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1
Confirmation of feasibility of fabrication technology and characterization of high-packing fraction fuel compact for HTGR
Mizuta, Naoki; Ueta, Shohei; Aihara, Jun; Shibata, Taiju
JAEA-Technology 2017-004, 22 Pages, 2017/03
Confirmation of feasibility of fabrication technology and characterization of the high-packing fraction fuel compact of High Temperature Gas Reactor (HTGR) fuel were carried out. Fuel compacts were fabricated with CFP packing fraction targeted at 33 percent by the same manufacturing condition of HTTR fuel compact. SiC-defective fraction, compressive strength and internal CFP distribution of the compact, important parameters to guarantee its integrity, were evaluated. The high-packing fuel compacts showed as same level of SiC-defective fraction as that of HTTR first loading fuel, 8$$times$$10$$^{-5}$$, and larger compressive strength than the HTTR fuel criteria, 4,900N. The feasibility of fabrication technology and the performance for the high-packing fraction fuel compact was confirmed.
2
Neutronic characteristic of HTTR fuel compact with various packing models of coated fuel particle
Hohai, Q.; Honda, Yuki; Goto, Minoru; Takada, Shoji
JAEA-Technology 2016-040, 16 Pages, 2017/03
To study the packing effects of the truncated coated fuel particle on the criticality for the High Temperature engineering Test Reactor (HTTR), four alternative models including the truncated uniform model, the non-truncated uniform model, the truncated random model and the non-truncated random model for the arrangement of CFP in fuel compact were used, and the neutronic and criticality calculation were performed by using Monte Carlo MCNP6 code with ENDF/B-VII.1 cross section library. The results showed that the infinite multiplication factors (k$$_{inf}$$) in the truncated models were lower than those of the non-truncated models regardless of the uniform or random arrangement, and the four factors in the four-factor-formula showed that the difference of k$$_{inf}$$ was mainly attributed to the resonance escape probability. The difference in resonance escape probability is caused by the increase of capture reactions in the resonance region as the influence of spatial-self-shielding-effect. It is because the equivalent kernel diameter of the CFP for the truncated model is smaller than that of the non-truncated model.
3
Operation, test, research and development of the High Temperature Engineering Test Reactor (HTTR); FY2015
Department of HTTR
JAEA-Review 2016-036, 95 Pages, 2017/03
The High Temperature Engineering Test Reactor (HTTR) was attained at the full power operation of 30 MW in December 2001 and achieved the 950 degrees of coolant outlet temperature at outside of the reactor pressure vessel in June 2004. This report summarizes activities and results of HTTR operation, maintenance, and several Research and developments, which were carried out in the fiscal year 2015.
4
Development of fuel temperature calculation code "FTCC" for high temperature gas-cooled reactors
Inaba, Yoshitomo; Isaka, Kazuyoshi; Shibata, Taiju
JAEA-Data/Code 2017-002, 74 Pages, 2017/03
In order to ensure the thermal integrity of fuel in High Temperature Gas-cooled Reactors (HTGRs), it is necessary that the maximum fuel temperature in normal operation is to be lower than a thermal design target. In the core thermal-hydraulic design of block-type HTGRs, the maximum fuel temperature should be evaluated considering data such as core geometry and specifications, power density and neutron fluence distributions, and core coolant flow distribution. The fuel temperature calculation code used in the design stage of the High Temperature engineering Test Reactor (HTTR) presupposes to run on UNIX systems, and its operation and execution procedure are complicated and are not user-friendly. Therefore, a new fuel temperature calculation code, named FTCC, which has a user-friendly system such as a simple and easy operation and execution procedure, was developed. This report describes the calculation objects and models, the basic equations, the strong points (improvement points from the HTTR design code), the code structure, the using method of FTCC, and the result of a validation calculation with FTCC. The calculation result obtained by FTCC provides good agreement with that of the HTTR design code, and then FTCC will be used as one of the design codes for high temperature gas-cooled reactors. In addition, the effect of hot spot factors and fuel cooling forms on reducing the maximum fuel temperature is investigated with FTCC. As a result, it was found that the effect of center hole cooling for hollow fuel compacts and gapless cooling with monolithic type fuel rods on reducing the temperature is very high.
