It's the same equation. A times B times C is less than X.

These hatches are approximately 3x3x1 ft. Steel weighs about 500 lbs per square ft. How would you raise and lower a 4500 lb hatch manually? They need to be heavy duty, the keep the ocean on the outside of the submarine.

Why did you think the hatches could be manually closed?

Haven't you seen Fight Club? If the cost of settling lawsuits is less than than the cost of issuing the recall then you didn't issue the recall. There is a continuum, at some point the cost of lowering the risk of a catastrophic failure becomes more than the cost of the catastrophic failure.

It is not a binary solution set. Implementing a perfect solution has associated costs. If a perfect solution that prevents this type of accident from ever happening adds $10 million in cost per overhaul and an accident of this magnitude occurs once every 500 overhauls then it is not cost effective and you're better off letting 1 out of every 500 burn.

Asbestos is fireproof. The Navy should look into using that for insulation. You should call them and let them know.

There are a lot of compartments but only three areas that can be isolated from each other: the forward compartment (everything forward of the Crew's Mess/Cold Storage in the picture you linked to), the reactor compartment and the engine room (everything aft of the reactor compartment).

Because there are hoses for temporary systems going through the hatches that take time to disconnect and the hydraulics systems required to close the hatches are all shut down.

No, they are not titanium. The US has no titanium-hulled submarines. The Miami is made of steel.