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Journal Articles

Study on dismantling scenario for large equipment in decommissioning of nuclear facilities; Utilization of validation result of applicability of project management data evaluation code to decommissioning project of FUGEN

Shibahara, Yuji; Usui, Hideo; Izumo, Sari; Izumi, Masanori; Tezuka, Masashi; Morishita, Yoshitsugu; Kiyota, Shiko; Tachibana, Mitsuo

Nippon Genshiryoku Gakkai Wabun Rombunshi, 12(3), p.197 - 210, 2013/09

As the first step of the applicability inspection of PRODIA Code for dismantling activities in the decommissioning of FUGEN, manpower needs for dismantling activities in FUGEN conducted in 2008 were calculated with conventional calculation formulas which were made by data obtained from JPDR decommissioning program. Since the conventional calculation formula for dismantling of feedwater heater has no applicability, the new calculation formula was constructed by reflecting the work description of dismantling of feedwater heater in FUGEN. It was found that the calculation results with this new formula showed the good agreement with the actual data both of 3rd feedwater heater and 4th one. Based on this discussion, some case studies for dismantling of feedwater heater were conducted.

JAEA Reports

Conceptual design of multipurpose compact research reactor; Annual report FY2011

Watahiki, Shunsuke; Hanakawa, Hiroki; Imaizumi, Tomomi; Nagata, Hiroshi; Ide, Hiroshi; Komukai, Bunsaku; Kimura, Nobuaki; Miyauchi, Masaru; Ito, Masayasu; Nishikata, Kaori; et al.

JAEA-Technology 2013-021, 43 Pages, 2013/07

JAEA-Technology-2013-021.pdf:5.12MB

The number of research reactors in the world is decreasing because of their aging. On the other hand, the necessity of research reactor, which is used for human resources development, progress of the science and technology, industrial use and safety research is increasing for the countries which are planning to introduce the nuclear power plants. From above background, the Neutron Irradiation and Testing Reactor Center began to discuss a basic concept of Multipurpose Compact Research Reactor (MCRR) for education and training, etc., on 2010 to 2012. This activity is also expected to contribute to design tool improvement and human resource development in the center. In 2011, design study of reactor core, irradiation facilities with high versatility and practicality, and hot laboratory equipment for the production of Mo-99 was carried out. As the result of design study of reactor core, subcriticality and operation time of the reactor in consideration of an irradiation capsule, and about the transient response of the reactor to the reactivity disturbance during automatic control operation, it was possible to do automatic operation of MCRR, was confirmed. As the result of design study of irradiation facilities, it was confirmed that the implementation of an efficient mass production radioisotope Mo-99 can be expected. As the result of design study with hot laboratory facilities, Mo-99 production, RI export devised considered cell and facilities for exporting the specimens quickly was designed.

Journal Articles

Quantum fluctuation and vibrational dynamics of aqueous Cu$$^+$$ and Ag$$^+$$ clusters

Koizumi, Akihito*; Tachikawa, Masanori*; Shiga, Motoyuki

Chemical Physics, 419, p.44 - 49, 2013/06

 Times Cited Count:1 Percentile:95.95(Chemistry, Physical)

The structures and infrared spectra of Ag$$^+$$(H$$_2$$O)$$_n$$ ($$n$$ = 1-4) and Cu$$^+$$ (H$$_2$$O) are studied by $$on$$-$$the$$-$$fly$$ $$ab$$ $$initio$$ MD, $$ab$$ $$initio$$ PIMD, and $$ab$$ $$initio$$ RPMD simulations. It is found that the anharmonicity due to nuclear quantum and thermal effects acts differently depending on the system as well as the type of vibrational mode. In the low-frequency region, the spectra become a broad band as the cluster size increases due to the complex mode couplings, which is qualitatively different from the harmonic spectra. In contrast, the HOH bending modes are systematically red-shifted by a small amount due to the anharmonicity. The OH stretching modes are found to be also red-shifted, but the amount of shift is more dependent on the system. Consequently, these effects cannot be described by unique scaling of harmonic frequencies.

