A scenario of core disruptive accident for Japan sodium-cooled fast reactor to achieve in-vessel retention

Suzuki, Tsuneo; Kamiyama, Kenji; Yamano, Hidemasa; Kubo, S.; Tobita, Yoshiharu; Nakai, Ryodai; Koyama, Kazuya

doi:10.1080/00223131.2013.877405

Cited by 91 publications

(27 citation statements)

References 12 publications

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“…The penetration distance of the melt was estimated to be as much 1 m, whereas the released diameters were 50 mm (T1) and 80 mm (T2). Suzuki et al (2014a) pointed out that the distance was much smaller than that predicted by the Saito correlation (Saito et al, 1988) [see Fig. 22 in Suzuki et al (2014a)].…”

Section: Introductionmentioning

confidence: 97%

“…The next generation of nuclear reactors is likely to include sodium-cooled fast reactors (SFRs), which are designed to shut down passively and non-energetically in the event of a core-disruptive accident (CDA) (Suzuki et al, 2014a). Even if the event is non-energetic, a considerable amount of the fuel may melt in the core region.…”

Section: Introductionmentioning

confidence: 99%

“…Suzuki et al (2014a) pointed out that the distance was much smaller than that predicted by the Saito correlation (Saito et al, 1988) [see Fig. 22 in Suzuki et al (2014a)]. Recently, Matsuba et al carried out experiments involving molten aluminum (Al) into sodium (Matsuba et al, 2016a) and molten alumina (Al2O3) into sodium (Matsuba et al, 2016b).…”

Section: Introductionmentioning

confidence: 99%

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Flow transition criteria of a liquid jet into a liquid pool

Saito

Abe

Koyama

2017

Nuclear Engineering and Design

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To better understand the fundamental interactions between melt jet and coolant during a coredisruptive accident at a sodium-cooled fast reactor, the jet breakup and droplet formation in immiscible liquid-liquid systems were studied experimentally. Experiments using two different pairs of test fluids were carried out at isothermal conditions. The observed jet breakup behavior was classified into characteristic regimes based on the classical Ohnesorge classification in liquid-gas systems. The variation in breakup length obtained in the present liquid-liquid system was similar to that in a liquidgas system. The droplet size distribution in each breakup regime was analyzed using image processing and droplet formation via pinch-off, satellite formation, and entrainment was observed. The measured droplet size was compared with those available from melt jet experiments. Based on the observation and analysis results, the breakup regimes were organized on a dimensionless operating diagram, with the derived correlations representing the criteria for regime boundaries of a liquid-liquid system. Finally, the experimental data were extrapolated to the expected conditions of a sodium-cooled fast reactor. From this, it was implied that most of the hydrodynamic conditions during an accident would be close to the atomization regime, in which entrainment is the dominant process for droplet formation. Nomenclature d droplet diameter Dj0 nozzle diameter

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Flow transition criteria of a liquid jet into a liquid pool

Saito

Abe

Koyama

2017

Nuclear Engineering and Design

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“…In order to secure the safety of sodium-cooled fast reactors (SFRs), it is important to achieve in-vessel retention (IVR) of the molten core material during postulated core disruptive accidents (CDAs). According to a probable scenario for CDAs [1], the molten core material would be discharged into the lower sodium plenum through the control rod guide tubes in the materialrelocation phase. Figure 1 shows a schematic of core material relocation during CDAs.…”

Section: Introductionmentioning

confidence: 99%

Distance for fragmentation of a simulated molten-core material discharged into a sodium pool

Matsuba

Isozaki

Kamiyama

et al. 2015

Journal of Nuclear Science and Technology

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A series of experiments has been carried out to obtain experimental knowledge on the distance for fragmentation of a molten core material discharged into the sodium plenum during postulated core disruptive accidents of sodium-cooled fast reactors. In the current experiments, 0.9 kg of molten aluminum (initial temperature: around 1473 K) was discharged into a sodium pool (diameter: 0.11 m, depth: 1 m, initial temperature: 673 K) through a nozzle (inner diameter: 20 mm). Visual observation of the fragmentation behavior was performed using an X-ray imaging system. The following experimental results were obtained. (1) Liquid column of molten aluminum was intensively fragmented almost simultaneously with a rapid expansion of sodium vapor in the vicinity of the column. (2) Due to the intensive fragmentation, penetration of the liquid column was limited to approximately 100 mm or so from the sodium level. (3) The molten aluminum was rapidly cooled after the intensive fragmentation. Based on these results, the distance for fragmentation of the liquid column was estimated to be 100 mm in the experiments. Through the current experiment, useful knowledge was obtained for the future development of an evaluation method of the distance for fragmentation of the molten core material.

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“…In a probable scenario for CDAs, it is considered that control rod guide tubes would become effective paths to discharge a large amount of molten core material into the lower sodium plenum of the reactor vessel (Suzuki et al, 2014). Although such discharge of core material would reduce the core reactivity substantially, it might also impose a significant thermal load on the lower structure in the reactor vessel, thus compromising the in-vessel retention (IVR) of molten core material.…”

Section: Introductionmentioning

confidence: 99%

Experimental discussion on fragmentation mechanism of molten oxide discharged into a sodium pool

Matsuba

Kamiyama

Toyooka

et al. 2016

Mechanical Engineering Journal

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In a probable scenario for core disruptive accidents of Sodium-cooled Fast Reactors (SFRs), it is foreseen that molten core material would be discharged into lower sodium plenums through control rod guide tubes. Such material relocation might lead to a considerable thermal load on lower structures of the reactor vessels, while it has been suggested that in SFRs, as soon as the molten core material is discharged into coolant, it might be fragmented into smaller particles by fuel-coolant interactions and thus efficiently cooled in the reactor vessels. Hence, understanding of the fragmentation is crucial for achieving in-vessel retention of molten core material in SFRs. In this paper, based on the experimental results of a series of fragmentation tests, where around 10 kg of molten alumina (Al 2 O 3 ) was discharged into a sodium pool (depth: 1.3 m, diameter: 0.4 m, temperature: 673 K) through a duct (inner diameter: 40mm to 63 mm) by using an experimental facility at National Nuclear Center of the Republic of Kazakhstan, dominant mechanisms for the fragmentation are discussed. In the present tests, mass median diameters of solidified Al 2 O 3 particles were around 0.3 mm, which were comparable to the values predicted using conventional hydrodynamic-instability theories. However, even though the conventional theories predict that particle size becomes smaller with the increase of Weber number, such tendency was not observed in the present tests. Taking into account that in the present tests, the distances for fragmentation of molten Al 2 O 3 were evaluated to be approximately 60 % to 70 % below the values predicted using an existing representative correlation which regards hydrodynamic instabilities as a dominant fragmentation mechanism, the observed independence on Weber number confirms a mechanism that before hydrodynamic instabilities sufficiently grow to induce fragmentation, thermal phenomena such as local coolant vaporization and resultant vapor expansion significantly accelerate fragmentation in SFRs.

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A scenario of core disruptive accident for Japan sodium-cooled fast reactor to achieve in-vessel retention

Cited by 91 publications

References 12 publications

Flow transition criteria of a liquid jet into a liquid pool

Flow transition criteria of a liquid jet into a liquid pool

Distance for fragmentation of a simulated molten-core material discharged into a sodium pool

Experimental discussion on fragmentation mechanism of molten oxide discharged into a sodium pool

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