Lead Lithium Cooled Ceramic Breeder Research Articles

MHD effects of partition plates on thermofluid performance of Indian variant LLCB TBM for ITER

Abstract Liquid metal Lead-Lithium (PbLi) flow channels in Indian LLCB (lead lithium cooled ceramic breeder) Test Blanket Module consist of a sequence of parallel channels which are fed from a common inlet header. Thin radial-toroidal vertical plates known as partition plates at the central plane perpendicular to the applied magnetic field are primarily envisaged to enhance the mechanical strength of high aspect ratio electrically coupled parallel poloidal channels. In that case the partition plates are acting as an internal Hartmann wall and they have significant effects on velocity profile, pressure drop and heat transfer characteristics at ITER relevant applied magnetic field (B0 = 4 T). Three dimensional numerical simulation is performed in a model of full scale LLCB variant to study the effects of these partition plates on various flow field variables. Axial velocity near the thin partition wall and side wall jet structures are found to get significantly. Magneto-hydraulic pressure drop and redistribution of flow rates due to the presence of partition plates are assessed by comparing the results with no partition wall. Thermofluid simulation is carried out to obtain the temperature distribution of various structures for a given heat load profile based on neutronic estimation. The effects of buoyancy force on thermofluid flow profile in channels with high temperature gradient are also presented.

Thermofluid MHD studies in a model of Indian LLCB TBM at high magnetic field relevant to ITER

Numerical simulation of 3D MHD flow in a full scale variant of India propose Lead-Lithium cooled Ceramic Breeder (LLCB) Test Blanket Module(TBM) for ITER program has been carried out at high Hartmann number (Ha=17,845). The model geometry takes into account the integrated First wall (FW) which is provisioned with internal helium cooling channels for dual cooling purpose. The MHD effects on steady state velocity profile, modification of wall electric potential distribution due to electrical coupling of parallel channels has been analysed. Flow rate distribution in electrically coupled parallel channels has been obtained for a fixed PbLi flow rate in the common inlet header. Steady state thermofluid analysis has been performed using user defined heat density data obtained from neutronic estimation in similar variant. Prediction of thermal hot spots in various structural walls and sharing of heat load by coupled PbLi and First wall helium cooling circuit is presented.

Thermal-hydraulics and structural analyses of LLCB TBM set

Indian Lead-Lithium cooled Ceramic Breeder (LLCB) Test Blanket Module (TBM) is one of the tritium breeding Fusion blanket concepts. The paper discuses about the conceptual design and analysis work related to some of the key components of LLCB TBM set. First wall (FW) is a plasma facing component of the TBM designed to withstand high heat flux from plasma. FW is cooled by high pressure, high temperature helium gas flowing through coolant channels. The detailed thermal–hydraulics of FW has been performed based on the heat flux and neutronic heat generation. ANSYS CFX has been used for CFD analysis. The distribution of flow in different flow circuits of FW from manifolds has been performed and the flow distribution is found to be uniform in all the circuits. Thermal-hydraulic analysis of helium flow inside the FW channels and manifolds to estimate temperature, pressure drop and heat transfer coefficient has been discussed in the paper. TBM shield is located behind TBM to provide shielding from high energy neutrons to magnets and other components behind the TBM set. Water flows in parallel channels inside TBM Shield, provides the function of neutron moderator as well as coolant to remove heat deposited by the neutrons in the structure. Flow rate in parallel channels of shield has been regulated using orifice of different diameter. CFD Flow analysis inside shield has been performed to validate the distribution of flow inside the parallel channels. Based on velocities obtained, the heat transfer coefficient have been evaluated and thermal analysis of TBM shield has been performed considering thermal load from neutronic heat generation. The results obtained from thermal–hydraulic analysis of FW, manifolds and TBM shield have been used for thermo-structural analysis of LLCB TBM set based on load combinations as per ITER load specifications. RCC-MR 2007 code has been used for the structural assessment and prevention of p-type and s-type damages. The temperature and stresses are found to be within the acceptable limits and safety margins with some proposed modifications.

