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Journal Articles

Nuclear and thermal feasibility of lithium-loaded high temperature gas-cooled reactor for tritium production for fusion reactors

Goto, Minoru; Okumura, Keisuke; Nakagawa, Shigeaki; Inaba, Yoshitomo; Matsuura, Hideaki*; Nakaya, Hiroyuki*; Katayama, Kazunari*

Fusion Engineering and Design, 136(Part A), p.357 - 361, 2018/11

 Times Cited Count:3 Percentile:53.84(Nuclear Science & Technology)

A High Temperature Gas-cooled Reactor (HTGR) is proposed as a tritium production device, which has the potential to produce a large amount of tritium using $$^{6}$$Li(n,$$alpha$$)T reaction. In the HTGR design, generally, boron is loaded into the core as a burnable poison to suppress excess reactivity. In this study, lithium is loaded into the HTGR core instead of boron and is used as a burnable poison aiming to produce thermal energy and tritium simultaneously. The nuclear characteristics and the fuel temperature were calculated to confirm the feasibility of the lithium-loaded HTGR. It was shown that the calculation results satisfied the design requirements and hence the feasibility was confirmed for the lithium-loaded HTGR, which produce thermal energy and tritium.

Journal Articles

Mechanical characteristics of rock segment for reducing amount of cement use and stability of drift tunnel

Tada, Hiroyuki*; Kumasaka, Hiroo*; Saito, Akira*; Nakaya, Atsushi*; Ishii, Takashi*; Fujita, Tomoo; Sugita, Yutaka; Nakama, Shigeo; Sanada, Masanori*

Doboku Gakkai Rombunshu, F2 (Chika Kukan Kenkyu) (Internet), 73(1), p.11 - 28, 2017/03

This study examined the mechanical characteristics of rock segments and backfill materials and analyzed the stability of the drift that is supported by the rock segments and gravel backfill. The results confirmed the technical aspects of the formation of the rock segments and the effectiveness of the planned efforts to further reduce the amount of cement used.

Journal Articles

A Study on transmutation of LLFPs using various types of HTGRs

Kora, Kazuki*; Nakaya, Hiroyuki*; Matsuura, Hideaki*; Goto, Minoru; Nakagawa, Shigeaki; Shimakawa, Satoshi*

Nuclear Engineering and Design, 300, p.330 - 338, 2016/04

 Times Cited Count:6 Percentile:49.96(Nuclear Science & Technology)

In order to investigate the potential of high temperature gas-cooled reactors (HTGRs) for transmutation of long-lived fission products (LLFPs), numerical simulation of four types of HTGRs were carried out. In addition to the gas-turbine high temperature reactor system "GTHTR300", a small modular HTGR plant "HTR50S" and two types of plutonium burner HTGRs "Clean Burn with MA" and "Clean Burn without MA" were considered. The simulation results show that an early realization of LLFP transmutation using a compact HTGR may be possible since the HTR50S can transmute fair amount of LLFPs for its thermal output. The Clean Burn with MA can transmute a limited amount of LLFPs. However, an efficient LLFP transmutation using the Clean Burn without MA seems to be convincing as it is able to achieve very high burn-ups and produce LLFP transmutation more than GTHTR300. Based on these results, we propose utilization of variety of HTGRs for LLFP transmutation and storage.

Journal Articles

Study on operation scenario of tritium production for a fusion reactor using a high temperature gas-cooled reactor

Kawamoto, Yasuko*; Nakaya, Hiroyuki*; Matsuura, Hideaki*; Katayama, Kazunari*; Goto, Minoru; Nakagawa, Shigeaki

Fusion Science and Technology, 68(2), p.397 - 401, 2015/09

 Times Cited Count:1 Percentile:9.82(Nuclear Science & Technology)

To start up a fusion reactor, it is necessary to provide a sufficient amount of tritium from an external device. Herein, methods for supplying a fusion reactor with tritium are discussed. Use of a high temperature gas cooled reactor (HTGR) as a tritium production device has been proposed. So far, the analyses have been focused only on the operation in which fuel is periodically exchanged (batch) using the block type HTGR. In the pebble bed type HTGR, it is possible to design an operation that has no time loss for refueling. The pebble bed type HTGR (PBMR) and the block type HTGR (GTHTR300) are assumed as the calculation and comparison targets. Simulation is made using the continuous-energy Monte Carlo transport code MVPBURN. It is shown that the continuous operation using the pebble bed type HTGR has almost the same tritium productivity compared with the batch operation using the block type HGTR. The issues for pebble bed type HTGR as a tritium production device are discussed.

