The projects at the CERN research centre near Geneva require top performance and perfect cooperation among the physicists working here. In the same way as the researchers respond to challenges and pool their energies, security at the CERN site has also been resolved. Securiton began installing numerous security systems in the LEP project in 1985, as reported in the Securiton staff magazine “Sensor” in 1990.
For years, scientists at the European Organisation for Nuclear Research (CERN) near Geneva have been taking a deeper look into the basic structure of matter. Their tools are gigantic apparatuses, known as accelerators, which accelerate charged atomic particles almost at the speed of light before they collide with oncoming particles. The discovery of the W and Z bosons at CERN in 1983 is one of the great scientific achievements in high-energy physics. Carlo Rubbia and Simon Van der Meer, two of the approximately 200 scientists involved, received the Nobel Prize for their work. However, research continues inexorably. The goal is to try and uncover the mysteries of the origin of the universe and its laws.
The LEP project
1989 represented a milestone in the history of CERN’s construction: In mid-November, the massive LEP (Large Electron Positron Collider) was put into operation. This super-accelerator is an extremely complex system with several thousand precision elements and is the largest of its kind. Housed in a 27-kilometre ring tunnel, the LEP machine is located 50 to 150 metres below the earth’s surface. The tunnel measures 3.8 metres in diameter and passes through Swiss and French territory. The accelerator ring is the scene of revealing collisions: At almost the speed of light, electrons collide head-on with their counterparts made of antimatter – the so-called positrons. In doing so, they destroy each other and produce a multitude of new, even tinier particles. Four giant detectors are distributed around the LEP ring to capture, record and analyse these fragments of matter, one of which is called Aleph.
With its sophisticated equipment and computer systems, the LEP ring is an extremely expensive system (it costs around CHF 1.2 billion) and must be effectively protected against fire, among other risks.
Strict requirements
Following a rigorous selection process involving competitors at home and abroad, Securiton was commissioned with the installation of fire alarm systems in the LEP ring in December 1985, followed one year later by more systems in the 11 electronics facilities at the experiment hall UX 45 (Aleph detector). The prior evaluation showed that this tailor-made system best met the stringent requirements of the CERN engineers.
Contrafeu, a sister company of Securiton, was entrusted with supplying the extinguishing systems. The total order value for the two companies is around CHF 1.9 million.
Monitoring in the LEP ring
Fire monitoring includes the eight underground access stations, their immediate surroundings, the four experiment halls, parts of the main tunnel and the 16 caverns arranged around the LEP ring.
Monitoring in the experiment hall UX 45
The second major order relates to the UX 45 experiment hall, where the Aleph detector is located. The highly sensitive and complex computer system found in this huge detector measuring 12 x 12 x 12 metres evaluates the particle collisions. It is intended to provide physicists with information about the direction in which the atomic particles move, the timing of their passage and, in some cases, the identity of the particles. The fire protection equipment here includes a BMZ 3400 fire alarm control panel (floor-standing cabinet), 60 RAS 51 aspirating smoke detection systems (standard version), 76 optical smoke detectors and 10 stationary Halon 1301 extinguishing systems.
The FAS 3401 fire alarm system
This FAS 3401 automatic fire alarm system represents state-of-the-art technology and many years of experience. It includes a range of different automatic fire detectors (point and line-type detectors), manual call points, the fire alarm control panel and various alarm devices.
The software-controlled fire alarm control panel is the actual brains of the system. It monitors all functions and operating states, evaluates incoming signals and forwards them to the CERN information and management system via an interface.
In addition, all fire alarm control panels have emergency running characteristics. This ensures that, even in the event of a microprocessor failure, an alarm can be transmitted via direct line to the CERN plant fire brigade in Meyrin in the event of a fire.
220 RAS 53 aspirating smoke detection systems, which were specially developed for CERN’s requirements, are used in the LEP ring. This system has an analogue output for smoke measurement. A dedicated interface also enables the system and its remote control to be monitored at all times.
Design of the RAS aspirating smoke detection system
Essentially, this tried-and-tested system consists of two parts: the pipeline network with the small sampling points, and the detection chamber with built-in ventilator, scattered-light smoke detector and electronic monitoring circuit. Each suction line leads to its own detection chamber. This significantly increases the flexibility and safety of the overall system. Two LEDs on the map case indicate the alarm status of the detector or indicate a fault.
The ventilator ensures that air samples are continuously fed to the optical smoke detector via the pipeline network. In the event of a fire, it detects the smoke particles contained in the aspirated air. If the smoke concentration in the detector exceeds a certain level, the alarm is forwarded to the fire alarm control panel and the diode lights up on the detection chamber.
One advantage of this aspirating smoke detection system is its self-monitoring capabilities. The suction line is continuously monitored for leaks, pipe blockages and air flow rate, while the ventilator and smoke detector are also monitored for proper functioning. If a fault occurs, the second LED lights up automatically.
The RAS aspirating smoke detection system – one of Securiton’s specialities – has a range of possible uses and applications. For years, it has proven itself both in the protection of cultural property and in industry, for example in high-bay storage, IT rooms and aircraft hangars. This special fire alarm system is also used to monitor power plants and prisons. Even in deep-freeze rooms – where electronic devices often encounter problems – the special RAS 52 version meets the stringent requirements under extreme ambient conditions.
Effective firefighting
In the event of a fire, how are the expensive equipment and computer systems in the LEP ring and UX 45 experiment hall effectively protected? The 46 Halon 1301 extinguishing systems from Contrafeu guarantee direct and fast action against fire.
These extinguishing systems are actuated by the fire alarm system. Detectors – in this case the aspirating smoke detection systems – are switched in two-group dependency. If only one RAS system responds, a pre-alarm signal is issued as a warning. The extinguishing system is only activated when two fire detection systems trigger an alarm. Before this, the doors and fire dampers are automatically closed by the fire incident control on the fire alarm control panel.
In an emergency, the extinguishing agent flows out of the steel cylinders at high pressure within 10 seconds. The resulting concentration of extinguishing agent triggers a chemical reaction which directly intervenes in the combustion process and extinguishes the fire abruptly (inhibition).
The lines between the fire alarm control panel and the triggering element (solenoid valve) of the halon extinguishing system are monitored. An emergency power supply to the fire alarm control panel ensures unrestricted operation even in the event of a mains outage.
Maintenance
Servicing and maintenance are essential in ensuring the operational reliability of the many fire alarm systems. For this reason, multi-year maintenance contracts have been signed. Securiton service technicians ensure the full functionality of all fire alarm systems installed in the LEP and Aleph projects.