5
Development of fuel temperature calculation code for HTGRs
Inaba, Yoshitomo; Nishihara, Tetsuo
Annals of Nuclear Energy, 101, p.383 - 389, 2017/03
 Percentile:0(Nuclear Science & Technology)
In order to ensure the thermal integrity of fuel in High Temperature Gas-cooled Reactors (HTGRs), it is necessary that the maximum fuel temperature in normal operation is to be lower than a thermal design target. In the core thermal-hydraulic design of block-type HTGRs, the maximum fuel temperature should be evaluated considering data such as thermal power, core geometry, power density and neutron fluence distributions, and core coolant flow distribution. The fuel temperature calculation code used in the design stage of the High Temperature engineering Test Reactor (HTTR) presupposes to run on UNIX systems, and its operation and execution procedure are complicated and are not user-friendly. Therefore, a new fuel temperature calculation code named FTCC which has a user-friendly system such as a simple and easy operation and execution procedure, was developed. This paper describes calculation objects and models, basic equations, improvement points from the HTTR design code in FTCC, and the result of a validation calculation with FTCC. The calculation result obtained by FTCC provides good agreement with that of the HTTR design code, and then FTCC will be used as one of the design codes for HTGRs. In addition, the effect of cooling forms on the maximum fuel temperature is investigated by using FTCC. As a result, it was found that the effect of center hole cooling for hollow fuel compacts and gapless cooling with monolithic type fuel rods on reducing the temperature is very high.
6
Development of transportation container for neutron startup source of High Temperature Engineering Test Reactor (HTTR)
Shimazaki, Yosuke; Sawahata, Hiroaki; Yanagida, Yoshinori; Shinohara, Masanori; Kawamoto, Taiki; Takada, Shoji
JAEA-Technology 2016-038, 36 Pages, 2017/02
The High Temperature Engineering Test Reactor (HTTR) has three neutron startup sources (NSs) in the reactor core, each of which consists of $$^{252}$$Cf with 3.7GBq The NSs are exchanged at the interval of approximately 7 years. The NS holders including NSs are transported from the dealer's hot cell to the reactor facility of HTTR using a transportation container. The loading work of NS holders to the Control Rod guide blocks is subsequently carried out in the fuel handling machine maintenance pit of HTTR. Following technical issues were extracted from the experiences in the past two exchange works of NSs to develop a safety handling procedure; (1) The reduction and prevention of radiation exposure of workers. (2) The exclusion of falling of NS holder. Then, a new transportation container special to the NSs of HTTR was developed to solve the technical issues while keeping the cost as low as that for overhaul of conventional container and satisfying the regulation of A type transportation package.
7
Improvement of neutron startup source handling work by developing new transportation container for High-Temperature engineering Test Reactor (HTTR)
Shimazaki, Yosuke; Sawahata, Hiroaki; Shinohara, Masanori; Yanagida, Yoshinori; Kawamoto, Taiki; Takada, Shoji
Journal of Nuclear Science and Technology, 54(2), p.260 - 266, 2017/02
 Percentile:0(Nuclear Science & Technology)
The High-Temperature engineering Test Reactor (HTTR) has three neutron startup sources (NSs) in the reactor core, each of which consists of $$^{252}$$Cf with 3.7 GBq and is contained in a small capsule, installed in NS holder and subsequently in a control guide block (CR block). The NSs are exchanged at the interval of approximately 7 years. The NS holders are transported from the dealer's hot cell to the reactor facility of HTTR using a transportation container. The loading work of NS holders to the CR blocks is subsequently carried out in the fuel handling machine maintenance pit of HTTR. Technical issues, which are the reduction and prevention of radiation exposure of workers and the exclusion of falling of NS holder, were extracted from the experiences in past two exchange works of NSs to develop a safety handling procedure. Then, a new transportation container special to the NSs of HTTR was developed to solve the technical issues while keeping the cost as low as that for overhaul of conventional container. As the results, the NS handling work using the new transportation container was safely accomplished by developing the new transportation container which can reduce the risks of radiation exposure dose of workers and exclude the falling of NS holder.
