Corrected entry: In the opening scene it is discussed whether the soviet nuclear torpedoes will explode when hit by the cruise missile. One of the officers says it might. But nuclear bombs can't go off unless the actual trigger mechanism is activated. They do not contain powder or dynamite or anything which can explode when heated.
Grumpy Scot
4th Feb 2013
Correction: Incorrect. Nukes have a core of fissionable materiel surrounded by high explosives. While there is no chance that there would be a nuclear detonation, the cruise missile could cause the explosives to detonate contaminating the area with highly radioactive debris and flinging more of it into the atmosphere to be spread.
Grumpy Scot