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Journal Articles

Activation, Radiation shielding materials

Sukegawa, Atsuhiko; Iida, Hiromasa*; Itoga, Toshio*; Okumura, Keisuke; Kai, Tetsuya; Konno, Chikara; Nakashima, Hiroshi; Nakamura, Takashi*; Ban, Shuichi*; Yashima, Hiroshi*; et al.

Hoshasen Shahei Handobukku; Kisohen, p.299 - 356, 2015/03

no abstracts in English

Journal Articles

Nuclear analysis of ITER equatorial EC launcher

Takahashi, Koji; Iida, Hiromasa*; Kobayashi, Noriyuki*; Kajiwara, Ken; Sakamoto, Keishi; Omori, Toshimichi*; Henderson, M.*

Fusion Science and Technology, 63(1T), p.156 - 159, 2013/05

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Nuclear analysis of the ITER equatorial EC launcher has been carried out to determine heat and/or particle loads on its components and also to evaluate the possibility of "hands-on maintainability" (personnel accessibility) to the launcher back-end. Monte Carlo code "MCNP5" is applied to simulate the radiation leak from fusion plasma to the special region around the launcher. The results indicate a significant radiation leak at the gaps between the port walls and port plug frame and at the waveguide bundles in the launcher. Another significant neutron leakage is through the port wall consisting of only stainless steel but without light isotopes such as water. The shut down dose rates was estimated at the port interspace behind the launcher at the level of the required value of 100 $$mu$$Sv/h. This analysis offers the potential to modify the launchers shielding layout to minimize the above leakage and further reduce the shut down dose rates in the regions of personnel access.

Journal Articles

Development of CAD-MCNP interface program GEOMIT and its applicability for ITER neutronics design calculations

Nasif, H. R.*; Masuda, Fukuzo*; Morota, Hidetsugu*; Iida, Hiromasa*; Sato, Satoshi; Konno, Chikara

Nuclear Technology, 180(1), p.89 - 102, 2012/10

 Times Cited Count:3 Percentile:66.51(Nuclear Science & Technology)

GEOMIT is the CAD/MCNP conversion interface code. It is developed to automatically generate Monte Carlo geometrical data from CAD data due to the difference in the representation scheme. GEOMIT is capable of importing different CAD format as well as exporting different CAD format. GEOMIT has a capability to produce solid cells as well as void cells without using complement operator. While loading the CAD shapes (Solids), each shape is assigning material number and density according to its color on the original CAD data. Shape fixing process is been applied to cure the errors in the CAD data. Vertices location correctness is evaluated first, then a removal of free edges and removal of small faces processes. Binary Space Portioning (BSP) tree technique is used to automatically split complicated solids into simpler cells to avoid excessive complicated cells for MCNP to run faster. MCNP surfaces are subjected to an automatic reduction before creating the model. CAD data of International Thermonuclear Experimental Reactor (ITER) benchmark model has been converted successfully to MCNP geometrical input. MCNP input model validations have been carried out by checking lost particles and comparing volumes calculated by MCNP to those of the original CAD data. Different test cases have been evaluated for the ITER, include Blanket first wall heat loading calculations, surface fluxes and volume fluxes at different divertor regions as well as TF coils heating.

Journal Articles

Progress of conversion system from CAD data to MCNP geometry data in Japan

Sato, Satoshi; Nashif, H.*; Masuda, Fukuzo*; Morota, Hidetsugu*; Iida, Hiromasa*; Konno, Chikara

Fusion Engineering and Design, 85(7-9), p.1546 - 1550, 2010/12

 Times Cited Count:5 Percentile:57.64(Nuclear Science & Technology)

Automatic conversion systems from CAD data to MCNP geometry input data have been developed to convert the CAD data of the fusion reactor with very complicated structure. So far, three conversion systems (GEOMIT-1, ARCNCP and GEOMIT-2) have been developed. The void data can be created in these systems. GEOMIT-1 was developed in 2007, and a lot of manual shape splitting works for the CAD data were required to successfully convert the complicated geometry. ARCNCP was developed in 2008. The algorithm has been drastically improved on automatic creation of ambiguous surface in ARCNCP, and manual shape splitting works can be drastically reduced. The latest system, GEOMIT-2, does not require additional commercial software packages, though the previous systems require them. It has also functions of the CAD data healing and the automatic shape splitting. The geometrical errors of the CAD data can be automatically revised by the healing function, and the complicated geometries can be automatically split into the simple geometries by the shape splitting function. Any manual works are not required in GEOMIT-2. The latest system is very useful for nuclear analyses of fusion reactors.

