High temperature gas-cooled reactors

Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.

High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02

https://doi.org/10.1016/C2018-0-05383-9

As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.

Uranium-based TRU multi-recycling with thermal neutron HTGR to reduce environmental burden and threat of nuclear proliferation

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

AA2017-0752.pdf:1.25MB

https://doi.org/10.1080/00223131.2018.1492983

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.

Optimization of disposal method and scenario to reduce high level waste volume and repository footprint for HTGR

Fukaya, Yuji; Goto, Minoru; Ohashi, Hirofumi; Nishihara, Tetsuo; Tsubata, Yasuhiro; Matsumura, Tatsuro

Annals of Nuclear Energy, 116, p.224 - 234, 2018/06

AA2017-0381.pdf:0.87MB

https://doi.org/10.1016/j.anucene.2018.02.031

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.

Study on innovative HTGR to reduce generation of potential radiotoxicity

Fukaya, Yuji; Goto, Minoru; Nishihara, Tetsuo

JAEA-Research 2015-023, 44 Pages, 2016/02

JAEA-Research-2015-023.pdf:2.13MB

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.

Development on nuclear design model for detailed design of clean burn HTGR

Fukaya, Yuji; Goto, Minoru; Nishihara, Tetsuo

JAEA-Technology 2015-017, 61 Pages, 2015/07

JAEA-Technology-2015-017.pdf:1.97MB

A development on nuclear design model for detailed design of Clean Burn HTGR had been performed. In the previous study, the fuel composition assumed in the study of Deep Burn proposed by GA in U.S. was employed. In the present study, that is estimated to reflect the situation of the nuclear fuel cycle in Japan. And, the evaluation method is refined from the viewpoint of traceability and a guarantee of quality. The deployment of control rod columns is investigated. Moreover, the Er loading is also investigated to obtain negative temperature coefficients in all range of operation. This model is developed for MVP code, which solves neutron transportation by Monte Carlo method. Validation of burn-up chain is also performed to adopt very high burn-up calculation. The core design is performed by COREBN code, which solves neutron diffusion equation by deterministic approach. Thus, the convertor which converts the cross section of MVP to COREBN is also developed.

Distribution of radioactive nuclides of boring core samples extracted from concrete structures of reactor buildings in the Fukushima Daiichi Nuclear Power Plant

Maeda, Koji; Sasaki, Shinji; Kumai, Misaki; Sato, Isamu; Suto, Mitsuo; Osaka, Masahiko; Goto, Tetsuo*; Sakai, Hitoshi*; Chigira, Takayuki*; Murata, Hirotoshi*

Journal of Nuclear Science and Technology, 51(7-8), p.1006 - 1023, 2014/07

https://doi.org/10.1080/00223131.2014.915769

Since the start of the severe accident at the Fukushima Daiichi Nuclear Power Plant in March 2011, concrete surfaces within the reactor buildings have been exposed to radioactive contaminants. Released radiation sources still remain too high to permit entry into some areas of the RBs to allow the damage to be assessed and to allow carrying out the restoration of lost safety functions, decommissioning activities, etc. In order to clarify the situation of this contamination in the RBs, 18 samples were subjected to analyses to determine the surface radionuclide concentrations and to characterize the radionuclide distributions in the samples. Decontamination tests on the sample of Unit 2 were conducted to reduce the levels of radioactivity present near the sample surface. As a result of the tests, the level of radioactivity of the sample was reduced with the removal of 97% of the contamination present near the sample surface.

Results of detailed analyses performed on boring cores extracted from the concrete floors of the Fukushima Daiichi Nuclear Power Plant reactor buildings

Maeda, Koji; Sasaki, Shinji; Kumai, Misaki; Sato, Isamu; Osaka, Masahiko; Fukushima, Mineo; Kawatsuma, Shinji; Goto, Tetsuo*; Sakai, Hitoshi*; Chigira, Takayuki*; et al.

