Improvement of the resuspension model for OSCAAR using the atmosphere-soil-vegetation model SOLVEG-R (Contract research)

Nakanishi, Chika*; Ota, Masakazu; Hirouchi, Jun; Takahara, Shogo

JAEA-Research 2023-012, 29 Pages, 2024/02

JAEA-Research-2023-012.pdf:6.05MB

The OSCAAR program is a probabilistic risk assessment program for reactor accidents developed by Japan Atomic Energy Agency. To improve the model included in the OSCAAR program, which is about long-term exposure caused by the resuspension of radioactive materials deposited on soil surfaces, we calculated resuspension factors for Cs-137. The one- dimensional atmosphere-SOiL-VEGetation model, SOLVEG-R was utilized to compute resuspension factor. The wind velocity was kept constant in this study since it significantly affects particle resuspension behavior. Our calculations indicate that wind velocities below 6 m s resulted in little variation in the annual mean resuspension factor at a height of 1 m. However, as wind velocities increased above 6 m s, the resuspension factor significantly increased. The resuspension factors ranged from 10 to 10 m for wind velocities ranging from 1 m s to 7 m s.

The Dependence of pool scrubbing decontamination factor on particle number density; Modeling based on bubble mass and energy balances

Sun, Haomin; Shibamoto, Yasuteru; Hirose, Yoshiyasu; Kukita, Yutaka

Journal of Nuclear Science and Technology, 58(9), p.1048 - 1057, 2021/09

https://doi.org/10.1080/00223131.2021.1907254

no abstracts in English

Experimental investigation on fiber-coupled Raman spectrometry in presence of aerosols; Application for reactor containment gas detection in severe accident conditions

Sun, Haomin; Porcheron, E.*; Magne, S.*; Leroy, M.*; Dhote, J.*; Ruffien Ciszak, A.*; Bentaib, A.*

Proceedings of OECD/NEA Specialist Workshop on Advanced Measurement Method and Instrumentation for enhancing Severe Accident Management in an NPP addressing Emergency, Stabilization and Long-term Recovery Phases (SAMMI 2020) (Internet), 10 Pages, 2020/12

Experimental research on pool scrubbing of particles of radioactive materials

Akiba, Miyuki*; Hotta, Akitoshi*; Abe, Yutaka*; Sun, Haomin

Nihon Genshiryoku Gakkai Wabun Rombunshi, 19(1), p.1 - 15, 2020/02

https://doi.org/10.3327/taesj.J18.042

Tests at three different scales were conducted in order to understand the mechanisms of pool scrubbing. In the small-scale separate effect test, high resolution two-phase flow measurement techniques such as a high-speed camera, wire mesh sensor and PIV were applied to capture the behaviors of a single bubble and two-phase flow structures. In the large-scale integral effect test, the dependence of the aerosol removal efficiency on submergence and pool temperature was measured under constant pressure and depressurized conditions. To clarify relationships between individual phenomena and combined phenomena observed in two tests, the mid-scale integral effect test was undertaken.

Experimental investigation on dependence of decontamination factor on aerosol number concentration in pool scrubbing under normal temperature and pressure

Sun, Haomin; Machida, Shinichi*; Shibamoto, Yasuteru; Okagaki, Yuria; Yonomoto, Taisuke

Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 7 Pages, 2018/07

Observation of aerosol behavior near droplet interface

Uesawa, Shinichiro; Yoshida, Hiroyuki

Konsoryu, 32(1), p.140 - 149, 2018/03

no abstracts in English

Development of error reduction methods in aerosol measurement for pool scrubbing experiment

Sun, Haomin; Shibamoto, Yasuteru; Okagaki, Yuria; Yonomoto, Taisuke

Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 8 Pages, 2016/06

https://doi.org/10.1115/ICONE24-60359

Radionuclide transport behavior

Hidaka, Akihide

Enerugi Rebyu, 35(9), p.20 - 24, 2015/09

http://ci.nii.ac.jp/naid/40020565747

Operation of nuclear power plant causes accumulation of radionuclides in fuel rods as a result of nuclear fission of uranium and plutonium. During severe accidents, large amount of radionuclides are released from fuel and transport in the reactor coolant system and/or the containment. When the containment fails or its confinement function is lost, radionuclides could be released into the environment. Meanwhile, radionuclides can be removed by condensation onto wall, natural deposition such as gravitational settling, the engineered safety features (ESF) such as containment spray and so on. After various processes described above, the species, amounts and timing of radionuclide released into the environment is called source terms. The behavior of radionuclide can be described mechanistically by condensation or evaporation of gaseous radionuclide, deposition, growth and removal of aerosol by ESF. Present paper summarizes the radionuclide behavior during severe accidents.

Remote particle counter for clean rooms

Ozu, Akira; Okamoto, Ryuta*; Kawakita, Hiroshi*

Kurin Tekunoroji, 16(3), p.56 - 61, 2006/03

In recent years, particle counting devices capable of monitoring particles suspended in air on real-time basis are of considerable practical concern in the fields of semiconductor and large display panel industries. A remote particle counter, which had been developed for monitoring aerosols released in air from nuclear facilities, has been applied to a measurement system for clean rooms used in the fields. It can visualize the particles in narrow space at a distance of 6m and derive the number and size distribution of particles with diameter of above 0.5 microns. By improving the laser energy, sensitivity of the image intensifier camera, and magnification of the zoom lens used in the system, it is possible to detect the particles with diameters of below 0.5 microns. The method and the current performance of the measurement system are described.

Analyses of radio-nuclides release and transport in VEGA-1 and -3 tests with VICTORIA2.0 code

Hidaka, Akihide*; Kudo, Tamotsu; Kida, Mitsuko; Fuketa, Toyoshi

JAERI-Research 2005-001, 67 Pages, 2005/02

JAERI-Research-2005-001.pdf:3.38MB

In the VEGA program to investigate radionuclides release from irradiated fuel during severe accidents, the analyses are being performed with VICTORIA2.0 code for comprehensive understanding of radionuclides release and transport phenomena. The VEGA-1 and -3 tests were analyzed in the present study. The correlation for Cs diffusion coefficient in fuel grain obtained from VEGA-1 was applied to the release analysis of VEGA-3. The calculated release of Cs agreed well with the measurement. The correlation was applied to subsequent Cs transport and deposition analyses. The calculation underpredicted the total mass of Cs deposited onto the test apparatuses because nucleation of aerosol and its growth were underestimated due to the consideration of aerosol nucleation originated only from released FP in VICTORIA2.0. A sensitivity analysis with aerosol seeds for heterogeneous nucleation showed a reasonable agreement with the measured Cs distribution. It turned out that additional aerosol seeds besides the released FP be considered when the VICTORIA2.0 code is applied to the VEGA test analyses.