The challenge of saving water

The word 'recycle' probably didn't mean a lot to you 26 years ago. That's when the SPS started working, along with its cooling circuits. Their mission was to cool the accelerators and detectors, keeping electronic circuitry and magnets at a constant temperature. But in 1976, we were less ecologically sensitive than today, so cooling water from Lac Léman was used only once in an open loop system. It travelled inside the SPS and then it was released back to the lake after being cooled by the cooling towers.
The Cooling and Ventilation group of ST Division has worked in recent years to create a closed loop in the SPS, 'in order to turn CERN into a more ecological centre with less waste of water', explains Mats Wilhelmsson, CV group leader and Mauro Nonis, the project leader for all the modifications in the water network at CERN. The original idea came from Alberto Scaramelli, the former group leader and present ST division leader. Thanks to this project, last year CERN only used 6.5 million cubic metres of water, 60% less than in 2000.
Timing was an important consideration since work could only take place in the six-month SPS shut down period of 2000 - 2001. The group worked in 65 different circuits and installations, and the air conditioning system for the tunnel and the surface buildings (BAs) also had to be changed. Moreover, the SPS team embarked on the project with some trepidation; the old system worked and as the old adage goes, 'if it ain't broke, don't fix it'. However, fix it they did, and after some tests on the magnets the SPS started reusing water in June last year, joining the PS which has been recycling since 1994. LEP also used to recycle water, and needless to say the LHC will also be a green machine!