11:21 Mar 26, 2011 

not all of us have the same interest upturned skirts.

If it is as you say, it could be a "secondary containment" like the plastics "pallets" they stand drums of chemicals in, lest they should leak.
Still guesswork though ...

08:13 Mar 26, 2011 

...and have tried to reconcile it thus:
If we assume that a 'jupette' is a kind of 'skirt', perhaps it means a sort of surround that turns up at the edges — so it would catch anything spilling over; so this would amount to the same thing as if the autoclave were to be stood in a tray.

Could that make sense?

Still haven't got a clue what to call it, though!

03:54 Mar 26, 2011 

autoclaves might have drip pans, but jupette (vertical) strikes me as an odd word for what amounts to a lèche-frites (horizontal), even if we leave the mussels out of it.