Journal Articles

Development of CAD-to-MCNP model conversion system and its application to ITER

Sato, Satoshi; Iida, Hiromasa; Ochiai, Kentaro; Konno, Chikara; Nishitani, Takeo; Morota, Hidetsugu*; Nashif, H.*; Yamada, Masao*; Masuda, Fukuzo*; Tamamizu, Shigeyuki*; et al.

Nuclear Technology, 168(3), p.843 - 847, 2009/12

 Times Cited Count:6 Percentile:52.73(Nuclear Science & Technology)

It takes huge or unrealistic amounts of time to prepare accurate calculation inputs in shielding design for very large and complicated structure such as fusion reactors. For that reason, we have developed an automatic conversion system from three dimensional CAD drawing data into input data of the calculation geometry for a three dimensional Monte Carlo radiation transport calculation code MCNP, and applied it to an ITER benchmark model. This system consists of a void creation program (CrtVoid) for CAD drawing data and a conversion program (GEOMIT) from CAD drawing data to MCNP input data. CrtVoid creates void region data by subtracting solid region data from the whole region by Boolean operation. The void region data is very large and complicated geometry. The program divides the overall region to many small cubes, and the void region data can be created in each cube. GEOMIT generates surface data for MCNP data based on the CAD data with voids. These surface data are connected, and cell data for MCNP input data are generated. In generating cell data, additional surfaces are automatically created in the program, and undefined space and duplicate cells are removed. We applied this system to the ITER benchmark model. We successfully created void region data, and MCNP input data. We calculated neutron flux and nuclear heating. The calculation results agreed well with those with MCNP inputs generated from the same CAD data with other methods.

Journal Articles

Attila validation with fusion benchmark experiments at JAEA/FNS

Konno, Chikara; Sato, Satoshi; Ochiai, Kentaro; Wada, Masayuki*; Onishi, Seiki; Takakura, Kosuke; Iida, Hiromasa

Nuclear Technology, 168(3), p.743 - 746, 2009/12

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

The three-dimensional Sn code Attila of Transpire, Inc. can use CAD data as a geometrical input directly and deal with assemblies of complicated geometry without much effort. ITER organization has a plan to adopt this code as one of the standard codes for nuclear analyses. However validation of calculations with this code is not carried out in detail so far. Thus we validate this code through analyses of some bulk experiments and streaming experiments with DT neutrons at JAEA/FNS. Analyses with the Sn code system DOORS and Monte Carlo code MCNP4C were also carried out for comparison. Agreement between Attila and DOORS calculations is very good for the bulk experiments. For streaming experiments Attila requires special treatments (biased angular quadrature sets or last collided source calculation) as well as DOORS in order to obtain similar results as those with MCNP, though Attila consumes much more time and memory than DOORS.

Journal Articles

Use of CAD generated geometry data in Monte Carlo transport calculations for ITER

Fischer, U.*; Iida, Hiromasa; Li, Y.*; Loughlin, M.*; Sato, Satoshi; Serikov, A.*; Tsige-Tamirat, H.*; Tautges, T.*; Wilson, P. P.*; Wu, Y.*

Fusion Science and Technology, 56(2), p.702 - 709, 2009/08

 Times Cited Count:12 Percentile:30.48(Nuclear Science & Technology)

Several approaches have been recently developed to make available CAD geometry data for Monte Carlo calculations with the MCNP code. Among these are conversion tools for the automatic generation of geometry models in MCNP representation such as MCAM of China, McCad of Germany, and GEOMIT of JAEA, as well as the direct DAG-MCNPX approach developed by USA. An extensive benchmark exercise has been conducted on ITER between 2005 and 2007 with the objective to test and validate the different approaches and thereby check the maturity level for ITER design applications. The exercise encompassed the generation of a dedicated neutronics CATIA model based on available engineering CAD design data, the conversion into MCNP geometry, the verification of the converted models, and a number of calculations to compare the different approaches with regard to the performance and the validity of the results obtained. The paper briefly reviews the different approaches and provides a detailed description of the ITER benchmark effort, its results and conclusions. As a key issue, the recommendations are discussed that need to be followed when generating a neutronics CAD model for ITER design calculations. This is considered essential since the ITER quality assurance requirements will request the consistency of the analysis models and the underlying engineering CAD models.

