Reindeer farms and grazing Holstein cows dot a vast stretch of rolling green pasture here on Japan's northern tip. Underground it's a different story. Workers and scientists have carved a sprawling laboratory deep below this sleep dairy town that, despite government reassurances, some of Horonobe's 2,500 residents fear could turn their neighborhood into a nuclear waste storage site. Japanese utilities have more than 17,000 tons of spent" fuel rods that have finished their useful life but will remain dangerously radioactive for thousands of years. What to do with them is a vexing problem that nuclear-powered nations around the world face, and that has come to the fore as Japan debates whether to keep using nuclear energy after the 2011 disaster at Tokyo Electric Power Co.'s Fukushima plant. The answer to that problem may lie in the Horonobe Underground Research Center, which has been collecting geological data to determine if and how radioactive waste can be stored safely for as long as 100,000 years in a country that is susceptible to volcanic activity, earthquakes and shifting underground water flows. But as with America's doomed Yucca Mountain project, finding a community willing to host a radioactive dump site is proving difficult, even with a raft of financial enticements. One mayor expressed interest in 2007, and was booted from office in the next election.