Speaker
Description
Summary
The KM3NeT consortium, including members of the ANTARES, NEMO and NESTOR collaborations, is developing a kilometre cube-scale neutrino telescope for the Mediterranean sea.
The construction of such a detector will require the solution of technological problems common to many deep submarine installations.
Several hundred vertical detection units containing photomultipliers will be deployed on a seafloor site up to 100 km far from the shore below several kilometres the sea level.
The power system is composed of an AC/DC shore power feeding station, a management and control system, a standard, single conductor 10 kV DC rated electro-optical telecommunications cable with sea-water current return and a distribution network to deliver power to the neutrino telescope. On the seabed specially-developed DC/DC converters will reduce the transmission voltage to 400 V for distribution to the detection units.
The sea-floor network will consist of several junction boxes linked by electro-optical cables to the telescope detection units and satellite ocean sciences nodes. The final design of the network is still under development and will incorporate extensive redundancy to mitigate single point failures.
The design requirements for an ocean observatory site-to-shore cable are compatible with the standard capabilities of telecommunications cables, for which a wide range of industry-approved standard, connection boxes, couplings and penetrators exist, which can be adapted to interface with scientific equipment.
Underwater connection systems technologies, available from telecommunication and oil and gas market, including deep-sea wet-mateable optical, electro-optical and hybrid electro-optic connectors, have been adapted and developed to fulfil the project requirements.
The installation and maintenance operations of such detector are difficult and expensive. In the design of the system special attention is being paid to techniques for maximizing reliability and minimizing underwater operations. All components must survive both the mechanical rigours of installation (torsion, tension due to self-weight and ship movement) and must have high reliability and long lifetime under the extreme seabed conditions (high ambient pressure of around 300 bar, aggressive and corrosive environment, lateral and torsional forces due to deep sea currents etc.).
The various technical aspects of this unusual power supply system are discussed.