Journal Articles

ITER nuclear analysis strategy and requirements

Loughlin, M. J.*; Batistoni, P.*; Konno, Chikara; Fischer, U.*; Iida, Hiromasa; Petrizzi, L.*; Polunovskiy, E.*; Sawan, M.*; Wilson, P.*; Wu, Y.*

Fusion Science and Technology, 56(2), p.566 - 572, 2009/08

 Times Cited Count:33 Percentile:6.73(Nuclear Science & Technology)

It is envisaged that ITER should produce as much as 700 MW of fusion power. This equates to the production of 2.48$$times$$10$$^{20}$$ 14MeV neutrons/s which will give an uncollided flux at the first wall of approximately 4$$times$$10$$^{13}$$ n/cm$$^{2}$$/s and a total with the addition of the collided to some 10$$^{14}$$ n/cm$$^{2}$$/s. ITER is therefore a significant nuclear facility and it is essential that an efficient and coherent strategy for nuclear analysis is in place. This paper reviews the status of the methods applied to date and recommends the future strategy which ITER should adopt to address the continuing requirements and responsibilities. This is done by consideration of the application of radiation transport codes, the creation of suitable models, developments in information technology, and the management tools which will be required. Areas in which new codes and techniques need to be developed will be identified.

Journal Articles

D-T neutron streaming experiment simulating narrow gaps in ITER equatorial port

Ochiai, Kentaro; Sato, Satoshi; Wada, Masayuki*; Iida, Hiromasa; Takakura, Kosuke; Kutsukake, Chuzo; Tanaka, Shigeru; Abe, Yuichi; Konno, Chikara

Fusion Engineering and Design, 83(10-12), p.1725 - 1728, 2008/12

 Times Cited Count:1 Percentile:88.07(Nuclear Science & Technology)

Under the ITER/ITA task, we have conducted the neutron streaming experiment simulating narrow and deep gaps at boundaries between ITER vacuum vessel and equatorial port plugs. Micro fission chambers and some activation foils were utilized to measure fission rates and reaction rates to evaluate the relative fast and slow neutron fluences along the gap in the experimental assembly. The MCNP4C, TORT and Attila codes were used for the experimental analysis. From comparing our measurements and calculations, the following facts were found: (1) In case of a such narrow and deep gap structure, the calculation with MCNP, TORT and ATTILA codes and FENDL-2.1 is sufficient to predict fast neutron field inside the gap.: (2) Angular quadrature set of upward biased U315 and last collided source calculation on TORT and Attila were very important technique for accurate estimation of neutron transport.

Journal Articles

Present status of investigations on ITER neutron streaming

Ochiai, Kentaro; Iida, Hiromasa; Sato, Satoshi; Takakura, Kosuke; Konno, Chikara

Purazuma, Kaku Yugo Gakkai-Shi, 84(9), p.594 - 599, 2008/09

no abstracts in English

JAEA Reports

Solution of large underestimation problem in the Monte Carlo calculation with hard biasing; In case with geometry input data created by CAD/MCNP automatic converter

Iida, Hiromasa; Kawasaki, Nobuo*; Konno, Chikara; Sato, Satoshi; Seki, Akiyuki

JAEA-Research 2008-050, 26 Pages, 2008/04

JAEA-Research-2008-050.pdf:1.98MB

An inconvenient experience was encountered, in which we have different answers depending on applied weight window values, in the nuclear analysis of the benchmark problem for CAD/MCNP interface programs, being developed under the ITER R&D task. Biasing can enhance calculation speed, but should not give different answers. Mechanism of this large underestimation is clarified. It is caused by the combination of the following two facts; (1) When one of particles in a history has got lost, MCNP cancels all tallies calculated during the history and all banked particles are thrown away (never tracked). (2) When we have distributed micro geometry errors in input data, important histories, which give significant contribution to tallies, will have many splitting and have "lost particle" with higher probability in the case of hard biasing. These two facts lead to selective canceling of important histories. An attempt to eliminate this inconvenience has been made, by modifying the subroutine "hstory" of MCNP. The modification has been done very successfully and eliminated the large underestimation, giving the same answer independently from applied weight window values.