Design optimization of first wall and breeder unit module size for the Indian HCCB blanket module

The Indian test blanket module (TBM) program in ITER is one of the major steps in the Indian fusion reactor program for carrying out the R&D activities in the critical areas like design of tritium breeding blankets relevant to future Indian fusion devices (ITER relevant and DEMO). The Indian Lead–Lithium Cooled Ceramic Breeder (LLCB) blanket concept is one of the Indian DEMO relevant TBM, to be tested in ITER as a part of the TBM program. Helium-Cooled Ceramic Breeder (HCCB) is an alternative blanket concept that consists of lithium titanate (Li2TiO3) as ceramic breeder (CB) material in the form of packed pebble beds and beryllium as the neutron multiplier. Specifically, attentions are given to the optimization of first wall coolant channel design and size of breeder unit module considering coolant pressure and thermal loads for the proposed Indian HCCB blanket based on ITER relevant TBM and loading conditions. These analyses will help proceeding further in designing blankets for loads relevant to the future fusion device.

Helium cooling systems for Indian LLCB TBM testing in ITER

One of the key missions of ITER is to test and validate the various design concepts of tritium breeding blankets relevant to a power-producing reactor like DEMO. India is developing lead-lithium cooled ceramic breeder (LLCB) test blanket module (TBM) along with associated systems for testing in ITER. In LLCB TBM, Pb-Li eutectic alloy is used as multiplier, breeder, and coolant for the ceramic breeder (CB) zones, and lithium meta-titanate (Li2TiO3) the ceramic breeder is used as a tritium breeding material. The outer box structure is India-specific reduced activation ferritic martensitic steel (IN-RAFMS) and is cooled by high pressure, high temperature (8MPa, 300–500°C) helium gas named as first wall helium cooling system (FWHCS). The molten Pb-Li eutectic, flows separately around the lithium ceramic breeder pebble bed compartments to extract heat from the CBs. The Pb-Li system is cooled by separate helium system named as lead-lithium helium cooling system (LLHCS). This paper discusses the details of the process design, and process flow diagrams of the both the helium cooling systems, their operational states with reference to the ITER machine operational states, and performance & behavior of the helium systems during normal operation and accidental conditions.

Engineering design and analysis of Indian LLCB TBM set

India is developing Lead Lithium cooled Ceramic Breeder (LLCB) Test Blanket Module (TBM) for testing in ITER for the validation of fusion blanket design tools, tritium breeding performance and high grade heat extraction capability relevant to Indian DEMO. LLCB TBM is designed to withstand various ITER loads and its combinations, like thermal, mechanical including the high pressure coolant loads, electromagnetic loads during plasma disruption and seismic loading conditions. LLCB TBM system is designed in compliance with ITER Safety requirements and guidelines. A few challenging part in the design includes the design of helium cooled First Wall (FW) and back plates, the attachment system between TBM and the shield block to withstand loads for all the ITER operational modes, routing of high temperature process pipes between TBM and the shield block, interfaces between process pipes and the connecting flange, design of manifolds of different process fluids etc. Analysis has been performed on the LLCB TBM set using a Finite Element code, ANSYS. Relevant codes and standards, namely the French code RCC-MR, has been followed for the design analysis. The details of the analysis and further plans and proposals for improvement in design will be discussed in this paper.

Accident analyses of selected postulated events for safety assessment of Indian LLCB TBS in ITER

The Lead Lithium cooled Ceramic Breeder (LLCB) TBM) is being developed by India for testing in ITER machine. Thermal hydraulic safety analyses are the essential part of engineering design of LLCB Test Blanket System (TBS) for safe operation in ITER environment. The current work involves thermal hydraulic analyses and preliminary results of selected accident scenarios involving ancillary systems, the First Wall Helium Cooling System (FWHCS) and the Lead Lithium Cooling System (LLCS). A modified version of RELAP/MOD4.0 safety analysis code is used to simulate the transient scenarios. A detailed nodalization is carried out with all the major components in FWHCS and LLCS along with associated heat structures and connected confinement volumes. The accident analysis is performed for the scenarios including the ex-vessel Loss Of Coolant Accident (LOCA) in FWHCS into Port Interspace, Loss Of Fluid Accident (LOFA) and Loss Of Heat Sink (LOHS) accident in FWHCS and LLCS. Transient analyses results of each accident case are reported here and it is found that current design meets most of the thermal hydraulic safety requirements while changes in the design are proposed for certain accident scenarios.

