49

CERN/ST-DI/ec (2002-111)

29 avril 2002

ST TECHNICAL COMMITTEE (STTC)

Compte rendu n° 49 de la réunion du 2/04/2002

Présents	:	J.L. Baldy, M. Bätz, G. Cumer, C. Colloca, A. Dagan, A. Funken, S. Grau, J. Inigo-Golfin, J. Lindroos, R. Nunes / ST D. Gueugnon / PS
Excusés ou absents	:	I. Bejar Alonso, C. Bertone, E. Cennini, P. Chevret, R. Charavay, P. Ciriani, K. Foraz, C. Jacot, J. Kuhnl-Kinel, R. Martini, P. Ninin, M. Nonis, J. Pedersen, B. Pirollet, R. Principe, I. Ruehl, E. Sanchez-Corral, A. Scaramelli, L. Scibile, T. Watson, M. Wilhelmsson/ST P. Collier / SL

1. Approbation du compte rendu précédent

Le compte rendu n° 48 est approuvé.

2. STOC Report (M. Bätz)

See attached document (ANNEX 1).

3. PS operation (D. Gueugnon)

Le "shutdown" PS est terminé, mais les machines n'ont pas encore redémarré. Nous sommes en période de tests. Il est prévu que le PSB délivre son premier faisceau le lundi 8 avril, et trois semaines plus tard, ce sera au tour du PS. Les machines avaient été fermées électriquement le lundi 25 mars, mais suite à un problème sur l'eau de refroidissement de l'aimant principal, l'anneau PS a du être à nouveau ouvert.
Suite à la dégradation de la membrane d'un clapet anti retour, des petits morceaux de caoutchouc se sont retrouvés dans le circuit d'eau de refroidissement de l'aimant. A titre de prévention, le circuit a été purgé, puis un remplissage a eu lieu. Chaque aimant est alors contrôlé. L'ensemble des tests devrait être terminé mercredi dans la journée et la fermeture de l'anneau PS pourrait alors avoir lieu en soirée ou jeudi matin 4 avril.

4. SPS operation (P. Collier)

P. Collier could not attend this meeting but has sent the following comments :

For the SPS, the shut-down is proceeding relatively smoothly - there is nothing special to report. Pre-closure of the machine is planned for 15 April, with the security patrol and full closure on the 25th April.

4. SNIFFER prototype results (S. Grau)

Silvia Grau presented the results of the SNIFFER prototypes, tested during the month of February 2002, with the companies OLDHAM, DEF, ICARE.

Below are the main conclusions of prototyping phase:

The combined detection of smoke, flammable gas and oxygen deficiency based on air sampling, is feasible.
Individual detectors technology meets the required response time.
Multiplexing technology does not meet the required response time. This technology is more complex than individual detectors and does not provide better performances.
Branching is feasible for the smoke detection. Around 5 branches per tube are possible, if higher response time is accepted. For this purpose, high sensitivity optical detectors or equivalent are required.
For safety reasons, branching is not recommended for the oxygen deficiency detection.
Perforations are not feasible for the dimensions of tubes specified by the Experiments (Ø ext <16 mm).
The detectors and pump/turbine associated to 10 air-sampling tubes fit in a 19" rack.
The presence of oxygen can be detected with the oxygen detectors used for the oxygen deficiency. About 1 % is the minimum presence of oxygen that can be detected.
The detection of CFC and inert gases is not feasible.
The measurement of humidity is not feasible.
Analogue values are available for flammable gas and oxygen deficiency detection.
Analogue values for the smoke detection are not available. Instead, several alarms levels exist.
With the development for a SNIFFER series production several parameters can be optimized, like the space in racks, response time and branching.

The transparencies of this presentation can be obtained by contacting Silvia Grau.

4. Replacement of the chilled water pipes in the PS tunnel (J. Lindroos)

See attached document (ANNEX 2).

5. Détection feu/gaz/évacuation surface, expériences & machines LHC (R. Nunès)

Voir ANNEXE 3.

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