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Chikazawa, Yoshitaka; ; Nishiguchi, Yohei; Konomura, Mamoru
JNC TN9400 2002-068, 77 Pages, 2002/12
In the Feasibility Study of JNC, sodium cooled large-scale fast reactor and medium-scale modular reactor are studied as two of promising concepts. Sodium cooled medium-scale modular reactor has disadvantage compared to large-scale reactor that has large-scale effect. To compensate the disadvantage, modular effects are facilitated to improve facility sharing among modules, learning effect and so on. But facility sharing makes the plant system complex and impacts to plant safety and operations are worried. We evaluated the impacts to plant safety and operations by facility sharing in sodium cooled medium-scale modular reactor. We arranged ideas of facility sharing and extracted four ideas which are considered to have big impacts to safety or operations. (1)Sharing of the central control room (2)Reduction of emergency generators (3)Adoption of large capacity turbines (4)Sharing of auxiliary cooling water system In this study, we evaluated impacts to safety operability, annual inspection and availability under consideration of the risk for unscheduled shutdown against above four facility sharing plans. Consistency of the facility sharing was confirmed.
Chikazawa, Yoshitaka; ; ; Shiotani, Hiroki;
JNC TN9400 2002-055, 438 Pages, 2002/10
JNC-TN9400-2002-055.pdf:25.85MB
Small sized fast breeder reactors have a potential to use a power source applicable to diversified social needs. In the Feasibility Study of JNC, we will make a concept of small sized fast breeder reactor with various requirements of economical competitiveness, reactor safety, very long lived core, etc. The design requirements for a small sodium cooled fast reactor in Fiscal Year 2001 (FY 2001) were defined as follows; (Small sodium cooled reactor) (1)Electric Power : 150MWe (2)Fue1 Type : Metal (3)Coolant Circulation System : Forced Circulation (Tank or Loop Type) (4)Core Life : 10 years Based on a previous study of a small sodium cooled reactor, cost reduction of the plant with an electrical power of 150MWe was pursued. Concepts of its fuel, core and plant were designed and their main specifications were determined. The Reactor vessel was minimized and the diameter of the reactor vessel became 4 m. The reactor system was enhanced a passive safety to avoid a core melt even at ATWS. The construction cost of the whole plant was evaluated 340,000 yen/kWe and the economical goal (350,000 yen/kWe) was achieved. The constitution of a decay heat removal system was chosen which was a system of two PRACS and one RVACS driven by natural circulation in order to satisfy a heat removal condition of Category IV in Japanese Standard. Design Concept of a multipurpose reactor was studied. The purpose of the reactor was to produce hydrogen. It was performed with a membrane steam reformer. A potential to achieve the economical goal (17 yen/Nm
) is shown.
Chikazawa, Yoshitaka; ;
JNC TN9400 2002-052, 242 Pages, 2002/10
JNC-TN9400-2002-052.pdf:7.03MB
Small sized fast breeder reactors have a potential to use a power source applicable to diversified social needs. In the Feasibility Study of JNC, we will make a concept of small sized fast breeder reactor with various requirements of economical competitiveness, reactor safety, very long lived core, etc. The design requirements for a small lead-bismuth cooled fast breeder reactor in Fiscal Year 2001 (FY2001) were defined as follows; (1)electric power: 50 MWe, (2)fuel type: mixed nitride fuel, (3)reactor type: tank type (no secondary cooling system), (4)coolant circulation system: natural circulation, (5)fuel exchanging system: handling of each fuel subassembly, and (6)core life: 30 years. In order to reduce construction cost of the plant, the concept of a fuel exchanging system was changed to a conventional subassembly handling type as comparing a whole-core handling type in a study in FY 2000. And balance of power of the coolant system was reevaluated. Though a reevaluated diameter of the reactor vessel (3.85 m) was larger than that of a previous design (3.7 m) in FY2000 because of a change of the core size, the total mass of nuclear steam supply system was reduced from 324 tons to 259 tons with simplified reactor structure owing to no requirement of a whole-core handling mechanism. The constitution of a decay heat removal system was chosen which was a system of one PRACS and ONE RVACS driven by natural circulation in order to satisfy a heat removal condition of Category IV in Japanese Standard. The construction cost of the plant was estimated at 800,000 yen/kWe which was much higher than the target value, that is, 350,000 yen/kWe (5.5yen/kWh), because of a scale demerit coming from a low power and a usage of heavy reactor components for lead-bismuth coolant. But it would have some possibility to reduce the construction cost with an increasing of a reactor power, a common use of some BOP components among reactors and a learning effect of construction.