Initial design and test of the tritium breeder monitoring system for the lead-lithium cooled ceramic breeder (LLCB) module of the ITER

The demonstration of a tritium breeder is an important part of an ITER mission. A concept for an experimental estimation of the tritium-breeding ratio (TBR) and the tritium-breeding dynamics in a test breeder module (TBM) of ITER has been developed. A system for the experimental estimation of the values is proposed for the lead–lithium cooled ceramic breeder (LLCB) TBM of ITER. The system is based on tritium breeder and neutron flux measurements under ITER plasma D-T experiments and the use of lithium carbonate sensors and neutron detectors. Three capsules with lithium carbonate (Li2CO3) containing different relative abundances of lithum-6 and lithium-7 (Li-6/Li-7 ratios of that found in nature: 1/1 and 9/1) and three capsules with neutron detectors are placed in a container. The low-level activities of the structural materials of the container and the capsules are used to prevent operation in a hot cell after the reactor irradiation of the container. For the delivery/withdrawal of the containers into/from the TBM, a pneumatic concept is suggested with a monitor channel connecting the TBM and an operating zone for conveying the containers in the TBM before the pulse and extracting them after the pulse. The initial design of the container with the capsules for the samples and the channel part in the TBM are presented in this paper. A laboratory facility for the investigation of the pneumatic parameters and the container moving in the channel is proposed. Neutron calculation is performed to estimate the tritium content in the lithium carbonate under reactor irradiation. The container model with the samples is proposed for testing on the nuclear reactor IVV-2M. The results of the tritium measurements in the lithium carbonate are discussed.

Liquid metal MHD experimental activities for LLCB TBM development

In Indian Lead Lithium cooled Ceramic Breeder (LLCB) blanket concept, Lead–Lithium (Pb–Li) liquid metal is used to extract heat from its own bulk volume and also from the neighboring solid breeder zones. The moderate flow velocity of Pb–Li inside the module can be significantly modified due to MHD effects, which arise because of the presence of strong toroidal magnetic field. Recently, two MHD experiments have been jointly carried out at Institute of Physics, University of Latvia (IPUL) with hot Pb–Li (∼350̊C) as the working fluid under a strong transverse magnetic field of up to ∼4.0T. The uncoated test sections are made of SS316L material and consist of LLCB TBM relevant flow geometries, such as rectangular and circular flow cross-sections, 90̊ bends, rectangular to circular flow transition region. The details of the liquid metal MHD experimental set up and experimental results are discussed in this paper.

Neutronic design of Indian LLCB TBM

India is developing lead lithium cooled ceramic breeder (LLCB) TBM to be tested in ITER. Liquid lead lithium along with lithium titanate has been adopted as basic material in Indian TBM for neutron multiplication and tritium breeding. RAFMS is used as the structural material and the first wall is cooled by helium. Li-6 enrichment is taken as 60 and 90% in lithium titanate and lead lithium, respectively. The LLCB TBM design is under progress and two design variants are being considered viz. plate design and tube design. In plate design the lead lithium and lithium titanate zones are arranged alternatively and are parallel to the first wall of TBM. In tube design circular tubes of RAFMS are assumed parallel to first wall and lead lithium flows inside the tubes or outside the tubes and lithium titanate is placed accordingly. For the neutronic design of the LLCB TBM, a detailed 3D neutronic model with “look alike” LLCB TBM in equatorial port in ITER has been constructed. A 3D neutron source has been used for the D-T neutrons emitted by plasma. Neutronic study is carried out using Monte Carlo transport code with FENDL-2.1 library with the following objectives: (1) to examine the profiles of heating and tritium production rates in the LLCB TBM, both in the radial and toroidal direction, in order to identify locations where neutronics measurements can be best performed with least perturbation from the surroundings, (2) to provide both local and integrated values for nuclear heating rates required for subsequent thermo-mechanical analysis, and (3) to compare the tritium production capabilities of two variants of the geometries. This paper will present the main findings from this neutronic study.

