Miwa, Shuhei; Nakajima, Kunihisa; Miyahara, Naoya; Nishioka, Shunichiro; Suzuki, Eriko; Horiguchi, Naoki; Liu, J.; Miradji, F.; Imoto, Jumpei; Mohamad, B. A.; et al.
Mechanical Engineering Journal (Internet), 7(3), p.19-00537_1 - 19-00537_11, 2020/06
We constructed the fission product (FP) chemistry database named ECUME for LWR severe accident. This version of ECUME is equipped with dataset of the chemical reactions and their kinetics constants for the reactions of cesium(Cs)-iodine(I)-boron(B)-molybdenum(Mo)-oxygen(O)-hydrogen(H) system in gas phase, the elemental model for the high temperature chemical reaction of Cs with stainless steel applied as the structural material in a reactor, and thermodynamic data for CsBO vapor species and solids of CsSiO and CsFeSiO for these chemical reactions. The ECUME will provide estimation of Cs distribution due to the evaluation of effects of interaction with BWR control material B and stainless steel on Cs behavior in the Fukushima Daiichi Nuclear Power Station.
Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*
JAEA-Review 2019-035, 61 Pages, 2020/03
JAEA/CLADS, had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aims to contribute to solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Basic Research on the Stability of Fuel Debris Including Alloy Phase". In the present study, we focus on fuel debris consisting of oxide phase and alloy phase generated by the high-temperature chemical reaction between structure materials (SUS pipes, pressure vessels, etc.) and fuels (melted fuels, claddings components, etc.). We synthesize the simulated debris of UO-SUS system and UO-Zr(ZrO)-SUS system by high-temperature heat treatment, and measure their chemical property and dissolution behavior in water. Also, we will conduct research and development to spectroscopically analyze secular changes of oxide phase and alloy phase in the simulated debris.
Development Group for LWR Advanced Technology
JAEA-Data/Code 2019-017, 59 Pages, 2020/03
ECUME (ffective hemistry database of fission products nder ultiphase raction) 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 hemical eaction inetics), EM (lemental odel set) and TD (hermoynamic 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.
Nakatsuka, Toru; Maeda, Toshikatsu; Sugiyama, Tomoyuki; Maruyama, Yu
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.1650 - 1656, 2019/08
The OECD/NEA is launching a new project named "Analysis of Information from Reactor Buildings and Containment Vessels of Fukushima Daiichi Nuclear Power Station (ARC-F)" Project. This project will serve as the successor to the precedent NEA project, "Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Station (BSAF) Phase II" which investigated the accident scenarios, associated fission products behavior in the damaged units and source term to the environment. The ARC-F project comprises three tasks: Task 1: Refinement of analysis for accident scenarios and associated fission product transportation and dispersion; Task 2: Compilation and management of data and information; and Task 3: Discussion for future long-term project. Japan Atomic Energy Agency is the operating agent, responsible to lead all the tasks. Duration of the project is from January 2019 to December 2021 and the final report is planned to be published in 2022.
Miwa, Shuhei; Miyahara, Naoya; Nakajima, Kunihisa; Nishioka, Shunichiro; Suzuki, Eriko; Horiguchi, Naoki; Liu, J.; Miradji, F.; Imoto, Jumpei; Mohamad, B. A.; et al.
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05
We constructed the first version of fission product (FP) chemistry database named ECUME for LWR severe accident. The first version of ECUME is equipped with dataset of the chemical reactions and their kinetics constants for the reactions of cesium(Cs)-iodine(I)-boron(B)-molybdenum(Mo)-oxygen(O)-hydrogen(H) system in gas phase, the elemental model for the high temperature chemical reaction of Cs with stainless steel, and thermodynamic data for CsBO vapor species and solids of CsSiO and CsFeSiO. The ECUME will provide more accurate estimation of Cs distribution due to the evaluation of effects of interaction with BWR control material B and stainless steel on Cs behavior in the Fukushima Daiichi Nuclear Power Station.
Miyahara, Naoya; Miwa, Shuhei; Horiguchi, Naoki; Sato, Isamu*; Osaka, Masahiko
Journal of Nuclear Science and Technology, 56(2), p.228 - 240, 2019/02
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.
