Patent Number: 
Section: claims

1. A communication network for a nuclear power plant protection system, which comprises: a plurality of monitoring and control channels, comprising a first pair of channels which includes a first and second channel, said first pair of channels directly communicating with a second pair of channels which includes a third channel and a fourth channel, through a network of data paths;  a plurality of engineered safety feature trains, comprising a first train and a second train, said first train communicating directly with said first pair of channels, and communicating directly with said second train, said communicating occurring through said network of data paths, said second train communicating directly with said second pair of channels, and communicating directly with said first train, said communicating occurring through said network of data paths;  a first vital power bus, individually powering said first channel;  a second vital power bus, individually powering said second channel, and redundantly powering said first train together with said first vital power bus;  a third vital power bus, individually powering said third channel; and  a fourth vital power bus, individually powering said fourth channel, and redundantly powering said second train together with said third vital power bus. 2. A communications network as set forth in  claim 1 , which further comprises: claim 1 a first plurality of modems associated with each of said monitoring and control channels; and  a second plurality of modems associated with each of said engineered safety feature trains. 3. A communications network as set forth in  claim 2 , wherein said first vital power bus individually powers a first group of modems, said second vital power bus individually powers a second group of modems, said third power bus individually powers a third group of modems, and said fourth vital power bus individually powers a fourth group of modems, said first, second, third and fourth groups of modems being part of said first plurality of modems. claim 2 4. A communications network as set forth in  claim 2 , wherein said first vital power bus redundantly powers a fifth group of modems, together with said second vital power bus, said fifth group of modems being part of said second plurality of modems, and claim 2 said third vital power bus redundantly powers a sixth group of modems, together with said fourth vital power bus, said sixth group of modems being part of said second plurality of modems. 5. A communications network as set forth in  claim 1 , wherein said data paths are optical fiber paths, connected by fiber optic modems. claim 1