I think the words you're seeking are "Detonation" vs "Deflagration".
Detonation means a rather energetic release resulting in an Earth Shattering Kaboom.
Deflagration means a rather energetic release, but at a slower rate of expansion resulting in a really big plume of really hot fire.
The class of the ammunition has an impact on this - ammo is broken down into 4 main classes - 1.1, 1.2, 1.3, and, 1.4.
There are sub-classes within those (1.4S) denoting specific characteristics, however, the only munitions that I would think they'd leave onboard during a refit such as this would be small arms ammunition, and possibly some pyrotechnics such as flares and such. These fall into 1.3 and 1.4 classes.
1.1 and 1.2 is the real energetic stuff - the "High" explosives that we enjoy watching go boom.
I do not have any knowledge about what the capacity of one of these ships is, but I can imagine that it is an order of magnitude larger than what we carry on our ships, particularly since it's a ship designed to support troops going ashore, plus helicopters and aircraft dropping bombs, firing missiles and guns. If the ship was fully loaded with HE, they'd be either fighting the fire madly, trying to get to the magazines before they blew, or, evacuating blocks of space.
Consider. Here's a 'guess' at what a single magazine might contain:
500 lb bomb x 200
Sidewinder missile x 50
Hellfire missile x 500
20mm HE ammo x 50,000
The Net Explosive Quantity on these items would be:
87 Kg x 200 = 17,400 Kg
9.4 Kg x 50 = 470 Kg
8.2 Kg x 500 = 4,100 Kg
0.010 Kg x 50,000 = 500 Kg
That's a total NEQ of 22,470 Kg.
https://www.un.org/disarmament/un-saferguard/explosion-danger-area/
Plugging that in, the MINIMUM distance to clear the public from is 2,359 meters...so they'd be clearing a pretty large space of the town for this one magazine example....and a fully loaded warship designed to support ground and air elements would have a lot more than that.
If the ship was loaded up with ammo, they'd be clearing the area for literally miles in case it blew up.
The good news is that some of the ammo would 'only' burn - rather than detonate. It would depend considerably upon the type of ammo though, and what it's being exposed to. Once something goes 'high order', the shockwave would likely cause sympathetic detonations amongst ordnance that was destabilized.
Or something like that.
From my perspective, having been a magazine custodian for a ship - they are not treating this like they would a ship that had magazines full of HE.
NS