; Kawasaki, Nobuchika; ;
JNC TY9400 2002-018, 527 Pages, 2002/09
JNC-TY9400-2002-018.pdf:30.48MB
no abstracts in English
Fujii, Tadashi; ; ; Sakai, Takaaki; ; Oki, Yoshihisa;
JNC TN9400 2002-049, 78 Pages, 2002/09
JNC-TN9400-2002-049.pdf:3.72MB
The conceptual design study of the large-scale sodium-cooled reactor is in progress in the "Feasibility Study on Commercialized Fast Reactor Cycle Systems (F/S)". The direct water pool storage system is being examined as a candidate concept to simplify the fuel handling facility for the sodium-cooled reactor. In this concept, the decay heat of a fuel subassembly is relatively higher (18kW which is about 4.5 times of the Ex-vessel Storage Tank system in the demonstration FBR). Therefore, the information about the cooling characteristics of the fuel subassembly are lacking in cases of submergence process at a normal operation and cooling water injection process from upper part of the subassembly at a transfer accident. Accordingly, the understanding of the cooling characteristics of the fuel subassembly in higher decay heat condition was pointed out as one of the thermal hydraulic problems which influence the realization of the plant concept. Using the single heater pin equipment, fundamental tests were conducted with the parameters of the thermal conditions of a fuel pin, the outlet shapes of it, the submergence speeds and so on. Then, following basic data were acquired to be reflected in the actual plant design. (1)Cooling modes of the normally submergence tests and water injection tests were identified by visualization of the boiling behavior in the test section and the temperature change of the heater pin. (2)The initial temperature of the heater surface and the blockage size of the outlet of test section were dominating factors to the cooling completion time. (3)Maximum temperature rise of the heater surface was about 4K in normally submergence tests and 6K in water injection tests, respectively. Therefore, the heater was well cooled without significant temperature rise.(4)In the normally submergence tests, the pressure of the upper part of the test section did not exceed the lower part pressure and a water level rise in the test section was not obstructed ...
Moribe, Takeshi; ; ;
JNC TY9400 2002-008, 150 Pages, 2002/06
JNC-TY9400-2002-008.pdf:7.26MB
no abstracts in English
Shimakawa, Yoshio; Nibe, Nobuaki; ; Fujii, Tadashi; ; Uchita, Masato; Chikazawa, Yoshitaka
JNC TY9400 2002-007, 62 Pages, 2002/05
JNC-TY9400-2002-007.pdf:3.62MB
no abstracts in English
Shimakawa, Yoshio; Nibe, Nobuaki; ; Fujii, Tadashi; ; Uchita, Masato; Chikazawa, Yoshitaka
JNC TY9400 2002-006, 94 Pages, 2002/05
JNC-TY9400-2002-006.pdf:4.66MB
no abstracts in English
; Soman, Yoshindo; ; ;
JNC TN9400 2002-029, 92 Pages, 2002/05
JNC-TN9400-2002-029.pdf:2.38MB
A primary sodium pump is installed in the center of an integrated component and heat transfer tubes surround the pump. Then, the pump rotation induces the vibration of heat transfer tubes and it leads the tubes to fretting wearing against support plates. Therefore, the tube wearing must be evaluated to confirm its integrity during the plant life span(60 years). This report describes the results of the tube wearing analysis by using vibration and wearing calculation models. In the first place, the vibration analysis of a pump shaft, shells, tube bundle etc. of the integrated component reveals its properties such as frequency, amplitude and vibration mode. In the second place, based on the above mentioned vibration analysis, the wearing analysis model shows the frequency and amplitude of the fretting wearing between tubes and support plates and the wearing depth of tubes. The amplitude of the pump vibration, vibration transmission paths and the contact condition between tubes and support plates especially affect the tube wearing, then the wearing evaluation needs that conservative calculation conditions must be found out by surveying these parameters. This calculation result indicates that the tube abrasion does not affect the tube integrity during the plant life time. However further evaluation by more detailed analysis and vibration and wearing tests are needed to acqire more accurate results.
