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Journal Articles

Neutron moderation, 1; Research reactor as neutron source

Arai, Masaji

Hamon, 28(2), p.99 - 102, 2018/05

A thermal neutron reactor operates by the fission of uranium, a nuclear reaction which produces neutrons of energies in the range of MeV. This is far too high an energy to be useful for neutron scattering experiments. Therefore in a research reactor which has neutron beam utilization there are moderators arranged around the primary source to slow down the source neutrons to useful energies. Additionally almost major research reactors include at least one cold neutron source, a special moderator maintained at cryogenic temperature, where neutrons can equilibrate to lower average energies.

Journal Articles

Design and burn-up analyses of new type holder for silicon neutron transmutation doping

Komeda, Masao; Arai, Masaji; Tamai, Kazuo*; Kawasaki, Kozo*

Applied Radiation and Isotopes, 113, p.60 - 65, 2016/07

 Times Cited Count:2 Percentile:70.56(Chemistry, Inorganic & Nuclear)

We designed and fabricated a new type holder that achieved uniform doping under long-term use at JRR-3. The new type holder uses an aluminum alloy and B$$_{4}$$C particles as filter materials to ensure uniform vertical flux distribution. Although the amount of filter material decreases with long-term use, it was found that the doping distribution did not change by much until 800 h. The lifetime of the new type holder (of the order of hundreds of hours) depends mainly on the amount of trapped radioactive isotopes. This indicates that the decrease in filtering ability over the filter's lifetime is not significant. The filtering ability remains stable for a long time, and the difference in the vertical doping distribution is 1.08 at 1600 h and 1.18 at 4000 h. The irradiation efficiency is expected to increase by 1.7 times when using the new type holder.

Journal Articles

Status of JRR-3 after Great East Japan Earthquake

Arai, Masaji; Wada, Shigeru; Murayama, Yoji

Proceedings of International Topical Meeting on Research Reactor Fuel Management and Meeting of the International Group on Reactor Research (RRFM/IGORR 2016) (Internet), p.403 - 408, 2016/03

In response to the accident at Fukushima Daiichi NPS, the new safety standards for research and test reactor facilities came into force on December 18, 2013. The evaluation of natural disasters and prevention of spread of accidents beyond design basis mainly were enhanced in the standards. We have completed the necessary checks and assessments, and submitted an application for reviewing if JRR-3 complies with the new standards to the Nuclear Regulation Authority on September 26, 2014.

Journal Articles

The Investigation of the new multipurpose research reactor succeeding to JRR-3

Takino, Kazuo; Arai, Masaji; Murayama, Yoji

Proceedings of International Topical Meeting on Research Reactor Fuel Management and Meeting of the International Group on Reactor Research (RRFM/IGORR 2016) (Internet), p.667 - 676, 2016/03

Our working group has started to investigate basic concepts of the new research reactor which foresaw twenty years later. The aim of this project is to build up the design of new multipurpose research reactor which is constructed instead of JRR-3 for utilization of the neutron beam, irradiation, training and so on.

JAEA Reports

Developments of high-performance moderator vessel for JRR-3 cold neutron source

Arai, Masaji; Tamura, Itaru; Hazawa, Tomoya

JAEA-Technology 2015-010, 52 Pages, 2015/05

JAEA-Technology-2015-010.pdf:7.11MB

In the Department of Research Reactor and Tandem Accelerator, developments of high-performance CNS moderator vessel that can produce cold neutron intensity about two times higher compared to the existing vessel have been performed in the second medium term plans. We compiled this report about the technological development to solve several problems with the design and manufacture of new vessel. In the present study, design strength evaluation, mockup test, simulation for thermo-fluid dynamics of the liquid hydrogen and strength evaluation of the different-material-bonding were studied. By these evaluation results, we verified that the developed new vessel can be applied to CNS moderator vessel of JRR-3.

JAEA Reports

Development of breast cancer irradiation technique for BNCT at JRR-4

Nakamura, Takemi; Horiguchi, Hironori; Yanagie, Hironobu*; Arai, Masaji

JAEA-Technology 2014-016, 61 Pages, 2014/06

JAEA-Technology-2014-016.pdf:30.48MB

In the department of research reactor and tandem accelerator, developments of irradiation technique with application enlargement for breast cancer on BNCT have been performed in the second medium term plans. We compiled this report about the technological development to solve several problems with the irradiation of breast cancer in the medical irradiation facility of JRR-4. In the present study, design fabrication of a collimator for breast cancer, dose evaluation analysis by clinical model, investigation of dose enhancement at deeper region and investigation of fixing method for breast cancer irradiation were studied. By these evaluation results, we verified that the developed breast cancer irradiation technique can be applied to BNCT medical irradiation of JRR-4. These results are expected to be able to contribute to breast cancer irradiation techniques of other reactor-based BNCT and future accelerator-based BNCT.

Journal Articles

Current status of JRR-3

Kinase, Masami; Arai, Masaji; Maruo, Takeshi

Proceedings of Joint IGORR 2013 & IAEA Technical Meeting (Internet), 12 Pages, 2013/10

JRR-3 at the Tokai-Shirakata site of JAEA was in its regular maintenance period, when the Great East Japan Earthquake took place on 11th March 2011. The reactor building with the solid foundations and the equipment important to safety survived the earthquake without serious damage, and no radioactive leakage has been occurred. Recovery works, check and test to confirm the integrity of all components and structures, and seismic assessment necessary for proving that the seismic loads which worked on a structure or component by the earthquake accommodated within its allowable stress have been carried out. After our recovery works and verification of the integrity of JRR-3, we confirmed that the integrity is ensured, and then reported the fact to the regulatory body. As another topic, the regulatory body will introduce new regulatory requirements for research reactors. Now, JRR-3 considers applying the new requirements for restart. This paper presents the current status of JRR-3 including the recovery works, seismic assessment and new regulatory requirements.

