; Asanuma, Noriko*; Ikeda, Yasuhisa*; Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Kikuchi, Toshiaki*

Journal of Nuclear Science and Technology, 44(3), p.354 - 360, 2007/03

 Times Cited Count:13 Percentile:69.08(Nuclear Science & Technology)

Precipitation behavior of Pu and other transuranium elements with N-cyclohexyl-2-pyrrolidone (NCP) has been examined to develop a simple reprocessing based only on precipitation method. From HNO$$_{3}$$ solutions containing only Pu, both Pu(VI) and Pu(IV) were precipitated with NCP, but they required more NCP than in the U(VI) precipitation. Selective U(VI) precipitation from HNO$$_{3}$$ solution containing U(VI) and Pu(IV) was achieved by stirring the solution for sufficient time after addition of NCP with ratio of [NCP]/[U]=1.4. Addition of an enough amount of NCP to U(VI)-Pu(VI) or U(VI)-Pu(IV) solutions gave a quantitative precipitation of both U and Pu. Neither Am(III) nor Np(V) was precipitated in the selective U precipitation and the simultaneous U-Pu precipitation. These results demonstrate the feasibility of the reprocessing by precipitation with NCP.

JAEA Reports

Development of fuel microspheres fabrication by the external gelation process

Tomita, Yutaka; Morihira, Masayuki; Tamaki, Yoshihisa*; Nishimura, Kazuhisa*; Shoji, Shuichi*; Kihara, Yoshiyuki; Kase, Takeshi; Koizumi, Tsutomu

JAEA-Research 2006-088, 95 Pages, 2007/01

JAEA-Research-2006-088.pdf:23.02MB

JAEA has developed sphere-pac fuels in the feasibility study on commercialized FBR cycle systems as one of the candidates for low decontamination TRU fuels. Optimization of the fabrication condition for coarse spheres, development of an improved external gelation process, and examination of peculiar problems for the low decontamination fuel were carried out in Phase II. The results are shown as follows. (1) Fabrication condition of coarse spheres was optimized. (2) Feasibility of the improved external gelation process was confirmed. (3) Rare earth elements did not bring any problem for the characteristic of spheres and fabrication condition. (4) Radiation resistant data of the feed solution was acquired. Results of tests show the feasibility of the external gelation process for the low decontamination TRU fuel microsphere fabrication.

Journal Articles

Development of a simple reprocessing process using selective precipitant for uranyl ions; Precipitation behaviors of plutonium and other transuranium elements

Morita, Yasuji; Kawata, Yoshihisa*; Mineo, Hideaki; Koshino, Nobuyoshi*; Asanuma, Noriko*; Ikeda, Yasuhisa*; Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Kikuchi, Toshiaki*

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10

N-cyclohexyl-2-pyrrolidone (NCP) can selectively precipitate U(VI) ions in aqueous nitric acid solutions. Utilizing this property, we have been developing a simple reprocessing process of spent nuclear fuel based only on precipitation method. In the first precipitation step, only U is separated by precipitation in a yield of about 70%, and in the second precipitation step both U and Pu are recovered and separated from fission products (FP) and other transuranium elements (TRU). In JAERI, precipitation behaviors of Pu and other TRU were examined experimentally, and the results showed the feasibility of the process establishement.

Journal Articles

Development of a simple reprocessing process using selective precipitant for uranyl ions; Engineering studies for precipitating and separating systems

Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Kikuchi, Toshiaki*; Morita, Yasuji; Kawata, Yoshihisa*; Mineo, Hideaki; Koshino, Nobuyoshi*; Asanuma, Noriko*; Harada, Masayuki*; et al.

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 4 Pages, 2005/10

N-cyclohexyl-2-pyrrolidone (NCP), can selectively precipitate U(VI) ions in aqueous nitric acid solutions. Utilizing this property, we have been developing a simple reprocessing process of spent nuclear fuel based only on precipitation method. In the first precipitation step, only U is separated by precipitation in a yield of about 70%, and in the second precipitation step both U and Pu are recovered and separated from fission products (FP) and other transuranium elements (TRU). In the present study, a precipitator and a precipitate separator were designed and built up, and were tested with aspets of operationability and system performance.

Journal Articles

Fuel microsphere fabrication tests for sphere-pac fuel by the external gelation process

Tomita, Yutaka; Morihira, Masayuki; Kihara, Yoshiyuki; Tamaki, Yoshihisa*

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 4 Pages, 2005/10

High economic competitiveness and low environmental impact are required for advanced FBR cycle systems. Sphere-pac fuel has been considered as promising fuel systems, due to its inherent advantage in remote operation, dustfree fuel fabrication process and cost reduction. Japan Nuclear Cycle Development Institute (JNC) has been investigated the external gelation process for sphere-pac fuel. In this report, the result of the sphere fabrication test by the external gelation process is reported.