; Igawa, Kenichi*
JNC TN9400 2002-019, 81 Pages, 2002/05
JNC-TN9400-2002-019.pdf:2.21MB
The cost minimization of commercialized FBR plant systems requires the integration of an intermediate-heat-exchanger (IHX) and a primary sodium mechanical pump into one component. The pump is installed in the center of the integrated component and heat transfer tubes surround the pump. Primary sodium flows down inside the heat transfer tubes and secondary sodium flows up outside the tubes in a zigzag. Therefore, the pump rotation and sodium flow induce the vibration of heat transfer tubes and it leads the tubes to fretting wearing against support plates. Then the tube wearing must be evaluated to confirm its integrity during the plant life span (60 years). However, the knowledge of the pump rotation influence on tube wearing is not sufficiently acquired because the integrated component is a new concept in JNC. To evaluate the tube fretting wearing ratio due to the pump rotation, a new calculation model of FINAS was composed. In the first place, the beam vibration analysis model of a pump shaft, shells, tube bundle etc. of the integrated component reveals its properties such as frequency, amplitude and vibration mode. In the second place, based on the above mentioned vibration analysis, the frequency and amplitude of abrasion between the tubes and support plates can be obtained by a contact analysis model of FINAS. Eventuany, this calculation shows that the tube wearing will not affect the tube integrity during the plant life time. However further evaluation by more detailed analysis and abrasion tests are needed to obtain more accurate results.
Shimakawa, Yoshio; Ohshima, Hiroyuki; Okano, Yasushi; ; Kamiyama, Kenji; ;
JNC TN9400 2001-107, 147 Pages, 2001/11
JNC-TN9400-2001-107.pdf:5.26MB
The Phase I of feasibility study & commercialized fast reactor cycle systems was performed, and then a Large-scale (1500MWe) loop-type reactor (Twin plant type) and a medium-scale (500MWe) loop-type reactor (Modular type) have been screened as promising design concepts of sodium-cooled reactor. As a result of estimation for the economic competitiveness, prospect to attain the design goal (Plant construction const is below 200000yen/kWe) has been obtained for each concept, however, the cost of medium scale type reactor was higher than that of large scale type reactor, the necessity of further rationalization was indicated. In order to create and examine ideas for rationalization of medium-scale reactors, "Working group for creating new concepts of medium-scale reactors" was organized. In the group, not only a lot of ideas are proposed, classified and arranged but also seven important examination items are selected as subjects for commercialized FBR and concentrated arguments are held about them. This report summarizes the results of activity of this group.
; ; Kida, Masanori; ; ; ; Hayashi, Hideyuki
JNC TN9400 2001-073, 414 Pages, 2001/06
JNC-TN9400-2001-073.pdf:10.15MB
The phase I feasibility studies on commercialized fast reactor cycle system was conducted until FY2000. In the phase I study, the preliminary designs of the three gas cooled FBR concepts expected to have competitive cost performance with LWR were investigated. The three concepts are (1)Carbon dioxide cooled FBR using pin type fuel, (2)Helium cooled FBR using pin type fuel, (3)Helium cooled FBR using coated particle fuel. This report summarizes the results of the preliminary design study on helium cooled FBR using coated particle fuel conducted until March 2001. The helium cooled FBR plant accomplishes direct gas turbine cycle of high efficiency using heat resisted coated particle fuel and reactor inner structures. The plant also performs core melt proof concept by high temperature performance, negative Doppler coefficient and natural circulation cooling. The plant pursues safety and cost effective concept by the removal of CDA countermeasures, high plant efficiency and realistic twin plant design with modularization. The results have shown that the plant has the possibility of core melt proof safety although the core performance is not sufficient. The plant construction cost is thought to be a little higher than the expected cost and has the possibility to reach the target. The future R&D especially for coated particle fuel and fuel assembly is necessary.
JNC TN9400 2000-083, 78 Pages, 2000/07
JNC-TN9400-2000-083.pdf:2.95MB
For commercialization of FBR (Fast Breeder Reactor), the reactor safety systems are needed not only to have necessary and enough reliability but also to decrease the amount of materials in order that the FBR has economical competitiveness against LWR (Light Water Reactor) and another electrical power supply systems. ln this study, reliability assessment, which calculates the occurrence frequencies of PLOHS (Protected Loss Of Heat Sink) sequences, was performed for three kinds of large size sodium cooled fast reactors with decreased number of loops and of support systems examined in the Feasibility Studies on Commercialized FBR System. The realistic evaluation was performed using the failure rate data of components based on the domestic LWR operating experience. The result is: (1)AIl of the three kinds of commercialized FBR concepts are expected to achieve the frequencies of PLOHS sequences caused by internal events of the plant under 10
/ry, assuming that common-mode-failure is excluded. ln addition, the dominating cause of the coincidence of the incidents and the information that improves reliability of decay heat removal systems are summarized for each concept. (2)In order to evaluate design margin, the reliability assessment was performed in the case that the capacity of natural circulation cooling was reinforced from 100%/3
3 loops to 50%3 loops or fiom 25%4 loops to 100%/34 loops easing to succeed decay heat removal. ln that case, it is confirmed that the frequencies of PLOHS sequences decrease by about one order of magnitude.
