Transcript Slides - Indico

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
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Analysis and limits
Preventive chemical treatment
Corrective chemical treatment
Annual preventive maintenance
Personnel protection
Conception and Follow up of Cooling Towers
• Conclusions
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%
Living Environment
Warm stagnant water
Installations with risks
Showers
Evaporative condensers
Whirlpool spas
Cooling towers
23 Cooling Towers at CERN
Power: 1.25 MW to 70 MW
Volume: 5 m3 to 4000 m3
LHC and SPS Cooling Towers
Cooling Tower
Cooling Towers at the Meyrin Site
Cooling Tower
French / Swiss Border
Analysis and Limits
Frequency now on a monthly basis
(In the past 2-4 times per year)
100 000 UFC/l
1 000 UFC/l
0 UFC/l
Stop disinfection,
Stop,
cleaning, purge
Corrective chemical
treatment
Preventive chemical
treatment
Preventive Chemical Treatment
• Continuous treatment
– Anti-scaling reduces
formation of bio-films
• Weekly treatment
– Biocide targeted on
general biocontamination (algae,
fungi, bacteria)
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
Annual Preventive Maintenance
• Disinfection of circuit
– Similar to corrective chemical treatment
• Purge of circuit
– not always practicable
– time consuming
• Mechanical cleaning
– Basins, structures, …
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
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
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%)
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
–…
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 : ?
Questions ?