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Integrity of tempered martensitic grade 92 (9Cr-1.8W-0.5Mo-VNb) steel welded joint has been assessed by carrying out creep test at 923 K over a wide stress range. The failure location in the joint was found to shift from base metal to heat affected zone (HAZ) of the weld joint with decrease in applied stress. The HAZ of the weld joint consisted of coarse prior-austenite grain (CGHAZ), fine prior-austenite grain (FGHAZ) and intercritical (ICHAZ) regions in a sequence from the fusion boundary to unaffected base metal. The failure was associated with localized creep deformation coupled with creep cavitation. To have a better insight to the creep failure behaviour of the joint, the different microstructural constituents of HAZ of the joint has been simulated. Creep and tensile tests were carried out on the simulated HAZs specimens. The steel suffered degradation in creep rupture strength on subjecting heating in the intercritical (between Ac 1 and Ac 3 ) (ICHAZ) as well as at temperature just above the Ac 3 (FCHAZ). The extensive creep cavitation has been observed in the simulated FGHAZ of the joint. Similarly, localized extensive creep cavitation and precipitation of tungsten rich Laves phase has been observed in the FGHAZ of the weld joint. This caused the type IV failure in the FGHAZ of the weld joint. The integrity of grade 92 steel joint under creep condition is governed by the above microstructural modifications of the steel in HAZ by weld thermal cycle.

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As a part of the development and testing of a lead lithium eutectic (Pb-16Li) purification system at IPR, a wire mesh packing based prototype cold trap (CT) was designed, fabricated and installed in a purification loop to remove the impurities from ∼ 260 kg of the Pb-16Li. In the present work, the functionality of CT has been assessed continuously for a long duration of ∼3500 hour (∼5 months), in the molten Pb-16Li system. This long-duration operation of CT in the Pb-16Li system was imperative to test its reliability, since the recurrent replacement of the CT in the Pb-16Li system may not be feasible due to stringent operating conditions of fusion reactors. During the present experiment, the working of an impurity generator has been tested and the deposition of corrosion impurities has been achieved on the wire mesh packing of CT. The efficiency of CT has been estimated to assess the performance of the CT. Some oxide depositions were also found inside the CT. Different characterization techniques such as SEM-EDX, XRD, and ICP-AES were used for the characterization of the samples taken from the CT. The characterization results of needle shape deposition suggest the formation of iron–nickel intermetallic while the characterization of oxide deposition suggests the formation of Pb2O, Li2O, and PbO.