The following potential hazards have been identified:
The system is supplied by 220Vac and 110Vac. There is a magneto-thermic and
differential switch at the very first entrance of the power supply.
All the lines at these voltages are kept inside the racks, and the plugs
satisfy the European CE rules for these voltages.
The supply for the single devices inside the racks is all
at 5VCC, 12VCC, 24VCC, except for the pump which needs 110VCC and
for the Motor Drivers, which need a special 80VCC voltage. A custom
power supply unit has been built for this purpose, and this unit is kept in the
so-called "Power Supply Unit" at the bottom of the left rack, together with the
other supply units. The signal lines are low voltage (
12VCC the digital
lines, 0-5V or 4-20mA loops the analog ones) and kept separated from the
supply lines by using different connectors and separated cables.
Optocouplers have been used for the microswitch line-in, isolated input
lines have been used for the analog lines. A potential hazard outside of
the racks, is the motor cables, which must be touched only
by AUTHORIZED PERSONNEL and with the power supply switched
off. An 80VCC/2A (square wave, duty cycle 0,5) current flows in
these cables when motors are in stand-by mode. This current goes up
to 7A (square wave, duty cycle 0,5) when motors are moving;
these high power lines are everywhere kept separated from the
low voltage lines. The pump power supply line is
kept inside the racks, and in a position that cannot be reached
unless opening the side panel of the right rack.
This system is a potential hazard only if hydrogen is used. The
volume is 
10 liters. The pressure is 1.02 atm.
The target cell for gas tightening has been tested up to 2 bars.
The gas transport tubes are made of stainless steel, 6 mm in
diameter. The electro-valves are anti-deflagrant according to the USA
regulations, working at low voltage (24V AC). All the power supplies for
this section are kept separate in a different rack.
The default value for the valves, which is at the released position if power supply fails, is "closed". Regulating the pressure on the gas cylinder to 0.2 atm avoids the pressure in the target cell overriding this value even in the case of valve failure. Both the manual valve and the remote valve control require the operator to keep pressing the button either on the front panel of the right rack, or by using the mouse button on the corresponding icon from the computer, in order to keep the valve open. If the button is released, the valve will go back to the default value, i.e., closed.
Any leakage from the cell would be immediately detected by the
scattering chamber vacuum measuring system.
Leakages outside of the scattering chamber would spill in the surrounding
atmosphere in the Hall. However, because of the small amount due to
small gas overpressure, this should not represent
a potential hazard for the people working in the hall.
In any case, there are two pressure transducers in front of the right rack;
their values can be seen both in the Hall A directly on the panel,
and in the Counting House on the computer, or on the display through the
camera, which should reveal immediately if there is any leakage.
There are about 17 liters of pure water in the circuit.
The water tank, the tubes,
the target and the cell containing it, are made
of stainless steel. The tubes are joined by "swagelok" connectors.
The entrance and exit windows for beam passing through are made of 75 
m
Be; the two side windows are made of 1 mil stainless steel.
The cell has been tested up to 2 bars for gas leaks. No water leakage is expected unless the windows of the target cell break. In this case some water, carrying some radioactivity, goes into the scattering chamber.
The calculations performed by Geoff Stapleton show that the radiological precautions necessary are rather low. The water should not leak into the hall drains. Measurements at convenient intervals will be made by the radiation control group on samples, to permit determinations of the radionuclides yields. In case of water loss or draining water, the radiation control group has to be informed to take precautionary measurements.
There are no significant hazards in working with this system,
due to the low voltages and very small currents.
However, one must switch the power off to
the whole system before opening and working on the system.
ONLY AUTHORIZED PERSONNEL are allowed to touch the signal lines.
There are no particular risks in touching the mechanisms,
except when the system
is in motion. In this case one has to beware of the cog-wheel's movements,
by keeping his hands away; for this reason, it is FORBIDDEN to touch the
moving system when motors are moving.