JAEA Reports

Investigation into rationalization of low DF pellet fuel fabrication plant configuration Additional Vol. - Study on characteristics evaluation of low DF fuel fabrication systems -

Maekawa, Kazuhiko*; Yoshimura, Tadahiro*; Hoshino, Yasushi*; Munekata, Hideki*; Tamaki, Yoshihisa*

JNC TJ9420 2005-003, 280 Pages, 2005/02

JNC-TJ9420-2005-003.pdf:4.73MB

In feasibility studies on commercialized FBR cycle system, a comprehensive system investigation and properties evaluation for candidate FBR cycle systems has been implemented through view point of safety, economics, environmental burden reduction, non-proliferation resistively, etc. As part of these studies, an investigation into rationalization of low decontamination pellet fuel fabrication plant configuration, and a study on characteristics evaluation techniques which focused on plant operating rate and waste generation was conducted. Until last fiscal year, a characteristics evaluation simulator which calculates plant operating rate and waste generation by input failure frequency data and periodic replacement data of every equipment or component was developed, and characteristics comparison between multiple fuel fabrication systems was done by applying it. Character of each fuel fabrication system, concerning system stability represented by waste generation, was shown and challenges in characteristics evaluation were made clear. In this fiscal year, programs of the simulator were modified to reflect plant designs correctly by describing campaign operation and batch treatment in the plant in order to make more quantitative calculation possible. On the other hand, in response to the challenges in the characteristics evaluation of last fiscal year, the system properties data based on a certain standard were acquired in conceptual design study and database were created with view of inter-system comparison. As the results of comparison between pellet system and sphere-pac system using simulator, it was suggested that system stability of pellet system is higher than sphere-pac system, and pellet system is also better in environmental burden reduction, because waste generation of sphere-pac system is apparently larger than pellet system.

JAEA Reports

Investigation into rationalization of low decontamination pellet fuel fabrication planat configuration

Maekawa, Kazuhiko*; Yoshimura, Tadahiro*; Hoshino, Yasushi*; Munekata, Hideki*; Tamaki, Yoshihisa*

JNC TJ9420 2005-002, 221 Pages, 2005/02

JNC-TJ9420-2005-002.pdf:7.16MB

In feasibility studies on commercialized FBR cyde system, a comprehensive system investigation and properties evaluation for candidate FBR cycle systems has been implemented through view point of safety, economics, environmental burden reduction, non-proliferation resistivity, etc. As part of these studies, an investigation into rationalization of low decontamination pellet fuel fabrication plant configuration was carried out Until last fiscal year, conceptual design studies of the fuel fabrication plant in 200t-HM/y scale were conducted, and system properties data concerning economics and environmental burden reduction of fuel fabrication plant was acquired. In addition to this, 50t-HM/y scale plant was also schematically studied. In this fiscal year, a rationalization study on conceptual design of 50t-HM/y scale plant was conducted with main aim of economic improvement, and the 200t-HM/y scale plant design was revised based on the recent R&D progress. The system properties data concerning economics and environmental burden reduction of fuel fabrication plant was also acquired. In both case of the 50t-HM/y and 200t-HM/y scale plant, it was suggested that the equipment costs were reduced in several percentages because of reduction of maintenance equipments and cut in line number at the pellet fabrication process although granulation process for denitration converted powder and O/M control process for pellets were added. System properties data for comparative evaluation of candidate fuel fabrication systems was also prepared.

JAEA Reports

Estimation Tests for Effecting Factor on Decontamination Property in Crystallization Process

