Nishihara, Tetsuo; Shibata, Taiju; Inaba, Yoshitomo
Hozengaku, 18(1), p.30 - 34, 2019/04
We explain the current status of High Temperature Gas-cooled Reactor (HTGR) development in the world and international cooperation between Japan Atomic Energy Agency (JAEA) and these countries. We introduce the concept of Japanese HTGR technology deployment by using international cooperation.
Fukaya, Yuji; Goto, Minoru; Ohashi, Hirofumi; Yan, X.; Nishihara, Tetsuo; Tsubata, Yasuhiro; Matsumura, Tatsuro
Journal of Nuclear Science and Technology, 55(11), p.1275 - 1290, 2018/11
To reduce environmental burden and thread of nuclear proliferation, multi-recycling fuel cycle with High Temperature Gas-cooled Reactor (HTGR) has been investigated. Those problems are solved by incinerating TRans Uranium (TRU) nuclides, which is composed of plutonium and Minor Actinoide (MA), and there is concept to realize TRU incineration by multi-recycling with Fast Breeder Reactor (FBR). In this study, multi-recycling is realized even with thermal reactor by feeding fissile uranium from outside of the fuel cycle instead of breeding fissile nuclide. In this fuel cycle, recovered uranium by reprocessing and natural uranium are enriched and mixed with recovered TRU by reprocessing and partitioning to fabricate fresh fuels. The fuel cycle was designed for a Gas Turbine High Temperature Reactor (GTHTR300), whose thermal power is 600 MW, including conceptual design of uranium enrichment facility. Reprocessing is assumed as existing Plutonium Uranium Redox EXtraction (PUREX) with four-group partitioning technology. As a result, it was found that the TRU nuclides excluding neptunium can be recycled by the proposed cycle. The duration of potential toxicity decaying to natural uranium level can be reduced to approximately 300 years, and the footprint of repository for High Level Waste (HLW) can be reduced by 99.7% compared with GTHTR300 using existing reprocessing and disposal technology. Suppress plutonium is not generated from this cycle. Moreover, incineration of TRU from Light Water Reactor (LWR) cycle can be performed in this cycle.
Nishihara, Tetsuo; Yan, X.; Tachibana, Yukio; Shibata, Taiju; Ohashi, Hirofumi; Kubo, Shinji; Inaba, Yoshitomo; Nakagawa, Shigeaki; Goto, Minoru; Ueta, Shohei; et al.
JAEA-Technology 2018-004, 182 Pages, 2018/07
Research and development on High Temperature Gas-cooled Reactor (HTGR) in Japan started since late 1960s. Japan Atomic Energy Agency (JAEA) in cooperation with Japanese industries has researched and developed system design, fuel, graphite, metallic material, reactor engineering, high temperature components, high temperature irradiation and post irradiation test of fuel and graphite, high temperature heat application and so on. Construction of the first Japanese HTGR, High Temperature engineering Test Reactor (HTTR), started in 1990. HTTR achieved first criticality in 1998. After that, various test operations have been carried out to establish the Japanese HTGR technologies and to verify the inherent safety features of HTGR. This report presents several system design of HTGR, the world-highest-level Japanese HTGR technologies, JAEA's knowledge obtained from construction, operation and management of HTTR and heat application technologies for HTGR.
Fukaya, Yuji; Kasahara, Seiji; Mizuta, Naoki; Inaba, Yoshitomo; Shibata, Taiju; Nishihara, Tetsuo
JAEA-Research 2018-004, 38 Pages, 2018/06
The demand of HTGR to investigate its introduction scenario and heat balance of HTGR have been researched. First, previous studies of HTGR demand were researched. Next, heat balance of GTHTR300, a commercial scale HTGR design, and its characteristics were researched. By using this information, installation number of HTGR to suit for demand in Japan are evaluated. In addition, heat balance evaluation code was developed in this study.
Tatematsu, Kenji; Nishihara, Tetsuo
JAEA-Evaluation 2018-001, 71 Pages, 2018/06
Executive Director of Sector of Nuclear Science Research in Japan Atomic Energy Agency consulted with the "Evaluation Committee of Research Activities for High Temperature Gas-cooled Reactor and Related Hydrogen Production Technology" (hereinafter referred to as "Evaluation Committee"), which consists of specialists in the fields of the evaluation subjects of high temperature gas-cooled reactor and related heat application technology, about the relevance of the management and research activities of the HTGR Hydrogen and Heat Application Research Center in FY2017.Research activity for FY2017, The Evaluation Committee concluded with a score of S for "Conformity confirmation conformity to HTTR's new regulatory standards", "Cooperation with industry" and "Promotion of international cooperation". Therefore, the Evaluation Committee concluded with a score of A for the overall activity by evaluating that more results than originally required were acquired. Also, regarding the research plan for FY2018, it was judged appropriate. This report summarizes the members of the Evaluation Committee, outlines the method, the review process for procedure of the assessment and that result.
