HLMC Fuel Pin Bundle characterization in CIRCE-ICE pool facility

Abstract. This work, carried out at the DICI of Pisa University, in collaboration with ENEA Brasimone R.C., deals with the analysis and a preliminary discussion of the experimental tests performed in the Integral Circulation Experiment (ICE) configuration of the Circulation Eutectic (CIRCE) facility aiming to investigate the heat transfer in fuel rod bundle. The facility test section basically consists of an electrical bundle (FPS) made up of 37 pins arranged in a hexagonal wrapped lattice with a pitch to diameter ratio of 1.8. Along the FPS active length, two sections were instrumented to monitor the heat transfer coefficient along the bundle as well as the cladding temperatures at different ranks of the sub-channels. In particular, forced circulation condition tests were performed imposing a temperature difference through the FPS and a LBE mass flow rate through the FPS. Nusselt number in the sub-channels was calculated as function of the Peclet number and obtained results were compared to Nusselt numbers computed from correlations available in Heavy Liquid Metals (HLM) literature. Results shown that the Nu is slightly lower in the middle section (section 1) if compared with the ones into the upper section (section 3), and that behaviour is probably due to the turbulence of the flow which seems to be fully developed only in the upper part of the fuel pin bundle. Anyway the Nu number, calculated as function of the Pe number in the range Pe~1500÷3000 (forced circulation condition), matches well the numerical correlation available for HLM fuel pin bundle, (i.e. Ushakov and Mikityuk)

Heavy Liquid Metal Natural Circulation in a One -Dimensional Loop

ABSTRACT The ENEA Brasimone Research Centre since 1999 is strongly involved in the national and European research programmes performed in the field of heavy liquid metal technology aiming at the development of critical (LFR) and subcritical (ADS) nuclear systems. In particular, in the frame of the IP-EUROTRANS, (6th Framework Program EU), ENEA assumed the commitment to perform an integral experiment with the aim to reproduce the primary flow path of a HLM pool-type nuclear reactor, cooled by Lead Bismuth Eutectics (LBE). This new experimental activity, named ICE "Integral Circulation Experiment", will be performed by an appropriate test section designed to be installed in the CIRCE facility. In order to support the ICE activity, as well as characterise the natural and gas enhanced circulation flow regimes in a HLM loop, qualify test procedures, components nuclear relevant, a new facility was designed and built up by Brasimone Research Centre, named NACIE "NAtural CIrculation Experiment". The paper reports a detailed description of the loop and the main experimental results carried out from the natural circulation tests already performed on the NACIE loop. Numerical simulations have been performed in collaboration with the University of Pisa, adopting the RELAP5/Mod3.3 system code modified to allow for LBE as a cooling fluid. The aim of the performed post-test calculations is to compare the code response with the experimental results under the natural circulation flow regime, allowing to qualify the adopted nodalisation as well as the performance of the code when employed on HLM loop

Ti3SiC2 as a Candidate Material for Lead Cooled Fast Reactor

The aim of the present paper is to investigate the behaviour of the heavy liquid metal on the components of a circuit simulating lead cooled fast reactors

HLM Fuel Pin Bundle Characterization in CIRCE Pool Facility

Since the Lead-cooled Fast Reactor (LFR) has been conceptualized in the frame of GEN IV International Forum (GIF), ENEA is strongly involved on the HLM technology development. Currently ENEA has implemented large competencies and capabilities in the field of HLM thermal-hydraulic, coolant technology, material for high temperature applications, corrosion and material protection, heat transfer and removal, component development and testing, remote maintenance, procedure definition and coolant handling. In this frame the Integral Circulation Experiment (ICE) test section has been installed into the CIRCE pool facility, and suitable experiments have been carried out aiming to deeply investigate the pool thermal-hydraulic behavior of a HLM cooled pool reactor. In particular a fuel pin bundle simulator (FPS) has been installed in the CIRCE pool. It has been conceived with a thermal power of about 1 MW and a linear power up to 25kW/m, relevant values for a LMFR. It consist of 37 fuel pins (electrically simulated) placed on a hexagonal lattice with a pitch to diameter ratio of 1.8. The pins have a diameter of 8.2mm and active lengths of 1 m. Along the FPS, three spacer grid properly designed by ENEA have been installed. The FPS has been deeply instrumented by several thermocouples. In particular three sections of the FPS have been instrumented to monitor the heat transfer coefficient along the bundle as well as the cladding temperature in different rank of sub-channels. A full characterization of the FPS has been experimentally achieved both under forced and natural circulation, and the main results gained during the run are reported into the paper. Moreover the paper reports a preliminary analysis and discussion of such results, also in comparison with CFD calculations performed by CFX code

Natural and Gas Enhanced Circulation Tests in the NACIE Heavy Liquid Metal Loop

The paper reports on the results carried out from the natural circulation and gas-injection enhanced circulation tests performed on a heavy liquid metal loop, named NACIE, and located by the Brasimone ENEA Research Centre. The work is aimed at providing information on the characterization and interpretation of the basic mechanisms proposed in the design of future reactor relying on these circulation mechanisms. The results discussed in the present work concern the experiments performed using Lead Bismuth Eutectic (LBE) as coolant. Both natural circulation and gas-injection enhanced have been addressed, drawing conclusions about the observed phenomena. Numerical simulations have been performed in ollaboration with the University of Pisa, adopting the RELAP5/Mod3.3 system code modified to allow for LBE as a cooling fluid. Post-test calculations have been performed to compare the code response with the experimental results under the natural circulation and gas enhanced circulation flow regime, allowing to qualify the adopted nodalisation as well as the performance of the code when employed on HLM loop. The available data will allow to validate and qualify numerical tools for engineering application, establishing a reference experiment for the benchmark of commercial codes when employed in HLM loop