; ; ; ;
JNC TN9400 2000-079, 189 Pages, 2000/07
JNC-TN9400-2000-079.pdf:5.94MB
Based on the medium and long-term program of JNC, the feasibility study for fast breeder reactors (FBRs) including related nuclear fuel cycles has been started from the 1999 fiscal year. Various options of FBR plant systems have been studied and a concept of Heavy Liquid Metal cooled FBRs is one of these options. The purpose of this paper is to research and evaluate Heavy Liquid Metal cooled FBRs on the basis of literatures. First, we selected four types of plant concepts listed below. Concept 1: Large-scale pond type reactor with Pb cooled. Concept 2: Large-scale loop type reactor with Pb cooled. Concept 3: Medium-scale module tank type reactor with Pb cooled. Concept 4: Small scale module tank type reactor with Pb-Bi cooled. Concept l and 2 are selected to seek for scale merit on economical aspect. ln Concept 3 and 4, we tried to reduce the inventory of HLMC and to ease the load conditions on structures and seek for competitiveness with module effect such as mass production and learning effect. Through a preliminary design study, we identified some technical features of each concept and roughly evaluated economical competitiveness based on total weight of the NSSSs. From this study, we concluded (1)lngeneral, the large-scale type concepts have little economical advantage because of its huge amount of material needed for its severe load conditions. (Concept 1&2) (2)Even for the large-scale pond type reactor, the conclusion seems to be the same. Total amount of the thermal shielding material became huge. Aseismatic structure makes the amount of material increase under the Japanese seismic condition. (Concept1) (3)For the large-scale loop type reactor, we selected side entry and dual walled piping concept with slide-joint inner wall to cope with thermal expansion of piping system. However, there seemed to be difficulty with compatibility between slide-joint and oxide film corrosion prevention measures. (Concept2) (4)The medium and small modular type ...
Hayafune, Hiroki; Shimakawa, Yoshio; ; ; ;
JNC TN9400 2000-107, 156 Pages, 2000/06
JNC-TN9400-2000-107.pdf:5.98MB
The objective of this study is to create the FBR plant concepts increasing economy and safety for the Phase-I "Feasibility Studies on Commercialized Fast Reactor System". In this study, various concepts of simplified 2ry cooling system for sodium cooled FBRs are considered and evaluated from the view points of technological feasibility, economy, and safety. The concepts in the study are considered on the basis of the following points of view. (1)To simplify 2ry cooling system by moderating and localizing the sodium-water reaction in the steam generator of the FBRs. (2)To simplify 2ry coolig system by eliminatig the sodium-water reaction using integrated IHX-SG unit (3)To simplify 2ry cooling system by eliminating the sodium-water reaction using a power generating system other than the steam generator. As the result of the study, 12 concepts and 3 innovative concepts are proposed. The evaluation study for those concepts shows the following technical prospects. (1)2 concepts of integrated IHX-SG unit can eliminate the sodium-water reaction (a)Separated IHX and SG tubes unit usig Lead-Bismuth as the heat transfer medium (b)lntegrated IHX-SG unit using copper as the heat transfer medium (2)Cost reduction effect by simplified 2ry cooling system using integrated IHX-SG unit is estimated 0 to 5%. (3)A11 of the integrated IHX-SG unit concepts have more weight and larger size than an conventional steam generator unit. The weight of the unit during transporting and lifting would limit capacity of heat transfer system. These evaluation results will be compared with the results in JFY 2000 and used for the Phase-II study.