8
Shielding calculation by PHITS code during replacement works of startup neutron sources for HTTR operation
Shinohara, Masanori; Ishitsuka, Etsuo; Shimazaki, Yosuke; Sawahata, Hiroaki
JAEA-Technology 2016-033, 65 Pages, 2017/01
To reduce the neutron exposure dose for workers during the replacement works of the startup neutron sources of the High Temperature Engineering Test Reactor, calculations of the exposure dose in case of temporary neutron shielding at the bottom of fuels handling machine were carried out by the PHITS code. As a result, it is clear that the dose equivalent rate due to neutron radiation can be reduced to about an order of magnitude by setting a temporary neutron shielding at the bottom of shielding cask for the fuel handling machine. In the actual replacement works, by setting temporary neutron shielding, it was achieved that the cumulative equivalent dose of the workers was reduced to 0.3 man mSv which is less than half of cumulative equivalent dose for the previous replacement works; 0.7 man mSv.
9
Sustainable and safe energy supply with seawater uranium fueled HTGR and its economy
Fukaya, Yuji; Goto, Minoru
Annals of Nuclear Energy, 99, p.19 - 27, 2017/01
 Percentile:0(Nuclear Science & Technology)
Sustainable and safe energy supply with seawater fueled HTGR have been investigated to sustain the nuclear energy safely by electricity generation with HTGR, the uranium resources must be inexhaustible. The seawater uranium is expected to be alternative resources to conventional resources. It is said that 4.5 billion tons of uranium is dissolved in the seawater, which corresponds to a consumption of approximately 72 thousand years. The uranium dissolved in seawater is in an equilibrium state with the uranium on surface of sea floor, which is approximately a thousand times of the amount, that is 72 million years. It can be recoverable. In other words, the uranium from seawater is almost inexhaustible natural resource. The cost of extracting uranium from seawater with current technology is still expensive compared with that of conventional uranium. However, the economy of nuclear power generation fueled by seawater uranium should be assessed for entire electricity generation cost. In the present study, the economy of electricity generation using uranium from seawater is assessed using a commercial HTGR. Compared with ordinary LWR using conventional uranium, HTGR can realize lower cost of electricity owing to small volume of simple direct gas turbine system compared with water and steam systems of LWR, rationalization by modularizing, and high thermal efficiency, even if fueled by seawater uranium. It is concluded that the HTGR fueled by seawater uranium with the current technology enables the energy sustainability to be maintained for a long term approximately 70 million years with superior inherent safety features and low cost of 7.28 yen/kWh, which is lower than the 8.80 yen/kWh cost of LWR using conventional uranium.
10
Investigation of absorption characteristics for thermal-load fluctuation using HTTR
Tochio, Daisuke; Honda, Yuki; Sato, Hiroyuki; Sekita, Kenji; Homma, Fumitaka; Sawahata, Hiroaki; Takada, Shoji; Nakagawa, Shigeaki
Journal of Nuclear Science and Technology, 54(1), p.13 - 21, 2017/01
 Percentile:0(Nuclear Science & Technology)
GTHTR300C is designed and developed in JAEA. The reactor system is required to continue a stable and safety operation as well as a stable power supply in the case that thermal-load is fluctuated by the occurrence of abnormal event in the heat utilization system. Then, it is necessary to demonstrate that the thermal-load fluctuation should be absorbed by the reactor system so as to continue the stable and safety operation could be continued. The thermal-load fluctuation absorption tests without nuclear heating were planned and conducted in JAEA to clarify the absorption characteristic of thermal-load fluctuation mainly by the reactor and by the IHX. As the result it was revealed that the reactor has the larger absorption capacity of thermal-load fluctuation than expected one, and the IHX can be contributed to the absorption of the thermal-load fluctuation generated in the heat utilization system in the reactor system. It was confirmed from there result that the reactor and the IHX has effective absorption capacity of the thermal-load fluctuation generated in the heat utilization system. Moreover it was confirmed that the safety estimation code based on RELAP5/MOD3 can represents the thermal-load fluctuation absorption behavior conservatively.
