Experimental study on transport behavior of cesium iodide in the reactor coolant system under LWR severe accident conditions

Miyahara, Naoya; Miwa, Shuhei; Goullo, M.*; Imoto, Jumpei; Horiguchi, Naoki; Sato, Isamu*; Osaka, Masahiko

Journal of Nuclear Science and Technology, 57(12), p.1287 - 1296, 2020/12

https://doi.org/10.1080/00223131.2020.1782281

In order to clarify the cesium iodide (CsI) transport behavior with a focus on the mechanisms of gaseous iodine formation in the reactor coolant system of LWR under a severe accident condition, a reproductive experiment of CsI transport behavior was conducted using a facility equipped with a thermal gradient tube. Various analyses on deposits and airborne materials during transportation could elucidate two mechanisms for the gaseous iodine formation. One was the gaseous phase chemical reaction in Cs-I-O-H system at relatively high-temperature region, which led to gaseous iodine transport to the lower temperature region without any further changes in gas species due to the kinetics limitation effects. The other one was the chemical reactions related to condensed phase of CsI, namely those of CsI deposits on walls with surface of stainless steel to form CsCrO compound and CsI aerosol particles with steam, which were newly found in this study.

Unified description of the fission probability for highly excited nuclei

Iwamoto, Hiroki; Meigo, Shinichiro

Journal of Nuclear Science and Technology, 56(2), p.160 - 171, 2019/02

https://doi.org/10.1080/00223131.2018.1539351

We present a new model to describe the fission probability of the high-energy fission model, as deduced from the intranuclear cascade calculation with the Intra-Nuclear Cascade model of Lige (INCL) version 4.6 and Prokofiev's phenomenological systematics of the proton-induced fission cross sections. This model is implemented in the de-excitation model of the Generalized Evaporation Model (GEM), and applied to Monte Carlo spallation reaction simulation using the Particle and Heavy Ion Transport code System (PHITS). Comparing with experimental data for subactinide nuclei shows that this model can provide a unified prediction of the proton-, neutron-, and deuteron-induced fission cross sections with markedly improved accuracy. The calculated fission fragments tend to shift to higher mass numbers. To account for the isotopic distributions of fission fragments within the framework of a coupled INCL/GEM, modification of INCL is required, especially for description of the highly-excited states of residual nuclei.

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.

Corrections to the Nd method of evaluation of burnup for the PIE samples from Mihama-3 and Genkai-1 reactors

Suyama, Kenya; Mochizuki, Hiroki*

Annals of Nuclear Energy, 33(4), p.335 - 342, 2006/03

https://doi.org/10.1016/j.anucene.2005.11.009

The value of the burnup is one of the most important parameters of samples taken by post irradiation examination (PIE). In this study, concerning the PIE data from Mihama-3 and Genkai-1 PWRs, which were taken at the Japan Atomic Energy Research Institute, the burnup values of the PIE samples were re-evaluated and the PIE data are re-analyzed using SWAT and SWAT2 code systems with JENDL-3.3 library. This analysis concludes that the burnup values of samples from Mihama-3 and Genkai-1 PWRs should be corrected of 2-3%. The effect of re-evaluation of the burnup value on the neutron multiplication factor is approximately 1% for PIE samples having the burnup of larger than 30 GWd/t. Comparison between calculation results using a single pin cell model and an assembly model is carried out. Because the both results agreed within a few percents, we concluded that the single pin cell model is suitable for the analysis of PIE samples and the underestimation of plutonium isotopes does not result from the geometry model.

Simulation of chemical and electrochemical behavior of actinides and fission products in pyrochemical reprocessing

Minato, Kazuo; Hayashi, Hirokazu; Mizuguchi, Koji*; Sato, Takeyuki*; Amano, Osamu*; Miyamoto, Satoshi*

Proceedings of GLOBAL2003 Atoms for Prosperity; Updating Eisenhower's Global Vision for Nuclear Energy (CD-ROM), p.778 - 781, 2003/11

The simulation technology for the pyrochemical reprocessing of oxide fuels was developed to analyze experimental data, to predict experimental results, and to propose adequate conditions and processes. The simulation method was based on calculations of chemical equilibrium and electrochemical reactions. Some model calculations to simulate the experimental results were made on the process of electro-codeposition of UO and PuO. Although it was difficult to trace the experiments and compare the calculated results with the experimental results quantitatively due to the limitation of available data on the experimental conditions, the calculated results were consistent with the experimental results. The phenomena of the repeated oxidation-reduction reactions between Pu and Pu ions and those between Fe and Fe ions were theoretically analyzed,which caused the low current efficiency in the electro-codeposition process.

Calculation of fission reaction in the framework of QMD + SDM

Iwamoto, Osamu; Rong, J.; Fukahori, Tokio; Chiba, Satoshi

Journal of Nuclear Science and Technology, 39(Suppl.2), p.128 - 131, 2002/08

https://doi.org/10.1080/00223131.2002.10875057

The nucleon induced fission cross section and the fragment distribution are calculated using the Quantum Molecular Dynamics (QMD) plus Statistical Decay Model (SDM) in the nucleon energy range 10 MeV to 10 GeV. The fission cross section is calculated for Au, Bi and U and compared with experiments. The calculation predicts fairly well the experimental values. The mass and charge distribution is calculated for Pb and Th at 1.6-GeV and 190-MeV proton incident energy, respectively.

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

Systematic study of neutron induced reactions of the actinide nuclei

V.M.Maslov*;

JAERI-Research 96-030, 68 Pages, 1996/06

JAERI-Research-96-030.pdf:2.21MB

no abstracts in English

Measurements of thermal neutron capture cross sections and resonance integrals of long-lived fission product nuclei

Kato, Toshio*; Ogata, Yoshimune*; Harada, Hideo*; *; Sekine, Toshiaki;

Global 1995,Int. Conf. on Evaluation of Emerging Nuclear Fuel Cycle Systems, 2, p.1552 - 1559, 1995/00

no abstracts in English

Bulk shielding experiments on large SS316 assemblies bombarded by D-T neutrons, volume I; Experiment

Konno, Chikara; Maekawa, Fujio; Oyama, Yukio; Ikeda, Yujiro; Kosako, Kazuaki*; Maekawa, Hiroshi

JAERI-Research 94-043, 96 Pages, 1994/12

JAERI-Research-94-043.pdf:3.5MB

no abstracts in English