Coolability of stratified UO/sub 2/ debris in sodium with downward heat removal: The D13 experiment

Ottinger, C.A.; Mitchell, G.W.; Reed, A.W.; Meister, H.

doi:10.2172/6519732

Cited by 3 publications

(2 citation statements)

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“…These phenomena will also lower the neutronic criticality of the debris bed by decreasing the thickness of debris bed. Although the existence of this phenomena was observed in the past in-pile experiment [18], mechanistic simulation tool has not been developed. In this study, two kinds of simulation tool were developed, namely macroscopic and microscopic models.…”

Section: The Development Of Simulation Tool Of Debris Bed Behaviormentioning

confidence: 99%

Development of the evaluation methodology for the material relocation behavior in the core disruptive accident of sodium-cooled fast reactors

Tobita

Kamiyama

Tagami

et al. 2016

Journal of Nuclear Science and Technology

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2016)Development of the evaluation methodology for the material relocation behavior in the core disruptive accident of sodium-cooled fast reactors, The in-vessel retention (IVR) of core disruptive accident (CDA) is of prime importance in enhancing safety characteristics of sodium-cooled fast reactors (SFRs). In the CDA of SFRs, molten core material relocates to the lower plenum of reactor vessel and may impose significant thermal load on the structures, resulting in the melt-through of the reactor vessel. In order to enable the assessment of this relocation process and prove that IVR of core material is the most probable consequence of the CDA in SFRs, a research program to develop the evaluation methodology for the material relocation behavior in the CDA of SFRs has been conducted. This program consists of three developmental studies, namely the development of the analysis method of molten material discharge from the core region, the development of evaluation methodology of molten material penetration into sodium pool, and the development of the simulation tool of debris bed behavior. The analysis method of molten material discharge was developed based on the computer code SIMMER-III since this code is designed to simulate the multi-phase, multi-component fluid dynamics with phase changes involved in the discharge process. Several experiments simulating the molten material discharge through duct using simulant materials were utilized as the basis of validation study of the physical models in this code. It was shown that SIMMER-III with improved physical models could simulate the molten material discharge behavior, including the momentum exchange with duct wall and thermal interaction with coolant. In order to develop an evaluation methodology of molten material penetration into sodium pool, a series of experiments simulating jet penetration behavior into sodium pool in SFR thermal condition were performed. These experiments revealed that the molten jet was fragmented in significantly shorter penetration length than the prediction by existing correlation for light water reactor conditions, due to the direct contact and thermal interaction of molten materials with coolant. The fragmented core materials form a sediment debris bed in the lower plenum. It is necessary to remove decay heat safely from this debris bed to achieve IVR. A simulation code to analyze the behavior of debris bed with decay heat was developed based on SIMMER-III code by implementing physical models, which simulate the interaction among solid particles in the bed. The code was validated by several experiments on the fluidization of particle bed by two-phase flow. These evaluation methodologies will serve as a basis for advanced safety assessment technology of SFRs in the future.

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Section: The Development Of Simulation Tool Of Debris Bed Behaviormentioning

confidence: 99%

Development of the evaluation methodology for the material relocation behavior in the core disruptive accident of sodium-cooled fast reactors

Tobita

Kamiyama

Tagami

et al. 2016

Journal of Nuclear Science and Technology

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“…The first experiments (D1 to D9) were insulated on the sides and bottom to allow us a one-dimensional heat transfer analysis with well-defined adiabatic boundary conditions. The latter experiments (D10 (22) and D13 (23) ) were bottom cooled to simulate cooling that might be provided by structures such as internal core catchers. Dry capsule experiments D8 and D12 investigated heat transfer in dry debris region including the melt of fuel and cladding, which simulated the dry zone in a sodium-cooled bed.…”

Section: Introductionmentioning

confidence: 99%

Experimental Analyses by SIMMER-III on Debris-Bed Coolability and Metallic Fuel Freezing Behavior

Yamano

Tobita

2011

JPES

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This paper describes experimental analyses using the SIMMER-III computer code, which is a two-dimensional multi-component multi-phase Eulerian fluid-dynamics code. Two topics of key phenomena in core disruptive accidents were presented in this paper: debris-bed coolability and metallic fuel freezing behavior. Related experimental database were reviewed to choose suitable experiments. To analyze the debris-bed coolability, the ACRR-D10 in-pile experiments were selected. SIMMER-III well simulated the heat transfer mechanisms including conduction, boiling and channeling observed in the experiment. Metallic fuel may freeze onto the stainless steel (cladding or wrapper tube) together with eutectic formation during core disruption in a metallic-fueled reactor. The CAFÉ-UT2 experiment carried out using pure UO 2 melt to investigate such phenomena was selected for the experimental analysis. In spite of no eutectic formation model in the SIMMER-III code, the calculated fuel penetration behavior was in good agreement with the experimental data.

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Study on Debris Bed Cooling Model for Sodium-Cooled Fast Reactor

Matsuo¹

2013

Trans.JSME, Ser.B

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This paper describes a debris-bed cooling model for a Sodium-Cooled Fast Reactor (SFR). The model aims at addressing not only the debris-bed consisted of the particles of the diameter with the hundreds of micrometers typically assumed with SFR but also the debris-bed with larger diameter particles. Then, it can cope with wider range of the scenario in the severe accident of SFR. Pressure losses of a laminar flow and a turbulent flow, gravity force and capillary force are considered in the basic equations. The present study model is validated through the analysis of the Sandia ACRR-D10 in-pile experiments utilizing real materials to simulate the SFR environment. Sensitivity analyses are performed by using the present study model to evaluate the influence of gravity force, turbulent flow pressure loss and the diameter of particles. It is shown from the sensitivity analysis, that gravity force influences the temperature and the liquid saturation in the debris-bed with larger diameter particles, while the turbulent flow pressure loss has small influence with the range of these sensitivity analyses.

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Coolability of stratified UO/sub 2/ debris in sodium with downward heat removal: The D13 experiment

Cited by 3 publications

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Development of the evaluation methodology for the material relocation behavior in the core disruptive accident of sodium-cooled fast reactors

Development of the evaluation methodology for the material relocation behavior in the core disruptive accident of sodium-cooled fast reactors

Experimental Analyses by SIMMER-III on Debris-Bed Coolability and Metallic Fuel Freezing Behavior

Study on Debris Bed Cooling Model for Sodium-Cooled Fast Reactor

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