Core Materials Inventory and Behavior

Akers, D.W.; McCardell, R.K.

doi:10.13182/nt89-a27649

Cited by 23 publications

(3 citation statements)

References 4 publications

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“…2) [93][94][95][96][97][98][99][100][101]. For instance, $45% of the fuel in the TMI-2 core was liquefied in the accident [102], while smaller amounts were observed in the integral tests including 15-18% in the four PBF SFD tests and 15% in the LOFT FP-2 test [42]. The Phebus FP tests, however, were more severe in which $ 20% of the fuel bundle was liquefied in FPT-1 and up to 50% in FPT-0 [20,21].…”

Section: Comparison Of Integral Experimentsmentioning

confidence: 99%

Overview of experimental programs on core melt progression and fission product release behaviour

Lewis

Dickson

Iglesias

et al. 2008

Journal of Nuclear Materials

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Section: Comparison Of Integral Experimentsmentioning

confidence: 99%

Overview of experimental programs on core melt progression and fission product release behaviour

Lewis

Dickson

Iglesias

et al. 2008

Journal of Nuclear Materials

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“…Such accidents have occurred in Chernobyl-1984, at the Three Mile Island unit-2 (TMI-2) in the USA-1979, and recently in Fukushima, Japan-2011 where 3 reactors were destroyed. The concept of debris bed formation was introduced by Akers and McCardell (1989) and McCardell et al (1990) upon the post-accident examination of the Three Mile Island unit-2 (TMI-2) that occured in the USA-1979. In the latter accident, the debris bed composed particle of sizes ranging over few millimeters (Akers et al (1986), Broughton et al (1989)) due to the relocation of molten materials inside the core upon quenching of the very hot rods being uncovered. In such situations different debris bed configurations might exist such as the formation of a debris bed surrounded by an intact zone of fuel rods or the existence of compact zones of very small particles limiting the coolant penetration.…”

Section: Introductionmentioning

confidence: 99%

Two phase flow redistribution in a two-layered porous medium with contrasting permeability

Swaidan

Fichot

Quintard

2017

Proceedings of CHT-17 ICHMT International Symposium on Advances in Computational Heat Transfer May 28-June 1, 2017, Napoli, Ita

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Motivated to investigate debris bed coolability in a damaged nuclear reactor core by bottom reflooding, this paper studies the physical situation involving injection of water into a superheated particle bed leading to high velocity flow of steam. The particle bed is composed of two cylindrical concentric parts and stratified vertically. One of the particular features of the studied configuration is that quenching of the superheated particles generates a strong flow of steam which may create a vertical pressure gradient leading the water in the lateral, more permeable medium, to flow faster than the injection velocity and consequently reducing the efficiency of cooling. The aim is to propose an analytical model to predict the behavior of water entrainment in the lateral layer (bypass) of larger permeability and porosity. This model computes the quench front velocity, water-to-steam conversion ratio, and the velocity of water in the bypass. It provides good qualitative and quantitative results for the two-phase flow redistribution as compared to experimental data. It also has several advantages as it allows: performing fast evaluations of the efficiency of cooling, upscaling to reactor-scale straightforwardly, and performing sensitivity studies on the physical properties of the particle beds and the fluid, and the variations of the momentum equations. For instance, it showed that the Generalized Darcy law was not sufficient to obtain acceptable evaluations whereas considering non-zero cross-terms in the Darcy Forchheimer equation by including an interfacial friction law succeeds in obtaining better results.

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“…Therefore, simulated fuel debris (SIMDEBRIS) samples having chemical composition and porosity similar to the TMI-2 debris were fabricated, and laboratory tests were performed to obtain the extensive data on thermal properties that are essential to accident analyses. Table 2 1ists an initial inventory of the core materials in TMI-2 [10] and the composition of SIMDEBRIS. In the preparation of SIMDEBRIS, the main elements of core materials were selected and it was assumed that all of them except silver were oxidized and uniformly mixed.…”

Section: Introductionmentioning

confidence: 99%

Thermal properties of Three Mile Island Unit 2 core debris and simulated debris

Nagase¹,

Uetsuka²

2012

Journal of Nuclear Science and Technology

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Thermal properties of molten and mixed core materials are required to be known for effective analysis of core damage in severe accidents at nuclear power plants. The specific heat capacity, thermal expansion coefficient, thermal diffusivity, and melting temperature were measured or estimated on the core debris samples of the Three Mile Island Unit 2 (TMI-2) reactor and simulated debris (SIMDEBRIS), which had chemical composition and porosity similar to the TMI-2 debris. The thermal diffusivity of the TMI-2 debris, which is mainly composed of (U, Zr)O 2 , is as low as 10-25% of UO 2 at room temperature but is comparable above 1500 K. The melting temperature of SIMDEBRIS is about 2840 K, which is equivalent to the liquidus temperature of (U, Zr)O 2 with the same ZrO 2 /UO 2 ratio. Accordingly, other core materials less than 10% in weight were observed to have no influence on the melting temperature.

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Core Materials Inventory and Behavior

Cited by 23 publications

References 4 publications

Overview of experimental programs on core melt progression and fission product release behaviour

Overview of experimental programs on core melt progression and fission product release behaviour

Two phase flow redistribution in a two-layered porous medium with contrasting permeability

Thermal properties of Three Mile Island Unit 2 core debris and simulated debris

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