For the first time in U.S. history, a civilian nuclear plant will be making radioactive tritium for use by the government in manufacturing nuclear weapons. The Tennessee Valley Authority`s (TVA) Watts Bar Nuclear Plant near Spring City, Tenn., could begin making tritium as early as 2003, while continuing to generate electricity. TVA`s Sequoyah plant near Chattanooga, Tenn., will serve as a backup. Under the contract, TVA will be reimbursed an estimated $25 million for its preparation efforts in the first three years. If tritium gas production begins, TVA will get about $10 million for each year of production. If no tritium were produced over a 10-year period, TVA would still receive a total of $50 million, including the $25 million for preparing for production.