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Abstract: The lead–lithium ceramic breeder (LLCB) TBM and its auxiliary systems are being developed by India for testing in ITER machine. The LLCB TBM consists of lithium titanate as ceramic breeder (CB) material in the form of packed pebble beds. The FW structural material is ferritic martensitic steel cooled by high-pressure helium gas and lead–lithium eutectic (Pb–Li) flowing separately around the ceramic breeder pebble bed to extract the nuclear heat from the CB zones. Low-pressure helium is purged inside the CB zone for in situ extraction of bred tritium. Currently the LLCB blanket design optimization is under progress. The performance of tritium breeding and high-grade heat extraction is being evaluated by neutronic analysis and thermal–hydraulic calculations for different LLCB cooling configurations and geometrical design variants. The LLCB TBM auxiliary systems such as, helium cooling system (HCS), lead–lithium cooling system (LLCS), tritium extraction system (TES) process design are under progress. Safety analysis of the LLCB test blanket system (TBS) is under progress for the contribution to preliminary safety report of ITER-TBMs. This paper will present the status of the LLCB TBM design, process integration design (PID) of the auxiliary systems and preliminary safety analysis results. [Copyright &y& Elsevier]

Abstract: In India, development of Lead–Lithium Ceramic Breeder (LLCB) blanket is being performed as the primary candidate of Test Blanket Module (TBM) towards DEMO reactor. The LLCB TBM will be tested from the first phase of ITER operation (H-H phase) in one-half of an ITER port no. 2. The Indian TBM R&D program is focused on the development of blanket materials and critical technologies: structural material (IN-RAFMS), breeding materials (Pb–Li, Li2TiO3), development of technologies for Lead–Lithium cooling system (LLCS), helium cooling system (HCS), tritium extraction system (TES) and TBM related fabrication technologies. This paper will provide an overview of LLCB TBM R&D activities under progress in India. [Copyright &y& Elsevier]

A novel plasma assisted tempering process has been developed to generate a stable α-Al 2 O 3 + FeAl coating on P91 steels. Hot dip aluminized P91 samples had been subjected to normalizing treatment in muffle furnace at 980 °C for 20 min followed by a glow discharge oxygen plasma assisted tempering treatment at 750 °C for 1 h. The plasma processing led to the formation of a stable α-Al 2 O 3 coating, while thermal tempering in muffle furnace led to formation of θ-Al 2 O 3 coating. Both the thermal and plasma tempered samples with alumina coating along with bare P91 samples were subjected to compatibility tests with Pb–17Li under static conditions at 550 °C for 1000 h. The extent of degradation of the samples was measured by weight loss method, X-ray diffraction and a cross-sectional examination with elemental studies using energy dispersive X-ray analysis. Plasma processed samples did not reveal any weight loss while thermally treated samples with metastable θ-Al 2 O 3 indicated 0.23 mg/cm 2 weight loss and bare P91 steels indicated a weight loss of 7.3 mg/cm 2 . [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Formation of delta(δ)-ferrite in the weld metal, during autogenous bead-on-plate welding of Reduced Activation Ferritic Martensitic (RAFM) steel using Gas Tungsten Arc Welding (GTAW) process, has been studied. Composition of the alloy is such that delta-ferrite is not expected in the alloy; but examination of the weld metal revealed presence of delta-ferrite in the weld metal. Volume fraction of delta-ferrite is found to be higher in the weld interface than in the rest of the fusion zone. Decrease in the volume fraction of delta-ferrite, with an increase in preheat temperature or with an increase in heat input, is observed. Results indicate that the cooling rate experienced during welding affects the volume fraction of delta-ferrite retained in the weld metal and variation in the delta-ferrite content with cooling rate is explained with variation in the time that the weld metal spends in various temperature regimes in which delta-ferrite is stable for the alloy during its cooling from the liquid metal to the ambient temperature. This manuscript will discuss the effect of welding parameters on formation of delta-ferrite and its retention in the weld metal of RAFM steel. [ABSTRACT FROM AUTHOR]