Kusama, Makoto*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*

JNC TJ8400 2005-006, 88 Pages, 2005/02

JNC-TJ8400-2005-006.pdf:5.67MB

In crystallization unit, UNH (Uranyl Nitrate Hydrate) crystals are washed by a nitric acid solution to get high decontamination factor, but the data on UNH crystals dissolution by washing procedure is insufficient to evaluate the effectiveness of crystallization unit. So, in this study, the effect of a nitric acid concentration to UNH crystals dissolution and decontamination factor was tested. As results, it was found that UNH-crystals dissolution was suppressed as the nitric acid concentration was higher, for example UNH-crystals dissolution by 1N nitric acid washing becomes half as compared with 8N solution washing. And as for the decontamination factor of UNH crystals, it was found that these values by 1N nitric acid washing raised 2-times as compared with 8N nitric acid washing. It was suggested that the decontamination factor of UNH-crystals have the correlation to UNH-crystals dissolution, and shown that UNH crystals loss by washing is 10~20wt% in this experiment.In addition, the crystallization behavior tests used a simulated spent fuel dissolved solution which was prepared by cold FP elements was carried out in a batch-wise experimental method. As results, it was found that in the condition of the feed solution in process design study, Ba element is crystallized with UNH, but other elements were remained in mother liquid. Besides, in the condition of the feed solution contained extreme quantity of Cs than process design concentration, it was found that Cs element was crystallized with UNH. On the other hand, the decontamination factor of other elements except Ba and Cs was about 10 after crystal-liquid separation by filtration, and then increased about 100 after crystal washing. It was confirmed that UNH crystal purity was increased by crystal-liquid separation and washing procedure.

Journal Articles

Development of a simple reprocessing process using selective precipitant for uranyl ions; Engineering studies on systems for precipitating and separating

Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Kikuchi, Toshiaki*; Hanzawa, Masatoshi*; Morita, Yasuji; Ikeda, Yasuhisa*

Progress in Nuclear Energy, 47(1-4), p.414 - 419, 2005/00

 Times Cited Count:3 Percentile:25.79(Nuclear Science & Technology)

The simple reprocessing method based on precipitation using N-cyclohexyl-2-pyrrolidone (NCP) as a selective precipitant for U and Pu ions from dissolved solutions of spent FBR fuels has been developed. On the basis of fundamental studies on precipitation behaviors, we designed and built up the scaled-up laboratory equipments (1/20-scale of future plant capacity of 200 tHM/y) to evaluate technological and economical feasibility. This system, which mainly consists of a precipitator and a precipitate separator, should be operated continuously from economical reasons. From the experimental results, it was confirmed that the precipitator is capable of producing UO$$_{2}$$$$^{2+}$$-NCP precipitate stably with stipulated residence time (approximately 30 min), and the precipitate separator has the highly efficient separation of precipitate from the slurry. Furthermore, the parametric experiments indicated that the rinsing operation increased the efficiency in decontamination of FP elements.

JAEA Reports

Study on characteristics evaluation techniques of low DF fuel fabrication systems (3)

Tanimoto, Ryoji*; Yoshimura, Tadahiro*; Hoshino, Yasushi*; Munekata, Hideki*; Tamaki, Yoshihisa*

JNC TJ9420 2004-003, 212 Pages, 2004/02

JNC-TJ9420-2004-003.pdf:117.29MB

Comparative evaluation of system characteristics such as system safety, economics, environmental burden reduction, etc. concerning candidate fuel fabrication systems are carrying out in the feasibility study on commercialized FBR cycle systems. In its phase II study, a study on characteristics evaluation techniques which focused attention on operating rate of the plant and waste generation started. In last fiscal year, the relationship between operating rate of the plant and waste generation amount was investigated in consideration of failure frequency and periodic replacement of equipments, and perspectives of characteristics comparison between multiple fuel fabrication systems were made clear. In this fiscal year, system characteristics evaluation of each low DF fuel fabrication system was conducted and characteristics comparison between those systems was carried out on the bases of perspectives which made clear last fiscal year. Plant design data obtained for each characteristics evaluation were linked to a database in order to make use of future system design investigation. In addition, system safety represented by operating rate and environmental burden reduction represented by waste generation were chosen as the intended characteristics in this study. In addition to this, programs of the characteristics evaluation simulator which designed until last fiscal year were modified in order to make more accurate calculation possible.

JAEA Reports

Investigation of low decontamination pellet fuel fabrication plant configuration

Tanimoto, Ryoji*; Yoshimura, Tadahiro*; Hoshino, Yasushi*; Munekata, Hideki*; Tamaki, Yoshihisa*

JNC TJ9420 2004-002, 143 Pages, 2004/02

JNC-TJ9420-2004-002.pdf:72.69MB

In the third year of feasibility studies on commercialized FBR cycle system phase II, design consideration of fuel fabrication equipments at lower processes than the fuel element fabrication and line composition examination, regarding low decontamination pellet fuel fabrication facilities, were conducted. Incidental facilities such as flushing and decontamination facilities of solid waste were also studied. A concept of fuel fabrication plant in 200t-HM/y scale was shown as well as system properties data acquisition concerning economics and environmental burden reduction of fuel fabrication plant.