JAEA Reports

Preliminary accident analysis for a conceptual design of a 10 MW multi-purpose research reactor

Park, C.; Tanimoto, Masataka; Imaizumi, Tomomi; Miyauchi, Masaru; Ito, Masayasu; Kaminaga, Masanori

JAEA-Technology 2012-039, 87 Pages, 2013/01

JAEA-Technology-2012-039.pdf:3.55MB

Preliminary accident analysis has been carried out for a LOFA (Loss of Flow Accident) and RIAs (Reactivity Insertion Accidents) of the conceptual 10 MW MRR (multi-purpose research reactor) under design study by using the RELAP5/MOD3 code in order to provide the preliminary evaluation of safety margin as well as the intuitions to the design of the MRR. Input and modeling for the RELAP5/MOD3 simulations have also been described. The analysis results indicate that the concept of the MRR is feasible with practical safety margins. The same events have been also analyzed by using the PARET/ANL and the EUREKA-2/RR codes to compare the codes suitability, which have been widely used for the analysis of research reactors. Same geometric and modeling data used for the RELAP5/MOD3 have been used as long as they correspond to each code's input requirements. The three codes show the same or similar overall trends for the events analyzed, but show a small difference in a specific condition.

JAEA Reports

Conceptual design of multipurpose compact research reactor; Annual report FY2010 (Joint research)

Imaizumi, Tomomi; Miyauchi, Masaru; Ito, Masayasu; Watahiki, Shunsuke; Nagata, Hiroshi; Hanakawa, Hiroki; Naka, Michihiro; Kawamata, Kazuo; Yamaura, Takayuki; Ide, Hiroshi; et al.

JAEA-Technology 2011-031, 123 Pages, 2012/01

JAEA-Technology-2011-031.pdf:16.08MB

The number of research reactors in the world is decreasing because of their aging. However, the planning to introduce the nuclear power plants is increasing in Asian countries. In these Asian countries, the key issue is the human resource development for operation and management of nuclear power plants after constructed them, and also the necessity of research reactor, which is used for lifetime extension of LWRs, progress of the science and technology, expansion of industry use, human resources training and so on, is increasing. From above backgrounds, the Neutron Irradiation and Testing Reactor Center began to discuss basic concept of a multipurpose low-power research reactor for education and training, etc. This design study is expected to contribute not only to design tool improvement and human resources development in the Neutron Irradiation and Testing Reactor Center but also to maintain and upgrade the technology on research reactors in nuclear power-related companies. This report treats the activities of the working group from July 2010 to June 2011 on the multipurpose low-power research reactor in the Neutron Irradiation and Testing Reactor Center and nuclear power-related companies.

Journal Articles

Ab initio path integral simulation of AgOH(H$$_2$$O)

Koizumi, Akihito*; Suzuki, Kimichi*; Shiga, Motoyuki; Tachikawa, Masanori*

International Journal of Quantum Chemistry, 112(1), p.136 - 139, 2012/01

 Percentile:100(Chemistry, Physical)

Ab initio path integral molecular dynamics simulation of MOH(H$$_2$$O) (M= Cu, Ag, and Au) clusters has been carried out to analyze how the hydrogen-bonded proton can be affected by the counter noble metal cation. The CuOH(H$$_2$$O) cluster forms no hydrogen bonded structure even for the static equilibrium structures. Contrary to our previous paper of hydrated alkali metal hydroxide clusters, proton transferred distribution was not observed because of the high potential barrier heights of MOH(H$$_2$$O).

Journal Articles

Nuclear quantum effect on the hydrogen-bonded structure of guanine-cytosine pair

Daido, Masashi*; Koizumi, Akihito*; Shiga, Motoyuki; Tachikawa, Masanori*

Theoretical Chemistry Accounts, 130(2-3), p.385 - 391, 2011/10

 Times Cited Count:6 Percentile:80.55(Chemistry, Physical)

The structure of Watson-Crick type guanine-cytosine (G-C) base pair has been studied by classical hybrid Monte Carlo (HMC) and quantum path integral hybrid Monte Carlo (PIHMC) simulations on the semiempirical potential energy surface. For the three NH$$cdots$$X hydrogen-bonded moieties, the intramolecular NH bonds are found systematically longer while the H$$cdots$$X distance shorter in the PIHMC simulation than in the HMC simulation. We found that the hydrogen bonded length N$$cdots$$X correlates with the H$$cdots$$X distance, but not with the NH distance. A correlation is also between the neighboring hydrogen bonds in the G-C base pair.

