LHC Cryogenics - Strategy, unavailability root causes and limitations (RUN 2016)

Run2 (2016) is considered as very successful year. The cryogenic availability indicated by Cryo Maintain (CM) interlock reached the level of 98.6 %. Such a good result comes from multiple factors, where operation scenario is a strategic key point for the cryogenic production plants configuration. New operation scenario, with optimization on P18/P2 cryogenic plants, was validated and set as production configuration from 25 th March 2016. Helium yearly consumption was on the level of 14% of total inventory. Consolidations and repairs applied during YETS 2015 were effective and resulted directly in improvement of cryogenic stability and availability. Beam screen (BS) heat load was handled without particular problems thanks to optimized feed-forward logic and also by fact that beam parameters were limited by other factors than cryogenics. However, in some cases related heat load deposition was ~50% higher than values assumed for the LHC design. Last year operation period was affected with one major failure of a helium compressor. The system reconfiguration and applied strategy for the cryogenic spare parts allowed for continuous operation of the plant and replacement of defective part during dedicated technical stop.