Journal Articles

Application of the high-temperature gas-cooled reactor to produce tritium for fusion reactors

Nakaya, Hiroyuki*; Matsuura, Hideaki*; Katayama, Kazunari*; Goto, Minoru; Nakagawa, Shigeaki

Proceedings of 2015 International Congress on Advances in Nuclear Power Plants (ICAPP 2015) (CD-ROM), p.398 - 402, 2015/05

The performance of tritium production for fusion reactor using High-Temperature Gas-cooled Reactor (HTGR) is studied. An influence of $$^{6}$$Li concentration on tritium production performance using HTGR is estimated. Li compound is loaded in the reactor core using Li rod consisting cylindrical Li compound in cladding tube. A Gas Turbine High-Temperature Reactor of 300 MWe nominal capacity (GTHTR300) with 600 MW thermal output power is assumed as HTGR. An amount of tritium production is estimated by burn-up calculations using the continuous-energy Monte Carlo transport code MVP-BURN. The amount of tritium outflow is estimated from equilibrium solution for the tritium diffusion equation in the cladding tube. Even if 6Li is enriched, the GTHTR300 can produce 500 g of tritium over 180-day operation without increasing the amount of required $$^{6}$$Li. The amount of tritium outflow is decreased by 20-50%.

Journal Articles

Study on transmutation and storage of LLFP using a high-temperature gas-cooled reactor

Kora, Kazuki*; Nakaya, Hiroyuki*; Kubo, Kotaro*; Matsuura, Hideaki*; Shimakawa, Satoshi; Goto, Minoru; Nakagawa, Shigeaki

Proceedings of International Conference on the Physics of Reactors; The Role of Reactor Physics toward a Sustainable Future (PHYSOR 2014) (CD-ROM), 12 Pages, 2014/09

In this study, the capability of HTGR as LLFP transmuter was evaluated in terms of neutron economy. Considering gas turbine high-temperature reactor with 300 MWe nominal capacity (GTHTR300) as HTGR, transmutations of four types of LLFP nuclide were estimated using Monte Carlo transport code MVP and ORIGEN. In addition, burn-up simulations for whole-core region were carried out using MVP-BURN. It was numerically shown that the neutron fluxes change significantly depending on the arrangement of LLFP in the core. When 15 t of LLFP is placed in an ideal manner, the GTHTR300 can sustain sufficient reactivity for one year while transmuting up to 30 kg per year. Additionally, there are more space available for storing larger amount of LLFP without affecting the reactivity. These results suggest that there is a possibility of using GTHTR300 as both LLFP storage and transmuter.

Journal Articles

Development of rock segment for reduction of amount of cement use

Tada, Hiroyuki*; Kumasaka, Hiroo*; Saito, Akira*; Nakaya, Atsushi*; Ishii, Takashi*; Sanada, Masanori; Noguchi, Akira*; Kishi, Hirokazu*; Nakama, Shigeo; Fujita, Tomoo

Dai-13-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.133 - 138, 2013/01

The authors have been developing methods for constructing tunnels using the minimum quantities of cement-type support materials in high-level radioactive waste disposal facilities and advancing research and development about the technical formation of rock segment using low alkaline mortar. In this study, the mechanical characteristic values concerning the rock segment and backfill materials were examined. The stability analysis of tunnel supported by the rock segment and backfilling with gravel were performed. Technical formation and effectiveness of the alternative supports planned for further reduction in cement influence was confirmed from a study result above-mentioned.

JAEA Reports

A Study on the technology for reducing cement-type materials used for tunnel supports at high-level radioactive waste disposal sites (Joint research)

Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Kabayashi, Yasushi*; Nakama, Shigeo; Fujita, Tomoo; Naito, Morimasa; Tada, Hiroyuki*; Kumasaka, Hiroo*; Goke, Mitsuo*; et al.