Nakamura, Shoji; Kimura, Atsushi; Hales, B. P.; Iwamoto, Osamu; Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*
JAEA-Conf 2018-001, p.199 - 203, 2018/12
Study on cross-section measurements has been promoted for Cs among long-lived fission products in ImPACT Project. The feasibility study on Se sample preparation also has been conducted to measure its cross sections in future. During the feasibility study, we started the neutron-capture cross-section measurements of stable Se isotopes. This paper reports research progresses on preparation of a radioactive Cs sample, neutron irradiation experiments with the Cs sample, and cross-section measurements of stable Se isotopes.
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) based simulated fuels containing Cesium iodide (CsI) are performed by using spark plasma sintering (SPS) method. The sintered CeO pellets with homogeneous distribution of several micro meter of CsI spherical precipitates were successfully obtained by optimizing SPS conditions.
Aihara, Jun; Ueta, Shohei; Goto, Minoru; Inaba, Yoshitomo; Shibata, Taiju; Ohashi, Hirofumi
JAEA-Technology 2018-002, 70 Pages, 2018/06
HTFP code is code for calculation of additional release amount of fission product (FP) from fuel rod in high temperature gas-cooled reactor (HTGR) after stop of fission. Minory changed Fornax-A code also can calculate that. Therefore, release behavior of Cs calculated with HTFP code was compared with that calculated with minory modified FORNAX-A code in this report. Release constants of Cs evaluated with minory modified FORNAX-A code are rather different from default values for HTFP code.
Shiotsu, Hiroyuki; Ishikawa, Jun; Sugiyama, Tomoyuki; Maruyama, Yu
Journal of Nuclear Science and Technology, 55(4), p.363 - 373, 2018/04
Nakamura, Shoji; Kimura, Atsushi; Hales, B. P.; Iwamoto, Osamu; Tsubata, Yasuhiro; Matsumura, Tatsuro; Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*
JAEA-Conf 2017-001, p.15 - 22, 2018/01
Neutron nuclear data of long lived fission products (LLFPs) have been required as basic data for the technology of reduce environmental impact involved in high level radioactive wastes (HLW). The innovative large project called by "Impusing Paradigm Change through Disruptive Technologies Program: ImPACT" have been started from October, 2014. In the ImPACT project, some research groups of JAEA engaged in the Project No.2 (Nuclear Reaction Data Measurements), and have started measurements of neutron capture cross-section at J-PARC/MLF/ANNRI. In our research, we selected cesium-135 (Cs) nuclide (half life: 2.310 yr.) among LLFPs in the HLW, and decided to measure the neutron capture cross-sections of Cs. When measurement, the Cs sample might contained cecium-137 (Cs) as impurities because it's impossible to chemically separate each other. To measure the cross-sections of Cs, there should be also needed to know the cross-sections of Cs. In this work, sample maintenance also has been examined especially for selen-79 (Se) nuclide among LLFPs having difficulty in sample preparations. In this oral session, the outline of our research project will be presented together with a research motivation, situations of past reported data, total schedules, progress, future plans, and some of high light data for neutron capture cross-section measurements.
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.
Zheng, X.; Ishikawa, Jun; Sugiyama, Tomoyuki; Maruyama, Yu
Nuclear Engineering and Technology, 49(2), p.434 - 441, 2017/03
Di Lemma, F. G.; Nakajima, Kunihisa; Yamashita, Shinichiro; Osaka, Masahiko
Journal of Nuclear Materials, 484, p.174 - 182, 2017/02
Chemisorption phenomena can affect fission products retention in the nuclear reactor vessel during a Severe Accident (SA). This paper will describe the influence of molybdenum contained in type 316 stainless steel (SS) on Cs chemisorption. Our experiments showed the formation of Cs-Mo compounds in addition to CsFeSiO, observed previously on SS304. The results of high temperature stability tests on the deposits are also presented. These tests aimed at simulating the revaporization of FP from structural materials during a SA. From our results, it can be inferred that Cs-Mo deposits may revaporize, contributing as a delayed source to the radioactive release.
