Lead Lithium Ceramic Breeder Test Research Articles

Data-acquisition, control & interlock system design for corrosion experiments of IN-RAFM steel with flowing Pb-Li in presence of magnetic field

Indian Reduced Activation Ferritic Martensitic Steel (IN-RAFMS) has been selected as the reference structural material for Lead-Lithium Ceramic Breeder Test Blanket Module (LLCB TBM). Qualification requirements for the selected structural material include assessment of compatibility, in TBM-like conditions, against flowing eutectic lead-lithium (Pb-Li) liquid metal, which is primary coolant for TBM internal structures as well as a tritium breeder and neutron multiplier. In this view, corrosion experiments are planned to be conducted at relevant temperatures and flow conditions in a dedicated pump driven experimental loop fabricated at Institute for Plasma Research (IPR). Such an experimental facility requires continuous operation over long duration along with constant monitoring and control of critical process parameters like temperature, pressure and flow. In addition, to ensure occupational safety and investment protection of associated loop components, alarms and interlocks are required to notify any off-normal condition(s) arising during loop operation and to mitigate possible accidental scenarios. To perform the intended functions, a data-acquisition, control and interlock system is designed using PXI-express technology and LabVIEW software platform. Functionality of developed system has been successfully validated in an integrated manner. This paper discusses definitions and implementation methods of control and interlock logics. Detailed design of developed system including performance of pressure control system and electromagnet interlock module is presented.

Analysis of trace levels of impurities and hydrogen isotopes in helium purge gas using gas chromatography for tritium extraction system of an Indian lead lithium ceramic breeder test blanket module.

In the fusion fuel cycle, the accurate analysis and understanding of the chemical composition of any gas mixture is of great importance for the efficient design of a tritium extraction and purification system or any tritium handling system. Methods like laser Raman spectroscopy and gas chromatography with thermal conductivity detector have been considered for hydrogen isotopes analyses in fuel cycles. Gas chromatography with a cryogenic separation column has been used for the analysis of hydrogen isotopes gas mixtures in general due to its high reliability and ease of operation. Hydrogen isotopes gas mixture analysis with cryogenic columns has been reported earlier using different column materials for percentage level composition. In the present work, trace levels of hydrogen isotopes (∼100ppm of H2 and D2 ) have been analyzed with a Zeolite 5A and a modified γ-Al2 O3 column. Impurities in He gas (∼10ppm of H2 , O2 , and N2 ) have been analyzed using a Zeolite 13-X column. Gas chromatography with discharge ionization detection has been utilized for this purpose. The results of these experiments suggest that the columns developed were able to separate ppm levels of the desired components with a small response time (<6min) and good resolution in both cases.

Experimental measurement and numerical modeling of the effective thermal conductivity of lithium meta-titanate pebble bed

The effective thermal conductivity (keff) of lithium meta-titanate (Li2TiO3) pebble beds under fusion relevant environments is an important property for the design of IN LLCB TBM (Indian Lead Lithium Ceramic Breeder Test Blanket Module). The transient hot wire technique was used to examine the thermal property of the Indian made Li2TiO3 material. The hot wire is used as both the heating element as well as for the temperature measurement. The keff of Li2TiO3 pebble bed has been investigated from room temperature to 800 °C. Experiments were performed on uncompressed Li2TiO3 pebble bed in stagnant helium gas filled at ambient pressure. A clear dependence of the keff on the temperature of the pebble bed was observed. The pebble bed has pebbles of 1 ± 0.15 mm diameter and packing fraction of 63%. The experimental results showed that the keff increased from 0.903 W/m°C to 1.204 W/m°C with the increase of bed temperature from 34.3 °C to 785.4 °C. The random close packing of poly dispersed Li2TiO3 pebble bed has been generated using discrete element method and then numerical modeling has been performed using finite element method to estimate keff. The numerically determined keff of the Li2TiO3 pebble bed agrees reasonably well with the obtained experimental data. The experimentally achieved keff results are also compared with the reported experimental results elsewhere and also with Zehner–Schlunder correlation.

Status of India-specific Reduced Activation Ferritic-Martensitic steel and fabrication technologies development for LLCB TBM

