The arrival by small boat of the Mumbai terrorists reminds me of a persistent fear here. A small freighter or a large one loaded with containers will pull into Conley Terminal in South Boston and shortly thereafter a dirty bomb will go off. This will spread a small cloud of nuclear materials, dust size particles into the air. The weather that day is blustery and on shore. Soon, radioactive particles will be spread over South Boston and into the South End. Tens of thousands will ingest particles. Panic will test those signs saying “Evacuation Route”.