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New Rules on Legionella Prevention

New Rules on Legionella Prevention. N. Bangert TS Workshop 2005, Archamps. Table of Contents. Diseases caused by Legionella Living environment / Installations with risk Cooling towers at CERN Analysis and limits Preventive chemical treatment Corrective chemical treatment

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New Rules on Legionella Prevention

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  1. New Rules on Legionella Prevention N. Bangert TS Workshop 2005, Archamps

  2. Table of Contents • Diseases caused by Legionella • Living environment / Installations with risk • Cooling towers at CERN • Analysis and limits • Preventive chemical treatment • Corrective chemical treatment • Annual preventive maintenance • Personnel protection • Conception and Follow up of Cooling Towers • Conclusions

  3. Diseases caused by Legionella = Legionellosis • Pontiac Fever • Flue-like illness (fever and muscle aches) • Incubation time: few hours to 3 days • Legionnaires’ Disease • Pneumonia (collapse of respiratory function) • Incubation time: up to 10 days • Mortality rate 5% to 30%

  4. Living Environment Warm stagnant water

  5. Installations with risks Showers Whirlpool spas Cooling towers Evaporative condensers

  6. Cooling Towers at CERN 23 Power: 1.25 MW to 70 MW Volume: 5 m3 to 4000 m3

  7. LHC and SPS Cooling Towers Cooling Tower

  8. Cooling Towers at the Meyrin Site Cooling Tower French / Swiss Border

  9. Analysis and Limits Frequency now on a monthly basis (In the past 2-4 times per year) Stop, disinfection, cleaning, purge Stop 100 000 UFC/l Corrective chemical treatment 1 000 UFC/l Preventive chemical treatment 0 UFC/l

  10. Preventive Chemical Treatment • Continuous treatment • Anti-scaling reduces formation of bio-films • Weekly treatment • Biocide targeted on general bio-contamination (algae, fungi, bacteria)

  11. Corrective Chemical Treatment • Amount of chemical depending on level of contamination and volume of circuit • Bio detergent detaches slime off the surfaces • Bactericide targets Legionella bacteria Slime Surface

  12. Annual Preventive Maintenance • Mechanical cleaning • Basins, structures, … • Disinfection of circuit • Similar to corrective chemical treatment • Purge of circuit • not always practicable • time consuming

  13. Personnel Protection • All personnel performing work in or close to cooling towers need to be properly trained regarding risks • Respiratory protective equipment need to be carried in case of exposure to aerosols or in cooling towers • Zones to be signaled

  14. Conception and Follow up of Cooling Towers • Free of dead end pipes • Drop separators installed • Good quality of supply water (Problems: SPS, STP18) • Accessibility for inspection and cleaning given • Technical documentation up to date • Installation logbook put in place • Follow up of water consumption and purges Methodical Risk Analysis

  15. Conclusion I: In Place • Respect of frequencies and type of analyses (100%) • Preventive and corrective chemical treatment defined (and applied if necessary) (100%) • Annual preventive maintenance (70%) • Completion and review of existing procedures about preventive and corrective activities (60%)

  16. Conclusion II: To-Do-List • Carry out a methodical risk analysis on all cooling tower circuits • Put warning signs in place • Implementation of a cooling tower Logbook • Training of personnel intervening on and operating the cooling towers • Update of hydraulic plans • …

  17. Conclusion III: Evaluation • Hydraulic disconnection of north area cooling towers to SPS ring • Hydraulic disconnection of STP18 from SPS • Put purge counters in place Budget evaluation / Schedule : ?

  18. Questions ?

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