A nuclear battleship shell at Guadalcanal

What happens if Washington's first 16-inch shell at Guadalcanal becomes a Cold War nuclear shell on the same trajectory?

The target is annihilated and nearby fleets suffer destructive blast, flash, water, and electromagnetic effects.

Replacing Washington's opening shell with a nuclear round turns the night action into a fleet-wide catastrophe. The target and nearby ships would face blast, heat, and a large water disturbance rather than a conventional armor-penetration problem. South Dakota's already fragile electrical situation would be exposed to electromagnetic effects. Personnel on open decks or using optical instruments could suffer severe injury even aboard ships outside the immediate destruction radius.