Fukaya, Yuji; Goto, Minoru; Ohashi, Hirofumi; Nishihara, Tetsuo; Tsubata, Yasuhiro; Matsumura, Tatsuro
Annals of Nuclear Energy, 116, p.224 - 234, 2018/06
Optimization of disposal method and scenario to reduce volume of High Level Waste (HLW) and the footprint in a geological repository for High Temperature Gas-cooled Reactor (HTGR) has been performed. It was found that HTGR has great advantages to reducing HLW volume and its footprint, which are high burn-up, high thermal efficiency and pin-in-block type fuel, compared with those of LWR and has potential to reduce those more in the previous study. In this study, the scenario is optimized, and the geological repository layout is designed with the horizontal emplacement based on the KBS-3H concept instead of the vertical emplacement based on KBS-3V concept employed in the previous study. As a result, for direct disposal, the repository footprint can be reduced by 20 % by employing the horizontal without change of the scenario. By extending 40 years for cooling time before disposal, the footprint can be reduced by 50 %. For disposal with reprocessing, the number of canister generation can be reduced by 20 % by extending cooling time of 1.5 years between the discharge and reprocessing. The footprint per electricity generation can be reduced by 80 % by extending 40 years before disposal. Moreover, by employing four-group partitioning technology without transmutation, the footprint can be reduced by 90 % with cooling time of 150 years.
Kunitomi, Kazuhiko; Nishihara, Tetsuo; Yan, X.; Tachibana, Yukio; Shibata, Taiju
Nippon Genshiryoku Gakkai-Shi, 60(4), p.236 - 240, 2018/04
High temperature gas-cooled reactor (HTGR) is a graphite-moderated and helium-gas-cooled thermal-neutron reactor that has excellent safety features and can produce high temperature heat of 950C. It is expected to use for various heat applications as well as for electricity generation to reduce carbon dioxide emission. Japan Atomic Energy Agency (JAEA) has been promoted research and development to demonstrate the HTGR safety features using High temperature engineering test reactor (HTTR) and it's heat application. JAEA are also conducting the action to international deployment of Japanese HTGR technologies in cooperation with industries-government-academia. This paper reports status of the research and development of HTGR and domestic and international collaborations.
Fukaya, Yuji; Goto, Minoru; Nishihara, Tetsuo
Nuclear Engineering and Design, 326, p.108 - 113, 2018/01
Burn-up characteristics and criticality of impurity contained into graphite structure for commercial scale prismatic High Temperature Gas-cooled Reactor (HTGR) have been investigated. For HTGR, of which the core is filled graphite structure, the impurity contained into the graphite has unignorable poison effect for criticality. Then, GTHTR300, commercial scale HTGR, employed high grade graphite material named IG-110 to take into account the criticality effect for the reflector blocks next to fuel blocks. The fuel blocks, which should also employ IG-110, employ lower grade graphite material named IG-11 from the economic perspective. In this study, the necessity of high grade graphite material for commercial scale HTGR is reconsidered by evaluating the burn-up characteristics and criticality of the impurity. The poison effect of the impurity, which is used to be expressed by a boron equivalent, reduces exponentially like burn-up of B, and saturate at a level of 1 % of the initial value of boron equivalent. On the other hand, the criticality effect of the boron equivalent of 0.03 ppm, which corresponds to a level of 1 % of IG-11 shows ignorable values lower than 0.01 %k/kk' for both of fuel blocks and reflector blocks. The impurity can be represented by natural boron without problem. Therefore, the poison effect of the impurity is evaluated with whole core burn-up calculations. As a result, it is concluded that the impurity is not problematic from the viewpoint of criticality for commercial scale HTGR because it is burned clearly until End of Cycle (EOC) even with the low grade graphite material of IG-11. According to this result, more economic electricity generation with HTGR is expected by abolishing the utilization of IG-110.
