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Journal Articles

Vertical distributions of Iodine-129 and iodide in the Chukchi Sea and Bering Sea

Miwa, Kazuji; Obata, Hajime*; Suzuki, Takashi

Journal of Nuclear Science and Technology, 57(5), p.537 - 545, 2020/05

 Times Cited Count:1 Percentile:62.32(Nuclear Science & Technology)

This study investigated the vertical distribution of Iodine-129 ($$^{129}$$I) which is mainly produced by European nuclear reprocessing plants in the Chukchi Sea and Bering Sea. $$^{129}$$I was found to be distributed almost uniformly in fallout level, and an increasing in $$^{129}$$I concentration levels caused by high $$^{129}$$I water inflow from the Atlantic Ocean was not observed. Additionally, we revealed the vertical distribution of iodide, one chemical form of iodine, from the Bering Shelf area to the Chukchi Sea for the first time. The increasing tendency of iodide near sea bottom was observed.

Journal Articles

Promising neutron irradiation applications at the high temperature engineering test reactor

Ho, H. Q.; Honda, Yuki*; Hamamoto, Shimpei; Ishii, Toshiaki; Takada, Shoji; Fujimoto, Nozomu*; Ishitsuka, Etsuo

Journal of Nuclear Engineering and Radiation Science, 6(2), p.021902_1 - 021902_6, 2020/04

JAEA Reports

Fission product chemistry database ECUME version 1.1

Development Group for LWR Advanced Technology

JAEA-Data/Code 2019-017, 59 Pages, 2020/03


ECUME ($$underline{E}$$ffective $$underline{C}$$hemistry database of fission products $$underline{U}$$nder $$underline{M}$$ultiphase r$$underline{E}$$action) is the database for the analyses of FP chemistry which strongly affects all the FP behaviors in a severe accident (SA) of nuclear facility like LWR. ECUME consists of three kinds of datasets: CRK (dataset for $$underline{C}$$hemical $$underline{R}$$eaction $$underline{K}$$inetics), EM ($$underline{E}$$lemental $$underline{M}$$odel set) and TD ($$underline{T}$$hermo$$underline{D}$$ynamic dataset). The present version of ECUME is prepared especially for the more accurate evaluation of cesium and iodine distribution in a reactor and release amount into an environment which should be of crucial importance towards the decommissioning of Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company Holdings (1F) and the enhancement of LWR safety after the 1F SA.

Journal Articles

R&D status of hydrogen production test using IS process test facility made of industrial structural material in JAEA

Noguchi, Hiroki; Takegami, Hiroaki; Kamiji, Yu; Tanaka, Nobuyuki; Iwatsuki, Jin; Kasahara, Seiji; Kubo, Shinji

International Journal of Hydrogen Energy, 44(25), p.12583 - 12592, 2019/05

 Times Cited Count:1 Percentile:86.72(Chemistry, Physical)

JAEA has been conducting R&D on thermochemical water-splitting hydrogen production IS process to develop one of heat applications of high-temperature gas-cooled reactor. A test facility was constructed using corrosion-resistant industrial materials to verify integrity of the IS process components and to demonstrate continuous and stable hydrogen production. The performance of components installed in each section was confirmed. Subsequently, a trial operation of integration of the processing sections was successfully carried out for 8 hours with hydrogen production rate of approximately 10 NL/h. After that, hydrogen production operation was extended to 31 hours (approximately hydrogen production rate of 20 NL/h) by introducing a corrosion-resistance pump system with a developed shaft seal technology.

Journal Articles

Experimental determination of the photooxidation of aqueous I$$^{-}$$ as a source of atmospheric I$$_{2}$$

Watanabe, Kosuke*; Matsuda, Shohei; Cuevas, C. A.*; Saiz-Lopez, A.*; Yabushita, Akihiro*; Nakano, Yukio*

ACS Earth and Space Chemistry (Internet), 3(4), p.669 - 679, 2019/04

 Times Cited Count:2 Percentile:54.32(Chemistry, Multidisciplinary)

