Whose guns were doing the shelling? And even more to the point, was there sufficient damage to compromise even one containment barrier?

The VVER1000 pressurized water reactor utilizes 163 fuel assemblies and there are 6 reactors. If 1/3 are replaced during a refueling cycle of 18 months (not certain on that, they may be replaced yearly) and then these spent fuel assemblies held for five years in pools prior to being dry casked, then about 50 would be replaced during each reactor's refueling. An 18 month cycle means that each reactor would generate about 150+ spent assemblies in five years or 900+ total. Each reactor likely has its own spent fuel pool due to the transfer process from reactor to pool being done under water. These pools are probably not in the containment area. The pools are where the problem lies, not the reactors. The pools are more vulnerable and become very dangerous if the assemblies are exposed.