Level 5, Yellow Key

I am stuck on what I think is level 5 (the one with loads of radioactive stuff in sewers). I need the yellow key, yet it is unobtainable, surrounded by a moat of Radioactive stuff.

PS/OT: Things I noticed about this forum and find funny:
1: The "New Topic" button is at the bottom of the first page, forcing you to at least skim the first page.
2: The default "Topic Type" is DUMB.

You can walk up there. Running will be easier.