The photooxidation of aqueous iodide ions (I$$^{-}$$$$_{(aq)}$$) at sea surface results in the emission of gaseous iodine molecules (I$$_{2}$$$$_{(g)}$$) into the atmosphere. It plays a certain role in the transport of iodine from ocean to the atmosphere in the natural cycle of iodine. In this study, we determined the photooxidation parameters, the molar absorption coefficient ($$varepsilon$$$$_{iodide}$$($$lambda$$)) and the photooxidative quantum yields ($$Phi$$$$_{iodide}$$($$lambda$$)) of I$$^{-}$$$$_{(aq)}$$, in the range of 290-500 nm. Through the investigation of the influence of pH and dissolved oxygen (DO) on $$Phi$$$$_{iodide}$$($$lambda$$), the subsequent emission rates of I$$_{2}$$$$_{(g)}$$ following the photooxidation of I$$^{-}$$$$_{(aq)}$$ in deionized water solution (pH 5.6, DO 7.8 mg L$$^{-1}$$) and artificial seawater solution (pH 8.0, DO 7.0 mg L$$^{-1}$$) were estimated. A global chemistry-climate model employed herein to assess the I$$_{2}$$$$_{(g)}$$ ocean emission on a global scale indicated that the photooxidation of I$$^{-}$$$$_{(aq)}$$ by solar light can enhance the atmospheric iodine budget by up to $$sim$$8% over some oceanic regions.

Journal Articles

Chemical reaction kinetics dataset of Cs-I-B-Mo-O-H system for evaluation of fission product chemistry under LWR severe accident conditions

Miyahara, Naoya; Miwa, Shuhei; Horiguchi, Naoki; Sato, Isamu*; Osaka, Masahiko

Journal of Nuclear Science and Technology, 56(2), p.228 - 240, 2019/02

 Times Cited Count:4 Percentile:15.49(Nuclear Science & Technology)

In order to improve LWR source term under severe accident conditions, the first version of a fission product (FP) chemistry database named "ECUME" was developed. The ECUME is intended to include major chemical reactions and their effective kinetic constants for representative SA sequences. It is expected that the ECUME can serve as a fundamental basis from which FP chemical models in the SA analysis codes can be elaborated. The implemented chemical reactions in the first version were those for representative gas species in Cs-I-B-Mo-O-H system. The chemical reaction kinetic constants were evaluated from either literature data or calculated values using ab-initio calculations. The sample chemical reaction calculation using the presently constructed dataset showed meaningful kinetics effects at 1000 K. Comparison of the chemical equilibrium compositions by using the dataset with those by chemical equilibrium calculations has shown rather good consistency for the representative Cs-I-B-Mo-O-H species. From these results, it was concluded that the present dataset should be useful to evaluate FP chemistry in Cs-I-B-Mo-O-H system under LWA SA conditions.

Journal Articles

Synthesis and characterization of CeO$$_{2}$$-based simulated fuel containing CsI

Takamatsu, Yuki*; Ishii, Hiroto*; Oishi, Yuji*; Muta, Hiroaki*; Yamanaka, Shinsuke*; Suzuki, Eriko; Nakajima, Kunihisa; Miwa, Shuhei; Osaka, Masahiko; Kurosaki, Ken*

Nippon Genshiryoku Gakkai Wabun Rombunshi, 17(3/4), p.106 - 110, 2018/12

In order to establish the synthesis method of simulated fuel contacting Cesium (Cs) which is required for the evaluation of physical/chemical characteristics in fuel and release behavior of Cs, sintering tests of the cerium dioxide (CeO$$_{2}$$) based simulated fuels containing Cesium iodide (CsI) are performed by using spark plasma sintering (SPS) method. The sintered CeO$$_{2}$$ pellets with homogeneous distribution of several micro meter of CsI spherical precipitates were successfully obtained by optimizing SPS conditions.

Journal Articles

Feasibility study of large-scale production of iodine-125 at the high temperature engineering test reactor

Ho, H. Q.; Honda, Yuki*; Hamamoto, Shimpei; Ishii, Toshiaki; Fujimoto, Nozomu*; Ishitsuka, Etsuo

Applied Radiation and Isotopes, 140, p.209 - 214, 2018/10

 Times Cited Count:3 Percentile:42.21(Chemistry, Inorganic & Nuclear)

Journal Articles

Conceptual design of the iodine-sulfur process flowsheet with more than 50% thermal efficiency for hydrogen production

Kasahara, Seiji; Imai, Yoshiyuki; Suzuki, Koichi*; Iwatsuki, Jin; Terada, Atsuhiko; Yan, X.