Osaka, Masahiko; Miwa, Shuhei; Nakajima, Kunihisa; Di Lemma, F. G.*; Suzuki, Chikashi; Miyahara, Naoya; Kobata, Masaaki; Okane, Tetsuo; Suzuki, Eriko
JAEA-Review 2016-026, 32 Pages, 2016/12
A fundamental research program on fission product (FP) chemistry has started since 2012 for the purpose of establishment of a FP chemistry database in each region of LWR under severe accident and improvement of FP chemical models based on the database. Research outputs are reflected as fundamental knowledge to both the research and development of decommissioning of Fukushima Daiichi Nuclear Power Station (1F) and enhancement of LWR safety. Four research items have thus been established considering the specific issues of 1F and the priority in the source term research area, as follows: effects of boron (B) release kinetics and thermal-hydraulic conditions on FP behavior, cesium (Cs) chemisorption and reactions with structural materials, enlargement of a thermodynamic and thermophysical properties database for FP compounds and development of experimental and analytical techniques for the reproduction of FP behavior and for direct measurement methods of chemical form of FP compounds. In this report, the research results and progress for the year 2015 are described. The main accomplishment was the installation of a reproductive test facility for FP release and transport behavior. Moreover, basic knowledge about the Cs chemisorption behavior was also obtained. In addition to the four research items, a further research item is being considered for deeper interpretation of FP behavior by the analysis of samples outside of the 1F units.
Zheng, X.; Ishikawa, Jun; Sugiyama, Tomoyuki; Maruyama, Yu
Proceedings of 13th Probabilistic Safety Assessment and Management Conference (PSAM-13) (USB Flash Drive), 10 Pages, 2016/10
Research Team for Fission Product Behavior
JAEA-Review 2016-012, 17 Pages, 2016/07
The severe accident (SA) of Fukushima Daiichi Nuclear Power Station (1F) has given rise to enlarged research needs for the improvement of the source term assessment. Fission Product (FP) related researches, however, have not been widely conducted in Japan for many years, thus a framework for such research is not so robust. The Collaborative Laboratories for Advanced Decommissioning Science (CLADS) workshop held in November 2015 was an important opportunity to gain the state of art knowledge on FP and to start discussion between worldwide experts on innovative solution for 1F issues. This report describes the outcomes of FP session conducted in the CLADS workshop. It was pointed out during the workshop that further analyses were needed to properly understand the phenomena that occurred in 1F. The establishment of a Japanese FP platform is here proposed to respond to 1F issues effectively as a means to coordinate the national research efforts and increase communication between worldwide stakeholders. The FPs studies conducted in this frame will provide important information for the decommissioning of 1F, and will be also of great help for the international community to progress the knowledge on FPs behavior. Finally their outcomes could contribute in establishing improved SA management measures.
Yamane, Yuichi; Amano, Yuki; Tashiro, Shinsuke; Abe, Hitoshi; Uchiyama, Gunzo; Yoshida, Kazuo; Ishikawa, Jun
Journal of Nuclear Science and Technology, 53(6), p.783 - 789, 2016/06
The release behavior of radioactive materials from high active liquid waste (HALW) has been experimentally investigated under boiling accident conditions. In the experiments using HALW obtained through laboratory scale reprocessing, release ratio was measured for the FP nuclides such as Ru, Tc, Cs, Sr, Nd, Y, Mo, Rh and actinides such as Cm, Am. As a result, the release ratio was 0.20 for Ru and 1 for the FP and Ac nuclides. Ru was released into the gas phase in the form of both mist and gas. For its released amount, weak dependency was found to the initial concentration in the test solution. The release ratio decreased with the initial concentration. For other FP nuclides and actinides as non-volatile, released into the gas phase in the form of mist, the released amount increased with the initial concentration. The release ratio of Ru and NOx concentration increased with temperature of the test solutions. They were released almost at the same temperature between 200 and 300C. Size distribution of the mist and other particle was measured.
Di Lemma, F. G.; Miwa, Shuhei; Osaka, Masahiko
JAEA-Review 2016-007, 27 Pages, 2016/03
During a nuclear power plant Severe Accident, complex boron melts can be formed, due to interaction of the control rods with the cladding materials. These can affect ultimately the source term assessment. This review will describe the results of previous studies on boron carbide/stainless steel/Zircaloy (BC/SS/Zry) melts, which will finally provide guidance for the needs of future experiments. This review showed that models for the behavior of complex BC/SS/Zry melts are limited, and unsuccessful in simulating core degradation, thus the improvement of the database for BC/SS/Zry melts is needed. Our experimental plan aims in providing thermodynamics and kinetics models for such melts, with the final aim of improving boron modelling in SA codes analysis and of understanding its effect on fission products behavior.
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.