Marigrazia Moscardini

• MS
• Research Associate at University of Pisa

The in-box LOCA (Loss of Coolant Accident) represents a major safety concern to be addressed in the design of the WCLL-BB (Water-Cooled Lead-Lithium Breeding Blanket) that will be tested in the Test Blanket Module of the ITER reactor. In this accident, a tube rupture in the coolant circuit would cause a potential disruptive exothermic chemical reac...

The European liquid Test Blanket Module (TBM) concept named Water Cooled Lithium Lead makes use of the liquid metal alloy PbLi as tritium breeder/neutron multiplier and water as coolant. A dedicated PbLi ancillary system feeds the detritiated liquid metal alloy to the TBM and returns the PbLi enriched with tritium. The object of this study is devel...

In the solid blanket concept, the tritium breeder and the neutron multiplier are both used in the form of pebble beds. Due to their discrete nature, the Discrete Element Analysis (DEM) allows determining the macroscopic behaviour of the bed as a result of the microscopic interactions among pebbles. At the Karlsruhe Institute of Technology, a Discre...

In the present paper, coupled STH/CFD calculations are performed addressing two operating conditions in the frame of the NACIE-UP experimental campaign. In order to simulate mixed and natural circulation phenomena related to liquid metals thermal hydraulics, the RELAP5/Mod3.3 STH code and the CFD code ANSYS Fluent are adopted in an integrated manne...

This work aims to review the general guidelines to be adopted to perform coupled System Thermal Hydraulics (STH)/CFD calculations. The coupled analysis is often required when complex phenomena characterized by different characteristic time and length scales are investigated. Indeed, by STH/CFD coupling the main drawbacks of both stand-alone codes a...

The present work deals with simulations carried out at the University of Pisa by using the System Thermal Hydraulics code RELAP5/Mod3.3 to support the experimental campaign conducted at the ENEA (Energia Nucleare ed Energie Alternative) Brasimone Research Centre on the CIRColazione Eutettico—Heavy liquid mEtal pRessurized water cOoled tubes (CIRCE-...

The paper presents the application of a coupling methodology between Computational Fluid Dynamics (CFD) and System Thermal Hydraulic (STH) codes developed at the University of Pisa. The methodology was applied to the CIRCE-HERO facility in order to reproduce the recently performed experimental conditions simulating a Protected Loss Of Flow Accident...

Lithium orthosilicate (Li4SiO4, LOS) based advanced ceramic pebbles are currently the reference material in Europe for solid tritium breeder blankets. These breeder pebbles, as the constituent of pebble beds, are not structural members but undergo cyclic thermo-mechanical compression. To withstand these operational loads, lithium metatitanate (Li2T...

An analytical model including the Smoluchowski effect to estimate the effective thermal conductivity of a monosized granular assembly with interstitial stagnant gas from the microstructural parameters of the assembly, as well as the bulk properties of the granules and the gas is proposed in this paper. The discrete element method (DEM) is used for...

The Effective thermal conductivity (keff) is one of the key thermal properties for packed beds in the presence of a stagnant fluid. In this study, a thermal discrete element model (DEM) based on the original Cheng-Yu-Zulli analytical model for mono-sized packed beds has been improved and implemented especially for mixed beds of different particle s...

In this work, an in-house thermal–Discrete Element Method (DEM) code, recently developed at Karlsruhe Institute of Technology to evaluate the heat transfer in ceramic packed pebble beds, was applied to study the thermal behavior of the breeder beds of the European solid breeder blanket concept. The breeder zone of the helium-cooled pebble bed (HCPB...

Uniaxial compression test (UCT) experiments were conducted along with Discrete Element Method (DEM) simulations. The objective was to investigate the effect of the material properties and of the blanket operational parameters (in terms of packing factor, pebble material/size, compressive load and bed height) on the mechanical response of breeder be...

In the framework of the EUROfusion’s Power Plant Physics and Technology, the Working Package Breeding Blanket aims at investigating 4 different Breeding Blanket (BB) concepts for a EU demonstration fusion reactor (DEMO). One of these concepts is the Helium Cooled Pebble Bed (HCPB) BB, which is based on the use of pebble beds of lithiated ternary co...

In this paper, a Discrete Element Method (DEM) for the evaluation of the effective thermal conductivity of pebble beds in fusion blankets is presented. Pebble beds are multiphase materials in which both the solid and the gas phase filling the voids between particles coexist. The effective thermal conductivity of a pebble bed depends on the thermal...

The breeder materials proposed for the solid tritium breeding blanket concepts are ceramic lithium-based compounds in the form of pebble beds. Different fabrication processes have been developed to produce pebbles with a high sphericity. However, a small deviation from a perfectly spherical shape exists. In this paper the influence of non-sphericit...

The determination of the thermal conductivity of breeder materials is one of the main goal in order to find the best candidate material for the fusion reactor technology. Experimental tests have been and will be carried out with a dedicated experimental devices, built at the Department of Civil and Industrial Engineering of the University of Pisa....

The experimental determination of mechanical and thermal properties of ceramic pebble beds, such as the lithium orthosilicate or lithium metatitanate, is a key issue in the framework of fusion power technology, for the reason that they are possible candidates in the design of breeder blankets. The paper deals with an experimental method for the eva...