prvi hrvatski speleološki kongres - KARST underground protection

concrete box near the cave’s entrance. Inside this box you can also find the utility
main switch equipped with an emergency release coil, to which the main riser, which
consists of FG7 cables, is connected, and takes up to the main utility switchboard,
which is located in a special technical room in the basement of the Visitors reception
centre of the Grotta Gigante. This switchboard is equipped with special protections for
the entire electrical system, which is divided in two main areas, one for the circuits
relating to the Visitors reception centre and the other one for the circuits relating to
the cave. The electrical system is entirely protected by an uninterruptible power
supply, always on-line, located next to the main switchboard, in the same room. It is
also protected by a diesel generating set, in a separated room, for emergency use in
the event of unavoidable malfunctioning or black-outs of the system. The earthing
system consists of a 50 mm 2 -section bare copper wire connected to the reinforcing
bars of the foundation plinths of the Visitors reception centre building. This wire is
connected to the main earthing terminal within the main utility switchboard, from
which the various protective conductors, with the same section as phase conductors,
are distributed to the circuits.
Radon Concentration trend in a tourist cave (NE Italy)
Koncentracija radona u turističkoj spilji Grotta Gigante (SI Italija)
M. Garavaglia 3 , C. Giovani 3 , L. Piccini 3 , F. Cucchi 4 , L. Zini 4 & Alessio
Fabbricatore 1,2
1
Direttore Grotta Gigante, Trieste, Italy
2
Società Alpina delle Giulie , Trieste del Club Alpino Italiano
3 Friuli Venezia Giulia Regional Agency for Environmental Protection, Italy
4 Geosciences Department, Trieste University, Italy
Key words: Karst, Giant cave, Trieste, caves,
Ključne riječi: krš, Grotta Gigante, Trst, spilje,
Elevated concentration of Rn-222 have been recorded in many limestone
caves throughout the world. In some cases it represents an impact and risk for who
works in the caves and it is necessary to estimated dose to workers.
In any case it is of interest to study spatial distribution and time variation of
radon concentration inside the caves. This paper concerns a study lasted over than one
year in a very large tourist cave near Trieste (NE Italy). After a first study that
excluded risk for workers and visitors, a more detailed study was performed to
analyze the distribution of radon concentrations in the different part of the cave and to
observe the trend during the year. Different kind of measurements were performed:
short measurement by E-Perm electrects to study radon concentrations distribution in
the cave and long term measurements by active instruments RAD-7 to study radon
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