Yes and no. MRI's require large amounts of cryogens (LN2, LHe) which would likely be impossible to get during the siege. The magnets likely quenched well before.

All of these items are accounted for when feasibility studies are conducted for new plants (and even old plants up for license renewal). Chernobyl was due to the type of reactor (which doesn't exist in the US), 3 Mile Island resulted in no adverse effects to health or environment and led to more stringent training and equipment upgrades, and Fukushima was built in a poorly selected location.

Of course there's risk involved with nuclear, but we mitigate those risks appropriately. We don't stop driving cars because of deadly accidents - we engineer safety systems to mitigate risk.