JAEA Reports

Criticality analyses of the JRF-90Y-950K package for research reactors; Under consideration of deformation for oblique drops onto a bar

Araki, Masaaki; Kato, Tomoaki; Arai, Masaji

JAEA-Technology 2010-015, 35 Pages, 2010/06

JAEA-Technology-2010-015.pdf:1.04MB

Research reactor JRR-3 is a light water moderated and cooled pool type research reactor using low enriched uranium-silicon-aluminum-dispersion-type fuel. French Competent Authority (FCA) required that the criticality safety of the JRF-90Y-950K package is maintained even if it is deformed under oblique drops onto a bar. Criticality analyses of the JRF-90Y-950K package were carried out for the transport of JRR-3, JRR-4 or JMTR fuel. The results show that criticality safety is kept even if it is deformed under oblique drops onto a bar.

Journal Articles

Conceptual study for the hollow core of a research reactor

Komeda, Masao; Arai, Masaji; Sagawa, Hisashi; Kusunoki, Tsuyoshi

Proceedings of 12th International Group on Research Reactors (12th IGORR) (USB Flash Drive), 9 Pages, 2009/10

Oral presentation

Strength evaluation of JRR-3 high-performance moderator vessel for cold neutron beam, 2

Arai, Masaji; Tamura, Itaru; Komeda, Masao; Mineshima, Hiromi

no journal, , 

Existing moderator vessel for JRR-3 cold neutron source (CNS) facility is ovoid shape with stainless steel. In order to increase the intensity of cold neutron beam, we are developing high-performance moderator vessel which is new boat-bottom shape with aluminum alloy. The strength analysis of new moderator vessel has been evaluated by nonlinear finite element analysis code ABAQUS bellow maximum allowable working pressure, and the results met the technical criterion required by the national law. The validity of a result was confirmed by the hydraulic pressure test used by the test moderator vessel. Additionally, strength analysis in 1.5 times pressure (internal pressure about 0.675 MPa) of maximum allowable working pressure was carried out for the pressure proof test of the technical criterion and the soundness of new moderator vessel was newly studied.

Oral presentation

Calculation for transportation efficiency improvement of the neutron straight guide section of C3 cold neutron guides at JRR-3, 1

Tamura, Itaru; Arai, Masaji; Komeda, Masao; Sagawa, Hisashi

no journal, , 

no abstracts in English

Oral presentation

Heat evaluation of JRR-3 high-performance moderator vessel for cold neutron beam

Arai, Masaji; Tamura, Itaru; Komeda, Masao; Mineshima, Hiromi

no journal, , 

no abstracts in English

Oral presentation

Improvement of neutron transportation of C3 cold neutron guide tube in the JRR-3, 2

Tamura, Itaru; Arai, Masaji; Nagahori, Kazuhisa; Hazawa, Tomoya; Sagawa, Hisashi; Wada, Shigeru

no journal, , 

no abstracts in English

Oral presentation

Improvement of neutron transportation efficiency on the cold neutron guide C3 by using supermirrors in the JRR-3

Tamura, Itaru; Arai, Masaji; Sagawa, Hisashi

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

Development of JRR-3 high-performance moderator vessel for cold neutron beam

Arai, Masaji; Tamura, Itaru; Wada, Shigeru

no journal, , 

The moderator vessel with neutron slowing-down, e.g. the spherical, ring-like annular or crescent shape, has been used recently in CNS. However, the JRR-3 CNS still has the same flat shape vessel as the ORPHEE's old type vessel, which was made from stainless steel. The improvement of JRR-3's vessel by optimizing the shape and material design increases the neutron intensity.

Oral presentation

Current status of JRR-3; After 3.11 Earthquake in Japan

Murayama, Yoji; Arai, Masaji; Maruo, Takeshi

no journal, , 

JRR-3 at Tokai site of JAEA was in its regular maintenance period, when the Great East Japan Earthquake was taken place on 11th March 2011. The reactor building with their solid foundations and the equipment important to safety survived the earthquake without serious damage and no radioactive leakage has been occurred. Recovery work is planned to be completed by the end of this March. At the same time, check and test of the integrity of all components and seismic assessment to show resistance with the 311 earthquake have been carried out. JRR-3 will restart its operation after completing above mentioned procedures.

Oral presentation

Current status of JRR-3; After 3.11 Earthquake in Japan

Arai, Masaji; Murayama, Yoji; Wada, Shigeru

no journal, , 

JRR-3 at Tokai site of JAEA was in its regular maintenance period, when the Great East Japan Earthquake was taken place on 11th March 2011. The reactor building with their solid foundations and the equipment important to safety survived the earthquake without serious damage and no radioactive leakage has been occurred. Recovery work is planned to be completed by the end of this March. At the same time, check and test of the integrity of all components and seismic assessment to show resistance with the 3.11 earthquake have been carried out. JRR-3 will restart its operation after completing above mentioned procedures.

Oral presentation

Upgrading of the neutron transport efficiency of C3 cold neutron guides at JRR-3

Tamura, Itaru; Nagahori, Kazuhisa; Arai, Masaji; Sasajima, Fumio; Wada, Shigeru

no journal, , 

no abstracts in English

Oral presentation

Development of a new silicon holder with a neutron filter for the JRR-3 silicon-doping

Komeda, Masao; Arai, Masaji; Wada, Shigeru; Kimura, Takahiro*; Kawasaki, Kozo*

no journal, , 

no abstracts in English

27 (Records 1-20 displayed on this page)