This is arguably the most difficult section of the entire vehicle. It contains extensive shielding to protect both against normal flight conditions and a worst case engine fire or RUD (rapid unscheduled disassembly). In the event of an engine shutdown, well protected propellant pre-valves and pressurant fuse valves immediately cut off flow to that engine.Space Exploration Technologies Corporation - Updates
I wanted to post this mainly because I'd never encountered the acronym "RUD" before and it made me grin. But I'd encourage anybody with any interest in spaceflight to read the whole update. I got it in email, but that link will take you to the same text. It has lots of pictures of work on Falcon 9, as well as some test firing footage of the Merlin engine. Excellent stuff!
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