LBE-Water Interaction in LIFUS 5 Facility to Study a SGTR Event Under ELSY Reactor Conditions

In the framework of the research activities of the EURATOM FP6 project named ELSY (European Lead-cooled System), aimed at demonstrating the possibility of designing a competitive and safe fast critical reactor based on the Generation IV Lead Fast Reactor (LFR) concept, the study of the lead-water interaction following an incidental SGTR (Steam Generator Tube Rupture) event is an important issue to address. To simulate such event, an experimental test has been carried out on the LIFUS 5 facility at the ENEA Brasimone Research Centre, in order to assess the physical effects and the possible consequences connected to this kind of interaction. The experiment has been conducted by injecting water at the pressure of 185 bar and with a temperature of 300 °C into a volume of 80 l of Lead Bismuth Eutectic (LBE) kept at atmospheric pressure and at a temperature of 400 °C. The experimental facility has been suitably modified in order to reproduce as close as possible the operating conditions of the ELSY Steam Generator Unit (SGU), in which a free volume of cover gas (argon) is foreseen at the top of the system, with the objective to dampen the pressure waves inside the SGU itself. The experimental test has been supported through a numerical modelling campaign performed at the University of Pisa by means of the SIMMER code within both 2-D (SIMMER III) and 3-D (SIMMER IV) models. Pre-test simulations have been carried out to aid the design of the new facility configuration and to select the test conditions which could better reproduce the behaviour expected for ELSY. In addition, a post-test analysis has also been accomplished,allowing to compare the numerical and experimental results, so as to validate and assess the performance of the code when employed for this kind of applications

Heavy liquid metal natural circulation in a one-dimensional loop

The ENEA Brasimone Research Centre since 1999 is strongly involved in the national and European research programmes performed in the field of heavy liquid metal technology aiming at the development of critical (LFR) and subcritical (ADS) nuclear systems. In particular, in the frame of the IP-EUROTRANS, (6th Framework Program EU), ENEA assumed the commitment to perform an integral experiment with the aim to reproduce the primary flow path of a HLM pool-type nuclear reactor, cooled by lead bismuth eutectics (LBE). This new experimental activity, named ICE "Integral Circulation Experiment", will be performed by an appropriate test section designed to be installed in the CIRCE facility. In order to support the ICE activity, as well as characterize the natural and gas enhanced circulation flow regimes in a HLM loop, qualify test procedures and components which are nuclear relevant, a new facility was designed and built-up by Brasimone Research Centre, named NACIE "NAtural CIrculation Experiment". The paper reports a detailed description of the loop and the main experimental results carried out from the natural circulation tests already performed on the NACIE loop. Numerical simulations have been performed in collaboration with the University of Pisa, adopting the RELAP5/Mod3.3 system code modified to allow for LBE as a cooling fluid. The aim of the performed post-test calculations is to compare the code response with the experimental results under the natural circulation flow regime, allowing to qualify the adopted nodalization as well as the performance of the code when employed on HLM loop

Integral Circulation Experiment: Thermal–hydraulic simulator of a heavy liquid metal reactor

In the frame of the IP-EUROTRANS (6th Framework Program EU), domain DEMETRA, ENEA was involved in the Work Package 4.5 “Large Scale Integral Test”, devoted to characterize a relevant portion of a sub-critical ADS reactor block (core, internals, heat exchanger, cladding for fuel elements) in steady state, transient and accidental conditions. More in details ENEA assumed the commitment to perform an integral experiment aiming to reproduce the primary flow path of the “European Transmutation Demonstrator (ETD)” pool-type nuclear reactor, cooled by Lead Bismuth Eutectics (LBE). This experimental activity, called “Integral Circulation Experiment (ICE)”, has been implemented merging the efforts of several research institutes, among which, besides ENEA, FZK, CRS4 and University of Pisa, allowing to design an appropriate test section to be installed in the CIRCE facility. The goal of the experiments is therefore to demonstrate the technological feasibility of a heavy liquid metal (HLM) nuclear system pool-type in a relevant scale (1 MW), investigating the related thermal–hydraulic behaviour (heat source and heat exchanger coupling, primary system and downcomer coupling, gas trapping into the main stream, thermal stratification in the pool, forced and mixed convection in rod bundle) under both steady state and transient conditions. Moreover the preliminary as well as the planned experiments aims to address performance and reliability tests of some prototypical components, such as heat source, heat exchanger, chemistry control system. The paper reports a detailed description of the experiment, the design performed for the test section and its main components as well as the preliminary experimental results carried out in the first experimental campaign run on the CIRCE pool, which consists of a full power steady state test. The preliminary experimental results carried out have demonstrate the proper design of the test section trough the experiment goals as well as the HLM primary system technological viability. Moreover the results depicted into the paper are the first experimental data made available, especially for what concern the HLM pool thermal–hydraulic in a large scale system