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JAEA Reports

Analysis of risk reduction effect of supposed steam condenser implementation as accident measure for accident of evaporation to dryness by boiling of reprocessed high level liquid waste

Yoshida, Kazuo; Tamaki, Hitoshi; Hiyama, Mina*

JAEA-Research 2021-013, 20 Pages, 2022/01

JAEA-Research-2021-013.pdf:2.35MB

An accident of evaporation to dryness by boiling of high level liquid waste (HLLW) is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, volatile radioactive materials, such as ruthenium (Ru) are released from the tanks with water and nitric-acid mixed vapor into atmosphere. An idea has been proposed to implement a steam condenser as an accident countermeasure. This measure is expected to prevent nitric acid steam diffusing in facility building and to increase gaseous Ru trapping ratio into condensed water. A simulation study has been carried out with a hypothetical typical facility building to analyze the efficiency of steam condenser. In this study, SCHERN computer code simulates chemical behaviors of Ru in nitrogen oxide, nitric acid and water mixed vapor based on the conditions obtained from simulation with thermal-hydraulic computer code MELCOR. The effectiveness of steam condenser has been analyzed quantitively in preventing mixed vapor diffusion and gaseous Ru trapping effect. Some issues to be solved in analytical model has been also clarified in this study.

JAEA Reports

Analysis of behavior of Ru with nitrogen oxide chemical behavior in accident of evaporation to dryness by boiling of reprocessed high level liquid waste

Yoshida, Kazuo; Tamaki, Hitoshi; Hiyama, Mina*

JAEA-Research 2021-005, 25 Pages, 2021/08

JAEA-Research-2021-005.pdf:2.91MB

An accident of evaporation to dryness by boiling of high level liquid waste (HLLW) is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, volatile radioactive materials, such as ruthenium (Ru) are released from the tanks with water and nitric-acid mixed vapor into atmosphere. Accurate quantitative estimation of released Ru is one of the important issues for risk assessment of those facilities. To resolve this issue, an empirical correlation equation of Ru mass transfer coefficient across the vapor-liquid surface, which can be useful for quantitative simulation of Ru mitigating behavior, has been obtained from data analyses of small-scale experiments conducted to clarify gaseous Ru migrating behavior under steam-condensing condition. A simulation study has been also carried out with a hypothetical typical facility building successfully to demonstrate the feasibility of quantitative estimation of amount of Ru migrating in the facility using the obtained correlation equation implemented in SCHERN computer code which simulates chemical behaviors of nitrogen oxide based on the condition also simulated thermal-hydraulic computer code.

JAEA Reports

SCHERN-V2: Technical guide of computer program for chemical behavior in accident of evaporation to dryness by boiling of reprocessed high level liquid waste in Fuel Reprocessing Facilities

Yoshida, Kazuo; Tamaki, Hitoshi; Hiyama, Mina*

JAEA-Data/Code 2021-008, 35 Pages, 2021/08

JAEA-Data-Code-2021-008.pdf:3.68MB

An accident of evaporation to dryness by boiling of high level liquid waste (HLLW) is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, volatile radioactive materials, such as ruthenium (Ru) are released from the tanks with water and nitric-acid mixed vapor into atmosphere. In addition to this, nitrogen oxides (NO$$_{rm x}$$) are also released formed by the thermal decomposition of metal nitrates of fission products (FP) in HLLW. It has been observed experimentally that NOx affects to the migration behavior of Ru at the anticipated atmosphere condition in cells and/or compartments of the facility building. Chemical reactions of NO$$_{rm x}$$ with water and nitric acid are also recognized as the complex phenomena to undergo simultaneously in the vapor and liquid phases. The analysis program, SCHERN has been under developed to simulate chemical behavior including Ru coupled with the thermo-hydraulic condition in the flow paths in the facility building. This technical guide for SCHERN-V2 presents the overview of covered accident, analytical models including newly developed models, differential equations for numerical solution, and user instructions.

