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The SST-1 is a super conducting tokamak, which is in the final phase of assembly and commissioning. The super conducting magnet system of SST1 comprises of Toroidal field (TF) and Poloidal field (PF) coils. The 16 TF coils are nosed and clamped towards the in-board side and are supported toroidally with inter-coil structure at the out-board side, forming a rigid body system. The 9 PF coils are clamped on the TF coils structure. The integrated system of TF coils & PF coils forms the cold mass of @ 50 Ton weight. This cold mass is accommodated inside the cryostat and freely supported on the rigid support ring at 16 locations and support ring in-turn supported on 8 columns of machine support structure. During the operation this cold mass attains a cryogenic temperature of 4.2K in the hostile environment of high vacuum. The thermal excursion of cold mass and its supporting structure during this cool down results into severe frictional forces at the supporting surfaces. There is a design requirement of introducing a thin layer of solid lubricant film of MOS2 having coefficient of friction 0.05 between the sliding surfaces to control the stress contribution due to the friction.To ascertain the compatibility of molybdenum disulphide (MOS2) as a solid lubricant in high vacuum and very low temperature environment, we have carried out qualification tests on various samples and measured the coefficient of friction in both the room temperature conditions and at high vacuum & after thermal shocking to 4.2K temperatures. After successful qualification tests actual components are fabricated and integrated in the cold mass support structure assembly. This paper presents the design requirement, qualification tests performed and details about the integration of thin solid lubricant film of MOS2.

In the nuclear fusion reactor, ITER, the Loss of Coolant Accident (LOCA) in the Vacuum Vessel has to be managed with pressure suppression systems working at sub-atmospheric pressure. The operating conditions differ considerably from those experienced in the fission nuclear power plants such as BWR. The direct condensation at sub-atmospheric conditions is not sufficiently known, therefore, the effectiveness of systems operating at these particular conditions have to be investigated experimentally. A research program is being carried out at the University of Pisa, funded by ITER, in order to study the steam direct condensation for nuclear fusion reactor conditions. For this purpose, an experimental test facility was designed and built and an extended experimental program was performed. Video cameras were used to visualize the steam condensation at different mass flow rates. This paper deals with the elaboration of images of the steam jet flowing from a hole in the water. The steam condensation regimes depend on three governing parameters: downstream exit pressure, water temperature and steam mass flow rate per hole. Moreover, the condensation regimes are characterized by different shapes of steam jet. The image analysis permitted to determine the heat transfer coefficient in the stable condensation regime at sub-atmospheric conditions. The results obtained are compared with those correspondent at steam condensation at atmospheric pressure, emphasizing the great importance of the downstream exit pressure and the subcooling on the steam condensation.