JAEA Reports

Feasibility investigation of a denitration/conversion equipment concept (2)

Tanimoto, Ryoji*; Yoshimura, Tadahiro*; Hoshino, Yasushi*; Munekata, Hideki*; Tamaki, Yoshihisa*

JNC TJ9400 2004-002, 58 Pages, 2004/02

JNC-TJ9400-2004-002.pdf:1.39MB

In this investigation, ceramics denitration containers with ball valve units were manufactured and preliminary tests of microwave denitration, calcination and reduction were carried out in last fiscal year. In this fiscal year, a small scale denitration /conversion apparatus with turntable system was designed and manufactured, then a series of microwave denitration/conversion tests was conducted. Feasibility of the denitration/conversion apparatus with turntable system was evaluated by checking powder properties and soundness of apparatus through the series of tests. The summary of the results are as follows;(1).By the series of microwave denitration, calcination, and reduction tests using small scale denitration/conversion apparatus with turntable system manufactured, it is confirmed that there are no critical problem in the apparatus.(2).Checking the powder properties after grinding, it is confirmed that the powder is equivalent of one obtained by conventional microwave denitration /conversion facility.(3).Reduced powder was grinded and pressed to several pellets, then sintered. It was confirmed that high density pellet fuel can be obtained.(4).Studying the test results from the viewpoint of feasibility of denitration/conversion facility with turntable system, the R&D issues were made clear.

JAEA Reports

The Nuclear-Fuel Manufacturing Adaptability Study of UNH Crystal-Conversion Products

Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Kikuchi, Toshiaki*

JNC TJ8420 2004-002, 48 Pages, 2003/12

JNC-TJ8420-2004-002.pdf:1.33MB

Crystallization procedure is considered to have an adaptability to new reprocessing process based on the PUREX process because it has an advantage in recovering rather pure uranium from contaminated uranium solution without reagent. Hydrated uranyl nitrate (UNH) crystal from crystallization procedure is fed to the conversion process into UO2 for the fabrication of nuclear fuel. We have researched for denitration or conversion methods which is suited to UNH crystal and molten salt since. Due to the selection from some denitration or conversion methods, it is very important to research. an adaptability of the product from the denitration or conversion methods.In this study, we investigated some powder properties of the products, as important factors for nuclear -fuel-manufacturing, from the denitration or conversion methods. Next, we selected pelletizing process, viblo-packing fuel process and covered-particle fuel process as major manufacturing-process of nuclear fuel and research the conditions of uranyl oxide required from each processes. From the comparison between these conditions and the result from denitration or conversion methods, we estimated an adaptability of these methods to nuclear -fuel-manufacturing. As a result, we showed that freeze dry method, ADU and AUC method may be suited to pelletizing process. We also showed that electric reduction method, internal gelation method, and external gelation method may be suited to viblo-packing and covered-particle fuel process.

JAEA Reports

Investigation of low decontamination pellet fuel manufacture line composition

*; *; *; Tamaki, Yoshihisa*; *

JNC TJ9420 2003-003, 133 Pages, 2003/02

JNC-TJ9420-2003-003.pdf:4.79MB

As 2nd fiscal year of phase II of FBR cycle utilization strategy investigation research, following on the denitration conversion process 1ast year, the apparatus design in consideration of remote automation, line composition, and the arrangement design in a cell were performed, and the following result was obtained in this examination about each equipment from pelletizing process to former part of fuel element assembling process of a low decontamination pellet manufacture plant. (1)The outline structure design of each equipment based on remote automatic operation and the conceptual design of a process were performed, and technical formation nature was checked. (2)The formation nature of a maintenance system which conveys the units to maintenance area and repairs was checked at the time of a trouble. (3)The information about failure of the units of each equipment was examined, and operating ratio was evaluated using the plant characteristic simulator which took the throughput and buffer capacity for every process as parameters. (4)About the arrangement plan of equipments in a building, reexamination the arrangement plan of phase I by reflecting the design progress result of each equipment was performed, and accuracy was raised.

JAEA Reports

Foprmation nature investigation of a denitration conversion equipment concept

*; *; *; Tamaki, Yoshihisa*; *

JNC TJ9420 2003-002, 25 Pages, 2003/02

JNC-TJ9420-2003-002.pdf:4.07MB

In this examination, based on the turntable type denitration conversion equipment concept designed last fiscal year, the denitration contaniner made from ceramics was manufactured, the quality tests of powder obtained by microwave denitration of nitric acid uranium solution, calcination, and reduction were performed. The soundness of a denitration container was also checked, and the following result was obtained. (1)As the result of microwave denitration of nitric acid uranium solution in the manufactured denitration container, the usual foamind object was obtained. (2)Denitration product was roughly milled by auger and the prospet to obtain uniform powder was acquired. (3)Physical properties of the powder after calcination and reduction were measured, and the powder was almost equivalent to the conventional one obtained by microwave denitration. (4)Based on the examination result, the formation nature of turntable type denitration conversion equipment was discussed and the development subject was arranged.