JAEA Reports

SCHERN: Analysis program for chemical behavior of nitrogen oxide in accident of evaporation to dryness by boiling of reprocessed high level liquid waste in Fuel Reprocessing Facilities

Hiyama, Mina*; Tamaki, Hitoshi; Yoshida, Kazuo

JAEA-Data/Code 2019-006, 17 Pages, 2019/07

JAEA-Data-Code-2019-006.pdf:1.84MB

An accident of evaporation to dryness by boiling of high level liquid waste (HLLW) is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, volatile radioactive materials, such as ruthenium (Ru) are released from the tanks with water and nitric-acid mixed vapor into atmosphere. In addition to this, nitrogen oxides (NOx) are also released formed by the thermal decomposition of metal nitrates of fission products (FP) in HLLW. It has been observed experimentally that NOx affects strongly to the transport behavior of Ru at the anticipated atmosphere condition in cells and/or compartments of the facility building. Chemical reactions of NOx with water and nitric acid are also recognized as the complex phenomena to undergo simultaneously in the vapor and liquid phases. An analysis program has been developed to simulate chemical reaction coupled with the thermo-hydraulic condition in the flow paths in the facility building.

JAEA Reports

Development of correlation of gaseous ruthenium transfer rate to condensed water in accident of evaporation to dryness by boiling of reprocessed high level liquid waste in Fuel Reprocessing Facilities

Yoshida, Kazuo; Tamaki, Hitoshi; Yoshida, Naoki; Amano, Yuki; Abe, Hitoshi

JAEA-Research 2017-015, 18 Pages, 2018/01

JAEA-Research-2017-015.pdf:3.08MB

An accident of evaporation to dryness by boiling of high level liquid waste is postulated as one of the severe accidents at a fuel reprocessing facility. It was observed at the experiments that a large amount of ruthenium (Ru) is volatilized and transfer to the vapor phase in the tank. The nitric acid and water mixed vapor released from the tank is condensed. Volatilized Ru is expected to transfer into the condensed water at the compartments in the building. Quantitative estimation of the amount of Ru transferred condensed water is key issues to evaluate the reduction the amount of Ru through leak path in the facility building. This report presents that a correlation has been developed for Ru transfer rate to condensed water with vapor condensing rate based on the experimental results and additional thermal-hydraulic simulation of the experiments. Applicability of the correlation has been also demonstrated with the accident simulation of typical facilities in full-scale.

JAEA Reports

Development of analytical model for condensation of vapor mixture of nitric acid and water affected volatilized ruthenium behavior in accident of evaporation to dryness by boiling of reprocessed high level liquid waste at fuel reprocessing facilities

Yoshida, Kazuo

JAEA-Research 2016-012, 24 Pages, 2016/08

JAEA-Research-2016-012.pdf:3.04MB

An accident of evaporation to dryness by boiling of high level liquid waste is postulated as one of the severe accidents. In this case, Ru volatilization increases in liquid waste temperature over 120 centigrade at later boiling and dry out phases. It has been observed at the experiments with actual and synthetic liquid waste that some amount of Ru volatilizes and transfers into condensed nitric acid solution at those phases. The nitric acid and water vapor from waste tank condenses at compartments of actual facilities building. The volatilized Ru could transfer into condensed liquid. It is key issues for quantifying the amount of transferred Ru through the facility building to simulate these thermodynamic and chemical behaviors. An analytical model has been proposed in this report based on the condensation mechanisms of nitric acid and water in vapor-liquid equilibria. It has been also carried out to review the thermodynamic properties of nitric acid solution.

JAEA Reports

Accident analysis of evaporation to dryness by boiling of reprocessed high level liquid waste at fuel reprocessing facilities with considering severe accident measures

Yoshida, Kazuo

JAEA-Research 2016-004, 15 Pages, 2016/06

JAEA-Research-2016-004.pdf:2.22MB

An accident of evaporation to dryness by boiling of high level liquid waste is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, some amount of fission products (FPs) will be transferred to the vapor phase in the tank, and could be released to the environment. Two mitigative accident measures have been proposed by the licensee. One of them is injecting cold water to waste tanks to prevent dryness and another is leading generated vapor through temporary duct to huge spaces in the facility to condense to liquid. Thermal-hydraulics and aerosol transport behaviors in compartments of a typical facility building have been analyzed based on the scenario with these accident measures. The effects of measures are discussed form a view point of the reduction of radioactive material release to environment.