Nuclear Engineering and Design, 329, p.213 - 222, 2018/04

 Times Cited Count:4 Percentile:31.88(Nuclear Science & Technology)

A conceptual design of a practical large scale plant of the thermochemical water splitting iodine-sulfur (IS) process flowsheet was carried out as a heat application of JAEA's commercial high temperature gas cooled reactor GTHTR300C plant design. Innovative techniques proposed by JAEA were applied for improvement of hydrogen production thermal efficiency; depressurized flash concentration H$$_{2}$$SO$$_{4}$$ using waste heat from Bunsen reaction, prevention of H$$_{2}$$SO$$_{4}$$ vaporization from a distillation column by introduction of H$$_{2}$$SO$$_{4}$$ solution from a flash bottom, and I$$_{2}$$ condensation heat recovery in an HI distillation column. Hydrogen of about 31,900 Nm$$^{3}$$/h would be produced by 170 MW heat from the GTHTR300C. A thermal efficiency of 50.2% would be achievable with incorporation of the innovative techniques and high performance HI concentration and decomposition components and heat exchangers expected in future R&D.

Journal Articles

R&D status in thermochemical water-splitting hydrogen production iodine-sulfur process at JAEA

Noguchi, Hiroki; Takegami, Hiroaki; Kasahara, Seiji; Tanaka, Nobuyuki; Kamiji, Yu; Iwatsuki, Jin; Aita, Hideki; Kubo, Shinji

Energy Procedia, 131, p.113 - 118, 2017/12

 Times Cited Count:10 Percentile:0.31

The IS process is the most deeply investigated thermochemical water-splitting hydrogen production cycle. It is in a process engineering stage in JAEA to use industrial materials for components. Important engineering tasks are verification of integrity of the total process and stability of hydrogen production in harsh environment. A test facility using corrosion-resistant materials was constructed. The hydrogen production ability was 100 L/h. Operation tests of each section were conducted to confirm basic functions of reactors and separators, etc. Then, a trial operation for integration of the sections was successfully conducted to produce hydrogen of about 10 L/h for 8 hours.

Journal Articles

Development of experimental and analytical technologies for fission product chemistry under LWR severe accident condition

Miyahara, Naoya; Miwa, Shuhei; Nakajima, Kunihisa; Osaka, Masahiko

Proceedings of 2017 Water Reactor Fuel Performance Meeting (WRFPM 2017) (USB Flash Drive), 9 Pages, 2017/09

This paper presents the development of a reproductive experimental setup for FP release and transport and an analysis tool considering chemical reaction kinetics for the construction of the FP chemistry database. The performance test of the reproductive experimental setup TeRRa using CsI compounds show that TeRRa can reproduce well a FP chemistry-related behavior such as aerosol formation, growth and deposition behavior. An analytical tool has been developed based on the commercial ANSYS-FLUENT code. Some additional models was added to evaluate detailed FP chemistry during release and transport in this study. A test analysis simulating the CsI heating test in steam atmosphere was carried out to demonstrate the performance of the improved code. The result shows the appropriateness of the additional models.

Journal Articles

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) (CD-ROM), 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.

Journal Articles

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) (CD-ROM), 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.

Journal Articles

Effects of constituents of seawater on formation of volatile iodine by aqueous phase radiation chemistry

Hata, Kuniki; Kido, Kentaro; Nishiyama, Yutaka; Maruyama, Yu

NEA/CSNI/R(2016)5 (Internet), p.196 - 203, 2016/05

Journal Articles

Formation and release of molecular iodine in aqueous phase chemistry during severe accident with seawater injection

Kido, Kentaro; Hata, Kuniki; Maruyama, Yu; Nishiyama, Yutaka; Hoshi, Harutaka*

NEA/CSNI/R(2016)5 (Internet), p.204 - 212, 2016/05

JAEA Reports

Study on release behavior of radioiodine from fuel solution under criticality accident condition