11
Proposals of new basic concepts on safety and radioactive waste and of new high temperature gas-cooled reactor based on these basic concepts
Ogawa, Masuro
Nuclear Engineering and Design, 308, p.133 - 141, 2016/11
A new basic concept on safety; Not causing any serious catastrophe by any means and a new basic concept on radioactive waste; Not returning any waste that possibly affects the environment are proposed in the present study, aiming at nuclear power plants which everybody can accept, in consideration of the serious catastrophe that happened at Fukushima in 2011. In the present study, physical phenomena are used to continue confining, rather than confine. To continue confining is meant to apply natural correction to fulfill inherent safety function. Fission products must be detoxified to realize the new basic concept on radioactive waste, aiming at the final processing and disposal of radioactive wastes as same as that in the other wastes such as PCB. The New HTGR is proposed based on the new basic concepts. It is indicated that the New HTGR can response to social requirements for safety and environmental conservability against radioactive wastes, industrial requirements for economy, uranium resource sustainability and so on, and national requirements for non-proliferation and environmental protection against carbon dioxide.
12
Nuclear thermal design of high temperature gas-cooled reactor with SiC/C mixed matrix fuel compacts
Aihara, Jun; Goto, Minoru; Inaba, Yoshitomo; Ueta, Shohei; Sumita, Junya; Tachibana, Yukio
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (USB Flash Drive), p.814 - 822, 2016/11
Japan Atomic Energy Agency (JAEA) has started R&D for apply SiC/C mixed matrix to fuel element of high temperature gas-cooled reactors (HTGRs) to improve oxidation resistance of fuel. Nuclear thermal design of HTGR with SiC/C mixed matrix fuel compacts was carried out as a part of above R&Ds. Nuclear thermal design was carried out based on a small sized HTGR for developing countries, HTR50S. Maximum enrichment of uranium is set to be 10 wt%, because coated fuel particles with 10 wt% uranium have been fabricated in Japan. Numbers of kinds of enrichment and burnable poisons (BPs) were set to be same as those of original HTR50S (3 and 2, respectively). We succeeded in nuclear thermal design of a small sized HTGR which performance was equivalent to original HTR50S, with SiC/C mixed matrix fuel compacts. Based on nuclear thermal design, intactness of coated fuel particles was evaluated to be kept on internal pressure during normal operation.
13
HTTR-GT/H$$_{2}$$ test plant; System performance evaluation for HTTR gas turbine cogeneration plant
Sato, Hiroyuki; Nomoto, Yasunobu; Horii, Shoichi; Sumita, Junya; Yan, X.; Ohashi, Hirofumi
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (USB Flash Drive), p.759 - 766, 2016/11
This paper presents the system performance evaluation for HTTR gas turbine cogeneration test plant (HTTR-GT/H$$_{2}$$ plant) so as to confirm that the design meets the requirements with respect to the demonstration test objective. Start-up and shut down operation sequences as well as operability of load following operation were investigated. In addition, system dynamic and control analyses for the test plant in the events of loss of generator load and upset of H$$_{2}$$ plant were performed. The simulation results presented in the paper show that the test plant is suitable for the test bed to validate control schemes against postulated transients in the commercial Gas Turbine High Temperature Reactor Cogeneration (GTHTR300C). The results also lead us to the conclusion that HTTR-GT/H$$_{2}$$ plant can be used to test operational procedure unique to HTGR direct-cycle gas turbine cogeneration.