JAEA Reports

Results of the environmental radiation monitoring following the accident at the Fukushima Daiichi Nuclear Power Plant; Interim report (Ambient radiation dose rate, radioactivity concentration in the air and radioactivity concentration in the fallout)

Furuta, Sadaaki; Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Imaizumi, Kenji; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Mizutani, Tomoko; Morisawa, Masato; et al.

JAEA-Review 2011-035, 89 Pages, 2011/08

JAEA-Review-2011-035.pdf:2.97MB

As a correspondence to the accident at the Fukushima Daiichi Nuclear Power Plant, the environmental radiation monitoring was performed at the Nuclear Fuel Cycle Engineering Laboratories, JAEA. This report presented the measurement results of ambient radiation dose rate, radioactivity concentration in the air and radioactivity concentration in fallout and meteorological observation result until May 31, 2011. The ambient radiation dose rate increased, with the peak dose rate of several thousand nGy/h at 7 o'clock in March 15, at 5 o'clock in March 16, and at 4 o'clock in March 21. The variation on the radioactivity concentration in the air and in fallout showed the almost same tendency as that of the dose rate. The concentration ratio of I-131/Cs-137 in the air increased to about 100. The dose was estimated resulting from internal exposure due to inhalation.

JAEA Reports

Document collection of the 22nd Technical Special Committee on Fugen Decommissioning

Kutsuna, Hideki; Matsumori, Akira*; Izumi, Masanori; Hayashi, Hirokazu; Higashiura, Norikazu

JAEA-Review 2011-025, 43 Pages, 2011/07

JAEA-Review-2011-025.pdf:2.84MB

In planning and carrying out our decommissioning technical development, "Technical special committee on Fugen decommissioning", which consists of the members well-informed, is established, aiming to make good use of Fugen as a place for technological development which is opened inside and outside the country, as the central point in the energy research and development base making project of Fukui prefecture, and to utilize the outcome in our decommissioning to the technical development effectively. This report compiles presentation materials "Current Situation of Fugen Decommissioning", "Radioactive Corrosion Products (CP) Decontamination Experiment with Heavy Water System Equipment", "Application of management data evaluation system to Fugen", "Preparatory Situation for Operation of Clearance System" of the 22nd Technical special committee on Fugen decommissioning which held on September 14, 2010.

JAEA Reports

Study on applicability of evaluation model of manpower needs for dismantling of equipments in FUGEN, 2; Preparation and clean-up process in 3rd/4th feedwater heater room

Shibahara, Yuji; Tachibana, Mitsuo; Izumi, Masanori; Nanko, Takashi

JAEA-Technology 2011-010, 44 Pages, 2011/06

JAEA-Technology-2011-010.pdf:2.43MB

Manpower needs for the preparation and clean-up process on the dismantling of equipments in FUGEN 3rd/4th feedwater heater room conducted in 2008 was calculated with the management data evaluation system: PRODIA Code, and it was inspected whether the conventional evaluation model had the applicability for large nuclear facilities such as FUGEN or not. It was confirmed that the conventional evaluation model had no applicability for FUGEN causing by the difference in the plant scale between JPDR and FUGEN bringing the expanding of working area. The difference between the actual data and the calculated value was improved by the reviewing of the evaluation model, and this reviewing process also brought the new evaluation model.

Journal Articles

A Concerted mechanism between proton transfer of Zundel anion and displacement of counter cation

Koizumi, Akihito*; Suzuki, Kimichi*; Shiga, Motoyuki; Tachikawa, Masanori*

Journal of Chemical Physics, 134(3), p.031101_1 - 031101_3, 2011/01

 Times Cited Count:12 Percentile:50.04(Chemistry, Physical)

${it Ab initio}$ path integral molecular dynamics simulation of M$$^+$$H$$_3$$O$$_2^-$$ (M = Li, Na, and K) has been carried out to study how the structure and dynamics of low-barrier hydrogen-bonded Zundel anion, H$$_3$$O$$_2^-$$, can be affected by the counter alkali metal cation, M$$^+$$. Our simulation predicts that the quantum proton transfer in Zundel anion can be strongly coupled to the motion of counter cation located nearby. A smaller cation can induce larger structural distortion of the Zundel anion fragment making the proton transfer barrier higher, and hence lowers the vibration excitation energy. It is also argued that a large H/D isotope effect is present.