Journal Articles

Analysis of release and transport of aerial radioactive materials in accident of evaporation to dryness caused by boiling of reprocessed high-level liquid waste

Yoshida, Kazuo; Ishikawa, Jun; Abe, Hitoshi

Nihon Genshiryoku Gakkai Wabun Rombunshi, 14(4), p.213 - 226, 2015/12

An accident of evaporation to dryness by boiling of high level liquid waste (HLLW) is postulated as one of the severe accidents to occur caused by the loss of cooling function at a fuel reprocessing plant. In this case, some amount of fission products (FPs) will be transferred to the vapor phase in the tank, and could be released to the environment. Therefore, the quantitative estimation of transport and release behavior of FPs is one of the key issues in the assessment of the accident consequence. To resolve this issue, a systematic analysis method with computer codes has been developed based on the phenomenological behavior in boiling accident of HLLW. A simulation study demonstrated that the behaviors of liquid waste temperature and entrainment of mists were in good agreement with the experimental results during early boiling phase

Journal Articles

Experimental investigation of lead-bismuth evaporation behavior

Ohno, Shuji*; Miyahara, Shinya*; Kurata, Yuji

Journal of Nuclear Science and Technology, 42(7), p.593 - 599, 2005/07

no abstracts in English

Journal Articles

Evidence of complete fusion in the sub-barrier $$^{16}$$O+$$^{238}$$U reaction

Nishio, Katsuhisa; Ikezoe, Hiroshi; Nagame, Yuichiro; Asai, Masato; Tsukada, Kazuaki; Mitsuoka, Shinichi; Tsuruta, Kaoru; Sato, Kenichiro; Lin, C. J.; Osawa, Takaaki*

Physical Review Letters, 93(16), p.162701_1 - 162701_4, 2004/10

 Times Cited Count:79 Percentile:90.31(Physics, Multidisciplinary)

The fission fragment angular distributions for reactions using actinide targets such as $$^{16}$$O+$$^{238}$$U show anomalously large anisotropy than the prediction of the transition state model. To interprete this phenomenon, the orientation dependent quasi-fission model was proposed. As the $$^{238}$$U has prolate deformation, the interaction of $$^{16}$$O with the $$^{238}$$U in the sub-barrier region is restricted to the tip collisions. Hinde et al. interpreted that the anomalously large angular anisotropy is due to the quasi-fission, that is the complete fusion is not achieved in the sub-barrier region. The presence (or absence) of the complete fision is found by measuring the evaporation residue cross sections. We measured the evaporation residue cross sections for $$^{16}$$O+$$^{238}$$U by using the $$^{16}$$O beams supplied by the JAERI-tandem accelerator. As a result, complete fusion was observed in the sub-barrier region and no significant fusion hindrace was observed.

Journal Articles

Structure evolution and corresponding electrical properties in weakly bound Co-C60 mixture

Sakai, Seiji; Naramoto, Hiroshi; Xu, Y.; Priyanto, T. H.; Lavrentiev, V.; Narumi, Kazumasa

Materials Research Society Symposium Proceedings, Vol.788, p.L11.49.1 - L11.49.6, 2004/00

Mixture films between cobalt and C$$_{60}$$ (CoxC$$_{60}$$, x = 0.5-700) were prepared by co-evaporation technique under UHV conditions. The composition-dependent features of dilatation and downshift of Raman peak suggest that the mixtures are composed of cobalt particles and a C$$_{60}$$-based phase in which certain number of cobalt atoms are coordinated with C$$_{60}$$ molecules. It is deduced that the equilibrated number of cobalt atoms in the C$$_{60}$$-based phase is 4 atoms per C$$_{60}$$ molecule and in which an electron transfer occurs from a cobalt atom to a C$$_{60}$$ molecule. The evaluation of their temperature dependences reveals that: (1) The mixtures with x $$leq$$ 4 are thermally activated-type, and their conductive nature can be attributed to the C$$_{60}$$-based phase. Further (2) the mixtures between 4 $$<$$ x $$<$$ 60 are also thermally activated, however, the electron hopping process between the isolated cobalt particles is supposed to be operative (variable-range-hopping). And (3) in the mixtures with x $$geq$$ 60 which corresponds to a percolation threshold for cobalt particles, the system changes into metallic conduction.