Tatematsu, Kenji; Nishihara, Tetsuo
JAEA-Evaluation 2017-001, 107 Pages, 2017/09
President of Japan Atomic Energy Agency consulted with the "Evaluation Committee of Research Activities for High Temperature Gas-cooled Reactor and Related Hydrogen Production Technology" (hereinafter referred to as "Evaluation Committee"), which consists of specialists in the fields of the evaluation subjects of high temperature gas-cooled reactor and related heat application technology, about the relevance of the management and research activities of the HTGR Hydrogen and Heat Application Research Center during the period from April 2015 to March 2017. The assessment of the Evaluation Committee concluded with a score of B for the confirmation of adjustability to the new regulation standard for restarting HTTR and for the development of hydrogen production technology, a score of A for the design of HTTR-GT/H test plant completing all equipment design specification and for the development exceeding the original scope of an oxidation resistant fuel element containing SiC. The Evaluation Committee concluded with a score of A for the overall activity. In addition, the Evaluation Committee recommended that the judgement to move to the construction phase of the HTTR-GT/H test plant be made after 3-4 years, after the HTTR will be restarted and the thermal load fluctuation tests using HTTR will be carried out. This report lists the members of the Evaluation Committee and outlines the method and procedure of the assessment. The assessment report by the Evaluation Committee is attached.
Inaba, Yoshitomo; Nishihara, Tetsuo
Annals of Nuclear Energy, 101, p.383 - 389, 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 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.
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) (CD-ROM), 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.
Inaba, Yoshitomo; Honda, Yuki; Nishihara, Tetsuo
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), 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.
Fukaya, Yuji; Nishihara, Tetsuo
Nuclear Engineering and Design, 307, p.188 - 196, 2016/10
Reduction of High Level Waste (HLW) and footprint in a geological repository due to high burn-up and high thermal efficiency of High Temperature Gas-cooled Reactor (HTGR) has been investigated. A helium-cooled and graphite-moderated commercial HTGR was designed as a Gas Turbine High Temperature Reactor (GTHTR300), and the features are significantly high burn-up of approximately 120 GWd/t, high thermal efficiency around 50%, and pin-in-block type fuel. The pin-in-block type fuel was employed to reduce processed graphite volume in reprocessing, and effective waste loading method for direct disposal is proposed by applying the feature in this study. As a result, it is found that the number of canisters and its repository footprint per electricity generation can be reduced by 60% compared with LWR representative case for direct disposal because of the higher burn-up, higher thermal efficiency, less TRU generation, and effective waste loading proposed in this study for HTGR. For disposal with reprocessing, the number of canisters and its repository footprint per electricity generation can be reduced by 30% compared with LWR because of the 30% higher thermal efficiency of HTGR.
Fukaya, Yuji; Tokuhara, Kazumi; Nishihara, Tetsuo
JAEA-Research 2016-008, 52 Pages, 2016/06
To investigate the xenon stability quantitatively, a study on stability criterion of xenon oscillation based on an analysis solution for HTGR design had been performed. Randall developed the stability criterion method of xenon oscillation based on an analysis solution. And, that have been employed for a LWR design. On the other hand, HTGR is also planted to design new type of reactors, such as Pu fueled reactor, and it is necessary to confirm the xenon stability of those new types of reactors. Then, we developed the criterion method based on the Randall's method termed D-XESC/A, and high xenon stability of HTGR and feasibility for Pu fueled reactor is confirmed by comparing with xenon stability of other types of reactors.
Ono, Masato; Iigaki, Kazuhiko; Shimazaki, Yosuke; Shimizu, Atsushi; Inoi, Hiroyuki; Tochio, Daisuke; Hamamoto, Shimpei; Nishihara, Tetsuo; Takada, Shoji; Sawa, Kazuhiro; et al.
Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 12 Pages, 2016/06
On March 11th, 2011, the Great East Japan Earthquake of magnitude 9.0 occurred. When the great earthquake occurred, the HTTR had been stopped under the periodic inspection and maintenance of equipment and instrument. In the great earthquake, the maximum seismic acceleration observed at the HTTR exceeded the maximum value in seismic design. The visual inspection of HTTR facility was carried out for the seismic integrity conformation of HTTR. The seismic analysis was also carried out using the observed earthquake motion at HTTR site to confirm the integrity of HTTR. The concept of comprehensive integrity evaluation for the HTTR facility is divided into two parts. One is the inspection of equipment and instrument. The other is the seismic response analysis using the observed earthquake. For the basic inspections of equipment and instrument were performed for all them related to the operation of reactor. The integrity of the facilities is confirmed by comparing the inspection results or the numerical results with their evaluation criteria. As the result of inspection of equipment and instrument and seismic response analysis, it was judged that there was no problem to operate the reactor, because there was no damage and performance deterioration, which affects the reactor operation. The integrity of HTTR was also supported by the several operations without reactor power in cold conditions of HTTR in 2011, 2013 and 2015.
