Infrastructure maintenance

12 January 2009

The cooling and ventilation team of 2002, outside the towers (courtesy of Maximilien Brice)



Now that the detector’s open, there’s a lot of work to be done.  Aside from the repairs and refurbishments in the detectors, the services that keep ATLAS running also need attention. The service groups at CERN work on all the experiments, so our plans are linked in with the global maintenance schedule. As a result, the work is concentrated in February, between the ninth and 28th.

All possible maintenance activities – cooling, electrical, cryogenics, gas, and computer networks – are set for this period. The cooling and electrical work requires the detectors to be completely switched off, so these will be done simultaneously. During work on the cryogenics, gas, and computers, parts of the site can stay powered up.

The cooling system is most challenging. If it doesn’t run, nothing does – as we recently saw with the Wednesday morning power cuts in late November and early December. The evaporative cooling problems in the Inner Detector will also be addressed.

Apart from the existing problems, they’ll also complete some preemptive consolidation, removing “single point failures”. One such improvement is doubling the main pumps. “At this moment, if one of the main pumps fails, since there is only one, we stop,” according to Giuseppe Mornacchi of Operations Management.

The gas systems will also undergo the yearly routine maintenance, and the xenon system will see some additional work for its completion.

For all the special tasks, a major aspect of the maintenance is simply to dismantle and clean the machines and moving parts. CERN is legally bound to clean out the cooling towers annually so that legionella bacteria, which can cause very serious pneumonia, doesn’t get the chance to grow in the still water of the towers. That does not represent a danger to people though, as the system is a closed.

Also, the alarms and emergency stops will be tested. For one or two days, the CERN electrical systems group will push all the red buttons in ATLAS, “and check that when they push it, what is supposed to be cut is cut, and what is not supposed to be cut is not cut,” says Giuseppe.

As always, new machines will be added to the computing system. A few safety screens in the Control Room keep control and safety systems running while the computing system is down.

All in all, the winter maintenance should leave the services at Point 1 cleaner, more reliable, and more efficient. 

Katie McAlpine

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