Journal Articles

Experimental investigation of evaporation behavior for lead-bismuth eutectic and its impurity tellurium

Ohno, Shuji*; Miyahara, Shinya*; Kurata, Yuji

Proceedings of 12th International Conference on Nuclear Engineering (ICONE-12) (CD-ROM), 6 Pages, 2004/00

no abstracts in English

Journal Articles

Study on the stability of AmN and (Am,Zr)N

Takano, Masahide; Ito, Akinori; Akabori, Mitsuo; Minato, Kazuo; Numata, Masami

Proceedings of GLOBAL2003 Atoms for Prosperity; Updating Eisenhower's Global Vision for Nuclear Energy (CD-ROM), p.2285 - 2291, 2003/00

Stability of AmN and (Am,Zr)N was studied comparatively from the viewpoints of the hydrolytic and evaporative behavior. AmN powder reacted with moisture to form hydroxide Am(OH)$$_{3}$$, while the solid solution (Am$$_{0.1}$$Zr$$_{0.9}$$)N remained stable as long as 1000 hours. Stabilization effect of ZrN was found to depend significantly on its mole fraction from the experiments on (Dy,Zr)N. In the oxidation experiments on (Dy,Zr)N by TG-DTA technique, rapid weight gain by the oxidation occurred above 700 K. Effect of ZrN on the stability against oxygen was slight. Nitrogen release by the evaporation of AmN and (Am$$_{0.1}$$Zr$$_{0.9}$$)N in He gas flow was measured by gas chromatography. Evaporation rate constants of AmN were obtained at 1623-1733 K. Although the evaporation rate constant of AmN in the solid solution were lower than those of the pure AmN, the selective evaporation of AmN from the solid slution were recognized, which resulted in a decrease in the Am mole fraction.

Journal Articles

A One-dimensional dynamical soil-atmosphere tritiated water transport model

Yamazawa, Hiromi

Environmental Modelling & Software, 16(8), p.739 - 751, 2001/12

no abstracts in English

JAEA Reports

The GEM code: A simulation program for the evaporation and the fission process of an excited nucleus

Furihata, Shiori*; Niita, Koji*; Meigo, Shinichiro; Ikeda, Yujiro; Maekawa, Fujio

JAERI-Data/Code 2001-015, 90 Pages, 2001/03

JAERI-Data-Code-2001-015.pdf:3.75MB

no abstracts in English

Journal Articles

Deposition of HTO to water surface during a chronic HT release experiment

Noguchi, Hiroshi; Fukutani, Satoshi*; Yokoyama, Sumi; Kinouchi, Nobuyuki

KURRI-KR-61, p.18 - 25, 2000/00

no abstracts in English

Journal Articles

The Numerical simulation of melting and evaporation due to ultrashort pulse laser irradiation

*; Sasaki, Akira; Kunugi, Tomoaki*; *; *

Inst. Phys. Conf. Ser., (159), p.451 - 454, 1999/00

no abstracts in English

Journal Articles

Experimental study on fabrication technique of a Ni/Ti supermirror using the electron beam evaporation system

Soyama, Kazuhiko; ; *; Ebisawa, Toru*; Tasaki, Seiji*

Journal of Nuclear Science and Technology, 35(11), p.750 - 758, 1998/11

 Times Cited Count:5 Percentile:44.84(Nuclear Science & Technology)

no abstracts in English

Journal Articles

The Effect of the state of matter on the melting due to laser irradiation

*; Kunugi, Tomoaki*; *; *

Keisan Kogaku Koenkai Rombunshu, 3(1), p.235 - 238, 1998/05

no abstracts in English

JAEA Reports

An Upgraded version of the nucleon meson transport code: NMTC/JAERI97

Takada, Hiroshi; Yoshizawa, Nobuaki*; Kosako, Kazuaki*; *

JAERI-Data/Code 98-005, 101 Pages, 1998/02

JAERI-Data-Code-98-005.pdf:3.57MB

no abstracts in English

51 (Records 1-20 displayed on this page)