Tashiro, Shinsuke; Abe, Hitoshi

JAEA-Technology 2015-044, 20 Pages, 2016/03


In order to estimate public dose under a criticality accident in fuel solution of a fuel reprocessing plant, release behavior of radioiodine from the fuel solution to atmosphere is very important. In this report, time evolution of $$^{133}$$I concentration in gas phase of TRACY core tank was measured until the concentration in the solution decreased. Furthermore, cumulative release ratio (CRR) and release rate (RR) from the solution to the atmosphere of radioiodine were evaluated by applying previously-reported evaluation model. As a result, for the case of short transient criticality, RR of $$^{133}$$I became maximum at 1 hour later from the ending and almost constant after 8 hour later. Furthermore, relationship of each elapsed time between total fission number and release rate of $$^{133}$$I could be derived. On the other hand, for the case of long criticality excursion, such as JCO criticality accident, the CRR and RR of radioiodine increased monotonously with time.

Journal Articles

Hard X-ray photoelectron spectroscopy study for transport behavior of CsI in heating test simulating a BWR severe accident condition; Chemical effects of boron vapors

Okane, Tetsuo; Kobata, Masaaki; Sato, Isamu*; Kobayashi, Keisuke*; Osaka, Masahiko; Yamagami, Hiroshi

Nuclear Engineering and Design, 297, p.251 - 256, 2016/02

 Times Cited Count:1 Percentile:83.64(Nuclear Science & Technology)

Journal Articles

Study on safety evaluation for nuclear fuel cycle facility under accident conditions

Abe, Hitoshi; Tashiro, Shinsuke; Morita, Yasuji

JAERI-Conf 2005-007, p.199 - 204, 2005/08

Source term data for estimating release behavior of radioactive nuclides is necessary to evaluate synthetic safety of nuclear fuel cycle facility under accident conditions, such as fire and criticality. In JAERI, the data has been obtained by performing some demonstration tests. In this paper, the data for the criticality accident in fuel solution obtained from the TRACY experiment, will be mainly reviewed. At 4.5 h after the transient criticality, the release ratio of the iodine were about 0.2% for re-insertion of transient rod at just after transient criticality and about 0.9% for not re-insertion. Similarly the release coefficient and release ratio for Xe were estimated. It was proved that the release ratio of Xe-141 from the solution was over 90% in case that the inverse period was over about 100 (1/s). Furthermore, outline of the study on the fire accident as future plan will be also mentioned.

Journal Articles

JAERI's hot stuff

Sakaba, Nariaki; Tachibana, Yukio; Onuki, Kaoru; Komori, Yoshihiro; Ogawa, Masuro

Nuclear Engineering International, 50(612), p.20 - 22, 2005/07

The HTTR (High Temperature Engineering Test Reactor) at Japan Atomic Energy Research Institute's Oarai Research Establishment attained its maximum reactor-outlet coolant temperature of 950$$^{circ}$$C in April 2004 and ready to connect nuclear heat for industrial applications. The hydrogen production system by thermochemical water-splitting Iodine Sulphur cycle is also developing and succeeded to produce 30 normal L/h hydrogen in a closed cycle in June 2004.

Journal Articles

Model testing using data on $$^{131}$$I released from Hanford

Thiessen, K. M.*; Napier, B. A.*; Filistovic, V.*; Homma, Toshimitsu; Kany$'a$r, B*; Krajewski, P.*; Kryshev, A. I.*; Nedveckaite, T.*; N$'e$nyei, A.*; Sazykina, T. G.*; et al.

Journal of Environmental Radioactivity, 84(2), p.211 - 224, 2005/00

 Times Cited Count:7 Percentile:80.44(Environmental Sciences)

The Hanford test scenario described an accidental release of $$^{131}$$I to the environment from the Hanford Purex Chemical Separations Plant in September 1963. Based on monitoring data collected after the release, this scenario was used by the Dose Reconstruction Working Group of BIOMASS. Predicted doses to actual children with high milk consumption ranged from 0.006 to 2 mSv. The predicted deposition at any given location varied among participants by a factor of 5 to 80. Predicted ingestion doses for children, normalized for predicted deposition, varied by about a factor of 10. The exercise provided an opportunity for comparison of assessment methods and conceptual approaches, testing model predictions against measurements, and identifying the most important contributors to uncertainty in the assessment result. Key factors affecting predictions included the approach to handling incomplete data, interpretation of input information, selection of parameter values, adjustment of models for sitespecific conditions, and treatment of uncertainties.

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