JAEA-Research 2010-057, 101 Pages, 2011/03

JAEA-Research-2010-057.pdf:7.47MB

Cement-type materials that are used for supports or grouting at high-level radioactive waste disposal facilities leach into the groundwater and create a highly alkaline environment. Of concern in highly alkaline environments are the alteration of bentonite used as buffers or backfill materials, and of surrounding rock mass, and the increased uncertainty regarding the provision of performance of the disposal system over a long period of time. In this study, to reduce the quantity of cement-type materials that cause highly alkaline environments, technical feasibility of the support structure including the materials which considered the long-term performance of the HLW disposal system are discussed by using knowledge and technology accumulated in JAEA and Shimizu Construction. Moreover, based on the results, the problems remained in the application to the future HLW disposal institution are summarized.

Oral presentation

Development of construction method for a drift minimizing use of cementious material, 7; Experimental study on the rock mortar composite material based on low alkaline cement

Saito, Akira*; Nakaya, Atsushi*; Tada, Hiroyuki*; Kumasaka, Hiroo*; Kobayashi, Yasushi

no journal, , 

no abstracts in English

Oral presentation

Development of construction methods of a drift to be reduction of amount of cement use, 8; The Bending test of the rock segment using low alkaline mortar

Saito, Akira*; Goke, Mitsuo*; Nakaya, Atsushi*; Tada, Hiroyuki*; Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Nakama, Shigeo

no journal, , 

We are supposing a low cement use tunner support made for granite rock block connecting low alkaline cement applying to HLW repositories. Because of the bending moment of the segment by dead load and the variance of the earth pressure, We made a model segment bending experiment to get a mechanical properties. The maximum load of the positive bending moment is around 210kN, which is around twice of the dead load of 117kN. The other hand, the maximum load in the negative bending moment is around 44kN, as same as the dead load. As the result of observating the cracks of the model segment, We found three or four cracks along the surface of the boundary of the rock block and mortar in the positive bending experiment. The other hand, we found only one crack at the center avoiding rock block in the negative bending experiment. Next, we will improve the construction method, prevention of the crack in the segment and the exfoliation of mortar and the steel panel.

Oral presentation

Development of construction methods of a drift to be reduction of amount of cement use, 9; Test of a deformation of macadam and stability of drift tunnel

Kumasaka, Hiroo*; Saito, Akira*; Nakaya, Atsushi*; Tada, Hiroyuki*; Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Nakama, Shigeo

no journal, , 

We are proposing to use the rock segment reducing the amount of the cementutious materials. In this report, we are getting young's modulus and poisson's ratio from the deformation experiment of the macadam mass, and performed a stability analysis of the gallery filled with macadam between the hostrock and the rock segment. We performed a alternating bearing test with high confirming pressure, and we estimated the Young's modulus and the poisson's ratio of the mass macadam from the result of the bearing test. After that, we performed the stability analysis of the galleries in the condition of the JAEA second report with the rock segment and the macadam. We found that the strain at the surface of the host rock is smaller than that of conventional one, and the stability of the host rock is remained, and the compressive stress in the rock segment is the half of the compressive strength of it. We considered that the rock segment support system is stable enough for the supporting system.

Oral presentation

Study for tritium production for fusion reactors by high temperature gas-cooled reactors

Yasumoto, Takashi*; Matsuura, Hideaki*; Shimakawa, Satoshi; Nakao, Yasuyuki*; Kochi, Shohei*; Nakaya, Hiroyuki*; Goto, Minoru; Nakagawa, Shigeaki

no journal, , 

no abstracts in English

Oral presentation

Development of construction methods of a drift to be reduction of amount of cement use, 10; Study on bending properties of the rock segment using low alkaline mortar

Tada, Hiroyuki*; Saito, Akira*; Nakaya, Atsushi*; Kumasaka, Hiroo*; Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Nakama, Shigeo

no journal, , 

Bending test of the segmental rings consist of staggered pieces of rocks bonded by low-pH mortar is conducted in order to identify the mechanical properties of rock segmental rings comparing with parallel arrangement. As a result, it was found that the maximum load was reached at 130 to 210 kN in the positive bending tests for staggered rock blocks, lower than 210 to 270 kN for rock blocks arranged in parallel. In the negative bending tests, on the other hand, the maximum load was reached at 30 to 40 kN, lower than a maximum load of 40 kN for the rock blocks arranged in parallel. The results thus varied. Cracks occurred along the interface between the rock block and mortar in the specimen for the blocks arranged in parallel. For the staggered rock blocks, cracks penetrated through the mortar and the rock block near the point of loading in the specimen. Thus, it was confirmed that cracking occurred in different manners.

