[Sneap] Information request concerning High pressure safety system in electrostatic accelerators

[Ian Vickridge]

I know of two incidents along these lines

 

1)      An AN2000 or 2500  in France, I believe under 20 bar N2/CO2, had a
catastrophic tube collapse. I didn’t see this so this is just second-hand
information. The shock wave down the open beamline shifted the analyzing
magnet and tore a turbo pump off the line. Apparently no-one was around when
this happened and there were no injuries. 

2)      A Van de Graaff in Algiers, in the 60s, was apparently filled
(either accidentally – if that is possible – or as the result of terrorist
action) with pure oxygen. When they turned it on it went ‘boom’. The tank
withstood the internal conflagration so the only damage was inside the tank.
This is second- or third-hand information which I have tried to distort as
little as possible.

 

The pressure tank people around us, have no idea at all about what might be
the dangers associated with a catastrophic tube failure under operating
pressure. I am not sure they want to know. All they want to do is put a cap
on the (empty) tank and fill it up with water to do the pressure test. We
don’t volunteer any information that is not asked for. Ours is 20bar N2/CO2
mix.

 

However, on a T at the exit of the tube we have a gravity+1bar-held 8inch
flange, with a restraining bracket to allow it to blow off without being
blasted into the ceiling or bouncing around the accelerator hall at high
speed in case of the tank emptying, for some reason or another, through the
tube. I hope it never gets tested !

 

Cheers

 

IV

 

De : sneap-bounces at tunl.duke.edu [mailto:sneap-bounces at tunl.duke.edu] De la
part de Augusto Lombardi
Envoyé : mercredi 18 mars 2009 09:41
À : sneap at tunl.duke.edu
Objet : [Sneap] Information request concerning High pressure safety system
in electrostatic accelerators

 

    Dear Sneapers,

I am Augusto Lombardi from Legnaro and some of you know me already. 
I am now responsible for the operation of the two single stage machine in
Legnaro the AN 2000 and the CN 7 MeV. 

The questions I have for the community is:

1.	    There are any risk analysis and/or records concerning the high
pressure hazard due to the column breakdown or any other accident that put
in comunication the high pressure vessel with the beam vacuum pipe? (more
than 10 bar vessels versus vacuum)
2.	    There are any safety systems for this kind of accident?  (we do
have break disks and spring loaded valves but ....)


    Thank you all for the help.
    greetings
    Augusto.

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