JAEA Reports

Study on applicability of evaluation model of manpower needs for dismantling of equipments in FUGEN, 1; Dismantling process in 3rd/4th feedwater heater room

Shibahara, Yuji; Tachibana, Mitsuo; Ishigami, Tsutomu; Izumi, Masanori; Nanko, Takashi

JAEA-Technology 2010-033, 42 Pages, 2010/10

JAEA-Technology-2010-033.pdf:1.02MB

Manpower needs for the dismantling process in FUGEN 3rd/4th feedwater heater room was calculated with the evaluation system (PRODIA Code), and it was inspected whether the conventional evaluation model had applicability for FUGEN or not. It was confirmed that the conventional evaluation model for feedwater heater had no applicability. In comparison of the calculated value with the actual data, we found two difference: (1) the evaluated manpower were significantly larger than the actual data, (2) the manpower need for the dismantling of 3rd feedwater heater was twice larger than that of 4th feedwater heater, though these equipments were almost same weight. It was found that these were brought (1) by the difference in the work descriptions of dismantling between JPDR and FUGEN, and (2) by that in the cutting number between 3rd feedwater heater and 4th one. The manpower needs for the dismantling of both feedwater heaters were calculated with a new calculation equation reflecting the descriptions of dismantling, and it was found that these results showed the good agreement with the actual data.

Journal Articles

Study on evaluation models of management data for decommissioning of FUGEN

Shibahara, Yuji; Izumi, Masanori; Nanko, Takashi; Tachibana, Mitsuo; Ishigami, Tsutomu

Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.347 - 353, 2010/10

Journal Articles

Development of a tracking method for augmented reality applied to NPP maintenance work and its experimental evaluation

Bian, Z.*; Ishii, Hirotake*; Shimoda, Hiroshi*; Yoshikawa, Hidekazu*; Morishita, Yoshitsugu; Kanehira, Yoshiki; Izumi, Masanori

IEICE Transactions on Information and Systems, E90-D(6), p.963 - 974, 2007/06

 Times Cited Count:3 Percentile:68.28(Computer Science, Information Systems)

This study designed linecode marker, a new type of paper-based marker and proposed recognition, tracking algorithm for it in order to resolve these problems. In comparison of the conventional paper-based markers, such as square markers, circle markers, the linecode marker is not only just easier to set up in complex industrial environment, but also makes it possible to use AR in industrial plant. In order to evaluate the tracking accuracy, trackable distance of the proposed tracking method, an evaluation experiment was conducted in a large room. The experiment results show that: comparing with traditional marker-based tracking method, tracking possible distance extends extremely; tracking accuracy improved to a level of 20cm in 10m distance.

Journal Articles

Development of Decommissioning Engineering support system for The Fugen NPS; Development of support system during actual dismantlement works

Izumi, Masanori

Proceedings of 13th International Conference on Nuclear Engineering (ICONE-13) (CD-ROM), P. 353, 2005/05

Fugen have been developing Decommissioning Engineering Support system (DEXUS)aimed at planning optimal dismantlement process and carrying out dismantlement work safely and correctly. DEXUS consists of "Decommissioning Plan Support System" and "Dismantlement Support system". We reported about the former sysyem , so we intend to report about the latter system. The main object of dismantlement support system is to ensure safety for wokers collectdismantlement result data and manage genrated wastes during the actual dismatlement works. Now we are develpoing three subsystems such as "Worksite visualization system","Collecting dismantlement resultsystem" and "Management generated Waste system".

