The Nuclear Regulatory Commission has essentially accepted the industry's rationale on the safety of dense-packing fuel rods. Over the last two decades, the agency has repeatedly approved license applications by utilities to pack more rods into the pools.
Nuclear safety experts say that plants have packed up to five times more spent fuel rods than the pools were designed to store, though Nuclear Energy Institute officials say the pools contain no more than twice their original capacity.
The only advantage to keeping the pools packed so tightly is the cost of the dry casks, which would run about $5 billion to $10 billion nationwide, said Frank N. von Hippel, a Princeton University physicist who first disclosed the problem in a paper he co-wrote in 2003. He said he considers fixing the fuel pool problem one of the most important steps toward making U.S. nuclear plants safer.
"It is such a huge risk that it is worth the cost," he said. "We may not be as lucky as the Japanese were to have the wind blowing the radioactive emissions out to sea."