Journal Articles

Development of CAD/MCNP interface program prototype for fusion reactor nuclear analysis

Sato, Satoshi; Iida, Hiromasa; Nishitani, Takeo

Fusion Engineering and Design, 81(23-24), p.2767 - 2772, 2006/11

 Times Cited Count:12 Percentile:30.24(Nuclear Science & Technology)

no abstracts in English

Journal Articles

A New developed interface for CAD/MCNP data conversion

Shaaban, N.*; Masuda, Fukuzo*; Nasif, H.*; Yamada, Masao*; Sawamura, Hidenori*; Morota, Hidetsugu*; Sato, Satoshi; Iida, Hiromasa; Nishitani, Takeo

Proceedings of 14th International Conference on Nuclear Engineering (ICONE-14) (CD-ROM), 7 Pages, 2006/07

no abstracts in English

Journal Articles

Control and instrumentation for the ITER magnet system

Yoshida, Kiyoshi; Takahashi, Yoshikazu; Iida, Hiromasa

IEEE Transactions on Applied Superconductivity, 16(2), p.775 - 778, 2006/06

 Times Cited Count:1 Percentile:86.75(Engineering, Electrical & Electronic)

The ITER superconducting coil system consists of 18 TF coils, 6 PF coils, 6 CS modules, 18 Correction Coils and their feeders. An extensive measurement and control system is required to monitor and to control these coils and feeders for safety and optimal operational availability. For each coil, both current and helium are supplied from external systems and are controlled from a central control system that manages flow distribution at each cooling pass to smooth the cryoplant loads by a virtual model of the coil thermo-hydraulic system. Quench detection is provided as stand alone system. Monitoring of the electric insulation system inside the coils is performed to detect incipient problems before serious damage. The ITER will procure directly all sensors, wires, electrical insulation breaks and cryogenic components for all the coils and feeders to a common specification. This will avoid duplication of qualification work and guarantee a common interface. This paper introduces the requirements and specifications of the control and instrumentation for the ITER magnet system.

JAEA Reports

Analyses of heat load in ITER NBI duct and neutron streaming through pressure relief line

Sato, Satoshi; Yamauchi, Michinori; Nishitani, Takeo; Ioki, Kimihiro; Iida, Hiromasa; Kataoka, Yoshiyuki

JAEA-Technology 2006-032, 91 Pages, 2006/03

JAEA-Technology-2006-032.pdf:12.8MB

no abstracts in English

Journal Articles

Shielding design of the ITER NBI Duct for nuclear and bremsstrahlung radiation

Sato, Satoshi; Iida, Hiromasa; Yamauchi, Michinori*; Nishitani, Takeo

Radiation Protection Dosimetry, 116(1-4), p.28 - 31, 2005/12

 Times Cited Count:2 Percentile:79.56(Environmental Sciences)

no abstracts in English

Journal Articles

Nuclear analyses of some key aspects of the ITER design with Monte Carlo codes

Iida, Hiromasa; Petrizzi, L.*; Khripunov, V.*; Federici, G.*; Polunovskiy, E.*

Fusion Engineering and Design, 75(1-4), p.133 - 139, 2005/11

The design of the ITER machine was presented in 2001. A nuclear analysis has been performed on ITER by means of the most detailed models and the best assessed nuclear data and codes. As the construction phase of ITER is approaching, the design of the main components has been optimized/finalized and several minor design changes/optimizations have been made, which required refined calculations to confirm that nuclear design requirements are met. Some of the proposed design changes have been made to mitigate critical radiation shielding problems. This paper reviews some of the most recent neutronic work with emphasis on critical nuclear responses in the TF coil inboard legs and vacuum vessel related to design modifications made to the blanket modules and vacuum vessel.

Journal Articles

Evaluation of shutdown $$gamma$$-ray dose rates around the duct penetration by three-dimensional Monte Carlo decay $$gamma$$-ray transport calculation with variance reduction method

Sato, Satoshi; Iida, Hiromasa; Nishitani, Takeo

Journal of Nuclear Science and Technology, 39(11), p.1237 - 1246, 2002/11

 Times Cited Count:23 Percentile:16.41(Nuclear Science & Technology)

no abstracts in English

Journal Articles

ITER engineering design

Shimomura, Yasuo; Tsunematsu, Toshihide; Yamamoto, Shin; Maruyama, So; Mizoguchi, Tadanori*; Takahashi, Yoshikazu; Yoshida, Kiyoshi; Kitamura, Kazunori*; Ioki, Kimihiro*; Inoue, Takashi; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 78(Suppl.), 224 Pages, 2002/01

no abstracts in English

Journal Articles

Radiation shielding for ITER to allow for hands-on maintenance inside the cryostat

Iida, Hiromasa; Valenza, D.*; Plenteda, R.*; Santoro, R. T.*; Dietz, J.*

Journal of Nuclear Science and Technology, 37(Suppl.1), p.235 - 242, 2000/03

no abstracts in English

66 (Records 1-20 displayed on this page)