This paper presents a detailed electron microscopy study on the microstructure of various regions of weldment fabricated by three welding methods namely tungsten inert gas welding, electron beam welding and laser beam welding in an indigenously developed 9Cr reduced activation ferritic/martensitic steel. Electron back scatter diffraction studies showed a random micro-texture in all the three welds. Microstructural changes during thermal exposures were studied and corroborated with hardness and optimized conditions for the post weld heat treatment have been identified for this steel. Hollomon–Jaffe parameter has been used to estimate the extent of tempering. The activation energy for the tempering process has been evaluated and found to be corresponding to interstitial diffusion of carbon in ferrite matrix. The type and microchemistry of secondary phases in different regions of the weldment have been identified by analytical transmission electron microscopy. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study on the microstructural evolution in 9Cr reduced activation ferritic/martensitic steels during short term thermal exposures. Since the microstructure is strongly influenced by the alloying additions, mainly W, Ta and C contents, the effect of varying W and Ta contents on the martensite structure that forms during normalizing treatment and the subsequent changes during tempering of the martensite in the temperature regime of 923-1033 K have been studied. Microstructural changes like subgrain formation and nature of precipitates have been evaluated and correlated to hardness variations. The systematic change in size distribution and microchemistry of MC carbide is studied with variation in W content at different temperatures. [ABSTRACT FROM AUTHOR]

Abstract: Effects of tungsten and tantalum contents on impact, tensile, low cycle fatigue and creep properties of Reduced Activation Ferritic–Martensitic (RAFM) steel were studied to develop India-specific RAFM steel. Four heats of the steel have been melted with tungsten and tantalum contents in the ranges 1–2wt.% and 0.06–0.14wt.% respectively. Increase in tungsten content increased the ductile-to-brittle transition temperature (DBTT), low cycle fatigue and creep strength of the steel, whereas the tensile strength was not changed significantly. Increase in tantalum content increased the DBTT and low cycle fatigue strength of the steel whereas the tensile and creep strength decreased. Detailed TEM investigations revealed enhanced microstructural stability of the steel against creep exposure on tungsten addition. The RAFM steel having 1.4wt.% tungsten with 0.06wt.% tantalum was found to possess optimum combination of impact, tensile, low cycle fatigue and creep properties and is considered for Indian-specific RAFM steel. [Copyright &y& Elsevier]

Abstract: India has developed two concepts of breeding blanket for the DEMO reactor: one is Lead Lithium Ceramic Breeder (LLCB), and the other one is Helium-cooled Ceramic Breeder (HCCB) concept. Indian HCCB concept is having edge on configuration of helium-cooled solid breeder with RAFMS structure. Li2TiO3/Li4SiO4 and beryllium are used as the tritium breeder and neutron multiplier, respectively. 2D thermal–hydraulic simulation studies using ANSYS have been performed based on the heat load obtained from neutronics calculations to confirm heat removal under ITER pulsed operation. Transient thermal analysis has been simulated in ANSYS for the ITER relevant operational conditions. Thermal analysis provides important information about the temperature distribution in different materials used and their temperature–time histories. Result of thermal–hydraulic simulations shows that in each cycle, the maximum temperature of all materials remains same. The peak temperatures of all materials are well within their limiting value. Concept designs of HCCB blanket and its thermal hydraulic analysis will be presented in this paper. [Copyright &y& Elsevier]

Abstract: Hardness, tensile properties and microstructural changes in 9Cr–1W–0.06Ta–0.22V–0.08C Reduced Activation Ferritic–Martensitic steel have been investigated after subjecting the steel with isothermal heat treatments for 5min at temperatures in the range 973–1473K (below Ac1 to above Ac3 transformation temperatures) followed by oil quenching and tempering at 1033K for 1h. These studies have been carried out in an effort to assess the strength of the steel at different microstructural conditions. Optical, scanning and transmission electron microscopic investigations have been carried out to assess the microstructural changes of the steel upon various heat treatments. The steel developed predominantly tempered martensitic structure after the heat treatments. The hardness, tensile strength and the prior austenitic grain size of the steel exhibited minimum values for soaking heat treatment in the intercritical temperature range (i.e.) between Ac1 and Ac3; whereas the ductility was maximum. With increase in isothermal heat treatment temperature above Ac3, hardness, tensile strength and grain size of the steel were found to increase with consequent decrease in tensile ductility. TEM investigations revealed that the coarsening of subgrain and precipitates at grain and sub-grain boundaries on heat treatment of the steel in the inter-critical temperature range. The tensile properties of the steel have been correlated with microstructure. [Copyright &y& Elsevier]