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.272 - 277, 2013/09

Long-term high-temperature operation in the HTTR, 2; Core physics

Goto, Minoru; Fujimoto, Nozomu; Shimakawa, Satoshi; Tachibana, Yukio; Nishihara, Tetsuo; Iyoku, Tatsuo

Proceedings of 5th International Topical Meeting on High Temperature Reactor Technology (HTR 2010) (CD-ROM), 8 Pages, 2010/10

In the High Temperature Engineering Test Reactor (HTTR), which is a Japanese block-type HTGR, reactivity is controlled by control rods (CRs) and burnable poisons (BPs). The CRs insertion depth into the core should be retained shallow during burnup period, because the large insertion depth leads to significant disturbance of the power distribution, and consequently fuel temperature rises above the limit. Thus, the controllable reactivity with the CRs during operation is small, and then reactivity control through the burnup period largely depends on the BPs. It has not been confirmed an effectiveness of BPs on reactivity control on block-type HTGRs. The HTTR succeeded in long-term high temperature operation, and its burnup reached about 370EFPD. Thereby it became possible to confirm the effectiveness of BPs on reactivity control on the HTTR using its burnup data. We focused on a burnup change in the CRs insertion depth into the core to confirm whether the BPs functioned as designed. Additionally, we compared the change in the CRs insertion depths between analysis results and the experimental data to confirm validity of a whole core burnup calculation with the SRAC/COREBN. As a result, the experimental data showed that although the CRs insertion depth into the core was increased with burnup, it was retained the allowable depth. Meanwhile, the analysis result of the CRs insertion depth was in good agreement with the experimental data.

Preliminary study on HTTR tests for development of commercial HTGRs

Goto, Minoru; Takamatsu, Kuniyoshi; Nakagawa, Shigeaki; Ueta, Shohei; Hamamoto, Shimpei; Ohashi, Hirofumi; Furusawa, Takayuki; Saito, Kenji; Shimazaki, Yosuke; Nishihara, Tetsuo

JAEA-Technology 2009-053, 48 Pages, 2009/10

JAEA-Technology-2009-053.pdf:3.41MB

Preliminary studies on the HTTR (High Temperature engineering Test Reactor) tests were conducted to obtain characteristics and demonstration data which were required to develop commercial HTGRs (high temperature gas-cooled reactors). The tests proposed in this study are as follows: nuclear heat supply characteristics tests, burned core tests, reactivity insertion tests, safety demonstration tests, fuel characteristics tests, annular core tests, fuel failure tests, tritium measurement tests, and health confirmation tests of high temperature equipments. Requirements for a development of commercial HTGRs and confirmation methods of the requirements by the HTTR tests were summarized. Preliminary analyses were performed for the burned core test and the safety demonstration test to obtain prediction data, which is compared with experimental data. Additionally, a feasibility analysis was performed on four types annular cores, which is composed of the HTTR's fresh fuels, from the point of view of shutdown margin and excess reactivity.

Examination on small-sized cogeneration HTGR for developing countries

Sakaba, Nariaki; Tachibana, Yukio; Shimakawa, Satoshi; Ohashi, Hirofumi; Sato, Hiroyuki; Yan, X.; Murakami, Tomoyuki; Ohashi, Kazutaka; Nakagawa, Shigeaki; Goto, Minoru; et al.

JAEA-Technology 2008-019, 57 Pages, 2008/03

JAEA-Technology-2008-019.pdf:8.59MB

The small-sized and safe cogeneration High Temperature Gas-cooled Reactor (HTGR) that can be used not only for electric power generation but also for hydrogen production and district heating is considered one of the most promising nuclear reactors for developing countries where sufficient infrastructure such as power grids is not provided. Thus, the small-sized cogeneration HTGR, named High Temperature Reactor 50-Cogeneration (HTR50C), was studied assuming that it should be constructed in developing countries. Specification, equipment configuration, etc. of the HTR50C were determined, and economical evaluation was made. As a result, it was shown that the HTR50C is economically competitive with small-sized light water reactors.