JAEA Reports

Ther study of characteristic evaluation techniques about nuclear fuel pellet manufacturing system (2)

*; *; *; Tamaki, Yoshihisa*; *

JNC TJ9400 2003-010, 66 Pages, 2003/02

JNC-TJ9400-2003-010.pdf:4.03MB

In this study, while examining the operating ratio which took into consideration the operation characteristics of apparatus for the low decontamination pelltizing method, and apparatus exchange frequency as the 2nd fiscal year of phase II of FBR cycle utilization strategy investigation research, the system characteristics evaluation simmulator was modified to able to calculate waste amount generated by fixed exchange of the parts. A comparison study of the operating ratio in a few other fabrication system was also performed by applying the simulator to them, and the following result was obtained. (1)While arranging the setting plan of operation characteristics of apparatus in connection with the apparatus operating ratio, optimization of the buffer capacity, throughput, and the number which improve operating ratio was performed. (2)The calculation program of waste amount generated which can respond to the case of fixed exchange of the parts, and the case parts of exchange at the time of failure was made. (3)The comparison method of the system characteristics among fabrication systems was considered, and comparison examination of operating ratio was performed by applying to the other fuel fabrication systems. (4)The simpler method for data input of the characteristic evaluation simulator manufactured in the last fiscal year was examined, and the simulator modification was carried out.

JAEA Reports

The Study of the Feeding and Conveying of UNH Crystal

Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*

JNC TJ8400 2003-031, 62 Pages, 2003/02

JNC-TJ8400-2003-031.pdf:1.64MB

Crystallization procedure is considered to have an adaptability to new reprocessing process based on the PUREX process because it has an advantage in recovering rather pure uranium from contaminated uranium solution without any reagents. Up to now, a small-scale uranium test has been performed to confirm an applicability of crystallization.Hydrated uranyl nitrate (UNH) crystal from crystallization procedure is fed to the conversion process into UO2 for the fabrication of nuclear fuel. UNH crystal as feed material has the advantage over UNH solution because any reagents aren't needed in the conversion process. Therefore we will develop an apparatus for storing and conveying UNH crystal to the conversion process. Flowability of UNH crystal is very important to design the apparatus. Carr's fluidity index is one of the most common expressions for the flowability of powders.In this study, we estimated Carr's fluidity index of UNH crystal. Based on the Carr's fluidity index, we investigated the adaptability of the apparatus to UNH crystal.

JAEA Reports

The Study to wash UNH crystals in the reprocessing process

*; *; Tamaki, Yoshihisa*

JNC TJ8400 2003-016, 40 Pages, 2003/02

JNC-TJ8400-2003-016.pdf:0.9MB

Crystallization procedure is considered to have an adaptability to new reprocessing process based on the PUREX process because it has an advantage in recovering rather pure uranium from contaminated uranium solution without any reagents. Up to now, a small-scale uranium test has been performed to confirm an applicability of crystallization. We focus on the decontamination factor (DF) of FP in the crystallization procedure. Some mock experiments have been also performed and suggested that most of FP is on the surface of crystals in mother liquor. We expected that the content of the mother liquor decreases with increasing of the size of crystals. Consequently it is possible that the DF increases with increasing of the size of crystals. In this study, we performed the experiment to estimate the DF of Ce (ⅵ) of various size of UNH crystals. And our expectation is confirmed.

JAEA Reports

The Study of the super-saturated concentration of UNH solution

*; *; Tamaki, Yoshihisa*

JNC TJ8400 2003-015, 28 Pages, 2003/02

JNC-TJ8400-2003-015.pdf:0.68MB

Crystallization procedure is considered to have an adaptability to new reprocessing process based on the PUREX process because it has an advantage in recovering rather pure uranium from contaminated uranium solution without any reagents. Up to now, a small-scale uranium test has been performed to confirm an applicability of crystallization. We have a suggestion to increase the amount of product from crystallization procedure. Firstly, we keep the UNH solution at the first degree of super-saturated concentration before crystallization. While keeping the degree, primary nucleation progresses in the solution. This treatment will increase the amount of UNH crystal from the solution by the time. Our other suggestion is to increase the decontamination factor of product. For this purpose, we should restrain secondary nucleation due to increase the size of UNH crystal. If the UNH solution is kept at degree between saturated and super-saturated concentration, it would cause to increase the size of UNH crystal while crystallizing. In this study, we estimate the degree of super-saturated concentration of UNH solution concerning the reprocessing process.

23 (Records 1-20 displayed on this page)