Abstract: Effect of tungsten in the range of 1–2wt.% on tensile properties and flow behaviour of 9Cr–W–Ta–V Reduced Activation Ferritic–Martensitic (RAFM) steel has been investigated. The tungsten in the investigated range was found to have only minor effect on the tensile properties of the steel over the temperature range of 300–873K and at a strain rate of 3×10−3 s−1. The tensile flow behaviour of the RAFM steels was adequately described by the Voce’s constitutive equation. The tensile strength of the steels were predicted well from the parameters of the Voce’s constitutive equation. The Voce’s strain hardening parameter ‘n v’ was found to be quite sensitive to the tungsten content and predicted the onset of dislocation climbing process at relatively higher testing temperature with the increase in tungsten content. The equivalence between tensile and creep deformations and the influence of tungsten have been discussed. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]

Abstract: The objective of the ITER TBM Program is to provide the first experimental data on the performance of the breeding blankets in the integrated fusion nuclear environment. Such information is essential to design and predict the performance of DEMO and future fusion reactors. It foresees to test six mock-ups of breeding blankets, called Test Blanket Module (TBM), in three dedicated ITER equatorial ports from the beginning of the ITER operation. The TBM and its associated ancillary systems, including cooling system and tritium extraction system, forms the Test Blanket System (TBS) that will be fully integrated in the ITER machine and buildings. This paper describes the main features of the six TBSs that are presently planned for installation and operation in ITER, the main interfaces with other ITER systems and the main aspects of the TBM Program management. [Copyright &y& Elsevier]

Abstract: Tensile strength and flow behaviour of a Reduced Activation Ferritic–Martensitic (RAFM) steel (9Cr–1W–0.06Ta–0.22V–0.08C) have been investigated over a temperature range of 300–873K at different strain rates. Tensile strength of the steel decreased with temperature and increased with strain rate except at intermediate temperatures. Negative strain rate sensitivity of flow stress of the steel at intermediate temperatures revealed the occurrence of dynamic strain ageing in the steel, even though no serrated flow was observed. The tensile flow behaviour of the material was well represented by the Voce strain hardening equation for all the test conditions. Temperature and strain rate dependence of the various parameters of Voce equation were interpreted with the possible deformation mechanisms. The equivalence between the saturation stress at a given strain rate in tensile test and steady state deformation rate at a given stress in creep test was found to be satisfied by the RAFM steel. [Copyright &y& Elsevier]

Abstract: 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 Li2TiO3 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. [ABSTRACT FROM AUTHOR]

Abstract: In support of the ITER Test Blanket Module (TBM) program and coordinated by the Test Blanket Working Group, ITER party members have been focusing on the liquid metal blanket design concepts, most of which have been extensively explored. For the demonstration power reactor (DEMO) design, we will have to accommodate the neutron wall loading and first wall heat flux, breed and extract adequate tritium for the D-T fuel cycle and achieve high coolant outlet temperature for high power conversion efficiency. Most proposed liquid metal TBMs have the potential of achieving similar DEMO goals and requirements. Furthermore, all liquid metal TBMs are to satisfy ITER safety requirements and to be operated and tested within ITER operation scenarios. For the development of liquid metal TBM concepts, many R&D elements are common to a few designs such as the areas of Reduced Activation Ferritic/Martensitic Steel (RAFM, also abbreviated as FS in the following) or V-alloy fabrication, thermal fluid MHD, FS/PbLi, FS/Li and V-alloy/Li compatibility, irradiation effects on different materials, tritium extraction, SiC flow channel insert (FCI) development, etc. With a well-coordinated ITER TBM program, different parties’ R&D activities can supplement and complement each other via collaborations. This paper will present respective designs and R&D programs from seven ITER parties. [Copyright &y& Elsevier]