Kawasaki, Nobuchika; ; ; ; ;
JNC TN9400 2000-085, 99 Pages, 2000/06
JNC-TN9400-2000-085.pdf:5.85MB
ln the framework of feasibility studies on commercialized fast breeder reactor (FBR) system, advanced concepts of FBRs are being investigated aiming to achieve generation cost of 5 k/kWh for the FBR system in the future. In order to achieve this economic target, it is expected to reduce the construction cost for 1,500 MWe FBR power plants to below 200 k/kWe. As a consideration of economics of FBR plants, the following studies were conducted in JFY1999: study on cost reduction scenarios, estimation of the construction costs of large scale sodium cooled FBR plants by the cost evaluation code SCES-FBR, and arrangement of plant commodity data base. Principal results are as follows: (1)Cost reduction scenarios for FBRs with diverse coolants were studied and cost reduction technologies applicable to those plants were extracted. (2) Plant commodities were compared between the Demmonstration FBR (Phase I Design) and a large scale sodium cooled FBR plant (Preliminary design), and cost of the large scale plant was estimated as based on the construction cost of the Demmonstration FBR. Results of these studies showed that the total amount of 2,500 tons for structural materials of main components in NSSS will be a value to achieve the construction cost target in case of 1,500 MWe sodium cooled FBR power plant. (3) The several plant concepts which were studied in JFY1999 as a candidate for the 1,500 MWe sodium cooled FBR power plant were evaluated by SCES-FBR in respect to their construction cost. The results showed that they have a potential to achieve the construction cost target. Effects on the construction cost reduction by common use of facilities in a twin plant and by decrease of number of cooling loops were also estimated to be approximately 23 k/kWe and 6 k/loop, respectively.
Nibe, Nobuaki; Shimakawa, Yoshio; ; Hayafune, Hiroki; ; ;
JNC TN9400 2000-074, 388 Pages, 2000/06
JNC-TN9400-2000-074.pdf:13.32MB
Large sized sodium-cooled fast breeder reactors of large-size are being studied and have been operated in Japan and many countries. ln this feasibility study, evaluation was made on technical feasibinty for design concepts or 1 loop type and 3 pool types, specially from the viewpoint of improvement of economical competence. The design concepts include the ideas of cost reduction measures such as large-scaled components, reduction of loop number and integration of components on the basic of utilization of sodium characteristics. From the results of the evaluation, it may be possible for all the concepts to attain the economical target of 200 thousands yen per kilowatt, though further confirmation should be made for technical feasibility of those concepts. ln addition, the following items were listed up as further cost-reduction measures. (1)Higher temperature cooling system and steam cycle efficiency (2)Shortening of construction term (3)Reduction of safety systems by using measuring instruments with high performmce (4)Adoption of SG-ACS
Ogo, Hideyasu; ; ; ;
JNC TN9400 2000-073, 78 Pages, 2000/06
JNC-TN9400-2000-073.pdf:2.32MB
ln the feasibility studies on commercialized fast reactor cycle system started in July 1999, according to a medium and long-term R&D project and management plan of JNC, various candidate concepts for a fast reactor cycle system are investigated to have good cost performance competitive with LWR system and the related R&D progTams, ln this report candidate fast reactor concepts using various coolants are studied and the related R&D items are picked up, Three concepts of the gas cooled reactor have been selected as follows. (A)Carbon dioxide cooled reactor using fuel pin (B)Helium cooled reactor using fuel pin (C)Helium cooled reactor using coated fuel particles Concept (A) and (C) have been studied concerning the following items in FY1999. (1)Basic specifications (2)Conceptual design of core and fuel (3)Conceptual design of major components (4)Safety design and analysis (5)Countermeasures against core disruptive accidents (6)Reprocessing procedures of coated fuel particles The result of the investigation revealed that the following issues have to be solved in order to realize each concept. For concept (A); how to take counter measures against recriticality from the viewpoint of core performance, feasibility of debris tray (core catcher) to retain molten fuel in coolable and subcritical geometry and development of a large scale gas circulator, etc. For concept (C); development of coated fuel particles, fuel subassemblies, and a helium gas turbin, etc.