14
Sensitivity analysis of xenon reactivity temperature dependency for HTTR LOFC test by using RELAP5-3D code
Honda, Yuki; Fukaya, Yuji; Nakagawa, Shigeaki; Baker, R. I.*; Sato, Hiroyuki
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (USB Flash Drive), p.704 - 713, 2016/11
A high-temperature gas-cooled reactor (HTGR) has superior safety characteristics. A loss of forced cooling (LOFC) test using a high-temperature engineering test reactor (HTTR) has been carried out to verify the inherent safety of an HTGR when forced cooling is diminished without reactor scram. In the test, an all-gas circulator was tripped with an initial reactor power of 9 MW and re-criticality was shown. This study focuses on developing a point kinetics method with RELAP5-3D code for an LOFC accident. There is a large temperature difference between the inlet and outlet of the core in an HTGR, and the temperature fluctuation range has been large in several accidents. We analyze the temperature dependency of xenon-135 reactivity and show that the temperature dependency of xenon-135 microscopic absorption cross-section affected the re-criticality time of the LOFC test.
15
IS process hydrogen production test for components and system made of industrial structural material, 2; H$$_{2}$$SO$$_{4}$$ decomposition, HI distillation, and HI decomposition section
Noguchi, Hiroki; Takegami, Hiroaki; Kamiji, Yu; Tanaka, Nobuyuki; Iwatsuki, Jin; Kasahara, Seiji; Kubo, Shinji
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (USB Flash Drive), p.1029 - 1038, 2016/11
JAEA has been conducting R&D on the IS process for nuclear-powered hydrogen production. We have constructed a 100 NL/h-H$$_2$$-scale test apparatus made of industrial materials. At first, we investigated performance of components in this apparatus. In this paper, the test results of H$$_2$$SO$$_4$$ decomposition, HI distillation, and HI decomposition were shown. In the H$$_2$$SO$$_4$$ section, O$$_2$$ production rate is proportional to H$$_2$$SO$$_4$$ feed rate and SO$$_3$$ decomposition ratio was estimated about 80%. In HI distillation section, we confirmed to acquire a concentrated HI solution over azeotropic HI composition in the condenser. In HI decomposition section, H$$_2$$ could be produced stably by HI decomposer and decomposition ratio was about 18%. The H$$_2$$SO$$_4$$ decomposer, the HI distillation column, and the HI decomposer were workable. Based on the results added to that shown in Series I, we conducted a trial continuous operation and succeeded it for 8 hours.
16
IS process hydrogen production test for components and system made of industrial structural material, 1; Bunsen and HI concentration section
Tanaka, Nobuyuki; Takegami, Hiroaki; Noguchi, Hiroki; Kamiji, Yu; Iwatsuki, Jin; Aita, Hideki; Kasahara, Seiji; Kubo, Shinji
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (USB Flash Drive), p.1022 - 1028, 2016/11
Japan Atomic Energy Agency (JAEA) has manufactured 100 NL/h-H$$_2$$-scale hydrogen test apparatus. In advance to conduct the continuous operation, we investigated performance of the components in each section of the IS process. In this paper, the results of test of Bunsen and HI concentration sections was shown. In Bunsen reaction, section, we confirmed that outlet gas flow rate included no SO$$_{2}$$ gas, indicating that all the feed SO$$_{2}$$ gas was absorbed to the solution in the Bunsen reactor for the Bunsen reaction. On the basis of these results, we evaluated that Bunsen reactor was workable. In HI concentration section, HI concentration was conducted by EED stack. As a result, it can concentrate HI in HIx solution as theoretically predicted on the basis of the previous paper. Based on the results added to that shown in Series II, we have conducted a trial continuous operation and succeeded it for 8 hours.