Oral presentation

Study for tritium production for fusion reactors by high temperature gas-cooled reactors

Yasumoto, Takashi*; Matsuura, Hideaki*; Shimakawa, Satoshi; Nakao, Yasuyuki*; Kochi, Shohei*; Nakaya, Hiroyuki*; Goto, Minoru; Nakagawa, Shigeaki; Nishikawa, Masabumi*

no journal, , 

no abstracts in English

Oral presentation

Study to transmute long life fission products into short-lived nuclides

Kochi, Shohei*; Nakaya, Hiroyuki*; Shimakawa, Satoshi; Matsuura, Hideaki*; Yasumoto, Takashi*; Nakao, Yasuyuki*; Goto, Minoru; Nakagawa, Shigeaki

no journal, , 

no abstracts in English

Oral presentation

Study for tritium production for fusion reactor by high-temperature gas-cooled reactor

Matsuura, Hideaki*; Yasumoto, Takashi*; Shimakawa, Satoshi; Kochi, Shohei*; Nakaya, Hiroyuki*; Nakao, Yasuyuki*; Goto, Minoru; Nakagawa, Shigeaki; Nishikawa, Masabumi*

no journal, , 

no abstracts in English

Oral presentation

Performance of high-temperature gas-cooled reactor as a tritium production device for fusion reactors

Matsuura, Hideaki*; Kochi, Shohei*; Nakaya, Hiroyuki*; Yasumoto, Takashi*; Nakao, Yasuyuki*; Shimakawa, Satoshi; Goto, Minoru; Nakagawa, Shigeaki; Nishikawa, Masabumi*

no journal, , 

The performance of a high-temperature gas-cooled reactor as a tritium production device for fusion reactors was examined by performing a core burn-up calculation with the continuous-energy Monte Carlo code MVP-BURN. It was shown that the high-temperature gas cooled reactor can contribute to the tritium production for fusion reactors.

Oral presentation

Use of Li control rod and performance of tritium production in high-temperature gas-cooled reactors

Kochi, Shohei*; Matsuura, Hideaki*; Nakaya, Hiroyuki*; Nakao, Yasuyuki*; Shimakawa, Satoshi; Goto, Minoru; Nakagawa, Shigeaki; Nishikawa, Masabumi*

no journal, , 

Changes in a control rod value and a production amount of tritium with burnup were examined with a continuous energy Monte Carlo code MVP-BURN for a high temperature gas cooled reactor in which B$$_{4}$$C control rods were replaced with Li control rods. It was shown that the amount of tritium production was increased about 20% from the previous study and the excess reactivity was properly controlled by installing the Li control rods into the outer region of the core.

Oral presentation

Study of transmutation treatment of long-lived fission products with high temperature gas cooled reactor; Characteristics

Shimakawa, Satoshi; Goto, Minoru; Nakagawa, Shigeaki; Nakaya, Hiroyuki*; Matsuura, Hideaki*; Nakao, Yasuyuki*

no journal, , 

In order to decrease of nuclear waste, the nuclear transmutation method with HTGRs (High Temperature Gas-cooled Reactor) by which a large amount of LLFP (Long Lived Fission Product) can be transmuted is proposed. This paper describes the characteristics of the nuclear transmutation, which are the relations between transmutation efficiency and the amount of loaded LLFP into the core or the characteristics of the irradiation target, are reported.

Oral presentation

Study of tritium production with high temperature gas cooled reactor, 2; Engineering investigation

Goto, Minoru; Nakagawa, Shigeaki; Shimakawa, Satoshi; Matsuura, Hideaki*; Nakao, Yasuyuki*; Nishikawa, Masabumi*; Nakaya, Hiroyuki*

no journal, , 

A High Temperature Gas-cooled Reactor (HTGR) with lithium particle, which can produce a large amount of tritium without the change of the original reactor design, is proposed as a tritium production device for an initial fusion reactor. However, the tritium production using High Temperature Engineering Test Reactor (HTGR) is not carried out so far and the investigation of the problem about its system is not carried out so far, too. Therefore we extracted a problem from an engineering viewpoint and investigated the feasibility. The problems are expected to be solved by using the HTTR technologies, which are manufacturing the coated fuel particle and handling of the fuel, and the system is feasible from an engineering viewpoint.

28 (Records 1-20 displayed on this page)