Alcator C-MOD Weekly Highlights June 19, 1995 Alcator C-MOD is presently in a scheduled maintenance and upgrade period. The operating campaign just completed lasted from November 17,1994 through June 9,1995, and included 27 run weeks, during which over 2300 successful plasma shots were produced. The present maintenance period will continue through the summer. Major planned activities include installation of a divertor Thomson scattering system, in collaboration with PPPL and PSI, and installation of a prototype divertor cryopump. Additional maintenance on internal and external hardware is also planned. Following completion of operation, the machine was allowed to warm up to room temperature. New density feedback electronics were installed and tested. A final calibration of the Thomson scattering system was performed, including Rayleigh scattering with the vessel back-filled in argon, and Raman scattering with hydrogen back-fill. A full leak check of all horizontal and vertical port Helicoflex (TM) seals was performed prior to breaking vacuum on Friday. The vessel was then brought up to air, and the large ports at G and C-ports removed to allow manned access. An inspection and survey was performed for the in-vessel hardware. In general, the internal components were found to be in good condition. The outboard divertor modules were in excellent shape, as were the outboard limiters. The ICRF antennas were also in very good condition.In addition to the two gusset protection tiles already known to have broken, four molybdenum tiles from inner divertor modules and one from an outer divertor module were found to have split and broken loose. There are a total of over 7000 molybdenum tiles in the divertor and first wall, and the loss of this small number had no detectable effect on operation. There were also some small misalignments of the lower inner divertor modules, presumably from disruption forces. These modules are being removed for further inspection and refurbishing. A list of alternator maintenance tasks to be carried out over the summer has also been developed, and these activities have begun.