Analysis of the reference accidental sequence for safety assessment of LLCB TBM system

Abstract Safety analysis of the reference accidental sequence has been carried out for Lead Lithium cooled Ceramic Breeder (LLCB) Test Blanket Module (TBM) system; India's prototype of DEMO blanket concept for testing in International Thermonuclear Experimental Reactor (ITER). The accidental event analyzed starts with a Postulated Initiating Event (PIE) of ex-vessel loss of first wall helium coolant due to guillotine rupture of coolant pipe with simultaneous assumed failure of plasma shutdown system. Three different variants of the sequences analyzed include simultaneous additional failures of TBM and ITER first wall, failure of TBM box resulting in to spilling of lead lithium liquid metal in to vacuum vessel and reactor trip on Loss of Coolant Accident (LOCA) signal from TBM system. The analysis address specific reactor safety concerns, such as pressurization of confinement buildings, vacuum vessel pressurization, release of activated products and tritium during these accidental events and hydrogen production from chemical reactions between lead–lithium liquid metal and beryllium with water. An in-house customized computer code is developed and through these deterministic safety analyses the prescribed safety limits are shown to be well within limits for Indian LLCB-TBM design and it also meets overall safety goal for ITER. This paper reports transient analysis results of the safety assessment.

3D thermo-fluid MHD simulation of single straight channel flow in LLCB TBM

India is developing lead lithium cooled ceramic breeder (LLCB) blanket for its DEMO fusion reactor. The mock-up blanket (TBM), using this concept, will be tested in ITER for its tritium breeding and high-grade heat extraction efficiency. In this TBM, pressurized helium is used to remove the heat from first wall, top and bottom plates of TBM. The Pb–Li is used to extract heat from the breeder zones. The flow of Pb–Li with average velocity 0.1m/s inside the channel can be significantly modified due to MHD effects, which arise because of the presence of strong toroidal magnetic field. A numerical approach is established to capture this flow modification at higher Hartmann numbers (≥20,000). As a validation part of the developed code, MHD phenomenon is studied in 2-D square geometry and numerically obtained velocity profile is compared with available Hunt's analytical results. Thermo-fluid MHD analysis using this code, has been carried out for single rectangular duct of LLCB TBM. The heat transfer has been studied by keeping hot breeders at both sides of the flow channel. The results suggest modification in steady state MHD velocity profile as the liquid flows along the flow length. However, the temperature in various zone remains well within the maximum allowable limit.

Current status of design and engineering analysis of Indian LLCB TBM

One of the key missions of the international thermonuclear experimental reactor (ITER) is to test and validate the various design concepts of tritium breeding blankets relevant to a power-producing reactor like DEMO. India has developed two breeding blanket concepts such as, lead lithium cooled ceramic breeder (LLCB) and helium cooled ceramic breeder (HCCB) for its DEMO. LLCB concept will be tested in ITER where Li 2TiO 3 ceramic breeder (CB) in the form of packed pebble beds is used as a tritium breeding material and PbLi eutectic is used as multiplier, breeder, and coolant for the CB zones. A detail engineering design and analysis has been executed for the LLCB TBM to optimize the flow parameters for helium and PbLi circuits, to estimate the temperature distribution in the various breeding zones and to ensure the thermal design limits for structural material and temperature window in ceramic breeder for effective tritium extraction. The detailed thermo-hydraulic CFD using Fluent and FE simulation studies will also be discussed in this paper.