JAEA Reports

The VRdose Software System: - User Manual, Report and Design Documentation for R5-

Iguchi, Yukihiro; Knehira, Yoshiki; Izumi, Masanori; Fujita, Toru*; Oya, Kiyomi*

JNC-TN3520 2004-001, 172 Pages, 2004/03

JNC-TN3520-2004-001.pdf:11.04MB

In the VRdose R5 version the connection with the dynamic radiation evaluation system (DRES) was the main task. DRES can calculate the dose rate field of the Fugen plant in detail. By inserting special markers into the scenario, VRdose tells DRES what changes have been made to the model. The changes are about objects that are inserted, removed, cut or moved. DRES will then calculate new dose rate fields reflecting these changes. To minimize the calculation needed for DRES, VRdose can provide a volume enclosing only the area of interest for a given scenario and give the resolution of the calculation in all axes. In addition to the DRES connection, version R5 retrieves information about the objects in the model from the Fugen object database. Among the large amount of information available, are size, weight and surface contamination of co-60 used. The wizard uses the size and weight information in the calculation of the man-work required. The surface contamination is used in a new feature that colorizes the objects after the contamination value. This makes it easier for workers to become aware of the contamination of pipes and pumps etc. R5 has been internationalized on all menus, buttons, messages and other text. VRdose can therefore be translated into any desired language. A feasibility study has been made into using Japanese characters in names and properties in the scenario. Printing of the 3D view has been implemented, which is useful for documenting. The scenario can also be printed, both as a graphical representation and in a textual report format. Other functionality that can be mentioned is output from the wizard to Cosmard and the saving of viewpoints. The manikins wear different protection masks and in version R5 the efficiency of the protection can be changed for each nuclide. Several other minor changes have been made, such as the ability to switch between extern dose and nuclide intake in the dose graph panels.

Journal Articles

Manufacturing and maintenance technologies developed for a thick-wall structure of the ITER vacuum vessel

Onozuka, Masanori*; Alfile, J. P.*; Aubert, P.*; Dagenais, J.-F.*; Grebennikov, D.*; Ioki, Kimihiro*; Jones, L.*; Koizumi, Koichi; Krylov, V.*; Maslakowski, J.*; et al.

Fusion Engineering and Design, 55(4), p.397 - 410, 2001/09

 Times Cited Count:17 Percentile:20.82

Development of welding, cutting and non-destructive testing (NDT) techniques, and development of remotized systems, have been conducted for on-site manufacturing and maintenance of the thick wall structure of the ITER vacuum vessel (VV). Conventional techniques, including TIG (tungsten inert gas) welding, plasma cutting and ultrasonic inspection, have been improved and optimized for the application to thick austenitic stainless steel plates. In addition, advanced methods have been investigated including reduced-pressure electron-beam and multi-pass NdYAG (neodymium-doped yttrium aluminum garnet) laser welding, NdYAG laser cutting, and EMAT (electro-magnetic acoustic transducer) inspection to improve cost and technical performance. Two types of remotized systems with different payloads have been investigated and one of them has been fabricated and demonstrated in field joint welding, cutting, and NDT tests on test mockups and full-scale ITER VV sector models. The progress and results of this development to date provide a high level of confidence that the manufacturing and maintenance of the ITER VV is feasible.

Journal Articles

Progress and achievements on the R&D activities for ITER vacuum vessel

Nakahira, Masataka; Takahashi, Hiroyuki*; Koizumi, Koichi; Onozuka, Masanori*; Ioki, Kimihiro*

Nuclear Fusion, 41(4), p.375 - 380, 2001/04

 Times Cited Count:4 Percentile:82.6(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Evaluation of welding deformation on ITER vacuum vessel

Nakahira, Masataka; Takahashi, Hiroyuki*; Inoue, O.*; Koizumi, Koichi; Shibanuma, Kiyoshi; Tada, Eisuke; Onozuka, Masanori*; Ioki, Kimihiro*

Proceedings of the 18th IEEE/NPSS Symposium on Fusion Engineering (SOFE '99), p.245 - 248, 1999/00

no abstracts in English

Journal Articles

Fabrication and assembly of full-scale sector models for ITER vacuum vessel

Koizumi, Koichi; Nakahira, Masataka; Oka, Kiyoshi; *; Takahashi, Hiroyuki*; Tada, Eisuke; Ioki, Kimihiro*; Johnson, G.*; Onozuka, Masanori*; Y.Utin*; et al.

Fusion Technology, 34(3), p.586 - 590, 1998/11

no abstracts in English

53 (Records 1-20 displayed on this page)