India is developing the Lead Lithium Ceramic Breeder Test Blanket Module (LLCB TBM) for in-situ experiments in ITER. India-specific Reduced Activation Ferritic-Martensitic (IN-RAFM) steel is the chosen structural material for the fabrication of LLCB TBM. IN-RAFM steel plates with different thickness are being produced from commercial heats. Presently, characterization for mechanical and physical properties is in progress in order to generate material properties database from these commercial heats.In order to avoid welds on plasma facing surface of TBM First Wall (FW), scaled down mock-ups of FW are being fabricated using Hot Isostatic Pressing (HIP). Electron Beam (EB) welding, Laser/laser-hybrid welding and Narrow Gap-Tungsten Inert Gas (NG-TIG) welding, are being developed for fabrication of other TBM components. These welding processes have distinct advantage over conventional welding processes because of their high depth to width ratio, minimal HAZ, lower weld volume, reduced distortion and lower residual stresses in the weld joints. Mock-ups of LLCB TBM components are being fabricated using Grade 91/IN-RAFM steel to investigate the accessibility for the envisaged welding processes and to identify and develop the non-destructive evaluation (NDE) techniques. In addition, this would also help to establish the assembly sequence of LLCB TBM. Ultrasonic based methodologies are under development to assure integrity of these joints in the fabricated components.Details of these developments in IN-RAFM steel as structural material, fabrication technologies and mock-ups fabrication towards realization of the LLCB TBM are discussed in this paper.

Numerical modelling for the effective thermal conductivity of lithium meta titanate pebble bed with different packing structures

The effective thermal conductivity (keff) of lithium meta-titanate (Li2TiO3) pebble beds is an important parameter for the design and analysis of IN LLCB TBM (Indian Lead Lithium Ceramic Breeder Test Blanket Module). The keff of Li2TiO3 pebble beds under stagnant helium gas have been determined numerically using different uniform packing structures and random close packing (RCP) structures. The uniform packing structures of Li2TiO3 pebble bed are modelled by using the simple cubic, body centered cubic and face centered cubic arrangement. The packing structure of the RCP bed of Li2TiO3 pebbles is generated with the discrete element method (DEM) code. keff of Li2TiO3 pebble beds with different packing fractions have been reported as function of temperature; keff of the RCP Li2TiO3 pebble bed is compared with reported experimental results from literature. The numerically determined keff of the Li2TiO3 pebble bed agrees reasonably well with the experimental data.

Overview of LLCB TBM design and R&D activities in India

The Lead-Lithium Ceramic Breeder Test Blanket Module (LLCB-TBM) is the Indian TBM representing the DEMO breeding blanket, to be installed in ITER radial port no-2 for testing in ITER. The conceptual design of LLCB TBM systems and their engineering design are under progress. The neutronic analysis and engineering design of LLCB TBM set (TBM+TBM Shield) is undergoing optimization. The LLCB TBS auxiliary systems; Helium cooling systems, Lead-Lithium Cooling System and Tritium Extraction Systems design are conceptualized and detail design is under progress. The system arrangements in port cell area, Tokamak Cooling Water System (TCWS) vault and Tritium building along with interface requirements have been worked out within the allocated space. LLCB TBS related R&D activities are under progress at Institute for Plasma Research (IPR), Gandhinagar in association with Bhabha Atomic Research Centre (BARC), Mumbai and Indira Gandhi Centre for Atomic Research, Kalpakkam. The major research and development areas are liquidmetal technologies, lithium ceramic pebbles, lead-lithium eutectic alloy, India specific Reduced Activation Ferritic Martensitic Steels (IN-RAFMS) development and fabrication technologies development. This paper will highlight the current LLCB TBM set and axillary systems design and status of R&D activities in various areas.

Preliminary corrosion studies of P-91 in flowing lead–lithium with and without magnetic field for Indian lead–lithium ceramic breeder test blanket module

To study the corrosion of P-91 (9% chromium and 1% molybdenum) material with lead–lithium (Pb–Li) eutectic, two experiments were carried out in a forced convection loop, at eutectic temperature of 550 °C. The first experiment was carried out at a velocity of 15 cm s−1 for 1000 h and the second experiment, at a velocity of 30 cm s−1 for 2700 h. In both the experiments, P-91 sample coupons were exposed to Pb–Li flow in the presence and absence of magnetic field. Samples were analyzed using an optical microscope, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). Micro-Vickers hardness testing was also carried out. Dissolution of elements into liquid metal is the main corrosion mechanism. Iron and chromium were selectively getting leached out from the near-surface region (∼4 µm) in the first experiment and molybdenum and manganese were also found leaching from a greater depth in the second experiment. The samples kept in the magnetic field showed a higher corrosion rate (∼320 µm/year) as compared with the corrosion rate (∼200 µm/year) of the samples kept in non-magnetic field regions. Hardness of the exposed samples was lower than the unexposed samples in both the experiments. Hardness was found to be low in the near-surface region for all the samples in both the experiments.

Results of lead-lithium ceramic breeder TBM conceptual design optimization

Breeding zone optimization and choice of testing parameters in support of Indian conceptual design of lead-lithium ceramic breeder test blanket module for ITER are presented. Test matrix in ITER was estimated with regard to lead-lithium flow rate and inlet temperature variation. Direct and reversed lead-lithium flow modes are considered. Results of 1-D and 3-D thermal hydraulic analyses are compared.