Fukaya, Yuji; Nishihara, Tetsuo
JAEA-Research 2016-001, 23 Pages, 2016/05
A study on Correlation effect between elements of statistical hot spot factor for High Temperature Gas-cooled Reactor (HTGR) Design had been performed. Both of safety and reactor specification can be remained if the uncertainty is correctly propagated by revising hot spot factor. In this context, it is reported for light water reactor design that the propagated uncertainty can be reduced by statistical hot spot factors with numerical statistical approach, that is Monte Carlo method, because correlation effects for each factor can be considered. For HTGR with sleeve covered fuel, it is expected that the fuel temperature also reduces by employing the same approach because the gap between sleeve and fuel compact, which shows significant temperature increase, have direct correlation. In addition, Monte Carlo method treats correlation effect at the price of evaluating contribution of individual factor. Therefore, improved method based on conventional method has been developed in this study. Then, statistical hot spot factor for fuel temperature of HTGR was evaluated by Monte Carlo method and the improved method. As a result, it is not found significant difference between the result of the conventional method and the improved method. Moreover, usage of hot spot factor is investigated and we proposed new one reflecting the investigation.
Aihara, Jun; Ueta, Shohei; Nishihara, Tetsuo
JAEA-Technology 2015-040, 32 Pages, 2016/02
Original FORNAX-A is a calculation code for amount of fission product (FP) released from fuel rods of pin-in-type high temperature gas-cooled reactors (HTGRs). This report is for explanation what calculations become possible with minor changed FORNAX-A.
Fukaya, Yuji; Goto, Minoru; Nishihara, Tetsuo
JAEA-Research 2015-023, 44 Pages, 2016/02
A study on innovative High Temperature Gas-cooled Reactor (HTGR) to reduce generation of potential radiotoxicity had been performed. Unlike the Fast Breeder Reactor (FBR) and Accelerated Driven System (ADS), which can confine radioactive nuclides into its fuel cycle as multi-recycling and transmute, in this study we attempt to reduce the generation of the radiotoxicity itself by preventing the generation of Pu and MA, which is generated with the energy generation. In this context, we proposed the innovative HTGR that employs the Highly Enriched Uranium (HEU) fuel by removing U : source of the Pu and MA. However, there are the problems of fuel integrity, nuclear proliferation, nuclear self-regulation characteristics, and economy of electricity generation which are caused by employing HEU. For these problems, we investigated and proposed the solutions. Especially for the nuclear self-regulation characteristics, which were improved by adding Er, the optimized nuclear design was quantitatively determined and elucidated by the Bondarenko approach. As a result, it was confirmed that the proposed reactor can solves these problem for employing HEU fuel and the high specification and economy as same as those of standard HTGR fueled uranium.
Dipu, A. L.; Ohashi, Hirofumi; Hamamoto, Shimpei; Sato, Hiroyuki; Nishihara, Tetsuo
Annals of Nuclear Energy, 88, p.126 - 134, 2016/02
The tritium concentration in the high temperature engineering test reactor (HTTR) was measured during the high temperature continuous operation for 50 days. The tritium concentration in the primary helium gas increased after startup and reached a maximum value. It then decreased slightly over the course during the normal operation phase. Decrease of concentration of tritium in primary helium gas during the normal operation phase could be attributed to the effect of tritium chemisorption on graphite. The tritium concentration in the secondary helium gas showed a peak value during the power ramp up phase. Afterwards, it decreased gradually at the end of normal power operation. It was assessed that the concentration and total quantity of tritium in the secondary helium cooling system for the HTTR-Iodine Sulfur (IS) system can be maintained below the regulatory limits, which means the hydrogen production plant can be exempt from the safety function of the nuclear facility.
Fukaya, Yuji; Goto, Minoru; Nishihara, Tetsuo
Nuclear Engineering and Design, 293, p.30 - 37, 2015/11
The investigation on the erbium loading method to improve reactivity coefficients for Low Radiotoxic Spent Fuel High Temperature Gas-cooled Reactor (LRSF-HTGR) is performed. The fuel employs HEU to reduce toxicity generation from uranium-238. The reactivity coefficients show positive values without any additive. Then, the erbium is loaded in the core to obtain negative reactivity coefficient due to the large resonance peak of neutron capture reaction of erbium-167. The loading methods are investigated. The erbium is mixed into fuel kernel of CPF, loaded by binary packing with fuel particle and erbium particle, and embedded into the graphite shaft deployed center of fuel compact. It is found that the erbium loading causes negative reactivity as a moderator temperature reactivity, and it should be loaded into fuel pin elements for pin-in-block type fuel from the viewpoint of heat transfer. Moreover, the erbium should be incinerated slowly to obtain negative reactivity coefficient even at EOC. The loading method which effectively causes self-shielding should be selected to avoid to be incinerated with burn-up. The mechanism is elucidated by application of Bondarenko approach. As a result, it is conclude that the erbium embedded into graphite shaft is preferable for LRSF-HTGR to remain the reactivity coefficient negative at EOC.