; ; ; ;
JNC TN9400 2000-066, 52 Pages, 2000/06
JNC-TN9400-2000-066.pdf:1.82MB
Phase I of feasibility studies on commercialized fast reactor system is being peformed for two years from Japanese Fiscal Year 1999. In this report, results of the study on fluid fuel reactors (especialiy a molten salt fast breeder reactor concept) are described from the viewpoint of technical and economical concerns of the plant system design. ln JFY1999, we have started to investigate the fluid fuel reactors as alternative concepts of sodium cooled FBR systems with MOX fuel, and selected the unique concept of a molten chloride fast, breeder reactor, whose U-Pu fuel cycle can be related to both light water reactors and fast breeder reactors on the basis of present technical data and design experiences. We selected a preliminary composition of molten fuel and conceptual plant design through evaluation of technical and economical issues essential for the molten salt reactors and then compared them with reference design concepts of sodium cooled FBR systems under limited information on the molten chloride fast breeder reactors. The following results were obtained. (1)The molten chloride fast breeder reactors have inherent safety features in the core and plant performances, ad the fluid fuel is quite promising for cost reduction of the fuel fabrication and reprocessing. (2)On the other hand, the inventory of the molten chloride fuel becomes high and thermal conductivity of the coolant is inferior compared to those of sodium cooled FBR systems, then, the size of main components such as lHX's becomes larger and the amount of construction materials is seems to be increased. (3)Furthermore economical vessel and piping materials which contact with the molten chloride salts are required to be developed. From the results, it is concluded that further steps to investigate the molten chloride fast breeder reactor concepts are too early to be conducted.
Kamiyama, Kenji; ;
JNC TN9400 2000-064, 72 Pages, 2000/06
JNC-TN9400-2000-064.pdf:3.07MB
Based on the medium and long-term program of JNC, the feasibility study for fast breeder reactors (FBRs) including related nuclear fuel cycles has been started from the 1999 fiscal year. Various options of FBR plant systems have been selected and a concept of water-cooled FBRs is one of these options. The purpose of this paper is to research and evaluate the water-cooled FBRs on the basis of literatures. The following three concepts, which premise to make use of current light water reactor technology, were selected based on the research of current studies: A high conversion BWR with high void fractions and super-frat core, a high conversion PWR using heavy water as a coolant, and a supercritical pressure light water cooled FBR in which the average coolant density is so small that the breeding is possible and which can achieve the high thermal efficiency over 40%. Features of each concept were reviewed and then evaluation was performed from the following three viewpoints: The long-term targets (subject to safety, market competitiveness as an energy system, utilization of uranium resources, reduction of radioactive waste, security of the non-proliferation), the technical possibility (the structure integrity including the earthquake resistance, safety, productivity, operability and maintenance repair, difficulty of the development) and developmental risk. The evaluation showed that there was no problem with high developmental risk although it is difficult to achieve a high breeding ratio. However, it is desirable to confirm the thermal hydraulics of the core. Furthermore, as regards the high conversion BWR, whose study progressed the most so far, the fundamental feasibility of the breeding core was confirmed, since the method of the nuclear calculation was verified for the configuration of this study and criteria of design basis events were satisfied in the evaluation. ln the 2000 fiscal year, evaluation will be made about nuclear characteristics, reactor safety and m
; Kawasaki, Nobuchika; ; *; ; ;
JNC TN9400 2000-063, 221 Pages, 2000/06
JNC-TN9400-2000-063.pdf:8.68MB
ln this paper, feasibility of the multipurpose small fast reactor, which could be used for requirements concemed with various utilization of electricity and energy and flexibility of power supply site, is discussed on the basis of examination of literatures of various small reactors. And also, a possibility of economic improvement by learning effect of fabrication cost is discussed for the modular-sized reactor which is expected to be a base load power supply system with lower initial investment. (1) Multipurpose small reactor (a) The small reactor with 10MWe
150MWe has a potential as a power source for large co-generation, a large island, a middle city, desalination and marine use. (b) Highly passive mechanism, long fuel exchange interval, and minimized maintenance activities are required for the multipurpose small reactor design. The reactor has a high potential for the long fuel exchange interval, since it is relatively easy for FR to obtain a long life core. (c) Current designs of small FRs in Japan and USA (NERI Project) are reviewed to obtain design requirements for the multipurpose small reactor. (2) Modular-sized reactor (a) ln order that modular-sized reactor could be competitive to 3200MWe twin plant (two large monolithic reactor) with 200k/kWe, the target capital cost of FOAK is estimated to be 260k/kWe for 800MWe modular, 280k/kWe for 400MWe modular and 290k/kWe for 200MWe by taking account of the learning effect. (b)As the result of the review on the current designs of modular-sized FRs in Japan and USA (S-PRISM) from the viewpoint of economic improvement, since it only be necessary to make further effort for the target capital cost of FOAK, since the modular-sized FRs requires a large amount of material for shielding, vessels and heat exchangers essentially.