17
Development of safety requirements for HTGRs design
Ohashi, Hirofumi; Sato, Hiroyuki; Nakagawa, Shigeaki; Tokuhara, Kazumi; Nishihara, Tetsuo; Kunitomi, Kazuhiko
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (USB Flash Drive), p.330 - 340, 2016/11
The safety requirements for the design of HTGRs has been developed by the research committee established in the Atomic Energy Society of Japan so as to incorporate the HTGR safety features demonstrated by HTTR, lessons learned from the accident of Fukushima Daiichi Nuclear Power Station and requirements for the coupling of the hydrogen production plants with nuclear plant. The safety design approach was determined to establish a high level of safety design standards by utilizing inherent safety features of HTGRs. This paper describes the process to develop the HTGR specific safety requirements and overview of the proposed HTGR specific safety requirements.
18
The IAEA coordinated research project on modular HTGR safety design; Status and outlook
Reitsma, F.*; Kunitomi, Kazuhiko; Ohashi, Hirofumi
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (USB Flash Drive), p.341 - 352, 2016/11
The IAEA Coordinated Research Project (CRP) on Modular High Temperature Gas-cooled Reactor (HTGR) Safety Design started in December 2014 and is now in its second year of implementation. The project investigates and makes proposals on safety design criteria by not only considering the existing water cooled reactors safety requirements for nuclear power plant design but also making use of past and current experience of HTGR licensing in the IAEA member states including Japan. The detailed project content and a description of modular HTGRs and its safety features are given. This informs the comments made on the applicability of the existing requirements and the examples of newly proposed HTGR specific safety requirements under development.
19
Development of a core coolant flow distribution calculation code for HTGRs
Inaba, Yoshitomo; Honda, Yuki; Nishihara, Tetsuo
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (USB Flash Drive), p.985 - 990, 2016/11
In order to ensure the thermal integrity of fuel in high temperature gas-cooled reactors (HTGRs), it is necessary that the maximum fuel temperature in the normal operation is to be lower than the thermal design target. In the core thermal-hydraulic design of block-type HTGRs, the maximum fuel temperature should be evaluated considering data such as thermal power, core geometry, power and neutron fluence distributions, and core coolant flow distribution. The core coolant flow distribution calculation code used in the design stage of High Temperature engineering Test Reactor (HTTR) presupposes to run on UNIX systems, and its operation and execution procedure are complicated and not user-friendly. Therefore, a new core coolant flow distribution calculation code with a user-friendly system such as simple and easy operations and execution procedures has been developed. In this paper, the outline of the new code is described and the simulation result of an out-of-pile test with one fuel column is shown as the first step of the code validation. The simulation results provide good agreement with the test one.
20
Irradiation test about oxidation-resistant graphite in WWR-K research reactor
Shibata, Taiju; Sumita, Junya; Sakaba, Nariaki; Osaki, Takashi*; Kato, Hideki*; Izawa, Shoichi*; Muto, Takenori*; Gizatulin, S.*; Shaimerdenov, A.*; Dyussambayev, D.*; et al.
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (USB Flash Drive), p.567 - 571, 2016/11
Graphite are used for the in-core components of HTGR, and it is desirable to enhance oxidation resistance to keep much safety margin. SiC coating is the candidate method for this purpose. JAEA and four Japanese graphite companies are studying to develop oxidation-resistant graphite. Neutron irradiation test was carried out by WWR-K reactor of INP of Kazakhstan through ISTC partner project. The total irradiation cycles of WWR-K operation was 10 cycles by 200 days. Irradiation temperature about 1473 K would be attained. The maximum fast neutron fluence (E $$>$$0.18 MeV) for the capsule irradiated at a central irradiation hole was preliminary calculated as 1.2$$times$$10$$^{25}$$/m$$^{-2}$$, and for the capsule at a peripheral irradiation hole as 4.2$$times$$10$$^{24}$$/m$$^{-2}$$. Dimension and weight of the irradiated specimens were measured, and outer surface of the specimens were observed by optical microscope. For the irradiated oxidation resistant graphite, out-of-pile oxidation test will be carried out at an experimental laboratory.