Experimental investigation on molten pool representing corium composition at Fukushima Daiichi nuclear power plant

An, Sang Mo; Song, Jin Ho; Kim, Jong-Yun; Kim, Hwan-Yeol; Naitoh, Masanori

doi:10.1016/j.jnucmat.2016.06.011

Cited by 21 publications

(8 citation statements)

References 11 publications

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“…Fischer et al [124] by repeating the same experiments with two BWR corium compositions (U/Zr = 0.83, same Cn, without and with 1.4 wt.% B4C) put in evidence in the post-test analyses, the zirconium diboride as the phase trapping boron. The presence of ZrB2 in the metallic phase was also reported in An et al [125] and Song et al [126]. From these observations, it can be expected that the effect of boron is to decrease the metallic zirconium amount previously available for the reduction of the UO2 and ZrO2 oxides since one part is chemically associated to boron to form zirconium diboride.…”

Section: High Temperature Regime (Above 2200 • C)supporting

confidence: 73%

Corium Experimental Thermodynamics: A Review and Some Perspectives

Barrachin

2021

Thermo

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More than 30 years ago a specialist meeting was held at Joint Research Center Ispra (Italy) from 15 to 17 January 1990 to review the current understanding of chemistry during severe accidents in light water reactors (LWR). Let us consider that, at the end of the 1980s, thermodynamics introduced in the severe accident codes was really poor. Only some equilibrium constants for a few simple reactions between stoichiometric compounds were used as well as some simple correlations giving estimates of solidus and liquidus temperatures. In the same time, the CALPHAD method was developed and was full of promise to approximate the thermodynamic properties of a complex thermochemical system by the way of a critical assessment of experimental data, a definition of a simple physical model and an optimisation procedure to define the values of the model parameters. It was evident that a nuclear thermodynamic database had to be developed with that new technique to obtain quite rapidly prominent progress in the knowledge of thermochemistry in the severe accident research area. Discussions focused on the important chemical phenomena that could occur across the wide range of conditions of a damaged nuclear plant. The most pressing need for improved chemical models is identified with condensed phase mixtures to model the corium progression. This paper reviews more than 30 years of experimental data production in the field of corium thermodynamics. This work has been conducted through multiple international programs (EURATOM, ISTC, OECD) as well as through more specific studies conducted at the national scale. This research has been capitalised in specific databases such as NUCLEA and TAF-ID, databases developed at IRSN and at CEA, respectively, and are now used in degradation models of the severe accident simulation codes. This research is presented in this paper. In the conclusion, we outline the research perspectives that need to be considered in order to address today’s and tomorrow’s issues.

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Section: High Temperature Regime (Above 2200 • C)supporting

confidence: 73%

Corium Experimental Thermodynamics: A Review and Some Perspectives

Barrachin

2021

Thermo

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“…Therefore, experimental programs considering the above issues were conducted after the 1F NPP accident in small scale experiments [18][19][20][21][22]. Ogura et al [18,19] conducted experiments using a high-speed thermocamera to explore the spreading and solidification behaviour, focusing on the relationship between the outlet diameters and the falling height under both dry/wet surface conditions. Furthermore, Yokoyama et al [23] examined the effect of the amount of molten metal and outlet diameters on the melt spreading behaviour.…”

Section: Unit 1 In 1f Nppsmentioning

confidence: 99%

Investigation of the Outflow and Spreading-Solidification Behaviour of Stratified Molten Metal

Yokoyama

Kondo

Suzuki

et al. 2021

JNE

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The spreading-solidification behaviour of the stratified molten metals was investigated. This is important in understanding the practical fuel debris distribution spread and solidified in the primary containment vessel (PCV) of Fukushima Daiichi Nuclear Power Plants (1F NPPs). In this study, the effect of outflow diameter on the material distribution before discharging was studied both experimentally and numerically. The two simulant metals were chosen so that the density ratio could be similar to the practical fuel and structure elements of the plant. They were arranged in a vessel and discharged on a receiving plate. The spreading experiments were performed using various outlet diameters with a density and reverse density stratification arrangement. After the experiment, X-ray analysis was performed to evaluate the material distribution in the solidified material. Moreover, a numerical analysis was performed to reveal the mechanisms that affect the material distribution after solidification. As a result, the low-density metal accumulated at the centre region regardless of the outlet diameters in the density stratification. In contrast, the outlet diameters affected the material distribution in the reverse density stratification because they affected the material outflow order. These findings may help increase our understanding of the fuel debris distribution in 1F NPPs.

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“…An et al [14] conducted a melting and solidification experiment in a cold crucible using an induction heating technique in order to investigate the composition of the molten core at the Fukushima Daiichi unit 1 [14]. This paper shows that fuel debris would be composed of two layers: an upper layer which is rich in metal (7.0 g.cm -3 ), containing a high amount of boron carbide (B4C, a neutron absorber); and a lower layer which is rich in oxide (7.9 g.cm -3 ), containing a low amount of B4C.…”

Section: Mcnp6 Model Of Fuel Debrismentioning

confidence: 99%

“…Weight percentages of each species were then calculated for each chemical element. The chemical composition of the MCNP6 model considering a uranium enrichment of 3 % is given in Table 1 In addition, the density of fuel debris -7 g.cm -3 -was taken from An et al [14]. The MCNP6 model of duel debris also includes S(α, β) thermal neutron scattering data (given for a temperature of 293.6 K) in order to avoid unsuitable free gas treatment at low neutron energies.…”

Section: Mcnp6 Model Of Fuel Debrismentioning

confidence: 99%